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We describe the performance of a colorimetric reagent kit (Diagnostic Systems Laboratories, Inc., Webster, TX 77598) for measuring calcium directly in urine, serum, and ultrafiltered serum, and compare the results with those obtained with atomic absorption spectrophotometry. The CV for within-run precision was 2.8 and 2.1% for urine and whole serum, respectively (n = 10 each). Between-run precision for urine, whole serum, and ultrafiltered serum was 1.9, 1.6, and 2.2%, respectively (n = 8 to 10). Analytical recovery of added calcium from three different urine and serum specimens, to which three different concentrations of calcium had been added, was 101.9 (SD 0.3%) for urine and 100.9 (SD 0.2%) for serum. Assay of 30 urine specimens, 15 ultrafiltered serums, and 20 whole serums by both the kit and atomic absorption spectrophotometry demonstrated correlation coefficients of 0.993, 0.828, and 0.751, respectively. Mg2+, hemolysis, or lipemia does not interfere. Compared with atomic absorption spectrophotometry, the calcium kit procedure is rapid and simple. | A procedure has been worked out for the micro estimation of calcium in various types of biological samples with o -cresolphthalein complexone as an indicator. This reagent is more sensitive than the other commonly used indicators such as eriochrome black T and murexide. Test solutions containing 2–5 μg calcium can be conveniently dealt with and the method may have a special application in the analysis of radio-contaminated samples. Though strontium and barium also react selectively with this reagent, their effect is negligible because these two elements normally occur in traces. On the other hand, the most significant effect is due to the presence of magnesium. This interference has been overcome by the use of 8-quinolinol and the method is thereby rendered simple and direct. Results obtained are comparable to those found by the usual standard procedure. In contrast to the method applicable directly to biological fluids such as serum, urine, sweat, milk, and water, an additional step involving prior ashing is required in the case of plant materials. The application of this method may thus be extended further. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,200 |
This disclosure generally relates to novel formulations containing the active ingredient thyroid stimulating hormone (TSH) having modified pharmacokinetic profiles as compared to prior art formulations. | Intramuscular chloroquine is rapidly absorbed, even in severe falciparum malaria, and may cause potentially lethal hypotension. Less rapidly absorbed formulations should be safer. A chloroquine phosphate solution containing 2% methylcellulose 1500 released chloroquine 2.6 times more slowly than a commercial aqueous solution in an in-vitro absorption simulator. There was a log linear relationship between viscosity and release rate. The absorption pharmacokinetics of the more viscous chloroquine phosphate solution were then compared with those of a commercial solution after intramuscular injection to eight rabbits in an open cross over comparison. The rate of absorption was over three times slower with the viscous solution; median time to peak whole blood concentration with the commercial aqueous solution was 10 (range 5-20) min compared with 30 (range 10-60) min for the more viscous formulation (P less than 0.05). Peak whole blood concentrations were 66% (95% CI 50-82%) of those with the commercial preparation, but the acute bioavailability of the two solutions was similar. This simple new formulation may be safer than currently available chloroquine preparations and should now be evaluated in man. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,201 |
The combination of field asymmetric waveform ion mobility spectrometry with liquid chromatography-mass spectrometry (LC-FAIMS-MS) has been developed for the analysis of glucuronide and sulfate metabolites of seven anabolic-androgenic steroids in urine. Separation by FAIMS-MS was investigated in positive ion mode for selected cationic adducts (H+, NH4+, Na+, K+, and Cs+). LC-FAIMS-MS analysis of the doubly sodiated adducts ([M + 2Na - H]+) of isobaric and coeluting steroid metabolites allowed their rapid (8 min) qualitative and quantitative determination in spiked urine using hydrophilic interaction liquid chromatography prior to FAIMS-MS separation, with discrimination >95% achieved between the steroids investigated. A quantitative evaluation of the LC-FAIMS-MS method was performed giving limits of detection in the range 1-6 ng mL-1, limits of quantification in the range 3-20 ng mL-1, with reproducibility (%RSD < 10%; n = 6) and linearity (R2 > 0.99). The LC-FAIMS-MS method demonstrates increases in signal-to-noise ratios for the doubly sodiated steroid metabolites in unspiked urine (>250%) by the reduction of isobaric interferences from the matrix. An alternative or additional tool for identification of the steroid metabolites is based on the observations of different patterns of sodium acetate clusters that are characteristic for each metabolite. | Differential ion mobility spectrometry (DMS) spatially separates ions in the gas phase using the mobility differences of the ions under applied low and high electric fields. The use of DMS as an ion filter (or ion selector) prior to mass spectrometry analysis has been compromised by the limited ion transmission efficiency. This paper reports enhancement of the DMS-MS sensitivity and signal stability using a modified CaptiveSpray™ source. In terms of the ion sampling and transmission efficiency, the modified CaptiveSpray source swept ~ 89% of the ions generated by the tapered capillary through the DMS device (compared to ~ 10% with a conventional microspray source). The signal fluctuation improved from 11.7% (relative standard deviation, RSD) with microspray DMS-MS to 3.6% using CaptiveSpray-DMS-MS. Coupling of LC to DMS-MS via the modified CaptiveSpray source was simple and robust. Using DMS as a noise-filtering device, LC-DMS-MS performed better than conventional LC-MS for analyzing a BSA digest standard. Although LC-DMS-MS had a lower sequence coverage (55%), a higher Mascot score (283) was obtained compared to those of LC-MS (sequence coverage 65%; Mascot score 192) under the same elution conditions. The improvement in the confidence of the search result was attributed to the preferential elimination of noise ions. Graphical ᅟ. | By using a superluminescent diode as the light source and a depolariser inside the fibre coil, a constant scale factor is achieved without using polarisation control elements. For long-term behaviour an RMS-bias drift of 10 degrees/h is obtained. | eng_Latn | 27,202 |
The major objective of this investigation has been to determine the mechanism by which 3-BHA induces forestomach tumours in rodents. In vitro studies of liver microsomal metabolism of [ 14 C]-3-BHA show binding of metabolites to microsomal protein which could be markedly decreased by addition of l -cysteine. p -Toluenesulphonic acid hydrolysis of the labelled microsomes showed a radioactive peak that co-chromatographed with the major product of the reaction of tert -butylquinone ( tert -BuQ) and l -cysteine. In vivo binding of metabolites of [ 14 C]-3-BHA to microsomal protein of the forestomach, glandular stomach and liver was determined. Forestomach microsomal protein contained 14 times as much bound radioactivity as glandular stomach and 12 times as much as liver. HPLC studies showed marked qualitative differences in the distribution of labelled compounds in hydrolysates of microsomes from the three tissues. The forestomach contained peaks not present in the other two tissues. In other studies it was shown that the 3- tert -butyl-5-methoxy-1,2-benzoquinone reacted rapidly with NADPH and NADH. tert -BuQ did so more slowly. Current data suggest that two factors may be of importance for 3-BHA carcinogenesis. The first is thiol depletion resulting from direct binding of quinone metabolites of 3-BHA to tissue thiols. Secondary reactions due to the presence of the quinones could also deplete — SH groups. Such thiol depletion could account for the threshold level existing for 3-BHA carcinogenesis. The second factor is an attack on tissue constituents from reactive metabolites of 3-BHA, as is evident from protein binding, and possibly also from oxygen radicals produced as a result of redox cycling of quinone and hydroquinone metabolites of 3-BHA. | Modifying effects of the environmental contaminant catechol, and its isomers resorcinol and hydroquinone, on methyl- N -amylnitrosamine (MNAN)-induced carcinogenesis were studied in male F344 rats. Groups of 15 rats were given three i.p. injections of 25 mg/kg of body weight of MNAN within the initial 2-wk period, and commencing 1 wk thereafter they were administered 0.8% catechol, 0.8% resorcinol, or 0.8% hydroquinone in powdered basal diet or were given basal diet alone for 49 wk. Additional groups of 10 to 15 rats were similarly treated without prior carcinogen exposure. Histological examination after sacrifice at wk 52 revealed that the incidences of tongue papillomas and esophageal squamous cell carcinomas in the groups given MNAN followed by catechol (57.1% and 64.3%) or resorcinol (50% and 58.8%) were significantly higher than those in the carcinogen only controls (9.1, and 0%, respectively). Hydroquinone also enhanced the development of esophageal squamous cell carcinomas but was less active than catechol or resorcinol. The incidence of alveolar hyperplasia in the lungs of the group given MNAN followed by catechol (0%) was, in contrast, significantly reduced as compared to the control value (54.5%). Hydroquinone and resorcinol showed a similar but nonsignificant tendency. These results indicated that the environmental contaminant, catechol and its isomers, may play a role in the development of human upper gastrointestinal cancer, in addition to exerting modifying effects in other organs. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,203 |
High-quality vinegars are traditionally produced by aging them in barrels or bottles. However, these processes are very time-consuming. To accelerate of Zhenjiang vinegar maturation, the ultrasound was used to treat the steeped vinegar. Results showed that, the optimum ultrasonic power, time and ethanol addition for aging vinegar were determined to be 50W/100mL, 75min and 0.75% (V/V), respectively. Under the optimum experimental conditions, the total amino acid of fresh vinegar decreased from 1082.259mg/100mL to 871.045mg/100mL. Several volatile components increased significantly, such as the total esters, aldehydes and heterocyclic. Total non-volatile organic acids increased from 202.59mg/10mL to 233.87mg/10mL. The changes of above-mentioned components develop towards the direction of mature vinegar. Coupling the HS-SPME/GC-MS analysis data with Principal Components Analysis, ultrasonic treatment vinegar was determined to be equivalent to 2-3years of natural aged Zhenjiang vinegar. This study has showed that ultrasound is promising not only in shortening the aging time and lowering costs for the vinegar-making industry, but also in producing fine vinegar. | Zhenjiang aromatic vinegar (ZAV) is one of the well-known fermented condiments in China, which is produced by solid-state fermentation. It can be classified into traditional Zhenjiang aromatic vinegar (TZAV) and industrial Zhenjiang aromatic vinegar (IZAV) because of different production methods. The purpose of the study was to evaluate the variations and differences on chemical compositions and antioxidant activities of TZAV and IZAV during the aging process. The proximate composition, organic acids content, total phenolic content (TPC), total flavonoid content (TFC), total antioxidant activity (TAA) and phenolic compounds composition of TZAV and IZAV were detected during the aging process. Organic acids contents, TPC, TFC, TAA and phenolic compounds contents in ZAV were increased during the aging process. Acetic acid, lactic acid and pyroglutamic acid in ZAV were major organic acids. With the extension of aging time, TZAV and IZAV had similar proximate compositions and organic acids content. The values of TPC, TFC and TAA were higher in TZAV than in IZAV when aging is more than 3 years. Rutin and p-coumaric acid were detected in TZAV but not in IZAV. In principal component analysis (PCA), TZAV and IZAV can be divided into two groups according to their phenolic compounds composition. These findings provide references for evaluating TZAV and IZAV on the basis of their characterizations. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,204 |
M. S. Tswett contemplated the possibility of “chromatography” in 1899–1901 while carrying out his first research work on the physico-chemical structure of plant chlorophylls, and he reported “on a new category of adsorption analysis” in 1903. The evolution of chromatography followed the advances of this century: each decade brought new innovations based logically from the previous one. By the end of the 20th Century chromatography has became the most widely used separation technique in chemistry and biochemistry: thus, it is no exaggeration to call it the separation technique of the 20th Century. This paper investigates the evolution of the various branches of chromatography. | The chiral separation of enantiomers is crucial for pharmacovigilance within drug discovery. Although a large number of prescribed medications are marketed as pure enantiomers, this is not always the case and many are in fact racemic mixtures. Drug scandals, such as that of Thalidomide in 1961, provide a clear example of the social and economic repercussions that can be caused by negligence of these chiral compounds. Two high performance liquid chromatography (HPLC) methods are presented to determine, separate and quantitate a commonly prescribed chiral beta blocker, (-)-Alprenolol. The first method utilises a chiral column to physically separate the two enantiomers of Alprenolol in 25 minutes, before quantitating with two detectors. Fluorimetry gave the better limit of detection of 0.16-0.41ng and a correlation coefficient of 0.999. The second method used an achiral column coupled with polarimetry to quantitate (-)-Alprenolol without the need for physical separation in 10 minutes. The limit of detection achieved was 27-37μg and demonstrated a correlation coefficient of -0.999. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,205 |
Ingested arsenic is known to be not only excreted by urine, but to be stored in sulphydryl-rich tissue like hair, nail or skin. We developed an extraction method for arsenic species from these tissues and studied the stability of different arsenic species during the extraction process. Inorganic and pentavalent methylated arsenic was found to be stable under the extraction conditions, whereas trivalent methylated arsenicals and the thio-analogue of DMAV (DMAS) showed reduced stability. The absorption ability of hair for these different species was studied as well. Inorganic arsenic is better absorbed by hair than monomethyl- or dimethyl-arsenicals, whereby the trivalent forms are taken up better than the pentavalent forms. Independent of which methylated arsenical was used for the incubation, the pentavalent form was always the dominant form after extraction. Hair and nail samples from humans suffering from chronic arsenic intoxication contained dominantly inorganic arsenic with small and strongly varying amounts of DMAV and MAV present. DMAS was only found in some nail sample extracts containing unusually high amounts of DMAV and is believed to be formed during the extraction process. | This study showed the relevance of using chromosomal aberration (CA) as potential indicators of sodium arsenite (SA; NaAsO2) cytotoxicity. The study investigated cytotoxic potential of SA in Oreochromis niloticus using CA assessment. The fish were exposed to four different concentrations of SA (5, 10, 20 and 40 mg/L) for 24 hours in comparison to a control group. The As concentrations in the samples were analysed by inductively coupled plasma atomic emission spectrometry. The differences in As concentrations in the water and O. niloticus samples between the control and experimental groups were significant (p<0.05), whereas the within experimental group differences were not significant. The cytotoxic assessment of SA in O. niloticus revealed five types of CAs, including single chromatid gaps (SCG), single chromatid break (SCB), centric gap (CG), fragmentation (F) and deletion (D). The most common CA in the O. niloticus samples was SCG. A total of 2.33, 10.67, 18.67, 18.00 and 23.67% of the cells in the control and experimental groups exhibited CAs. The numbers of CAs and cells with CAs from the control and experimental groups of fish were significantly different (p<0.05); additionally, the fish exposed to 5 and 40 mg/L showed significant within experimental group differences (p<0.05). | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,206 |
A large variety of log P calculation methods failed to produce sufficient accuracy in log P prediction for two in-house datasets of more than 96000 compounds contrary to their significantly better performances on public datasets. The minimum Root Mean Squared Error (RMSE) of 1.02 and 0.65 were calculated for the Pfizer and Nycomed datasets, respectively, in the ‘out-of-box’ implementation. Importantly, the use of local corrections (LC) implemented in the ALOGPS program based on experimental in-house log P data significantly reduced the RMSE to 0.59 and 0.48 for the Pfizer and Nycomed datasets, respectively, instantly without retraining the model. Moreover, more than 60% of molecules predicted with the highest confidence in each set had a mean absolute error (MAE) less than 0.33 log units that is only ca. 10% higher than the estimated variation in experimental log P measurements for the Pfizer dataset. Therefore, following this retrospective analysis, we suggest that the use of the predicted log P values with high confidence may eliminate the need of experimentally testing every other compound. This strategy could reduce the cost of measurements for pharmaceutical companies by a factor of 2, increase the confidence in prediction at the analog design stage of drug discovery programs, and could be extended to other ADMET properties. | Common drugs intended for action in plasma (antibacterials, antiallergics, diuretics...) often display both acidic and basic behavior, and some of these amphoteric compounds can appear as zwitterions. In such cases, accurate profiling of lipophilicity vs. pH, which plays a fundamental role in drug pharmacokinetics, might be complex. In the present work two common lipophilicity determination methods based on the drug distribution between 1-octanol and aqueous buffer i.e. phase equilibration (shake-flask) and two-phase titration (potentiometry), were compared with a high-throughput lipophilicity index, the Chromatographic Hydrophobicity Index (CHI). The results were also compared with log Do/w pH-profiles calculated by different algorithms from ACD/Labs. Accurate and similar results were obtained for both octanol-water approaches but, due to the lower determination times and the absence of different ion-pairing buffers, potentiometry was shown to be the most convenient method. CHI vs. pH profiles provide rapid and efficient information, which is very convenient for lipophilicity screening purposes, but may differ slightly from shake-flask and potentiometric results. | The problem of the strong regularity for square matrices over a general max–min algebra is considered. An O( n 2 log n ) algorithm for recognition of the strong regularity of a given n × n matrix is proposed. The algorithm works without any restrictions on the underlying max–min algebra, concerning the density, or the boundedness. | eng_Latn | 27,207 |
The purpose of this paper was to better understand the role of polyamine transport in pancreatic cancers.This paper identifies potential biomarkers for assessing the relative tumor commitment to polyamine biosynthesis or transport. Cell lines with low polyamine import activity and low ATP13A3 protein levels appear committed to polyamine biosynthesis and required high concentrations of the polyamine biosynthesis inhibitor, difluoromethylornithine (DFMO) to inhibit their growth (e.g., AsPC-1 and Capan 1). In contrast, cell lines with high polyamine import activity and high ATP13A3 protein expression (e.g., L3.6pl) demonstrated a commitment to polyamine transport and required lower DFMO concentrations to inhibit their growth. Pancreatic cancer cell lines which were most sensitive to DFMO also gave the highest EC50 values for the polyamine transport inhibitors (PTIs) tested indicating that more PTI was needed to inhibit the active polyamine transport systems of these cell lines. Most significant is that the combination therapy of DFMO+PTI was efficacious against both cell types with the PTI showing low efficacy in cell lines with low polyamine transport activity and high efficacy in cell lines with high polyamine transport activity. High ATP13A3 protein expression and moderate to low Cav-1 protein expression was shown to be predictive of tumors which effectively escape DFMO via polyamine import. In summary, this report demonstrates for the first time the role of ATP13A3 in polyamine transport and its use as a potential biomarker along with Cav-1 to select tumors most susceptible to DFMO. These findings may help stratify patients in the ongoing clinical trials with DFMO-based therapies and help predict tumor response. | All mammalian cells depend on polyamines for normal growth and proliferation, but the exact roles of polyamines at the molecular level remain largely unknown. The RNA-binding protein HuR modulates the stability and translation of many target mRNAs. Here, we show that in rat intestinal epithelial cells (IECs), polyamines enhanced HuR association with the 3'-untranslated region of the c-Myc mRNA by increasing HuR phosphorylation by Chk2, in turn promoting c-Myc translation. Depletion of cellular polyamines inhibited Chk2 and reduced the affinity of HuR for c-Myc mRNA; these effects were completely reversed by addition of the polyamine putrescine or by Chk2 overexpression. In cells with high content of cellular polyamines, HuR silencing or Chk2 silencing reduced c-Myc translation and c-Myc expression levels. Our findings demonstrate that polyamines regulate c-Myc translation in IECs through HuR phosphorylation by Chk2 and provide new insight into the molecular functions of cellular polyamines. | Accounting for aroma production in different aromatic indica rice varieties based on variations in the levels of concerned metabolites and enzymes is poorly explored. The present investigation was, therefore, focused on unraveling the differential levels of metabolites and activities of enzymes related to aroma formation in eleven indigenous aromatic rice varieties, as compared with four non-aromatic varieties. The levels of metabolites such as proline (Pro) and Δ1-pyrroline-5-carboxylate (P5C), and the activity of related enzymes such as proline dehydrogenase (PDH), Δ1-pyrroline-5-carboxylate synthetase (P5CS), and ornithine aminotransferase (OAT) were comparatively higher in the aromatic varieties, with Kalonunia and Tulaipanji registering the highest Pro, Kalonunia the highest P5C content, Gobindobhog with the highest PDH activity, Gobindobhog and Tulaipanji with the highest P5CS, and Pusa Basmati-1 with the highest OAT activity. The levels of putrescine (Put) and γ-aminobutyric acid (GABA) were comparatively lower in aromatic varieties, with concomitant higher diamine oxidase (DAO) activity, especially in the varieties Gobindobhog and Tulaipanji. The betaine-aldehyde dehydrogenase 2 (BADH2) enzyme activity was remarkably lesser in aromatic varieties, especially Radhunipagal and Gobindobhog. Though the metabolites such as glycine–betaine and higher polyamines such as spermidine and spermine showed no specific trend with respect to their quantitative level in either aromatic or non-aromatic varieties, they were notably lower in the aromatic varieties such as Gobindobhog, Kalonunia, and Tulaipanji, indicating a possibility of their involvement in aroma formation. Therefore, the levels of metabolites such as Pro, P5C and methylglyoxal (MG), and the activity of enzymes such as PDH, P5CS, OAT, and DAO were comparatively higher in the aromatic rice varieties than the non-aromatic ones, whereas the levels of Put, GABA, and BADH2 were lower. Overall, the present study showed that there exist variations in the accumulations of such metabolites as well as differential activity of enzymes controlling their production, which altogether regulate generation of aroma in aromatic varieties. | eng_Latn | 27,208 |
The trimethylsilylation of ethambutol base and ethambutol hydrochloride was studied by means of GC/MS. The derivatisation is shown to proceed in two distinct steps, and the second derivative is identified, by both chemical ionisation and electron impact Ms, and the di-trimethylsilyl ethambutol. Most of the major mass fragments observed are assigned. A tablets assay method, based on the direct trimethylsilylation of ethambutol hydrochloride in tablets, is also described. It is simple, rapid, and unaffected by the presence of the common excipients in the tablets. | A technique is presented for the specific and sensitive determination of ethambutol concentrations in plasma, bronchoalveolar lavage (BAL), and alveolar cells (AC) using a high-pressure liquid chromatographic (HPLC)‐tandem mass spectrometric (MS‐MS) method. The preparation of samples requires a deproteinization step with acetonitrile. The retention times for ethambutol, neostigmine bromide, and propranolol are 2.0, 1.4, and 1.1 min, respectively, with a total run time of 2.8 min. The detection limits for ethambutol are 0.05 µg/mL for plasma and 0.005 µg/mL for the BAL supernatants and AC suspensions. The assay has excellent performance characteristics and has been used to support a study of the intrapulmonary pharmacokinetics of ethambutol in human subjects. | The dehydrogenation of light alkanes, especially propane and butane, is widely exploited for the large-scale production of corresponding olefins. The industrial application of the direct dehydrogenation of light alkanes is limited due to reaction and thermodynamic constraints. The dehydrogenation of light hydrocarbons involves the breaking of two carbon–hydrogen bonds with the simultaneous formation of a hydrogen and carbon-carbon double bond selectively. It may appear to be simple, but their endothermic nature and selectivity control at higher temperature is difficult. The same technologies with minor changes in process and catalyst were used for the production of both propane and isobutane dehydrogenation. The economic analysis of the available technologies based on the specific consumption of feedstock, operational ease, and capital investment indicates an internal rate of return ~25%. The attractiveness of light alkane dehydrogenation is largely dependent on the difference in feedstock and the price of olefins produced. The available technologies and how they manage reaction constraints at commercial scale have been compared. The possible solution for improvement is by focusing on catalyst improvements and the unique design of reactors. | eng_Latn | 27,209 |
For the analysis of the 16 PAH (EFSA-PAH), which are classified as priority for different food groups by the Scientific Committee on Food (SCF) and the Joint FAO/WHO Experts Committee on Food Additives (JECFA) in tea, a sensitive analytical Fast-GC/HRMS method was used. The sample preparation included accelerated solvent extraction (ASE) and the highly automated clean up steps, gel permeation chromatography and solid phase extraction. The analytical parameters, limit of detection (0.01–0.02 μg/kg) and limit of quantification (0.03–0.06 μg/kg), were determined. The repeatability (RSD, n = 3) of different PAH in fruit tea ranged from 0.1 to 11%. It was observed that the total contents of the 16 PAH in tea samples ranged from 14 to 2,662 μg/kg. The analysed tea samples showed an increasing presence of PAH in the following order: herbal and fruit tea (n = 7) < black tea (n = 11) < green tea (n = 11) < white tea (n = 3) < mate-tea (n = 8). The correlation coefficient (R) between BaP and the sum of the 16 EFSA-PAH was established considering the contamination amount in all the 40 tea samples analysed. | Both polycyclic aromatic hydrocarbons (PAHs) and legacy organochlorine insecticides (OCPs), including DDT, are dangerous chemical contaminants. The aims of this study were to (i) determine background levels of PAHs and legacy OCPs for wheat samples collected in 2017 and 2018 in Poland, (ii) identify differences between levels in wheat harvested in various regions of Poland, (iii) evaluate differences in contamination sources manifested by the profiles of the identified chemicals, (iv) identify possible correlations between different classes of chemicals present in wheat, and (v) assess the health risks associated with the presence of PAHs and OCPs in Polish wheat. Average concentrations found in the samples were 0.09 ± 0.03 μg kg−1 for benzo[a]pyrene (BaP) (formerly used as a single PAH marker), 0.43 ± 0.16 for the more recently introduced collective PAH 4 marker (benzo[a]anthracene + benzo[a]pyrene + chrysene + benzo[b]fluoranthene), and 1.07 ± 0.68 μg kg−1 for DDT and its metabolites. The PAH profiles indicated contamination from combustion-related emission sources (liquid fossil fuels, coal, biomass). Health risks associated with the presence of PAHs and OCPs in cereals were assessed using the margin of exposure (MOE) approach. The MOE values calculated based on the highest concentrations found in this study exceeded 50,000 for both BaP and PAH 4. The calculated worst-case scenario value for DDT and metabolites was as low as 0.3% of the respective tolerable daily intake (TDI) value. Assessment of dietary risk has shown that the presence of the two contaminant classes in Polish wheat grains is of low concern. | Background Measuring the brain’s response to transcranial magnetic stimulation (TMS) with electroencephalography (EEG) offers a unique insight into the local cortical circuits and networks activated following stimulation, particularly in non-motor regions where less is known about TMS physiology. However, the mechanisms underlying TMS-evoked EEG potentials (TEPs) remain largely unknown. Objective We assessed TEP reliability, site-specificity, and sensitivity to changes in excitatory neurotransmission mediated by n-methyl-d-aspartate (NMDA) receptors following stimulation of non-motor regions. Methods In fourteen male volunteers, resting EEG and TEPs from prefrontal (PFC) and parietal (PAR) cortex were measured before and after administration of either dextromethorphan (an NMDA receptor antagonist) or placebo across two sessions separated by at least a week in a double-blinded pseudo-randomised crossover design. Results At baseline, TEPs showed lower within-than between-subject variability for both stimulation sites across sessions, demonstrating the reliability of non-motor TEPs within individuals. There were differences in amplitude between PFC and PAR TEPs across a wide time range (15-250 ms), however the signals were correlated after ∼80 ms, suggesting that early peaks reflect site-specific activity, whereas later peaks reflect global activity patterns independent of stimulation site. TEPs were not altered following dextromethorphan compared to placebo, however low frequency resting oscillations were reduced in power. Conclusions Our findings suggest that TEPs from PFC and PAR: 1) are reliable within and variable between individuals; 2) reflect stimulation site specific activity across early (<80 ms), but not late time points; and 3) are not sensitive to changes in NMDA receptor-mediated neurotransmission. | eng_Latn | 27,210 |
A fully automated HPLC method for analysing the non-ionic X-ray contrast agent iodixanol in plasma samples, using on-line dialysis for sample preparation, was developed. Optimal conditions were obtained with a static dialysis donor solution of 110 microl and 4 ml of recipient solution (dialysate) pulsed onto a trace enrichment column, giving maximum 55% dialysis efficiency in less than the chromatographic run time of 20 min. Hence, one sample could be dialysed during the analysis of the previous. The maximum load of iodixanol on the trace enrichment column was 3.75 mg. Validation showed that the method was selective for iodixanol, sensitive down to 84 pmol/ml and had a high precision over a linear range up to 320 nmol/ml. Although developed for iodixanol, the method can easily be modified and applied to other substances with similar properties, i.e., substances having low protein binding and high water solubility, but strong enough stationary phase affinity to be retained by an appropriate trace enrichment column. | This work reports a simple isocratic hydrophilic interaction liquid chromatographic (HILIC) method for the simultaneous quantification of iodixanol and of its related impurities C, D and E in drug substance. The chromatographic separation was carried out with a Kinetex™ HILIC column, using acetonitrile and formic acid aqueous solution (1.0mmol/L, pH 3.2) (92:08, v/v) as eluent at a flow rate of 0.8mL/min. The autosampler and column temperature were maintained at 20°C and UV detection was set at 243nm. The method was validated in accordance to the ICH guideline and employed for the analysis of two different lots of iodixanol drug substance. The developed method is presented as a valuable alternative to the current methods described in the USP monograph. | To estimate the glomerular filtration rate (GFR) in horses, an optimum dose of the nonionic contrast medium iodixanol as a tracer was assessed with blood-sample times. Iodixanol was administered intravenously at 10-40 mg I/kg to geldings and mares, and blood was collected 30, 60, 90, 120, 150, and 180 min later. Serum iodixanol concentration was determined by high-performance liquid chromatography (HPLC), and serum urea nitrogen (UN) and creatinine concentrations were also measured. The combination of 20 mg I/kg iodixanol and sampling times of 60, 90, and 120 min after injection was considered to be appropriate for practical use. In clinically healthy horses, the reference values were determined to be 1.90 ± 0.03 ml/min/kg (150.8 ± 2.94 ml/min/m2), consistent with historical data using different tracers. The result suggests that serum clearance of iodixanol is a ready-to-use tool for a screening of alterations in the equine GFR, although it is necessary to perform a more longitudinal study using horses with a variety of renal functions. | eng_Latn | 27,211 |
Busulfan is used in preparative regimens for bone marrow transplantation and timely busulfan plasma concentration reporting is critical for subsequent dose adjustment. We compared two sensitive methods for pharmacokinetics studies including LC-MS assay and HPLC precolumn derivatization assay. Chromatographic separation was performed on a Gemini C18 column. Liquid-liquid extraction with ethyl acetate was used for plasma sample preparation. Busulfan and internal standard ([2H8]-busulfan) were detected as ammonium adducts at m/z 264.2 and 272.2 for LC-MS assay. For HPLC assay, the extraction from plasma was derivatized with 2-naphathalenethiol using synthesized internal standard (1,6-(methanesulfonyloxy)octane). The Ex and Em wavelength was 255 nm and 370 nm. The limit of detection was 15.6 ng/mL and 7.8 ng/mL for HPLC and LC-MS assay and good linearity ranging from 31.25–1000 ng/mL for HPLC and 15.6-1000 ng/mL for LC-MS assay. The intra and interday assay precision were less than 9.2% and 12.0% for LC-MS and HPLC assay. The pharmacokinetic parameters were estimated using noncompartmental pharmacokinetic model with WinNonlin. Busulfan AUClast showed an average difference of 0.7% between the two methods. The LC-MS method is accurate, reproducible, and requires less specimen, sample preparation and analysis time over the HPLC assay, making busulfan monitoring faster and easier in clinical practice. | A high-performance liquid chromatographic (HPLC) method was developed and validated for the determination of busulfan in plasma. Busulfan was extracted in toluene, derivatized by 2,3,5,6-tetrafluorothiophenol to obtain di-TFTP-butane, the derivatization product was then re-extracted in toluene and injected into the HPLC system with ultraviolet detection (wavelength: 275 nm). Recovery from extraction was 80%, the limit of quantification was 50 ng/ml and linearity ranged from 50 to 2000 ng/ml. In addition, forty-two samples obtained from pediatric patients treated with busulfan were analyzed by the HPLC and GC-MS assays based on the same derivatization procedure. The correlation between the di-TFTP-butane concentrations was highly significant (p<0.0001), demonstrating that the two methods were in good agreement. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,212 |
A dispersive liquid–liquid microextraction (DLLME) method coupled to high-performance liquid chromatography was developed for the analysis of α-tocopherol in grain samples. The DLLME parameters including the type and volume of extractants, the volume of disperser and the addition of salt were examined. The optimized DLLME procedure consisted in the formation of a cloudy solution promoted by the fast addition to the sample (5 mL of saponified sample solution diluted with 5 mL of water) of a mixture of carbon tetrachloride (extraction solvent, 80 μL) and ethanol (dispersive solvent, 200 μL) without the addition of salt, followed by shaking for 5 min and centrifuging for 3 min at 5,000 rpm. Intra- and inter-day repeatability expressed as % RSD were 3.5 and 7.6 %, respectively. The limit of detection and the limit of quantification were 1.9 and 6.3 μg L−1. The comparison of this method with the national standardized extraction method, supercritical carbon dioxide extraction, accelerated solvent extraction, and conventional heat-reflux extraction indicates that the DLLME was accurate (no significant differences at the 0.05 % probability level), high efficient, low organic solvent-consuming, and low cost. This procedure was successfully applied to 42 samples of 14 types of purple wheat, for which the content of α-tocopherol exhibited a significantly negative correlation with the pigment content measured by a spectrophotometer. The recovery rates ranged from 90.5 to 103.7 %. | Developing a simple and fast method for quantification of vitamins in complex matrixes is one of the important issues in quality control of foods such as milk. In this study, after introducing a new method for quantification of vitamin E in infant formula, its content was compared to the label claims. In this study, dispersive liquid-liquid microextraction (DLLME) procedure with acetonitrile and chloroform as dispersive and extraction solvents, respectively, was used for isolation and clean-up of vitamin E from infant formula samples without the need for saponification. Then, reversed-phase high-performance liquid chromatography (RP-HPLC) composed of a C18 column as stationary phase and the mixture of acetonitrile, methanol, and water (91:8:1%) as mobile phase using a standard addition method was employed for quantification of vitamin E (α-tocopheryl acetate) with UV detection at 296 nm. After method validation under the optimum conditions, the method provided a linear range with a determination coefficient (R2) of 0.99 and acceptable accuracy and precision. Results showed that the developed method is an appropriate method for quality control of infant formulas. The advantage of DLLME compared with saponification process and liquid-liquid extraction is the decrease of organic solvent consumption and proposing of a simple and fast method for analysis of vitamin E in infant formula. Application of the developed method for analysis of vitamin E in infant formulas on the market showed there was a considerable difference between labeled and obtained content in most of the samples. | Developing a simple and fast method for quantification of vitamins in complex matrixes is one of the important issues in quality control of foods such as milk. In this study, after introducing a new method for quantification of vitamin E in infant formula, its content was compared to the label claims. In this study, dispersive liquid-liquid microextraction (DLLME) procedure with acetonitrile and chloroform as dispersive and extraction solvents, respectively, was used for isolation and clean-up of vitamin E from infant formula samples without the need for saponification. Then, reversed-phase high-performance liquid chromatography (RP-HPLC) composed of a C18 column as stationary phase and the mixture of acetonitrile, methanol, and water (91:8:1%) as mobile phase using a standard addition method was employed for quantification of vitamin E (α-tocopheryl acetate) with UV detection at 296 nm. After method validation under the optimum conditions, the method provided a linear range with a determination coefficient (R2) of 0.99 and acceptable accuracy and precision. Results showed that the developed method is an appropriate method for quality control of infant formulas. The advantage of DLLME compared with saponification process and liquid-liquid extraction is the decrease of organic solvent consumption and proposing of a simple and fast method for analysis of vitamin E in infant formula. Application of the developed method for analysis of vitamin E in infant formulas on the market showed there was a considerable difference between labeled and obtained content in most of the samples. | eng_Latn | 27,213 |
A method has been developed for determination of (ultra)trace amounts of As(III) and As(V) in water by flow injection on-line sorption preconcentration and separation coupled with inductively coupled plasma mass spectrometry (ICPMS) using a knotted reactor (KR). The determination of As(III) was achieved by selective formation of the As(III)-pyrrolidine dithiocarbamate complex over a sample acidity range of 0.01-0.7 mol L-1 HNO3, its adsorption onto the inner walls of the KR made from 150-cm-long, 0.5-mm-i.d. PTFE tubing, elution with 1 mol L-1 HNO3, and detection by ICPMS. Total inorganic arsenic was determined after prereduction of As(V) to As(III) in a 1% (m/v) L-cysteine-0.03 mol L-1 HNO3 media. The concentration of As(V) was calculated by difference (the total inorganic arsenic and As(III)). Owing to the group-specific character of the chelating agent, and the use of an efficient rinsing step before elution, the interferences encountered in conventional ICPMS from common major matrix, alkali and alkaline earth metals, and chlorides were eliminated. The presence of organoarsenic species such as monomethylarsonate and dimethylarsinate in water samples had no effect on the results of As(III) and As(V). Thus, the method can be applied to the speciation analysis of inorganic arsenic at submicrogram per liter levels in aqueous solutions with high total content of dissolved solid and/or high content of chlorides. Using a preconcentration time of 60 s and a sample flow rate of 5 mL min-1, an enhancement factor of 22 was achieved in comparison with conventional ICPMS. The time required for a single determination was 200 s. The detection limits (3s) was evaluated to be 0.021 microgram L-1 for As(III) and 0.029 microgram L-1 for total inorganic arsenic. The precision for 14 replicate determinations of 1 microgram L-1 As(III) was 2.8% (RSD) with drift correction and 3.9% (RSD) without drift correction. The concentrations of As(III) and As(V) in synthetic mixtures obtained by the present method were in good agreement with expected values. Results obtained by the proposed method for total arsenic in a river water reference material agreed well with certified and recently reevaluated values. The method was also applied to the speciation analysis of inorganic arsenic in porewaters. | In natural environment, Arsenic (As) occurs in four oxidation states, namely, As(V), As(III), As(0), and As(−III). The oxidation state of As determines its toxicity and mobility in the environment. Thus, quantification and speciation of As are critical in assessing the overall risk. Further, As being a class A carcinogen, it is of interest to both environmental scientists and analytical chemists. Thus, sensitive and adept determination of As and speciation of different forms of As in various environmental matrices are indispensable. Most of the countries around the world have relevant official regulations on permissible levels of As in drinking water. In India, the permissible limit of As in drinking water is set at 10 µg/L by Bureau of Indian Standards (BIS) and WHO guideline value is also 10 µg/L. In this review, we focus on extraction of As from various environmental samples, As speciation, sample treatment, and determination of As in various matrices. Analytical methods for the determination of various forms of As like atomic absorption spectrophotometer (AAS), hydride generation AAS (HG_AAS), atomic fluorescence spectrometry (AFS), inductively coupled mass spectrometry (ICPMS), electrochemical methods, capillary electrophoresis (CE), high-performance liquid chromatography (HPLC), HPLC coupled with mass spectrometer (HPLC-MS), neutron activation analysis, and biosensors are also summarized. Determination of As in the field using various field test kits available in the market is also detailed. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 27,214 |
The ageing processes of nuclear glasses under irradiation have been simulated on three simple glass compositions (4-, 5- and 6-oxide glasses) by external β-irradiation. The structure of these glasses has been studied by Raman spectroscopy, and all three exhibit similar evolution under irradiation. The main findings are: (i) an increase of the network polymerization relative to the non-irradiated samples, (ii) an increase in concentration of molecular O 2 and (iii) a decrease of the average Si–O–Si bond angle. These data confirm the structural effects of the migration of sodium ions under external irradiation. | Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin and constitutes a potential health threat to humans and livestock. This study aimed to explore the potential of albite modified by the cationic surfactant cetylpyridinium chloride (CPC) as ZEN adsorbent. The organoalbite (OA) was characterized by SEM analysis, XRD analysis, FTIR spectroscopy, thermal analysis, and BET gas sorption measurement. In vitro adsorption of ZEN by OA was carried out by simulating the pH conditions of the gastrointestinal tract. The characterization results showed that the surface of OA changed from hydrophilic to hydrophobic after modification. Adsorption kinetic studies showed that ZEN adsorption behavior of OA occurred by chemisorption. The equilibrium adsorption data fitted well with the Langmuir isotherm, indicating that the adsorption process of ZEN by OA was monolayer. The maximum adsorption capacity (qm) values of OA for ZEN were 10.580 and 9.287 mg/g at pH 7 and pH 3, respectively. In addition, OA had a low desorption rate (about 2%), and co-existing amino acids (i.e., Lys and Met), vitamins (i.e., VB1 and VE), and minerals (i.e., Fe2+ and Ca2+) did not affect the removal of ZEN. These results demonstrate that OA could be a promising mycotoxin adsorbent for removing the hydrophobic, weakly polar ZEN. | The effect of preoperative radiation therapy on the pseudocapsule of experimental rat soft-tissue sarcomas has not been histologically evaluated in a controlled study. The irradiated animal showed marked thickening of the capsular structure surrounding the sarcoma. Everywhere morphologically distinct from the tumor, there was no evidence of tumor invasion into or through this capsular structure. The membrane was consistently thicker and more hyalinized than in the control animals. The nonirradiated animals showed a minimal pseudocapsular structure with a characteristic tumor penetration. Irradiation produced distinct histologic changes in the pseudocapsule. Although assumed on the basis of clinical observations alone, irradiation-induced pseudocapsule has not previously been demonstrated in an experimental model of soft-tissue sarcoma. | eng_Latn | 27,215 |
We have extended the hyperspherical variables method to the analytical calculation of the angular integral of the box graph. We discuss the applications of our results to the analytical calculation of the QED contribution to the electron g-2 of the set of three-loop triple-cross vertex graphs. | The Standard Model prediction for $\mu$-$e$ scattering at Next-to-Next-to-Leading Order (NNLO) contains non-perturbative QCD contributions given by diagrams with a hadronic vacuum polarization insertion in the photon propagator. By taking advantage of the hyperspherical integration method, we show that the subset of hadronic NNLO corrections where the vacuum polarization appears inside a loop, the irreducible diagrams, can be calculated employing the hadronic vacuum polarization in the space-like region, without making use of the $R$ ratio and time-like data. We present the analytic expressions of the kernels necessary to evaluate numerically the two types of irreducible diagrams: the two-loop vertex and box corrections. As a cross check, we evaluate these corrections numerically and we compare them with the results given by the traditional dispersive approach and with analytic two-loop vertex results in QED. | In South Africa, indigenous herbal teas are enjoyed due to their distinct taste and aroma. The acclaimed health benefits of herbal teas include the management of chronic diseases such as hypertension and diabetes. Quality control of herbal teas has become important due to the availability of different brands of varying quality and the production of tea blends. The potential of hyperspectral imaging as a rapid quality control method for herbal tea blends from rooibos (Aspalathus linearis), honeybush (Cyclopia intermedia), buchu (Agathosma Betulina) and cancerbush (Sutherlandia frutescens) was investigated. Hyperspectral images of raw materials and intact tea bags were acquired using a sisuChema shortwave infrared (SWIR) hyperspectral pushbroom imaging system (920–2514 nm). Principal component analysis (PCA) plots showed clear discrimination between raw materials. Partial least squares discriminant analysis (PLS-DA) models correctly predicted the raw material constituents of each blend and accurately determined the relative proportions. The results were corroborated independently using ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS). This study demonstrated the application of hyperspectral imaging coupled with chemometric modelling as a reliable, rapid and non-destructive quality control method for authenticating herbal tea blends and to determine relative proportions in a tea bag. | eng_Latn | 27,216 |
Background Trituration of base substances, commonly to the 3cH level, is the cornerstone of the homeopathic pharmaceutical process or insoluble solutions. 1 Becker and Ehrler claim that trituration to 4cH gives a new, spiritual dimension to the homoeopathic medicine picture. 2 Aim and method This study sought to establish whether the claim that C4-derived potencies possess different physicochemical qualities to the homoeopathic medicines derived from a 3cH trituration is valid. All potencies were produced by hand according to the German Homoeopathic Pharmacopoeia (GHP). Five different samples were analysed using Nuclear Magnetic Resonance (NMR) Spectroscopy. Results The results indicated a significant difference between the 12cH samples of potassium dichromate ( Kalium bichromicum ) produced from 3cH and 4cH triturations. This was especially prominent in the chemical shift values of all four peaks and the relative integration levels of the H 2 O, OH and CH 3 peaks when comparing two sample groups. Conclusion Trituration plays a part in the development of physicochemical properties specific to homoeopathic medicines. The higher the level of trituration, the more pronounced is the alteration of the physical structure of the active ingredient. The study concludes that 4cH potencies are physicochemically distinct from 3cH-derived potencies (as currently employed). | Background: the effects of homeopathic high dilutions (HDs) are controversial because they exceed Avogadro’s number. Aim: to perform a literature review on the effects of HDs on in vitro models. Methods: a systematic search was performed in database PubMed for studies assessing simple HDs on in vitro models published from 2007 onward. Results: 28 publications met the inclusion/exclusion criteria; 26 studies demonstrated patent effects of simple HDs on in vitro models; most such studies were conducted in countries where homeopathy attained a high level of institutionalization. Conclusions: in vitro models patently evidence biological activity of HDs above Avogadro’s number and account for effects found in clinical practice. Most studies were conducted in countries where homeopathy is officially recognized, which facilitates access to resources for the development of research. | We characterize stability under composition, inversion, and solution of ordinary differential equations for ultradifferentiable classes, and prove that all these stability properties are equivalent. | eng_Latn | 27,217 |
Hybrid organic‐inorganic particles combine the best properties of silica — high efficiency and excellent mechanical strength — with the best properties of organic polymers — a wide pH stability range and reduced silanol effects. In this article, the authors describe reversed-phase HPLC packings based on hybrid particles and demonstrate the packing’s retention and selectivity characteristics. They also show that these media have long lifetimes at elevated temperatures under conditions at which conventional bonded silica fails rapidly. The benefits of operating at elevated temperatures are increased efficiency and reduced back pressure. When combined with short columns containing 2.5- mm hybrid particles, these conditions enable fast, high-resolution gradient separations, which are useful for high-throughput analyses. | Glufosinate ammonium or ammonium salt (ammonium-(2RS)-2-amino-4- (methylphosphinato) butyric acid; C5 ::: H15N2 ::: O4 ::: P) ::: is a commonly used polar herbicide in Malaysia and present in a variety of environmental waters at the sub-ppb level. ::: Thus, glufosinate ammonium is analyzed in soil and water using high-performance liquid chromatography (HPLC), ::: which is a complex yet the most powerful analysis tool. HPLC is tremendously sensitive and highly automated and HPLC ::: instrumentation and machinery have improved over the years. However, typical problems are still encountered. HPLC ::: users and advanced learners require help in identifying, separating and correcting typical problems. All HPLC systems ::: consist of similar basic components. Although it is a modular system, trouble can occur in each component and change ::: the overall performance. Resolving these problems may be expensive. This review describes the different aspects of HPLC, ::: particularly troubleshooting, common problems and easy guidelines for maintenance. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 27,218 |
Background: The effective monitoring of antitubercular drugs, including ethambutol (EMB), is important for the control of multiple drug resistance. The development of fast, facile, and inexpensive methods for the detection of low concentrations of EMB, especially near its minimum inhibitory concentration, is also important. Results: An UPLC method for estimating EMB in rat plasma was developed and validated. The method uses a small injection volume (1 μl) and elutes EMB at 3.18 min, with 0.070 μg ml−1 and 0.250 μg ml−1 as the limits of detection and quantification, respectively. The intra- and interday accuracy was 106.01–108.82% and 107.80–109.00%, respectively, with a precision of 97% at three concentration levels, establishing the consistency and reproducibility (n = 6) of the method. EMB was found to be stable in plasma under different storage and processing conditions. Conclusion: This paper presents a highly sensitive and specific isocratic UPLC method for the rapid quantization of EMB for use in pharmacokinetics and therapeutic drug monitoring. | Objecfive:To determine the content of ethambutol hydrochloride in the combined preparation of antituberculotic.Method:An ion pair RP-HPLC method was established using C18 column (4.6 mm×150 mm,5 μm),The mobile phase was composed of 0.016% bluestone in THF-0.4% SHS (adjust pH to 4.5 with phosphoric acid) (25∶75).The flow rate was 1 mL·min-1,detection wavelength at 258 nm.Results:The linear range of ethambutol hydrochloride was 0.08-0.32 mg·mL-1,the average recovery was 99.8%.Conclusion:The method showed good separation,the results are accurate and reproducible. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,219 |
Radionuclides may be released into the environment accidentally or incidentally, which could raise health risks when ingested or inhaled by humans. In order to study the behaviour of radionuclides in the human organism (metabolism, retention, excretion), knowledge of radionuclide speciation is indispensable: speciation governs the transfer, bioavailability and toxicity of elements and is also of considerable interest for decorporation. In this context, the Commissariat a l'Energie Atomique has created a working group on speciation to share data both on thermodynamic constants and on speciation analysis methods of interest to chemists, environmentalists and biologists. The initial focus was on the 31 radionuclides described in different International Commission on Radiological Protection models (HRTM, HAT) and the National Council on Radiation Protection model (wound). Particular attention was devoted to selecting the inorganic and organic ligands, most representative of biological media. The base applied to speciation in solution and at interfaces and solubility (BASSIST) thermodynamic database was developed for this purpose. The aim of this paper is to present the state of the art on radionuclide speciation tools within biological media and to emphasise some missing data in order to orient future research. | Studies of the chemical speciation of uranium in water can enhance the knowledge of the mechanisms of its absorption from the gastrointestinal tract and its storage in the body. They can also help to improve the dosimetric models recommended by the International Commission on Radiological Protection (ICRP). The aim of this work was to assess the influence of uranium speciation on its absorption from the gastrointestinal tract by using both computer speciation modeling and direct measurement of the fractional absorption in vivo in rats after ingestion of five different samples of contaminated water. Preliminary ex vivo studies with human saliva and gastric juice showed that 90% of uranium was recovered with the natural components of the fluid studied. The computer studies of uranium speciation among the electrolytes of these fluids showed that under the set conditions, the chemical species changed in a broadly similar manner under the influence of fluid composition and pH. In vivo studies in rats validated... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,220 |
Ultrasound treatment has been widely applied in the extraction of biologically active compounds including carotenoids. However, there are few reports on their effects on the stability of these compounds. In the present study, the stability of all-trans lutein, one of the carotenoids, was investigated under the action of ultrasound. Results showed that ultrasound induced the isomerization of all-trans lutein to its isomers, namely to 13-cis lutein, 13'-cis lutein, 9-cis lutein and 9'-cis lutein as analyzed by HPLC coupled with DAD and LC-MS; and the percentage of the isomerization increased with increasing both ultrasonic frequency and power. The stability of all-trans lutein in dichloromethane was worst among multiple kinds of solvents. Interestingly, the retention rate of all-trans lutein improved as the temperature increased, which runs counter to the Arrhenius law. Under ultrasound irradiation, the degradation mechanism might be different with various temperatures, the degradation of all-trans lutein followed first-order kinetics at 20°C, while second-order kinetics was followed at 30-50°C. As the ultrasonic reaction time prolonged, lutein epoxidation nearly occurred. Those results presented here emphasized that UAE techniques should be carefully used in the extraction of all-trans lutein. | ABSTRACT The aim of this study was to investigate the influence of microwave vacuum drying on carotenoids in pumpkin (Cucurbita maxima L.) slices. Carotenoids were measured using the reverse-phase high-performance liquid chromatography technique. It was shown that compared with hot air drying, microwave vacuum drying inhibited color changes and significantly (p < 0.05) improved total carotenoid retention (89.1%) in pumpkin slices. During the microwave vacuum drying process, microwave power had an important effect on total carotenoid and all-trans carotenoids. As microwave power increased, the total carotenoid content significantly decreased (p < 0.05), and the levels of individual carotenoids, including all-trans-α-carotene, all-trans-β-carotene, and all-trans-lutein, generally decreased. However, there was an overall upward trend for the levels of 13-cis-β-carotene, 15-cis-β-carotene, 9-cis-β-carotene, and 9-cis-α-carotene. The trans carotenoid quality of the finished products was improved within a certain range of vacuum levels. In addition to the degradation induced by microwave energy, isomerization was considered to be responsible for the loss of all-trans carotenoids. These results indicated that inappropriate drying methods and conditions might result in high losses of all-trans carotenoids in pumpkins. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,221 |
The selective extraction of the minor actinides (Am(III) and Cm(III)) from the lanthanides is an important part of advanced reprocessing of spent nuclear fuel. This separation would allow the Am/Cm to be fabricated into targets and recycled to a reactor and the lanthanides to be dispositioned. This separation is difficult to accomplish due to the similarities in the chemical properties of the trivalent actinides and lanthanides. Research efforts at the Idaho National Laboratory have identified an innovative synthetic pathway yielding new regiospecific dithiophosphinic acid (DPAH) extractants. The synthesis provides DPAH derivatives that can address the issues concerning minor actinide separation and extractant stability. For this work, two new symmetric DPAH extractants have been prepared. The use of these extractants for the separation of minor actinides from lanthanides will be discussed. | Separation factors of tracer amounts of Am from micro lanthanides (La, Ce, Pr, Nd, and Sm) by purified Cyanex 301 extraction in nitrate media have been determined: SFAm/La ∼ 3500, SFAm/Ce,pr ∼ 1000, SFAm/Nd ∼ 1900, and SFAm/Sm∼ 4500, with an average value >2300. The distribution ratio decreases with increasing lanthanide concentration in the aqueous phase. In the presence of a macro amount of Pr + Nd (0.1 ∼ 0.6 M) the separation factors SFAm/Eu and SFAm/pr+Ndare about 4.7 × 103 and 2.1 × 103, respectively. The results of the countercurrent fractional process show that by using three extraction stages and two scrubbing stages, >99.99% Am can be separated from a tracer amount of Eu with 99.99% Am and <0.6% macro amount of Pr ± Nd are extracted into the organic phase. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,222 |
A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method as an alternative to a gas chromatography-thermal energy analyser (GC-TEA) method recommended by the European Committee on Standardization (CEN) was validated for the simultaneous determination of eight N-nitrosamines released into artificial saliva from rubber or elastomer teats and soothers. N-nitroso-dipropylamine-d14 (NDPA-d14) was used as internal standard for accurate quantification. The method was validated with relatively good analytical results, including sufficiently low limits of detection (0.1–2 µg kg−1 of sample) and good linearity (r 2 > 0.99) throughout the studied concentration ranges. Intra- and inter-day precisions expressed with the relative standard deviation (RSD, %) were 3.4–8.0% and 4.4–11.3%, which were below the performance criteria based on one-half of the value derived from the Horwitz value. It was also found that the LC-MS/MS method is sufficiently rugged and successfully applicable to its routine analysis for ... | Ensuring the safety of baby bottle teats and kitchen tools made from rubber is critical. Therefore, the migration of N-nitrosamines and N-nitrosatable substances from 30 teats and 45 kitchen tools to artificial saliva was analyzed by liquid chromatography–tandem mass spectrometry. The method was validated by assessing the limits of detection (0.46–3.87 μg/kg), limits of quantification (1.38–11.73 μg/kg), and recoveries (86.3–108.6%) of seven compounds. Nitrosodimethylamine (NDMA), N-nitrosopiperidine, and N-nitrosomorpholine (NMOR) migrated from baby bottle teats at concentrations of not detected (ND) to 3.67 μg/kg. NDMA and NMOR concentrations ranged from ND to 1.72 μg/kg after migration from 45 rubber kitchen tools. N-nitrosatable substances ranged from ND to 42.16 μg/kg after migration from baby bottle teats but did not migrate from rubber kitchen tools. All tested products were considered safe for use, as N-nitrosamine and N-nitrosatable substance levels did not exceed the permitted management specifications. | This paper reviews liquid chromatographic-mass spectrometric (LC-MS) procedures for the screening, identification and quantification of doping agents in urine and other biological samples and devoted to drug testing in sports. Reviewed methods published approximately within the last five years and cited in the PubMed database have been divided into groups using the same classification of the 2004 World Anti-Doping Agency (WADA) Prohibited List. Together with procedures specifically developed for anti-doping analysis, LC-MS applications used in other fields (e.g., therapeutic drug monitoring, clinical and forensic toxicology, and detection of drugs illicitly used in livestock production) have been included when considered as potentially extensible to doping control. Information on the reasons for potential abuse by athletes, on the requirements established by WADA for analysis, and on the WADA rules for the interpretation of analytical findings are provided for the different classes of drugs. | eng_Latn | 27,223 |
The present study was undertaken for the effect of spirulina on biochemical parameters and reduction of tissue arsenic concentration in arsenic induced toxicities in ducks. One hundred and seventy 5 ducklings were divided into five equal groups separately. One group (T ) of ducklings was kept as control. 0 One group (T ) of ducklings were given arsenic trioxide @ 100 mg/L drinking water and rest three groups of 1 ducklings (T , T and T ) were given arsenic trioxide @ 100 mg/L plus spirulina in three different doses i.e. 2 3 4 30, 60 and 120 mg/L in drinking water daily for 90 days starting from day 15. Five birds were sacrificed from each group in every 15 day intervals and biochemical parameters were determined. All the biochemical parameters (SGPT, SGOT, ALP, LDH and ACP) were significantly (p<0.01) elevated in arsenic treated groups. However, the elevation of these parameters was less in arsenic plus spirulina treated groups (T , T and T ). 2 3 4 The distribution of arsenic concentration was highest in liver and lowest in faeces. Maximum reduction of arsenic was recorded in all organs following highest doses of spirulina (120 mg/L). The present study reveals that spirulina may be helpful for reducing the tissue burden of arsenic in ducks. | Arsenic compounds have been used extensively in agriculture in the US for applications ranging from cotton herbicides to animal feed supplements. Roxarsone (3-nitro-4-hydroxyphenylarsonic acid), in particular, is used widely in poultry production to control coccidial intestinal parasites. It is excreted unchanged in the manure and introduced into the environment when litter is applied to farmland as fertilizer. Although the toxicity of roxarsone is less than that of inorganic arsenic, roxarsone can degrade, biotically and abiotically, to produce more toxic inorganic forms of arsenic, such as arsenite and arsenate. Experiments were conducted on aqueous litter leachates to test the stability of roxarsone under different conditions. Laboratory experiments have shown that arsenite can be cleaved photolytically from the roxarsone moiety at pH 4-8 and that the degradation rate increases with increasing pH. Furthermore, the rate of photodegradation increases with nitrate and natural organic matter concentration, reactants that are commonly found in poultry-litter-water leachates. Additional photochemical reactions rapidly oxidize the cleaved arsenite to arsenate. The formation of arsenate is not entirely undesirable, because it is less mobile in soil systems and less toxic than arsenite. A possible mechanism for the degradation of roxarsone in poultry litter leachates is proposed. The results suggest that poultry litter storage and field application practices could affect the degradation of roxarsone and subsequent mobilization of inorganic arsenic species. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 27,224 |
OBJECTIVE: To evaluate the relationship between pelvic organ prolapse in Korean women and joint hypermobility, which suggests a metabolic collagen fiber abnormality. STUDY DESIGN: Between March 1998 and March 2000, we investigated 55 patients with prolapse. The prevalence of joint hypermobility, by measuring finger extension angle, and the provortion of patients with joint hypermobility were measured in patients with pelvic organ prolapse and benign gynecologic patients (control group). RESULTS: In middle-aged women (40-59 years), the average finger extension angles were higher in the POP group than in the control group (50.04 ± 9.70° vs. 39.50 ± 12.19°, respectively; P .05). CONCLUSION: The prevalence of joint hypermobility was higher in the POP group and with advanced POP stage (III, IV) than in the control group and early POP stage (I, II). Our results suggest that intrinsic connective tissue abnormality is related to the development of pelvic organ prolapse. Further study involving more patients with pelvic organ prolapse is warranted, and molecular studies to determine the genetic basis of pelvic organ prolapse are also required to further elucidate this abnormality. | Introduction and hypothesis ::: Abnormalities of common collagen proteins have been noted in individuals affected by POP and JHM, suggesting a common aetiology. We assessed strength, consistency and potential for bias in pooled associations of the relationship between JHM and POP. | The uptake of Eu3+ (a trivalent actinide homolog) by Aldrich humic acid covalently bonded to an inorganic support is examined. Two types of covalent linkages are used and the synthetic routes to produce the resins are discussed. The use of these resins excludes having to account for humic acid desorption from the surface, yields a well characterized system, and allows the experiment to focus on and account for the role of humic acid in the sorption of Eu. The proton exchange capacity of the resins is examined by titration and the differences observed are traced to the resin synthesis. Europium sorption experiments are performed at pH 4 and pH 6 in 0.1 M NaClO4. Kinetic experiments show equilibrium is reached in 24 hours. The kinetic data are used to evaluate the loading capacity, with results similar to equilibrium experiments. The complexation results are evaluated based on the metal ion charge neutralization model. For the resins an effect of pH and resin synthesis route on the Eu uptake is observed. The uptake increases with pH for both resins. The resin HA-Epo (Epoxy linkage) has a higher metal binding at pH 4, while the resin HA-HAB (2-hydroxylazobenzene linkage) had more proton exchange sites occupied by metal ions at pH 6. Overall, more Eu is bound to HA-Epo at pH 6 since its proton exchange capacity is higher. The evaluated stability constants vary slightly and show a dependence on the linkage group but are similar to literature values that examined complexation by aquatic humic acid analyzed with the same model. This result supports the utility of the metal ion charge neutralization model and the applicability of the resulting stability constants. | eng_Latn | 27,225 |
The cosmic-ray spallation of atmospheric argon produces a unique group of radionuclides with half-lives ranging from minutes to millions of years. Depending on their physical characteristics, these radionuclides may either become attached to the atmospheric aerosol and thus serve as a tracer of its subsequent behavior, or may behave as a gas and follow precisely the prevailing air motions. To provide a more precise basis for the use of the short-lived radionuclides as tracers of short-term atmospheric mixing and precipitation processes, the atmospheric concentrations of 38Cl (37 min), 39Cl (55 min), and 24Na (15 hours) and some longer-lived radionuclides have been measured at altitudes through 19 km and over a considerable range of latitudes. The observed concentration gradients are described, and the apparent relative production rates are compared with theoretical calculations and with some cosmic-ray production rates in argon. | Extant data from measurements of halogens in the atmosphere are reviewed in the following categories: gaseous chlorine compounds (inorganic and organic), particulate chloride and chloride in precipitation, gaseous bromine compounds (inorganic and organic), particulate bromide and bromide in precipitation, gaseous iodine compounds (inorganic and organic), iodine in particles and in precipitation, gaseous fluorine compounds (inorganic and organic), and fluoride in particles and precipitation. The roles that these data and other unavailable data play in defining global cycles of the halogens are discussed. Speciation of the halogen gases in the troposphere is very uncertain: the only inorganic species detected by species‐specific methods are HCl and SF6. More specific data are available on organic forms that contain halogens. Key species of gaseous halogens, either established or suspected to be important, are listed along with key processes that need investigation. Heterogeneous reactions, both gas‐to‐particle and particle‐to‐gas processes, precipitation removal, and sea‐salt aerosol generation and fractionation processes need quantitative investigation to allow progress in estimating halogen sources and sinks. Where practical, as with stratospheric inorganic chlorine gases, quantitative comparisons are made between measured and predicted concentrations. Copyright © 1981 by the American Geophysical Union. | Since the early 1980s the usefulness of dietary beta-agonists to improve the efficiency of feed utilization and(or) to enhance carcass leanness in livestock species has been well documented. Less well documented are the pharmacokinetic properties, biotransformation pathways, and tissue residue profiles of beta-agonists used to enhance leanness in experimentally or illegally treated animals. Pharmacokinetic data for clenbuterol, cimaterol, fenoterol, L-644,969, ractopamine, salbutamol, and terbutaline have been published but biotransformation and tissue residue studies for these compounds in livestock species are sparse. In general, beta-agonists having halogenated aromatic ring systems are metabolized by oxidative and conjugative pathways and have long plasma half-lives, whereas beta-agonists having hydroxylated aromatic rings are metabolized solely by conjugation and have relatively short plasma half-lives. Beta-Agonists having high oral bioavailabilities, long plasma half-lives, and relatively slow rates of elimination have high oral potencies in humans. Residues of such illegally used compounds in edible tissues of livestock represent a genuine risk to consumers. Conversely, beta-agonists having low oral bioavailabilities, short plasma half-lives, and rapid rates of elimination have low oral potencies in humans. Residues of such compounds in edible tissues of properly treated animals would not likely represent a credible risk to consumers of such products. The reviewed data indicate that the development of a safe and effective beta-agonist for use in livestock is possible. | eng_Latn | 27,226 |
A rapid, sensitive method for evaluating antioxidants is described. The antioxidant comparisons are based on minimizing β-carotene loss in an emulsified, aqueous, coupled oxidation of linoleic acid and β-carotene. The effects of linoleic acid levels were observed. Attempts to replace β-carotene with vitamin A or linoleic acid with ergosterol gave undesired results. The quantitative applications of the method are discussed. | The available data about the interference of oxidation compounds in the oxidation kinetics of process such as lipid oxidation chain reactions, the resistance of pharmaceutical drugs, the effects of free radical agents in cell tissue, the damage caused in DNA, etc, are examples of the many applications for in vivo and in vitro assays. However, often in these bio-assays, only semi-quantitative conclusions can be obtained, due to the use of quantification procedures disregarding kinetic considerations. A pseudo-mechanistic model is proposed which is based on the accumulative Weibull's function, and represents a formal transfer from the field of the dose-response relationships. It allows researchers to obtain the simultaneous solution of a series of oxidation activities as a function of concentration and time. It describes satisfactorily simulations in which reaction compounds interact through a second order kinetic scheme. Its application is simple: it provides parametric estimates, which characterize the oxidative process; facilitates rigorous comparisons between the effects of distinct compounds in different systems; reduces the sensitivity to the experimental error; and its mathematical form constitutes a useful orientation to prepare more economic and efficient trial designs. The model was assayed, firstly, using the kinetic simulation of the oxidative process, and finally, it was applied to a variety of experimental data from other authors in different systems and conditions, obtaining highly satisfactory results in all cases. In all experimental data tested, the calculated parameters were always statistically significant (Student's t-test, α = 0.05), the equations were consistent (Fisher's F-test) and the goodness of fit (adj R 2 , adjusted coefficient of multiple determination) were up to 0.98. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,227 |
A reversed-phase high-performance liquid chromatographic method with tandem mass-spectrometric detection was developed and validated for the simultaneous analysis of eight quinolones and fluoroquinolones (oxolinic acid, flumequine, piromidic acid, enrofloxacin, ciprofloxacin, danofloxacin, sarafloxacin and orbifloxacin) in trout tissue, prawns and abalone. The analytes were extracted from homogenised tissue using acetonitrile and the extracts subjected to an automated two-stage solid-phase extraction process involving polymeric reversed-phase and anion-exchange cartridges. Good recoveries were obtained for all analytes and the limit of quantification was 5 μg/kg (10 μg/kg for ciprofloxacin). The limit of detection was 1–3 μg/kg, depending on the analyte and matrix. Confirmation of the identity of a residue was achieved by further tandem mass-spectrometric analysis. A procedure for estimating the uncertainty associated with the measurement is presented. | This paper describes the development of a specific ultra performance LC with electrospray ionization tandem mass spectrometric method for simultaneous determination of 13 quinolones in livestock and fishery products. The procedures involve the sample preparation based on solvent extraction without further clean up procedure. The method was validated according to the FDA guidelines. The limit of detection (LOD) and quantification (LOQ) were lower than 0.1 and 0.4 μg/kg, respectively, and these were below the maximum residue limits (MRLs) established by European Union. Recoveries ranged from 87.5 to 104.7% for livestock products and 83.0 to 100.9% for fishery products. Relative standard deviations (RSD) ranged from 0.4 to 6.0% and 0.9 to 5.7%, respectively. The method was successfully applied to the analysis of quinolones residue. This quantitative method has many advantages including simple preparation, rapid determination, and high sensitivity, which could be applied to the determination of quinolones residues in foodstuff. | By using a superluminescent diode as the light source and a depolariser inside the fibre coil, a constant scale factor is achieved without using polarisation control elements. For long-term behaviour an RMS-bias drift of 10 degrees/h is obtained. | eng_Latn | 27,228 |
The ages of three species of cetaceans were estimated by counting the growth layer groups (GLG) and measuring the aspartic acid racemization rate ( k Asp ) by what is referred to as the Aspartic Acid Racemization (AAR) technique. Data on k Asp and the D/L ratio of aspartic acid at birth [(D/L) 0 ] in North Atlantic common minke whales ( Balaenoptera acutorostrata ) are presented along with data on fin whales ( B. physalus ) and harbour porpoises ( Phocoena phocoena ) already published by Nielsen et al. (2012). The k Asp specific for minke whales was 1.40 x 10 -3 yr -1 (SE ± 0.00005) and the (D/L) 0 was 0.0194 (SE ± 0.0012). The correlation of GLG age and D/L ratio for all three species was highly significant; however, the correlation coefficient varied greatly (fin whales: R 2 = 0.59, p <0.0001; minke whales: R 2 =0.96, P <0.0001; harbour porpoises: R 2 =0.36, P <0.0001). Asymptotic body length for all three species was estimated by a von Bertalanffy growth model on both the GLG and AAR techniques, and showed no difference. | PURPOSE ::: To examine the relationship of ocular components to refraction throughout the adult life span of the rhesus monkey (Macaca mulatta). ::: ::: ::: METHODS ::: Cycloplegic retinoscopy, A-scan ultrasonography, slit lamp examination, indirect ophthalmoscopy, and keratometry were performed in a cross-sectional study of 111 monkeys, aged 5 to 31 years. Lens thickness and anterior and vitreous chamber depths were measured from the echograms. The intercorrelations of these variables were analyzed, as well as their association with age and sex. ::: ::: ::: RESULTS ::: In monkeys aged 5 to 15 years, the mean refractive value of +1.5 D with an SD of 1.7 D was maintained near the previously established developmental asymptote of +2 D. In monkeys older than 15 years, there was greater interindividual variation (SD = 4.5 D), including extreme myopia and hyperopia. The cornea became steeper with age. The axial length of the eyes increased up to 12 years of age and began to shorten after 20 years. Changes also occurred in the other individual components that constitute eye length. These age-related changes were decreased vitreous chamber depth, decreased anterior chamber depth, and increased lens thickness. In general, males had longer eyes than females. The eyes of old monkeys were more likely to exhibit cataract and drusen, but age-related changes in focal atrophy of the retinal pigment epithelium did not achieve statistical significance. ::: ::: ::: CONCLUSIONS ::: The components of the monkey eye change with age in a pattern similar to that reported in humans. Age-related changes in individual ocular components that could be detrimental to refraction appear to be compensated for by changes in other components. | Fluorous tagging strategy is applied to solution-phase parallel synthesis of a library containing hydantoin and thiohydantoin analogs. Two perfluoroalkyl (Rf)-tagged α-amino esters each react with six aromatic aldehydes under reductive amination conditions. Twelve amino esters then each react with 10 isocyanates and isothiocyanates in parallel. The resulting 120 ureas and thioureas undergo spontaneous cyclization to form the corresponding hydantoins and thiohydantoins. The intermediate and final product purifications are performed with solid-phase extraction (SPE) over FluoroFlashTM cartridges, no chromatography is required. Using standard instruments and straightforward SPE technique, one chemist accomplished the 120-member library synthesis in less than five working days, including starting material synthesis and product analysis. | eng_Latn | 27,229 |
Several analytical methods were developed to determine cypermethrin and its acid metabolite residues in bovine milk, cream, kidney, liver, muscle, and fat samples. These methods used solvent extraction or acid reflux, liquid−liquid and/or solid phase extraction, with or without chemical derivatization, and quantitation by gas chromatograph with electron capture or mass selective detector. The LOQ and LOD for milk were set at 10 and 2 ppb, respectively. The average method recoveries for cypermethrin, cis-DCVA, trans-DCVA, and m-PBA in cow milk were 81% (n = 39), 96% (n = 22), 99% (n = 22), and 106% (n = 22), respectively. For bovine tissues and cream samples, the LOQ and LOD were 50 and 10 ppb, respectively. The overall average method recoveries for cypermethrin, cis-DCVA, trans-DCVA, and m-PBA in cream and tissue samples were 92% (n = 27), 97% (n = 25), 103% (n = 25), and 98% (n = 25), respectively. Satisfactory recoveries were also obtained with higher fortification levels for milk and fat samples. Keywo... | Beta-cypermethrin (BCYP), a synthetic pyrethriod (PYR) pesticide which is a mixture of the alpha- and theta- cypermethrin, have been reported various toxicological profiles to non-target organisms. But little is known about assimilation, accumulation and toxic effects of BCYP in reptiles. The present study firstly elucidated absorption, tissue distribution, excretion of BCYP in Eremias argus . Treated group were administered orally with BCYP 20mg/kg body weight (bw) dissolved in corn oil. Neurotoxicity was observed at 24h after gavage, and the poisoning symptom ameliorated at 72h. The changes of BCYP concentration depended on degradation time and tissues. Lizards had a strong capacity to eliminate BCYP with different tissue distribution. The tissues concentration of BCYP from high to low were intestine, stomach, heart, kidney, blood, lung, liver and brain. Bimodal phenomena were observed in lung, liver and kidney. These results may be due to the activities of enzymes, circadian rhythm, and enterohepatic circulation in lizards. Based on the results of organ coefficient and histopathology analysis in liver, the liver was confirmed as the main target organ. | Efficient laser-diode pumped Cr, Yb:YAG self-Q-switched laser by bonding Yb:YAG crystal to enhance inversion population have been demonstrated for the first time. Average output power of 1 W and optical-to-optical efficiency of 18.5% have been achieved. | eng_Latn | 27,230 |
Summary: In spite of recent developments, the global analysis of membrane subproteomes is still a common obstacle. In this work we explore whether quantification of mitochondrial membrane proteins can be achieved by SDS-PAGE separation followed by in-gel digestion, 16 O/ 18 O stable isotope labeling and peptide-centric identification and quantification by linear ion trap mass spectrometry. Using this approach we were able to identify more than fifty membrane proteins among a total of more than one hundred, from a preparation of 100 µg crude mitochondrial membranes. A part of this proteome was split into two and subjected to comparative analysis by 16 O/ 18 O stable isotope labeling. A very narrow distribution of ratios was obtained, showing no evident deviations from the 1:1 ratio in more than two hundred quantifications. Our data demonstrated that significant changes in protein expression levels higher than 1.5-fold or lower than 0.6-fold could be detected at the p < 0.05 confidence le vel. Our results suggest that this method could be suitable for the large-scale identification and relative quantification of mitochondrial membrane proteomes, as well as other protein membrane preparations. | We describe an algorithm for the automated statistical analysis of protein abundance ratios (ASAPRatio) of proteins contained in two samples. Proteins are labeled with distinct stable-isotope tags and fragmented, and the tagged peptide fragments are separated by liquid chromatography (LC) and analyzed by electrospray ionization (ESI) tandem mass spectrometry (MS/MS). The algorithm utilizes the signals recorded for the different isotopic forms of peptides of identical sequence and numerical and statistical methods, such as Savitzky−Golay smoothing filters, statistics for weighted samples, and Dixon's test for outliers, to evaluate protein abundance ratios and their associated errors. The algorithm also provides a statistical assessment to distinguish proteins of significant abundance changes from a population of proteins of unchanged abundance. To evaluate its performance, two sets of LC-ESI-MS/MS data were analyzed by the ASAPRatio algorithm without human intervention, and the data were related to the exp... | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 27,231 |
While photoaffinity ligands (PALs) have been widely used to probe the structures of many receptors and transporters, their effective use in the study of membrane-bound cytochrome P450s is less established. Here, lapachenole has been used as an effective photoaffinity ligand of human P450 3A4, and mass spectrometry data demonstrating the efficient and specific photoaffinity labeling of CYP3A4 by this naturally occurring benzochromene compound is presented. Without photolysis, lapachenole is a substrate of CYP3A4 and can be metabolized to hydroxylated products by this enzyme. A high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) procedure was developed to analyze small amounts of intact purified CYP3A4, and analysis of the labeled protein showed the presence of one molecule of lapachenole bound per monomer of protein. Photolabeled CYP3A4 peptide adducts were further characterized by mass spectrometric analysis after proteolytic digestion and isolation of fluorescent photolabeled peptides. Two peptide adducts accounting for >95% of the labeled peptides were isolated by HPLC, and both peptides, ECYSVFTNR (positions 97-105) and VLQNFSFKPCK (positions 459-469), were identified by nano-LC/ESI quadrupole time-of-flight (QTOF) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. The sites of modification were further localized to positions Cys-98 and Cys-468 for each peptide by nano-LC/ESI QTOF tandem mass spectrometry (MS/MS). The results provided the first direct evidence for interaction between the PAL and the putative B-B' loop region, which may serve as a substrate access channel or as a part of the CYP3A4 active site. In conclusion, benzochromene analogues are effective PALs, which may be used in the study of other cytochrome P450 structures. | The mechanism of inactivation of cytochrome P450 2B1 (CYP2B1) by 4-tert-butylphenylacetylene (BPA) has been characterized previously to be caused by the covalent binding of a reactive intermediate to the apoprotein rather than heme destruction (J Pharmacol Exp Ther 331:392–403, 2009). The identification of a BPA-glutathione conjugate and the increase in the mass of the BPA-adducted apoprotein have indicated that the mass of adduct is 174 Da, equivalent to the mass of BPA plus one oxygen atom. To identify the adducted residue, BPA-inactivated CYP2B1 was digested with trypsin, and the digest was then analyzed by using capillary liquid chromatography with a LTQ linear ion trap mass spectrometer as the detector. A mass shift of 174 Da was used for a SEQUEST database search. The tandem mass spectrometry fragmentation of the modified peptide and the identity of modified residue were determined. The results revealed a mass increase of 174 Da for the peptide sequence 296FFAGTSSTTLR308 in the I-helix of CYP2B1 and that the site of adduction formation is Thr302. Homology modeling and ligand docking studies showed that BPA binds in close proximity to both the heme iron and Thr302 with the distances being 2.96 and 3.42 Å, respectively. The identification of Thr302 in the CYP2B1 active site as the site of covalent modification leading to inactivation by BPA supports previous hypotheses that this conserved Thr residue may play a crucial role for various functions in P450s. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,232 |
A reversed phase gradient ultra performance liquid chromatography tandem mass spectrometry (UPLC/MS/MS) method has been developed for the analysis of smokeless powders. A total of 20 different components were separated by UPLC and detected by MS/MS in multiple reaction monitoring (MRM) mode. These compounds included diphenylamines, centralites, nitrotoluenes, nitroglycerin, and various phthalates. Simultaneous positive and negative electrospray ionization (ESI) was used along with negative atmospheric pressure chemical ionization (APCI) to detect all compounds in a single analysis. Analysis times were under 8 min with a gradient of 10-73% organic at a flow rate of 0.500 mL/min. With this method, ultraviolet and MRM limits of detection ranging from 0.08 to 2.6 ng and 0.4-64 ng injected were achieved. Commercially available smokeless powders were also extracted with methylene chloride and characterized using the developed UPLC/MS/MS method. The procedure permits the determination of compositional differences between different brands as well as lot-to-lot variations. | UHPLC-MS/MS is connected in various research facilities for the qualitative and quantitative investigation of a pharmaceutical substance, pharmaceutical items, and biological specimen. The commence review article is an endeavor to offer pervasive awareness around assorted aspects and details about the UHPLC-MS/MS and related techniques with the aim on practice to an estimation of medicinal active agents in the last 10 years. The article also focused on isolation, separation, and characterization of present impurity in drug and biological samples. Review article compiles a general overview of medicinally important drugs and their analysis with UHPLC-MS/MS. It gives fundamental thought regarding applications of UHPLC-MS/MS for the study on safety limit. The summary of developed UHPLC-MS/MS methods gives a contribution to the future trend and limitations in this area of research. | MLL1 regulates circadian promoters by depositing H3K4 trimethyl marks, whose levels are also modulated by the NAD+-dependent deacetylase SIRT1. SIRT1 is now shown to promote circadian deacetylation of MLL1, thus affecting MLL1's methyltransferase activity. | eng_Latn | 27,233 |
The rat ventral prostate accumulated lindane (γ-hexachlorocyclohexane) (0.59 ± 0.07 ppm) when this liposoluble toxicant was injected subcutaneously at a concentration of 1 mg of 100 g body weight for 12 days. Total lipids and phospholipids (especially phosphatidylcholine) amounts were augmented in treated rats. Lindane had no signficant influence upon cholesterol mass content in the ventral prostate. Using [1-14C]acetate as radioactive precursor, it was possible to conclude that the mass lipid variations caused by lindane treatment were due, at least in part, to a modification of the endogenous biosynthesis of these lipids. No changes were found in the acetate oxidation to CO2 when control rats and lindane-treated rats were compared. | Lindane (gamma-hexachlorocyclohexane) is a commonly used pesticide that bioaccumulates in mammalian adipose tissue. Lindane inhibits gap junctional intercellular communication and oscillatory contractions of pregnant rat myometrium in vitro. The present study investigated the role of oxidative stress in lindane's inhibition of myometrial function in mid-gestation pregnant rat uteri. Lucifer yellow dye was microinjected into cultured myocytes to assess gap junctional intercellular communication. Lindane exposure (100 microM) resulted in a time-dependent, biphasic inhibition of dye transfer. This pattern of inhibition was also seen upon cell exposure to the pro-oxidant, tert-butyl hydroperoxide (100 microM). Lindane's initial and secondary-onset dye transfer inhibitions were reversed by cotreatment and pretreatment with the antioxidants, alpha-tocopherol (25-100 microM), diphenyl-1,4-phenylene diamine (10-30 microM), and superoxide dismutase (100-400 U/ml). D-mannitol (100-300 mM) also reversed lindane's initial dye transfer inhibition. Nitro blue tetrazolium reduction to formazan (measured spectrophotometrically) was elevated upon exposure of cultured cells to lindane or tert-butyl hydroperoxide, indicating the presence of reducing agents. Lipid peroxidation, assessed as thiobarbituric acid-reactive substances, was also elevated in lindane-exposed cell cultures. alpha-Tocopherol reversed this elevation. Finally, uterine contractility was assessed by measuring isometric contractions of uterine strips hung in standard muscle baths. Pretreatment with alpha-tocopherol prevented lindane's abolishment of uterine contractions in vitro. These data support the hypothesis that lindane inhibits uterine contractility and myometrial gap junctions by establishing an oxidative stress environment. | Molecular characteristics of an atactic polystyrene (aPS) chain with different lengths in a theta solvent, cyclohexane at 307.65 K, were studied via molecular dynamics (MD) simulation. The interaction energy of the aPS dilute solution models and Flory–Huggins (FH) interaction parameter were calculated to investigate the effect of the chain molecular weight on its compatibility with the solvent molecules. The simulation results illustrated that increasing the chain length increased the interactions between the chain and the solvent molecules. The chain dimensions via calculating the radius of gyration (Rg) and end-to-end distance, , were measured. Mean square displacement (MSD) and diffusivity coefficient of the chains were calculated to determine their dynamic behavior. The results exhibited that two factors of the chain movability and size were important for the diffusion in oligomeric state. Additionally, viscosity of the resultant dilute solutions was calculated via nonequilibrium molecular dynamics simulation (NEMD). Moreover, the steric hindrance of the chains was determined by radial distribution function (RDF) analysis. The calculated characteristics of the chain and solution viscosity results showed a good agreement with experimental published works. Measurement of the potential field of cyclohexane–cyclohexane and aPS–cyclohexane pairs was also based on their potential field via quantum chemical calculations to determine the special orientation of the solvent molecules to each other and to the polymer segments, respectively. | eng_Latn | 27,234 |
This article reports the rapid detection of 10 underivatised steroids using surface-assisted laser desorption ionisation time-of-flight mass spectrometry (SALDI TOF-MS). Numerous carbon surfaces were investigated as possible substrates to promote underivatised steroid desorption and ionisation and compared to established matrix assisted laser desorption ionisation (MALDI) approaches. The inexpensive and readily accessible surface of activated carbon allowed detection of all 10 steroids of interest; estrone, β-estradiol, estriol, 17α-ethynylestradiol, progesterone, pregnenolone, 17α-hydroxy progesterone, corticosterone, cortisone and hydrocortisone with on plate limits of detection ranging from 1.57 to 18.1 ng. The activated carbon surface produced minimal background interference, simple mass spectral interpretation and significantly improved analyte distribution when compared to a more conventional MALDI approach. | A new Fe3O4/poly(є-caprolactone) (PCL) magnetite nanocomposite was fabricated and used as a sorbent for magnetically mediated PCL microspheres solid-phase extraction (MM-PCL-SPE) followed by gas chromatography–flame ionization detection (GC–FID) for monitoring of progesterone (PGN) hormone in biological and environmental matrices, namely blood serum, tap water, urine, and hospital wastewater. The nanomagnetite core of the sorbent was synthesized by a co-precipitation method. Magnetic nanoparticles (MNPs) were then microencapsulated with PCL microspheres using emulsion polymerization. The nanocomposite was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The magnetite sorbent can be effectively dispersed in aqueous solution and attracted to an external magnetic field. The MM-PCL-SPE process for PGN assay involved (a) dispersion of the sorbent in the donor phase aqueous solution with sonication, (b) exposure to a magnetic field to collect sorbent that had adsorbed the analyte, and (c) solvent desorption of extracted PGN for GC–FID analysis. The work demonstrates the usefulness of MM-PCL-SPE in the rapid and sensitive monitoring of trace amounts of PGN in real samples. The limit of detection (LOD) and limit of quantification (LOQ) were 1.00 and 3.30 ng/mL, respectively. The relative recoveries in real samples were adequate. Linearity was observed over a wide range of 2.2–10,000.0 ng/mL in aqueous media and urine and 0.01–70.0 μg/mL in blood serum. | MLL1 regulates circadian promoters by depositing H3K4 trimethyl marks, whose levels are also modulated by the NAD+-dependent deacetylase SIRT1. SIRT1 is now shown to promote circadian deacetylation of MLL1, thus affecting MLL1's methyltransferase activity. | eng_Latn | 27,235 |
The development and validation of chemometrics-assisted spectrophotometry have been successfully performed for determination of sodium benzoate and citric acid that have overlapping of ultra violet absorption spectra. The study aimed to develop, validate, and apply spectrophotometric method with chemometrics approach for determination of both compounds in beverage products simultaneously. The analytical method was performed by making a calibration model using 16 training sets and 10 test sets of mixed solution followed by absorbance measurenment at wavelength of 190 nm up to 400 nm. In addition, the absorbance data was processed by multivariate calibration models of principal component regression (PCR) and partial least square-1 (PLS-1) and validated internally and externally to obtain optimum model. Validation of analytical methods was done by evaluating some parameters such as linearity and ranges, accuracy, precision, detection limits and quantification limits. The results showed that the optimum wavelength was 235 nm to 250 nm for sodium benzoate and 220 nm to 240 nm for citric acid with the selected optimum principal components (PCs) value were 6 (PCR) and 4 (PLS-1) for sodium benzoate and PCs 2 (PCR and PLS-1) for citric acid. The parameters of the analytical method validation developed were suitable and the analytical methods could be applied for the determination of the sodium benzoate and citric acid contents simultaneously in the beverage products. | Citric acid is a food additive that is widely used in the food and drink industry. We investigated the effects of citric acid injection on mouse kidney. Forty healthy mice were divided into four groups of 10 including one control group and three citric acid-treated groups. Low dose, middle dose and high dose groups were given doses of 120, 240 and 480 mg/kg of citric acid, respectively. On day 7, kidney tissues were collected for histological, biochemical and molecular biological examination. We observed shrinkage of glomeruli, widened urinary spaces and capillary congestion, narrowing of the tubule lumen, edema and cytoplasmic vacuolated tubule cells, and appearance of pyknotic nuclei. The relation between histopathological changes and citric acid was dose dependent. Compared to the control, T-SOD and GSH-Px activities in the treated groups decreased with increasing doses of citric acid, NOS activity tended to increase, and H2O2 and MDA contents gradually decreased, but the differences between any treated group and the control were not statistically significant. The apoptosis assay showed a dose-dependent increase of caspase-3 activity after administering citrate that was statistically significant. DNA ladder formation occurred after treatment with any dose of citric acid. We concluded that administration of citric acid may cause renal toxicity in mice. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,236 |
Rhodanese a ubiquitous sulphur transferase enzyme catalyses the detoxification of cyanide to a less toxic thiocyanate. Rhodanese from the root of Pentadiplandra brazzeana was purified by ammonium sulphate precipitation and affinity chromatography. The enzyme had a specific activity of 4.82 RU/mg of protein. The Km values of the substrates (KCN and Na2S2O3) were 11.76 and 10 mM, respectively. The optimum pH and temperature of the enzyme activity were 8.0 and 60°C, respectively. The enzyme was not inhibited by the heavy metals (BaCl2, KCl, NiCl2, NaCl, MnCl2, and ZnCl2). This study affirmed the presence of rhodanese in the root of P. brazzeana, an indication that the plant may be of useful biotechnological application, especially in bioremediation of cyanide intoxified farm sites. ::: ::: ::: ::: Key words: Cyanide, rhodanese, detoxification, inhibition, Pentadiplandra brazzeana. | Summary Cyanide is a potent and rapidly‐acting asphyxiant which prevents tissue utilization of oxygen by inhibition of the cellular respiratory enzyme, cytochrome oxidase. Inhalation or ingestion of cyanide produces reactions within a few seconds and death within minutes. Cyanide toxicity of dietary origin has been implicated in acute animal deaths and as major etiologic factors in toxic ataxic neuropathy in man and as a cause of vision failure in humans suffering from tobacco amblyopia and leber's hereditary optic atrophy. Diagnosis of cyanide toxicity may be confirmed by a variety of laboratory procedures, but accurate assay is essential for proper conclusions from analysis of animal tissues several hours after death or from human samples in instances of chronic dietary exposure. Biological detoxification of cyanide is available through several routes, and the application of sodium nitrite with sodium thiosulfate or administration of methylene blue are effective treatment procedure. The environmental av... | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,237 |
Objective ::: Na+ can be stored in muscle and skin without commensurate water accumulation. The aim of this study was to assess Na+ and H2O in muscle and skin with MRI in acute heart failure patients before and after diuretic treatment and in a healthy cohort. ::: ::: ::: Methods ::: Nine patients (mean age 78 years; range 58–87) and nine age and gender-matched controls were studied. They underwent 23Na/1H-MRI at the calf with a custom-made knee coil. Patients were studied before and after diuretic therapy. 23Na-MRI gray-scale measurements of Na+-phantoms served to quantify Na+-concentrations. A fat-suppressed inversion recovery sequence was used to quantify H2O content. ::: ::: ::: Results ::: Plasma Na+-levels did not change during therapy. Mean Na+-concentrations in muscle and skin decreased after furosemide therapy (before therapy: 30.7±6.4 and 43.5±14.5 mmol/L; after therapy: 24.2±6.1 and 32.2±12.0 mmol/L; p˂0.05 and p˂0.01). Water content measurements did not differ significantly before and after furosemide therapy in muscle (p = 0.17) and only tended to be reduced in skin (p = 0.06). Na+-concentrations in calf muscle and skin of patients before and after diuretic therapy were significantly higher than in healthy subjects (18.3±2.5 and 21.1±2.3 mmol/L). ::: ::: ::: Conclusions ::: 23Na-MRI shows accumulation of Na+ in muscle and skin in patients with acute heart failure. Diuretic treatment can mobilize this Na+-deposition; however, contrary to expectations, water and Na+-mobilization are poorly correlated. | Sodium intake is undoubtedly indispensable for normal body functions but can be detrimental when taken in excess of dietary requirements. The consequences of excessive salt intake are becoming increasingly clear as high salt consumption persists across the globe. Salt has long been suspected to promote the development of hypertension and cardiovascular diseases and is now also recognized as a potential modulator of inflammatory and autoimmune diseases through its direct and indirect effects on immune cells. The finding that, in addition to the kidneys, other organs such as the skin regulate sodium levels in the body prompted new hypotheses, including the concept that skin-resident macrophages might participate in tissue sodium regulation through their interactions with lymphatic vessels. Moreover, immune cells such as macrophages and different T cell subsets are found in sodium-rich interstitial microenvironments, where sodium levels modulate their function. Alterations to the intestinal bacterial community induced by excess dietary salt represent another relevant axis whereby salt indirectly modulates immune cell function. Depending on the inflammatory context, sodium might either contribute to protective immunity (for example, by enhancing host responses against cutaneous pathogens) or it might contribute to immune dysregulation and promote the development of cardiovascular and autoimmune diseases. | Fluorous tagging strategy is applied to solution-phase parallel synthesis of a library containing hydantoin and thiohydantoin analogs. Two perfluoroalkyl (Rf)-tagged α-amino esters each react with six aromatic aldehydes under reductive amination conditions. Twelve amino esters then each react with 10 isocyanates and isothiocyanates in parallel. The resulting 120 ureas and thioureas undergo spontaneous cyclization to form the corresponding hydantoins and thiohydantoins. The intermediate and final product purifications are performed with solid-phase extraction (SPE) over FluoroFlashTM cartridges, no chromatography is required. Using standard instruments and straightforward SPE technique, one chemist accomplished the 120-member library synthesis in less than five working days, including starting material synthesis and product analysis. | eng_Latn | 27,238 |
An analytical method for kanamycin A, amikacin and tobramycin of aminoglycoside (AG) antibiotics in milk samples was proposed using capillary zone electrophoresis (CZE) with post-column derivatization and laser-induced fluorescence detection. A simple and convenient homemade coaxial-gap reactor was adopted in the post-column derivatization of the AGs with 1.0 mmol/L naphthalene-2,3-dicarboxaldehyde and 8.0 mmol/L 2-mercaptoethanol in 35 mmol/L sodium tetraborate buffer (pH 10.0) of 30% (v/v) methanol. 50 mmol/L sodium acetate (pH 5.0) containing 0.5 mmol/L cetyltrimethyl ammonium bromide was used as the separation buffer. The linear calibration concentrations and detection limits were from 2.1 x 10(-5) to 5.0 x 10(-2)g/L and in the range of 7 x 10(-6) to 2 x 10(-5)g/L, respectively. The recoveries of the AGs in milk samples were from 81.6 to 93.1% (n=3). | A simple, reliable, highly sensitive and selective spectrofluorimetric method has been developed for determination of certain aminoglycosides namely amikacin sulfate, tobramycin, neomycin sulfate, gentamicin sulfate, kanamycin sulfate and streptomycin sulfate. The method is based on the formation of a charge transfer complexes between these drugs and safranin in buffer solution of pH 8. The formed complexes were quantitatively extracted with chloroform under the optimized experimental conditions. These complexes showed an excitation maxima at 519-524 nm and emission maxima at 545-570 nm. The calibration plots were constructed over the range of 4-60 pg mL(-1) for amikacin, 4-50 pg mL(-1) for gentamicin, neomycin and kanamycin, 4-40 pg mL(-1) for streptomycin and 5-50 pg mL(-1) for tobramycin. The proposed method was successfully applied to the analysis of the cited drugs in dosage forms. The proposed method was validated according to ICH and USP guidelines with respect to specificity, linearity, accuracy, precision and robustness. The high sensitivity of the proposed method allowed determination of amikacin and gentamicin in spiked and real human plasma. | A simple, reliable, highly sensitive and selective spectrofluorimetric method has been developed for determination of certain aminoglycosides namely amikacin sulfate, tobramycin, neomycin sulfate, gentamicin sulfate, kanamycin sulfate and streptomycin sulfate. The method is based on the formation of a charge transfer complexes between these drugs and safranin in buffer solution of pH 8. The formed complexes were quantitatively extracted with chloroform under the optimized experimental conditions. These complexes showed an excitation maxima at 519-524 nm and emission maxima at 545-570 nm. The calibration plots were constructed over the range of 4-60 pg mL(-1) for amikacin, 4-50 pg mL(-1) for gentamicin, neomycin and kanamycin, 4-40 pg mL(-1) for streptomycin and 5-50 pg mL(-1) for tobramycin. The proposed method was successfully applied to the analysis of the cited drugs in dosage forms. The proposed method was validated according to ICH and USP guidelines with respect to specificity, linearity, accuracy, precision and robustness. The high sensitivity of the proposed method allowed determination of amikacin and gentamicin in spiked and real human plasma. | eng_Latn | 27,239 |
Increasing evidence indicates that a disturbance of normal iron homeostasis and an amyloid- (A)-iron interaction may contribute to the pathology of Alzheimer’s disease (AD), whereas iron chelation could be an effective therapeutic intervention. In the present study, transgenic mice expressing amyloid precursor protein (APP) and presenilin 1 and watered with high-dose iron served as a model of AD. We evaluated the effects of intranasal administration of the high-affinity iron chelator deferoxamine (DFO) on A neuropathology and spatial learning and memory deficits created in this AD model. The effects of Fe, DFO, and combined treatments were also evaluated in vitro using SHSY-5Y cells overexpressing the human APP Swedish mutation. In vivo, no significant differences in the brain concentrations of iron, copper, or zinc were found among the treatment groups. We found that high-dose iron (deionized water containing 10 mg/mL FeCl3) administered to transgenic mice increased protein expression and phosphorylation of APP695, enhanced amyloidogenic APP cleavage and A deposition, and impaired spatial learning and memory. Chelation of iron via intranasal administration of DFO (200 mg/kg once every other day for 90 days) inhibited iron-induced amyloidogenic APP processing and reversed behavioral alterations. DFO treatment reduced the expression and phosphorylation of APP protein by shifting the processing of APP to the nonamyloidogenic pathway, and the reduction was accompanied by attenuating the A burden, and then significantly promoted memory retention in APP/PS1 mice. The effects of DFO on iron-induced amyloidogenic APP cleavage were further confirmed in vitro. Collectively, the present data suggest that intranasal DFO treatment may be useful in AD, and amelioration of iron homeostasis is a potential strategy for prevention and treatment of this disease. | Background: There is evidence that iron may play a role in the pathology of Alzheimer's disease (AD). There may be genetic factors that contribute to iron deposition resulting in tissue damage thus exacerbating AD. ::: ::: Methods: We have genotyped 269 healthy elderly controls, 191 cases with definite or probable AD, and 69 with mild cognitive impairment (MCI) from the OPTIMA cohort. ::: ::: Results: We have examined the interaction between the C2 variant of the transferrin (TF) gene and the C282Y allele of the haemochromatosis (HFE) gene as risk factors for developing AD. Our results showed that each of the two variants was associated with an increased risk of AD only in the presence of the other. Neither allele alone had any effect. Carriers of both variants were at 5 times greater risk of AD compared with all others. The interaction was significant by logistic regression (p = 0.014) and by synergy factor analysis (p = 0.015, synergy factor = 5.1). Further, carriers of these two alleles plus apolipoprotein E e4 (APOE4) were at still higher risk of AD: of the 14 tri-carriers of the three variants, identified in this study, 12 had AD and two MCI. ::: ::: Conclusion: We suggest that the combination of TF C2 and HFE C282Y may lead to an excess of redox-active iron and the induction of oxidative stress in neurones, which is exacerbated in carriers of APOE4. Since 4% of Northern Europeans carry the two iron-related variants and since iron overload is a treatable condition, these results merit replication. | This study was conducted to quantify the adsorption of desferrioxamine-B (DFO-B), a commercial trihydroxamate siderophore, onto an Oxisol and particularly examine the DFO-B-promoted soil dissolution in the presence of two small organic acids (citric and oxalic acids). Adsorption of DFO-B to Oxisol was rapid, and the adsorption isotherms yielded maximum surface concentrations of 9.59 μmol g−1 at pH 5.0, much lower than the soil cation exchange capacity. After reaching the maximum concentration within several minutes, the DFO-B adsorption to the soil subsequently decreased and attained a steady state, followed by a slight increase at the end of the reaction. Release of Fe, Mn, and Al from the soil was greatly enhanced in the presence of DFO-B. No competitive or synergic effect between the DFO-B and citric or oxalic acids was found on dissolution of Al- or Fe-containing minerals. However, a synergic effect between DFO-B and citric acid on dissolution of Mn-containing minerals was found, and a slight competitive effect of oxalic acid on release of Mn promoted by DFO-B was observed. These results can enhance our understanding on the role of siderophores in soils dissolution and weathering as well as the release of nutrient elements in the presence of low-molecular-weight organic acids. | eng_Latn | 27,240 |
An axial gradient, infrared optical material, ZnSxSe1−x, has been developed by codepositing ZnS and ZnSe in a controlled manner via a chemical vapor deposition process. This material has been characterized by measuring the compositional and refractive-index profiles, visible, and IR transmission, microstructure, and hardness. Axial index gradients produced thus far range from 0.024 to 0.066 mm−1 over a thickness of ~4 mm. An analytical model of the deposition process has been developed and successfully used to derive a deposition algorithm to produce specific index gradients. | The materials community realized that zinc sulfide (ZnS) was an important optical material for infrared windows over ::: forty years ago. Chemical vapor deposition (CVD) quickly became the method of choice for producing large ZnS ::: windows and domes. In addition to the development initiated in the United States, several international efforts for ::: understanding the processing and properties of CVD ZnS are notable. This paper summarizes the published history of ::: non-U.S. CVD ZnS development including the significant efforts in the United Kingdom, the former Soviet Union, ::: Israel, China, and Japan. | The oxidative polymorphism of debrisoquine (DBQ) has been determined in 89 patients with colo-rectal cancer and in 556 normal control subjects. Four patients and 34 controls, with a metabolic ratio >12.6, were classified as poor metabolisers of DBQ (n.s.). | eng_Latn | 27,241 |
The potential for acute toxicity from Dynabeads1 M-450 Sheep Anti-Mouse IgG ST (SAM-Beads) administered once intravenously to male and female rats was assessed. SAM-Beads in saline containing 0.5% plasma protein fraction (PPF) was intravenously administered at dosages of 9.6 times 104 or 8.3 times 108 beads/kg at a rate of ≥2.5 ml/min/kg. Rats administered 9.6 times 104 beads/kg were killed 14 days posttreatment. Rats administered 8.3 times 108 beads/kg were killed either 14 or 42 days posttreatment. Saline containing 0.5% PPF served as the control article. Treatment groups were statistically compared with respect to clinical chemistry, hematology parameters, and body weight data. No significant group differences were detected (α = 0.01) with respect to any statistically analyzed data. No SAM-Beads were detected in urine samples collected overnight posttreatment. No test beads were found in any of the tissues from animals administered 9.6 times 104 beads/kg. The SAM-Beads were evident in the lung, liver, ... | Microspheres of five sizes and of three different materials were used to estimate the safety factor in. pulmonary perfi&on scintigraphy as a function of particle size. Particle suspensions of varying concentrations were injected into the tail vein of unanesthetized albino CD rats and mice. The LD50 (24 hr) for rats was found to range from 154,000 to 705 particles per gram body weight as particle diameter ranged conversely from 13.5 to 90.7 @. The slope of the survival curves for rats showed the minimum lethal dose (MLD) to be about 25% lower than the LD50. When extrapolated to the clinical situation, these data yield safety factors of 1,663 to 16,630 for in jected doses of 1 million to 100,000 microspheres 28.0 @ in diameter. The safety factor drops dramatically to 36 with an injected dose of 1 million particles 90.7 ,-@ in diameter. J NuciMed19: 1209—1213, 1978 | Polyamines (PAs) are natural compounds involved in many growth and developmental processes in plants, and, specifically in fruits, play a vital role regulating its development, ripening and senescence processes. Putrescine (PUT), spermine (SPE), and spermidine (SPD) are prominent PAs applied exogenously to extend shelf life of fruits. They also originate endogenously during developmental phases of horticultural crops and simultaneously affect the quality attributes and shelf life. Their anti-ethylene nature is being exploited to enhance the shelf life when exogenously applied on fruits. In growth and development of fruits, PA levels generally fall, which marks the beginning of senescence at postharvest phase. PUT, SPE and SPD treatments are being applied during postharvest phase to prolong the shelf life. They enhance the shelf life of fruits by reducing respiration rate, ethylene release and enhance firmness and quality attributes in fruits. PAs have a mitigating impact on biotic and abiotic stresses including chilling injury (CI) in tropical and sub-tropical fruits. PAs are environment friendly in nature and are biodegradable without showing any negative effect on environment. Biotechnological interventions by using chimeric gene constructs of PA encoding genes has boosted the research to develop transgenic fruits and vegetables which would possess inherent or in situ mechanism of enhanced biosynthesis of PAs at different stages of development and thereby will enhance the shelf life and quality in fruits. Internal and external quality attributes of fruits are improved by modulation of antioxidant system and by strengthening biophysical morphology of fruits by electrostatic interaction between PAs and phospholipids in the cell wall. | eng_Latn | 27,242 |
In Part I of this work, we developed a method for the detection of drugs of abuse in biological samples based on fast gradient elution liquid-chromatography coupled with diode array spectroscopic detection (LC-DAD). In this part of the work, we apply the chemometric method of target factor analysis (TFA) to the chromatograms. This algorithm identifies the target compounds present in chromatograms based on a spectral library, resolves nearly co-eluting components, and differentiates between drugs with similar spectra. The ability to resolve highly overlapped peaks using the spectral data afforded by the DAD is what distinguishes the present method from conventional library searching methods. Our library has a mean list length (MLL) of 1.255 and a discriminating power of 0.997 when both retention index and spectral factors are considered. The algorithm compares a library of 47 different compounds of toxicological relevance to unknown samples and identifies which compounds are present based on spectral and retention index matching. The application of a corrected retention index for identification rather than raw retention times compensates for long-term and column-to-column retention time shifts and allows for the use of a single library of spectral and retention data. Training data sets were used to establish the search and identification parameters of the method. A validation data set of 70 chromatograms was used to calculate the sensitivity (correct identification of positives) and specificity (correct identification of negatives) of the method, which were found to be 92% and 94%, respectively. | This is a review of the literature regarding high-performance liquid chromatography-diode array detection (HPLC-DAD) procedures for the detection and determination of several categories of central nervous system–acting drugs in blood, plasma, or serum samples. Psychiatric and neurological drugs, such as antidepressants, benzodiazepines, antipsychotics, antiepileptics, and antiparkinsonians, have been included because of their relevance to therapeutic drug monitoring and systematic toxicological analysis. Articles published between 2000 and January 2012 have been taken into consideration. This review has focused on methodological approaches, sample pretreatment techniques, and other practical aspects. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,243 |
Nitroimidazoles are a class of veterinary drugs used for the treatment and prevention of certain bacterial and protozoal diseases in poultry, swine dysentery and genital trichomoniasis in cattle. Since the safety assessment of nitroimidazoles showed them to be genotoxic, carcinogenic and mutagenic, a number of nitroimidazoles have been banned for therapeutic purposes in different countries. Moreover, nitroimidazoles have also been extensively used as growth promoters in food-producing animals. Due to their efficacious improvement in meat production and feed conversion, deliberate use still exists. Therefore, the illegal use of nitroimidazoles in animal husbandry must be monitored. A sensitive method based on LC-MS/MS for the simultaneous determination and confirmation of five banned nitroimidazole drugs including metronidazole, ronidazole, dimetridazole, metronidazole-OH (metabolite of metronidazole), and 2-hydroxymethyl-1-methyl-5-nitroimidazole (metabolite of ronidazole and dimetridazole) in bovine muscle, using ronidazole-d3 as an internal standard, was developed and validated. After extraction with ethyl acetate and evaporation, the nitroimidazoles were reconstituted in petroleum ether and purified, and LC-MS/MS analysis was performed. The method was validated according to Brazilian Regulation 24/2009 (equivalent to European Union Decision 2002/657/EC). Parameters such as decision limit (CCα), detection capability (CCβ), precision, accuracy, uncertaincy and ruggedness were determined. Average accuracy of the five nitroimidazoles from bovine muscle fortified at 5 levels (0.5, 1.0, 1.5, 2.0 and 2.5 μg kg(-1)) ranged from 96% to 103%. The calculated CCα ranged from 0.0 to 0.17 μg kg(-1); CCβ ranged from 0.08 to 0.41 μg kg(-1). A complete statistical analysis was performed and the results indicate that the method is robust when subjected to day-to-day analytical variations. | In this work, MIL-101(Cr)@GO (Graphite Oxide) was synthesized using a hydrothermal synthesis method and was applied as a dispersive micro-solid-phase extraction (D-μ-SPE) sorbent for the efficient concentration of four residual drugs (metronidazole, MNZ; tinidazole, TNZ; chloramphenicol, CAP; sulfamethoxazole, SMX). Meanwhile, the extraction process was optimized by combining it with microwave-assisted extraction. Factors affecting the D-μ-SPE efficiency, such as selection of sorbent materials, pH of the sample solution, salting-out effect, amount of used material, extraction time, desorption solvent and desorption time, were studied. Under the optimal extraction conditions, the linearity ranged from 10 to 1000ngkg-1 and 1-100ngkg-1 (r2≥0.9928) for the target analytes. The limits of detection were between 0.08 and 1.02ngkg-1, and the limits of quantitation were between 0.26 and 3.40ngkg-1. Additionally, the developed method also exhibited good precision (RSD≤2.5%), repeatability (RSD≤4.3%), high recoveries (88.9%-102.3%) and low matrix effects (78.2%-95.1%). The proposed method proved to be an efficient and reliable approach for the determination of the analytes. Finally, we successfully detected the four drugs in chicken breast. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,244 |
Using the difference in stable carbon isotope ratio between a honey and its protein fraction permits objective evaluation of possible adulteration of honey with small amounts (7-20%) as well as larger amounts of corn or cane sugar. The present uncertainty in interpretation of results from pure honey with delta 13C values outside the generally accepted limits for pure honey of -27.5% to -23.5% is eliminated; likewise TLC testing to resolve questionable samples with delta 13C values between -23.5 and -21.5% is not needed. Fifty certified samples of pure honey were used to establish criteria for purity, and 38 other samples with delta 13C values in the "questionable" or "adulterated" range for the AOAC official method were tested. A difference of 1.0% or more between honey and protein fractions is proposed to indicate adulteration. | This review covers mainly publications that appeared in Analytical s (Royal Society of Chemistry) from January 1990 to February 2001. The number of publications on this topic continues to grow, and during the past three years (1998-2000) about 150 reviews and/or overviews have been published in the area of food. Numerous techniques and food matrices or chemical components are presented and discussed in these reviews. The present review is intentionally limited to eight techniques or classes of techniques and intends to be a "technique by technique" presentation of "what was used" or "what is used" to characterize food products and to detect their possible adulteration. The present review focuses on the following techniques: microscopic analysis; HPLC; GC, GC-(MS, FTIR); UV-visible spectrophotometry; AAS/AES, ICP-(AES, MS); IRMS, GC-IRMS, GC-C-IRMS; DSC; IR, mid-IR, and NMR (202 references). Emphasis is placed as much as possible on chemometrical treatment of analytical data, which are commonly used to achieve the final objective, either food characterization or adulteration detection. Finally, a brief description is given of the new generation of analytical systems that combine powerful analytical techniques and powerful computer software for a best extraction of the information from analytical data. | This work presents a study of the chemical structure, thermal degradation and electric conductivity of spherical particles synthesized as a result of intense crosslinking of pyrroles in plasma glow discharges. A new method to calculate crosslinking, hydrogenation and fragmentation in polymers was developed in this task based on XPS calculations. The results indicated that the percentages of hydrogenated states in polypyrrole particles varied in the 37.1–46.6 % and 55.5–58.5 % intervals for C and N, respectively. The participation of crosslinked states increased from 48.5 to 59.8 % with the energy of synthesis considering C atoms and decreased from 24 to 6 % for N atoms. The particles have two thermal degradations, the first between 115 and 400 °C and the second with mean temperature degradation of 535 °C. The electric conductivity of the particles was in the range of 10−5–10−10 S/m with activation energy between 1.96 and 2.34 eV. This behavior can be associated with the crosslinking percentages in the particles. | eng_Latn | 27,245 |
In this work a method is proposed and demonstrated for the analysis of the macrocyclic lactones abamectin, doramectin, eprinomectin, ivermectin and moxidectin in bovine milk by liquid chromatography coupled to mass spectrometry (LC-MS/MS) and liquid chromatography with fluorescence detection (LC-FL). The method is based on liquid-liquid extraction followed by a low temperature purification (LLE-LTP) step. Moreover, the proposed method was validated according to the Commission Decision 2002/657/EC, using LC-MS/MS and LC-FL for confirmatory and quantitative analysis, respectively. For LC-MS/MS the recovery rates observed ranged from 101.2 to 141.6% with coefficient of variation from 2.6 to 19.8%. For LC-FL the recovery rates observed ranged from 100.2 to 105% and coefficient of variations from 2.9 to 8.8%. Matrix effects were negligible due to the low temperature purification step. The quantification limits were far below the maximum limits established by regulations of all countries consulted. The proposed method proved to be simple, easy, and adequate for high-throughput analysis of a large number of samples per day at low cost. | Veterinary drug residues in bulk tank milk are important to all sectors of the dairy chain because they are one of the major factors which determine the safety of the final product. This study attempted to identify milk quality parameters that are associated with the occurrence of veterinary drug residues using multivariate principal component analysis (PCA). A total of 132 raw milk samples were collected from 45 dairy farms in the state of Minas Gerais - Brazil and analyzed for 42 analytes, including pyrethroids, macrocyclic lactones and antibacterials, using liquid chromatography coupled with mass spectrometry in tandem mode and gas chromatography with electron capture detection. Out of the 132 milk samples, 40 samples tested positive for at least one analyte (above the detection limit). The milk parameters associated with the antimicrobial residues by confirmatory tests were lactose and nonfat concentrations, as revealed by PCA. This analysis showed that fat and total solid concentrations, as well as the somatic cell and total bacteria counts were associated with macrocyclic lactone residues in bulk tank milk. A PCA assessing pyrethroid residues in bulk tank milk revealed that the lactose and nonfat solid concentrations and titratable acidity were inversely associated with these residues. Thus, the data analysis indicated that the veterinary drug residues were associated with certain milk quality parameters that can be used to target farms at higher risk of veterinary drug residue contamination for testing programs in combination with incentives, education and training programs to improve mammary health, milk hygiene and safety. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,246 |
The headspace solid-phase micro-extraction(SPME) coupled with gas chromatography/mass spectrometry was used to determine an odorous compound-dimethyl trisulfide in water.The optimal operation conditions of SPME were obtained as follows: using CAR/PDMS(85 μm) coated fiber,25% NaCl(W/V) addition and extracting at 65 ℃ for 30 min.The detection limit of this method is 5 ng/L,and the relative standard deviation(RSD) and the recovery rate of standard addition are 2.2% to 7.1% and 71.5% to 87.3% respectively.By using this method,dimethyl trisulfide was detected in different source waters with concentrations between 9 and 40 ng/L,which merits attention. | Geosmin and 2-MIB are responsible for the majority of earthy and musty events related to the drinking water. These two odorants have extremely low odor threshold concentrations at ng L(-1) level in the water, so a simple and sensitive method for the analysis of such trace levels was developed by headspace solid-phase microextraction coupled to gas chromatography/mass spectrometry. In this study, the orthogonal experiment design L32 (4(9)) was applied to arrange and optimize experimental conditions. The optimum was the following: temperatures of extraction and desorption, 65°C and 260°C, respectively; times of extraction and desorption, 30 min and 5 min, respectively; ionic strength, 25% (w/v); rotate-speed, 600 rpm; solution pH, 5.0. Under the optimized conditions, limits of detection (S/N = 3) were 0.04 and 0.13 ng L(-1) for geosmin and 2-MIB, respectively. Calculated calibration curves gave high levels of linearity with a correlation coefficient value of 0.9999 for them. Finally, the proposed method was applied to water samples, which were previously analyzed and confirmed to be free of target analytes. Besides, the proposal method was applied to test environmental water samples. The RSDs were 2.75%~3.80% and 4.35%~7.6% for geosmin and 2-MIB, respectively, and the recoveries were 91%~107% and 91%~104% for geosmin and 2-MIB, respectively. | In this work, MIL-101(Cr)@GO (Graphite Oxide) was synthesized using a hydrothermal synthesis method and was applied as a dispersive micro-solid-phase extraction (D-μ-SPE) sorbent for the efficient concentration of four residual drugs (metronidazole, MNZ; tinidazole, TNZ; chloramphenicol, CAP; sulfamethoxazole, SMX). Meanwhile, the extraction process was optimized by combining it with microwave-assisted extraction. Factors affecting the D-μ-SPE efficiency, such as selection of sorbent materials, pH of the sample solution, salting-out effect, amount of used material, extraction time, desorption solvent and desorption time, were studied. Under the optimal extraction conditions, the linearity ranged from 10 to 1000ngkg-1 and 1-100ngkg-1 (r2≥0.9928) for the target analytes. The limits of detection were between 0.08 and 1.02ngkg-1, and the limits of quantitation were between 0.26 and 3.40ngkg-1. Additionally, the developed method also exhibited good precision (RSD≤2.5%), repeatability (RSD≤4.3%), high recoveries (88.9%-102.3%) and low matrix effects (78.2%-95.1%). The proposed method proved to be an efficient and reliable approach for the determination of the analytes. Finally, we successfully detected the four drugs in chicken breast. | eng_Latn | 27,247 |
Four-month old adult siblings of zebrafish were exposed to four concentrations of diazinon for up to 168 h. DNA, RNA, protein and total free amino acid content were monitored in the liver. The DNA, RNA and protein contents were significantly reduced, whereas the amino acid content was significantly enhanced. All these changes showed dose- as well as time-dependent response. | Dimethoate and Diazinon are two of widely used organophosphorus insecticides in agriculture. The irrational use of Dimethoata and Diazinon in Yemen play a crucial role in the occurrence of many diseases affecting plants, animals and man. The present work was conducted to investigate the alterations in biochemical and hematological factors in male rabbits after orally administration a single dose of 1/4 LD50 of Dimethoate and Diazinon for 20 days. 30 Male Rabbits weighting 1500-1700g., were divided into 3 groups with 10 animals in each, first group served as control animals, they received 5 ml. of corn oil, while animals in second group received 1/4 LD50 of Dimethoate, animals in third group received 1/4 of LD50 of Diazinon .The concept of this study was to evaluate the hepatotoxic, and nephrotoxic effects of Dimethoate and Diazinon, therefore, the followings Biochemical parameters in serum were studied: aminotransferases (ALT and AST), alkaline phosphatase (ALP), total proteins, albumin, uric Acid, creatinin, and blood glucose. The followings hematological parameters were studied in blood: red blood cells (RBC), hemoglobin (Hb), and erythrocytes sedimentation rate (ESR).The Biochemical analysis showed that the levels of the ALT and AST as well as ALP, uric acid, creatinin, and blood glucose in the serum of treated rabbits significantly (P<0.01) increased compared to control animals, whereas either, total protein, and albumin, significantly decreased (P<0.01). Hematological factors were reduced in the treated groups. تاديبملارثكا نم نونيزايدلاو تاوثميدلا نايرشحلا ناديبملا ربتعي تاذ ةيرشحلا وضعوفسفلا بيكرتلا ةعارزلا يف امادختسا ي | In this research, the feasibility of using visible/near-infrared (Vis/NIR) spectroscopy combined with chemometrics was assessed for measurement of pesticide residues in agricultural products (a case study on Diazinon in greenhouse cucumber). Partial least squares (PLS) regression models were developed based on chemical reference measurements and the spectral information of the samples in 450-1000nm after performing different pre-processing methods. Results indicated that Vis/NIR spectroscopy combined with chemometrics have satisfactorily the potential for fast and non-destructive measurement of Diazinon residue in cucumber samples. Best prediction results were achieved with PLS model developed based on the combination of pre-processing methods of multiplicative scatter correction (MSC) and first derivative (D1) (rcv=0.91, SECV=3.22). | eng_Latn | 27,248 |
A novel immunochemical approach has been developed to monitor human exposures to ethylene oxide (EO). The method exploits the interaction of EO with the amino function of the N-terminal valine residue of the alpha-chain of human haemoglobin (Hb). Antibodies were raised against the adducted valine in the form of the N-terminal tryptic heptapeptide and have been used to develop a sensitive radioimmunoassay (RIA) for the adducted heptapeptide. This method has been fully validated against a gas chromatography-mass spectrometry (GC-MS) method and has been applied to the monitoring of EO exposure in a group of sterilization workers. | Immunoassays are analytical methods that detect interactions between antibodies and antigens. Immunoassays were used originally to detect large biological molecules. The new generation of these antibody-based assays can detect small synthetic compounds. As a result, immunoassays are being developed specifically for biomarkers of exposure and effect to environmentally prevalent chemicals. Immunochemical detection of parent compounds in blood and tissues, metabolites in excreta, and adducts with DNA and protein have been successfully performed by several investigators. Although there is great potential for use of immunoassays in biological monitoring studies, the limitations of these analyses must be fully understood to prevent improper evaluation of the acquired data. This review will cover some of the background material necessary to understand how an antibody-based assay is developed. The differences between polyclonal and monoclonal antibody-based assays and the importance of antibody class, affinity, specificity, and cross-reactivity must be considered in both study design and data analysis. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,249 |
In this study, we attempted to elucidate the metabolic pathway and enzymes actually involved in oxalate formation from glycolate in rat and human liver. In rat liver, the formation of oxalate from glycolate appeared to take place predominantly via glyoxylate. The oxalate formation from glycolate observed with crude enzyme preparations was almost entirely accounted for by the sequential actions of glycolate oxidase and xanthine oxidase (XOD) or lactate dehydrogenase (LDH). Under the conditions used, no significant activity was attributable to glycolate dehydrogenase, an enzyme reported to catalyze the direct oxidation of glycolate to oxalate. Among the three enzymes known to catalyze the oxidation of glyoxylate to oxalate, glycolate oxidase and XOD showed much lower activities (a higher Km and lower Vmax) toward glyoxylate than those with the respective primary substrates. As to LDH, none of the LDH subunit-deficient patients examined showed profoundly lowered urinary oxalate excretion. Based on the results obtained, the presumed efficacies in vivo of individual enzymes, as catalysts of glyoxylate oxidation, and the in vivo conditions assumed to allow their catalysis of oxalate production are discussed. | In this paper we studied the glyoxylate-dependent transamination of L-alanine and L-glutamate in human liver homogenates in order to develop a reliable method for the determination of true alanine:glyoxylate aminotransferase activity in liver homogenates from patients suspected to suffer from hyperoxaluria type I. Measurements were made according to two protocols described in literature in control human liver homogenates which were either untreated or treated with an antiserum raised against purified alanine:glyoxylate aminotransferase. The results obtained show that enzyme activity can best be determined at pH 8.0 as compared to pH 7.4 since the former leads to a higher sensitivity of the method. Alanine:glyoxylate aminotransferase activities measured at pH 8.0 are approximately 50% higher compared to the enzyme activities measured at pH 7.4. Accordingly, it is proposed to measure alanine:glyoxylate aminotransferase activity at pH 8.0 using the newly determined correction factor as described in this paper. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,250 |
PURPOSEWe conducted a prospective study on a large set of cancer patients in an attempt to evaluate the incidence of complete or partial dihydropyrimidine dehydrogenase (DPD) deficiency as found in peripheral mononuclear cells (PMNC).PATIENTS AND METHODSOne hundred eighty-five unselected consecutive cancer patients were included. The population consisted of 152 men (mean age, 62.1 years; range, 35 to 90) and 33 women (mean age, 59.2 years; range, 36 to 77). Sixty-eight were head and neck patients treated by a 5-day continuous infusion of fluorouracil (FU; starting dose, 1 g/m2/d, with dose adaptation based on pharmacokinetics) for which DPD activity was measured 2 to 3 days before FU administration (94 cycles analyzed). PMNC-DPD activity was measured by a radio-enzymatic assay using carbon-14-FU.RESULTSDPD activity in the entire population showed a unimodal distribution, which globally fits a gaussian distribution. Mean and median DPD activity values were 0.222 and 0.211 nmol/min/mg protein, respectively ... | Drug-metabolizing enzymes are responsible for the activation or detoxification of cytotoxic drugs. Allelic variants are present with a variable frequency in different populations around the world and have an important role in the therapeutic index of such drugs. It is known that polymorphisms in thiopurine methyltransferase and dihydropyrimidine dehydrogenase have been associated with altered drug metabolism and increased risk of severe toxicity from 6-mercaptopurine and 5-fluorouracil, respectively. Additionally, a variant number of dinucleotide-repeat sequences in the promotor for uridine 5'-diphosphate glucuronosyltransferase 1A1 influences the glucuronidation of SN-38, the active metabolite of irinotecan, which is associated with severe toxicity, including diarrhea and neutropenia. In the same way, polymorphisms in thymidylate synthase have been associated with pyrimidine-associated toxicity and also with response to chemotherapy. The examples shown in this review demonstrate the usefulness of pre-screening patients for well-characterized polymorphism to identify the best-tolerated and most-effective treatment. | The major purpose of this study was to investigate the level of development of creative potential among Hong Kong secondary school students, and to examine the relationship between school banding and students' creativity. Students' creative potential was measured by the Test of Creative Thinking Drawing Production (TCT-DP). A sample of2,411 participants aged between 12-16 randomly selected from 23 secondary schools took part in the study. Results from this investigation were briefly compared with data obtained from studies in other cultural settings. Hong Kong students aged 12 and 13, irrespective of the school banding, achieved rather lower scores on the TCT-DP as compared | eng_Latn | 27,251 |
Given the extensive efforts applied toward proteomics and research in biomarkers, methods for the simultaneous measurement of proteins, peptides, metabolic intermediates, hormones, etc. in a complex sample may be required in the foreseeable future. Assays based on mass spectrometric detection may be suitable for meeting the demands of such complex samples with sensitivity and specificity. An analytical method for the quantitation of C-reactive protein (CRP), a well-known marker of inflammation, is described. Exact quantities of two synthetic (13)C-labeled CRP tryptic peptides were added as internal standards directly to the sample prior to chemical treatment, trypsinization, and liquid chromatography/mass spectrometry quantitation. C-reactive protein levels based on isotopic response ratios were measured. Intact C-reactive protein was spiked into blank rat urine for chemical and enzymatic treatment, producing linear response ratios of labeled to unlabeled peptides. For rigorous quantitation, standard curves, and quality control samples were prepared in rat urine with highly purified labeled and unlabeled peptides over the 50 pg-5 ng/muL concentration range. Using the same chemical and enzymatic treatment used for digestion of intact CRP, data from these samples demonstrated excellent analytical performance. The method was successfully applied toward the quantitation of urinary C-reactive protein from a study of drug-induced nephrotoxicity. | In this review we will give an overview of the issues related to biomarker discovery studies with a focus on liquid chromatography-mass spectrometry (LC-MS) methods. Biomarker discovery is based on a close collaboration between clinicians, analytical scientists and chemometritians/statisticians. It is critical to define the final purpose of a biomarker or biomarker pattern at the onset of the study and to select case and control samples accordingly. This is followed by designing the experiment, starting with the sampling strategy, sample collection, storage and separation protocols, choice and validation of the quantitative profiling platform followed by data processing, statistical analysis and validation workflows. Biomarker candidates that result after statistical validation should be submitted for further validation and, ideally, be connected to the disease mechanism after their identification. Since most discovery studies work with a relatively small number of samples, it is necessary to assess the specificity and sensitivity of a given biomarker-based assay in a larger set of independent samples, preferably analyzed at another clinical center. Targeted analytical methods of higher throughput than the original discovery method are needed at this point and LC-tandem mass spectrometry is gaining acceptance in this field. Throughout this review, we will focus on possible sources of variance and how they can be assessed and reduced in order to avoid false positives and to reduce the number of false negatives in biomarker discovery research. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,252 |
The comparative carcinogenicities of N -hydroxy- N -acetyl-1-aminopyrene, N -acetyl-1-aminopyrene, and 1-, 2-, and 4-nitropyrene were determined following i.p. injection into weanling female CD rats (67 µmol/kg body weight in dimethyl sulfoxide; 3 times/week for 4 weeks). At sacrifice 61 weeks after the first injection the incidences of malignant mammary tumors were increased significantly to 45 and 24% in the 4-nitropyrene-and N -hydroxy- N -acetyl-2-aminofluorene-treated groups, respectively. Cellular altered foci in the liver were increased significantly in the N -acetyl-1-aminopyrene-, N -hydroxy- N -acetyl-1-aminopyrene-, and N -hydroxy- N -acetyl-2-aminofluorene-treated groups; the latter two compounds also led to significantly increased formation of hyperplastic nodules in this organ. Significant increases in leukemia induction were observed in animals treated with 2-nitropyrene or N -hydroxy- N -acetyl-2-aminofluorene. ::: ::: In an experiment designed to compare the influence of the route of administration on the carcinogenic potential of this agent, 1-nitropyrene was injected i.p. or s.c. into weanling female CD rats (100 µmol/kg body weight; once a week for 4 weeks). The animals were sacrificed at 87 to 90 weeks after the first treatment. The incidences of mammary gland tumors in animals receiving injections of 1-nitropyrene by either route (59%) were significantly higher than in solvent-injected controls (37%). The incidences of adenocarcinoma in the i.p. 1-nitropyrene group (28%) and fibroadenoma in the s.c. 1-nitropyrene group (52%) were significantly higher than in the control animals (7 and 27%, respectively). These data suggest that the demonstration of the weak carcinogenicity of 1-nitropyrene is probably more a function of the length of the observation period than of the routes of administration used here. ::: ::: A further exploration of the effect of the route of administration involved treatment of weanling female CD rats by direct injection of 1-, 2-, or 4-nitropyrene into the mammary fat pads. A total of 2.04 µmol of the nitrocompound in dimethyl sulfoxide was injected into the mammary glands under each of the 6 left nipples. The right mammary glands were treated with the solvent only. Injections of the thoracic nipple areas were carried out on day 1; inguinal areas were treated on day 2. The animals were sacrificed after 77 weeks. The number of mammary tumor-bearing animals (23 of 28), the number with fibroadenoma (15 of 28), and the number with adenocarcinoma (19 of 28) were significantly increased in the 4-nitropyrene-treated group as compared with animals treated with only dimethyl sulfoxide. Animals that had received 1- or 2-nitropyrene or the solvent dimethyl sulfoxide had mammary tumor incidences of only 21 to 22%. A majority of the animals that had been given 4-nitropyrene ( i.e. , 22 of 28) had tumors of the treated mammary glands as compared with only a few that developed tumors of the solvent-treated mammary glands ( i.e. , 5 of 28). These data confirm the carcinogenicity of 1-nitropyrene for rat mammary gland and demonstrate that 4-nitropyrene is the most potent of the three isomeric mononitropyrenes for this organ. The direct carcinogenicity of 4-nitropyrene for the mammary gland establishes that this target organ possesses the enzymes necessary for the metabolic activation of this carcinogen. | Nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) are well-known mutagens. Correlations between the orientation of the nitro group relative to the plane of the aromatic ring and mutagenic effects of nitro-PAHs have been proposed. Synthesis of specific isomers of nitro-PAHs and elucidation of their crystal structure is required to establish the validity of the structure-function relationships. Such studies are scarce. Fortunately, electronic structure calculations can be readily done. In this study we have used density functional theory calculations to predict structure of nitro-PAHs, including 1-, 2-nitronaphthalenes; 1-, 2-, 9-nitroanthracenes; 1-, 2-, 3-, 4-, 9-nitrophenanthrenes; 1-, 2-, 4-nitropyrenes; and 6-nitrochrysene. The relationships between the calculated structures and the mutagenicity reported in the chemical literature are discussed. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,253 |
The purpose of this study was to elucidate whether exogenous nitric oxide (NO) has a potential beneficial effect on lipase production capacity of some microorganisms. Sodium nitroprusside (SNP) was used as an exogenous NO donor in production medium. In comparison with the control (0 nM SNP), SNP concentrations from 10 to 100 nM induced lipase production in mesophilic bacterium Bacillus subtilis and cold-adapted yeast Yarrowia lipolytica. Especially, the maximum lipase activities for Y. lipolytica (81.2 U/L) and B. subtilis (74.5 U/L) were attained at 30 and 50 nM SNP concentrations, respectively. When compared to the control, the optimal SNP concentrations resulted in about 5.14 and 2.27-fold increases in lipase activities of B. subtilis and Y. lipolytica, respectively. Besides, it was found that the optimal SNP concentrations provided shorter incubation periods for lipase production. Conversely, no significant positive effect of exogenous NO on lipase production was determined for thermophilic bacterium Geobacillus stearothermophilus. This study showed for the first time that exogenous NO could be used as an inducer in the production of microbial lipases. | A hydroponics experiment was conducted to test the effects of sodium nitroprusside (SNP, a donor of NO) supplied with different concentrations on copper (Cu) toxicity in ryegrass seedlings (Lolium perenne L.). Excess Cu (200 µM) reduced chlorophyll content, resulting a decrease in photosynthesis. Cu stress induced the production of hydrogen peroxide (H2O2) and superoxide anion (O2• −), leading to malondialdehyde (MDA) accumulation. Furthermore, activities of antioxidant enzymes in Cu-treated seedlings such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were decreased. In addition, Cu stress inhibited the uptake of K, Mg, Fe, and Zn and increased Ca content in roots. Moreover, in leaves of Cu-stressed seedlings, K, Fe, and Zn contents were decreased and the contents of Ca and Mg were not affected significantly. In Cu-treated seedlings, Cu concentration in roots was higher than in leaves. Addition of 50, 100, 200 µM SNP in Cu-mediated solutions increased chlorophyll content and photosyn... | Recently, sodium nitroprusside (SNP), a potent nitric oxide (NO) donor and a clinically used antihypertensive, has been introduced as a penile self-injection medical therapy for erectile dysfunction. However, it is known that many antihypertensives impairs sexual competence; NO regulates sexual competence and NO is cytostatic and cytotoxic for human sperm. Thus, a possibility exists that SNP may impair male reproductive competence. Testing this aspect is the aim of this study. This was assessed in male rats (using three I.P. doses: 60, 30 or 20 g/kg) using noncompetitive copulation tests. The results show that the highest dose of SNP was toxic and caused rapid mortality of treated rats (within 30 min). The mid and low doses of SNP reversibly impaired several parameters of sexual competence in a dose-related fashion: sexual arousability, libido and sexual vigour. Some parameters of sexual behaviour remained unaltered: sexual motivation and intromission ratio, whilst one parameter was improved: sexual perfo... | eng_Latn | 27,254 |
A study of the electrochemical behaviour of ascorbic acid (AA) at the powder microelectrode revealed that exhaustive electrolysis of AA could be achieved within a narrow range of potential. As a result, the interference of AA in the amperometric detection of bioactive molecules in body fluid samples can be practically eliminated by employing the powder microelectrode technique. Elimination of the interference of AA can be further improved if the monitored biomolecules are strongly adsorbed on the surface of carbon powder. A good example of such a bioactive compound is uric acid (UA), which can be strongly adsorbed on the surface of acetylene black powder. In a mixture containing 0.8 μM–0.4 mM UA and a large excess of AA in 0.1 M phosphate buffer solution, the separation between the potentials of oxidation current peaks of UA and AA reaches 400 mV, and the height of the UA peak is linear with respect to the UA concentration. A very simple procedure for the detection of UA in human serum and urine samples has been worked out to illustrate the above-stated principle. Application of the same principle in the amperometric detection (and probably simultaneous determination) of other electroactive biomolecules also seems promising. | In this paper, carboxyl groups were introduced by liquid oxidation methods onto multi-walled carbon nanotubes (MWCNTs) to improve the MWCNTs’ electrocatalytic properties. A platinum wire microelectrode (ME) was corroded using aqua regia and subsequently embedded with MWCNTs to achieve more active sites, producing a so-called powder microelectrode (PME). Compared with conventional MEs, the PME has a larger specific surface area and more active sites. When PME was used to detect ascorbic acid (AA), the AA oxidation potential shifted negatively and current peak was visibly increased. The calibration curve obtained for AA was in a range of 5.00 × 10−6~9.50 × 10−4 mol·L−1: Ipa(μA) = 3.259 × 10−2 + 1.801 × 102 C (mol·L−1) under the optimum testing conditions. Moreover, the detection and quantitation limits were confirmed at 4.89 × 10−7 mol·L−1 and 1.63 × 10−7 mol·L−1, respectively. When the fabricated PME was practically applied to detect AA, it was shown a recovery rate of 94~107% with relative standard deviation (RSD) <5%. The proposed strategy thus offers a promising, rapid, selective and low-cost approach to effective analysis of AA. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,255 |
An ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry method for the direct analysis in oral fluid (OF) of several abused drugs and metabolites in a single chromatographic run was set up and validated. Amphetamine, methamphetamine, morphine, O-6-monoacetylmorphine, cocaine, codeine, methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine, methylenedioxyamphetamine, methadone, benzoylecgonine (BEG), Δ9-tetrahydrocannabinol (THC), ketamine, and cocaethylene were determined in a single chromatographic run with no sample pretreatment, after addition of the respective deuterated internal standards. The method was designed to perform a confirmation analysis on the residual OF samples after the preliminary on-site screening test, and it was applied on preservative buffers from different devices (Mavand Rapidstat, Concateno DDS, and Greiner Bio-One) or on neat OF samples. The method was suitable to be applied to the small amounts of sample available for the confirmatory analysis after the preliminary on-site screening or on undiluted OF samples. Limits of detection varied from 5 (morphine) to 0.2 ng/mL (methamphetamine, MDMA, BEG, and cocaethylene). The method was linear for all the substances involved, giving quadratic correlation coefficients of >0.99 in all the different preservative buffers checked. In addition, repeatability and accuracy were satisfactory for the majority of the substances, except for a few cases. The developed method was subsequently applied to 466 residual samples from on-site screening performed by police officers. Of these samples, 74 showed the presence of cocaine and metabolites; THC was detected in 49 samples. Two samples showed codeine and morphine while MDMA was detected in 11 samples and ketamine in four samples. | Oral fluid (OF) has become a valuable biologic specimen for toxicological analysis, especially in driving under the influence of drugs (DUID) investigations, because of easy and non-invasive collection procedures. In OF testing, being the sample volume is limited, multi-analyte procedures are particularly advantageous since they save time and resources. In this work, a procedure for the simultaneous analysis of 20 illicit drugs, belonging to the classes of cocaine, amphetamines, natural and synthetic opioids and hallucinogens, is presented. The sample preparation is based on microextraction by packed sorbent (MEPS), a novel technique which is based on the miniaturization of solid-phase extraction (SPE). The presented method, which includes all the most diffused illicit drugs and their metabolites, has been fully validated according to the Scientific Working Group for Forensic Toxicology (SWGTOX) guidelines. LLOQs ranged from 0.5 to 30 ng mL−1 (diacetylmorphine); the presented method allows the detection of all the selected drugs quite below the cutoff values recommended by Substance Abuse and Mental Health Services Administration (SAMHSA) for abuse identification. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,256 |
The instability of fresh erythrocytes sensitized for use in hemagglutination reactions prompted the use of formalinized erythrocytes. In the course of attempts to avoid nonspecific agglutination, the variables affecting sensitization of formalinized erythrocytes were explored extensively. Uptake of antigen by cells increased as the concentration of tannic acid and the time of exposure to tannic acid were increased. Increasing the concentration of antigen to which tanned cells were exposed as well as increasing the temperature and time of reaction resulted in greater uptake of antigen by the cells. The sensitization reaction was pH dependent, with pH optima varying for different antigens. Optimal sensitization of cells for use in the hemagglutination reaction did not correspond with maximal uptake of antigen by the cells. The optimal conditions for sensitizing cells for use in hemagglutination were determined for a number of protein antigens. Under these conditions cell preparations of great stability were produced which were comparable in sensitivity to those made with fresh erythrocytes. The mechanism by which antigens are tightly bound to the erythrocyte surface remains unknown. | Modifications of existing methods have allowed for the isolation and purification of various species of plasma glycosaminoglycans on the basis of their sulfate content and molecular size. All of the preparations precipitated human plasma low density lipoproteins (LDL); maximal precipitation occurred with amounts of glycans corresponding to 50 mug of hexuronate and 12 mg of LDL. The interaction of glycans with pyrene-labeled lipoproteins was also studied, measuring variations of the fluorescence emitted by the monomer (M) and excimer (E) species of the bound pyrene. The ratio IE/IM is proportional to c/eta, where c is the microscopic concentration of the pyrene confined to the hydrocarbon region of the lipoprotein and eta is the microviscosity of that region. To 0.12 mg of pyrene-labeled LDL, very low density lipoproteins (VLDL) or high density lipoproteins (HDL) were added increasing amounts of the various glycan preparations. The sulfate-rich species decreased the IE/IM ratio of LDL and HDL but not that of VLDL. This finding suggests that the glycan caused a change in lipoprotein conformation associated with either an increased volume or increased microscopic viscosity of the hydrocarbon region. The modification of LDL conformation could be prevented by proteolytic treatment of the sulfate-rich species or by addition to the system of suitable amounts of sulfate-poor species or of chrondroitin-4-sulfate, but could not be prevented by increased ionic concentration. These results suggest that the two main species of plasma glycans are important in maintaining adequate rheological properties of plasma lipoproteins. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,257 |
The peroxisomal enzyme dihydroxyacetone phosphate (DHAP) acyltransferase shows a differential response to acetaldehyde. Employing whole peroxisomes, the enzyme displays a 130-400% stimulation of activity when assayed in the presence of 10-250 mM acetaldehyde. Following taurocholate solubilization of the enzyme the response to 0.25 M acetaldehyde is one of almost total inhibition. This inhibition of the taurocholate-solubilized enzyme is not observed at acetaldehyde concentrations below 200 mM. The stimulation of DHAP acyltransferase by acetaldehyde is solely a response of the peroxisomal enzyme as evidenced by its insensitivity to N-ethylmaleimide and 5 mM glycerol 3-phosphate. Furthermore, microsomal dihydroxyacetone phosphate acyltransferase activity is inhibited at all acetaldehyde concentrations. The activation of membrane-bound DHAP acyltransferase by acetaldehyde appears to be specific for this enzyme in comparison to several other peroxisomal and microsomal enzymes. The specificity of activation and differential response of the peroxisomal enzyme to acetaldehyde indicates that the microenvironment of the peroxisomal membrane is important for normal enzymatic function of this enzyme. | Dihydroxyacetone phosphate acyl transferase (DHAP-AT), alkyl dihydroxyacetone phosphate synthase (alkyl- DHAP-synthase), and glycerol-3-phosphate acyltransferase (GPAT) activities were investigated under optimal assay condi- tions using highly purified organelle preparations. The data presented clearly indicate that GPAT activity was mainly local- ized in mitochondria and microsomes, whereas DHAP-AT and alkyl-DHAP-synthase activities were exclusively localized in peroxisomes. A small fraction of the total DHAP-AT and alkyl- DHAP-synthase activities observed in purified mitochondrial preparations was due to the presence of intact peroxisomes. DHAP-AT and alkyl-DHAP-synthase activities were very low in purified microsomes (< 1% compared to peroxisomes) and these activities are thought to be due to sedimentation of perox- isomal fragments (generated during homogenization of liver and processing of liver homogenate) with microsomes. The results indicate that the dihydroxyacetone phosphate pathway does not contribute to the synthesis of glycerolipids other than ether lipids in rat liver. The ether bond formation occurs exclu- sively in peroxisomes, and all the biosynthetic reactions for plas- malogen synthesis may also be operating within peroxisomes in rat liver.-Singh, H., K. Beckman, and A. Poulos. Exclusive localization in peroxisomes of dihydroxyacetone phosphate acyltransferase and alkyl-dihydroxyacetone phosphate synthase in rat liver. J. Lipid Res. 1993. 34: 467-477. | Dihydroxyacetone phosphate acyl transferase (DHAP-AT), alkyl dihydroxyacetone phosphate synthase (alkyl- DHAP-synthase), and glycerol-3-phosphate acyltransferase (GPAT) activities were investigated under optimal assay condi- tions using highly purified organelle preparations. The data presented clearly indicate that GPAT activity was mainly local- ized in mitochondria and microsomes, whereas DHAP-AT and alkyl-DHAP-synthase activities were exclusively localized in peroxisomes. A small fraction of the total DHAP-AT and alkyl- DHAP-synthase activities observed in purified mitochondrial preparations was due to the presence of intact peroxisomes. DHAP-AT and alkyl-DHAP-synthase activities were very low in purified microsomes (< 1% compared to peroxisomes) and these activities are thought to be due to sedimentation of perox- isomal fragments (generated during homogenization of liver and processing of liver homogenate) with microsomes. The results indicate that the dihydroxyacetone phosphate pathway does not contribute to the synthesis of glycerolipids other than ether lipids in rat liver. The ether bond formation occurs exclu- sively in peroxisomes, and all the biosynthetic reactions for plas- malogen synthesis may also be operating within peroxisomes in rat liver.-Singh, H., K. Beckman, and A. Poulos. Exclusive localization in peroxisomes of dihydroxyacetone phosphate acyltransferase and alkyl-dihydroxyacetone phosphate synthase in rat liver. J. Lipid Res. 1993. 34: 467-477. | eng_Latn | 27,258 |
A derivative spectrophotometric method has been developed for quantitative determination of p-coumaric and ferulic acid6 in mixtures. A detailed study of experimental variables and instrumental parameters was carried out. This paper reports the testing of a graphical model to measure derivative amplitudes which is based on the interference-free character of the isodifferential points in the derivative calibration graphs. Detection limits of 20 and 50 ng/ml and r.s.d.'s of 0, 63 % and 1, 73 % were found for p-coumaric and ferulic acids, respectively. | Vanillin (4-hydroxy-3-methoxybenzaldehyde) and p-hydroxybenzaldehyde were determined by spectrophotometric derivative measurements in vanilla bean extracts. The method tolerates p-hydroxybenzaldehyde to vanillin ratios of 3:l (w/w) with relative error below 5% in the determination of vanillin. This method compares favorably with the official AOAC spectrophotometric procedure. Relative errors of 0.70% and RSD's of 1.0% are obtained. The importance of vanillin for the flavor industry and, consequently, its economic implications justify the numerous analytical criteria proposed for the determination of this and other compounds present in it. Moreover, the amount of vanillin found in vanilla extracts is an index as much of the product quality as of its origin. One author showed a correlation between the vanillin and phydroxybenzaldehyde ratio contained in vanilla beans in relation to their geographical origin (Juergens, 1981a). | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,259 |
Phycobiliproteins are homologous chromoproteins which constitute the phycobilisomes, the light harvesting complexes of the photosynthetic apparatus in cyanobacteria, rhodophyta and cryptophyta. In the present work, phycocyanin (PC) and Phycoerythrin (PE) from a Nostoc species are proposed as protein markers for electrophoretic techniques. Phycocyanin is a blue-colored phycobiliprotein; it carries phycocyanobilin as chromophoric group and is composed of two subunits, α and β, with Mr of 14000 and 17000, respectively. In contrast, the PE subunits, having a similar Mr of 21000, are deep rose chromoproteins and carry phycoerythrobilin residues. Both low molecular weight phycobiliproteins are also suitable for monitoring protien blotting and the focusing time of protein samples during isoelectric focusing as internal markers. The PE subunits which form a single broad band after sodium dodecyl sulfate-polyacrylamide gel electrophoresis have different isoelectric points, and they form two visible bands when they reach their isoelectric point. The phycobilisomes constitute up to 50% of the total protein in cyanobacteria and their content in PC or PE can be up- or down-regulated by using different light conditions (chromatic adaptation). | The paper reports an efficient procedure for the extraction and purification of R-phycoerythrin (R-PE) from marine red algae Amphiroa anceps. A. anceps was extracted in 50 mM phosphate buffered saline and precipitated by (NH4)2SO4. The R-PE was isolated by ion-exchange chromatography loaded with Q-Sepharose Fast Flow, which was developed by linear ionic strength gradients. Then it was purified by gel filtration Sepharose CL-6B column chromatography. SDS-PAGE showed the presence of two major subunits with 18 kDa and 20 kDa, respectively, and a minor subunit of 30 kDa. The observations are consistent with the (αβ)6γ subunit composition characteristic of R-PE. The absorption spectrum of R-PE was characterized by three absorbance maxima at 563, 538 and 495 nm, respectively, and the fluorescence emission spectrum at room temperature was 580 nm. Furthermore, R-PE showed good stability between pH 3.5 and 9.5. However, under oxidative conditions R-PE lost its shining. The results indicate that using ion-exchange chromatography with Q-Sepharose and gel filtration Sepharose CL-6B chromatography, R-PE can be purified on large scale from the red alga A. anceps. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,260 |
A method is presented which allows the identification and assay of a nucleoside in the presence of other analogues and homologues. The method is based on the conventional multiple reaction monitoring approach performed on the [M + H]+ ions of wild-type and modified nucleosides produced by the turbo ionspray ionization method on a triple-quadrupole mass spectrometer. The accuracy of the quantitative determination relies on the evaluation of a response factor ρ, which takes into account the kinetics of dissociation of the parent ions into the protonated [B + 2H]+ nucleobase ions. The evaluation of the absolute concentration of each analyte in the examined mixture does not require any previous chromatographic separation. Copyright © 2003 John Wiley & Sons, Ltd. | An evaluation of the gas-phase ion chemistry of rotenone (1) by electrospray ionisation (ESI) mass spectrometry (MS) and tandem mass spectrometry (MS2) is presented, aiming at providing tools for its determination in natural and biological matrices. The behaviour of its cycloadducts with benzonitrile-N-oxide (2) and 2,4,6-trimethylbenzonitrile-N-oxide (3) was also evaluated and the MS data thus obtained have provided evidence into the mechanism of formation of the key product ion at m/z 192 which can be considered a marker in the MS and MS2 spectra of rotenone and its derivatives. | The reduction of proline by Clostridium sporogenes NCIB8053 is coupled to transmembrane proton translocation in an uncoupler-sensitive fashion (and might therefore conserve free energy). This finding serves to explain the increase in the growth yield of this organism when proline is added to a defined growth medium containing glucose as the catabolic substrate. | eng_Latn | 27,261 |
High-resolution magic angle spinning (MAS) (1)H NMR spectra of small samples (ca. 8 mg) of intact rat liver are reported for the first time. One dimensional spectra reveal a number of large well-resolved NMR signals mainly from low to medium molecular weight compounds (generally <1000 Daltons) from a variety of chemical classes. A range of 2D MAS-NMR experiments were performed, including (1)H J-resolved (JRES), (1)H-(1)H total correlation spectroscopy (TOCSY) and (1)H-(13)C heteronuclear multiple quantum coherence (HMQC) to enable detailed signal assignment. Resonances were assigned from alpha- and beta-glucose, glycerol, alanine, glutamate, glycine, dimethylglycine, lysine, and threonine, together with phosphocholine, choline, lactate, trimethylamine-N-oxide (TMAO), and certain fatty acids. Well-resolved (1)H NMR signals from glycogen (poly 1-4 alpha-glucose) were observed directly in intact liver using MAS-NMR spectroscopy. In addition, the resonances from the glycogen C(1)H proton in alpha(1-->4) linked glucose units with either alpha(1-->4) units adjacent or alpha(1-->6) linked branches could be resolved in a high-resolution (1)H NMR experiment giving direct in situ information on the ratio of alpha(1-->4) to alpha(1-->6) units. This indicates that despite the relatively high MW (>1,000,000 Daltons) there is considerable segmental motion in the glycogen molecules giving long (1)H T(2) relaxation times. Magn Reson Med 44:201-207, 2000. | High-resolution NMR spectra of materials subject to anisotropic broadening are usually obtained by rotating the sample about the magic angle, which is 54.7 degrees to the static magnetic field. In projected magic angle spinning (p-MAS), the sample is spun about two angles, neither of which is the magic angle. This provides a method of obtaining isotropic spectra while spinning at shallow angles. The p-MAS experiment may be used in situations where spinning the sample at the magic angle is not possible due to geometric or other constraints, allowing the choice of spinning angle to be determined by factors such as the shape of the sample, rather than by the spin physics. The application of this technique to bovine tissue samples is demonstrated as a proof of principle for future biological or medical applications. | MLL1 regulates circadian promoters by depositing H3K4 trimethyl marks, whose levels are also modulated by the NAD+-dependent deacetylase SIRT1. SIRT1 is now shown to promote circadian deacetylation of MLL1, thus affecting MLL1's methyltransferase activity. | eng_Latn | 27,262 |
Filamentous green algae (FGA) frequently forms dense mats which can be either mono- or polyspecies. While various defense mechanisms of competition in algae are known, little is known about the interactions between different species of FGA. An experiment in controlled laboratory conditions was conducted to gather data on the changes in amino acids (AA) concentrations in FGA species in the presence of exudates from different other species. The aim of the present study was to identify the AA whose concentrations showed significant changes and to assess if the changes could be adaptation to stress conditions. The major constituents of the AA pool in Cladophora glomerata, C. fracta and Rhizoclonium sp. were Glutamic acid (Glu), Aspartic acid (Asp) and Leucine (Leu). In response to chemical stress, that is the increasing presence of exudates, a significant increase in the concentrations Proline (Pro) and Tryptophan (Trp) was noted. The increase in Proline levels was observed in C. fracta and Rhizoclonium in response to chemical stress induced by C. glomerata exudates. As the concentration of exudates increased in the medium, there was a progressive shift in the pattern of AA group in FGA. | Diurnal patterns of photosynthesis were studied in July and April populations of Cladophora glomerata (L.) Kutz. from open and from shaded sites. Summer samples exposed to full sunlight showed decreased efficiency of open photosystem II at noon, and only slight differences were found between samples that had grown at open or at shaded sites. Electron transport rate was limited at highest fluence rates in shade plants, and non-photochemical quenching (NPQ) revealed faster regulation in samples from open sites. Daily course of de-epoxidation was not linearly correlated with the course of NPQ. The comparison of samples from open and from shaded sites revealed a higher capacity of thermal energy dissipation and an increase in the total amount of xanthophyll-cycle pigments (21%) in samples from open sites. In April, down-regulation of the efficiency of open photosystem II was related to lower water temperature, and hence, increased excitation pressure. In April the pool size of xanthophyll-cycle pigments was increased by 21% in comparison with summer and suggested higher levels of thermal energy dissipation via de-epoxidized xanthophylls. In both, summer and spring the amount of xanthophyll-cycle pigments was 20% higher in samples from open sites. Acclimation of C. glomerata to growth light conditions was further shown by experimental induction of NPQ, indicating NPQ increases of 23%, and increases of 77% in the reversible component of NPQ in open site samples. The effect of temperature on photosynthetic rate was non-linear, and different optimum temperatures of electron transport rate and oxygen evolution were exhibited. | Purpose ::: This study was aimed to investigate the relationship between psychological and physiological changes and performance in archery, which is strongly influenced by psychological factors including concentration, tension, anxiety, and stress. ::: ::: ::: Methods ::: A total of 19 athletes from women's colleges who participated in the 30 m individual competition at the 34th President's Cup National Archery Competition in July 2016 were included in this study. The anxiety levels of the participants were assessed on a 10-point Likert scale, with 1 corresponding to "not at all" and 10 to "extremely anxious." Saliva samples were collected as follows: 10 min before the game (pre-10), 1 min before the game (pre-1), and 10 min after the game (post-10). Repeated measures general linear model ANOVA was performed to compare the mean values of salivary alpha amylase (sAA) concentrations and anxiety levels. The correlations between sAA, anxiety, and game records were analyzed using the Pearson's correlation method. ::: ::: ::: Results ::: The sAA concentrations increased significantly in pre-1 and post-10, but not in pre-10 samples. Moreover, anxiety levels increased in both pre-1 and post-10 samples, but not in pre-10 samples. Anxiety and sAA were positively correlated (p < 0.01), while sAA and game records, or anxiety and game record were negatively correlated (p < 0.01). ::: ::: ::: Conclusion ::: During the archery competition, the level of cognitive anxiety increased, sAA concentrations increased, and performance decreased. The study findings suggest that during archery competitions, anxiety hinders performance, and this effect may be related to the increase in sAA levels. | eng_Latn | 27,263 |
The antioxidant and scavenging activities of above ground parts of Equisetum arvense L., Equisetum ramosissimum L. and Equisetum telmateia L. phosphate buffer (pH 7) extracts were investigated. Activities of antioxidant enzymes (superoxide dismutase, catalase, guaiacol peroxidase and glutathione peroxidase), quantities of reduced glutathione, malonyldialdehyde, superoxide and hydroxyl radicals and flavonoid, soluble protein, chlorophyll a, b and carotenoid contents were determined. The total antioxidant capacity was determined by ferric reducing antioxidant power (FRAP) assay. The Equisetum telmateia extract demonstrated scavenging and antioxidant properties better than Equisetum ramosissimum and Equisetum arvense. The ESR signal of DMPO-OH radical adducts in the presence of Equisetum telmateia phosphate buffer (pH 7) extract was reduced by 98.9% indicating that Equisetum telmateia could be a useful source of antioxidants with huge scavenging ability. Copyright © 2008 John Wiley & Sons, Ltd. | Objective: In this study the inhibitory effect of E. arvense extract on trypsin activity and the effect of trypsin on E. arvense extract were studied. In addition the nature of the interaction between the extract and trypsin was investigated. Methods: The inhibitory effect ethanol extract of E. arvense on trypsin activity was determined using trypsin enzyme assay. The structural effects of the extract-trypsin interaction for the extract were analyzed by FTIR. Finally, the HPLC analyses were carried out to analyze the individual components of the extract and the supernatant and soluble precipitate phases. Results: E. arvense extract was found to decrease total percent activity of trypsin to 5% in 24 hour at 24 °C. FTIR analyses indicated that the interaction between trypsin and E. arvense extract caused changes in the structure and hydrogen bonding behavior and composition of the extract proteins. These interactions also caused the extract lipids to accumulate in the insoluble precipitate phase. Most of the phenolics remained in the supernatant phase enhancing the inactivation of trypsin. However, the precipitated compounds were shown to be of apolar in nature as shown in the HPLC chromatograms. Conclusion: The methods that were used showed that the high phenolic content of E. arvense was the main reason for the inhibition of trypsin enzyme activity by denaturing the enzyme. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,264 |
A mass was identified within the left lateral lobe of the liver of a 10-year-old Eurasian badger (Meles meles). The mass was friable and multilobulated, with blood-filled spaces between the lobules. Microscopically, the lesion consisted of sheets and trabeculae of neoplastic hepatocytes often forming cystic spaces containing erythrocytes, fibrin and necrotic debris. The histological appearance was consistent with hepatocellular carcinoma (HCC). Immunohistochemically, the neoplastic cells expressed cytokeratin 18 but not von Willebrand factor. Multiple intranuclear (amphophilic or acidophilic) inclusion bodies were observed in hepatocytes at the junction between the tumour and normal hepatic tissue. HCCs have also been reported in other domestic and wild animals. As hepadnavirus infection has been associated with HCC in woodchucks, further histochemical and transmission electron microscopical studies were performed; however, these demonstrated that the inclusions consisted of lipid droplets and not viral particles. To our knowledge, this is the first report of a naturally occurring HCC in a Eurasian badger. | Hepatocellular carcinoma was diagnosed in five slender tailed meerkats (Suricata suricatta) housed at the Smithsonian Institution's National Zoological Park between 1980 and 2013. Animals included four females and one male, ranging from 7 to 15 yr of age. Common clinical signs included weight loss and lethargy. Three of the neoplasms originated from the right medial liver lobe and were located adjacent to or partially incorporated in the gall bladder. Three animals had solitary masses, and two animals had multiple hepatic masses; all were characterized by polygonal to round neoplastic hepatocytes arranged in a trabecular pattern with smaller regions of varied solid, adenoid, and rarely peliod cell patterns. Hemorrhage and necrosis often with cystic degeneration was noted in all five cases. There was no evidence of metastatic disease in any of the cases examined. | Beta-cyclodextrin polymers (pbCD) cross-linked by epichlorohydrin (pbCDE) and citric acid (pbCDC) were prepared in this work. The inclusion complexes of pbCDE and pbCDC with curcumin and two commercial UV filters, 2-ethylhexyl-p-methoxycinnamate (EHMC) and 4-tert-butyl-4′-methoxydibenzoylmethane (DBM) were investigated. The UV absorption of these three compounds observed in water indicated that the water solubility of these three hydrophobic compounds increased. The amount of EHMC was higher in both pbCDE and pbCDC than curcumin and DBM, respectively. The photostability of these three compound inclusion complexes with pbCDE and pbCDC were also studied in water and ethylene glycol. It was found that the photostability of the three compounds improved upon formation of the inclusion complex with pbCDE in an aqueous and ethylene glycol solution. The acidity of the crosslink moiety effects to the inclusion complex formation and the photostability of the guests suggesting that more acidity of citric acid decreased the formation and stability of all guest compounds. | eng_Latn | 27,265 |
Ochratoxin A (OTA), a naturally occurring mycotoxin of Aspergillus and Penicillium species, consists of a 5' chlorinated dihydromethyl isocoumarin linked to L,beta-phenylalanine by an alpha-amide bond. 8 analogues of OTA were prepared in which the phenylalanine was always substituted by another amino acid. The effects of these analogues on yeast tRNA amino acylation reaction and on growth and protein synthesis of hepatoma culture cells were compared with those of OTA. In addition, Ochratoxin B (OTB) and ochratoxin alpha (OT alpha) were examined. All the analogues of OTA had inhibitory effects in the 3 test systems, although to a lesser degree than OTA. The degree of inhibition depended on the kind of substituted amino acid, the tyrosine, valine, serine and alanine analogues being most effective, in contrast to the proline analogue. OTB and OT alpha were ineffective. | The transport of the nephrotoxic mycotoxin ochratoxin A across the renal peritubular membrane was examined in suspensions of rabbit renal proximal tubules. Ochratoxin A transport across the peritubular membrane was a high-affinity, low-capacity carrier-mediated process with a Jmax value of 0.12 +/- 0.4 nmol/mg of protein/min and a Km value of 1.4 +/- 0.1 microM. The apparent Michaelis constants for inhibition of [3H]para-aminohippurate (PAH) uptake by ochratoxin A inhibition was 1.5 microM, which is similar to the Km value for ochratoxin A uptake in tubule suspensions and suggests that ochratoxin A could be a substrate for the organic anion pathway. The capacity and affinity for peritubular ochratoxin A transport were 40-fold lower and > 100-fold greater, respectively, than those measured for the peritubular uptake of [3H]PAH in tubule suspensions. A concentration of 2.5 mM PAH, which reduced the uptake of [3H]PAH by 90%, reduced ochratoxin A uptake by only 40% to 50%, whereas probenecid concentrations of 0.6 to 2 mM reduced ochratoxin A accumulation in tubule suspensions up to approximately 80% to 90%. This probenecid-sensitive, PAH-insensitive uptake of ochratoxin A suggested that at least one mediated pathway other than the organic anion transporter was involved in the peritubular uptake of this mycotoxin. A 2 mM concentration of the fatty acid octanoate and 1.5 mM concentration of the nonsteroidal anti-inflammatory agent piroxicam were as effective as probenecid in blocking ochratoxin A uptake. The apparent Ki values for inhibition of ochratoxin A uptake by probenecid, piroxicam and octanoate were 30.5 +/- 7.9, 23.2 +/- 10.4 and 81.5 +/- 8.7 microM, respectively. The ability of octanoic acid to inhibit ochratoxin A transport to the same extent as probenecid and a greater extent than PAH suggests that a separate fatty acid transport pathway may be involved in the accumulation of ochratoxin A by suspensions of rabbit renal proximal tubules. | A novel fully symmetric chopper operational transconductance amplifier (OTA) design is presented. This OTA concept improves the indirect chopper OTA design presented in a former paper in respect of higher CMRR, PSRR, clock feed through immunity and an increased slew rate. This amplifier is wholly realizable on silicon. | eng_Latn | 27,266 |
Enzymatic microcalorimetry has been successfully employed in the reliable determination of the l-malic acid concentration in some foods and cosmetic products. The l-malic acid concentration during the wine-making process is particularly useful in order to control the progress of the malo-lactic fermentation. Total acidity, taste and flavour characteristics of wine depend on the l-malic acid quantity still present. To point out the analytical methodology the dehydration process of l-malic acid, in the presence of Fumarase enzyme, has been used. The new method has been compared with a common spectrophotometric one. By the proposed calorimetric method the l-malic acid concentration in different types of food (white and red wines, fruits and soft beverages) has been determined. In some cosmetic products too the l-malic acid was quantified. The method outlined resulted simple, direct and reliable (good accuracy and precision), in particular it does not require any pre-treatment or clean up of the samples, save the dilution in buffer. | A synchronized calorimetric and spectrophotometric method for measuring enzymatic reaction enthalpy was described. The spectrophotometric method was used to determine the amounts of reactant or product changes during the reaction, and calorimetry was used to determine the thermal changes associated with the reaction. Both methods used a same reaction system to simultaneously measure the progress of reaction. By the synchronized calorimetric–spectrophotometric determination, enthalpy values were obtained as 92.17 ± 3.06 kJ mol−1 by the initial velocity calculation method and 100.9 ± 1.81 kJ mol−1 by the steady-state calculation method for a catalase-catalyzed hydrogen peroxide reaction at 298.15 K and pH 7.0. When comparing with the theoretical values, the results showed that the synchronized method with the steady-state method was in alignment and demonstrated greater stability. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,267 |
A sensitive and simple high performance liquid chromatography (HPLC) method was developed and validated for the determination of thalidomide in rat plasma. Chromatography was accomplished with a reversed-phase Hypersil C18 column. Mobile phase consisted of acetonitrile-10 mM ammonium acetate buffer (pH 5.50) (28:72, v/v), at a flow rate of 0.8 ml/min. Thalidomide was monitored by ultraviolet detector at 220 nm and it gave a linear response as a function of concentration over 0.02-50 microM. The limit of quantitation in rat plasma was 0.50 ng (0.02 microM plasma concentration) with an aliquot of 20 microl. Results from a 3-day validation study indicated that this method allows for simple and rapid quantitation of thalidomide with excellent accuracy and reliability. Using this validated assay, the effect of coadministered irinotecan (CPT-11) on the plasma pharmacokinetics of thalidomide in rats was determined. Coadministration of CPT-11 (intravenously, 60 mg/kg) increased the maximum plasma concentration (C(max)) and area under the plasma concentration-time curve (AUC(0-10h)) of thalidomide by 32.29 and 11.66%, respectively, as compared to the control, but none of the effect of CPT-11 was of statistical significance (P > 0.05). Concomitant CPT-11 also caused a 10.04% decrease in plasma clearance (CL) and 14.51% decrease in volume of distribution (V(d)) (P > 0.05). These results suggest that coadministered CPT-11 did not significantly alter the plasma pharmacokinetics of thalidomide in rats. Further studies are warranted to explore the pharmacokinetic and pharmacodynamic interactions between CPT-11 and thalidomide. | A rapid, sensitive and specific analytical method based on high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the determination of thalidomide concentration in human plasma. The analyte and internal standard were extracted by liquid-liquid extraction with ether-dichloromethane (3:2, v/v) and separated on a TC-C18 column using methanol-10 mM ammonium acetate-formic acid (60:40:0.04, v/v/v) as the mobile phase at a flow rate of 0.9 ml/min. The detection was performed using an API 4000 triple quadrupole mass spectrometer in the positive electrospray ionization (ESI) mode and completed within 3.0 min. The multiple reaction monitoring (MRM) transitions were m/z 259.1→84.0 for the analyte and m/z 195.9→138.9 for temozolomide. The calibration curve exhibited a linear dynamic range of 2–1500 ng/ml (r>0.9991). The intra-and inter-day precisions (as relative standard deviation; RSD) were 6.8–13.5% and 4.3–5.0% respectively and the accuracy (as relative error; RE) was 2.0–3.5%. The recoveries and matrix effects were satisfactory in all the biological matrices examined. This method was successfully used in a pharmacokinetic study of thalidomide in healthy male volunteers receiving an oral administration of a 200-mg dose. | not available DOI: http://dx.doi.org/10.3329/pulse.v5i2.20263 Pulse Vol.5 July 2011 p.31-40 | eng_Latn | 27,268 |
Acylation reactions are ubiquitous in the synthesis of natural products and biologically active compounds. Unfortunately, these reactions often require the use of large quantities of volatile and/or toxic solvents, either for the reaction, purification or isolation of the products. Herein we describe and discuss the possibility of completely eliminating the use of organic solvents for the synthesis, purification and isolation of products resulting from the acylation of amines and other nucleophiles. Thus, utilisation of N,N'-carbonyldiimidazole (CDI) allows efficient coupling between carboxylic acids and various nucleophiles under solvent-free mechanical agitation, and water-assisted grinding enables both the purification and isolation of pure products. Critical parameters such as the physical state and water solubility of the products, milling material, type of agitation (vibratory or planetary) as well as contamination from wear are analysed and discussed. In addition, original organic-solvent-free conditions are proposed to overcome the limitations of this approach. The calculations of various green metrics are included, highlighting the particularly low environmental impact of this strategy. | A unique synthetic approach to 3-hydroxy-4-substituted picolinonitriles is achieved via gold(I)-catalyzed cyclization of 4-propargylaminoisoxazoles and subsequent N-O bond cleavage of isoxazolopyridines under mild reaction conditions in a stepwise and one-pot fashion. | Different analytical (enzyme system and near-infrared spectroscopy (NIRS)) and statistical (single and multiple regressions) approaches were used to predict in vivo standardized pre-caecal digestibility (PCD) of crude protein (CP) and amino acids (AA) in cereal grains for growing pigs as well as in vitro nitrogen (N) solubility. Furthermore, different chemical and physical characteristics were categorized (e.g. crude nutrients, AA, minerals, fibre components or combinations of these) and used for generating prediction equations. There were strong linear relationships (p < .05) between in vivo PCD of CP and essential AA and in vitro N solubility when grain species was considered as covariate in the model. Predicting in vivo PCD values using various chemical and physical characteristics produced inconsistent results among different grain species and AA and could therefore not be used for predicting PCD. It is possible to predict in vitro N solubility from chemical and physical characteristics for some grain species. However, the relationships between some of these categories and the in vitro N solubility were not consistent and not always causative or physiologically explainable. The R2 of NIRS for predicting in vitro N solubility was at a relatively high level (up to R2 = 0.80). This level of R2 indicates that a classification of the grain samples in, for example, high, medium and low in vitro N solubility levels is possible, but it does not allow for a quantitative prediction of the in vitro N solubility. In conclusion, the present database can be used for establishing a ranking of different cereal grain species for PCD of CP and essential AA values. However, it was not possible to create clear prediction equations for in vivo or in vitro digestibility values. Therefore, greater variation within grain species, for example due to different growing and harvesting conditions, is warranted for predicting PCD values of individual grain samples. | eng_Latn | 27,269 |
For years it has been suspected that natural hormones are illegally used as growth promoters in cattle in the European Union. Unfortunately there is a lack of methods and criteria that can be used to detect the abuse of natural hormones and distinguish treated from non-treated animals. Pattern recognition of steroid profiles is a promising approach for tracing/detecting the abuse of natural hormones administered to cattle. Traditionally steroids are analysed in urine as free steroid after deconjugation of the glucuronide (and sulphate) conjugates. The disadvantage of this deconjugation is that valuable information about the steroid profile in the sample is lost. In this study we develop a method to analyse steroids at very low concentration levels (ng l−1) for the free steroid, glucuronide and sulphate conjugates in urine samples. This method was used to determine concentrations of natural (pro)hormones in a large population (n = 620) of samples from male and female bovine animals and from bovine animals ... | Profiling conjugated urinary steroids to detect anabolic-steroid misuse is recognized as an efficient analytical strategy in both chemical-food-safety and anti-doping fields. The relevance and robustness of such profiling rely on the analysis of glucuronide and sulfate steroids, which is expected to have properties including accuracy, specificity, sensitivity, and, if possible, rapidity. In this context, the ability of ultra-high-performance supercritical-fluid chromatography (UHPSFC) hyphenated tandem mass spectrometry (MS-MS) to provide reliable and accurate phase II analysis of steroids was assessed. Four stationary phases with sub-2 μm particles (BEH, BEH 2-ethyl-pyridine, HSS C18 SB, and CSH fluorophenyl) were screened for their capacity to separate several conjugated steroid isomers. Analytical conditions including stationary phase, modifier composition and percentage, back pressure, column temperature, and composition and flow rate of make-up solvent were investigated to improve the separation and/or the sensitivity. Thus, an analytical procedure enabling the analysis of eight glucuronide and 12 sulfate steroids by two different methods in 12 and 15 min, respectively, was optimized. The two procedures were evaluated, and UHPSFC-MS-MS analysis revealed its ability to provide sensitive (limits of quantification: 0.1 ng mL(-1) and 0.5 ng mL(-1) for sulfate and glucuronide steroids, respectively) and reliable quantitative performance (R(2) > 0.995, RSD < 20%, and bias < 30%) through the use of suitable labeled internal standards. Comparison with UHPLC-MS-MS was performed, and UHPSFC-MS-MS obtained better performance in terms of sensitivity. Finally, as a proof of concept, this so-called green technology was used in a chemical-food-safety context to profile steroid conjugates in urine samples from bovines treated with estradiol. Graphical Glucuronide and sulfate steroids analysis in urine by ultra-high performance supercritical fluid chromatography hyphenated tandem mass spectrometry. | Microwave devices with the Rollet parameter (k) less than one can always be made stable by resistive loading. In cases where noise figure or output power is at a premium, the performance of an amplifier can often be enhanced by using a design where k is less than unity thereby avoiding resistive loading. While a simultaneous conjugate match is impossible for such conditionally stable designs, single-sided matching can be achieved. Low-noise and power designs are examples where single-sided matching considerations naturally occur. With single-sided matching and 0 > | eng_Latn | 27,270 |
Ebastine (CAS 90729-43-4) is an antiallergic agent which selectively and potently blocks histamine H1-receptors in vivo. A simple and sensitive high-performance liquid chromatography (HPLC) method is described for the simultaneous determination of ebastine and its two oxidized metabolites, carebastine (CAS 90729-42-3) and hydroxyebastine (M–OH), in human plasma. After a pretreatment of plasma sample by solid-phase extraction, ebastine and its metabolites were analyzed on an HPLC system with ultraviolet detection at 254 nm. Chromatography was performed on a cyano column (250×4.0 mm I.D.) at 40 °C with the mobile phase of acetonitrile–methanol–0.012 M ammonium acetate buffer (20:30:48, v/v/v) at a flow rate of 1.2 ml/min. Accurate determinations were possible over the concentration range of 3–1000 ng/ml for the three compounds using 1 ml plasma samples. The intra- and inter-day assay accuracy of this method were within 100±15% of nominal values and the precision did not exceed 12.4% of relative standard deviation. The lower limits of quantitation were 3 ng/ml for ebastine and its metabolites in human plasma. This method was satisfactorily applied to the determination of ebastine and its two oxidized metabolites in human plasma after oral administration of ebastine. | A validated simple, rapid, and selective spectrofluorimetric method was developed for the determination of some antihistaminic H1 receptor antagonist drugs namely ebastine (EBS), cetirizine dihydrochloride (CTZ), and fexofenadine hydrochloride (FXD). The method is based on the reaction of the cited drugs with some Π acceptors namely p-chloranilic acid (CLA), tetracyanoethylene (TCNE), and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) to give highly fluorescent derivatives. The fluorescence intensity—concentration plots were rectilinear over the concentration ranges of 0.2–3.0, 0.2–2.5 and 0.15–2.0 μg/ml for EBS with CLA, DDQ, and TCNE respectively; 0.5–7.0, 0.5–6.0, and 0.2–4.0 μg/ml for CTZ with the previously mentioned reagents, and 0.2–3.5, 0.5–6.0, and 0.2–3.5 μg/ml for FXD. The factors affecting the formation of the reaction products were carefully studied and optimized. The method was applied for the determination of the studied drugs in their dosage forms. The results obtained were in good agreement with those obtained by the comparison methods. Reactions Stoichiometries of the complexes formed between the studied drugs and Π acceptors were defined by the Job’s method of the continuous variation and found in 1:1 in all cases. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,271 |
DL-Threo-3,4-dihydroxyphenylserine (DL-DOPS) was given to six subjects with severe orthostatic hypotension (OH). On separate days each subject took either 600 or 800 mg DL-DOPS or placebo. DL-DOPS increased norepinephrine (NE) excretion 10,000% and urinary normetanephrine and dihydroxyphenylglycol excretion 400%. DL-DOPS, however, led to only slight increases in excretion of the major NE metabolites 3-methoxy-4-hydroxyphenylglycol and vanillylmandelic acid. Only approximately 2.2% +/- 0.5% (range 0.65% to 3.8%) of the L-stereoisomer (L-DOPS), when given as DL-DOPS, is converted to NE in vivo over 24 hr. DL-DOPS did not affect either supine or upright blood pressure in our subjects. Our findings do not support reports that DL-DOPS may be therapeutically useful in OH. | A group of amnesic patients with Korsakoff's disease were treated with a single 1 g dose of dl-threo-3,4-dihydroxyphenylserine (DOPS) and placebo (lactose) in a double-blind crossover study. Three hours following administration, patients were given a battery of psychometric tests to determine the effects of the treatment on memory functions. Administration of DOPS had a significant effect on performance on the Memory Passages test but not on any of the other measures of memory. The effect of DOPS on Memory Passages is similar to the response observed following administration of clonidine in Korsakoff patients. Blood pressure and pulse, measured before and every 2 h after treatment, were unaffected by DOPS. | Polyamines (PAs) are natural compounds involved in many growth and developmental processes in plants, and, specifically in fruits, play a vital role regulating its development, ripening and senescence processes. Putrescine (PUT), spermine (SPE), and spermidine (SPD) are prominent PAs applied exogenously to extend shelf life of fruits. They also originate endogenously during developmental phases of horticultural crops and simultaneously affect the quality attributes and shelf life. Their anti-ethylene nature is being exploited to enhance the shelf life when exogenously applied on fruits. In growth and development of fruits, PA levels generally fall, which marks the beginning of senescence at postharvest phase. PUT, SPE and SPD treatments are being applied during postharvest phase to prolong the shelf life. They enhance the shelf life of fruits by reducing respiration rate, ethylene release and enhance firmness and quality attributes in fruits. PAs have a mitigating impact on biotic and abiotic stresses including chilling injury (CI) in tropical and sub-tropical fruits. PAs are environment friendly in nature and are biodegradable without showing any negative effect on environment. Biotechnological interventions by using chimeric gene constructs of PA encoding genes has boosted the research to develop transgenic fruits and vegetables which would possess inherent or in situ mechanism of enhanced biosynthesis of PAs at different stages of development and thereby will enhance the shelf life and quality in fruits. Internal and external quality attributes of fruits are improved by modulation of antioxidant system and by strengthening biophysical morphology of fruits by electrostatic interaction between PAs and phospholipids in the cell wall. | eng_Latn | 27,272 |
Hydrogen sulfide (H2S) is the last gaseous transmitter identified in mammals and previous studies have reported disparate conclusions regarding the implication of H2S in cancer progression. In the present study, we hypothesized that NaHS, a fast H2S-releasing donor, might interfere with the mitochondrial respiratory chain of tumor cells, increase tumor oxygenation and potentiate the response to irradiation. Using EPR oximetry, we found a rapid increase in tumor pO2 after NaHS administration (0.1 mmol/kg) in two human tumor models (breast MDA-MB-231 and cervix SiHa), an effect that was due to a decreased oxygen consumption and an increased tumor perfusion. Tumors irradiated 15 minutes after a single NaHS administration were more sensitive to irradiation compared to those that received irradiation alone (increase in growth delay by 50%). This radiosensitization was due to the oxygen-effect as the increased growth delay was abolished when temporarily clamped tumors were irradiated. In contrast, daily NaHS injection (0.1 mmol/kg/day for 14 days) did not provide any effect on tumor growth in vivo. To understand these paradoxical data, we analyzed the impact of external factors on the cellular response to NaHS. We found that extracellular pH had a dramatic effect on the cell response to NaHS as the proliferation rate (measured in vitro by BrdU incorporation) was increased at pH=7.4, but decreased at pH=6.5. Overall, our study highlights the complex role of environmental components on the response of cancer cells to H2S and suggests a new approach for the use of H2S donors in combination with radiation therapy. | Tumor hypoxia influences the outcome of treatment with radiotherapy, chemotherapy and even surgery, not only for the treatment of large bulky tumors with extensive necrosis, but also in the treatment of very small primary tumors and recurrences, micrometastases, and surgical margins with microscopic tumor involvement. Because hypoxic tumor cells are resistant to radiation and to many anticancer drugs, many approaches to circumventing the therapeutic resistance induced by hypoxia have been examined in laboratory studies and clinical trials. In this review, these approaches and the results of past laboratory and clinical studies are described and the limitations of the past agents and their testing are discussed. We describe the importance of new technologies for measuring hypoxia in human tumors, which allow assessment of pretreatment tumor oxygen levels and changes in hypoxia over the course of prolonged treatment regimens. These offer the possibility of improving the design of clinical trials and the selection of patients who will benefit from hypoxia-directed therapies, as well as the possibility of facilitating the development of better agents and regimens for use in hypoxia-directed therapy. We also discuss how the improved understanding of the abnormal vascular beds in solid tumors and of the effects of hypoxia and related microenvironmental insults, resulting from recent and ongoing research, offers the potential for finding new therapeutic targets, that may lead to the development of new agents and novel therapeutic approaches for selectively targeting cells in the adverse microenvironments within solid tumors. | Lead (Pb) is a widespread ecosystem pollutant and affects food security and public health. Hydrogen sulfide (H2S) plays prominent roles in mediating a variety of responses to stresses. The effects of sodium hydrosulfide (NaHS), a fast releaser of H2S, on cauliflower (Brassica oleracea L. var botrytis L. cv. Xiahua 60 d) seed germination and seedling growth under lead acetate stress were investigated in the present study. Pb (0.25 and 0.5 mM) stresses markedly inhibited seed germination and seedling growth, whereas the inhibition was effectively mitigated by NaHS application. Germination percentage, root length, shoot length, and fresh weight of single seedling significantly increased. In addition, NaHS elevated endogenous H2S contents and reduced malonyldialdehyde, superoxide anion (\({\text{O}}_{\text{2}}{\cdot}^ -\)), and hydrogen peroxide (H2O2) production, thereby preventing oxidative damage from Pb or Pb and antioxidant enzyme inhibitor (diethyldithiocarbamate or 3-amino-1,2,4-triazole) dual stresses. The protective roles of NaHS were equivalent to the ROS scavengers, 4,5-dihydroxy-1,3-benzene disulfonic acid? and N,N′-Dimethylthiourea. Moreover, NaHS elevated non-protein thiols and total glutathione levels to chelate Pb or scavenge ROS directly. Our results demonstrated the strong protective and antioxidant roles of H2S. | eng_Latn | 27,273 |
Drosophila melanogaster has been a widely used as a model system for its powerful genetic tools. However, it remains to be illustrated if Drosophila can be used to examine the biochemical and physiological metabolism of eicosanoids. Thus, the analysis on the metabolism of C20 polyunsaturated fatty acids (PUFA) in Drosophila was implemented with high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Fatty acid (FA) analysis of the whole body, head, and thorax-abdomen in Drosophila showed C20 PUFA could only be found in Drosophila fed diets supplemented with eicosapentaenoic acid (EPA) and arachidonic acid (ARA), but not in Drosophila fed base diets. The C20 PUFA were found in abundance in the head. Drosophila fed ARA- and EPA-supplemented diets yielded 15S-hydroxy-5Z,8Z,11Z,13E-eicosatetraenoic acid [15(S)-HETE] and 15S-hydroxy-5Z,8Z,11Z,13E,17Z-eicosapentaenoic acid [15(S)-HEPE], respectively, while other sampled eicosanoids could not be detected. Similar results were obtained by incubating fly tissue supplemented with ARA or EPA. Furthermore, a genome sequence scan indicated that no gene encoding the key enzymes synthesizing eicosanoids were found in Drosophila. These findings demonstrate that Drosophila may possess a special lipid metabolic system, which is different from mammals. | Prostaglandins, well-known lipid mediators in vertebrate animals, have also shown to play certain regulatory roles in insects and other arthropods acting on reproduction, immune system and ion transport. However, knowledge of their biosynthetic pathways in arthropods is lacking. In the present study, we report the cloning and expression of cyclooxygenase (COX) from amphipod crustaceans Gammarus spp and Caprella spp. The amphipod COX proteins contain key residues shown to be important for cyclooxygenase and peroxidase activities. Differently from all other known cyclooxygenases the N-terminal signal sequence of amphipod enzymes is not cleaved during protein expression in mammalian cells. The C-terminus of amphipod COX is shorter than that of mammalian isoforms and lacks the KDEL(STEL)-type endoplasmic reticulum retention/retrieval signal. Despite that, amphipod COX proteins are N-glycosylated and locate similarly to the vertebrate COX on the endoplasmic reticulum and nuclear envelope. Both amphipod COX mRNAs encode functional cyclooxygenases that catalyze the transformation of arachidonic acid into prostaglandins. Using bioinformatic analysis we identified a COX-like gene from the human body louse Pediculus humanus corporis genome that encodes a protein with about 30% sequence identity with human COX-1 and COX-2. Although the COX gene is known to be absent from genomes of Drosophila sp., Aedes aegypti, Bombyx mori, and other insects, our studies establish the existence of the COX gene in certain lineages within the insect world. | The ω-6 and ω-3 polyunsaturated fatty acids (PUFAs) such as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are the precursors of various bioactive lipid mediators including prostaglandins, thromboxanes, leukotrienes, hydroxyeicosatetraenoic acid, isoprostanes, lipoxins, and resolvins (Rvs). These lipid mediators play important roles in various physiological and pathological processes. The quantitative determination of PUFA metabolites seems necessary for disease research and for developing biomarkers. However, there is a paucity of analytical methods for the quantification of ω-6 and ω-3 PUFA metabolites—the specialized pro-resolving mediators (SPMs) present in the human urine. We developed a method for the quantification of ω-6 and ω-3 PUFA metabolites present in human urine using ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS). The developed method shows good linearity, with a correlation coefficient >0.99 for all of the analytes. The validation results indicate that our method is adequately reliable, accurate, and precise. The method was successfully used to examine urine samples obtained from 43 healthy volunteers. We could identify 20 PUFA metabolites, and this is the first report of the quantitative determination of RvD1, 17(R)-RvD1, 11-dehydro thromboxane B3, RvE2, and 5(S)-HETE in human urine. The urinary 8-iso PGF(2α) and PGE2 levels were significantly higher in the men smokers than in the men nonsmokers (p < 0.05). In this study, we developed an accurate, precise, and novel analytical method for estimating the ω-6 and ω-3 PUFA metabolites, and this is the first report that the SPMs derived from EPA and DHA are present in human urine. | eng_Latn | 27,274 |
This paper describes the reliable determination of progesterone (P4) in undiluted saliva making use of a disposable amperometric immunosensors implemented on low-cost and portable device/potentiostat constructed with commercial-off-the-shelf (COTS) components. The immunosensor allows the fast (45 min), selective and sensitive determination (5 pg mL−1 LOD) of P4 using amperometry in stirred solutions. The immunosensor was coupled to the COTS-based potentiostat and amperometry was made into drops of quiescent solutions. No significant differences were apparent between the analytical performance achieved with the immunosensor for P4 using both a conventional and the COST-based potentiostats. The practical applicability of the immunosensor coupled with the COTS-based potentiostat was demonstrated by determining the endogenous P4 content in different undiluted saliva samples with highly variable endogenous contents of the target hormone. The obtained results were in good agreement with those provided by the conventional ELISA methodology and with the contents reported in the literature for samples with similar characteristics. This validated the combined device for the reliable and minimally invasive determination of the target hormone involving a very simple protocol and taking only 45 min. | Antibiotics are an important class of drugs destined for treatment of bacterial diseases. Misuses and overuses of antibiotics observed over the last decade have led to global problems of bacterial resistance against antibiotics (ABR). One of the crucial actions taken towards limiting the spread of antibiotics and controlling this dangerous phenomenon is the sensitive and accurate determination of antibiotics residues in body fluids, food products, and animals, as well as monitoring their presence in the environment. Immunosensors, a group of biosensors, can be considered an attractive tool because of their simplicity, rapid action, low-cost analysis, and especially, the unique selectivity arising from harnessing the antigen–antibody interaction that is the basis of immunosensor functioning. Herein, we present the recent achievements in the field of electrochemical immunosensors designed to determination of antibiotics. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,275 |
Dioxin and dioxin-like activity in sediments of the North Sea, along the Belgian coast, was assessed with the bioassay CALUX (Chemically Activated LUciferase gene eXpression). Crude extracts of the samples as well as the dioxin fraction (PCDD/Fs) obtained after a thorough clean-up procedure were analyzed with the CALUX method. When analyzing the cleaned extract, a general low contamination level is observed (around 0.1 pg CALUX-TEQ/g sediment), except at the mouth of the two main rivers-the Yser and the Scheldt-where concentrations measured are about 100 times higher (10-42 pg CALUX-TEQ/g sediment). Much higher potencies are measured for the crude extracts compared to the cleaned ones. In the crude extracts, the highest dioxin-like activities were again observed at the mouth and outflow of the two rivers (600-7200 pg CALUX-TEQ/g sediment). These activities are at least two orders of magnitude higher than the ones found at the coastal and sea stations (1.3-45 pg CALUX-TEQ/g sediment). The difference in activity between cleaned and crude sediment extracts is due to the presence of dioxin-like compounds such as, for example, non-ortho and mono-ortho polychlorinated biphenyls and polybrominated dioxins, but also to PAHs. The percentage of five major PAHs in the crude samples at the river mouths, when using the average activities in those samples, varies between 25% and 50%. | Relative potency (REP) estimates are widely used to characterize and compare the potency of a wide variety of samples analyzed using in vitro bioassays. Relative potency estimates are generally calculated as a simple ratio: the EC50 of a well-characterized standard divided by the EC50 of a sample. Such estimates are valid only when the dose-response curves for the sample and standard are parallel and exhibit the same maximum achievable response (efficacy). These conditions are often either violated or cannot be demonstrated. As a result, there is a need to calculate and present REPs in a manner that addresses the potential uncertainties caused by violation of the assumptions of parallelism and equal efficacy. Multiple point estimates, over the range of responses from EC20 to EC80, can be used to derive relative potency ranges (REP 20 80 range). The width of a REP 20-80 range is directly proportional to the degree of deviation from parallelism between sample and standard dose-response curves. Thus, REP 20 80 ranges both test the assumption of parallelism and characterize the amount of uncertainty in an REP estimate resulting from deviation from parallelism. Although uncertainties due to unequal efficacy cannot be easily characterized mathematically, a systematic method for evaluating sample efficacy has been developed into a framework to guide the derivation and application of REP estimates based on in vitro bioassay results. Use of the systematic framework and REP 20 80 o ranges was illustrated using three sample data sets. It is hoped that the framework and discussion presented will facilitate the use of bioassay-derived REP estimates to characterize samples of both known and unknown composition without ignoring the assumptions underlying REP estimation. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,276 |
Different category-wastewater samples were collected from the inlets of biological treatment plants (installed in hospitals, industries and municipality) and from the body of polluted natural surface water (PNSW) systems (lakes, rivers). UV absorption spectral data of each wastewater system or their fractions as obtained by fractionation with membranes of various pore openings or with gel permeation chromatography were treated by supervised (neural network) and unsupervised (cluster analysis) pattern recognition methods with the target to classify them in clusters that include exclusively samples of the same category. The results based on neural network method applied to log10(UV-absorption spectra) of 80 wastewater samples gave a prediction score of around 77% for all category-samples. The cluster analysis method applied to the 1st derivative of log10(UV-absorption spectra) of 79 wastewater samples gave a promising classification for one of the four category wastewater samples and the others were grouped in sub-clusters of the same cluster without clear separation. Fractionation through membrane dialysis of two extremely non-similar UV-spectra samples from each category showed that the cluster analysis was more successful when UV-absorption spectra of the high molecular weight fractions were used in cluster analysis. Fractionation with GPC-chromatography gave chromatographic peaks and peak-spectra that are different for each category of wastewater samples; this method revealed that the MW of absorbing species are different and the absorption intensities are significantly different between the inlet feeds of the three types of wastewater treatment plants. | The performance of activated sludge reactors can be enhanced by the ability to monitor the status of the process without the need for chemicals addition or complex calibration procedures. Nowadays automation is still limited by poor sensor performance and high maintenance costs. Spectroscopic methods associated with chemometrics are being presented as a powerful tool for process monitoring and control. Once implemented, the method is fast, non-destructive and it can be implemented online, permitting to rapidly infer about the status of the process being monitored. In this work, UV-Visible and Near Infra-Red (NIR) Spectroscopy were used to monitor an activated sludge reactor using immersion probes that were connected to the respective spectrophotometers using optical fibbers. During the monitoring period, changes were induced in the system to test the ability of the monitoring scheme to detect them. The results obtained so far show that it is possible to clearly detect changes in the influent composition as well as the effects of a sudden increase in the influent flow which are among the most common problems that can disturb a biological WWT system. The use of the NIR range for this application is not as common as the UV-Visible range and a direct comparison will allow taking conclusions about the advantages and/or disadvantages of one compared to the other. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,277 |
A sensitive method, based on liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS), was developed for the determination of trimetazidine in human plasma. Buflomedil was used as the internal standard (IS). Plasma samples were extracted with a mixture of cyclohexane-diethyl ether (1:1, v/v) and the analytes were chromatographically separated on a phenomenex Luna 5 mu C18 (2) 100A HPLC column with a mobile phase of 10 mM ammonium acetate buffer solution containing 0.1% acetic acid-methanol (45:55, v/v). The electrospray ionization was employed in a single quadrupole mass spectrometer for the analytical determination. The lower limit of quantification (LLOQ) was 0.5 ng/ml for trimetazidine and the measuring ranges were from 0.5 to 200 ng/ml. The intra- and inter-run standard deviation was less than 4.1% and 7.8%, respectively. The method was successfully applied to study the pharmacokinetics of trimetazidine in healthy Chinese volunteers. | A simple RP-HPLC-PDA method for determination of atenolol (ATN) and trimetazidine (TMZ) in human urine and tablets has been developed. Analytes were separated on a Caltrex BI column (125× 4.0 mm, 5 μm) with 25mM potassium dihydrogen phosphate pH 3.3, methanol, and acetonitrile mobile phases. The PDA detector was operated at 210 nm for TMZ and 225 nm for ATN and the flow rate was 1.0 mL/ min. Linearity was obtained over a concentration range of (1.0-100 μg/mL) for both analytes in standard solutions and the method was successfully applied for determination of target analytes in their pharmaceutical tablets. Excellent linearity was also obtained over concentration ranges of (0.25-25 μg/mL) and (0.5-25 μg/mL) in human urine for TMZ and ATN, respectively. A simple liquid-liquid extraction was applied for urine sample clean-up and a gradient method was used for chromatographic separation. The lower limit of quantitation (LOQ) was 0.99 and 0.60 μg/mL for ATN and TMZ, respectively. The limit of detection (LOD) was 0.30 and 0.18 μg/mL for ATN and TMZ, respectively. Inter- and intraday precision and accuracy for ATN were within ±1.89% in pure form and within ±2.85% in urine samples. Inter- and intraday precision and accuracy for TMZ were within ± 3.99% in pure form and within ± 3.19% in urine samples. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,278 |
In vitro influence of five synthesized functionalized hexavanadates (V 6 ) on commercial porcine cerebral cortex Na + /K + -ATPase activity has been studied. Dose dependent Na + /K + -ATPase inhibition was obtained for all investigated compounds. Calculated half maximal inhibitory concentration IC 50 values, in mol/L, for Na + /K + -ATPase were 7.6 × 10 − 5 , 1.8 × 10 − 5 , 2.9 × 10 − 5 , 5.5 × 10 − 5 for functionalized hexavanadates (V 6 ) with tetrabutylammonium (TBA) [V 6 –CH 3 ][TBA] 2, [V 6 –NO 2 ][TBA] 2 , [V 6 –OH][TBA] 2 and [V 6 –C 3 ][TBA] 2 respectively. [V 6 –OH][Na] 2 inhibited Na + /K + -ATPase activity up to 30% at maximal investigated concentration 1 × 10 − 3 mol/L. This reactivity has been interpreted using a study of the non-covalent interactions of functionalized hexavanadate hybrids through Cambridge Structural Database (CSD) analysis. Bibliographic searching has led to 18 different structures and 99 contacts. We have observed that C–H ⋯ O contacts consolidate the structures. We have also performed density functional theory (DFT) calculations and have determined electrostatic potential values at the molecular surface on a series of functionalized V 6 . These results enlightened their chemical reactivity and their potential biological applications such as the inhibition of the ATPase. | Tetravalent (VIV) and pentavalent (VV) forms of vanadium were selected for testing by the National Toxicology Program via drinking water exposure due to potential human exposure. To aid in the test article selection, drinking water formulations (125–2000 mg/L) of vanadyl sulfate (VIV), sodium orthovanadate, and sodium metavanadate (VV) were characterized by ultraviolet/visible (UV/VIS) spectroscopy, mass spectrometry (MS), or 51V nuclear magnetic resonance (NMR) spectroscopy. Aqueous formulations of orthovanadate, metavanadate, and vanadyl sulfate in general were basic, neutral, and acidic, respectively. Changes in vanadium speciation were investigated by adjusting formulation pH to acidic, neutral, or basic. There was no visible difference in UV/VIS spectra of pentavalent forms. NMR and MS analyses showed that the predominant oxidovanadate species in both ortho- and metavanadate formulations at basic and acidic pH, respectively, were the monomer and decamer, while, a mixture of oxidovanadates were present at neutral pH. Oxidovanadate species were not observed in vanadyl sulfate formulations at acidic pH but were observed at basic pH suggesting conversion of VIV to VV. These data suggest that formulations of both ortho- and metavanadate form similar oxidovanadate species in acidic, neutral and basic pH and exist mainly in the VV form while vanadyl sulfate exists mainly as VIV in acidic pH. Therefore, the formulation stability overtime was investigated only for sodium metavanadate and vanadyl sulfate. Drinking water formulations (50 and 2000 mg/L) of metavanadate (~pH 7) and vanadyl sulfate (~pH 3.5) were ≥92 % of target concentration up to 42 days at ~5 °C and ambient temperature demonstrating the utility in toxicology studies. | Activity of liver ornithine transcarbamylase was measured in a biopsy obtained from a seven years old girl, suffering from chronic hyperammonemia and orotic aciduria. The activity of the defective enzyme was only 17% of that of a control. pH optimum was 8.1 in the patient and the control. However, the pH curves were different between 7.0 and 8.1. Km (ornithine) of the patient's ornithine transcarbamylase was within the normal range (0.41 nM), but the Km (carbamyl phosphate) was low (0.18 mM). The girl seems to be a heterozygote carrier of ornithine transcarbamylase deficiency due to an abnormal liver enzyme. | eng_Latn | 27,279 |
Results of an interlaboratory study are reported for the determination of lead in urine. Two levels of a lyophilized material containing biologically-bound lead were prepared using pooled urine obtained from lead-poisoned children undergoing the CaNa 2 EDTA mobilization test. The materials were circulated to a group of reference laboratories that participate in the `New York State Proficiency Testing Program for Blood Lead'. Results of the initial round-robin gave all-method consensus target values of 145±22 μg/l (S.D.) for lot 17 and 449±43 μg/l (S.D.) for lot 20. The interlaboratory exercise was repeated some 5 years later and consensus target values were re-calculated using the grand mean (excluding outliers) of results reported by laboratories using electrothermal atomization atomic absorption spectrometry (ETAAS). The re-calculated target values were 139±10 μg/l (S.D.) and 433±12 μg/l (S.D.). The urine reference materials were also analyzed for lead by several laboratories using other instrumental techniques including isotope dilution (ID), inductively coupled plasma (ICP) mass spectrometry (MS), flame atomic absorption with extraction, ICP-atomic emission spectrometry, ID-gas chromatography MS and flow injection-hydride generation AAS, thus providing a rich source of analytical data with which to characterize them. The materials were also used in a long-term validation study of an ETAAS method developed originally for blood lead determinations that has since been used unmodified for the determination of lead in urine also. Recently, urine lead method performance has been tracked in a proficiency testing program specifically for this analysis. In addition, a number of commercial control materials have been analyzed and evaluated. | Objective: We sought to compare associations of patella lead, which may represent a unique cumulative and bioavailable lead pool, with other lead measures in models of renal function. Methods: Renal function measures included blood urea nitrogen, serum creatinine, measured and calculated creatinine clearances, and urinary N-acetyl-β-D-glucosaminidase (NAG) and retinol-binding protein. Results: In 652 lead workers, mean (SD) blood, patella, and tibia lead were 30.9 (16.7) μg/dL, 75.1 (101.1) and 33.6 (43.4) μg Pb/g bone mineral, respectively, and were correlated (Spearman's r = 0.51-0.74). Patella lead was associated (P < 0.05) with NAG in all lead workers. In models of elect modification by age, higher patella lead also was associated with higher serum creatinine in older participants. Similar associations were observed for blood and tibia lead. Conclusions: Associations between patella lead and adverse renal outcomes were not unique; this may be due, in part, to high correlations among the lead biomarkers in this study. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 27,280 |
The effect of nicotine, and some nicotinic antagonists on aggressive behavior of isolated mice was tested. Nicotine in doses of 0.5-2 mg/kg ip and 0.005-0.06 mg/mouse ivtr potentiated the aggressiveness. However, higher doses nicotine (4 mg/kg ip and 0.09 mg/kg (Polfa). Co-suppressed the aggression. Mecamylamine, a central nicotinic antagonist in a dose of 2 mg/kg facilitated the aggression while in doses of 4 and 8 mg/kg inhibited it. Hexamethonium, a peripheral nicotinic antagonist, partially suppressed the aggressive behavior. Our results indicate that central nicotinic receptors have also a certain role in mediating the investigated type of mouse aggression. | Nicotine is reported to have toxic effects on gonadal functions, in addition to its established role in the pathogenesis of atherosclerosis and lung cancer. So nicotine-induced biochemical changes were studied in liver and testes. Chronic administration of nicotine was found to produce enhanced synthesis of cholesterol, triglycerides, phospholipids and free fatty acids in the liver and testes. The activity of the lipogenic enzymes was high in liver but unaltered in testes. The testosterone and estradiol levels in the serum were lower. As the changes brought about by chronic administration of nicotine were counteracted by mecamylamine, a known inhibitor of nicotine, it was proven that nicotine is having a specific gonadotoxic effect. | Polyacrylamide (PAM) treatment of irrigation water is a growing conservation technology in irrigated agriculture in recent years. There is a concern regarding the environmental impact of PAM after its application. The effects of anionic PAM on the sorption characteristics of four widely used herbicides (metolachlor, atrazine, 2,4-D, and picloram) on two natural soils were assessed in batch equilibrium experiments. Results showed that PAM treatment kinetically reduced the sorption rate of all herbicides, possibly due to the slower diffusion of herbicide molecules into interior sorption sites of soil particles that were covered and/or cemented together by PAM. The equilibrium sorption and desorption amounts of nonionic herbicides (metolachlor and atrazing) were essentially unaffected by anionic PAM, even under a high PAM application rate, while the sorption amounts of anionic herbicides (2,4-D and picloram) were slightly decreased and their desorption amounts increased little. The impact mechanisms of PAM were related to the molecular characteristics of PAM and herbicides. The negative effects of PAM on the sorption of anionic herbicides are possibly caused by the enhancement of electrostatic repulsion by presorbed anionic PAM and competition for sorption sites. However, steric hindrance of the large PAM molecule weakens its influence on herbicide sorption on interior sorption sites of soil particles, which probably leads to the small interference on herbicide sorption, even under high application rates. | eng_Latn | 27,281 |
Micellar structures of cationic alkyltrimethylammonium bromide (CnTAB) surfactants for different chain lengths (n = 12, 14 and 16) in aqueous solution on the addition of two oils benzene and hexane have been studied by small‐angle neutron scattering (SANS). Measurements have been performed for fixed 0.1 M concentration of surfactant and oil. It is found that the size and the aggregation number of the micelles increase on oil solubilization with increase in oil concentration. The effect is more pronounced for larger size of the micelles having longer chain length and also for the oil benzene than hexane. The axial ratio of the micelles shows a large increase and the effective charge on the micelles decreases on addition of oil. There is only a small increase in semiminor axis on addition of oil, which suggests that distribution of oil is uniform inside the micellar core. | Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions ::: have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2- ::: 10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30- ::: 50 A has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and ::: short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a sphericallike ::: structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol, octanol and decanol was ::: added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then ::: crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by ::: further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and ::: concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of nalcohol, ::: pentanol at all concentrations. ::: Keywords: small-angle neutron scattering, micellar solution, micelles, liquid crystals, lamellar structure. ::: PACS: 61.05.fg; 61.30.-v; 64.70.M-; 64.70.pv. | The purpose of the present investigation was to follow and correlate changes of structural and biochemical markers of energy metabolism during chronic electrical stimulation of tibialis anterior muscle in rabbits. In the superficial portion of the muscle, 5 to 6-fold increases occurred in enzyme activities of the citric acid cycle and of fatty acid oxidation after 28 days of stimulation. Enzyme activity changes in the deep, more oxidative part of the muscle were relatively smaller. Consequently, levels of the citric acid cycle enzymes became similar in superficial and deep parts of the muscle after the longest stimulation periods. With the exception of hexokinase, which increased in parallel with the citric acid cycle enzymes, glycolytic enzymes decreased 2 to 3-fold. Muscle mass and fibre size remained unchanged, while capillary density and capillary to fiber ratio increased 2-fold. The volume density of total mitochondria increased in a fashion similar to the changes of the enzymes of the citric acid cycle (7-fold in superficial and 3.5-fold in deep parts of the muscle) and, thus, approached values found in heart muscle. Disproportionate changes in enzyme activities of ketone body utilisation and of mitochondrial glycerolphosphate oxidase indicated qualitative changes within the mitochondrial population. However, the proportion of subsarcolemmal to interfibrillar mitochondria, as well as the area of inner mitochondrial membrane per unit volume of mitochondrion remained unchanged. Similarly, intracellular lipid deposits remained unchanged with stimulation. It is concluded that there is an excellent agreement between morphometric and biochemical measurements of tissue oxidative capacity. | eng_Latn | 27,282 |
This paper, for the first time, reported a speedy hyphenated technique of low toxic dual ultrasonic-assisted dispersive liquid–liquid microextraction (dual-UADLLME) coupled with microwave-assisted derivatization (MAD) for the simultaneous determination of 20( S )-protopanaxadiol (PPD) and 20( S )-protopanaxatriol (PPT). The developed method was based on ultra high performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) detection using multiple-reaction monitoring (MRM) mode. A mass spectrometry sensitizing reagent, 4′-carboxy-substituted rosamine (CSR) with high reaction activity and ionization efficiency was synthesized and firstly used as derivatization reagent. Parameters of dual-UADLLME, MAD and UHPLC-MS/MS conditions were all optimized in detail. Low toxic brominated solvents were used as extractant instead of traditional chlorinated solvents. Satisfactory linearity, recovery, repeatability, accuracy and precision, absence of matrix effect and extremely low limits of detection (LODs, 0.010 and 0.015 ng/mL for PPD and PPT, respectively) were achieved. The main advantages were rapid, sensitive and environmentally friendly, and exhibited high selectivity, accuracy and good matrix effect results. The proposed method was successfully applied to pharmacokinetics of PPD and PPT in rat plasma. | In this work, we have developed an efficient method for the rapid extraction and separation of triterpene acids from 37 different varieties of raspberry via ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME). The triterpene acids were then determined by high-performance liquid chromatography (HPLC) with fluorescence detection using benzimidazo-[2,1-b]quinazolin-12(6H)-one-5-ethyl-p-toluenesulfonate (BQETS) as the labeling agent. Five triterpene acids, including asiatic acid (AA), maslinic acid (MA), corosolic acid (CA), oleanolic acid (OA) and betulinic acid (BA), were extracted by UA-DLLME using chloroform and acetone as the extracting and dispersing solvents, respectively. After extraction and nitrogen flushing, the extracts were simultaneously characterized by HPLC based on pre-column derivatization using BQETS, a new labeling agent synthesized in our laboratory. Several key parameters affecting the extraction efficiency and derivatization yields were investigated and optimized by response surface methodology (RSM) combined with Box–Behnken design (BBD). The method was further validated for linearity (correlation coefficient R 2 > 0.9979), precision (RSD = 0.23–2.45 %), and recovery (RSD = 90–106.5 %). The limits of detection (LODs) and the limits of quantification (LOQs) were determined to be within the range of 1.83–7.69 µg/L and 6.06–25.47 µg/L, respectively. This is the first report of the use of BQETS as a pre-column derivatization agent for the determination of triterpene acids in real samples. The proposed method has been applied to the determination of five triterpene acids in 37 different raspberry varieties with significantly increased sensitivity compared to other methods. The results obtained indicate that the contents of triterpene acids vary significantly across different raspberry varieties. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,283 |
A sensitive direct colourimetric method has been employed to measure kinetic parameters and pH dependence of carbamyl phosphate synthetase-I, in a liver sample from a 2 1/2-month-old girl, who died from complications of a late-developing congenital hyperammonaemia. The residual activity of carbamyl phosphate synthetase-I was 25%, whereas other urea cycle enzymes were within normal range. Apparent Km for ammonium ion (0.73 mmol/L) was significantly increased (normal range 0.24-0.51). Km for bicarbonate ion was normal, while Km for NAG showed a slight variation from normal. The pH dependence curve of the patient's enzyme was flat, as compared to two controls showing pH optima at 7.8. Radial immunodiffusion (Mancini) of the abnormal enzyme against human enzyme antiserum gave a cross-reacting material of 10-20%. The methodological approach presented can be used to characterize abnormal enzymes in cases of partial deficiency with only 100-200 mg of liver tissue. | Activity of liver ornithine transcarbamylase was measured in a biopsy obtained from a seven years old girl, suffering from chronic hyperammonemia and orotic aciduria. The activity of the defective enzyme was only 17% of that of a control. pH optimum was 8.1 in the patient and the control. However, the pH curves were different between 7.0 and 8.1. Km (ornithine) of the patient's ornithine transcarbamylase was within the normal range (0.41 nM), but the Km (carbamyl phosphate) was low (0.18 mM). The girl seems to be a heterozygote carrier of ornithine transcarbamylase deficiency due to an abnormal liver enzyme. | A glutamine-dependent carbamyl phosphate synthetase, the occurrence of which was suggested by previous studies with intact cells, has been found in extracts of Ehrlich ascites carcinoma. The activity is detectable by measuring the incorporation of 14C-bicarbonate of high specific activity into citrulline when purified Streptococcus faecalis ornithine transcarbamylase and ornithine are added to the extract. The 14C-bicarbonate incorporation into citrulline requires (in addition to the tumor extract, ornithine transcarbamylase, and ornithine) magnesium, adenosine triphosphate, and glutamine or ammonia. The Km for glutamine is close to 10-5 m, whereas the Km for ammonium chloride is about 5 x 10-3 m. The incorporation is inhibited by glutamine analogues when either glutamine or ammonia is the substrate. A standard assay and a procedure to stabilize the enzyme are described. Other properties of the extracted enzyme are described. The enzyme is similar to the glutamine-dependent carbamyl phosphate synthetases from mushroom, Escherichia coli and yeast. The role of this enzyme in mammalian and avian pyrimidine synthesis is discussed. | eng_Latn | 27,284 |
In this work, we reported an advanced enzyme-assisted etching method using gold nanorods (AuNRs) as signal output of plasmonic enzyme-linked immunosorbent assay (pELISA) for the quantitative or qualitative detection of aflatoxin B 1 (AFB 1 ) in real corn samples. AFB 1 -labeled glucose oxidase was adopted as the competing antigen to catalyze glucose into H 2 O 2 . Meanwhile, horseradish peroxidase was employed to catalyze H 2 O 2 and hence generate . OH. The AuNRs with the aspect ratio of 2:1 were chemically etched by OH to a rod-like morphology. This occurrence reduced the optical density at 650 nm and resulted in a vivid color response from bluish-green to red easily detectable by a microplate reader for quantitative AFB 1 analysis or by the naked eye for qualitative AFB 1 detection. Various parameters that may influence the detection performance of pELISA were investigated. The proposed method showed an extremely high sensitivity for qualitative AFB 1 detection, with a visible cut-off value of 12.5 pg/mL. The technique also achieved a good linear range of 3.1–150 pg/mL for quantitative AFB 1 analysis, with a half-maximal inhibitory concentration of 22.3 pg/mL, which was approximately 32 folds lower than those of conventional ELISA (707 pg/mL). The average recoveries for corn samples spiked with different concentrations of AFB 1 ranged from 82% to 115%, with a coefficient of variation that ranged from 2% to 13%. These values corresponded to an acceptable accuracy and precision for the proposed method. In addition, the reliability of the proposed method was further confirmed by the liquid chromatography–tandem mass spectrometry (LC–MS/MS) method. In brief, this work offers an improved screening strategy with high sensitivity and robustness for the qualitative or quantitative detection of mycotoxins or other pollutants in food safety monitoring. | A solid-phase extraction method was developed by using new bifunctional ionic liquid-based silicas as sorbents to isolate aflatoxin B1 from moldy corn and peanut. Firstly, according to the adsorption efficiency, two sorbents imidazolium chloride-butylimidazolium chloride-based silica (Sil@BIm-Im) and imidazolium chloride-hexylimidazolium chloride-based silica (Sil@HIm-Im) were selected. The RSM was introduced to optimize adsorption conditions such as methanol/water ratio, time, and pH. Sil@HIm-Im, which had the highest adsorption efficiency, was used in SPE as a sorbent. After 2.0 mL of loading samples, washing solvents were optimized as 6.0 mL and 4.0 mL of water for corn and peanut, 2.0 mL of acetonitrile, and 3.0 mL of methanol. 3.0 mL of methanol/acetic acid (2.0% vol.) was investigated as an elution solvent. Finally, 0.009 μg/g and 0.023 μg/g of aflatoxin B1 were obtained in corn and peanut extract with recoveries of 80.0%–103.3% and RSDs of 2.37%–6.58%. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,285 |
Diseased skin of dogs was stained using the critical electrolyte concentration-Alcian Blue method, PAS methods, and the high iron diamine technique. Digestion with testicular hyaluronidase and chondroitinase was also used to evaluate the staining results. | A. G. E. Pearse is a relative newcomer to the field of histochemistry. He holds an M.D. degree from the University of Cambridge and is now Lecturer in Histochemistry at the Postgraduate Medical School, University of London. One of his first contributions to histochemistry consisted of a critical review of its methodology and interpretation, written for pathologists and appearing in the British Journal of Clinical Pathology 4: 1 (1951). He has also introduced a number of new or modified techniques. Perhaps those having the greatest interest for endocrinologists are presented in a series of papers concerning the demonstration of the glycoprotein hormones of the anterior pituitary gland (Nature 162: 651, 1948; J. Path. & Bad. 61: 195, 1949, 64: 791 & 811, 1952; Stain Technol. 25: 95, 1950). The present volume comprises 17 chapters, beginning with a brief but fairly inclusive history of the development of this branch of science and continuing with 2 chapters on methods of fixation and sectioning, 3 on the staining of proteins, 4 on the demonstration of enzymes, 1 on the use of enzymes as histochemical reagents, and 1 each on carbohydrates, lipids, aldehydes and ketones, pigments, inorganic substances, and physical methods. The book concludes with appendices which give the detailed steps of the histochemical techniques which Dr. Pearse has himself found most useful for demonstrating various tissue constituents. Complete author and subject indices follow. A further valuable feature of the book consists of numerous black-and-white and a few colored photomicrographs illustrating the appearance of sections prepared by some of the histochemical methods discussed. A rash of books devoted entirely or largely to histochemical techniques has appeared in the last few years. Outstanding are the treatises by Lillie (1948), Romeis (1948, 15th ed., German), Glick (1949), Gatenby and Beams (1950, 11th ed.), Gomori (1952), and Lison (1953, 2nd ed., French). In this reviewer's opinion, the new Pearse bids fair to become the leader, even amongst so notable a collection. In each chapter, Dr. Pearse reviews the chemistry and biological importance of the substances in question and then goes on to discuss critically the methods used for their demonstration and differentiation. The bibliographic references are numerous and appear to include most of the major contributions in each area. Pearse has omitted some references which appear fundamental, for example, the definitive experimental paper and review by Marcus Singer concerning the nature of acidic and basic staining of proteins (/. Biol. Chem. 75: 133, 1948; Internal. Rev. Cytol. I: 211, 1952). Likewise, the techniques which he has selected to give in detail represent his particular preferences, whereas numerous methods which are possibly equally satisfactory are barely mentioned. While Pearse's omissions in this respect are not serious, the usefulness of some methods which he has overlooked should not be lost sight of. Needless to say, in a field which is growing so rapidly and to which several journals are now entirely devoted, no book can long remain up-to-date. | Silane surface technology have been rapidly developed in the field of anti-corrosion of metals as one of the “green” replacements for conventional chromizing. The article introduced the corrosion prevention mechanism of silane treatment; factors affecting performance of the silane film(including silane categories, the concentration and pH of the silane solution, and deposition methods); modified technologies(such as loading nanoparticles, doping corrosion inhibitor and adding suitable dyes and colorants); analytical and characterization techniques of the silanizing film. The shortage that existed currently in silane treatment is also discussed. All above are aimed to promote the research of environmental friendly surface passivation technology on aluminum alloy. | eng_Latn | 27,286 |
Nucleation-growth models for the kinetic analysis of gas–solid reactions in which nucleation proceeds at the surface of the particles are reported. The growth of the nuclei is assumed to be anisotropic, i.e. with a very fast surface rate compared to the bulk one. The nucleation and growth processes are assumed to occur with, respectively, an areic frequency γ (nb. nuclei m−2 s−1) and an areic reactivity ϕ (mol m−2 s−1), both depending only on the thermodynamic variables (such as temperature, partial pressures …) established during the reaction. Depending on the shape of the particles, the direction of growth and the localization of the rate-determining step, eighteen analytical expressions of kinetic rate are obtained. The importance of particle size is also put in evidence. | Bayesian methods are growing ever more popular in chemical kinetics. The reasons for this and general challenges related to kinetic parameter estimation are shortly reviewed. Most authors content themselves with using one single (mostly uniform) prior distribution. The goal of this paper is to go into some serious issues this raises. The problems of confusing knowledge and ignorance and of reparametrisation are examined. The legitimacy of a probabilistic Ockham’s razor is called into question. A synthetic example involving two reaction models was used to illustrate how merging the parameter space volume with the model accuracy into a single number might be unwise. Robust Bayesian analysis appears to be a simple and ::: straightforward way to avoid the problems mentioned throughout this article. | A method is described for the isolation and growth in vitro of fully differentiated neurones from the thoracic ganglia of adult cockroaches. The presence of insect blood in the culture system is shown to promote growth. The morphology of the growing neurones and the plasticity of the branching processes are described and growth rates are measured. Using a fluorescent Ca2+ indicator dye, changes of intracellular calcium levels in the growing neurones in response to K+ depolarization have been measured. The results, indicating the presence of voltage-dependent Ca2+ channels on neuronal processes in vitro, show that neurones can be maintained in a functional state for several weeks by this technique. Such preparations could prove useful for studying a variety of physiological and pharmacological properties of neurones, including the mechanisms controlling growth, synapse formation and neuronal interactions with other cell types. | eng_Latn | 27,287 |
Determination of the content of vitamin D is a rather difficult problem. In the present study, we have compared methods that are most widely used for determining group D vitains. In recent years, physical and chemical methods of analysis have found increasing use due to their simplicity, sensitivity, and information value. Various methods of quality control are currently used but the future in the analysis of calciferols undoubtedly belongs to HPLC. This method is capable of simultaneously solving all problems encountered in the analysis of group D vitamins. | The idea of using a chromatographic adsorbent in the form of a thin layer fixed on an inert rigid support seems to have been suggested by Izmailov and Shraiber in 1938. Meinhard and Hall[1] in 1949 developed this notion of an ‘open column’, and in 1951 Kirchner, Miller, and Keller[2] reported the separation of terpenes on a ‘chromatostrip’, prepared by coating a small glass strip with an adsorbent mixed with starch or plaster of Paris, which acted as a binder. The strips were handled in the same way that paper is handled in paper chromatography, and indeed the original object of the thin-layer technique was to apply the methods of paper partition chromatography to an adsorption system. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,288 |
The present study was aimed to develop a highly specific and sensitive Enzyme Linked Immunosorbent Assay (ELISA) to measure progesterone in human serum using a heterologous combination of immunogen and enzyme conjugate. The antiserum was raised against Progesterone-3-O-carboxymethyloxime bovine serum albumin (P-3-O-CMO-BSA) in New Zealand white rabbits. The enzyme conjugate was prepared by labeling 17-alpha-hydroxy-progesterone-3-O-carboxymethyloxime (17-alpha-OH-P-3-O-CMO) with Horseradish Peroxidase (HRP) to form 17-alpha-OH-P-3-CMO-HRP. A Checkerboard assay was performed to determine the working dilutions of antiserum and enzyme conjugate. Dose-response studies were carried out by incubating 100microL enzyme conjugate along with 50microL of standards in the primary antibody coated wells for 1 hour. The bound enzyme activity was measured colorimetrically using tetramethyl benzidine/hydrogen peroxide (TMB/H(2)O(2)) as substrate. The enzyme substrate reaction was terminated with 100microL of 0.5 M H(2)SO(4) after 20 min and the intensity of the color was measured using Tecan ELISA reader at 450 nm. The assay was validated in terms of sensitivity, specificity, precision and recovery. The lowest detection limit of the assay was 0.2 ng/mL. Cross-reaction with analogous steroids pregnenolone and 17-alpha-OH-P were found to be 6.8 and 6.1%, respectively. For other analogous steroids, it was less than 0.1%. The intra- and inter-assay coefficient of variation ranges from 4.52-7.39% and 4.65-9.55%, respectively. The developed ELISA correlated well with established RIA, with a correlation coefficient of 0.91 (n = 40). | Purpose ::: Corticosteroids are effective in the management of a variety of disease states, such as several forms of neoplasia (leukemia and lymphoma), autoimmune conditions, and severe inflammatory responses. Molecular strategies that selectively “target” delivery of corticosteroids minimize or prevents large amounts of the pharmaceutical moiety from passively diffusing into normal healthy cell populations residing within tissues and organ systems. | We report nearly complete preservation of “spin memory” between optical absorption and photoluminescence under excitation >0.2 eV above the band gap in nanometer GaSe slabs. | eng_Latn | 27,289 |
The pharmacokinetics of antipyrine (phenazone) in 3 species of non-human primate have been evaluated following its intravenous administration at a dose level of 92 mg/kg. ::: ::: Mean peak plasma concentrations of antipyrine of 132, 137 and 155 μg/ ml in the rhesus monkey, the cynomolgus monkey and the baboon respectively were not observed until 5 min after intravenous injection. Thereafter, concentrations declined with an apparent half-life of elimination of 1.5–2 h. The time-course of plasma antipyrine concentrations was adequately described by a one-compartment open model and no notable differences in pharmacokinetic parameters utilising a 2-compartment open model were observed. ::: ::: Antipyrine was mainly distributed in total body water. The mean volume of distribution was equivalent to 88, 73 and 66% of body weight in the rhesus monkey, the cynomolgus monkey and the baboon, respectively. ::: ::: An analysis of variance of volumes of distribution, apparent half-lives of elimination and systemic clearances showed that there was a statistically significant species-related difference in systemic clearance (P < 0.05) and volumes of distribution (P < 0.01) which were lower in the cynomolgus monkey than in the other 2 species. ::: ::: The pharmacokinetics of antipyrine in the non-human primate are more similar to those of other laboratory animal species than to those of humans. | Purpose. A series of studies was conducted to evaluate the preclinical pharmacokinetics of SB-239063 (trans-1-(4-hydroxycyclohexyl) -4- (4-fluorophenyl) -5- [(2-methoxy) pyrimidin-4-yl] imidazole), a potent and selective p38 MAP kinase inhibitor. ::: Methods. SB-239063 was administered both i.v. and p.o. in the rat, dog, cynomolgus monkey, and rhesus monkey, with standard pharmacokinetic parameters generated from the concentration vs. time data. ::: Results. Initial rat studies suggested possible nonlinear disposition; however, assay refinement revealed an in vivo trans-cis isomerization of SB-239063 to a metabolite with nearly identical chromatographic and mass spectral properties. SB-239063 exhibited low to moderate clearance and good bioavailability in the rat and dog, but poor bioavailability in the cynomolgus monkey. Substantial in vivo trans-cis isomerization occurred in the rat and cynomolgus monkey, but occurred to a far lesser extent in the dog. The isomerization reaction was reversible, with a recycled fraction of 0.20 and 0.0003 in the rat and cynomolgus monkey, respectively. In the rhesus monkey, bioavailability was also poor, but no in vivo isomerization was observed. ::: Conclusions. These studies demonstrate the necessity of exercising vigilance in conducting high-throughput analytical method development, and the importance of using a variety of preclinical species when evaluating the disposition of new drug candidates. | N-substituted crosslinking polybenzimidazole pyridine sulfone, as novel high performance functional polymers, was prepared by the coordination of N-substituted polybenzimidazole pyridine sulfone (Py-N-PBIS) ligand with varying content of metallic ion (Co2+, Ni2+, Zn2+). The structures of the polymers were characterized by means of FT-IR and 1H NMR spectroscopy, and the results showed a good agreement with the proposed structures. TGA measurements exhibited that the crosslinking polymers possessed good thermal stability with high thermal decomposition temperatures (thermally stable up to 405-510 °C). Additionally, the thermal stability of the coordination polymers was improved constantly with the increasing of the content of Co2+, Ni2+ or Zn2+. The metal coordination crosslinking N-substituted polybenzimidazole pyridine sulfone could be considered as a novel high performance thermoset. | eng_Latn | 27,290 |
9 alpha ,15 alpha -Dihydroxy-11 alpha ,12 alpha -difluoromethylene-prosta-13-trans-enoic acid and 5-cis-13-transdienoic acid, 9-keto-11 alpha ,12 alpha -difluoromethylene-15 alpha -hydroxyprosta-13-trans-enoic acid and 5-cis-13-trans-dienoic acid, the 11 beta ,12 beta -difluoromethylene-12-epi compounds, as well as the pharmaceutically acceptable, non-toxic esters and salts thereof, process for the production of same and intermediates obtained by this process. These compounds possess prostaglandin-like activity and thus are useful in the treatment of mammals, where prostaglandins are indicated. | The NSDL metadata registry is designed to provide humans and machines with the means to discover, create, access and manage metadata schemes, schemas, application profiles, crosswalks and concept mappings. This paper describes the general goals and architecture of the NSDL Metadata Registry as well as issues encountered during the first year of the project's implementation. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 27,291 |
It is shown that Polaroid film may be used in place of X-ray film in many experiments employing radioautographic techniques. In 14 C experiments, the sensitivity of PolaPan Type 57 film is at least comparable to that of X-ray film, while radioactive iodine results in a slight increase in sensitivity of the Polaroid film over X-ray film. Darkroom facilities and time-consuming developing procedures are not necessary when Polaroid film is used. The background exposure usually acquired by X-ray film is nonexistent with Polaroid film. Under certain circumstances the differentiation of isotopes is possible in double-isotope experiments. | This study has explored the nature of the molecular events which occur when C1 inactivator, a human plasma inhibitor of the complement, kinin-forming, coagulation, and fibrinolytic enzyme systems, interacts with C1s, plasmin, and trypsin. Purified inhibitor preparations demonstrated two bands, when examined by acrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS). The molecular weights of the major and minor bands were 105,000 and 96,000 daltons, respectively. The minor component appeared to be immunologically and functionally identical to the main C1 inactivator component. Loss of C1s and plasmin functional activity was associated with the formation of a 1:1 molar complex between the inhibitor and each enzyme. These complexes were stable in the presence of SDS and urea. The light chain of both these enzymes provided the binding site for C1 inactivator. Complex formation and enzyme inhibition occurred only with native and not with an inhibitor preparation denatured by acid treatment, thereby demonstrating the importance of conformational factors in the enzyme-inhibitor reaction. Although peptide bond cleavage of the C1 inactivator molecule by C1s was not documented, plasmin was found to degrade the inhibitor with the production of several characteristic derivatives. At least one of these products retained the ability to complex with C1s and plasmin. Trypsin, which failed to form a complex with C1 inactivator, degraded the inhibitor in a limited and sequential manner with the production of nonfunctional derivatives one of which appeared structurally similar to a plasmin-induced product. These studies therefore, provide new information concerning the molecular interactions between C1 inactivator and several of the proteases which it inhibits. | The effect of water exposure on amorphous indium-gallium-zinc oxide (a-IGZO) semiconductors was reported. It was found that water can diffuse in and out of the a-IGZO film, reversibly affecting the transistor properties. Two competing mechanisms depending on the thickness of the active channel were clarified. The electron donation effect caused by water adsorption dominated for the thicker a-IGZO films (⩾100nm), which was manifested in the large negative shift (>14V) of the threshold voltage. However, in the case of the thinner a-IGZO films (⩽70nm), the dominance of the water-induced acceptorlike trap behavior was observed. The direct evidence for this behavior was that the subthreshold swing was greatly deteriorated from 0.18V/decade (before water exposure) to 4.4V/decade (after water exposure) for the thinnest a-IGZO films (30nm). These results can be well explained by the screening effect of the intrinsic bulk traps of the a-IGZO semiconductor. | eng_Latn | 27,292 |
Poly(2-aminoadenylic acid) forms both double and triple helices with poly(uridylic acid) [poly(U)]. The 2-amino group forms a third hydrogen bond, elevating the 2 leads to 1 transition temperature by 33 degrees C. The third strand, however, has about the same stability as poly(A)-2poly(U), as measured by Tm 3 leads to 2. This selective stabilization of the two-stranded helix results in a much greater resolution of the differnt thermal transitions than that observed in analogous polynucleotide systems. In contrast to other A, U systems 3 leads to 1 and 2 leads to 3 transitions are not observed under any conditions, and the triple helix always undergoes a 3 leads to 2 transition even at very high ionic strength. A 1:1 mixture of poly(2NH2A) and poly(U) exhibits no transient formation of 1:2 complex, unlike similar mixtures of poly(A) with poly(U) and poly(T). This difference is evidently due to a more rapid displacement reaction: [poly(2NH2A) + poly(2NH2A)-2poly(U) leads to 2 poly(2NH2A)-poly(U)] With poly(2NH2A) than with poly(A). We describe a method for establishing the combining ratios of polynucleotide complexes which used a computer to calculate the angles of intersection of mixing curves as explicit and continuous functions of the wavelength. The wavelength dispersions of the angles of intersection determine optimum wavelengths for establishing stoichiometry and can also provide reliable negative evidence that presumably plausible complexes are not formed. Analogous computer procedures have been developed to determine wavelengths which are selective for the formation of both 1:1 and 1:2 complexes. Infrared spectra of the 1:1 and 1:2 complexes resemble those of other A, U homoribopolynucleotide helices in having two and three strong bands, respectively, in the region of carbonyl stretching vibrations. CD spectra of the two complexes are unusual in having negative first extrema of moderate intensity. We attribute these extrema to intrastrand interactions of strong, well-resolved transitions at 278 nm (B2u) of the 2-aminoadenine residues. The CD spectra are correlated with those of other polynucleotide helices. | A random copolymer, poly(CA), containing approximately equal amounts of cytidine (C) and adenosine (A), when incubated with a mixture of guanosine-5'-phosphoro-(2-methylimidazole) (2-MeImpG) and uridine-5'-phosphoro-(2-methylimidazole) (2-MeImpU), facilitates the incorporation of uridine (U) into oligomeric products with low efficiency. If 2-aminoadenosine (aA) is substituted for adenosine in the template, U is incorporated into the products with much higher efficiency. Random copolymers of C and U act as templates for the efficient synthesis of oligomers from 2-MeImpG and 2-MeImpA only if the concentration of substrates is relatively high (0.1 M). The substitution of 2-MeImpA permits the reaction to occur with much lower substrate concentrations. This effect is most prominent for template containing large amounts of U. | Experimental studies have indicated that n-3 fatty acids, including alpha-linolenic acid (18:3 n-3) and long-chain n-3 polyunsaturated fatty acids inhibit mammary tumor growth and metastasis. Earlier epidemiological studies have given inconclusive results about a potential protective effect of dietary n-3 polyunsaturated fatty acids on breast cancer risk, possibly because of methodological issues inherent to nutritional epidemiology. To evaluate the hypothesis that n-3 fatty acids protect against breast cancer, we examined the fatty acid composition in adipose tissue from 241 patients with invasive, nonmetastatic breast carcinoma and from 88 patients with benign breast disease, in a case-control study in Tours, central France. Fatty acid composition in breast adipose tissue was used as a qualitative biomarker of past dietary intake of fatty acids. Biopsies of adipose tissue were obtained at the time of surgery. Individual fatty acids were measured as a percentage of total fatty acids, using capillary gas chromatography. Unconditional logistic regression modeling was used to obtain odds ratio estimates while adjusting for age, height, menopausal status and body mass index. We found inverse associations between breast cancer-risk and n-3 fatty acid levels in breast adipose tissue. Women in the highest tertile of alpha-linolenic acid (18:3 n-3) had an odds ratio of 0.39 (95% confidence intervals [CI] = 0.19–0.78) compared to women in the lowest tertile (trend p = 0.01). In a similar way, women in the highest tertile of docosahexaenoic acid (22:6 n-3) had an odds ratio of 0.31 (95% CI = 0.13-0.75) compared to women in the lowest tertile (trend p = 0.016). Women in the highest tertile of the long-chain n-3/total n-6 ratio had an odds ratio of 0.33 (95% confidence interval = 0.17–0.66) compared to women in the lowest tertile (trend p = 0.0002). In conclusion, our data based on fatty acids levels in breast adipose tissue suggest a protective effect of n-3 fatty acids on breast cancer risk and support the hypothesis that the balance between n-3 and n-6 fatty acids plays a role in breast cancer. © 2001 Wiley-Liss, Inc. | eng_Latn | 27,293 |
The multi-component fingerprint and the biological evaluation of plant-derived material are indispensable for the pharmaceutical field, in food quality control procedures, and in all plant-based products. We investigated the quantitative content of biologically active compounds (anthocyanins and chlorogenic acid) of microwave-assisted blueberry extracts from 14 different Italian cultivars, using validated high-performance liquid chromatography-photodiode array detector (HPLC-PDA) method and routinely instrument configuration. The carbonic anhydrase (CA, EC 4.2.1.1) inhibition profiles against several pharmacologically relevant CA isoforms of blueberry extracts and some bioactive compounds were also investigated. The various cultivars showed a highly variable content in anthocyanins and chlorogenic acid, and their CA inhibitory effects were also highly variable. Overall these data prove that antioxidant natural products found in blueberries may be useful for designing pharmacological agents in whic... | Harpagophytum procumbens has a long story of use for the treatment of inflammatory diseases. Considering both the antiinflammatory effects of H. procumbens in multiple tissues and the stability of harpagoside in artificial intestinal fluid, the aim of the present study was to explore the possible protective role of a microwave-assisted aqueous Harpagophytum extract (1-1000 μg/mL) on mouse myoblast C2C12 and human colorectal adenocarcinoma HCT116 cell lines, and isolated rat colon specimens challenged with lipopolysaccharide (LPS), a validated ex vivo model of acute ulcerative colitis. In this context, we evaluated the effects on C2C12 and HCT116 viability, and on LPS-induced production of serotonin (5-HT), tumor necrosis factor (TNF)-α, prostaglandin (PG)E2 and 8-iso-prostaglandin (8-iso-PG)F2α . Harpagophytum extract was well tolerated by C2C12 cells, while reduced HCT116 colon cancer cell viability. On the other hand, Harpagophytum extract reduced H2 O2 -induced (1 mM) reactive oxygen species (ROS) production, in both cell lines, and inhibited LPS-induced colon production of PGE2 , 8-iso-PGF2α , 5-HT and TNFα. Concluding, we demonstrated the efficacy of a microwave-assisted Harpagophytum aqueous extract in modulating the inflammatory, oxidative stress and immune response in an experimental model of inflammatory bowel diseases (IBD), thus suggesting a rational use of Harpagophytum in the management and prevention of ulcerative colitis in humans. Copyright © 2017 John Wiley & Sons, Ltd. | A model for cochlear mechanics is proposed to take account of its two systems, one passive and one active. The classical passive system stimulates the inner hair cells directly at levels above about 40 dB SL. At intensities below about 60 dB an active process, the 'cochlear amplifier' (CA), somehow provides additional energy that enhances the vibration of a narrow segment of the basilar membrane near the apical foot of the familiar, traveling wave envelope. The outer hair cells are essential for CA. The active system acts like a high-Q acoustic resonator, and it accounts for the great sensitivity and sharp tuning expressed by the 'tips' of neural tuning curves. The tips are selectively vulnerable to anoxia, noise exposure and other trauma. The CA model explains the detection of small differences in time as well as in frequency, the dual character of the electrocochleogram, recruitment of loudness in cochlear hearing impairment, the long latency of normal neural responses near threshold, acoustic emissions (both stimulated and spontaneous) and the locus of TTS in the frequency range above the exposure tone. Both the classical high-intensity system and the active low-level CA system are highly nonlinear and they combine to compress the great dynamic range of hearing into a much narrower range of mechanical movement of the cilia of the inner hair cells. The mechanism of CA is unknown, and the problem remains of how its action can be triggered by submolecular movements near threshold. | eng_Latn | 27,294 |
We have measured the levels of thymine glycol (TG) and thymidine glycol (dTG) in human urine, using an HPLC method. The results show that all 30 specimens examined (including 10 non-neoplastic and 20 neoplastic human urines) contained significant amounts of TG and dTG, average levels (mean +/- SEM) were 0.376 +/- 0.026 and 0.138 +/- 0.009 nmol/kg body weight/day respectively. The average levels of TG and dTG were 0.435 +/- 0.038 and 0.164 +/- 0.017 nmol/kg body weight/day in 10 healthy human urine specimens and 0.347 +/- 0.035 and 0.125 +/- 0.010 nmol/kg body weight/day in 20 neoplastic human urine specimens respectively. No significant differences were found between female and male as well as between the non-neoplastic and neoplastic human urine specimens. There were also wide interindividual variations, which were not age-dependent. | Reactive oxygen species are generated during ischaemia-reperfusion of tissue. Oxidation of thymidine by hydroxyl radicals (HO) leads to the formation of 5,6-dihydroxy-5,6-dihydrothymidine (thymidine glycol). Thymidine glycol is excreted in urine and can be used as biomarker of oxidative DNA damage. Time dependent changes in urinary excretion rates of thymidine glycol were determined in six patients after kidney transplantation and in six healthy controls. A new analytical method was developed involving affinity chromatography and subsequent reverse-phase high-performance liquid chromatography (RP-HPLC) with a post-column chemical reaction detector and endpoint fluorescence detection. The detection limit of this fluorimetric assay was 1.6 ng thymidine glycol per ml urine, which corresponds to about half of the physiological excretion level in healthy control persons. After kidney transplantation the urinary excretion rate of thymidine glycol increased gradually reaching a maximum around 48 h. The excretion rate remained elevated until the end of the observation period of 10 days. Severe proteinuria with an excretion rate of up to 7.2 g of total protein per mmol creatinine was also observed immediately after transplantation and declined within the first 24 h of allograft function (0.35 ± 0.26 g/mmol creatinine). The protein excretion pattern, based on separation of urinary proteins on sodium dodecyl sulphate-polyacrylamide gel electrophorosis (SDS-PAGE), as well as excretion of individual biomarker proteins, indicated nonselective glomerular and tubular damage. The increased excretion of thymidine glycol after kidney transplantation may be explained by ischaemia-reperfusion induced oxidative DNA damage of the transplanted kidney. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 27,295 |
In this study, we report on the development of a method to confirm simultaneously nine of the most commonly abused synthetic corticosteroids in urine based on liquid chromatography-electrospray ionisation mass spectrometry. A considerable simplified sample preparation procedure, including liquid-liquid phase extraction with Extrelut-NT3 columns, provided both excellent sample purification and high overall recoveries. Complete HPLC separations were obtained on a reversed-phase column with 1 mM ammonium acetate-acetonitrile (60:40, v/v) as mobile phase. Mass spectral acquisition was done in the negative ion, and selected ion monitoring modes to identify the drugs with at least three characteristic ions. Detection limits were determined at < or =1 ng/ml and the confirmation limits at 1 to 5 ng/ml. | This paper reviews liquid chromatographic-mass spectrometric (LC-MS) procedures for the screening, identification and quantification of doping agents in urine and other biological samples and devoted to drug testing in sports. Reviewed methods published approximately within the last five years and cited in the PubMed database have been divided into groups using the same classification of the 2004 World Anti-Doping Agency (WADA) Prohibited List. Together with procedures specifically developed for anti-doping analysis, LC-MS applications used in other fields (e.g., therapeutic drug monitoring, clinical and forensic toxicology, and detection of drugs illicitly used in livestock production) have been included when considered as potentially extensible to doping control. Information on the reasons for potential abuse by athletes, on the requirements established by WADA for analysis, and on the WADA rules for the interpretation of analytical findings are provided for the different classes of drugs. | A stopped flow kinetic analysis has been performed with a homogeneous protein fraction of plant glutamate dehydrogenase. The enzyme exerts strong negative cooperativity with ammonium as variable substrate. The limiting initial rate constants for low substrate concentrations, as calculated from the kinetic data, indicate that the catalytic efficiency of the enzyme increases at low ammonium concentrations. From this it becomes evident that the reductive amination reaction is highly adaptive to the ammonium environment. | eng_Latn | 27,296 |
A direct competitive enzyme-linked immunosorbent assay (ELISA) has been developed for detection of diethyl phthalate (DEP). Protein-hapten conjugate was synthesized to produce polyclonal antibodies against DEP. Experimental parameters were optimized, including immunoreaction conditions, the dilution ratio of horseradish peroxidase (HRP)-antigen conjugate, time of the antibody coated, effect of pH, and ionic strength. The limit of detection was 0.096ng/ml, and the linear range was 0.1-3500ng/ml with a regression coefficient (R(2)) of 0.9957. Recoveries were between 96.4 and 106.2%. The cross-reactivities of the anti-DEP antibody to six structurally related phthalate esters were less than 9%. The method was successfully applied to the determination of DEP in tap water, river water (Yangtze River), and leachate from plastic drinking bottles. This immunoassay was highly specific, sensitive, rapid, simple, and suitable for DEP monitoring. The results obtained were compared with those obtained using the high-performance liquid chromatography method. | In this work, three fluorescein-labeled DiBP derivatives (tracers) with different chemical structures and spacer bridges were synthesized and purified by thin-layer chromatography (TLC). Compared with the heterologous tracer, the homologous tracer exhibited more affinity to the antibody. What is more, the tracer concentration and the antibody dilution were further evaluated to improve the sensitivity of fluorescence polarization immunoassay (FPIA). On the basis of sensitive antibody and tracer, a rapid and specific FPIA has been established for the detection of DiBP contamination in the romaine lettuce, which has rarely been reported before. Under the optimal conditions, the developed FPIA showed a good detection range from 8.82 to 2152.84 ng/mL, with a detection limit of 1.77 ng/mL. In addition, the cross-reactivity to several compounds structurally related to DiBP was less than 7.37 %. Therefore, DiBP contamination in spiked romaine lettuce samples was detected by FPIA, with the recovery from 88.28 to 119.11 %. Moreover, when compared with high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA), the results analyzed by the developed FPIA shows a strong reliability and a high correlation value of 0.978 and 0.980, respectively. Thus, this data, combined with rapidity and simplicity of the assay, demonstrates that the established FPIA is a suitable method for high throughput screening of DiBP contamination in the romaine lettuce. | Prodrugs of the short-lived chloroethylating agent 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)hydrazine (90CE) and its methylating analogue 1,2-bis(methylsulfonyl)-1-(methyl)hydrazine (KS90) are potentially useful anticancer agents. This class of agents frequently yields higher ratios of therapeutically active oxophilic electrophiles responsible for DNA O6-guanine alkylations to other electrophiles with lower therapeutic relevance than the nitrosoureas. This results in improved selectivity toward tumors with diminished levels of O6-alkylguanine-DNA alkyltransferase (MGMT), the resistance protein responsible for O6-alkylguanine repair. The formation of O6-(2-chloroethyl)guanine, which leads to the formation of a DNA–DNA interstrand cross-link, accounts for the bulk of the anticancer activity of 90CE prodrugs. Herein, we describe a new decomposition pathway that is available to 90CE but not to its methylating counterpart. This pathway appears to be subject to general/acid base catalysis with phosphate (Pi), phosphomonoesters, and phosphodiesters, being particularly effective. This pathway does not yield a chloroethylating species and results in a major change in nucleophile preference since thiophilic rather than oxophilic electrophiles are produced. Thus, a Pi concentration dependent decrease in DNA–DNA interstand cross-link formation was observed. Changes in 90CE decomposition products but not alkylation kinetics occurred in the presence of Pi since the prebranch point elimination of the N-1 methanesulfinate moiety remained the rate-limiting step. The Pi catalyzed route is expected to dominate at Pi and phosphoester concentrations totaling >25–35 mM. In view of the abundance of Pi and phosphoesters in cells, this pathway may have important effects on agent toxicity, tumor selectivity, and resistance to prodrugs of 90CE. Furthermore, it may be possible to design analogues that diminish this thiophile-generating pathway, which is likely superfluous at best and potentially detrimental to the targeting of hypoxic regions where Pi concentrations can be significantly elevated. | eng_Latn | 27,297 |
Detection of nitroxyl (HNO), the transient one-electron reduced form of nitric oxide, is a significant challenge owing to its high reactivity with biological thiols (with rate constants as high as 109 M–1 s–1). To address this, we report a new thiol-based HNO-responsive trigger that can compete against reactive thiols for HNO. This process forms a common N-hydroxysulfenamide intermediate that cyclizes to release a masked fluorophore leading to fluorescence enhancement. To ensure that the cyclization step is rapid, our design capitalizes on two established physical organic phenomena; the alpha-effect and the Thorpe-Ingold effect. Using this new trigger, we developed NitroxylFluor, a selective HNO-responsive fluorescent probe. Treatment of NitroxylFluor with an HNO donor results in a 16-fold turn-on. This probe also exhibits excellent selectivity over various reactive nitrogen, oxygen, and sulfur species and efficacy in the presence of thiols (e.g., glutathione in mM concentrations). Lastly, we successfully... | This study describes an aptamer based assay for the mycotoxin ochratoxin A (OTA). The method is based on the use of an OTA-specific aptamer, exonuclease (Exo) III, SYBR Gold as a fluorescent probe, and a complementary strand that specifically combines with the aptamer. In the presence of OTA, the aptamer and OTA hybridize, thereby resulting in the formation of ssDNA, which is not digested by Exo III. Intense fluorescence is observed after addition of SYBR Gold (best measured at excitation/emission wavelengths of 495/540 nm). Fluorescence increases linearly with the log of the OTA concentration in the range from 8 to 1000 ng·mL-1. The detection limit is 4.7 ng·mL-1. The assay was applied to the determination of OTA in diluted [2%(v/v)] red wine, and recoveries and RSDs ranged between 93.5% and 113.8%, and between 3.2% and 5.7%, respectively. Graphical abstract In the presence of ochratoxin A (OTA), specific combinations of aptamer and OTA may occur and result in DNA double strands being untied, which avoids being digested by Exo III. Intense fluorescence is observed after SYBR Gold addition. | Impaired gastric motility ascribable to a defective nitric oxide (NO) production has been reported in dystrophic (mdx) mice. Since relaxin upregulates NO biosynthesis, its effects on the motor resp... | eng_Latn | 27,298 |
In this work, an octagonal Penrose-type photonic quasi-crystal fiber (PQF) with dual-cladding is proposed. By optimizing three geometric degrees of freedom, the PQF exhibits ultra-flattened near-zero dispersion of 0.014±0.293 ps/nm/km, ultra-low order confinement loss of 10−4 dB/km, and large effective mode area of over 16.2 μm2 in a broadband of wavelength from 1.27 to 1.67 μm, covering almost all optical communication bands. At the common communication wavelength 1.55 μm, completely opposite trends of the dispersion and the confinement loss varying with the air-filling factor in the inner cladding are demonstrated. In addition, the robustness of optical properties including dispersion, confinement loss, and effective mode area in this PQF is discussed, assuming a deviation ±3% of all air holes. | In this Letter, a non-Hermitian two-dimensional photonic crystal flat lens is proposed. The negative refraction of the second band of photonic crystal is utilized to realize super-resolution imaging of the point source. Based on the principles of non-Hermitian systems, a negative imaginary part is introduced into the imaging frequency, in which case the imaging intensity and resolution are improved. The results indicate that the non-Hermitian system provides a new method to improve the imaging performance of the photonic crystal lens. | The oxidative polymorphism of debrisoquine (DBQ) has been determined in 89 patients with colo-rectal cancer and in 556 normal control subjects. Four patients and 34 controls, with a metabolic ratio >12.6, were classified as poor metabolisers of DBQ (n.s.). | eng_Latn | 27,299 |
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