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81.
《Analytical letters》2012,45(3):315-321
Abstract A high-performance liquid chromatography assay was developed for the purpose of examining xanthine, hypoxanthine, uridine, thymidine, allopurinol, and oxypurinol in serum of patients with advanced carcinoma treated with methorexate and 5-fluorouracil. After the addition of an internal standard, serum samples were extracted of purines and pyrimidines with trichloroacetic acid and neutralized with tert-amine. Aliquots of the extracted serum were injected onto a C18 reverse-phase column and purines and pyrimidines were eluted with a gradient of MeOH/H2O and KH2PO4 solutions. Absorbance was detected with a variable-wavelength UV spectrophotometer at 254 nm and 280 nm. This assay can be readily applied to quantitate baseline and treatment-induced variations in serum purine and pyrimidine levels which may correlate with clinical response and/or toxicity in patients with cancer. 相似文献
82.
Evaluation of a sensitive HPLC method for the determination of Malondialdehyde, and application of the method to different biological materials 总被引:1,自引:0,他引:1
G. A. Khoschsorur B. M. Winklhofer-Roob H. Rabl Th. Auer Z. Peng R. J. Schaur 《Chromatographia》2000,52(3-4):181-184
Summary Reactive oxygen species (ROS), important mediators of cell and tissue injury during inflammation, are produced by several
types of inflammatory cells. The formation of ROS can be monitored by detection of lipid peroxidation products. The extremely
broad spectrum of biological effects of aldehydic lipid peroxidation products has necessitated the development of a technique
that enables the sensitive routine quantitation of aldehydes formed in biological materials. Malondialdehyde (MDA) is a by-product
of enzymatic eicosanoid formation and an end-product of nonenzymatic peroxidation of polyunsaturated fatty acids with three
or more bisallylic double bonds. The determination of the thiobarbituric acid derivative of MDA (TBA-MDA) is a widely used
method for estimating overall lipid peroxidation. We describe a rapid, isocratic, simple, and sensitive high-performance liquid
chromatographic (HPLC) method with spectrofluorimetric detection for measurement of MDA-TBA in human biological samples such
as plasma, urine, wound secretions, amniotic fluid, sputum and tissue samples. By use of this method, picomole quantities
of MDA can be readily and specifically detected in different biological materials. Coefficients of variation of repeated MDA-TBA
assays were 4.4% within run and 6.9% from run to run. Reference values are given for a variety of human body fluids and for
rat tissues. 相似文献
83.
Solid-phase microextraction coupled with microcolumn liquid chromatography for the analysis of amitriptyline in human urine 总被引:1,自引:0,他引:1
Summary Solid-phase microextraction (SPME) is a solvent-free sample-preparation technique that enables isolation and pre-concentration
of analytes from a sample on a thin film coating a fused-silica fiber. In this study SPME coupled with microcolumn liquid
chromatography (micro LC) has been used for the determination of four tricyclic antidepressants (amitriptyline, imipramine,
nortriptyline, and desipramine) in human urine. SPME conditions which affect extraction efficiency were optimized, and under
the optimum conditions the system was a few hundred times more sensitive than direct LC analysis without SPME. For amitriptyline
the detection limit was 3 ng mL−1 and the calibration curve was linear in the range of 5–500 ng mL−1. The SPME-micro LC method has been applied to the analysis of amitriptyline in patient’s urine. 相似文献
84.
Anthropogenic emissions, such as those from combustion of fossil fuel, waste incineration and industrial use, contribute to higher levels of metal pollutants, including Cd, Pb and Sb, in the urban environment. These widespread and persistent environmental pollutants have the potential for developmental and reproductive toxicity. Health risks are particularly associated with exposure in utero and the early years of life, since the developing organism is at greater risk from permanent damage, and both absorption and retention can be considerably greater in infants than adults. In order to assess risk to humans, the information on environmental levels of pollutants (environmental monitoring) should be integrated with information on biomarkers of exposure, effect or susceptibility in biological fluids or tissues (biological monitoring). The analysis of tissue from the target organ obtained at autopsy provides a direct record of the accumulation of toxins and allows temporal and geographical trends to be studied. Few literature reports on tissue content of potentially toxic elements include data on newborns and young children since collections of autopsy samples in this age range are rare. Existing data are sometime questionable, because of inadequate sensitivity of the analytical techniques, insufficient control of contamination and lack of validation. Our recent work aimed to establish reliable reference values for the content of Cd, Pb and Sb in the liver of pediatric subjects. 相似文献
85.
In this paper, a finite crack with constant length (Yoffe type crack) propagating in a functionally graded coating with spatially varying elastic properties bonded to a homogeneous substrate of finite thickness under anti-plane loading was studied. A multi-layered model is employed to model arbitrary variations of material properties based on two linearly-distributed material compliance parameters. The mixed boundary problem is reduced to a system of singular integral equations that are solved numerically. Some numerical examples are given to demonstrate the accuracy, efficiency and versatility of the model. The numerical results show that the graded parameters, the thicknesses of the interfacial layer and the two homogeneous layers, the crack size and speed have significant effects on the dynamic fracture behavior. 相似文献
86.
《印度化学会志》2021,98(6):100082
This study has investigated docking-based 2D- and 3D-quantitative structure-activity relationships (QSARs) for a range of 53 hydroxybenzamide analogues as anti- Human adenoviruses (HAdVs). The best 3D-QSAR (Schrodinger, LLC, NY, 2020) and 2D-QSAR models were obtained for the training set and were found to be statistically significant, with cross-validated coefficients (q2) of 0.6775 and 0.7875, and coefficients of determination (r2) of 0.8106 and 0.8122, respectively. Our in-silico docking and virtual screening studies revealed significant higher binding affinity of dataset molecule 34 (-141.444 kcal/mol) and hit ZINC01088642 (-114.357 kcal/mol) with 4PIE protein than the standard drugs. In in-silico ADME/toxicity studies, molecule 34 and proposed hit ZINC01088642 were found safe with good intestinal absorption, aqueous solubility, medium blood–brain barrier (BBB), no eye corrosion, no skin irritancy, and non-mutagenic profiles. Molecular dynamics analysis showed good stability of complex, hit ZINC01088642 with protein, 4PIE over the simulation period of 20 ns. We believe that further experimental, as well as in-vitro investigation, will shed more lights on the identification of ZINC01088642 as a potential human adenovirus agent. 相似文献
87.
Li Yao Saijing Zheng Yafeng Guan Jun Yang Baizhan Liu Weimiao Wang Xiaolan Zhu 《Analytica chimica acta》2013
Determination of the tobacco-specific nitrosamine metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and its N- and O-glucuronides (NNAL-N-Gluc and NNAL-O-Gluc) is important for toxicology analysis of tobacco smoke induced carcinogenicity and the understanding of detoxification mechanisms of the carcinogenic nitrosamine in humans. But previously reported indirect measurement methods involving enzymolysis and base treatment steps were tedious and time-consuming. In this work, a direct measurement method for simultaneous determination of urinary NNAL, NNAL-N-Gluc and NNAL-O-Gluc by liquid chromatography–tandem mass spectrometry (LC–MS/MS) in a single run was developed for the first time without the need to perform enzymatic or base hydrolysis. Urine samples were purified using dichloromethane and further extracted by solid-phase extraction. Then they were analyzed by LC–MS/MS operated in electrospray positive ionization mode. Chromatographic separation was achieved on a Phenomenex Kinetex PFP column within 6 min. The proposed method was validated and the results demonstrated that the method can produce satisfactory recoveries and reproducibility for the analytes. The applicability of this newly developed method was investigated for the simultaneous analysis of the three metabolites in smokers’ urine and the obtained results were comparable to those detected using the conventional enzymolysis method. 相似文献
88.
89.
Analysis of two previously described polymorphic Alu insertions (Sb19.3 and NBC3) in world-wide human populations generated genotypic frequencies grossly in violation of Hardy-Weinberg equilibrium expectations. GenBank searches at the National Center for Biotechnology Information (NCBI) and sequencing analyses revealed that samples homozygous for the Sb19.3 Alu insertion amplify a band indistinguishable in size to the lack of insertion amplicon, corresponding to a paralogous locus on chromosome 4. This locus displays a very similar sequence (84%) to that flanking the Sb19.3 Alu insertion located at chromosome 19. Moreover, we have determined that NBC3, a different Alu insertion, is not located in the pseudoautosomal region of the Y-chromosome, as previously reported, but in position Yq11.2. Also, the band that mimics the lack of insertion amplicon corresponds to a paralogous locus located at chromosome X with a similarity of 92% to the sequence flanking the NBC3 Alu insertion. Finally, the utilization of newly designed primers avoided amplification from the paralogous loci and allowed a reliable assignation of genotypes for both loci. Unlike previously reported, using our new primers the Y-specific locus NBC3 was found not to be polymorphic in the populations analyzed. 相似文献
90.
Identification of selenium species in urine by ion-pairing HPLC–ICP–MS using laboratory-synthesized standards 总被引:1,自引:0,他引:1
Wrobel K Wrobel K Kannamkumarath SS Caruso JA 《Analytical and bioanalytical chemistry》2003,377(4):670-674
This study focused on the detection/identification of possible selenium metabolites in human urine. Organoselenium compounds not commercially unavailable were synthesized and characterized by electrospray mass spectrometry. Separation of selenomethionine, methylselenomethionine, trimethylselonium, selenoethionine, and selenoadenosylmethionine was achieved by ion-pairing HPLC with a mobile phase of 2 mmol L–1 hexanesulfonic acid, 0.4% acetic acid, 0.2% triethanolamine (pH 2.5), and 5% methanol. The column effluent was introduced on-line to inductively coupled plasma–mass spectrometry for selenium-specific detection (77Se and 78Se). For selenium speciation in urine, solid-phase extraction was carried out using C18 cartridges modified with hexanesulfonic acid. Selective retention of cationic species was observed from acidified urine (perchloric acid, pH 2.0). After elution with methanol, evaporation, and dissolution in the mobile phase, the sample was introduced to the HPLC–ICP–MS system and the chromatographic peaks were assigned by adding standards. The species identified in urine were selenomethionine, trimethylselonium ion, and selenoadenosylmethionine. The last species was detected for the first time and our results suggest that selenomethionine might enter the metabolic pathway of its sulfur analog in the activated methylation cycle.Kazimierz Wrobel and Katarzyna Wrobel are on the leave from the Institute of Scientific Research, University of Guanajuato, L. de Retana No. 5, 36000 Guanajuato, Gto., Mexico 相似文献