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LC-MS Analysis (lc-m + analysis)
Selected AbstractsA Fatal Case of Suspected Anaphylaxis with Cefoperazone and Sulbactam: LC-MS AnalysisJOURNAL OF FORENSIC SCIENCES, Issue 1 2008Kenji Tsujikawa M.S. Abstract: Cefoperazone and sublactam are prescribed in combination and used in the treatment of moderate to severe bacterial infections. Serious anaphylaxis is a rare side effect. This report describes a fatal case of suspected anaphylaxis after intravenous administration of a combination of the two drugs. Heart blood was analyzed for cefoperazone by protein precipitation with acetonitrile and by liquid-liquid precipitation for sublactam after protein precipitation with aqueous acetonitrile, followed by tandem mass spectrometry in the product ion scan mode for identification and by liquid chromatography mass spectrometry in the selected ion monitoring mode for quantitation. Calibration curves for cefoperazone and sublactam were linear over the range 0.07 to 1.93 and 0.046 to 0.914 ,g/ml respectively. The decedent's blood concentrations of cefoperazone and sublactam were 0.368 and 0.143 ,g/ml respectively. As these concentrations were below concentrations reported after single dosing studies and below those considered to be minimally inhibitory, death was presumed to have been caused by hypersensitivity and not an overdose. In conclusion, this procedure is useful for detecting and quantitating cefoperazone and sublactam in postmortem blood and may be useful in the evaluation of anaphylaxis. [source] Differentiation of Closely Related Fungi by Electronic Nose AnalysisJOURNAL OF FOOD SCIENCE, Issue 6 2007K. Karlshøj ABSTRACT:, In this work the potential of electronic nose analysis for differentiation of closely related fungi has been described. A total of 20 isolates of the cheese-associated species Geotrichum candidum, Penicillium camemberti, P. nordicum, and P. roqueforti and its closely related species P. paneum, P. carneum as well as the noncheese-associated P. expansum have been investigated by electronic nose, GC-MS, and LC-MS analysis. The isolates were inoculated on yeast extract sucrose agar in 20-mL headspace flasks and electronic nose analysis was performed daily for a 7-d period. To assess which volatile metabolites the electronic nose potentially responded to, volatile metabolites were collected by diffusive sampling overnight onto tubes containing Tenax TA, between the 7th and 8th day of incubation. Volatiles were analyzed by gas chromatography coupled to mass spectrometry and the results indicated that mainly alcohols (ethanol, 2-methyl-1-propanol, and 3-methyl-1-butanol) and ketones (acetone, 2-butanone, and 2-pentanone) were produced at this stage. The volatile metabolite profile proved to be species specific. Nonvolatile metabolites were collected on the 8th day of incubation and mycotoxin analysis was performed by high pressure liquid chromatography coupled to a diode array detector and a time of flight mass spectrometer. Several mycotoxins were detected in samples from the species P. nordicum, P. roqueforti, P. paneum, P. carneum, and P. expansum. Differentiation of closely related mycotoxin producing fungi incubated on yeast extract sucrose agar has been achieved, indicating that there is a potential for predicting production of mycotoxins on food and feedstuffs by electronic nose analysis. [source] Oxidative metabolism by Thalassiosira weissflogii (Bacillariophyceae) of a diol-ester of okadaic acid, the diarrhetic shellfish poisoningJOURNAL OF PHYCOLOGY, Issue 2 2000Anthony J. Windust Previous investigations into the comparative toxicity of the diarrhetic shellfish poisoning (DSP) toxins to Thalassiosira weissflogii (Grun.) Fryxell et Hasle found that this diatom oxidatively metabolized okadaic acid diol-ester (OA diol-ester) to a more water-soluble product. This oxidative transformation of OA diol-ester by the diatom is significant for two reasons. First, it is known that dinophysistoxin-4 (DTX-4), the primary DSP toxin produced by the dinoflagellate Exuviaella lima (Ehr.) Butschli, will be hydrolyzed to the diol-ester following cell rupture (e.g. ingestion by a predator). Second, it implies that the ester, an uncharged, lipophilic intermediate, can easily enter cells and therefore may play an important role in the uptake and transfer of DSP toxins through the food web. It has been suggested that the water soluble DTX-4 may also be the form in which DSP toxins are excreted from the producing cell. Therefore, the stability of DTX-4 was examined when incubated either in fresh seawater medium into which washed cells of E. lima were introduced or in seawater medium conditioned by E. lima cells. Rapid hydrolysis of DTX-4 to the diol-ester took place in both cases. Thus, regardless of the route by which DTX-4 is liberated from the cell, either by cell disruption or excretion, the diol-ester will be the dominant form of the toxin to challenge associated organisms. To examine the metabolism of OA diol-ester by T. weissflogii in more detail, serial cultures of the diatom were challenged with OA diol-ester at a concentration of 2.0 ,g·mL,1. The metabolism and fate of the diol-ester in both cellular and medium fractions were monitored over 3 days using liquid chromatography with either ultraviolet (LC-UV) or mass spectrometric (LC-MS) detection. During the course of the experiment, all of the diol-ester was metabolized. LC-MS analysis revealed the presence of multiple oxidative products of OA diol-ester in the medium fraction, including a carboxylic acid derivative. The major metabolites were isolated in sufficient quantity to permit structural elucidation by NMR and MS. All the metabolites identified resulted from oxidation of the diol-ester side chain with the primary sites of attack at the terminal, subterminal, and unsaturated carbons. OA was found in both cellular and medium fractions, and its production was directly correlated with the metabolism of the diol-ester. The relative partitioning of both OA diol-ester and its oxidation products between cells and medium supports the contention that OA diol-ester can readily enter cells, be metabolized, and then excreted in more water-soluble forms. [source] In vivo and in vitro activities of the seed extract of Piper guineense Schum. and Thonn. against skin and gill monogenean parasites of gold,sh (Carassius auratus auratus)PHYTOTHERAPY RESEARCH, Issue 10 2004A. P. Ekanem Abstract Methanol extracts of the seeds of Piper guineense (Piperaceae) were active against gold,sh (Carassius auratus auratus L. Pisces Cyprinidae) monogenean parasites. The seed extract of P. guineense was administered at different concentrations (0.5,2.0 mg/L) under in vivo and in vitro conditions. There was a higher ef,cacy of the effects of the extracts against ,sh parasites under in vitro situations than under in vivo. Three major compounds (piperanine, N -isobutyl (E,E)-2,4 decadienamide and ,,,, -dihydrowasanine) were identi,ed from the seed extract of Piper guineense by LC-MS analysis. Copyright © 2004 John Wiley & Sons, Ltd. [source] The phosphoproteome of Fusarium graminearum at the onset of nitrogen starvationPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 1 2010Christof Rampitsch Abstract Fusarium graminearum grown under stress, such as nutrient deprivation, activates, among others, the trichothecene pathway that produces the mycotoxin deoxynivalenol and its derivatives. The kinase inhibitor staurosporine reduced the production of trichothecenes by 39% compared with control in vitro. On the other hand, phosphatase inhibitor okadaic acid increased the amount by 72% compared with the control in vitro. This suggests that phosphorylation events are involved in the signalling pathway, leading to the activation of the trichothecene pathway. Three approaches were used to study the phosphoproteome of F. graminearum under nitrogen-limiting conditions: 2-DE (2-DE: IEF×SDS-PAGE) in combination with MS protein identification; SDS-PAGE in combination with off-line IMAC and TiO2 enrichment and gel electrophoresis LC-MS analysis; and a gel-free approach using strong anion exchange chromatography, IMAC and LC-MS. A total of 348 phosphorylation sites localized in 301 peptides from 241 proteins were identified. By 2-DE, 20 phosphoproteins were identified, nine of which underwent changes during the time course examined. Using gel electrophoresis LC-MS 231 phosphopeptides were identified from three samples (ten gel slices each) at time points of nitrogen starvation t=0, 6, and 12,h. The gel-free analysis added 70 peptides from 65 proteins to the total. Proteins of unknown function and enzymes of known function comprised the largest groups overall. Ten protein kinases and seven transcription factors were identified. This is the first reported phosphoproteome of F. graminearum. [source] LC-MS analysis for the components captured by ECV304 cell from extract of Aconitum szechenyianum Gay.BIOMEDICAL CHROMATOGRAPHY, Issue 4 2009Jiang-Feng Yuan Abstract A novel method of cell affinity screening (CAS), cell affinity capture coupled with LC-MS analysis, was developed for screening the bioactive compounds related to cardiovascular diseases from the natural product libraries. One of the major characteristics lies in its function in affinity-capturing and separating the bioactive components from the natural product libraries in vitro. Another characteristic is its use in analyzing and identifying the target compounds, by employing high-performance liquid chromatography and mass spectrometry. CAS was used for screening the bioactive components from the alkaloid extract derived from Aconitum szechenyianum Gay. Of the five components found to be bound to the oxidative-damaged endothelial cells, the two compounds identified, mesaconitine and aconitine, were recognized in the literature as being related to cardiovascular diseases. Copyright © 2008 John Wiley & Sons, Ltd. [source] The influence of CYP2B6, CYP2C9 and CYP2D6 genotypes on the formation of the potent antioestrogen Z-4-hydroxy-tamoxifen in human liverBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 2 2002Janet K. Coller Aims, To investigate in a large panel of 50 human liver samples the contribution of CYP2C9, CYP2D6, and CYP3A4 to the overall formation of the potent antioestrogen Z-4-hydroxy-tamoxifen, and how various genotypes affect its formation from tamoxifen. Methods, The formation of Z-4-hydroxy-tamoxifen from 10 µm tamoxifen was studied in human liver microsomes (n=50), characterized for CYP2B6, CYP2C9, CYP2D6 and CYP3A4 expression, and CYP2B6, CYP2C9 and CYP2D6 genotype. The effect of chemical and monoclonal antibody inhibitors, and the formation in supersomes expressing recombinant CYP isoforms was also investigated. Z-4-hydroxy-tamoxifen was quantified using LC-MS analysis. Results, Z-4-hydroxy-tamoxifen was formed by supersomes expressing CYP2B6, CYP2C9, CYP2C19 and CYP2D6, but not CYP3A4. In agreement with these data, the mean formation of Z-4-hydroxy-tamoxifen was inhibited 49% by sulphaphenazole (P=0.001), 38% by quinidine (P<0.05) and 13% by monoclonal antibody against CYP2B6 (MAB-2B6, P<0.05). Furthermore, Z-4-hydroxy-tamoxifen formation significantly correlated with both CYP2C9 expression (rs=0.256, P<0.05) and CYP2D6 expression (rs=0.309, P<0.05). Genotypes of CYP2D6, CYP2B6 and CYP2C9 had an effect on metabolite formation in such a way that samples with two nonfunctional CYP2D6, or two variant CYP2C9 or CYP2B6 alleles, showed lower enzyme activity compared with those with two functional or wild-type alleles, (5.0 vs 9.9 pmol mg,1 protein min,1, P=0.046, 5.1 vs 9.9 pmol mg,1 protein min,1, P=0.053, and 6.8 vs 9.4 pmol mg,1 protein min,1, P=0.054, respectively). CYP2D6 and CYP2C9 contribute on average 45 and 46%, respectively, to the overall formation of Z-4-hydroxy-tamoxifen. Conclusions,CYP2B6, CYP2C9 and CYP2D6 genotypes all affected Z-4-hydroxy-tamoxifen formation and can predict individual ability to catalyse this reaction. [source] | |||||||||||||