Current Issue : October - December Volume : 2015 Issue Number : 4 Articles : 7 Articles
Transporter proteins expressed in the gastrointestinal tract play a major role in the oral absorption of some\ndrugs, and their involvement may lead to drugââ?¬â??drug interaction (DDI) susceptibility when given in combination\nwith drugs known to inhibit gut wall transporters. Anticipating such liabilities and predicting the\nmagnitude of the impact of transporter proteins on oral drug absorption and DDIs requires quantification\nof their expression in human intestine, and linking these to data obtained through in vitro experiments.\nA quantitative targeted absolute proteomic method employing liquid chromatography coupled to tandem\nmass spectrometry (LCââ?¬â??MS/MS) together with a quantitative concatenation (QconCAT) strategy to\nprovide proteotypic peptide standards has been applied to quantify ATP1A1 (sodium/potassium-ATPase;\nNa/K-ATPase), CDH17 (human peptide transporter 1; HPT1), ABCB1 (P-glycoprotein; P-gp), ABCG2 (breast\ncancer resistance protein; BCRP), ABCC2 (multidrug resistance-associated protein 2; MRP2) and SLC51A\n(Organic Solute Transporter subunit alpha; OST-), in human distal jejunum (n = 3) and distal ileum\n(n = 1) enterocyte membranes. Previously developed selected reaction monitoring (SRM) schedules were\noptimised to enable quantification of the proteotypic peptides for each transporter. After harvesting\nenterocytes by calcium chelation elution and generating a total membrane fraction, the proteins were\nsubjected to proteolytic digestion. To account for losses of peptides during the digestion procedure, a\ngravimetric method is also presented. The linearity of quantifying the QconCAT from an internal standard\n(correlation coefficient, R2 = 0.998) and quantification of all target peptides in a pooled intestinal quality\ncontrol sample (R2 ?\n0.980) was established. The assay was also assessed for within and between-day\nprecision, demonstrating a <15% coefficient of variation for all peptides across 3 separate analytical runs,\nover 2 days. The methods were applied to obtain the absolute abundances for all targeted proteins. In\nall samples, Na/K-ATPase, HPT1, P-gp and BCRP were detected above the lower limit of quantitation (i.e.,\n>0.2 fmol/g membrane protein). MRP2 abundance could be quantified in distal jejunum but not in the\ndistal ileum sample. OST- was not detected in 2 out of 3 jejunum samples. This study highlights the\nutility of a QconCAT strategy to quantify absolute transporter abundances in human intestinal tissues....
Lung cancer is one of the most common causes of cancer death, for which no validated tumor biomarker is sufficiently accurate to\nbe useful for diagnosis. Additionally, the metabolic alterations associated with the disease are unclear. In this study, we investigated\nthe construction, interaction, and pathways of potential lung cancer biomarkers using metabolomics pathway analysis based on the\nKyoto Encyclopedia of Genes and Genomes database and the Human Metabolome Database to identify the top altered pathways\nfor analysis and visualization. We constructed a diagnostic model using potential serum biomarkers from patients with lung\ncancer. We assessed their specificity and sensitivity according to the area under the curve of the receiver operator characteristic\n(ROC) curves, which could be used to distinguish patients with lung cancer from normal subjects. The pathway analysis indicated\nthat sphingolipid metabolism was the top altered pathway in lung cancer. ROC curve analysis indicated that glycerophospho-N-arachidonoyl\nethanolamine (GpAEA) and sphingosine were potential sensitive and specific biomarkers for lung cancer diagnosis\nand prognosis. Compared with the traditional lung cancer diagnostic biomarkers carcinoembryonic antigen and cytokeratin 19\nfragment, GpAEA and sphingosine were as good or more appropriate for detecting lung cancer. We report our identification of\npotential metabolic diagnostic and prognostic biomarkers of lung cancer and clarify the metabolic alterations in lung cancer....
A simple and rapid liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay method has been developed and validated for quantification of protease inhibitor atazanavir in rabbit plasma. Saquinavir was used as an internal standard. The analytes were extracted from rabbit plasma samples by solid-phase extraction technique using Orpheus C18 extraction cartridges. The reconstituted samples were chromatographed on a C18 column by using 85:15 (v/v) mixture of methanol and 5 mM ammonium acetate as the mobile phase at a flow rate of 0.9 ml/min. The calibration curves obtained were linear (r2 0.99) over the concentration range 50.5 - 5995.2 ng/ml. The results of the intra and inter-day precision and accuracy studies were well within the acceptable limits. The proposed method was found to be applicable to pharmacokinetic studies....
Abstract\nBackground: Development of simple, rapid, and sensitive assay for the determination of loratadine\nin order to investigate its pharmacokinetic parameters in human plasma and its application in\nbioequivalence study of Loratadine 10mg Oral Disintegrated Tablets manufactured locally (test) and\noriginally (Reference).\nMethods: After extraction of loratadine from human plasma, it was chromatographed with mobile\nphase consisting of 0.5% formic acid: Acetonitrile (10:90 V/V) at flow rate 0.6ml/min, ESI positive mode,\nand m/z 383?337 for Loratadine. The bioequivalence study was conducted in a Two-Way Open-Label,\nCrossover design involving 24 volunteers. The criteria used to assess bioequivalence of the two products\nwere AUC0-t, AUC0-inf, Cmax, and Tmax.\nResults: the described method of analysis showed that the average recovery of Loratadine from human\nplasma was 102.685%. The limit of Quantitation was 0.05ng/ml, and the correlation coefficient (r2) was\nequal to 0.999893.\nStatistical analysis (ANOVA) of the measured parameters showed that there was no significant difference\nbetween the two products.\nConclusion: The LC/MS/MS method presented is direct, simple, reproducible, sensitive, and linear\nfor the determination of Loratadine in human plasma, and is adequate for clinical pharmacokinetic\nstudies, besides the test product was found to be bioequivalent to the reference and both products can be\nconsidered interchangeable in medical practice....
Xiamenmycin A is an antifibrotic leading compound with a benzopyran skeleton\nthat is isolated from mangrove-derived Streptomyces xiamenensis. As a promising small\nmolecule for fibrotic diseases, less information is known about its metabolic characteristics\nin vivo. In this study, the time-course of xiamenmycin A in mouse plasma was investigated\nby relative quantification. After two types of administration of xiamenmycin A at a single\ndose of 10 mg/kg, the plasma concentrations were measured quantitatively by LC-MS/MS.\nThe dynamic changes in the xiamenmycin A concentration showed rapid absorption and\nquick elimination in plasma post-administration. Four metabolites (M1ââ?¬â??M4) were identified\nin blood by UPLC-QTOF-MS, and xiamenmycin B (M3) is the principal metabolite in vivo,\nas verified by comparison of the authentic standard sample. The structures of other\nmetabolites were identified based on the characteristics of their MS and MS/MS data. The\nnewly identified metabolites are useful for understanding the metabolism of xiamenmycin A\nin vivo, aiming at the development of an anti-fibrotic drug candidate for the therapeutic\ntreatment of excessive fibrotic diseases....
The studies of drugs that could constitute a palliative to spinal cord injury (SCI) are a continuous and increasing demand in\nbiomedicine field from developed societies. Recently we described the chemical synthesis and antiglioma activity of synthetic\nglycosides. A synthetic sulfated glycolipid (here IG20) has shown chemical stability, solubility in polar solvents, and high inhibitory\ncapacity over glioma growth. We have used mass spectrometry (MS) to monitor IG20 (????/???? = 550.3) in cells and tissues of the\ncentral nervous system (CNS) that are involved in SCI recovery. IG20 was detected by MS in serum and homogenates from CNS\ntissue of rats, though in the latter a previous deproteinization step was required.The pharmacokinetic parameters of serum clearance\nat 24 h and half-life at 4 h were determined for synthetic glycoside in the adult rat using MS. A local administration of the drug\nnear of spinal lesion site is proposed....
Purpose The effects of chitosan hydrochloride on the oral absorption\nof acyclovir in humans were studied to confirm the absorption\nenhancing effects reported for in vitro and rat studies, respectively.\nMethods A controlled, open-label, randomized, 3-phase study\nwas conducted in 12 healthy human volunteers. Zovirax 200 mg\ndispersible tablets co-administered with doses of 400 and\n1000 mg chitosan HCl were compared with Zovirax only.\nResults The expected increased absorption of acyclovir was not\nobserved. On the contrary, mean area under the plasma\nconcentration-time curve (AUC0-12 h) and maximal plasma concentration\n(Cmax) decreased following concomitant chitosan intake\n(1402 versus 1017 and 982.0 ng?h/ml and 373 versus 208\nand 235 ng/ml, respectively). In addition, Tmax increased significantly\nin presence of 1000 mg of chitosan from 1 to 2 h.\nConclusions The results of this study in human volunteers did\nnot confirm an absorption enhancing effect of chitosan. Reference\nvalues were comparable to literature data, whereas addition of\nchitosan resulted in significant opposite effects on Cmax, Tmax and\nAUC. Additional studies are needed to investigate the cause of the\ndiscrepancy. The observed variability and complex potential interactions\nmay complicate the use of chitosan HCl in oral pharmaceutical\nformulations....
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