Drugs online research references
Biochim Biophys Acta. 1998 Feb 16;1390(2):149-59.
Metabolic fate of exogenous diacylglycerols in A10 smooth muscle cells.
Chuang M, Severson DL.
Smooth Muscle Research Group, Faculty of Medicine, The University of Calgary, 3330 Hospital Drive NW, Calgary, Alta., Canada.
The metabolic fate of exogenous diacylglycerols, 1-palmitoyl-2-[1-14C]oleoyl-sn-glycerol (2-[14C]POG) and 1-stearoyl-2-[1-14C]arachidonoyl-sn-glycerol (2-[14C]SAG), was determined after incubation of A10 smooth muscle cells with liposomal suspensions. Hydrolysis through a diacylglycerol (DG) lipase pathway was the predominant metabolic fate; more than 80% of cell-associated radioactivity from 2-[14C]POG and 2-[14C]SAG was recovered in lipolytic products, monoacylglycerol (MG) and fatty acids (FA), which were present in the incubation medium. Hydrolysis of 2-[14C]POG was reduced completely by tetrahydrolipstatin, a lipase inhibitor. Very little radioactivity from either 2-[14C]POG or 2-[14C]SAG was incorporated into triacylglycerol or phospholipids. DG lipase and kinase activities were measured by in vitro enzyme assays. 1-[1-14C]Palmitoyl-2-oleoyl-sn-glycerol (1-[14C]POG) was phosphorylated (kinase activity) to a greater extent than 2-[14C]SAG in assays with both soluble and particulate subcellular fractions from A10 cells. DG lipase activity (hydrolysis of 1-[14C]POG and 2-[14C]SAG) was markedly stimulated by the addition of 20 mM MgCl2 and 20 mM ATP to the assay. Under optimal assay conditions, DG lipase activity exhibited little substrate specificity. Our findings indicate that exogenous DG are mainly hydrolyzed by DG and MG lipases in A10 smooth muscle cells; as a result, signalling mechanisms responding to DG second messengers will be attenuated. Copyright 1998 Elsevier Science B.V.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9507099&dopt=Abstract
word match xenical online literature
J Chromatogr B Biomed Sci Appl. 1998 Apr 24;708(1-2):121-9.
Quantitative liquid chromatographic-tandem mass spectrometric determination of orlistat in plasma with a quadrupole ion trap.
Wieboldt R, Campbell DA, Henion J.
Analytical Toxicology, Cornell University, New York State College of Veterinary Medicine, Ithaca 14850, USA.
This report evaluates the use of a quadrupolar ion trap for quantitation in a bioanalytical laboratory. The evaluation was accomplished with the cross-validation of an LC-MS-MS quantitative method previously validated on a triple quadrupole mass spectrometer. The method was a multi-level determination of the anti-obesity drug, orlistat, in human plasma. The method has been refined previously on a triple quadrupole instrument to provide rapid sample throughput with robust reproducibility at sub-nanogram detection limits. Optimization of the method on the ion trap required improved chromatographic separation of orlistat from interfering plasma matrix components coextracted during the initial liquid-liquid extraction of plasma samples. The ion trap produces full-scan collision-induced dissociation mass spectra containing characteristic orlistat fragment ions that are useful for quantitation. Data collection on the ion trap required a precursor ion isolation width of 3.0 Da and optimal quantitative results were obtained when three fragment ions were monitored with a 1.8 Da window for each ion. Although a direct cross-validation between the ion trap and the tandem triple quadrupole mass spectrometer was not possible, quantitative results for orlistat comparable to those obtained from the triple quadrupole instrument were achieved by the ion trap with the modified method. The limit of quantitation for orlistat in plasma on the ion trap was 0.3 ng ml(-1) with a linear dynamic range of 0.3 to 10 ng ml(-1). Precision and accuracy varied from 4 to 15% over the quantitation range. The overall results provide an example of the utility of an ion trap in bioanalytical work.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9653954&dopt=Abstract
word match xenical online literature
J Lipid Res. 1998 Nov;39(11):2135-42.
Lipoprotein lipase is expressed in cultured Schwann cells and functions in lipid synthesis and utilization.
Huey PU, Marcell T, Owens GC, Etienne J, Eckel RH.
Department of Medicine, University of Colorado Health Sciences Center, 4200 E. 9th Avenue, Denver, CO 80262, USA.
We have previously demonstrated that lipoprotein lipase (LPL; triacylglycero-protein acylhydrolase, EC 3.1.1.34) is most likely expressed in the non-neuronal cells of the spinal cord, and glial cells may thus be the site of expression in the peripheral nervous system as well. We investigated the expression of LPL in cultured 1. 17 cells, an immortalized rat sciatic nerve Schwann cell line. The 1. 17 cells were shown to express LPL mRNA by reverse transcriptase-polymerase chain reaction analysis. The 1.17 Schwann cells demonstrated heparin-releasable lipolytic activity that was inhibited by the lipase inhibitor tetrahydrolipstatin in a dose-dependent manner. Preincubation of 1.17 cells with an anti-rat LPL antiserum reduced the heparin-releasable lipolytic activity to <10% of that measured in untreated cells. To investigate the role of LPL in Schwann cell lipid metabolism, 1.17 cells were incubated for up to 24 h with an emulsified [14C]triolein substrate and the incorporation of [14C]triolein radioactivity into various cellular lipids was examined in the presence of either anti-rat LPL antiserum or preimmune serum. Inhibiting LPL activity reduced the incorporation of 14C into cellular polar lipids, diacylglycerol, and cholesteryl esters by >80% at 2 and 6 h after addition of the radiolabeled substrate. At 24 h, radioactivity in diacylglycerol and cholesteryl esters was similar in cells treated with anti-LPL antiserum or preimmune serum, whereas 14C incorporation into polar lipids was still reduced by >60%. Separation of the polar lipids into individual lipid species revealed no specific changes in triolein-derived radioactivity incorporation across the phospholipid species examined. These results suggest that LPL-mediated hydrolysis of exogenous triacylglycerol is an important source of free fatty acids for the Schwann cell and thus may play a critical role in myelin biosynthesis in the peripheral nervous system.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9799799&dopt=Abstract
word match xenical online literature
Herbs and Pharmaceuticals Online ||
Hair Million herbal formula for hair loss and hair growth ||
Antibiotics and prescription medications online literature ||