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Endogenous Lipids (endogenous + lipid)
Selected AbstractsDocosahexaenoic acid stabilizes soluble amyloid-, protofibrils and sustains amyloid-,-induced neurotoxicity in vitroFEBS JOURNAL, Issue 4 2007Ann-Sofi Johansson Enrichment of diet and culture media with the polyunsaturated fatty acid docosahexaenoic acid has been found to reduce the amyloid burden in mice and lower amyloid-, (A,) levels in both mice and cultured cells. However, the direct interaction of polyunsaturated fatty acids, such as docosahexaenoic acid, with A,, and their effect on A, aggregation has not been explored in detail. Therefore, we have investigated the effect of docosahexaenoic acid, arachidonic acid and the saturated fatty acid arachidic acid on monomer oligomerization into protofibrils and protofibril fibrillization into fibrils in vitro, using size exclusion chromatography. The polyunsaturated fatty acids docosahexaenoic acid and arachidonic acid at micellar concentrations stabilized soluble A,42 wild-type protofibrils, thereby hindering their conversion to insoluble fibrils. As a consequence, docosahexaenoic acid sustained amyloid-,-induced toxicity in PC12 cells over time, whereas A, without docosahexaenoic acid stabilization resulted in reduced toxicity, as A, formed fibrils. Arachidic acid had no effect on A, aggregation, and neither of the fatty acids had any protofibril-stabilizing effect on A,42 harboring the Arctic mutation (A,E22G). Consequently, A,Arctic-induced toxicity could not be sustained using docosahexaenoic acid. These results provide new insights into the toxicity of different A, aggregates and how endogenous lipids can affect A, aggregation. [source] Changes in phosphatidylinositol and phosphatidylinositol monophosphate kinase activities during the induction of somatic embryogenesis in Coffea arabicaPHYSIOLOGIA PLANTARUM, Issue 2 2003Marķa Julissa Ek-Ramos Evidence was obtained for the presence of phosphatidylinositol (PIK) and phosphatidylinositol monophosphate kinase (PIPK) at different developmental stages during somatic embryogenesis in Coffea arabica L. by in vitro phosphorylation of endogenous lipids in the presence of [,- 32P]ATP followed by thin-layer chromatography. The results indicate the existence of a relationship between the development stages that were analysed and the kinases found. In cells without differentiated structures (EC, embryogenic calli) phosphatidylinositol kinase and phosphatidylinositol monophosphate 5-kinase (EC 2.7.1.68) activities were present. These activities increased significantly in the first differentiated stage (PREG, preglobular structures) and decreased as the development stages advanced. Phosphatidylinositol monophosphate (PIP) formation decreased from the globular (GLO) to the cotyledonary (COT) stage. The PIP fraction contained both isomers, PI 3-P and PI 4-P. This demonstrates PI3K (EC 2.7.1.137) and PI4K (EC 2.7.1.67) activity during somatic embryogenesis in Coffea arabica L. When wortmannin, an inhibitor of PI3K and PI4K activities, was included in an in vitro assay, a dose-dependent inhibition of the formation of both isomers was observed. The addition of wortmannin to the induction medium during the PREG stage reduced the number of normal embryos. Our results suggest that PI and PIP kinases and the formation of certain phosphoinositides may play roles in the regulation of somatic embryo development in Coffea arabica L. [source] Phosphonium labeling for increasing metabolomic coverage of neutral lipids using electrospray ionization mass spectrometry,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2009Hin-Koon Woo Mass spectrometry has become an indispensable tool for the global study of metabolites (metabolomics), primarily using electrospray ionization mass spectrometry (ESI-MS). However, many important classes of molecules such as neutral lipids do not ionize well by ESI and go undetected. Chemical derivatization of metabolites can enhance ionization for increased sensitivity and metabolomic coverage. Here we describe the use of tris(2,4,6,-trimethoxyphenyl)phosphonium acetic acid (TMPP-AA) to improve liquid chromatography (LC)/ESI-MS detection of hydroxylated metabolites (i.e. lipids) from serum extracts. Cholesterol which is not normally detected from serum using ESI is observed with attomole sensitivity. This approach was applied to identify four endogenous lipids (hexadecanoyl-sn-glycerol, dihydrotachysterol, octadecanol, and alpha-tocopherol) from human serum. Overall, this approach extends the types of metabolites which can be detected using standard ESI-MS instrumentation and demonstrates the potential for targeted metabolomics analysis. Published in 2009 by John Wiley & Sons, Ltd. [source] Reducing glycerophosphocholine lipid matrix interference effects in biological fluid assays by using high-turbulence liquid chromatographyRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2008Lihong Du Matrix interferences can severely affect quantitative assays of biological samples when electrospray ionization (ESI) is employed with liquid chromatography/tandem mass spectrometry (LC/MS/MS). A major source of matrix interferences for plasma sample analyses is the presence of glycerophosphocholine (GPCho) lipids. The efficiency of online high-turbulence liquid chromatography (HTLC) extraction for eliminating these lipids is evaluated and the interfering effects of endogenous lipids on human plasma assays are measured for pharmaceutical compounds having a wide variety of chemical properties. It is found that GPCho lipids, represented by 16:0, 18:1 and 18:0 LPC (lysophosphatidylcholine) and 16:0-18:2 PC, cause variations for hydrophobic compound analyses even when optimal online HTLC extraction conditions are employed. The efficiency for lipid removal depends on the organic content of the transfer solvent, but turbulent flow loading has no significant effect. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||