References: Lecithin
Mol Vis. 1997 Oct 24;3:11.
Analysis of esterification of retinoids in the retinal pigmented epithelium of the Mitf-vit (vitiligo) mutant mouse.
Evans BL, Smith SB.
Department of Cellular Biology and Anatomy, Medical College of Georgia, Augusta, Georgia 30912-2000, USA.
PURPOSE: Mice homozygous for the vitiligo mutation of the microphthalmia (Mitf) gene have a retinal degeneration characterized by slow loss of photoreceptor cells and compromised retinal pigment epithelial (RPE) structure and function. The levels of retinyl esters, which are essential for generation of 11-cis-retinaldehyde for the formation of rhodopsin, were reported previously to be elevated by 6 weeks postnatally in the RPE of vitiligo mutant mice. The purpose of the present study was to determine whether this elevation was due to increased activity of lecithin:retinol acyl transferase (LRAT) the enzyme that converts all-trans-retinol to retinyl esters. METHODS: Retinoids extracted from the RPE and neural retina of mutant and normal mice ages 2, 4, 6 and 8 weeks were analyzed by reversed-phase HPLC. The esterification capacity of the RPE to convert 3H-retinol to 3H-retinyl ester was determined by HPLC in mutant and normal mice at 3 and 9 weeks. RESULTS: Retinyl ester levels were elevated significantly in the mutant RPE as early as postnatal week 2 and were four-fold greater by 8 weeks. The esterification assay indicated no significant differences between mutants and controls at 3 weeks. At 9 weeks, the esterification activity of the mutant RPE was significantly reduced compared to controls rather than elevated. CONCLUSIONS: The data suggest that the accumulation of retinyl esters is not due to increased LRAT activity. Alternative explanations for the retinyl ester accumulation are discussed.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9383334&dopt=Abstract lecithin
J Biol Chem. 1992 Dec 5;267(34):24356-62.
Complexation with heparin prevents adhesion between fibrin-coated surfaces.
Retzinger GS, Chandler LJ, Cook BC.
Department of Pathology, Medical College of Wisconsin, Milwaukee 53226.
Heparin, in Langmuirian fashion, binds stoichiometrically with high affinity, Kd approximately 100 nM, to both fibrinogen and fibrin adsorbed as monomolecular films to lecithin-coated, microscopic, polystyrene-divinylbenzene beads. Complex formation inhibits aggregation of fibrin-coated beads, and it also results in dissociation of preformed aggregates of fibrin-coated beads. These phenomena are not caused by desorption of fibrin(ogen), indirect inhibition of thrombin activity, or mere electrostatic repulsion of charged particles. Instead, these data are consistent with the proposal that the complexed heparin interferes directly with dimer formation between fibrin molecules adsorbed to colliding beads. We describe these phenomena and their application to the development of sensitive analytical methods for quantitating heparin. Based on these observations, we also propose a role for endogenous heparin in the physiologic regulation of fibrin-mediated adhesion of surfaces.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1447186&dopt=Abstract lecithin
Zhonghua Bing Li Xue Za Zhi. 1995 Feb;24(1):8-10.
[Apolipoprotein A-IV and transportation of cholesterol from smooth muscle cells in experimental hyperlipidemia]
[Article in Chinese]
Wang Z, She M, Xu M.
Department of Pathology, Chinese Academy of Medical Sciences and School of Basic Medicine, Beijing.
The effects of apolipoprotein (apo) A-IV and apoA-IV/phosphatidylcholine (PC) liposome on cholesterol efflux from the smooth muscle cells originating from the aorta of hypercholesterolemic rabbit model and control rabbits, and on the activation of lecithin cholesterol acyltransferase (LCAT) were studied respectively. Both apoA-IV/PC and apoA-I/PC liposomes have similar efficiency as the HDL's, i.e. a strong ability to clear intracellular cholesterol and the ability to activate LCAT. There were no differences noticed on the clearance ability between apoA-IV and apoA-I or between apoA-IV/PC and apoA-I/PC liposomes. These results suggest that apoA-IV may play an important role in the process of reverse cholesterol transport and apoA-IV/PC liposome may be effectively used instead of natural HDL to prevent the development of atherosclerosis.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7781120&dopt=Abstract lecithin
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