References: Lecithin
Biochemistry. 1993 Jul 13;32(27):6965-73.
Phospholipase C-induced aggregation and fusion of cholesterol-lecithin small unilamellar vesicles.
Luk AS, Kaler EW, Lee SP.
Department of Chemical Engineering, University of Delaware, Newark 19716.
We have investigated the effects of the Ca(2+)-requiring enzyme phospholipase C on the stability of sonicated vesicles made with different molar ratios of cholesterol to lecithin. Vesicle aggregation is detected by following turbidity with time. Upon the addition of phospholipase C and after a short lag period, the turbidity of a vesicle dispersion increases continuously with time. The rate of increase of turbidity increases with both the enzyme-to-vesicle ratio and the cholesterol content of the vesicles. Vesicle fusion and leakage of contents are monitored by a contents-mixing fusion assay using 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS) and p-xylylenebis(pyridinium bromide) (DPX) as the fluorescence probes [Ellens, H., Bentz, J. & Szoka, F.C. (1985) Biochemistry 24, 3099-3106]. The results clearly show that phospholipase C induces vesicle fusion. The rate of vesicle fusion correlates with the enzyme-to-vesicle ratio but not with the cholesterol content of the membrane. Negligible aggregation and fusion of vesicles occurs when the experiment is repeated with buffer free of Ca2+. The membrane-destabilizing diacylglycerol, a product of lecithin hydrolysis by phospholipase C, is speculated to play a major role in driving the observed vesicle aggregation and fusion. The kinetics of vesicle aggregation and vesicle fusion can be predicted by linking Michaelis-Menten enzyme kinetics to a mass-action model.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8334126&dopt=Abstract lecithin
Bioconjug Chem. 1992 Jan-Feb;3(1):20-6.
Gadolinium complexes of [(myristoyloxy)propyl]diethylenetriaminetetraacetate: new lipophilic, fatty acyl conjugated NMR contrast agents.
Kim SK, Pohost GM, Elgavish GA.
Department of Medicine, University of Alabama, Birmingham 35294.
New lipophilic contrast agents, 1-[3'-(myristoyloxy)propyl]diethylenetriamine-1,4,7,7-tetraacetic acid (1MP-DTTA), 4-[3'-(myristoyloxy)propyl]diethylenetriamine-1,1,7,7-tetraacetic acid (4MP-DTTA), and 4-[3'-(myristoyloxy)propyl]-2,6-dioxodiethylenetriamine-1,1, 7, 7-tetraacetic acid (4MPD-DTTA), were prepared from either diethylenetriamine or 3-amino-1-propanol (overall yield 16-23%). Liposome-incorporated Gd complexes of ligands 1MP-DTTA, 4MP-DTTA, and 4MPD-DTTA were prepared by mixing GdCl3 and the prepared vesicles consisting of ligand, egg lecithin, and cholesterol (molar ratio 1.1:5.1) followed by further sonication, and their in vitro relaxivities were determined. The relaxivities of these agents were higher than those of the Gd3+ aquoion, Gd(EDTA), or Gd(DTPA) at both 0.23 and 0.47 T. Gd(4MPD-DTTA) displayed the highest relaxivities (24.0 +/- 0.4 and 34.7 +/- 0.4, at 0.23 and 0.47 T, respectively) among these new Gd complexes. The relaxivities of these three agents increased from the lower to the higher magnetic field, indicating a positive field dependence. Stability constants (log K) of Gd(1MP-DTTA), Gd(4MP-DTTA), and Gd(4MPD-DTTA) were found to be 18.2 +/- 0.2, 18.4 +/- 0.2, and 15.7 +/- 0.8, respectively. A lower limit of 0.3 mmol/kg was found for LD50 for these three agents.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1616946&dopt=Abstract lecithin
J Lipid Res. 1992 May;33(5):727-35.
Lecithin:cholesterol acyltransferase gene expression is regulated in a tissue-selective manner by fibrates.
Staels B, van Tol A, Skretting G, Auwerx J.
Department of Developmental Biology, Gasthuisberg, Katholieke Universiteit Leuven, Belgium.
Plasma lipoprotein metabolism is influenced by several factors that may act by regulating the expression of proteins involved in lipoprotein metabolism, such as lecithin:cholesterol acyltransferase (LCAT). We determined the influence of several hormones and hypolipidemic drugs on hepatic LCAT gene expression and plasma LCAT activity. Liver LCAT mRNA levels were resistant to regulation by the hormones ethinylestradiol, L-thyroxine, hydrocortisone, or by the hypolipidemic drugs probucol, simvastatin, and nicotinic acid. In contrast, hepatic LCAT mRNA levels decreased to 67%, 64%, and 46% of the control levels after treatment with the fibric acid derivatives clofibrate, gemfibrozil, and fenofibrate, respectively. Fenofibrate lowered liver LCAT mRNA levels in a dose-dependent manner, which was paralleled by a decrease in plasma LCAT activity to 54% of the controls at a dose of 0.5% (w/w) in rat chow. The decrease in liver LCAT mRNA levels was maximal after 1 day, whereas the fall in plasma LCAT activity trailed by 2 days. Cessation of treatment with fenofibrate restored liver LCAT mRNA levels to control levels within 1 week. The transcription rate of the LCAT gene decreased by 25% in nuclei isolated from fenofibrate-treated rat liver, thereby indicating that hepatic LCAT gene expression is, at least partly, regulated at a transcriptional level. In contrast to the liver, brain and testis LCAT mRNA levels remained constant after treatment with fenofibrate, indicating that fibrates regulate LCAT gene expression in a tissue-selective manner.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1619364&dopt=Abstract lecithin
Lecithin online literature || Lecithin online || Lecithin online || Lecithin online || Lecithin online || Lecithin online || Lecithin online || Lecithin online || Lecithin online
Buy Rx Online || Hair Million herbal formula for hair loss and hair growth || Hair Million, excellent herbal formula, wards off hair loss and promotes hair growth || Buy Tramadol || Dream Pharmaceuticals Online Pharmacy: Buy Rx Online || Lecithin product online guide ||