Cultured cells possess high-affinity binding sites (receptors) for high density lipoprotein (HDL) that appear to mediate removal of excess intracellular cholesterol from cells. To examine the role of intact HDL apoproteins in receptor-mediated cholesterol removal, HDL3 apoproteins were digested with the proteolytic enzymes trypsin and pronase, and the residual particles were used in sterol effl...

Previously we have shown that peroraly administered silymarin, a mixture of antioxidant flavonolignans from medicinal plant Silybum marianum (L.), prevents both the accumulation of exogenous cholesterol in the liver and the development of diet-induced hypercholesterolemia in rat1, 2. The silymarin-induced decrease of plasma cholesterol has been associated with a decrease in apo B containing lip...

Optimization of sample pre-treatment. Complete removal of cellular and further solid sample constituents, precipitation and removal of proteins, precipitation and removal of cholesterol from the blood sample and quantitative extraction of the analytes tryptophan, phenol, p-cresol and cholic acid in the diluted blood plasma phase. Step III: Combination and conversion of both isocratic HPLC/DAD/M...

OBJECTIVE ATP-binding cassette transporter A1 (ABCA1) is thought to lipidate apolipoprotein A-I (apoA-I) at the plasma membrane, with endosomal cholesterol contributing as substrate. The mechanisms of ABCA1 surface delivery are not well understood. We have shown that Rab8 regulates endosomal cholesterol removal to apoA-I in human fibroblasts. Here, we investigated whether Rab8 plays a role in A...

Three membrane properties were strikingly affected when the cholesterol of human erythrocytes, normally approximately 0.8 mol/mol of phospholipid (i.e. C/P approximately 0.8), was altered by equilibration with phospholipid dispersions of an appropriate cholesterol content. 1) While the sterol in intact red cell membranes of C/P less than or equal to 0.8 was resistant to cholesterol oxidase dige...

The importance of cholesterol for endocytosis has been investigated in HEp-2 and other cell lines by using methyl-beta-cyclodextrin (MbetaCD) to selectively extract cholesterol from the plasma membrane. MbetaCD treatment strongly inhibited endocytosis of transferrin and EGF, whereas endocytosis of ricin was less affected. The inhibition of transferrin endocytosis was completely reversible. On r...

It is widely believed that high density lipoprotein (HDL) protects against cardiovascular disease by removing excess cholesterol from cells of the artery wall. Recent cell culture studies have provided evidence that a major pathway for removing cholesterol and phospholipids from cells is mediated by the direct interactions of HDL apolipoproteins (apo) with plasma membrane domains. These interac...