The rate of degradation of oxidatively modified low density lipoprotein (Ox-LDL) by human endothelial cells was similar to that of unmodified low density lipoprotein (LDL), and was approximately 2-fold greater than the rate of degradation of acetylated LDL (Ac-LDL). While LDL and Ac-LDL both stimulated cholesterol esterification in endothelial cells, Ox-LDL inhibited cholesterol esterification ...

Animals fed cholesterol accumulate several types of cholesterol-rich lipoproteins in their plasma and ultimately develop cholesteryl ester deposition in tissue macrophages. Previous studies in the cholesterol-fed dog have shown that one class of cholesterol-rich lipoproteins, P-migrating very low density lipoproteins (P-VLDI,, density < 1.006 g/ml), possesses a unique ability to produce cellula...

The plasma lipoproteins are continuously remodeled during their transit through the plasma compartment, owing to the action of lipid metabolizing enzymes and lipid transfer processes. These activities have a major effect on the composition, size, and concentration of the lipoproteins. Lipid transfer processes involving neutral lipids and phospholipids are mediated by specialized plasma proteins...

our previous experiments indicated that smooth muscle cells (SMC) in neointima of injured rabbit aorta (a) acquire the capacity to produce PGI2 and (b) have increased lysosomal CE hydrolytic (acid cholesteryl ester hydrolase [ACEH])activity. Using cultured SMC from rabbit thoracic aorta, we demonstrated that PGI2, 6-keto-PGF1,, and 6-keto-PGE, enhanced ACEH activity fourfold. No significant eff...

Cellular cholesteryl ester metabolism is regulated largely by the balance between intracellular esterification catalyzed by acyl-CoA:cholesterol acyltransferase and cholesteryl ester hydrolysis catalyzed by the cholesteryl ester hydrolases. The hydrolases include both cytosolic and membrane-associated activities; acidic and neutral activities have been described in both compartments. Esterifica...

Alloxan-diabetic rabbits develop a pronounced hypercholesterolemia and hypertriglyceridemia in response to cholesterol feeding. Despite higher levels of plasma cholesterol, these animals have much less atherosclerosis than cholesterol-fed nondiabetics. To determine whether this effect is due to properties of the lipoproteins, we compared chemical, physical, and metabolic characteristics of a ve...

Beta very low density lipoproteins (beta-VLDL) from cholesterol-fed animals from patients with Type III hyperlipoproteinemia are internalized by a receptor-mediated process in mouse macrophages. Once internalized, the cholesteryl esters of beta-VLDL are hydrolyzed in lysosomes, and the released cholesterol is re-esterified, resulting in a massive accumulation of cholesteryl esters. In the prese...

The effect of two different levels of dietary cholesterol (0.16 mg/Kcal and 0.79 mg/cal) on the composition of thoracic lymph duct lipoproteins was studied in two species of nonhuman primates, Ceropithecus aethiops (African green monkey) and Macaca fascicularis (cynomolgus monkey). Diet was infused intraduodenally at a constant rate to facilitate comparisons among animals. The higher level of d...

Steroid hormones are synthesized using cholesterol as precursor, with a substantial portion supplied by the selective uptake of lipoprotein-derived cholesteryl esters. Adrenals express a high level of neutral cholesteryl ester hydrolase activity, and recently hormone-sensitive lipase (HSL) was shown to be responsible for most adrenal neutral cholesteryl ester hydrolase activity. To determine th...

Acetone powders of a 20,000g pellet fraction from spinach leaves (Spinacia oleracea L.) synthesized [4-(14)C]cholesteryl esters when incubated with [4-(14)C]cholesterol. The reaction was inhibited by digitonin. There was a reciprocal relationship between the decline of label in cholesterol and its incorporation into cholesteryl ester, indicating that free cholesterol was the direct precursor fo...