Impaired cholesterol esterification in primary brain cultures of the lysosomal cholesterol storage disorder (LCSD) mouse mutant

Esterification of cholesterol was investigated in primary neuroglial cultures obtained from newborn lysosomal cholesterol storage disorder (LCSD) mouse mutants. An impairment in 3H-oleic acid incorporation into cholesteryl esters was demonstrated in cultures of homozygous LCSD brain. Primary cultures derived from other phenotypically normal pups of the carrier breeders esterified cholesterol at normal levels or at levels which were intermediary between normal and deficient indicating a phenotypic expression of the LCSD heterozygote genotype. These observations on LCSD mutant brain cells indicate that the defect in cholesterol esterification is closely related to the primary genetic defect and is expressed in neuroglial cells in culture.

Effect of insulin on low-density-lipoprotein metabolism in human lymphocytes in vitro

The metabolism of low-density lipoproteins (LDL) in vitro in the presence of insulin was studied in freshly isolated human peripheral-blood lymphocytes. Insulin appeared to decrease the binding affinity of 125I-LDL to its cell-surface receptor, without any change in apparent Vmax or in the number of LDL receptors. As a consequence, the absolute amounts of 125I-LDL internalized and degraded were lower in the presence of insulin than in its abscence, although the fraction of internalized 125I-LDL degraded in either instance was quite similar. 3-Hydroxy-3-methylglutaryl-CoA reductase activity, and hence cholesterol synthesis, were stimulated by insulin. This effect of insulin was independent of the inhibitory effect of LDL on cholesterol synthesis. At the same time, acid cholesterol esterase and acyl-CoA: cholesterol O-acetyltransferase activities were lower in cells incubated with insulin than in controls. The net effect of these metabolic alterations seems to be that cells accumulate greater quantities of free and esterified cholesterol when treated with insulin.

Plasma lipoprotein cholesterol in India in healthy persons and those with coronary heart disease

The plasma total cholesterol and lipoprotein cholesterol levels are presented for 186 healthy Indian subjects and 213 patients with coronary heart disease (CHD). Plasma lipid and lipoprotein concentrations vary with age. Higher total cholesterol and LDL cholesterol were noted in men compared with women. HDL cholesterol is highest in women in the age group 20-49 years. HDL cholesterol levels (negatively associated with CHD) are significantly higher in India compared with western countries. It is suggested that the high level of HDL cholesterol may be responsible for the relatively low incidence of CHD in India.