Low-density Lipoprotein In Type Research Articles

Characterization with zonal ultracentrifugation of low-density lipoproteins in type V hyperlipoproteinemia

Low-density lipoproteins (density = 1.019−1.063 g/ml) were isolated in 10 subjects with type V hyperlipoproteinemia by ultracentrifugation in a zonal rotor under rate flotation conditions. Plasma LDL concentrations in these patients were extremely reduced, as well as being heterogeneous, and two different subclasses consisting of LDL 2 (density = 1.019−1.045 g/ml) and LDL 3 (density = 1.045−1.063 g/ml) were observed. LDL 2 and LDL 3 have similar electrophoretic mobilities in β position in agarose gel, and their diameters, calculated from gel filtration studies, were inversely proportional to their densities. LDL 2 and LDL 3 have a mean hydrated density of 1.034 and 1.054 g/ml, respectively. In comparison with normal LDL 2, the LDL 2 and LDL 3 of hypertriglyceridemic subjects are particularly rich in triacylglycerols and poor in cholesteryl esters and free cholesterol, while they have an increasing amount of proteins. The protein moiety is composed almost exclusively of apolipoprotein B-100 in IDL, LDL 2 and LDL 3; in addition, IDL also contain apolipoprotein C peptides. This characterization of LDL heterogeneity in type V hyperlipoproteinemia should be considered in interpreting kinetic data in human normal and pathological lipid metabolism and in evaluating the atherogenic risk of hypertriglyceridemia.

Dietary effects on very low-density lipoproteins in type 2 (non-insulin-dependent) diabetes mellitus.

To evaluate possible influences of dietary intervention on the composition of very low-density lipoproteins (VLDL), ten subjects with Type 2 (non-insulin dependent) diabetes mellitus received a hypocaloric regimen. Fifteen healthy subjects served as controls. Ultracentrifuged VLDL were analysed as cholesterol, triglycerides, apolipoprotein B (apo B), and the soluble apolipoproteins C and E (polyacrylamide gel electrophoresis in urea and densitometry) before the study, after 2 weeks and then after 3 months. Compared with the control subjects, the content of cholesterol and apo E in the VLDL was elevated in the diabetic subjects, while the area ratio of apo C-II to apo C-III1 was lowered. After diet the reduction in VLDL was accompanied by compositional changes: a decrease of the cholesterol/triglyceride ratio and of the apo E/apo C area ratio. The apo C-II/apo C-III1 area ratio remained unaffected. We conclude that one beneficial effect of therapeutic intervention in diabetes may lie in lowering the level of possibly atherogenic VLDL-components.

Effects of bezafibrate on the composition of very low density lipoproteins in type IV hyperlipoproteinemia

As compared to normolipoproteinemic controls 10 male subjects with primary type IV hyperlipoproteinemia had higher apolipoprotein E and lower apolipoprotein C-II concentrations in the very low density lipoprotein (VLDL) fraction. After 8 weeks of treatment with 0.6. g/day bezafibrate, cholesterol and triglyceride in the serum and VLDL were significantly lower. The decrease of VLDL lipids was accompanied by a significant decrease of the apolipoproteins and of the lipid/protein ratio in VLDL. The analysis of the soluble VLDL apolipoproteins revealed a decrease of apo E and an increase of apo C1 and apo C2, resulting in a decrease of the apo E/apo C ratio.

The influence of clofibrate on lipid and protein components of very low density lipoproteins in type IV hyperlipoproteinaemia

After 30 days of clofibrate administration to 11 patients with type IV hyperlipoproteinemia, a significant fall was observed in serum triglyceride and cholesterol levels. In the VLDL fraction the concentrations of triglycerides, cholesterol and apo B were significantly decreased. The apo CII/apo CIII 1, ratio was raised. Cholesterol concentration changes in LDL and HDL fractions were not significant.

Zero electrophoretic mobility of very low density lipoproteins in type III hyperlipidemic patients during treatment

In some cases of type III hyperlipoproteinemia reduction of lipid levels by diet and/or drugs results in a complete loss of mobility of the VLDL fraction on paper electrophoresis.