Small Low-density Lipoprotein Cholesterol Concentration Research Articles

Small Low-Density Lipoprotein Cholesterol Concentration is a Determinant of Endothelial Dysfunction by Peripheral Artery Tonometry in Men

Endothelial dysfunction is an initial step in the progression of atherosclerosis. Precise measurements of lipoprotein subclass distribution by high-performance liquid chromatography (HPLC) have been established. Here, we investigated the potential associations between lipoprotein subclass cholesterol concentrations and endothelial dysfunction evaluated by digital reactive hyperemia peripheral arterial tonometry (PAT). We recruited 120 apparently healthy Japanese men. Endothelial function was assessed by digital reactive hyperemia PAT, expressed as the logarithmic-scaled reactive hyperemia index (RHI). Plasma cholesterol concentrations in lipoproteins and their subclasses were determined by HPLC with gel permeation columns. RHI was inversely correlated with age (r=-0.258, p=0.004), followed by LDL cholesterol (r=-0.236, p=0.010) and small LDL cholesterol (r=-0.223, p=0.014). In addition, RHI was significantly inversely associated with heart rate, hemoglobin A1c, total cholesterol, medium LDL cholesterol, apolipoprotein B100, and non-HDL cholesterol. In stepwise multiple regression analysis, age (β=-0.266, p=0.024), small LDL cholesterol (β=-0.213, p=0.015), and heart rate (β=-0.183, p=0.036) were found to be independent determinants of RHI (adjusted R(2) =0.132, p<0.001). Small LDL cholesterol concentration was an important, independent determinant of endothelial dysfunction in men.

Circulating malondialdehyde-modified low-density lipoprotein is strongly associated with very small low-density lipoprotein cholesterol concentrations in healthy men

Background Despite the importance of oxidized LDL and small LDL particles as atherogenic lipoproteins, the relationship between oxidized LDL and the distributions of size subclasses of lipoproteins is not fully proved. We investigated the relationship of circulating malondialdehyde-modified (MDA)-LDL, an oxidized form of LDL, and lipoprotein subclasses in healthy men. Methods The study group consisted of a total of 170 healthy Japanese men (55 ± 9 y). Plasma cholesterol concentrations in major lipoproteins and their subclasses were determined by HPLC with gel permeation columns. Results In univariate analysis, body mass index, waist circumference, blood pressure, white blood cell count, C-reactive protein, uric acid, fasting insulin, HOMA-IR, total cholesterol, triglycerides, each VLDL subclass cholesterol, each LDL subclass cholesterol, small HDL cholesterol, and very small HDL cholesterol were positively correlated with MDA-LDL, whereas adiponectin and large HDL cholesterol were inversely correlated with MDA-LDL. In stepwise multiple regression analysis, very small LDL cholesterol, medium VLDL cholesterol, very small HDL cholesterol, small HDL cholesterol, and systolic blood pressure were identified as independent determinants of MDA-LDL ( R 2 = 0.718, p < 0.0001). Conclusions Circulating MDA-LDL concentrations are strongly associated with very small LDL cholesterol concentrations in healthy men. HDL size heterogeneity has a biphasic effect on MDA-LDL.

Short-term changes in lipoprotein subclasses and C-reactive protein levels of hypertriglyceridemic adults on low-carbohydrate and low-fat diets

Diets designed to promote weight loss and improve atherogenic lipid profiles traditionally include a reduction in total fat and, in particular, saturated fats. This study was designed to test the efficacy of a low-fat diet vs a carbohydrate (CHO)-restricted (low-CHO) diet in hypertriglyceridemic patients on lipid profile, weight loss, high-sensitivity C-reactive protein (hs-CRP), and satiety. Twenty-eight hypertriglyceridemic subjects (based on fasting triacylglycerol [TG] levels exceeding 1.69 mmol/L) were randomized to either the low-CHO or low-fat diet for 8 weeks. Fasting bloods were acquired at weeks 0 and 8 and analyzed for lipids and hs-CRP. Body weight and other anthropometric measures were also obtained. Three random 24-hour food recalls were used to assess compliance during the trial and 2 recalls before randomization to permit individualized dietary education. A significant time-by-treatment interaction was observed (P = .045), wherein the small low-density lipoprotein cholesterol concentrations were reduced by 46% in the low-CHO-assigned subjects and increased by 36% for those assigned the low-fat plan. The observed decrease in TG (18%) among low-CHO subjects, in contrast to the 4% increase for low-fat group, was not significant, nor were there significant differences in hs-CRP, overall dietary compliance, satiety, or the magnitude of body weight loss between groups (low-CHO group, -3.8% vs low-fat group, -1.6%). Favorable reductions in small low-density lipoprotein concentrations after 8 weeks suggest that a moderately restricted carbohydrate diet (20% CHO as energy) can promote a less atherogenic lipid profile when compared to the low-fat diet.