Composition of low-density lipoprotein in children with hyperlipoproteinaemia

Relationship between cholesteryl ester transfer protein and LDL heterogeneity in familial hypercholesterolemia

Small, dense LDL particles have been associated with an increased risk of coronary artery disease, and cholesteryl ester transfer protein (CETP) has been suggested to play a role in LDL particle remodeling. We examined the relationship between LDL heterogeneity and plasma CETP mass in familial hypercholesterolemia (FH). LDL particles were characterized by polyacrylamide gradient gel electrophoresis in a total of 259 FH heterozygotes and 208 nonFH controls. CETP mass was measured by enzyme-linked immunosorbent assay in a subgroup of 240 participants, which included 120 FH patients matched with 120 controls. As compared with controls, FH subjects had an 11% higher CETP mass. Moreover, LDL-peak particle diameter (LDL-PPD) was significantly smaller in FH heterozygotes than in controls (258.1 +/- 4.8 vs. 259.2 +/- 4.1 A; P = 0.01) after adjustment for covariates. There was also an inverse relationship between LDL-PPD and CETP mass (R = -0.15; P = 0.02), and this relationship was abolished by adjustment for the FH/control status, indicating that LDL-PPD changes in FH are mediated, at least in part, by an increase in plasma CETP mass concentrations. These results suggest that increased plasma CETP mass concentrations could lead to significant LDL particle remodeling in FH heterozygotes and could contribute to the pathogenesis of atherosclerosis.

Increase of serum lipids and serum lipoproteins in girls under therapy with estrogen and norethisteron for height reduction

The effect of a combined treatment with ethinyl estradiol and norethisteron for height reduction on serum lipids and lipoproteins was investigated in 23 excessively tall girls (greater than 97th percentile). Serum cholesterol, triglycerides, HDL-C and LDL-C were determined before and 3, 6, 9 and 12 months after the onset and 3 to 12 months after cessation of therapy. Treatment with ethinyl estradiol and norethisteron resulted in significant (p less than 0.01) mean increases in serum cholesterol, triglycerides, HDL-C, and LDL-C of 20.6%, 95.5%, 23.6%, and 22.2% above pretreatment values, respectively. This increase occurred during the first 3 months of therapy and thereafter no further significant change was observed. After cessation of therapy elevated levels returned to pretreatment levels within 3 to 12 months in all but two patients. The results obtained suggest an influence of ethinyl estradiol and norethisteron on serum lipids and lipoproteins. Whether these reversible changes of serum lipids and lipoproteins are associated with an increased risk for developing atherosclerosis has to be evaluated in long term investigations.

A study of the structural heterogeneity of low-density lipoproteins in two patients homozygous for familial hypercholesterolaemia, one of phenotype E2/2

The structural heterogeneity of the low-density lipoproteins (d 1.019-1.063 g ml-1) in two female patients homozygous for familial hypercholesterolaemia, one of phenotype E2/2, has been evaluated using a new ultracentrifugal density gradient procedure. The mass distribution, chemical composition, particle size and heterogeneity, hydrated density and apolipoprotein content of 16 LDL subfractions were determined. By gradient gel electrophoresis, the lighter LDL subfractions (d 1.016-1.037 g ml-1) displayed a single particle species which progressively diminished in size from 24.8 to 22.0 nm with increase in density. By contrast, subfractions of higher density (d greater than 1.037 g ml-1) exhibited two LDL particle species of distinct size; one component decreased in size from 21.8 to 20.4 nm with increase in density, while the second maintained an essentially constant diameter (between 22.5 and 23.5 nm) across these LDL subfractions. Immunoblotting with anti-apo-B100 of LDL subspecies separated by gradient gel electrophoresis showed all particles to contain apo-B100. However, dot-blots and immunoblotting with a monoclonal antibody to lipoprotein (a) (Lp(a)) revealed that the LDL particle subspecies of greatest diameter (22.5-23.5 nm) present in the denser subfractions (d greater than 1.037 g ml-1) also contained the Lp(a) antigen. These findings, taken together with the high plasma Lp(a) levels (greater than 60 mg dl-1) in our patients, raise the possibility that Lp(a) may contribute in a significant manner to the atherogenic process in homozygous familial hypercholesterolaemia.

Apolipoproteins and lipoproteins in children with type I diabetes: relation to glycosylated serum protein and HbA1

Serum levels of cholesterol (C), triglycerides (TG), lipoprotein-C and apolipoproteins (apo) A-I, A-II and B were measured in 30 children with type I diabetes mellitus (16 boys, 14 girls, aged 11-14 years) and in 26 healthy controls (15 boys, 11 girls, aged 10-13 years). For 19 diabetics controls matched for age, sex and relative body weight were selected. The diabetic patients were considered to be in fair metabolic control according to HbA1 levels and glycosylated serum protein concentrations. Mean serum apo A-I, A-II and B, C, TG, low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) did not differ significantly between diabetic nondiabetic children. Very low density lipoprotein cholesterol (VLDL-C) was significantly higher in diabetic children than in controls. Serum C and LDL-C levels showed close univariate linear correlations with glycosylated serum protein (LDL-C: r = 0.53, p less than 0.01, C: r = 0.58, p less than 0.01) in diabetics. The ratio LDL/HDL-C was significantly correlated to HbA1 levels (r = 0.47, p less than 0.01). By canonical and multiple linear correlation analysis significant relations of a selected set of variables concerning the control and therapy of diabetes (serum glucose, HbA1, glycosylated serum protein, insulin dose) with a set of lipoprotein variables (C, TG, VLDL-C, HDL-C, LDL-C, apo A-I, A-II, B) could be demonstrated. From these data we conclude that significant relations between atherogenic serum lipids and lipoproteins (C, LDL-C) and the degree of metabolic control exist in diabetic children, even in the absence of marked dyslipoproteinemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum apolipoproteins and lipoprotein (a) during the first week of life

The levels of apolipoproteins, A-I, A-II, B and E, lipoprotein (a) and of total cholesterol and triglycerides were determined in cord serum and in capillary serum at the fifth day of life in a group of 44 term newborns. Additionally, cord serum lipoproteins were estimated. Sera from 26 healthy adults were studied for comparison. The concentrations of lipids and lipoproteins in cord serum were diminished as compared to adult levels. The occurrence of lipoprotein (a) in cord serum in concentrations significantly lower than in adults could be established. Serum apolipoproteins A-I, A-II and B were significantly lower at birth than in the adult, whereas apolipoprotein E levels did not differ from adult concentrations. During the first five days apolipoprotein B levels more than doubled, apolipoprotein A-I increased moderately and apolipoprotein E rose slightly. In contrast, serum lipoprotein (a) and apolipoprotein A-II did not change significantly. Unlike serum cholesterol, the levels of apolipoproteins B and E at day five were significantly correlated to those measured at birth in the same infants. The changes of the apolipoprotein pattern during the first week of life reflect the evolution of the lipid transport system of the newborn and may be related to the increasing utilisation of fat and to hormonal factors.

Reversible abnormalities of low density lipoprotein composition in familial hypercholesterolaemia

Low density lipoprotein (LDL) composition was analysed in twenty-one patients with familial hypercholesterolaemia, including six homozygotes. By comparison with nineteen controls the patients' LDL had an increased ratio of cholesterol:phospholipid and a decreased ratio of lecithin:sphingomyelin; these changes were more marked in homozygotes than in heterozygotes. Treatment of sevel patients with plasma exchange temporarily resulted in near-normalization of the composition of their LDL. These results suggest that abnormalities of LDL composition in familial hypercholesterolaemia are secondary to hypocatabolism of LDL, which prolongs the half-life of LDL and thus increases the mean age of the population of particles circulating in plasma.

Abnormal low density lipoproteins in children with familial hypercholesterolemia--effect of polyanion exchange resins

In 20 children and adolescents with familial Type II a hyperlipoproteinemia, serum lipids and lipoproteins were examined before and during treatment with polyanion exchange resins. The composition of LDL was compared to that of helthy siblings. The patients were given Colestyramine (0.6 g/kg body weight) and Colestipol (0.5 g/kg body weight) in a cross-over study for 8 weeks each, after they had been under dietary treatment for at least 12 months. In 6 children, drug treatment had to be stopped due to side-effects. The most common complaints were gastrointestinal discomfort and constipation. Cholesterol, triglycerides and phopholipids were measured in whole serum and cholesterol, triglycerides and Apolipoprotein-B in isolated lipoprotein fractions after ultracentrifugation. Apo-B was determined by radial immunodiffusion. The Apo-B: cholesterol ratio in whole serum and in the LDL fraction was identical in the patients and in the controls. The LDL triglyceride: Apo-B ratio, however, was about 50% lower in the patients. This abnormal LDL composition was not altered by therapy with polyanion exchange resins. HDL cholesterol levels were significantly lower in the patients than in healthy children, and remained low during therapy. The decrease of total and LDL cholesterol (25%) and Apo-B (20%) was similar under both Colestipol and Colestyramine. Triglycerides and phospholipids showed no significant changes in therapy.