Distribution of low density lipoprotein subclasses in Macedonian children.

BACKGROUND: Current reports claim that small and dense LDL particles are more atherogenic than larger LDL particles. There are many studies presenting LDL subclass distribution in adults, but there is not enough data regarding children in the literature on this problem. The aim of our study was to examine LDL subclass distribution in healthy children in the Republic of Macedonia. MATERIALS/METHODS: Plasma LDL subclasses in 100 children aged 9-18 years were analyzed using non-denaturing polyacrilamide gradient (3-31%) gel electrophoresis. Conventional plasma lipid and apoprotein parameters thought to be related to LDL size were determined as well. RESULTS: The results obtained showed the prevalence of large LDL subclasses (phenotype A) in 89% of the children, whereas small LDL subclasses (phenotype B) were observed in 11%. The mean LDL size was 26.37 +/- 0.68 nm, and there was no difference between gender groups. No association was noted between LDL size and plasma lipid and apoprotein levels, age, or BMI. CONCLUSIONS: LDL size and distribution is not gender- or age-dependent, or influenced by plasma lipid and apoprotein concentrations in childhood. This suggests that analysis of LDL subclass phenotype may provide better information on the risk of atherosclerosis development in adulthood.

Apoprotein(a) phenotypes and plasma lipoprotein(a) concentration in patients with diabetes mellitus.

OBJECTIVES: To determine whether apo(a) isoforms and plasma Lp(a) concentrations in association with some lipid parameters increase the relative risk for the development of atherosclerosis in patients with diabetes mellitus (IDDM and NIDDM). DESIGN AND METHODS: Apo (a) isoforms, Lp(a) and plasma lipids were determined in 40 IDDM and 65 NIDDM patients and in 182 healthy individuals. Apo(a) isoforms were separated by 3 to 15% gradient SDS-PAGE followed by immunoblotting. RESULTS: Logistical analysis showed that: Lp(a) levels >30 mg/dL (RR = 0.25, p < 0.000001; RR = 0.18, p < 0.00002), HTA (RR = 0.212, p < 0.00001; RR = 0.30, p < 0.00001), LMW-S1 apo(a) isoform (RR = 6.86, p < 0.0131; RR = 7.04, p < 0.0057) play a significant role in aterogenecity in both groups of patients with DM (IDDM and NIDDM). The 6.50-fold increase in risk was found in NIDDM patients with high Lp(a) levels (>30 mg/dL) and plasma total/HDL cholesterol ratio (4.5-5.8). CONCLUSION: Elevated Lp(a) levels, LMW S1 apo(a) isoform, HTA and combination of increased Lp(a) levels and total/HDL cholesterol ratio increase the risk for the development of atherosclerosis in patients with DM (IDDM and NIDDM).

Frequency distribution of apoprotein(a) isoforms in patients with diabetes mellitus and healthy subjects.

AIM: To determine the frequency distribution of apoprotein(a) isoforms in patients with insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus and healthy subjects. METHOD: We separated and visualized 5 apo(a) isoforms in 40 patients with IDDM (12 men aged 48.00-/+4.59 and 28 women aged 52.37-/+8.21), 65 patients with NIDDM (26 men aged 61.88-/+9.25 and 39 women aged 60.15-/+7.98), and 182 healthy subjects, using 3-15% gradient sodium dodecyl sulfate polyacrylamide gel electrophoresis, followed by immunoblotting. RESULTS: The frequency distribution of apo(a) isoforms was very similar in patients with diabetes mellitus and the control group. Atherogenic low molecular weight (LMW) S1 apo(a) isoform was more frequent in patients with IDDM (7.5%) and NIDDM (6.15%) than in the control group (0.78%). LMW S1 apo(a) isoform in patients with IDDM (relative risk [RR], 6.86; 95% confidence interval [CI], 1.19-25.21; p<0.001) and patients with NIDDM (RR, 7.04; 95% CI, 1.40-35.40; p=0.0057) as well as high molecular weight >S4 apo(a) isoform in patients with NIDDM (RR, 2.39; 95% CI, 1.28-5.21; p=0.0067) significantly increased the risk for the development of atherosclerosis. Mean molecular weight of S3, S1, and B apo(a) isoforms was higher in patients with IDDM and NIDDM than in the healthy subjects carriers of the same isoforms, but this difference was not statistically significant. We estimated high inverse statistical correlation between apo(a) size (kDa) and plasma lipoprotein(a) concentration in all study groups, patients with IDDM (p<0.001), patients with NIDDM (p<0.001), and healthy subjects (p<0.01). CONCLUSION: Not only the increased plasma Lp(a) levels, but also apoprotein(a) isoforms may play an important role as a risk factor for the development of atherosclerosis in patients with diabetes mellitus.

LDL and HDL subclass distribution in patients with end-stage renal diseases.

OBJECTIVES: To examine the alterations in LDL and HDL subclass distribution in ESRD patients compared with a control group and to investigate the relationship of LDL particle size to the other plasma lipoproteins levels. DESIGN AND METHODS: Plasma lipids, LDL and HDL subclasses were determined in 63 hemodialysis patients (HD), 42 predialysis patients and 345 control subjects. Lipoprotein subclasses were separated by polyacrylamide 3 to 31% gradient gel electrophoresis. RESULTS: In predialysis group, 88% subjects had small LDL particles compared with 58.5% of hemodialysis patients and 16.5% of control subjects. Mean LDL size particle diameter was significantly smaller in HD and predialysis patients in comparison with controls (p < 0,0005, p < 0,0001; respectively). Significant inverse correlation between LDL particle size and triglyceride level was observed for both patient groups. Decreased levels of the largest HDL2b subclass was found in both predialysis (16.5%) and in HD patients (30%) as compared with controls (50%), and increased levels of the small HDL3a subclass was found only in predialysis group (21%) in comparison with controls (4.5%). CONCLUSIONS: Alterations in LDL and HDL subclass distribution toward smaller particles is the main lipid abnormality associated with atherogensis found in ESRD. ESRD is associated with reduced levels of HDL2b subclass and increased levels of HDL3c subclass, which occurs in coronary artery disease (CAD) as well.

Low density lipoprotein particle size phenotyping in healthy persons and patients with myocardial infarction.

AIM: To determine distribution, size, and phenotype of low density lipoprotein (LDL) subclasses and examine the influence of plasma lipid concentrations on lipoprotein particle size in both healthy population and patients with myocardial infarction. METHOD: Nondenaturing gradient (3-31%) gel electrophoresis for lipoprotein separation was used to determine the distribution and size of LDL subclasses in 132 patients with myocardial infarction and 334 healthy control subjects. RESULTS: Large LDL subclasses (LDL1, LDL2, phenotype A) were dominant in 88.5% of the healthy population, whereas in most patients with myocardial infarction (81%) the dominant subclasses were LDL3 and LDL4 (phenotype B). Only 19% of the patients belonged to the phenotype A (LDL1 and LDL2). Mean LDL subclass size (nm) was significantly smaller in patients with myocardial infarction than in controls (24.381.07 nm vs 25.940.89 nm; p<0.001). In both groups, LDL size was independent of LDL plasma cholesterol but associated with high triglyceride plasma concentrations. CONCLUSION: Coronary artery disease is associated with the predominance of small LDL particles and high plasma triglyceride concentrations. The risk of development of cardiovascular disease can be assessed more accurately by determining lipoprotein subclasses.

Gradient gel electrophoretic separation of LDL and HDL subclasses on BioRad Mini Protean II and size phenotyping in healthy Macedonians.

BACKGROUND: Lipoprotein subclass determinations provide a more detailed reflection of lipoprotein metabolism and an accurate prediction for risk of cardiovascular disease. Gradient gel electrophoresis for lipoprotein separation on Pharmacia electrophoretic apparatus has been most commonly used for many years. METHODS: In this paper, we describe a new method for separating LDL and HDL subclasses by nondenaturing polyacrylamide gradient (3-31%) gel electrophoresis, using BioRad Mini Protean II electrophoretic cells. RESULTS: The mean particle diameters of cholesterol-stained LDL and HDL lipoproteins were estimated after calibrating the gels with size standards, using fractional absorbance profiles. For the first time in the Republic of Macedonia, lipoprotein distribution and size phenotyping were studied in 345 healthy individuals. Large LDL subclasses (phenotype A) were dominant in 88.5% of the population, whereas small LDL subclasses (phenotype B) were dominant in 11.5%. The mean dominant LDL size was 26.08+/-0.8 nm. Five HDL subclasses were separated on the same gels, and HDL2b and HDL2a (larger) were dominant in healthy Macedonians. CONCLUSION: Antiatherogenic, larger LDL and HDL particles are most commonly found in healthy populations in the Republic of Macedonia.