Low density lipoprotein size in relation to carotid intima-media thickness in coronary artery disease.

OBJECTIVE: With increasing interest in the role of non-traditional lipid risk factors in coronary artery disease, we undertook this study to relate LDL subclass size and carotid intima-media thickness of the common carotid artery in coronary artery disease patients. METHODS: The study was conducted in 106 patients during their first visit (study group I) and after 12 months (study group II). Intima-media thickness of the common carotid artery was determined using B-mode ultrasound. Separation of LDL subclasses was preformed by 3-31 % polyacrylamide gradient gel electrophoresis. RESULTS: LDL3 was the dominant subclass in both study groups, but there was statistically significant difference in the distribution of dominant LDL subclasses (p<0.01). The mean carotid intima- media thickness was significantly increased (p<0.001) in coronary artery disease patients after 12 months period. There was significant negative correlation between intima-media thickness and LDL size in both study groups (p<0.05). Intima-media thickness was not significantly correlated with plasma lipid concentrations. Multiple regression analyses show that strongest independent predictor of the intima-media thickness variation was diastolic blood pressure, followed by LDL size and age, and accounted for 29 % of the observed variability in intima-media thickness. CONCLUSION: LDL particle size is independently associated with carotid intima-media thickness in coronary artery disease patients with normal levels of traditional lipid risk. These results imply that small, dense LDL subclasses are an important indicator for assessing atherosclerosis and its progression (Tab. 4, Ref. 39).

Low density lipoprotein subclass distribution in children with diabetes mellitus.

BACKGROUND: The role of small dense low-density lipoprotein (sLDL) subclasses in atherosclerosis has been demonstrated in many studies. Among other metabolic changes, the alteration in LDL lipoprotein subclass distribution and size has been proved in diabetic adults. Because there is not enough literature data presenting LDL subclass distribution in childhood, the aim of this study was to examine LDL subclass profile in diabetic children compared with healthy control. MATERIAL AND METHODS: Plasma LDL subclasses in 30 children with type I diabetes mellitus and 100 healthy children aged 9-18 years were analyzed using non-denaturing polyacrilamide gradient (3-31%) gel electrophoresis. Conventional plasma lipid and apoprotein parameters which are thought to affect LDL size were determined as well. RESULTS: Analysis of LDL phenotype has shown that a great percentage of healthy children (89%) yield bigger LDL1 with LDL2 subclasses being dominant (phenotype A), whereas 11 % of the children belong to phenotype B characterized by the presence of small, atherogenic LDL3 and LDL4 subclasses. In diabetic children despite no significant differences in their plasma lipid profile when compared with healthy control, the frequency of LDL phenotype B was increased (86.7 %), and the mean LDL diameter was smaller (p < 0.0001). LDL size was inversely correlated with plasma levels of triglycerides, and positively correlated with plasma HDL cholesterol and BMI. CONCLUSION: Although plasma levels for lipid and apoprotein were within the normal range, the increased frequency of LDL phenotype B confirms a grater risk of atherosclerosis development in children with diabetes mellitus. LDL size measurement may potentially help to assess cardiovascular risk and adapt the treatment goals thereafter (Tab. 3, Ref. 38). Full Text (Free, PDF) www.bmj.sk.

Lipoprotein (a) and apolipoprotein (a) phenotypes in healthy Macedonian children.

BACKGROUND: Plasma levels of lipoprotein(a) [Lp(a)] are determined largely by genetic variation in the gene encoding apolipoprotein(a) [apo(a)], the unique protein component of Lp(a). High plasma levels of Lp(a) increase the risk of premature atherosclerosis. However, the association of apo(a) phenotypes with the development of these diseases remains largely unexplored. OBJECTIVES: Determination of Lp(a) levels and apo(a) isoforms (phenotypes) in 100 (51 boys, 49 girls) Macedonian healthy children aged 9-18. METHODS: We used 3-15 % gradient SDS-PAGE for separation of apo(a) isoforms. According to the different apo(a) electrophoretic mobilities, Apo(a) was classified into five single and respective double-band phenotypes. RESULTS: Each individual expressed a single (homozygotic), double-band (heterozygotic) or no band (null phenotype). The apo(a) phenotype frequencies revealed that the frequency of single-band phenotype expression (64 %) was higher than that of double bands (32 %) and that the frequency of phenotypes representative of low molecular weight was very low (4%). The most frequent phenotype was S4 (42.65%). The distribution of plasma Lp(a) levels was skewed, with the highest frequencies at low levels. The mean Lp(a) concentration was 11.95 (SD of 5.98 and median of 9.62 mg/dL). We did not find differences in the mean and median plasma Lp(a) levels between boys and girls (p > 0.05). A strong inverse relationship was found between the apparent molecular weight of apo(a) phenotypes and plasma Lp(a) concentration (r = -0.4257). CONCLUSIONS: Determination of Lp(a) levels and apo(a) phenotypes in children, may help in preventing and reducing the risk of atherosclerotic development (Tab. 6, Ref 32). Full Text (Free, PDF) www.bmj.sk.