In order to examine the relationship between certain risk factors for atherosclerosis and family history of myocardial infarction, we compared a group of children (n=51) whose parents had survived myocardial infarction (n=34) with a control group of children (n=90) with a negative family history of atherosclerosis (62 parents). The study revealed a surprising fact that 26.7 % of control children had hypercholesterolaemia compared to 15.7 % incidence in "risk" children. "Risk" children differed from the controls most in the apo-A-l levels and a higher risk index expressed by the proportion of apo-B:apo-A-l (1.22, 1.34 g/1, p=0.001, 0.58, 0.46, p=0.05, respectively). Since the most frequent primary hyperlipoproteinaemia in myocardial infarction families was familial combined hyperlipoproteinaemia, we assume that this condition may be presented in affected children by an unfavourable proportion of apolipoproteins of the lipoprotein classes.
The Prague Hereditary Hypercholesterolaemic (PHHC) rat is a strain of the Wistar rat very sensitive to dietary cholesterol.The dynamics of changes in serum and liver lipids and lecithin : cholesterol acyltransferase (LCAT) were studied immediatelly after the switch to a high cholesterol diet. Immediate cumulation of free and esterified cholesterol in the liver after the increase in alimentary cholesterol intake is supposed to be the regulating step leading to a subsequent increase in serum cholesterol concentration. Activity of LCAT was negatively correlated to the concentration of free cholesterol in the liver, very early after the cholesterol diet was introduced, a possibility of a down regulation of enzyme synthesis similarly to the regulation of synthesis of cholesterol in hepatocytes was observed.
The frequencies of the alleles of Xbal polymorphism in the apolipoprotein B gene were determined in two groups of children, 82 with high (HCG) and 86 with low (LCG) cholesterol levels. A slightly higher incidence of the X2X2 genotype in HCG was found, but the differences were not statistically significant. No relations were found between the Xbal polymorphic site and the levels of serum lipids and lipoproteins. Common Xbal polymorphism in the apolipoprotein B gene does not determine significantly the plasma cholesterol levels in childhood.