Plasma Cholesterol Esterification in Normal and Hyperlipoproteinemic Subjects

Abstract

Plasma lipid values and the initial rates of plasma cholesterol esterification in vitro have been studied in seven normal subjects and in 34 patients with primary hyperlipoproteinemia of the different types.Compared with that of normal subjects, the mean rate of cholesterol esterification (nanomoles cholesterol esterified per hour per milliliter of plasma) is significantly increased in type II (p < 0.05), whereas the mean increases noted in types III, IV, and V are not significant. The mean relative rate (percentage cholesterol esterified per hour) is decreased in type III (p < 0.05).The correlations between plasma lipid values and cholesterol esterification have been calculated in each type as well as in normal and hyperlipoproteinemic subjects taken as a group (total group). In the total group, plasma cholesterol esterification (nanomoles per hour per milliliter) is weakly correlated with unesterified cholesterol (r = 0.384), with triglycerides (r = 0.416), and with the ratio of triglycerides to total cholesterol (r = 0.439). Only in the group of normal subjects is the rate of cholesterol esterification strongly correlated with triglycerides (r = 0.896) and with the ratio of triglycerides to total cholesterol (r = 0.885). Finally, there is a strong negative correlation (r = −0.792, p < 0.001) between the rate of cholesterol esterification expressed in the percentage of cholesterol esterified per hour and the ponderal index in the total group. This negative correlation indicates a positive correlation between cholesterol esterification and obesity. In all subjects, we have also found that negative or positive caloric balances caused the rates of cholesterol esterification to be, respectively, decreased or increased as compared with the mean of the group considered.