Studies on Arteriosclerosis : I. Determination of Serum β-lipoprotein by the Dextran Sulfate Method and its Clinical Significance

Abstract

Various investigations have been performed about the pathogenesis of atherosclerosis, but no clear explanation has been presented so far. It has been suggested that atherosclerosis in man is often due to disturbed lipid metabolism, and in recent years β-lipoprotein, among the lipid fractions, has come to receive much attention for its role in the pathogenesis of atherosclerosis. The present paper describes a simple method of determining β-lipoprotein with dextran sulfate as reagent, and suggests that the level of β-lipoprotein determined by it may serve as an index of the severity of the disease. Method 1) The human subjects consisted of 465 normal persons, 114 patients with coronary insufficiency, 157 with hypertension, 42 with cerebrovascular lesions, 41 with diabetes mellitus, 66 with nephritis, and 29 with nephrotic syndrone. 2) In the animal experiment 28 male rabbits weighing 2 to 3 kg each were em-ployed. They were divided into two groups, one group being fed for a period of 90 days, and the other for 20 days. Each group was further subdivided into two, one subgroup being placed on an ordinary diet and the other on a lanolin-containing diet. 3) The serum β-lipoprotein level was determined with dextran sulfate as reagent. The turbidity produced when the reagent was added to the serum was measured with a Beckmann colorimeter, and the β-lipoprotein content was obtained by referring to a calibration curve prepared with standard solutions of known concentrations. In measuring the amounts of the other lipid fractions, modified Zak-Henly's method was employed for total cholesterol, alkali titration after extraction by Bloor and katsura-Hatakeyamas method for total fatty acid, modified Zilveramith's method for phospholipid, Bragdon's method for neutral fat, polarography after extraction by Grossman's method for non-esterified fatty acid. Results The coefficients of correlation between β-lipoprotein and total cholesterol, free cholesterol, total fatty acid, non-esterified fatty acid, phospholipid, and neutral fat were 0.73, 0.72, 0.75, 0.45, 0.52 and 0.59 respectively, showing pretty good positive correlation in every case.