Electrophoresis and Monomolecular Layer Studies with Serum Lipoproteins

Abstract

Abstract The chemical analysis of the lipids in serum or plasma yields data for total lipids, phosphatides, total and esterified cholesterol, and by subtraction, for neutral fat. Zone electrophoresis, for which experimental details are given, shows the distribution of the serum lipids between α-globulin, -globulin, and a fraction which does not move in the electric field. Values are given for normal man, monkey, dog, and rabbit. Their distinctive patterns are correlated with differences in the propensity of these species to develop atherosclerosis. Combined studies of the lipid partition and the electrophoretic profile were carried out on patients with disturbed lipid metabolism, particularly myxedema, nephrosis of various etiology, and idiopathic hyper-lipemia and hypercholesteremia. The lactescence of lipemic sera is ascribed primarily to increases of the neutral fat and corresponding increases of the electroneutral fraction of the lipoprotein electropherogram. In the Kimmeistiel-Wilson syndrome, the nephrotic syndrome in dis.betes, and in idiopathic hypercholesteremia, where the cholesterol level is increased but the neutral fat level normal, the sera usually remain clear. In animal experiments the destruction of thyroid tissue and, in particular, the feeding of cholesterol induces hypercholesteremia and hyper-phosphatidemia in dog and rabbit. The signs of lipemia are further enhanced by the simultaneous administration of cortisone, when the total lipids in the rabbit run sometimes above 7 per cent of the serum. This experimental condition is associated with severe atherosclerotic lesions. A model for lipoproteins is provided by the reaction between serum albumin and fatty acids, the latter in the form of monomolecular layers. The technic is described. The specificity of the ripping-off reaction and its parallelism with the dyestuff affinity of serum albumin are illustrated and discussed. The application of the reaction to the study of the "albumin defect" in infectious, rheumatic, and malignant disease is suggested.