Serum Lipoprotein Metabolism Research Articles

Studies of hyperlipidemia in the HGH-deficient state

Plasma lipoproteins were analyzed in seven subjects with an isolated deficiency of human growth hormone (HGH). By plasma lipoprotein electrophoresis, each had a prominent beta band, and five also exhibited a strongly staining prebeta band. The prominent beta band was associated with elevation of plasma cholesterol and low density lipoprotein (LDL), while the increased prebeta band appeared to reflect the high levels of plasma triglycerides and very low density lipoproteins (VLDL). Glucose tolerance was abnormal in each subject, but basal plasma free fatty acid (FFA) and insulin concentrations were within the normal range. The data indicate that growth hormone deficiency is associated frequently with an abnormal serum lipoprotein pattern, and that, either directly or indirectly, the pituitary modulates serum lipoprotein metabolism. Cardiovascular disease was conspiciously absent in this group, a finding that will require further investigation.

Efcts of chronic ethanol feeding on serum lipoprotein metabolism in the rat.

In rats, chronic ethanol feeding was found to enhance the postprandial hyperlipemia and to increase the incorporation of dietary palmitic acid-(3)H and intravenously injected L-lysine-(14)C into serum lipoproteins. The main increases of total amount, labeling, and specific activity of lipid and protein occurred in the d < 1.019 lipoprotein fraction. Fat absorption and the clearance of injected chylomicrons were not affected by ethanol feeding. Blocking of lipoprotein and chylomicron removal with Triton did not prevent the action of ethanol on serum lipids, indicating that the ethanol effect is not likely due to defective removal of lipids from the circulation. Ethanol enhanced the incorporation of chylomicron fatty acids into newly synthetized very low density lipoproteins, as shown by an increased reappearance of the fatty acid label into the lipids of this fraction after injection of palmitate-(14)C/glycerol-(3)H doubly labeled chylomicrons. These results indicate that alcoholic hyperlipemia is due, at least in part, to an increase in newly synthetized lipoproteins. The hyperlipemia produced by ethanol was accompanied by hepatic steatosis. The simultaneous production of fatty liver and hyperlipemia makes it unlikely that defective lipoprotein synthesis or secretion is a primary mechanism for the pathogenesis of the alcoholic fatty liver.

Serum lipoprotein distribution, flotation rates and protein analysis.

AbstractFlotation rates of the major Sf 0舑12 lowdensity lipoprotein component in human serum may be calculated from ultracentrifuge data utilizing two computer programs. One program calculates a classical moving boundary uncorrected flotation rate by a best fit straight line for the points (1n xi, ३2ti). The other program permits erratum for concentration dependence and erratum to standard reference conditions. Preliminary application of these methods indicates significantly greater flotation rates in normal human females than in males for the 35舑49 year age group.The significance of interrelationships between the serum lipoprotein spectra, the serum lipids and the serum proteins is considered, resulting in the development of a revised method of measuring serum proteins by precision refractometry. The refractometric measurement is corrected in accordance with (any of various) lipid measurements in order to account for the contribution of lipoproteins to the total refractive increment. Such a technique, giving potentially a very accurate protein measurements, has application in screening studies involving abnormalities of both serum lipoprotein and serum protein metabolism.

Investigation of Serum Lipoprotein Metabolism in Man with I131-Labeled Triolein

T HE present investigation was undertaken to study the role of the several lipoprotein components of human serum in the transport of dietary fat. Labeled fatty acids in the form of I’s’ triolein were fed to normal subjects and patients with various blood lipid abnormalities in order to study the nature of these deviations from normal and their effects on lipid transport.