The critical role of phosphatidylcholine and phosphatidylethanolamine metabolism in health and disease.

Animal lipoproteins: chemistry, structure, and comparative aspects.

[54] Thin-layer chromatography of lipids

Excerpt ▪Objective:To determine the effects of tamoxifen on risk factors for cardiovascular disease in disease-free postmenopausal women. ▪Design:Double-blind, placebo-controlled, randomized 2-year...

Effects of Tamoxifen on Cardiovascular Risk Factors in Postmenopausal Women

1. Large variations have been observed in the cholesteryl ester transfer activity of lipoprotein-free plasma isolated from 16 vertebrate species. 2. The different species have been arbitrarily divided into low, intermediate and high transfer activity groups, with man in the intermediate group. 3. Cholesteryl ester transfer activity did not correlate with the molar rate of cholesterol esterification in the plasma, nor with the concentration of cholesteryl ester in low density lipoproteins or high density lipoproteins. 4. It correlated positively and significantly with the concentration in very low density lipoproteins (r = 0.34, P = 0.014).

Differences in plasma cholesteryl ester transfer activity in sixteen vertebrate species

1. The lipid compositions of the low-density lipoproteins, the high-density lipoproteins and the ultracentrifugal residue of human serum are presented, with emphasis on certain lipoprotein classes and lipid components not previously described. 2. Except for the lipoproteins with the lowest and highest densities, there is a trend for stepwise successive increase or, respectively, decrease in the relative amounts of the main constituents of lipoproteins. 3. High-density lipoprotein-2 and high-density lipoprotein-3 have different amounts of certain lipids; high-density lipoprotein-2 has relatively more free cholesterol and sphingomyelin; high-density lipoprotein-3 has more free fatty acids, diglycerides and ceramide monohexosides. 4. All the lipoproteins contain hydrocarbons of the alkane series. The greatest amount, which averages 4.4% of total lipid extracted, is in the ultracentrifugal residue; n-alkanes comprise 18-50% of the hydrocarbons. 5. All the lipoproteins contain ceramide monohexosides. The highest relative contents of these glycolipids are in high-density lipoprotein-3 and in the ultracentrifugal residue. 6. The ultracentrifugal residue contains 55% of the total quantity of free fatty acids present in serum. The remaining free fatty acids are distributed among the other lipoprotein classes. 7. The choline-containing phospholipids (phosphatidylcholine, lysophosphatidylcholine and sphingomyelin) comprise about 90% of the phospholipids in all the lipoprotein classes except the low-density lipoprotein-2, which contains about 80% of these phospholipids. 8. The presence of a large amount of lysophosphatidylcholine in the ultracentrifugal residue and the successive decrease of sphingomyelin from the low-density lipoprotein-1 to the ultracentrifugal residue was confirmed. 9. The low-density lipoprotein-2 and the ultracentrifugal residue are characterized by relatively high contents of the lower glycerides.

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Valentina A. Fetzer

Papers

Lipid composition of human serum lipoproteins