Analysis of human plasma phosphatides by paper chromatography

Phosphatase content of rat calvaria after in vivo administration of vitamin D3 metabolites

The effects of acute or chronic administration of small doses (130 pmol) of 25-hydroxycholecalciferol, 24,25-dihydroxycholecalciferol, and 1,25-dihydroxycholecalciferol on rat calvaria acid and alkaline phosphatase activities were investigated in weanling male albino Wistar rats raised on a vitamin D-deficient, low-calcium diet. The results indicate that each of these active metabolites has a different effect on calvarial phosphatase activities. 25-hydroxycholecalciferol causes a significant increase, and 24,25-dihydroxycholecalciferol a decrease in the enzymatic activity. In animals treated with 1,25-dihydroxycholecalciferol these activities are lower after one injection, but after seven daily doses they are not different from those of ethanol-injected control rats. The observed changes do not seem to be related to changes in serum calcium and/or phosphorus concentrations.

Recombination of integral and peripheral protein fractions from human red cell membrane with homologous lipids

Integral and peripheral protein fractions from human red cells membranes were recombined with a total red cell lipid extract and with homologous lipids in varying mixtures, by dialysis from 2-chlorethanol solutions. The 2 protein fractions were compared for lipid binding capacity and for selectivity towards individual lipids.

Plasma concentrations of lysolecithin and other phospholipids in the healthy population and in men suffering from atherosclerotic diseases

The concentrations of individual phospholipids and of cholesterol have been determined in plasma samples taken from 77 apparently healthy individuals, and from 76 male patients presenting with atherosclerotic diseases. Significant differences in the relative and absolute concentrations of lysolecithin were found between different populations. In healthy individuals the plasma levels of lysolecithin were lower in women than in men and lower in the younger age groups studied. The relative and absolute concentrations of plasma lysolecithin were lower in men suffering from chronic ischaemic heart disease and peripheral arterial disease when compared with age-matched healthy male subjects. The lowest levels of plasma lysolecthin were, however, associated with patients suffering from acute myocardial infarction or acute myocardial ischaemia studied within 48 hr of the onset of chest pain. In a further study, significantly decreased relative concentrations of lysolecithin were found in blood platelets and erythrocytes as well as in plasma of patients suffering from chronic ischaemic heart disease. The results are discussed in terms of a possible thrombo-protective role for plasma lysolecithin in man.

Dietary linoleic acid and the plasma phospholipids of the rabbit

1. Groups of rabbits were given diets containing different proportions of butterfat and maize oil. After the animals had been given the experimental diets for 40 weeks the plasma phospho- lipids were fractionated and the fatty acid composition of each fraction was determined.

2. Phosphatidyl choline and lysophosphatidyl choline accounted for about 75 and 12% respectively of the total plasma phospholipids: phosphatidyl ethanolamine, sphingomyelin and phosphatidyl serine accounted for only about 5.3, 5.0 and 2.6% respectively. Changes in the linoleic acid content of the diet had little effect on the relative proportions of the individual plasma phospholipids, but there was an over-all decrease in the concentration of total phospholipids in the plasma as the linoleic acid content of the diet was increased from 0.25 to 10.6%.

3. When the diet contained 0.25 % linoleic acid, the linoleic acid:oleic acid ratio in the phosphatidyl choline (1.3) was similar to that in the phosphatidyl ethanolamine (1.2), but as the linoleic acid content of the diet was increased to 10.6% the linoleic acid:oleic acid ratio in the phosphatidyl choline increased to 48, whereas that in the phosphatidyl ethanolamine increased only to 2.2. Increases in the linoleic acid content of the diet resulted also in increases in the linoleic acid:oleic acid ratios in the phosphatidyl serine, lysophosphatidyl choline and sp hingomyelin.

4. When the linoleic acid content of the diet was increased, the stearic acid:palmitic acid ratio in the phosphatidyl choline increased, whereas it decreased in the phosphatidyl ethanol- amine and remained relatively unaltered in the phosphatidyl serine. The stearic acid contents of the lysophosphatidyl choline and sphingomyelin were unaltered by dietary treatments, but the palmitic acid content of these two phospholipids decreased as the linoleic acid content of the diet increased.

5. The results are discussed in terms of the metabolic relationships that exist between the various phospholipids.

Phospholipids of the liver in children suffering from protein-calorie undernutrition

1. Thirty-nine children suffering from protein–calorie undernutrition were classified into nineteen with kwashiorkor, twelve with marasmus and eight with nutritional oedema according to history, physical findings and laboratory investigations. Liver biopsy samples from these patients were extracted with lipid solvents and the phospholipids were fractionated into phosphatidylcholine, ethanolamine and serine, and sphingomyelin.

2. The total liver phospholipids were found to be reduced in kwashiorkor and the reduction was mainly in the phosphatidyl ethanolamine fraction. The decrease in phosphatidyl ethanolamine was probably due to an observed reduction in free serine content. The ethanolamine phosphatase activity of the liver was found to be high in kwashiorkor.