Jonathan P. Miller

Hypercholesteremia and atherosclerosis induced in rabbits by purified high fat rations devoid of cholesterol.

Summary Rabbits fed cholesterol-supplemented purified diets containing 20% of hydrogenated shortening or safflower oil showed lower plasma cholesterol levels on safflower oil diets, but only negligible differences between oils with respect to aortic atheroma production. Similar studies with cholesterol-free diets showed that rabbits on hydrogenated coconut oil are much more prone to hypercholesteremia than rabbits on safflower oil diets. In these latter studies aortic atheromatous lesions developed in all rabbits in 16 weeks on 20% of saturated fat as contrasted to negligible lesion production on 20% safflower oil.

Lipogenesis by adipose tissue, dietary effects.

Summary 1. The incorporation of C14-acetate into lipid and carbon dioxide by rat adipose tissue (in vitro) was investigated. This investigation concerned the effect of the nutritional status upon the lipogenic activity of adipose tissue. 2. Fasting was found to produce an increase in nitrogen concentration and a decrease in lipid concentration and lipogenic activity. 3. In normal rats lipogenic activity of the tissue was found to increase during recovery feeding following fasting. The increased activity was paralleled by increased nitrogen and glucose content of the tissue and by decreased lipid content. 4. Lipogenic activity of adipose tissue of rats could be made relatively constant by depletion of fat stores followed by recovery feeding.

Incorporation of radioacetate into lipid by adipose tissue in vitro: lipid characterization.

Abstract Normal minced rat epididymal adipose tissue incubated in vitro with 14 C- I -acetate incorporates the label almost entirely into the fatty acids of triglycerides with negligible incorporation into other lipid components (including cholesterol esters, cholesterol, non-esterived fatty acid, and phospholipid).

Lipogenesis by adipose tissue: Serum stimulating effects

Abstract The in vitro incorporation of [14C]acetate into lipid by rat adipose tissue was investigated. Rabbit, dog, rat and human sera were found to greatly enhance the incorporation of [14C]acetate into lipid by adipose tissue. Evidence is presented that the factors in serum responsible for its stimulatory effect upon lipogenesis are bicarbonate, glucose and free amino acids. The results indicate that those amino acids which enter the citric acid cycle during catabolism stimulate lipogenesis while other amino acids do not. Oxalacetate and succinate have a stimulatory effect upon lipogenesis while fumarate, malate, pyruvate, citrate and a-ketoglutarate have no such effect. Cyanide essentially abolished the lipogenic activity of adipose tissue while arsenate and fluoride reduced the activity approximately 50%. Malonate by itself had no appreciable effect upon lipogenic activity and caused an actual increased incorporation of the labeled acetate into carbon dioxide. In addition, malonate seemed to augment the lipogenesis-stimulating effect of succinate.

Regression Studies with Safflower Oil and Sitosterol in Rabbit Atherosclerosis

Hypercholesteremia with atherosclerosis was induced in male rabbits by feeding hydrogenated coconut oil as the only lipid in a purified diet. Replacing the hydrogenated coconut oil by safflower oil produccd a profound fall in plasma cholesterol in rabbits. Supplementing the safflower oil with βsitosterol at 3 per cent of the oil weight caused an even greater decrease in plasma cholesterol. Although in both cases the further development of aortic atheroma was arrested, there was no detectable regression of existing lesions, over 24 weeks. Hydrogenated coconut oil feeding produced high plasma and liver cholesterol levels in rabbits. When small amounts of safflower oil were fed in addition to the hydrogenated coconut oil, the elevation of plasma or liver cholesterol was much less.