Douglas V. Frost

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.

Effects of Mineral Deficiencies on Amino Acid Utilization. Critical Role of Potassium and Phosphorus

Summary 1. Results of this study point to the critical role of potassium in amino acid utilization following protein depletion. Rats depleted only of protein failed completely, even when offered a complete source of amino acids, if at the same time potassium was withheld. If phosphorus was withheld during the repletion period, the rate of recovery was lessened, but complete failure and deaths did not result as with potassium deprivation. Deprivation of sodium, calcium or magnesium did not appear to have immediate limiting effects on the appetite of protein depleted rats for a complete amino acid source, or on their ability to recover lost weight. 2. Fourteen mg of potassium per rat day appeared to meet the requirement for this element. Addition of 10 mQv of potassium per liter to an intravenous protein hydrolysate appears to supply an effective, safe ratio of potassium to amino acid nitrogen.

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.

Studies on Amino Acid Inadequacy of Blood.

Summary(1) These studies further evaluate whole blood as sources of essential amino acids for protein depleted adult male rats. Human and canine blood again were rejected and failed to support repletion. Human blood supported rapid repletion when supplemented with 55 mg L-isoleucine and 15 mg DL-methionine per 120 mg of blood-N. Less than half these levels added to plasma supported repletion. Plasma alone permitted an intermediate rate of repletion. (2) Feeding normal dogs a non-protein diet and 150-375 mg N /kg/day as lyophilized human or dog blood did not increase the blood urea-N or NPN or produce negative N balance. Force-feeding 12-25 ml of citrated human blood increased blood urea-N of fasting rats. Supplementing the blood with isoleucine and methionine, however, did not reduce the blood urea-N. (3) Analysis of human blood, human plasma, and dog blood for 13 amino acids is reported.Summary (1) These studies further evaluate whole blood as sources of essential amino acids for protein depleted adult male rats. Human and canine blood again were rejected and failed to support repletion. Human blood supported rapid repletion when supplemented with 55 mg L-isoleucine and 15 mg DL-methionine per 120 mg of blood-N. Less than half these levels added to plasma supported repletion. Plasma alone permitted an intermediate rate of repletion. (2) Feeding normal dogs a non-protein diet and 150-375 mg N /kg/day as lyophilized human or dog blood did not increase the blood urea-N or NPN or produce negative N balance. Force-feeding 12-25 ml of citrated human blood increased blood urea-N of fasting rats. Supplementing the blood with isoleucine and methionine, however, did not reduce the blood urea-N. (3) Analysis of human blood, human plasma, and dog blood for 13 amino acids is reported.

Nutritive inadequacy of whole blood to support protein repletion.

Summary The inadequacy of whole human blood to serve as the sole dietary source of amino acids for repletion in the protein-depleted rat is demonstrated. Fortification of blood with isoleucine and methionine, the 2 indispensable amino acids in which blood is most deficient, largely corrects this nutritive inadequacy.