Alteration of resistance of the rat to tuberculosis when maintained on an atherogenic diet

Albino rats maintained for 50 to 60 days on rations containing cholesterol, sodium cholate, and thiouracil were found to be highly susceptible to the lethal effects of infection with Mycobacterium tuberculosis. Maximum loss of resistance occurred only when all three components were present in a single ration. A lesser degree of susceptibility resulted from the deletion of one or more of the factors from the diet. Animals maintained on control rations never died of the infection. Histopathological studies of stained sections of tissues of infected animals revealed that the reaction of the host to the bacillus was more extensive and less well contained in animals fed the complete atherogenic ration than in the controls.

Effects of saturated and unsaturated fat feeding on experimental thromboatherosclerosis

Intra-aortic insertion of magnesium-aluminum-zinc wire was used to induce experimental aortic thrombosclerosis in rabbits fed kennel chow and in rabbits fed chow supplemented with cholesterol, with and without additions of saturated or unsaturated fat. In the absence of cholesterol supplement, no spontaneous atherosclerosis developed and no excess lipid appeared in the thrombosclerotic plaque, regardless of supplementations with saturated or unsaturated fat. In the presence of cholesterol supplement, both spontaneous atherosclerosis and thromboatherosclerosis were noted. Additional supplementations with saturated or unsaturated fat did not ameliorate either lesion. Rabbits ingesting cholesterol plus unsaturated fat exhibited no less hypercholesteremia, spontaneous atherosclerosis, and thromboatherosclerosis than did rabbits on any other regimen. The results are discussed with reference to the effect of oral unsaturated fat on bile acid and cholesterol within the intestinal lumen.

Pancreatectomy in rats: onset of metabolic changes in liver, adipose, and diaphragm

The time of onset of metabolic alterations in utilization of C14-labeled glucose and acetate by liver and adipose tissue, and in uptake of glucose by diaphragm was studied in "totally" depancreatized rats, a preparation in which severe manifestations of diabetes develop rapidly. The earliest changes were observed in glucose utilization by liver and adipose tissue. Two hours after pancreatectomy, conversion of glucose carbon to a) fatty acids, glycogen, and CO2 by liver slices and b) fatty acids and CO2 by adipose tissue was depressed. Defective utilization of acetate appeared earlier in adipose tissue than in liver. A decrease in the liver's capacity to convert acetate carbon to fatty acids developed some time between 4 and 14 hr after pancreatectomy. In adipose tissue this occurred between 2 and 4 hr. Defective uptake of glucose by diaphragm was observed later after pancreatectomy, some time between 4 and 14 hr. The results are discussed from the standpoint of the nature of metabolic lesions in the diabetic liver and of whether insulin has a direct or indirect action on hepatic tissue.