The fate of bacteria within phagocytic cells. I. The degradation of isotopically labeled bacteria by polymorphonuclear leucocytes and macrophages

The intraleucocytic fate of a variety of P³²- and C¹⁴-labeled bacteria has been studied in both polymorphonuclear leucocytes and macrophages. Both cell types brought about extensive degradation of bacterial lipids, nucleic acids, and proteins. Intracellular breakdown was primarily dependant upon the composition of the ingested particle rather than on the type or source of the phagocyte. Evidence is presented for the reincorporation of bacterial constituents into leucocyte lipid. More than 50 per cent of the acid-soluble degradation products of P³²-labeled bacteria appear as inorganic phosphate. Bacterial RNA is degraded more readily than DNA. Following phagocytosis, labeled bacteria lose their pool of small molecular weight intermediates. This is followed by the degradation of acid-insoluble constituents. The majority of bacterial breakdown products are then excreted by the leucocyte and appear in the medium. Heat-killed bacteria were more readily broken down than viable organisms. Only small amounts of C¹⁴-labeled bacteria were completely oxidized by leucocytic enzymes to C¹⁴O₂. Acid extracts of polymorphonuclear leucocyte granules, which were highly bactericidal, liberated the acid-soluble constituents of labeled bacteria but did not significantly degrade bacterial macromolecules.

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.