BIOLOGICAL AND MEDICAL RESEARCH DIVISION SEMIANNUAL REPORT, JULY THROUGH DECEMBER, 1959

Progress is reported on the following studies: the possible relationship between environmental Ra/sup 226/ and incidence of bone tumors in human populations; the incidence of tumors in mice exposed to chronic gamma irradiation; the effects of chronic gamma irradiation on histology of testes cells; the effects of periodic exposure to gamma radiation on the mortality of guinea pigs; determinations of the density of various mouse tissues; the synthesis of dimethyl formarmide (DMF) and uranyl nitrate-DMF; an investigation of the role of the small intestine in acute radiation death in mice following exposure to fast neutrons or gamma radiation; the effect of neutron dose on the incidence of mammary tumors and fertility of female rats and mice; measurements of Cs/sup 137/ in samples of tea and human milk made with a gamma spectrometer; the latency and growth of bone tumors induced by injected Sr/sup 90/ in two strains of mice; histopathologic changes in the skeleton of mice following injection of various doses of Ra/sup 226/ the development of mathematical models of cellular populations; reaction mechanisms in the response of chicks to radiation injuries; cell generation times in E. coli; the demonstration of infective organisms living in the cytoplasm of A. proteus; electron microscopic study of the fine structure of fat cells as related to structure; the effects of enzymes on induction of bacteriophage of E. coli; lipid metabolism and the isolation, fractionation, and analysis of cholesterol esters obtained during turnover studies; tracer studies on the role of urea in nitrogen metabolism using deuterium-labeled urea in which free energies of formation for deuterm-urea were determined; the participation of metal ions in transmethylation activity of enzymes in microorganisms; the effects of ultraviolet irradiation on yeast cells; the effects of thiol compounds on mitochondrial swelling; the effects of photoperiodism on flowering of xanthium; the effects of concentrations of 30 to 50% of deuterium oxide in drinking water on cells of male reproductive organs in mice and dogs and reproductive potential of male mice; the use of tritiated thymidine as a tracer in cell renewal in acute and chronic myelogenous leukemia; the loss of mutagenic potential in chemostat cultures of E. coli;, radioinduced recessive mutations in nince; the demonstration of a recessive mutation in Drosophila; the pathology of ectromelia (a virus disease) and pseudomonas infections in mice; the effects of x, gamma , and neutron irradiation on the formation of bacterial endotoxins in mice; the radioprotective effects of injected protoplasm in amoebas; the effects of chelating agents on the removal of monomeric and polymeric thorium in rats; the relationship of plutonium removal to tumor incidence in mice; the effects of chelating agents on the removal of monomeric and polymenic plutonium in mice; and the use-of tritiated thymidine to measure the growth of tumor metastases in mics. A list of publications during the period is included. (For preceding period see ANL-6200.) (C.H.