Search

The use of activated alumina for the removal of selenium from heap leach detoxification solutions was studied at a laboratory scale. Three aluminas were studied: one unmodified and two chemically modified to function better in a basic pH range. The best performer, Discovery Chemicals DD-6, readily accumulated selenium oxyanions. Furthermore, it could be stripped of selenium and several metals by a mild caustic solution (pH 11.5 to 12.0) and regenerated for further use. Tests using −600 +300-μm (28 x 48 mesh) material indicated that 96% could be removed from solution, and tests using −1.18-mm +600-μm (14 x 28 mesh) material indicated that 91 % could be removed. Flow rates were approximately 58 mL/min. The bed volumes were about 0.8 L. However, soluble silica can accumulate on the activated alumina and subsequently interfere with its regeneration. Therefore, it should be removed from the detox solution prior to use of the adsorbent.

Rats were injected with 3H-thymidine and three days later exposed to 500 r and 1000 r whole-body x-irradiation. The animals were sacrificed at various times after exposure and autoradiographs were prepared from spleen, thymus, testis, intestine, adrenals, liver, kidney and muscle. Autoradiographs were also prepared from a group of non-irradiated rats at different intervals after injection of 3H-thymidine. Extensive cell-destruction with subsequent phagocytosis of labelled nuclear debris by macrophages was observed in spleen and thymus. Cell and DNA-replacement was inhibited in the intestine, and the maturation of spermatogonia to primary spermatocytes seemed to be delayed in the testes of x-irradiated rats. Other organs of x-irradiated rats showed no significant alterations in their labelling pattern.

Rats were injected with sulphate-35S and/or glucose-U-14C, were exposed to x-rays two or three days later, and were sacrificed two or three days after exposure. Sulphate and hexosamine were isolated from mucopolysaccharides of bone and skin, and hexosamine was also isolated from soluble and insoluble collagen of skin and from total collagen of bone. On the basis of the changes in the specific activity of these compounds after irradiation, it was concluded that the replacement of mucopolysaccharides is partially inhibited after x-irradiation. The changes in the specific activity of hexosamine associated with collagen were not marked, but exhibited a trend similar to that observed previously in amino-acid residues of collagen from irradiated rats.

1. The degree of incorporation of PBG-3,5-14C into haemin was determined in bone-marrow homogenates of rabbits after 600 r, 800 r or 1000 r of whole-body x-irradiation.2. The time-periods studied after exposure to x-rays ranged from 30 min to 48 days.3. In parallel with the capacity of bone-marrow to synthesize haemin, DNA-concentration and haemin-concentration were determined.4. The capacity of bone-marrow homogenate to synthesize haemin increased significantly on the first, seventh and fourteenth day after exposure to 600 r and on the seventh and fourteenth day after exposure to 800 or 1000 r.5. After exposure to 800 r, similar patterns of radiation-induced changes were found when PBG or DAL were used as precursors. These patterns differed markedly from those observed when glycine was used as a precursor.

Rats were injected with proline-U-14C and exposed to total-body x-irradiation at various time-intervals thereafter. Proline was isolated from the soluble protein and elastin fractions of various organs and its specific activity determined. In most organs an increase in specific activity of proline of these two protein fractions was observed after irradiation. This was interpreted to mean either a lowered metabolic replacement or a loss of certain components from these protein fractions after irradiation. It is suggested that the decrease in specific activity observed in the spleen is correlated to changes in the cell-population in this organ after irradiation.

1. Creatine-2-14C was injected into rats at different times after x- or sham-irradiation.2. Muscle creatine and phosphocreatine, as well as creatine from blood, kidney and urine, were isolated and their respective specific activities determined. Urinary creatinine was also isolated and its 14C-activity determined.3. Coincident with the maximal excretion of creatine, the specific activities of muscle creatine and phosphocreatine decreased after x-irradiation.4. Immediately after injecting the x-irradiated rats with creatine-2-14C, the specific activity of urinary creatine increased, whereas that of creatinine decreased, but at a somewhat later time.5. It is postulated that defective utilization of creatine by muscle constitutes the cause of radiation-induced creatinuria.

1. An attempt was made to determine the source of excess 14C -labelled glycine and phenylalanine observed in ' free ' metabolic pools of rats loaded with glycine-2-14C and phenylalanine-3-14C before irradiation.2. Tissues from various organs of irradiated and non-irradiated rats were fractionated into three protein fractions. Glycine, phenylalanine, tyrosine, serine and alanine were isolated from these fractions, and the respective specific activities were determined.3. Differences in specific activities were : decreased activity in muscle collagen and soluble-protein fractions of thymus and spleen; increased activity in soluble-protein fractions of liver and muscle; and variable changes in the activity of certain amino acids of the soluble-protein fraction of kidney.4. The significance of these changes is discussed in terms of known biological effects of radiation on cells and cellular metabolism.5. Muscle collagen seems radio-sensitive and its increased catabolism in irradiated rats could explain much of the excess 14C-activity in ' free '-amino-acid pools.