Aqueous solutions of pyrimidines (such as uracil and thymine) containing N₂O (125 mM) were irradiated with Co-60 gamma rays source and analysed with paper chromatography technique using suitable solvent developing systems. Among the various radiation-induced products, the three different products located with lower Rf values are U. V. absorbing in character. Spectroscopic analysis such as N.M.R., U.V. and mass spectrometry showed tentatively that these products are dimeric compounds; silylation technique assisted for such investigation. These dimers are the major products in the radiolysis of the pyrimidines and N₂O system ; uracil produced dimers which constituted 71% of the total uracil loss and thymine 33%.

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Radiocalcium was injected to adult animals at the doses of 0.5 μCi/g body weight and 1.0 μCi/g body weight. Animals were sacrificed at intervals of 1, 3, 5, 7 and 14 days after injection. Thymus and spleen were studied for histopathological damage produced.
There occurred a maximum depopulation of cortical lymphocytes of the thymus at day 5 and 7 and the normal structure of thymus restored at day 14 with the occurrence of some abnormal cells. Marked extramedullary hematopoietic foci appeared at day 7 with the predominance of blast cells which differentiated into granulocytopoietic and megakaryocytopoietic. cell lines at day 14. Spleen gave a more drastic response than the thymus.

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In a span of about one month after the inhalation of plutonium nitrate aerosol in the adult Wistar rats, the whole body retention of plutonium decreased with three different exponential terms and they had approximate half-lives of 1.5 days, 8 days and 80 days, respectively. These terms may correspond to fractional parts of plutonium deposited on the upper respiratory system, on the lower respiratory system and transferred to the other organs from the lung and then eliminated from those organs, respectively.
Plutonium once deposited in the lung remained in the deposited site for relatively long time and was transferred gradually to the skeleton. The half-time value for the retention of plutonium in the lung of the rat was 77 days.
The fractional retention of plutonium in the lung and the skeleton 80 days after inhalation were 0.65 and 0.20, respectively.
In case of the inhalation, the amount of plutonium transferred from the lung to liver was lower than in the case of the injection in vein or in muscle.
Following the inhalation exposure of soluble plutonium compounds, the concentrations of plutonium in the remained cadaver, the tail, the spleen and the gonad are steadily increasing, while those in the lung and liver are decreasing or not increased.
The concentration of plutonium in the blood was sufficiently high to be detectable at one month after inhalation, in case of intake of soluble plutonium compounds.

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The objective of this study is to compare whole-body retention in the rat of radiocobalt incorporated into a marine green alga with that of ⁶⁰Co in inorganic form. Ulva pertusa was incubated in aerated seawater containing ⁶⁰Co under fluorescent lamp for 7 days. The radioactive seaweed was homogenated and was given to rats via a stomach tube. The control group of rats was given ⁶⁰CoCl₂ with homogenate of non-radioactive seaweed. Whole-body retention of the radionuclide was determined by in vivo counting of the living animal. The result revealed that rats absorbed and retained much more ⁶⁰Co incorporated into the seaweed than ⁶⁰CoCl₂. This fact should be taken into account in the estimation of internal dose due to radiocobalt released into marine environment.

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The translational ability of RNA directed by irradiated calf thymus DNA or deoxyribonucleoprotein (DNP) in vitro was investigated.
Both the template activity of calf thymus DNA for RNA synthesis and the incorporation of amino acids into acid insoluble materials in vitro markedly decreased by irradiation with 20 increasing dose.
The activity of calf thymus DNP, however, increased with irradiation at a dose lower than krads. The incorporation of amino acids also increased with the same dose.
It was shown that the translation dependent on the RNA directed by irradiated templates was qualitatively different from that of unirradiated templates.

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