Biomedical subjects
Publications and source records attributed to V Volf.
Studies with pure LICAM(C) and with its methyl esters showed that all the substances caused increased renal retention of plutonium-238 in the kidneys of mice and rats but were equally effective in reducing plutonium retention in bone and liver.
It was demonstrated in rats that it is possible to reduce the retention of 239Np in all body tissues by an early combined treatment with small doses of DTPA and DFOA. The content of 239Np can be decreased in soft tissues even if treatment is delayed. Promptly administered LICAM(C) proved more effective than the above chelate combination in reducing 239Np retention in the bones but increased that in the muscles and especially in the kidneys. This side effect of LICAM(C) could be partly prevented by simultaneous treatment with DTPA.
The relative effectiveness of Ca-DTPA and Zn-DTPA as a function of the dose, number of doses and time of their administration in removing 234Th that had been administered as the citrate or nitrate from various rat organs was investigated. With a single early treatment (1.5 min after intravenous injection of 234Th), Zn-DTPA was clearly less effective than Ca-DTPA over the whole dose range (30 mumol/kg body weight-1000 mumol/kg body weight) tested. In the skeleton, 1000 mumol Zn-DTPA/kg removed as much 234Th (about 50%) as 30 mumol Ca DTPA/kg. Prompt treatment with 100 mumol Ca-DTPA/kg body weight diminished the skeletal 234Th content by about 70%; but when it was delayed by 6 h or 4 d, the 234Th content was reduced by only about 20% and 10%, respectively. The effect of DTPA in the bone was independent of 234Th compound, while in the soft tissues 234Th injected as nitrate was less affected than the citrate. The effect of DTPA was potentiated when treatment was repeated; the end effect was dependent on the time of the first DTPA injection and on the total number of doses. Thus, about 90% and 50% less 234Th was found in the bones after repeated treatment started at 1.5 min and 4 d after administration of 234Th, respectively. Under the conditions of a delayed repeated treatment, Ca-DTPA and Zn-DTPA were equally effective.
The effect of Np mass and the acidity of the administered Np solutions as well as the age, sex and nutritional status of the animals injected or gavaged with 239Np or 237Np were determined. The latter factor proved to be dominant for absorption of Np from the gut. Thus in fasting weanling and young adult male rats, the absorption of 239Np was sixfold higher (0.18% and 0.12%, respectively) than in fed ones (0.03% and 0.02%, respectively). Absorption by fasted adult females was 0.05% of the administered 239Np, about half of that of adult males. Raising the Np-mass gavaged to fasted female rats to 1 and 10 mg 237Np/kg resulted in an absorption of 0.23% and 0.26%, respectively. Thus, an increased absorption of Np in adult rats seems to be expected only if a large mass is ingested. No dependence of the absorption of Np on nitric acid concentration was found. The data obtained after oral administration of 238Pu and 239Np to adult rats suggest that the f1 factor recommended by the ICRP for fractional absorption of soluble Np compounds from the gut should be decreased, whereas the f1 factor for soluble Pu compounds should be raised.
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The translocation of 234Th from a simulated wound site and the efficacy of DTPA administration, as a function of the thorium compound injected as well as the DTPA treatment schedule, have been investigated in rats. Much more 234Th injected as citrate was translocated from the injection site than after administration as nitrate, whereas the distribution pattern of 234Th translocated to the various tissues was nearly identical for both 234Th compounds. Combined local and systematic treatment with DTPA was equally or more effective than each of the treatments alone in reducing the retention of 234Th at the injection site and in the organs.
This interim report summarizes the results of observations during the first year after a single injection of 237Np nitrate (0.2 or 1.0 mg/kg body weight) into adult female rats and further preliminary data obtained with young animals. The retention of 237Np was followed by whole body counting and serial sacrifice of groups of animals. The retention data could be fitted to three-component exponential equations which show no major differences between the two 237Np dose levels. The half-times and extrapolated initial fractions calculated from the first two exponential terms indicate that one fraction, representing about 40 per cent of the injected 237Np was excreted within the first 5 days and an additional 15 per cent within the first 5 months, while the rest was excreted with a half-time of about 3.5 years. This final long term component is assumed to indicate the rate of loss of 237Np from the skeletal compartment. In young animals both whole-body and skeletal retention of 237Np during the first 5 months of observation was about 50 per cent higher than in the adults. Several soft tissue tumours, mostly mammary tumours, have appeared to approximately the same extent in both control and 237Np treated adult rats but no osteosarcomas were detected up to 15 months after injection of 237Np.
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The results of pilot experiments on metal interactions in vivo are presented. In rats pretreated with a single injection of Cd, substantially less Pu accumulated in the liver, while significantly more was found after pretreatment with Cu. In bone, somewhat more Pu was detected after Cd and less after Cu administration. Both metals increased the retention of Pu in the kidneys and spleen. The changes were similar with 238Pu and 239Pu and were still present 1 wk after Pu administration; in the case of Cu they were dependent on the amount administered. All the changes described concern solely the tissue distribution pattern of Pu; the total amount of Pu retained in the organs studied remained the same. The possible relation of Pu uptake to induced synthesis of Cd-thionein and Cu-chelatin is discussed.
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