Biomedical subjects
Publications and source records attributed to N S Shvydko.
A study was made of the ability of plutonium to bind to a complex with amino acids, organic and inorganic acids of normal blood serum. Among the low molecular weight addends bicarbonate ions play a major role in plutonium binding. In this respect, possible mechanisms of plutonium metabolism in the blood are discussed.
The paper deals with the effect of iron preparations on the excretion of plutonium 239 from a body at a later stage of the radionuclide metabolism. The experimental results show that oral administration of the iron preparation at a later stage of 239Pu metabolism enhances the radionuclide excretion both in urine and in faeces. On the basis of the results obtained the coefficients are calculated for 239Pu excretion in urine and faeces and for its content in the organs of deposition. This may be used for increasing the sensitivity of indirect dosimetry of plutonium-239 within the body.
A technique has been developed for the determination of americium 241 in urine by a radiochemical purification of the nuclide from uranium (upon co-precipitation of americium 241 with calcium and lanthanum), plutonium, thorium, and polonium 210 (upon co-precipitation of these radionuclides with zirconium iodate). alpha-Radioactivity was measured either in a thick layer of the americium 241 precipitate with a nonisotope carrier or in thin-layer preparations after electrolytic precipitation of americium 241 on a cathode.
The influence of macro amounts of iron on 238Pu metabolism in the animal body has been studied. The data obtained indicate that 238Pu metabolism parameters change under the effect of iron. The efficiency of the agent used is demonstrated by a diminished deposition of the radionuclide in bone tissues and an increased (by 2.65 times as compared with the control) excretion of plutonium 238 in faeces.
In order to increase the informativeness of the indirect dosimetric estimates of plutonium-239 body levels complex makers are widely used to enhance natural excretion of the radionuclide in urine, the ratio between 239Pu levels in urine and skeleton being measured. However, as the onset of chelate application is postponed its efficacy, with respect to the skeleton, sharply decreases making it impossible to obtain reliable information concerning plutonium 239 levels in bone tissues at later times.
A study was made of the role of biocomponents of bile, urine and feces in the elimination of plutonium and americium from the organism. Plutonium 239 and americium 241 were separated in bile due to higher tropism of plutonium to low molecular weight ligands, and of americium, to a protein-containing fraction. The status of plutonium excreted in feces was the same as the physicochemical status of americium. Plutonium 239 and americium 241 eliminated in urine were in a completely ultrafiltered state.
A study was made of the dependence of plutonium distribution among organs and tissues on the time of administration of iron preparation. Iron decreased the share of plutonium in bone tissues, somewhat increased it in soft tissues, and enhanced the excretion of the radionuclide from the organism. The protective efficiency of the preparation in relation to bone tissue was associated with the time of the administration thereof.
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The estimation of plutonium in soils of the contaminated after Chernobyl accident areas of Bryansk Region (Russia) are presented. On the basis of data about Pu concentrations in soils and by means of migration models in "soil-man" system the doses received were assessed. Pu-239, 240 and Pu-238 were determined in samples of autopsy material (lung, liver, bones and tracheobronchial lymph nodes) of residents from Chernobyl-fallout contaminated regions. Effective doses have been obtained by means of data about Pu-concentration in autopsy samples.
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