Thyroid abnormalities associated with protracted childhood exposure to 131I from atmospheric emissions from the Mayak weapons facility in Russia.

Between 1948 and 1960, the Mayak nuclear weapons facility in Ozyorsk, Russia discharged relatively high levels of radionuclides, primarily (131)I, into the atmosphere, resulting in appreciable exposure to the residents of Ozyorsk. To evaluate the association between thyroid diseases and childhood exposure to radioiodines, we screened 894 Ozyorsk residents born between 1952 and 1953. The study population was comprised of 581 exposed individuals living in Ozyorsk during the years of heaviest exposure and 313 nonexposed individuals who moved to Ozyorsk when radiation exposure from Mayak largely had ended.

Tritium radiobiological effects in mammals: review of experiments of the last decade in Russia.

This review briefly describes techniques and basic results of experimental investigations in mice and rats on metabolism, dosimetry, and radiobiological effects of tritium oxide and some tritiated biogenic compounds (glucose, amino acids, and nucleosides) during the last 10 to 15 years in Russia. The content of water in tissue cells of mammals is shown to be 15 to 40% less than in whole tissue. The kinetics of tritium incorporation from oxide (HTO) and its retention in DNA of hemopoietic tissues were studied.

[Damage to the structure of DNA and to the metabolism of nucleic acids in the thymus in relation to the dose of tritium oxide].

Single administration of tritium oxide (1.1-44 MBq per 1 kg of body mass) causes a dose-dependent decrease in the level of rat thymus nucleic acids within the range of concentrations of injected tritium 5.5-44 MBq/g.

[Comparison of the biological effects of tritium oxide and gamma radiation based on changes in the mass of the rat thymus gland].

RBE of tritium oxide (cumulative doses from 0.33 to 14.7 Gy), in comparison with gamma-radiation, amounted to 2-3 as estimated by the thymus mass.

[Effect of tritium oxide in a wide range of doses on the nucleic acid metabolism of the rat spleen].

A single injection of tritium oxide in a dose of 1.1 MBq/g (0.5 Gy for 30 days) was shown to impair the nucleic acid metabolism in the rat spleen.

[Dependence of the damage and recovery of nucleic acid metabolism on the dose rate in tritium oxide exposure].

Disturbance and normalization of nucleic acid metabolism in rat thymus was studied after the effect of tritium oxide delivered in similar cumulative doses but at different dose rates. Both the disturbance and normalization were shown to be a function of dose rate, the slightest damage and the complete recovery being registered at the lowest dose rate (the amount of tritium oxide administered being 0.37 MBq/g/day).

[Changes in the structure and metabolism of rat thymus nucleic acids following cessation of long-term administration of different doses of tritium oxide].

A study was made of the processes of restoration of metabolism and nucleic acid indices in rat thymus after the cessation of the long-term administration of various doses of tritium oxide. The restoration of the indices under study was only observed after tritium dose of 0.37 MBq(g.

[Relative biological effectiveness of tritium oxide based on nucleic acid metabolic indices].

Relative biological effectiveness (RBE) of tritium oxide, as compared to gamma-rays (137Cs), with regard to LD50/30 is 2,32 +/- 0,69 for rats. The RBE coefficients for tritium oxide are obtained with regard to some indices of nucleic acid metabolism in the thymus and spleen during the dose formation (0-14 days). The RBE of tritium oxide increases with a decrease in radiation dose as determined according to the concentration and content of DNA per organ and activity of thymus DNAases.

[Structure of DNA from the rat thymus during prolonged exposure to tritium oxide and external gamma-irradiation].

Thymus depopulation, DNA destruction as estimated according to the level of single-stranded breaks (SSB) and DNA structural derangement revealed by the viscosimetric assay of alkaline lysed thymocytes were observed in the course of a prolonged (1 mos) radiation exposure to tritium oxide (the 1st group) and equidimensional external gamma-irradiation (the 2nd group) in a summary dose of 10 Gy in rats. Depletion and destruction were 1.5-2 times more pronounced in case of HTO exposure.

[Regeneration of nucleic acid metabolism in rat bone marrow and spleen at prolonged intervals after lengthy fractionated irradiation].

A study was made of the content and rate of biosynthesis of nucleic acids in the bone marrow and spleen, the mitotic activity of splenocytes and the lienogram of rats during a year after the end of fractionated irradiation with cumulative doses of 9.7 and 19.4 Gy.

[Nucleic acid metabolism in rat hematopoietic tissues during and after prolonged administration of different doses of tritium oxide].

During the long-term administration to rats of tritium oxide in doses of 0.37, 0.925 and 1.

[Comparison of the structure and catabolism of rat thymus DNA exposed to tritium oxide and gamma-radiation in equal doses].

A decrease in DNA concentration and in the molecular mass of single-stranded DNA, an increase in the PDN content, and activation of acid DNAses in rat thymus were observed after a single administration of tritium oxide in a dose of 22 mBq/g (a cumulative dose of 7.8 Gy) and gamma-irradiation at a corresponding dose-rate and value of the cumulative dose. These changes were most pronounced during the period of dose accretion, i.

[Biochemical study of erythroid hematopoietic reserves during prolonged irradiation].

A study was made of the effect of hydrochloride phenylhydrazine on the content and rate of biosynthesis of nucleic acids in the bone marrow and spleen of rats exposed to long-term fractionated gamma-irradiation (0.5 Gy, 6 times a week). The stimulatory effect of phenylhydrazine on the rate of the nucleic acid biosynthesis was shown to decrease in the tissues under study with dose cumulation from 2.

[Structure and repair of rat thymus DNA during long-term irradiation].

During long-term fractionated irradiation (0.5 Gy, daily) the molecular weight of single-stranded DNA of the thymus of exposed rats remained the same as that of intact animals till the dose of 25 Gy had been cumulated. The integrity of the DNA structure was ensured by the repair of DNA and elimination of cells with unrepaired lesions.

[Incorporation of tritium into the DNA of hematopoietic tissues during prolonged administration of tritium oxide].

With long-term (90 days) administration of tritium oxide (0.37 MBq/g body weight) to ras the carbon-bound tritium accumulated in DNA of haemopoietic tissues during two-month administration of the isotope (the accumulation half-time of 15-25 days); during the next month, the isotope level remained nearly constant (about 20 X 10(6) decay/min/g DNA). Elimination of tritium from DNA started 3 days after termination of its administration and proceeded with two half-times (4-8 days and 12-18 days).

[Study of the structure and metabolism of the rat thymus gland during long-term administration of tritium oxide in different doses].

During-3-month administration of tritium oxide (0.37, 0.925 and 1.

[Characteristics of nucleic acid biosynthesis in the activation of erythroid cell proliferation due to prolonged gamma irradiation].

Most important differences were detected in the nucleic acid metabolism in the rat spleen with increasing proliferation of erythroid cells under the effect of long-term gamma-irradiation and acute hemolytic anemia. It is assumed that humoral regulation pathways and molecular mechanisms of changes in erythropoiesis depend upon haemopoietic stem cell pool.