Radiation reactions and the possibilities for their modification in rats exposed in the area of the Chernobyl Atomic Electric Power Station]

A study was made of some embryological, hematological, cytogenetic and biochemical characteristics in Wistar rats exposed within the Chernobyl NPP zone over a period of 30 days (the average radiation background level, 75, and at the soil surface, 115 mR/h; a cumulative dose, 57 rad/30 days, and for pregnant rats, 36 rad/20 days). The quantity of chromosome aberrations in bone marrow metaphases and the embryonal death rate were invariable; some cases of teratogenesis were, however, observed. The total number of karyocytes in the brain and the leukocyte content in the peripheral blood sometimes decreased. The changes in certain characteristics (such as the content of endogenous amines and thiols in the liver and spleen) of the endogenous radioresistance background (ERB) and the normalization of the ERB by the radioprotective agent MIGI-K were found.     

The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 1. The experimental model. The radiation loads on animals kept continuously under external and internal radiation exposure in the area of the Chernobyl Atomic Electric Power Station]

Irradiation conditions in which laboratory animals were kept in experimental laboratories of Chernobyl and Kiev after the accident at the Chernobyl A.P.S. are described. The data are presented on the spectral structural and activity of radionuclides in the diet as well as in the organs and tissues of the animals. The radiation loads have been estimated with regard to an external gamma component and the internal one contributed by the incorporated radionuclides. It has been shown that radiation doses received by the animals during their lifetime due to these contributions do not exceed units of cGy.     

The structural-functional disorders in the liver of wild rodents from areas of the accident at the Chernobyl Atomic Electric Power Station]

A study was made of the morphological status of hepatocytes, the antioxidant activity of lipids and composition of phospholipids, and dehydrogenase activity in the liver of field mice taken from seven regions of the Chernobyl A.P.S. zone with different levels of contamination in 1987. There observed multiple types of destructive damages to the organ; depletion of liver lipids by antioxidants; diminution of phospholipids within the total lipid level; considerable increase in the phosphatidyl choline/phosphatidyl ethanolamine ratio and in the relative content of phospholipid lysoforms; and inhibition of dehydration processes. In the absence of a strict correlation between the changes in the biophysical and biochemical parameters or between the severity of degenerative changes in hepatocytes and the level of external irradiation, certain relationship was followed up between liver lipid depletion by antioxidants, inhibition of dehydration processes and the number of wild rodents which developed dystrophic changes in the organ. These structural and functional changes were found in the liver of wild rodents taken from all the regions: this indicated a considerable sensitivity of the parameters of the regulatory cell systems and hepatocytes to the effect of technogenic contamination.     

The effect of the accident at the Chernobyl Atomic Electric Power Station in 1986 on the fish population of a cooling pond]

The cytogenetic analysis of Cyprinus carpio eyes, developing Blicca bjoerkna L. eggs, and eggs and larvae of Hypophtalmichthys molitrix Val. has demonstrated that the yield of cells with chromosome aberrations in the fish species under study is normal, while the level of variability of morphometric indices in offspring is considerably higher than that in parent fish.     

The levels of soil pollution with plutonium isotopes in the Bryansk Oblast (following the accident at the Chernobyl Atomic Electric Power Station)]

The estimates of plutonium concentration in soils of Western regions of Bryansk (Krasnogorsky, Novozybkovsky, Zlynkovsky and Klintsovsky) are presented. The levels of soil contamination with plutonium within the regions examined vary by 4-5 times, although no definite geographical direction of pollution intensity within the territory examined is noted. The cumulative concentration of isotopes (238Pu, 239Pu, and 240Pu) varies within 21-112 Bq/kg.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 5. Longevity and the carcinogenic effects]

Remote effects in laboratory animals living in conditions of exposure to a mixture of external and internal radiation resulted from the Chernobyl A.P.S. disaster have been investigated. It has been found that the rate of deaths from non-tumor illnesses grows, the incidence of neoplasms increases and their latency time decreases. The redistribution within the spectrum of benign and malignant tumors and the increase in the multiplicity coefficient have been revealed. It is concluded that chronic exposure of animals to low-level radiation from the radionuclides, resulted from the accident, brings about a much larger number of negative stochastic and nonstochastic remote effects as compared to those expected from the extrapolation of the effects produced by high radiation doses.     

The ultrastructural characteristics of the bronchial mucosa in chronic inflammation in participants in the cleanup of the aftermath of the accident at the Chernobyl Atomic Electric Power Station]

Bronchial biopsies from persons exposed to radiation after the Chernobyl accident with clinically verified chronic bronchitis were studied by electron microscopy. The results demonstrate transformed alterative, compensatory-adaptive and inflammatory reactions in bronchial mucosa of contingent. Nevertheless, their integral significance does not alter the nosologic form, and some structural equivalents have dynamic expression.     

The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 2. The state of bone marrow hematopoiesis in rats]

It has been shown that rats born during the first months after the Chernobyl A.P.S. disaster exhibit essential changes in the peripheral blood and bone marrow haemopoiesis throughout the entire lifetime. Rats brought up in Chernobyl from the age of three months on display even more pronounced changes. It is assumed that the changes in the haemopoiesis develop due to the continuous influence of low-level radiation of different quality and are attributed to the effect of the incorporated radionuclides.     

The effect of low doses of radiation on the glutathione status in children and adults after the Chernobyl Atomic Electric Power Station accident

A level of glutathione in the blood plasma of human population exposed to low-dose radiation after the Chernobyl accident was studied; a complicated character of dose dependence was shown. The response of the glutathione system to low and high radiation doses is different in the children living in the radionuclide-contaminated areas and in the participants of the elimination works.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 10. Cooperative immune reactions in different generations of mice]

The immune status of mice has been assessed by the whole complex of data. The permanent action of low-level radiation has been shown to suppress considerably the rate of reactions of the delayed-type hypersensitivity and "graft versus host" disease, as well as NK and specific cytolytic T-lymphocyte activity. The dynamics of accumulation and the levels of antiviral antibodies in the serum, lung and trachea extracts are virtually invariable. The resistance of experimental animals to influenza is lower than that of non-irradiated mice of the same line and age. The data obtained indicate that the immune disturbances revealed are connected not only with the alteration of lymphoid cell populations, but also with the alteration of the immune regulation mechanisms.     

Genetic effects in mice exposed to the 10-km area around the Chernobyl Atomic Energy Station

Mice (CBAxC57BL) F of both sexes were exposed within the 10 km zone of Chernobyl nuclear power station. Genetic damage of phone chronic effect of increased radiation in exposed adult mice and in the course of embryogenesis was studied. The total absorbed radiation doses in testes varied from 1.85 to 0.42 Gy in embryos and from 3.4 to 2.7 Gy in adult males. Increase of dominant lethal mutations (DLM) and abnormal sperm heads (ASH) was only observed right after the end of exposure of adult males. The yield of reciprocal translocations (RT) in these males was relatively low. Among the males exposed at the stage of early embryogenesis, 4 heterozygotes for RT were revealed. In other males of this group the RT yield was low.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 9. The morphofunctional indices of the immunocompetent organs in mice]

The permanent action of small doses of low-intensity radiation on the immune status of 2.5-3.5 month CC57W mice has been investigated. Total doses of internal and external irradiation were about few cGy. The permanent action of low-level radiation on the experimental animals of the first and fourth generations was shown to change spleen and lymph nodes weights and the count of lymphocytes isolated from these organs. Cellularity and DNA synthesis in the lymph-node lymphocytes and their proliferative response to polyclonal mitogens also changed. The alterations in the parameters that characterized T-lymphocyte population were statistically significant.     

The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 4. The morphological and ultrastructural changes in the liver of rats]

A study was made of the morphological and ultrastructural changes in hepatic tissue of rats lived within the Chernobyl accident zone during the period of 6 to 25 months. Considerable nonspecific changes in hepatocytes (fatty, vacuolar and parenchymatous degeneration, and hepatocyte necrobiosis) were seen throughout the entire period of observation. Coagulation necrosis of certain hepatocytes, Kupffer and endothelial cells, and the development of microcholangiomas by the end of the second year were the most characteristic alterations.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 3. The morphological and ultrastructural changes in the lungs of rats]

The morphological and ultrastructural changes revealed in the lungs of rats kept within the Chernobyl accident zone during the period of 6 to 24 months were shown to be uniform and multicomponent. The changes were found both in the respiratory and the vascular connective tissue. The inflammatory processes occurred with formation of pneumonic foci, hypo- and disatelectasis, emphysematous changes, impairment of interalveolar septa, and connective tissue cell proliferation. In the lung tissue, focal and diffuse lymphoid proliferates and, at later stages, lymphomatous changes were revealed.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 8. The status of cellular immunity in different generations of rats]

In studying immunity in laboratory rats of different generations (P, F1 and F2) brought up in Chernobyl in 1989-1990 the authors have revealed the development of leuko- and lymphopenia; decrease in the absolute content of immunocompetent cells bearing Fc receptors to IgG; stable and long-lasting suppression of blood NK cell activity; reduction of antibody-dependent cytotoxicity; and changed ability of blood lymphocytes to interact contactly with allogenic mast cells. The most considerable disorders have been found in 6- and 9-month-old F1 rats and in 3- and 6-month-old F2 rats.     

The biological effects in animals related to the accident at the Chernobyl Atomic Electric Power Station. 6. The physiological development and cytogenetic indices of the progeny of rats]

Certain alterations have been revealed in the postnatal ontogenesis parameters of albino mongrel rats and their descendants constantly kept within the thirty-kilometer zone of the Chernobyl A.P.S. Structural disturbances have been found in bone marrow cell chromosomes.     

The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 11. The ultrastructure of the bone marrow cells in different generations of rats]

In studying the bone marrow cell ultrastructure in male rats (F0-F2 generations) aged 3 months, which were brought up within the thirty kilometer Chernobyl A.P.S. disaster area, considerable submicroscopic changes have been revealed in the cells at all stages of maturation, including undifferentiated blasts and mature forms of cells of the neutrophilic, eosinophilic, monocytic and erythroid haemopoiesis series, as well as stromal elements of the microenvironment, megakaryocytes and endothelium. The severity of these changes increases, as the number of generations grows, displaying frequently a destructive character.     

The functional status of the hypophyseal-adrenal cortical adaptation system in children in Byelarus living under the action of low doses of radiation after the accident at the Chernobyl Atomic Electric Power Station]

The analysis of the status of sympatho-adrenal and hypophysis-adrenal medulla systems of adaptation in children living in territories contaminated by radionuclides was carried out. A decrease in the catecholamine level in children's urine and hyperactivity of the hormonal response of adrenal medulla to endogenous ACTH indicated the reduced ability of adaptation and decreased resistance of children's organisms to stress factors of the environment.     

Postradiation changes in the brain asymmetry and higher mental functions of right- and left-handed subjects (the sequelae of the accident at the Chernobyl Atomic Electric Power Station)

The present study was aimed at comparative electrophysiological, clinical, and neurophysiological assessment of the brain functional state in dextrals (50 men) and sinistrals (5 men), who participated in the Chernobyl clean. The patients were observed over the course of 10 years (from 1990 to 1999). The results of examination of healthy persons (20 dextrals and 10 sinistrals) were used as a control. The clinical examination revealed the earlier manifestation and more severe development of paroxysmal and epileptic seizures in sinistrals than in dextrals. Electrophysiological study showed a progressive decrease in interhemispheric asymmetry of the EEG coherence characteristic for a healthy brain to inversion of its sign. These changes were more pronounced in sinistrals. In the remote terms after radiation, the interhemispheric EEG coherence decreased over the whole cortex, especially, in the frontal and central areas in both groups of patients. Neurophysiological study revealed a progressive impairment of voluntary motor activity and tactile sensibility, especially, in the left hand. These defects were more expressed in sinistrals than in dextrals. The results of complex and longitudinal examination suggest that the observed changes in brain asymmetry and interhemispheric interaction can be not only a result of a dysfunction of subcortical limbic-reticular and mediobasal brain structures but also a result of the white matter damage including corpus callosum. More expressed impairments in sinistrals than in dextrals can be explained by specific morphofunctional organization of the brain in persons with different sensor and motor asymmetries.