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The study of pathogenic activity of neutrophils under chronic low-dose irradiation (total doses were 0.84-24.99 Gy) was carried out. The stage of phase changes was followed by a stable increase in neutrophil phagocytic activity, according to absorbing capacity, at relatively high total doses of irradiation. The data obtained were considered as a defence-compensatory reaction caused by decrease and depression of digestive capacity of phagocytes.

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Genetic structure was studied in cells of F1 posterity whose parents had survived irradiation exposure (2.2-6.6 Gy) 6-13 years ago. In juvenile monkeys (F1) aged from 1.5 to 2.5 years the frequency of aberrations exceeded reliably the spontaneous levels but was considerably lower than this in their irradiated parents. Chromosome aberration types coincided with those of the control ones. The changes revealed in the bone marrow cells of the posterity from irradiated individuals can be regarded as an intensive spontaneous mutational process.

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High level of chromosome aberrations has been determined in different types of somatic cells of monkeys which were subjected to general daily repeated low-capacity radiation (0.049-0.0078 Gy per a day) and accumulated summary doses of about 8.26-36.77 Gy. Long persistence of cytogenetic irradiation aftereffect (15-19 years of observation) has been shown. Differences are revealed in the frequency and types of chromosome aberrations in tissues with different level of cell proliferation: in bone marrow, peripheral blood lymphocytes and epithelial renal cells of irradiated monkeys.

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A comparative study of chromosome structures of bone marrow and peripheral blood cells has been carried out in 8 rhesus macaques (2-7 years of age), 4 of which survived after prolonged low-capacity (3.87 microA/kg) gamma irradiation, the total dose being 7.97 Gy (LD50/60). It has been established that prolonged low-capacity gamma irradiation was of a high mutagenic activity. Various tissues of irradiated monkeys showed differences in the frequency (4 months) and types (4-33 months) of aberrations within the period of 4 to 33 months following irradiation. Mutagenic effect characteristic of the early period after the irradiation was retained in the peripheral blood of irradiated monkeys within the period of observation.

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The effect of prolonged gamma-irradiation with doses of low intensity (3.87 microA/kg) was studied in the bone marrow cells of monkeys (Macaca rhesus). The cumulative dose was 214.14-221.88 mC/kg. Statistically significant differences in the frequency of chromosome aberrations and the percentage of polyploid bone marrow cells, as compared to the level of spontaneous aberrations, were observed during 42 months following the exposure.

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Frequencies of stable chromosome rearrangements in bone marrow cells of rhesus monkeys (Macaca mulatta) have been determined for following time periods: from 0.25 to 6.0 and from 10.0 to 18.0 years after gamma-irradiation at doses of 154.8-167.7 mC/kg. The time of the occurrence of pathological clones and the character of their formation in those cells, whose markers were presented by chromosome rearrangements of the same type, have been defined. Some animals showed the tendency towards the increase in the frequency of uni-type rearrangements in the pathological cell clones. This phenomenon could be a potential precursor of the pathological processes in irradiated individuals.

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A mutagenic effect of aflatoxin B1 (AFB1) was studied in somatic cells of primates. It is shown that AFB1 elevates the chromosome aberration frequency in bone marrow cells of two monkey species: Macaca mulatta and Papio hamadryas. Genome mutations were found in these experimental primates simultaneously with chromosome aberrations. The AFB1-induced chromosome aberrations were revealed at least during two years of the study. The fact of the chromosome aberration frequency increase was established in Macaca babies born from females who received AFB1 in pregnancy.

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A mutagenic effect of aflatoxin B1 (AFB1) in somatic cells of primates is investigated. It is shown that AFB1 elevated the frequency of chromosome aberrations in the bone marrow of two species of monkeys: Macaca mulatta and Papio hamadryas. Beside chromosome aberrations, genome mutations were found in these experimental primates. AFB1-induced chromosome aberrations were constantly revealed during two years of study. Increase in the frequency of chromosome aberrations could be demonstrated in Macaca babies born from females that had received AFB1 at the final stage of pregnancy.

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Spontaneous chromosome reconstructions were examined in bone marrow cells, peripheral blood lymphocytes and epithelial kidney cells from monkeys (Macaca mulatta). In normal monkeys, the chromosome reconstruction frequency was higher in epithelial kidney cells and lower in bone marrow cells. Peripheral blood lymphocytes occupied an intermediate position as regards the chromosome reconstruction frequency. The structural chromosome mutations were characterized mainly by single and twin fragments, with the former ones being predominant. The monkeys examined showed age-associated differences in the frequency of spontaneous chromosome reconstructions.

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The statistical reliable cytogenetic effect on bone marrow cells of mice and monkeys was achieved by means of dosage hypoxic hypoxia produced by breathing of gas hypoxic mixture containing 10% oxygen and 90% nitrogen (GHM-10). The effect was detested after total irradiation of mice and local irradiation of monkeys. The dose of irradiation was 100 rad (10 R/min and 17.4 R/min).

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Cytogenetic consequence of irradiation was studied in epithelial monkey kidney cells in 3.5-9.0 years after repeated daily small dose irradiation (2.99-4.9 r every day) and in 6.0-12.5 years after a single irradiation (550-652 r). The number of reconstructed chromosomes has been found to exceed spontaneous chromosome exchanges. The reconstruction of non-stable type has been also observed. Cytogenic consequency of irradiation was due to the experiment conditions and to the total dose of irradiation.

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Using 48 Macaca rhesus undergone acute single does and prolonged small dose daily irradiation, a long-term preservation of reconstructions in the pair of marker nucleolus-forming chromosomes has been shown. The animals were examined in different periods from irradiation, ranging from 3 months to 16.5 years. The frequency of retained reconstructions in the long arms of chromosomes was reliably above the frequency of alterations in the short arms. Reconstructions in the long arms of the marker chromosome were seen in the heterochromatin area after differential chromosome staining. Alterations in the functionally active area of the short arms of the marker chromosome retained extremely rarely being observed only in monkeys that survived through long-term small-dose irradiation.

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During the period that lasted from 4 to 11 years after the cessation of the long-term daily gamma-irradiation the frequency of chromosome rearrangements in peripheral blood lymphocytes of monkeys exceeded the control level. The number of rearrangements did not change significantly at different total irradiation dosses (from 826 to 3677 r). The main type of structural chromosome rearrangements were symmetrical chromosome exchanges. Abnormal cell clones in peripheral blood lymphocytes of monkeys irradiated at low doses had no selective advantages during the periods of investigation.

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