[Biological effects in natural populations of small rodents in radiation contaminated areas. The frequency of bone marrow polyploid cells of bank voles in different years following Chernobyl accident].

On the basis of the metaphase analysis results, the peculiarities of dynamics of the genome mutation frequency (polyploid cells) were studied in bone marrow of bank voles inhabiting the areas with different radiocontamination level due to the Chernobyl accident (8-1526 kBq/m2 for 137Cs) in 1986-1991. Unexpectedly high frequencies of polypoid cells exceeding the pre-accidental level by a factor of 10(1)-10(3) were recorded in all populations studied. Relationship between the frequency of the parameter studied and the concentration of radionuclides incorporated in animal carcasses was proved.

[Biological effects in natural populations of small rodents in radiation-polluted territories. Dynamics of chromosome aberration frequency in a number of generations of European bank vole (Clethrionomys glareolus, Schreber)].

The dynamics of chromosome aberration frequency in bone marrow cells of many generations (14) of bank vole living in the radioactive trace of the Chernobyl catastrophe (1986-1992) has been analysed. The study revealed that the chromosome aberration frequency in voles in the areas with radio-contamination density 220 and 1526 kBq/m2 (for 137Cs) significantly exceeds the control level 3-7 times over the whole period under investigation. The dynamics of the frequency of structural chromosome injuries from 1986 to 1991-1992 is characterised by the tendency to increase in all populations inhabiting the areas with various radio-contamination density (8-1526 kBq/m2).

[Biological effects in natural populations of small rodents in radiation-polluted territories. Description of sites. Dynamics of concentration of gamma-emitting radionuclides in populations of two species of small mammals].

It has been revealed that dynamics of gamma-emitting radionuclide concentration in consecutive generations of two species of wild rodents (European bank vole and yellow-necked mouse) is characterised by the phases of an increase, a maximum content (peaks) and a decrease over 10 years after the Chernobyl accident. The peaks of specific activity of gamma-emitting radionuclides in populations in the areas with different densities of radio-contamination falls not on the first year but on the next ones (1987-1989) after the catastrophe, i.e.

[The dynamic mutability of the somatic and germ cells of animals inhabiting regions of radioactive fallout].

Many generations (1-18) of natural populations of small mammals that inhabited in 1986-1991 areas contaminated by radionuclides, had increased levels of the mutations in somatic cells and gametes. The high frequency of chromosome aberrations in somatic cells of young carps from contaminated ponds was detected in 1988-1992. Radiosensitivity of hereditary structures of animal somatic cells and gametes was increased in subsequent generations as compared with generations that lived in 1986-1988.

[Mechanisms of the antitumor action of spirobromine in mice with leukemia P-388].

The influence of new antitumor drug, spirobromine, a derivative of dispirotripiperazine, on DNA synthesis in tumor cells and organs at different times after its injection into mice with P388 leukemia has been studied. The duration of DNA synthesis inhibition in tumor cells was found to correlate with spirobromine antitumor activity. A certain selectivity of action of the studied compound on DNA synthesis in P 388 leukemia cells as compared to the action on DNA synthesis in bone marrow, small intestine, spleen and liver of tumor animals was observed.

[Tomizine--a new inhibitor of folate metabolism enzymes possessing an antitumor activity].

In the experiments on enzymic systems functioning in the metabolism of folic acid and on transplantable tumors in animals the preparation thomizine (chlorohydrate 4-methoxy-6-aminopyrimido (4,5-b) (1,4) thiazine) was worked out. Thomizine, as well as the known antimetabolite of folic acid-methotrexate, suppresses the activity of dihydrofolate reductase, but contrary to it suppresses FAP enzymic system, inhibiting aminopterin in the organism. Thomizine differes from methotrexate by another spectrum of antitumor effect, selective suppression of the tumor tissue growth, compared with the normal in vitro, it does not inhibit leucopoiesis, shows less toxicity and insignificant cumulative properties.