[Effect of exogamy on morbidity among children during the first three years of life]. / Vliianie ékzogamii na zabolevaemost' detei na protiazhenii pervykh trekh let zhizni.

The incidence of common diseases among children in the first three years of life was studied in relation to the degree of outcrossing in family history, the level of education of both parents, and the age of entering nursery school. A total of 526 children (274 boys and 252 girls) were inspected. The factors under study proved to have no effect on morbidity among children under one year of age. However, morbidity during the second and third years of life depended on the degree of outcrossing in the children's family background, the educational level of their mothers, and the age of their entrance into nursery school. Higher morbidity at this age was characteristic of children born of parents belonging to different ethnic groups, and this situation was independent of social factors. The role of genetic coadaptation and epistasis in determining the relationship between outcrossing and morbidity is discussed.

[Cytogenetic effect of small doses of tritium beta irradiation]. / Tsitogeneticheskii éffekt malykh doz beta-izlucheniia tritiia.

The effect of tritium beta-radiation within the dose range of 0.5 x 10(-3) = 0.6 Gy on human blood lymphocytes in vitro was investigated. Dose-effect correlation was determined by the frequency of aberrant cells and the sum of chromosome aberrations per 100 cells. As compared to a rated curve corresponding to a linear-quadratic model y = a + bD + cD2, experimental curves (showing correlation between cytogenetic indices and a dose) are of abnormal nature with a plateau in a dose range less than 7.5 x 10(-2) Gy. A big confidence interval of cytogenetic effect indices in a dose range less than 7.5 x 10(-2) Gy was shown to be determined by the number of analyzed metaphases. The proof of significance of a plateau on a dose-effect curve in regions of small doses (e.g. with a confidence interval of +/- 24%) necessitated analysis of no less than 10,000 metaphases per dose.

[Effect of pulse and prolonged x-rays in air and in nitrogen on the frequency of sex-linked recessive lethal mutations in Drosophila melanogaster]. / Izuchenie vliianiia impul'snogo i dlitel'nogo rentgenovskogo oblucheniia v vozdukhe i v azote na chastotu stseplennykh s polom retsessivnykh letal'nykh mutatsii u Drosophila melanogaster

The effect of X-irradiation on the frequency of recessive lethal mutations in Drosophila melanogaster sperm cells is studied. Drosophila males were X-irradiated in air and nitrogen in three units with doses rates of 4 X 10(9), 10(11) and 1.7 rad/sec at a dose of 2000 rad. It is found that the mutation frequency after the pulse irradiation was almost twice as low as that after prolonged irradiation. The oxygen effect is eliminated under pulse irradiation, and the data on pulse irradiation in air are similar to those on irradiation at a low dose rate in nitrogen. The data obtained are explained by the presence of short-lived oxygen-dependent damages which are not realized under pulse irradiation due to the lack of oxygen in the track volume.