[Mutagenic effect of pesticides fastac 10 EK and durs ban 4E studied in a micronucleus test iin mouse bone marrow cells]. / Mutagennyi éffekt pestitsidov vaztak 10 EK i durs ban 4E, ustanovlennyi putem mikroiadernogo testa v kostnomozgovykh kletkakh myshi.

The mutagenic activity of vastak and durs ban pesticides was studied by the micronucleus test in mouse bone marrow. The frequency of micronuclei in polychromatic erythrocytes was tested at 24, 36 and 42 h after oral administration of 50% LD50 dose of vastak (14 mg/kg) and durs ban (30.5 mg/kg). Significantly different increase in micronucleated polychromatic erythrocytes was established at 24, 36 and 48 h after vastak administration, and at 24 and 36 h after durs ban treatment. Doses of 25% LD50 for both pesticides showed no mutagenic activity, as judged by the induction of micronuclei in polychromatic erythrocytes.

[Assessment of the genetic risk of radiation by irradiation data from laboratory mammals]. / Otsenka geneticheskogo riska radiatsii po dannym oblucheniia u laboratornykh mlekopitaiushchikh.

An attempt has been made to assess quantitatively genetic risk of radiation for man based on mammalian (mostly mouse) data and using the direct method proposed by UNSCEAR. The parameter employed was induction of reciprocal translocations. Two assumptions were made: human radiosensitivity equals that of the mouse; and dose-response is linear. From observations with acute gamma irradiation the estimate of risk per 10(-2) Gy was as follows: 39 translocation heterozygotes are expected among one million F1 conceptions, 5 cases of multiple congenital anomalies, 25 abortions recorded and 49 unrecorded. Chronic gamma irradiation at dose rates of 1.3 X 10(-5), 1.7 X 10(-4) and 1.0 X 10(-4) Gy/min was 3 to 10 times less effective. Exposure to 4.2 GeV deuterons proved inferior in effectiveness to gamma irradiation. Chronic exposure to 4.1 MeV neutrons delivered at 8 X 10(-4) Gy/min showed 7 times the effectiveness of chronic gamma irradiation. Administration of tritiated water (from 37 to 37 X 10(2) kBq/g b.w.) to rats entailed a risk of the same order of magnitude as external chronic gamma irradiation. Reduction of genetic risk was achieved by pretreatment with either AFT-, ATP-serotonin mixtures or the molecular combinations, Adeturon and Cytriphos. Study of interspecies differences in genetic radiosensitivity showed decline in the following order: rat-rabbit-mouse-Syrian hamster. A dose-rate effect was most clearly seen in the rat, and least clearly in the rabbit. In female mice, examination of oocyte depletion indicated primary follicles to be highly susceptible to acute gamma irradiation; decrease in sensitivity was observed beginning with stage 4. Chronic gamma irradiation was found to be less effective.

[Dominant lethality and translocations in the sex cells of male rats under low-intensity gamma irradiation]. / Dominantnaia letal'nost' i translokatsii v polovykh kletkakh samtsov krys pri gamma-obluchenii nizkoi moshchnosti.

Adult male rats were given 1300 rad of chronic gamma-irradiation (0.08 rad/min) Dominant lethal rates were found to be high (ranging from 48 to 75%) in irradiated postmeiotic cells and clearly lower (6.8%) in spermatogonia. The chromosome aberration (reciprocal translocation) yields observed with 1300 rad chronic irradiation were comparatively low, averaging 1.6%. Spermatogonia irradiation at low dose rate resulted in a smaller effect as compared to the genetic effects of a single acute exposure.

Mouse oocyte dominant-lethal response to chronic gamma irradiation.

Adult mouse females were given 500 rad of chronic gamma rays at 0.01 rad/min and mated to unirradiated males during seven successive weeks to score the frequency of dominant-lethal mutations. Total dominant lethality was increased for any of the weeks post-radiation. Post-implantation dominant lethal yields were low, ranging from 2.5 to 6.1% for individual weeks p.r.

[Chromosome translocations in the sex cells of mice subjected to chronic low-dose gamma-irradiation]. / Khromosomnye translokatsii v polovykh kletkakh myshi pri khronicheskom gamma-obluchenii s nizkoi moshchnost'iu dozy.

Translocation induction in mouse spermatogonia by continuous whole-body gamma irradiation (radium 226) was studied. Total doses, delivered at a rate of 13.0 +/- 1.3 X 10(-4) rad/min for various time intervals, were 97, 195, 294 and 442 rad. Cytological examination within 3 to 4 months after irradiation indicated the presence of translocations in 0.16, 0.30, 0.75 and 1.29 percent respectively, of primary spermatocytes at diakinesis metaphase I. Data on translocation induction (Y) as related to total irradiation dose (D) were best fitted to a second power parabola equation (Y=5.1 X 10(-6)D2 + 7.32 X 10(-4) X D). The results obtained confirm that chronic gamma irradiation is of low genetic efficiency, and support the suggestion that there exists a dose-rate threshold under which no more changes in exposure efficiency will occur.

Chemical modification of genetic damage from continuous irradiation in mice.

It has been demonstrated that Adeturon (S-2-aminoethyl-iso-thiuronium adenosine triphosphate) showed a marked protective effect against translocations induction in mice germ cells after chronic gamma-or neutron-irradiation.