[Cytogenetic investigations of mice marrow cells after isolated chronic exposure to radiation and chemical factors, and combined sequential exposure to these factors].

The article presents data on chromosomal aberrations in bone marrow cells of mice following isolated exposure to gamma-radiation and chemical factor within the existing MPCs for piloted spacecraft, and also combined sequential exposure in the ranges predicted for interplanetary missions. In the event of chronic exposure the relative number of chromosomal aberrations goes up till reaching plateau and is governed strictly by the mathematical dependence on effective residual gamma-dose and effective damage of organism from inhaled chemical factor. Sequential exposure to the radiation and chemical factors within the ranges specified for orbital and remote space missions caused a tangible reduction of the speed of cytogenetic damages reparation in postexposure period which may be interpreted as depletion of the body reserve and compensatory-recovery potential.

[Adaptation processes in mice during chronic combined exposure to radiation and chemical compounds (acetone, ethanol, acetaldehyde) innate to exploration missions].

The paper reports the results of experimental investigation with mice subjected to 63-day of daily 10-fold fractionated gamma-irradiation at the total dose of 350 cGy followed by 70-day exposure to chemical mixture (acetone, ethanol, acetate aldehyde) at close to maximum permissible concentrations innate to piloted space vehicles (MPCpsv). Measured levels of radiation and known radiation sensitivity of mice were used to model absorbed dose to cosmonauts on an exploration mission. Functional shifts in the hematopoietic system and changes in biochemical parameters of erythrocytes indicative of energy exchange and redox potential were tracked up during the combined radiation-chemical exposure and 90 days of recovery. It was shown that adaptation caused pronounced and strongly pronounced tension of regulatory mechanisms, particularly under the effects of radiation. High tension still persisted in the recovery period.

[Evaluation of the risk of delayed adverse effects of chronic combined exposure to radiation and chemical factors with the purpose to ensure safety in orbital and exploration space missions].

The work had the aim to anatomize the existing issues with providing safety in extended orbital and exploration missions for ensuing estimation of actual values of the total radiation risk for the crew, and risks of other delayed effects of simultaneous exposure to ionizing radiation and chemical pollutants in cabin air, and a number of other stressful factors inevitable in space flight. The flow of chronic experiments for separate and combined studies with reproduction of air makeup and radiation doses in actual orbital and predicted exploration missions is outlined. To set safety limits, new approaches should be applied to the description of gradual norm degradation to pathologies in addition to several generalized quantitative indices of adaptation and straining of the regulatory systems, as well as of effectiveness of the compensatory body reserve against separate and combined exposure.

[Chromosomal aberrations upon isolated and combined exposures to chemical substances and ionizing irradiation].

The partial summation of biological effects evaluated by the anaphasic chromosomal aberration test in the bone marrow karyocytes of mice was determined when the animals were concurrently exposed to chemical substances (acetone, acetaldehyde, ammonia, and ethanol) at low concentrations and gamma-irradiation in a total dose of 30 Gy. Qualitative analysis of chromosomal aberrations in the karyocytes of the bone marrow (ponses, fragments) has indicated that upon combined exposure of the animals to the chemical substances and gamma-irradiation, the chemical factor is dominant since upon combined radiochemical exposure, the number of chromosomal aberration increases mainly at the expense of fragments (91.2%), as does upon isolated exposure to chemical substances (96.4%).

[Cytogenetic and biochemical reactions of experimental animals to combined exposure to low-intensity radiation and chemical factors].

Combined exposure of mice to a mixture of chemicals in small quantities and gamma-radiation at a total dose of 30 sGy cause partial summation of biological effects assessed by cytogenetic disorders in nuclear cells of the bone marrow and changes in erythrocyte metabolism. The level of cytogenetic damages in bone marrow cells remained increased till day 14 of recovery, whereas following exposure to chemicals or radiation alone the number of chromosomal aberrations (ChA) was nearly same as in control at this point of recovery The anaphase method showed prevalence of ChA in the form of fragments over bridges in marrow karyocites. The combination of factors suppressed energy-producing processes in erythrocytes (reliable reductions in lactate dehydrogenase and lactate) and activated oxidation processes (reliable decrease in reduced glutathione). Functional shifts in erythrocyte metabolism persisted till day 30 of recovery Based on results of the investigation, functional status of organism following low-intensity exposures can be assessed, along with cytogenetic, also by indices of erythrocyte metabolism.

[Cytogenetic and biochemical assay of an unidirectional effect of chronic combined exposure of laboratory animals to isoeffective concentrations of chemical substances].

Chronic combined exposure to low concentrations of chemical substances (equal to the maximal admissible limits for space vehicles) is fraught with an increase in chromosomal aberrations in bone marrow cells as compared with the spontaneous chromosome aberration rate. In addition to the cytogenetic evidence, there were also statistical phase shifts in metabolic parameters of erythrocytes (enzymes involved in the basal metabolism and a number of metabolites), leukocyte count in peripheral blood, and the total quantity of karyocytes in the bone marrow. No significant changes were found in organs of the immune and reproductive systems.

[Role of human olfaction in detection of space vehicle air contamination by gases emitted during thermal destruction of polymers].

The paper deals with the ability of human olfaction to identify odours associated with thermal destruction of polymers. The investigations confirmed the ability of early detection of equipment overheating and subjective odour evaluation using the 5-point intensity scale and calculating the relation of odour intensity to the maximum admissible concentration of volatile chemical contaminants aboard piloted space vehicles. Emission of gases by polymers in electrical equipment starts with heating temperature rise to 100 degrees C. A new odour smelled by only some of humans due to individual perception signifies typically that emitted gases are below MAC for space vehicle. Odour sensed by everyone though not irritating signifies, as a rule, of chemical contamination above MAC but not contingency. Symptoms of irritation by products of thermal destruction of polymers signify contingency and require the use of personal protection equipment.