Quantitative characteristics of radiation injury of the spermatogenic epithelium and the rate of its recovery after exposure to fast neutrons and gamma-radiation

The paper submits the results of studies on the kinetics of spermatogenous epithelium cell number after exposure to fast neutrons (60-300 cGy) and gamma-radiation (200-600 cGy). It was shown that a relative decrease in the quantity of spermatocytes is determined by an exponential dose-response curve with D0 of 35 and 120 cGy for neutrons and gamma-radiation respectively. For spermatides and spermatozoa a single D0 value of 20 and 55 cGy was obtained for neutrons and gamma-radiation respectively. As the radiation dose increases the recovery process in the epithelium is substantially decelerated. The equation T1/2 = T1/2(0)e0.0009D well describes the dependence of the half-recovery period T1/2 upon the equivalent dose.     

Compensatory Reserves of the Human Body and Population Health under Conditions of Exposure to Chronic Anthropogenic Factors and Prolonged Psychoemotional Stress

Long-term exposure to adverse factors of various origin and intensity is expected to cause a significant decrease in the compensatory reserves and adaptive capacity of the human body. These changes deteriorate the population health status in general. A quantitative method of evaluation of the decrease in the compensatory reserves and adaptive capacity, as well as the resistance to chronic exposure to extreme factors of various origin and intensity, was developed. This method is based on the concept of stress and programmable nonspecific physiological reactions of the human body put forward by H. Selye. Model analytical curves of the time-related decrease in the volume of compensatory reserves and the increase in the probability of development of adaptive disorders and failure of the adaptation process were calculated for the cases of long-term exposure to various stressors (the factors were applied individually or in combination). This method allowed the levels of population health risk induced by various factors to be compared to each other. This is of particular importance under conditions of the existing trend toward an increase in the intensity of anthropogenic stress factors against the background of long-term psychoemotional stress. Statistical data on changes in the rates of morbidity and mortality and the life expectancy of Russian people for the period 1960–2000 were analyzed. The levels of risk of the negative impact on population health induced by various stress factors (radiation, chemical environmental pollution, and long-term psychoemotional stress) were compared to each other.     

Characteristics of the descendants of male dogs exposed to chronic combined gamma-irradiation and in the postradiation period

A study was made of the descendants of 12 male dogs subjected to gamma-irradiation during six years at dose-rates of 0.0034 Gy/day and 0.0017 Gy/day + additional annual exposures to gamma-radiation three times a year each of 0.42 Gy. The observations were made during 3 years after the end of irradiation. It was shown that the descendants reflected the regularities of the disorders revealed in fathers' spermatogenesis. The radiobiological effects were function of dose--rate and cumulative radiation dose. The changes were mainly noted during embryogenesis and manifested by the sterility, mortinatality and the decreased number of puppies in the postreity.     

Autoimmune processes after long-term low-level exposure to electromagnetic fields (experimental results) part 5. Study of the influence of blood serum from rats exposed to low-level electromagnetic fields on pregnancy and fetal and offspring development

The work evaluates the possible adverse effects on pregnancy and fetal and offspring development arising from the injection of blood serum from rats exposed to microwaves at a power density of 500 μW/cm² into intact female rats. The study is performed on 59 pregnant Wistar rats. Intrauterine mortality, embryo and fetal body weights, and placenta weight are used for the evaluation of embryo and fetal development. Generally accepted integral and specific parameters are used for the evaluation of the postnatal development of offspring during the first 30 days of life. It is shown that injection of blood serum from rats subjected to long-term RF exposure at 500 μW/cm² into intact rats on the tenth day of pregnancy results in adverse effects on fetal and offspring development. Higher total in utero and postnatal mortality, as well as delayed offspring development, are recorded.     

The method based on generalized dosimetric function for estimation of cosmonauts' radiation hazard during long-term space missions

This paper presents a method of assessment of radiation hazard for cosmonauts. The method is based on a new dosimetric function, which enables a complicated nature of space radiation exposure to be reduced to the condition of a standard irradiation on Earth. It can be obtained on the basis of mean-tissue absorbed dose values calculated for each space radiation source, and transmission coefficients. The transmission coefficients define relative biological effectiveness of radiation and assess the influence on the radiobiological effects of the complex spatial and temporal distribution of the absorbed dose in the cosmonaut's body. The combination of cosmic ionizing radiation with other non-radiation nature factors in flight can be accounted.     

Radiation injury of hemopoiesis in alpine conditions depending upon the duration of adaptation

A study was made of the disturbance of haemopoiesis in the small laboratory animals and dogs kept in Alpine conditions (3200 m) and exposed to ionizing radiation on days 3, 15, 22, 25 and 33 of adaptation. The radiation damage to haemopoiesis in Alpine conditions was shown to decrease at the beginning of the adaptation due to the intensification of the regenerating processes, which was manifested by the increase in the rate of DNA synthesis in the haemopoietic organs, and activation of erythropoiesis, myelopoiesis and lymphopoiesis. Later (after 30-35 days), a 2-4-fold increase was noted in the number of haemopoietic stem cells which improved the compensatory potency of the tissue under study and increased the total resistance of the organism.     

Confirmation studies of Soviet research on immunological effects of microwaves: Russian immunology results

This paper presents the results of a replication study performed to investigate earlier Soviet studies conducted between 1974 and 1991 that showed immunological and reproductive effects of long‐term low‐level exposure of rats to radiofrequency (RF) electromagnetic fields. The early studies were used, in part, for developing exposure standards for the USSR population and thus it was necessary to confirm the Russian findings. In the present study, the conditions of RF exposure were made as similar as possible to those in the earlier experiments: Wistar rats were exposed in the far field to 2450 MHz continuous wave RF fields with an incident power density in the cages of 5 W/m² for 7 h/day, 5 days/week for a total of 30 days, resulting in a whole‐body SAR of 0.16 W/kg. Effects of the exposure on immunological parameters in the brain and liver of rats were evaluated using the complement fixation test (CFT), as in the original studies, and an additional test, the more modern ELISA test. Our results, using CFT and ELISA, partly confirmed the findings of the early studies and indicated possible effects from non‐thermal RF exposure on autoimmune processes. The RF exposure resulted in minor increases in formation of antibodies in brain tissue extract and the exposure did not appear to be pathological. In addition, a study was conducted to replicate a previous Soviet study on effects from the injection of blood serum from RF‐exposed rats on pregnancy and foetal and offspring development of rats, using a similar animal model and protocol. Our results showed the same general trends as the earlier study, suggesting possible adverse effects of the blood serum from exposed rats on pregnancy and foetal development of intact rats, however, application of these results in developing exposure standards is limited. Bioelectromagnetics 31:589–602, 2010. © 2010 Wiley‐Liss, Inc.