Biomedical subjects
Publications and source records attributed to B I Davydov.
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In experiments on 159 sexually mature dogs with an average weight of 6.5 + 0.71 kg, a study was made of the dynamics of physiological indices (rectal temperature, respiration and heart activity) of heat stress and various (%) effects of damage depending on power density (500, 300, 100 mV/cm2) and duration of microwave irradiation (2400 MHz). On the basis of the data obtained, it was established that the relationship between power density and duration of microwave irradiation with an equally probable (0.1%) effect of damage may be interpolated (100 < power density < 500) by an exponential equation of the type y = 1416 x-0.8156, where y = power density, mV/cm2, and x is the time of irradiation in minutes. The probability characteristic of adaptation possibilities of functionally critical values of damage not exceeding the indeterminate probability is obtained.
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In order to clarify mechanisms of biological reactions, it is very important to study the absorption and spatial distribution of the absorbed electromagnetic energy. The procedures and methods of calculating the electromagnetic energy absorption of biological specimens exposed to nonionizing electromagnetic irradiation in a wide frequency range (0-300 GHz) are described. Also presented are formulas and plots to be used in calculating the specific absorption of the dose rate by biological specimens, with the inclusion of resonance absorption, polarization of the incident electromagnetic wave, presence of reflecting surfaces and grounding. The extrapolation of the average energy absorption from one animal species to another and to man is discussed, assuming that spatial and energy distributions are equivalent. The notion of the irradiation quality coefficient is introduced. The magnitudes of the coefficients are given as related to the irradiation frequency and polarization type. A mathematical relation is offered to determine the safety of a complex spectrum of electromagnetic irradiation. The relation takes into consideration different dimensionality of the parameters of the electromagnetic field in the low- and high-frequency ranges.
This paper presents data on vomiting as a primary dose-dependent reaction of dogs to irradiation. It is shown that vomiting can be predicted with reference to the average absorbed dose in the abdominal area, provided the animal is irradiated in a lethal dose and the area is shielded. It is emphasized that calculated and experimental data are in good agreement.
A new experimental model of two conflicting motives has been developed and tested on rats. The motives are to escape painful stimulation and subsequent microwave irradiation at a dose rate of 500 mWt/cm2 under normal conditions and disturbed thermal regulation due to gamma irradiation of the head. It is found that microwave effects cannot be entirely attributed to the body temperature gradient.
The literature data are used to analyze the hygienic situation when man is exposed to constant electrical and low frequency electromagnetic radiations. The spectral characteristics and intensities of electrical fields near and on the surface of the Earth generated by natural sources of electromagnetic radiations (electrical quasi-static fields, atmospheric electricity, thunderstorm charges, electromagnetic radiation emitted by the sun and galaxies) are given. They can be employed to determine man's adaptive capabilities to the frequencies described during acute and chronic irradiation. The mechanisms of biological effects of the exposures are discussed. The methods for calculating the safety levels based on the USSR radiation safety standards and the "competing frequencies" procedure proposed can be applied to the design of electrotechnical devices and evaluation of integral hazard of constant electrical and electromagnetic fields of low frequencies.
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Protective properties of radioprotectors from indolyl alkylamine group (mexamine and indralin) in rats exposed to powerful electromagnetic irradiation (2.4 GHz, specific absorption rate 90-100 W/kg) was studied. The survival index of tested animals reached the maximum in condition of prophylactic administration of drugs in intervals 20-60 minutes before irradiation. Protective effect of mexamine and indralin connected with hypothermia and desensitization conditioned by the drugs use.
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Complexity and contradictoriness of the triplet life quality-health-risk gain particular acuity owing to the extensive and intensive nature of radiation and non-radiation risks in the modern technological society. Improvement of life standards issue new risks. Unavoidability of existing risks, emergence of new ones, and necessity of qualitative, first of all energetic, life maintenance come into conflict with the principles of ecological stability. The concept of life quality is in many respects irrational and in the future will largely hinge on traditions, ideological and religious maxims.
Qualitative analysis did not reveal changes in the blood forming system in pilots subjected to admissible doses of ionizing radiation. Quantitative evaluation of hemogram using the integral coefficient of deterioration of blood indices and differential blood count entropy index allowed to establish correlation between shifts in blood and dose rate. Hematologic changes, particularly in oxidative enzymes of platelets, to a large extent depend on the whole complex of factors characteristic of the Chernobyl accident. After 5 years since that tragedy the number of formed elements of pilots blood did not exceed their specific limits.
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