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Biomedical subjects

V S Tikhonchuk

Publications and source records attributed to V S Tikhonchuk.

At least 19 recordsLinked to original sources
PubMed1992

[The possibilities for using new integral indices of the human peripheral blood].

In medical examination of flight personnel two new statistic indexes of integral estimate of changes in peripheral blood were used: integral blood deterioration ratio and entropy of leukocyte blood formula. These indexes have a rather high sensitivity that makes it possible to determine the tendency towards pathological changes in the organism, even if the whole blood picture will be within acceptance limits.

Blood Cells↗
PubMed1988

[Ultrastructure of the cerebral cortex in the rat after the effect of electromagnetic impulse].

In mature rats an area on the head has been subjected to a single radiation for 1.5 sec with microwaves in the continuous regimen of generation, frequency 2.4 GHz level of the specific absorbed power 5 W/g, that is accompanied with appearance of convulsions. Under anesthesia specimens of the superficial layer of the cerebral superlateral part are taken and subjected to electron microscopical investigation. Immediately after radiation and in 2 h certain disorders in microcirculation and reactive changes of mitochondria in perikaryons, axons, dendrites, synapses of the neurons and in gliocytes are revealed. The mitochondrial changes are designated as "edematous". In 2 and 6 h in karyoplasm of some neurons membranous structures appear; they are interpreted as a result of heat denaturation of the nuclear proteins. In synapses, together with lesions of mitochondria, synaptic complexes undergo destruction and osmiophilic substance is accumulated in the subsynaptic zone along the whole length of the contact. In one day, essential destructive changes are revealed as severe lesions of some neurons, vacuolization and destruction of mitochondria, localized in all the structures. Pathogenesis of the neurological disturbances is based on disturbances of interneuronal interactions, connected with an immediate heat effect of the electromagnetic radiation on the structures responsible for the synaptic transmission and with a rapidly developing tissue hypoxia as a consequence of microcirculatory disturbance and a sharp inhibition of energetic metabolism.

Animals↗
PubMed1979

[Effects of injurying and restoring the body of rats with microwave (2400 MHz) irradiation].

In experiments on 2072 rats the thresholds of power density (PD) and the duration of microwave irradiation were obtained with the effect of destruction not more than 0.1%. The speed ratio of formation processes of destruction and regeneration depends on power density of microwave radiation and interpolates the exponential function. Previously obtained (from experiments on mice) and now published data allow the eifference to be established between mice and rats as species. Mice are more sensitive from the standpoint of time of achieving equal effects of destruction, half and full period of regeneration, the speed ratio between destruction and regeneration depending on PD of microwave radiation.

Animals↗
PubMed1979

[Effects of injurying and restoring the body of mice with microwave (2400 MHz) irradiation].

In the experiments on 2200 mice the thresholds of powder density (PD) and time of irradiation were defined, when the death level did not exceed 0.1%. Dependence between the speed ratio of the destruction/regeneration and PD approached the exponential function. The functional dependences obtained quantitatively characterize the adaptive abilities of the mouse organism exposed to microwave irradiation.

Animals↗
PubMed1978

[Recovery responses in the bodies of rats following irradiation with microwaves (2400 MHz)].

During microwave irradiation (SHF-field, 2400 Mc/s) of rats in the range of capacity density of from 100 mW/cm2 to 800 mW/cm2 the function of regenerative effect and the time interval between the irradiation cycles (power densityconst) approximates the logistic one, whereas that of the power density and the time interval between the irradiation cycles (regeneration level = const) approximates the linear one.

Animals↗
PubMedDate not supplied

[The characteristics of the action of ethanol in operators with different states of the skin tissue basophils].

The changes in some parameters of an operator activity after ethanol administration at a dose of 1.9 g/kg body weight in 10 men doing the job of two-dimensional compensatory tracking in simulator, have been studied. In this case, the population state of tissue basophils (mast cells) of the body by studying the amounts of various structural and metabolic forms of these cells, contained in the skin biopsies, was studied. The degree of deterioration in operator activity was evaluated separately for the subjects with the population characteristics of tissue basophils higher or lower than mean values. It is indicated that the subjects with a low initial number of tissue basophils exhibiting signs of a holocrine-typed secretion and with a more pronounced response of these cells to ethanol were characterized by a significantly higher degree of the impairing many parameters of operator activity. Such differences were especially marked immediately after ethanol administration and practically lacked 12 hours after.

Adult↗
PubMedDate not supplied

[Microwaves and the visual analyzer].

The results of studying an effect of microwaves on the different regions of visual analyzer are investigated. The morphofunctional changes at the light-optic and electron-microscopic levels are revealed. The changes involve not only peripheric area of visual analyzer but also its central regions. Some epidemiologic observations are indicative of: altered sizes of blind spot; decreased magnitudes of optic rheobase and chronaxy; color vision disorder; increased diastolic pressure in central artery of the retina. Study of bioelectrical activity of the retina enabled some investigators to make a conclusion about a reaction disorders occurring in the subcortical visual centers. It is noted that the animal studies not always explain unequivocally the microwave effects on the visual analyzer.

Animals↗
PubMedDate not supplied

[Neuropharmacological reactivity of the body exposed to extreme factors: the effect of radiation].

The functional state of neurochemical structures of male mice was investigated after their gamma-irradiation with 137Cs (1.9 Gy/min) at a dose of 100 Gy. The animals were treated with the following drugs that produce selective effects on specific receptors: galanthamine (0.5 mg/kg), amizyl (30 and 60 mg/kg), arpenal (30 mg/kg), phenamine (3, 6 and 10 mg/kg) phentolamine and obsidan (1 mg/kg), haloperidol (0.5 and 1 mg/kg), apomorphine (2 mg/kg), phenazepam (0.05 and 2 mg/kg), phenibut (200 mg/kg), and strychnin (0.1 and 0.2 mg/kg). The physical performance of the animals was measured with the aid of a swimming test applied 2 and 6 hours after irradiation. The results point to the development of heterologous desensibilization of receptors at early post-irradiation periods. The high effectiveness of agonists and antagonists of CNS transmitters in the nonirradiated animals and their low effectiveness in the irradiated animals may be considered as an indicator of post-radiation injury of specific receptors. This seems to be responsible for partial or total resistance of irradiated animals to the regulatory effects of neurotransmitters. These neuropharmacological interactions may obviously be modified in response to the combined effects of space flight factors.

Animals↗
PubMedDate not supplied

[Effect of urea and pituitrin on cerebral radiation effects in rats].

The administration of urea and pituitrin produced a directed and rapid change in a hydration profile of brain tissue which permitted to modify the severity of cerebral radiation affection in rats, that is, to increase it with hypohydration and to decrease with hyperhydration of the brain.

Animals↗
PubMedDate not supplied

[Epidemiologic studies of the effect of microwaves (neurophysiologic, hematologic and ophthalmologic aspects)].

This paper presents epidemiological and clinical evaluations of subjects exposed to electromagnetic radiations (EMR) in the microwave range with emphasis on neurophysiological, hematological and ophthalmological changes. Special attention is given to neurological and psychogenic effects of EMR as well as to possible development of radiophobia. Ageing, cataract development and genetic signs are considered as objective measures of EMR effects.

Action Potentials↗
PubMedDate not supplied

[A multifactorial study on the relative postradiation changes in various categories of behavioral reactions in rats].

The use of the methods of multifactor, orthogonal and composition planning in studying the behavioural disturbances in rats after gamma irradiation with doses of 0.258 to 1.29 C/kg and the application of the proposed method of discrimination of effects by empirical models permitted to establish the informative and adequate dependences of the probability of these disturbances on dose of nonuniform irradiation and the degree of strengthening of the conditioned reflex. It was shown that the effect of radiation decreased, in a discrete manner, the probability of making the first decision by rats in a behavioural task (here we deal with the "dose-response" function). The average time of making the first decision after irradiation was invariable within the dose range under study. Within the range of the studied factors both the value of the dose of whole-body irradiation and the degree of strengthening of the conditioned reflex significantly affected the probability of fulfilling the task by the animals the significance of the radiation dose being several times higher. The effects of the interaction of the two factors, that is, irradiation and the degree of the radiation affection, were insignificant in changing the behavioural reactions under study.

Animals↗
PubMedDate not supplied

[Status of the synapses of the end brain of rats exposed to the factors of space flight].

Using electron microscopy, synapses of different structures of the rat end brain related to cognitive and motor acts (sensorimotor cortex, caudate nucleus) as well as memory and behavior (hippocampus) were examined. Rats were exposed to ionizing radiation, super-high frequency, hypoxia, hyperoxia, vibration and acceleration (applied separately or in combination) which have been traditionally in the focus of space and aviation medicine. Brain interneuronal junctions were found to be very sensitive to the above effects, particularly ionizing radiation and hypoxia. Conversely, synapses were shown to be highly resistant to short-term hyperoxia and electromagnetic radiation. When combined effects were used, responses of interneuronal junctions depended on the irradiation dose and order of application of radiation and other flight factors.

Acceleration↗
PubMedDate not supplied

[Structural and metabolic analysis of the reaction of the central nervous system to the combined action of microwave and ionizing radiations].

Structural and functional changes in the central nervous system were shown to be the same with both microwave and ionizing radiation having different mechanism of action. When the two types of radiation were delivered in a combination the sequence of delivery was of a significant importance. Antagonism of the effects was noted when microwave radiation was delivered prior to gamma-radiation. The effect was synergistic when the exposure to microwaves followed gamma-irradiation.

Animals↗
PubMedDate not supplied

Heat stress in microwave irradiation.

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.

Animals↗