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Biomedical subjects

A O Korotkevich

Publications and source records attributed to A O Korotkevich.

At least 19 recordsLinked to original sources
PubMed2004

Weak turbulent Kolmogorov spectrum for surface gravity waves.

We study the long-time evolution of surface gravity waves on deep water excited by a stochastic external force concentrated in moderately small wave numbers. We numerically implemented the primitive Euler equations for the potential flow of an ideal fluid with free surface written in Hamiltonian canonical variables, using the expansion of the Hamiltonian in powers of nonlinearity of terms up to fourth order. We show that because of nonlinear interaction processes a stationary Fourier spectrum of a surface elevation close to <|eta(k)|(2)> approximately k(-7/2) is formed. The observed spectrum can be interpreted as a weak-turbulent Kolmogorov spectrum for a direct cascade of energy.

Journal Article↗
PubMed2000

[Dynamics of the non-specific reactivity of the organism in time].

Experiments with 10 mongrel rats and dogs showed that individual reactivity of animals to hypobaric hypoxia was same during repeated exposure in two weeks. Investigations of 20 dogs demonstrated relatively permanent types of group reactivity, i.e. hyper-, normal, and hyporeactivity to adrenaline injections every 2 months over a year period. Each type of group reactivity was marked by phase variation in the count of peripheral blood leukocytes with the relation of group mean values unchanged. Analysis of mean values of adaptive levels in 340 subjects with varying individual reactivity over 10 years also pointed to undulation of these values in each group. At the same time, the difference in mean values of this parameter among the groups was kept constant. Hence, the group specific reactivity has a long-range character as determined by testing.

Adaptation, Physiological↗
PubMed2000

[Individual radioresistance and principles of its formation].

Individual variability of resistance to a broad range of ionizing radiation was analyzed. Individual radioresistance depends both on physical (radiation type, dose, and distribution along the body, dose rate) and biological (species, strain, sex, body mass of animal etc.) factors. Individual radioresistance is manifested by specific and nonspecific responses of organism to radiation. Three components of individual radioresistance are stable, semistable and labile. The stable component is genetically determined by species, sex, habitus status and radiosensitivity of cells of critical organs. The semistable component is determined by embryogenetic, early postnatal development and reflected in functional activity of the main regulatory systems of the body. The labile component is a parameter of current functional state of an indviduum. The stable and semistable components characterize inborn whereas the labile component--acquired radioresistance.

Animals↗
PubMed1986

[Endocrine status in the prognostication of individual radiation sensitivity].

Experiments on rats dogs and monkeys demonstrated a high prognostic value of the direct adrenocortical activity index--the level of glucocorticoids in the blood (the accuracy of prognosis was 80-85%). The employment of overall comprehensive evaluation of the endocrine status for a number of indices to predict individual radiosensitivity was shown to hold promise.

Animals↗
PubMedDate not supplied

[Quantitative regularities for clinical manifestations of radiation injury in large-sized laboratory animals exposed to supralethal radiation doses Gamma-neutron and electron biological effectiveness as influenced by exposure conditions and dose distribution in the animal body].

The damaging effect of gamma-neutron radiation over a wide neutron-energy range, with average values of 0.37 and 1.2 MeV, and that of electrons with an average electron energy of 25 MeV have been compared in dogs and two monkey species exposed to a broad range of supralethal doses. An analysis of absorbed dose distribution in critical organs and systems has shown the highest effect of gamma-neutron radiation with an average neutron energy of 1.2 MeV. With severity of early clinical manifestations of damage as a criterion, electrons have appeared the most effective. The radiosensitivity of animals grew in the order as follows: dog-->M. fascicularis-->P. hamadryas.

Animals↗
PubMedDate not supplied

[Estimation of the individual radioresistance based on various parameters of the initial state of the body regulatory systems in animals].

The possibility of predicting the individual radiosensitivity of rats with the aid of a logarithmic index, which characterizes the initial state and quality of regulatory systems, is demonstrated. The index is calculated on the basis of some parameters of endocrine status before irradiation, such as corticosterone concentration and the ratio of potassium and sodium ions in the blood of experimental animals.

Algorithms↗
PubMedDate not supplied

[A possibility to predict the severity of individual damage following the exposure to supralethal radiation dosage. Prediction by early radiation response ].

The experiments on dogs and monkeys have shown that the severity of radiation sickness following the exposure to supralethal radiation doses can be predicted by early response of an individual. For such prediction, the most informative criteria include general severity of clinical manifestations during primary radiation response and evaluated within a few post-damage hours, the degree of tension in cardiac rhythm control, the cortisol level, the endocrine status index.

Animals↗
PubMedDate not supplied

[A possibility to predict the severity of individual damage following the exposure to supralethal radiation dosage. Prediction of working capacity of irradiated rats and dogs by response to pre-exposure physical load].

The experiments on rats and dogs exposed to radiation doses which cause intestinal and cerebral forms of radiation sickness have shown that, within the first 24 hours post-exposure, efficiency impairment can be predicted by changes in some indices of the cardiovascular and endocrine systems after physical load used as a non-radiation testing agent. The goodness of fit of experimental data to the expected result is up to 50-70%, still rising if a number of indices for different sections of the neuroendocrine system are used at a time.

Animals↗
PubMedDate not supplied

[A possibility to predict the severity of individual damage following the exposure to supralethal radiation dosage. Prediction of the clinical manifestation of radiation injury in laboratory animals by response to pre-exposure hypobaric hypoxia].

The experiments on rats, dogs and monkeys exposed to radiation doses which cause intestinal and cerebral forms of radiation sickness have shown that the severity of a clinical state can be predicted by cardiovascular and endocrine changes when a pre-exposure test with moderate hypobaric hypoxia is performed. The goodness of fit of experimental data to the exposed result is up to 60-80%, still rising if a set of indices of the neuroendocrine status is used.

Animals↗
PubMedDate not supplied

[A possibility to predict the severity of individual damage following the exposure to supralethal radiation dosage. Prediction of working capacity of irradiated rats and dogs by response to pre-exposure hypobaric load].

In experiments on rats and dogs exposed to radiation doses which cause intestinal and cerebral forms of radiation sickness, hypobaric hypoxia used as an unconventional test of animals' reactivity has enabled the relationship between reactivity and radiosensitivity to be established. Higher post-radiation efficiency is observed in animals with less pronounced changes during a barotest. The goodness of fit of experimental data to the expected result is up to 70%, rising if a set parameters for one index or the sum total of indices are used.

Animals↗
PubMedDate not supplied

[Prediction of the severity of damage and disruption of work ability in reaction of the body to alcohol load prior to radiation exposure in the superlethal range].

In experiments on 121 white non-linear rats, 44 Papio hamadryas and 29 Macaca fascicularis, animals' reactions on the alcohol impact (AI) and following exposure to supralethal doses were compared. The animals were intravenously injected with 5% ethanol in the glucose solution, 2.1 g/kg for rats and 0.46-0.51 g/kg for monkeys. Monkeys' response to AI was scored in four-point scale by estimating of abnormalities in motor activity, coordination of motion and changes in conditioned reflex activity. It was shown that changes in the ability of alcohol-injected rats to perform the learnt exercises in the "jump box" could be used for prediction of their response to the exposure to supralethal doses of ionizing radiation. Observing the AI-response in monkeys along with a method "function of spying for moving object" made possible to predict not only a general degree of loss of working ability but also to estimate individual impairments of spying functions. In 65% monkeys high similarity of the reactions to AI and ionizing radiation was observed.

Alcohols↗
PubMedDate not supplied

[Reaction of the blood forming system of the dogs to acute radiation exposure (by the SRC-Institute of biophysics data bank)].

At present time in the SRC--Institute of Biophysics the data bank containing the information on the reactions of 431 dogs to radiation exposure in a wide range of doses has been created. By the results of 4299 blood tests reporting a leukocyte content, including 2509 tests reporting a blood formula, the individual peculiarity of the peripheral blood reaction in dogs were analyzed. Dose dependencies for the reaction of blood-forming system to radiation exposure to doses in the range from 1.0 to 7.0 Gy were obtained. In comparison with the similar data for humans, the neutrophil content in peripheral blood decreased approximately 1.5-2.0 times faster in dogs than in men, resulting in earlier recovery.

Animals↗
PubMedDate not supplied

[Changes in the dog endocrine system in the hematopoietic form of radiation sickness].

The endocrine status of the organism estimated by the cortisol, insulin and triiodothyronine content of blood considerably changes during radiation sickness. The most pronounced changes in the endocrine status occur during the primary response and at the height of radiation sickness. The endocrine status test may be used in the individual radiosensitivity prognosis.

Animals↗
PubMedDate not supplied

[Evaluation of the possibility of prognosticating the individual radiosensitivity of rats from their reaction to hypoxia and administration of ACTH].

Experiments were carried out on male rats exposed to hypoxia and treated with adrenocorticotropin. Determinations were made of the resistance to hypoxia, gas exchange, and also the concentrations of corticosterone, K, Na and the amount of leukocytes in peripheral blood. The prognostication according to these parameters allowed to predict the outcome of radiation sickness with the accuracy of 68-82%. The corticosterone parameters have proved to be the most informative ones.

Acclimatization↗