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Biomedical subjects

L P Zhavoronkov

Publications and source records attributed to L P Zhavoronkov.

At least 19 recordsLinked to original sources
PubMed2000

[The optimization of a plan for the photodynamic therapy of sarcoma M1 using photosens].

The study established the importance of optimal dosage, concentration and mode of administration of the drug Fotosens for the effectiveness of photodynamic therapy of tumor. Of similar importance is the interval between administration and irradiation to potentiate the drug's action. Failure to consider the latter factor may lower the effect dramatically or even reverse it. Experimental findings point to high antitumor potency of the drug. Preference should be given to injecting relatively low concentrations along the periphery of tumor, thus avoiding the undesirable cytostimulating effect and toxicity of Fotosens and saving on the drug. The potential of the treatment as a component of "white light" photodynamic therapy is discussed.

Animals↗
PubMedDate not supplied

[Biological effects of the low-intensive laser of the near infra-red spectrum].

The immediate and the remote effects of the total one-time uniform irradiation with arsenid-hallium laser (wavelength 0.89 mu, pulse power 450 W, pulsed mode 80-3000 Hz) on the new-born Wistar rats have been examined. The complex of tests illustrated the biotropical effects of used laser regimes. The stimulating or braking of the animal's growth was observed in accodanse with the laser regime.

Animals↗
PubMedDate not supplied

[Experimental estimation of thermogenic levels of acute microwave exposure for different animal species].

In experiments on laboratory animals it was found the different patterns of reactions in response to acute thermogenic 7 GHz CW microwave exposures. The effects were related specifically to the intensity of the field. SAR equal 0.5-0.7 power of basal metabolism of different species did not result in increase of body temperature. At SARs over intensity of basal metabolism (up to 1.5-2.0 basal metabolism for the mice and for the rats and up to 1.5 for the rabbits) the "stepped" pattern of body heating with periods of rectal temperature stabilization was observed. This results may have implications for prognostic estimation of dose-temporal limits of endurable intensities of microwaves.

Acute Disease↗
PubMedDate not supplied

[Dependence of microwave effect on the secondary structure of DNA on molecular weight of polynucleotide].

The effect of ultralow power pulse-modulated electromagnetic radiation (average power density 60 microW/cm2, carrying frequency 1.05; 2.12; or 2.39 GHz; modulating pulses with frequency 4 Hz) on the secondary structure of DNA was investigated. It was established that the exposure of beta-alanine and formaldehyde containing aqueous DNA solution to electromagnetic radiation had activated the process of DNA despiralization under the action of beta-alanine--formaldehyde reaction product. The effect of electromagnetic radiation on the secondary structure of DNA can be removed by lowering of molecular weight of DNA to 0.46 x 10(6) (at carrying frequency 1.05 GHz), or to 0.25 x 10(3) (at carrying frequency 2.39 GHz).

Animals↗
PubMedDate not supplied

[Effects of microwave radiation on conditioned behavior of rats].

Research has been carried out to investigate the effects of microwave exposure (7 GHz, surface energy density 10-50 mW/cm2, SAR 2.1-10.5 W/kg) on learned behaviors of rats in the paradigm of conditioned avoidance reflex. It was shown that transitory reductions in conditioned behavior after acute microwave exposure occurred at an SAR equal to the intensity of rat basal metabolism. It was found cumulative effects for intermittent exposures of rats at a power density of 10 mW/cm2.

Animals↗
PubMedDate not supplied

[The efficiency and direction of thymus changes after whole-body exposure of mice to the weak electromagnetic field are determined by the initial status of the thymus].

The work presents results of the experimental study on thymus changes developing after whole-body exposure of mice to ultralow power pulse-modulated electromagnetic field (carrying frequency 2.39 GHz, modulating pulses with frequency 4 Hz, duration of impulses 0.025 sec, average power density 60 mW/cm2, absorbed dose 0.086 J/g or 0.172 J/g). It was shown that a percent of the microwave induced increase or decrease of thymus mass and the number of cells in the organ (y) are determined by the initial mass or number of cells in thymus accordingly to equation of linear regression: (yx = 215-2.25x, where x is the thymus mass of control animals (in a range 31-63 mg) and (yx = 178.6-41x, where x is the initial number of cells in thymus (in a range 0.6 x 10(8)-2.6 x 10(8)) reduced by a factor of 10(8).

Animals↗
PubMedDate not supplied

[Effects of electromagnetic field of thermal intensity on the hypophysis-thyroid unit of the neuroendocrine system].

Acute 12-minute exposure of laboratory rats to microwaves with specific dose rate (SAR) of 30 W/kg that exceeded a basal metabolism caused a transient response of hyppophysis-thyroid system of compensatory-adaptive character. Prolonged exposure to microwaves of less intensity (SAR = 6 W/kg, which approximately corresponds to basic metabolic rate for these animals) caused insufficiency of the function of thyroid control in a form of primary hypothyroidis.

Animals↗
PubMedDate not supplied

[Comparative estimation of the effects of continuous and intermittent cyclical microwave radiation on the behavior of rats in the extraordinary situation].

Research has been carried out to investigate the effects of pulsed microwave exposure without pause (7 GHz, 400 pps, 100 microseconds, 70-150 mW/cm2, exposure 10 min) and pulsed interrupted cyclical microwave exposure (5 min exposure--4 min pause--5 min exposure) on learned behaviors of rats in the paradigm of extraordinary situation (the rescue of the life). It was shown that reductions in conditioned behavior after acute pulsed microwave exposure occurred at SAR of 21 W/kg (100 mW/cm2) and after cyclical pulsed microwave exposure at SAR of 28.4 W/kg (135 mW/cm2).

Animals↗
PubMedDate not supplied

[Effects of the microwave exposure at elevated ambient temperature on the thermo-compensatory responses of small laboratory animals].

Thermogenic effectiveness of electromagnetic irradiation (EMI) of UHF range (7 GHz) in the dependence on intensity (10-50 mW/cm2) and environmental temperature (22 degrees and 30 degrees C) was studied in experiments with mice and rats. Negative influence of high ambient temperature on thermoregulate responses of animals at microwave exposure was showed. It is concluded that this interaction should been taken into account for hygienic standardization of non-ionizing EMI.

Animals↗
PubMedDate not supplied

[Radiation-induced and embryotoxic effects in experimental hyperthyroidism].

The purpose of this article was investigation the development of the posterity rat (line Wistar) in the postnatal ontogenesis after combined and separate action of gamma-radiation (1.25 Gy at 20 days) and hyperthyroidism, provoked by toxic thyroid doses of 100 mg thyroidin per rat. It was shown that hyperthyroidism did not affect physical development of the irradiated posterity, but in a long-time period (7 month) it was revealed a decrease in ability to the training of posterity rats after the combined action of the factors.

Animals↗
PubMedDate not supplied

[The effect of pulsed cyclical microware radiation on the conditioned behavior of rats].

Research has been carried out to investigate the effects of pulsed cyclical microware exposure (7 GHz, 400 pps, 100 mcs, 10-20 mW/cm2, 10 or 20 cycles of "5 min exposure--4 min pause") on avoidance learning of rats. It was shown that reductions in conditioned behavior after cyclical pulsed microware exposure occurred at an SAR of 2.1 W/kg (10 mW/cm2). It was found the cumulation of the effects of the cycles at prolonged cyclical microwave exposures.

Animals↗
PubMedDate not supplied

[The influence of exogenous melanin on the development of female Wistar rats' posterity of first generation exposed to low doses at different dose rates during embryogenesis].

To research a radio-protective effect of melanin on the reproductive system during its creation the development of first generation posterity (900 descendants) of 125 pubertal female Wistar rats was examined after the single gamma-irradiation with a dose of 1 Gy (mean dose rate of 0.03 mGy/h), which they have been exposed to on the day ten of pregnancy, and the chronic gamma-irradiation with a total dose of 1 Gy (mean dose rate of 5.31 mGy/h) which they have been being exposed to during the first 10 days of pregnancy. The melanin of natural animal origin has the anti-radial effectiveness with the single irradiation increasing the number of alive newborn descendants in a litter and doubling their survival during the first 30 days after the birth. The melanin's effect is less expressed with the chronic irradiation.

Animals↗
PubMedDate not supplied

[Effect of the combined use of chemical radioprotectors and inhibitors of prostaglandin biosynthesis on the postradiation recovery of hemopoiesis in mice].

In experiments on mice it was shown that chemical radioprotective agents and inhibitors of prostaglandins, which were administered in a combination after irradiation to promote the haemopoiesis recovery, exerted a pronounced hemo-stimulating effect exceeding that produced by each of the agents applied separately and increasing the survival of mice.

5-Methoxytryptamine↗
PubMedDate not supplied

[Modification of the radiation injury of hematopoiesis in rats using the gaseous hypoxic mixture GHM-10].

In experiments on Wistar rats it was shown that gas hypoxic mixture containing O2 (10%) and N2 (90%) had a radioprotective action with regard to the survival rate for 30 days and to the haemopoietic system status. The application of gas hypoxic mixture reduced the postirradiation cytopenia in the blood and lowered the degree of the bone marrow depletion by the 3d day following irradiation; DMF was 1.25 as determined by total bone marrow cellularity.

Animals↗