The effect of low-dose rate radiation simulating the high-altitude flight conditions on mice in vivo

In present work, we investigated the peculiarities of the effect of a low-dose rate high-LET radiation that simulates the spectral and component composition of the radiation field formed in the atmosphere at a height of 10 km on mice in vivo. The dose dependence and adaptive response were examined. Irradiation of mice was performed for 24 h a day in the radiation field behind the concrete shield of the Serpukhov accelerator of 70 GeV protons for the time (15-31 days) necessary to accumulate the required doses. The experiments demonstrated that irradiation of mice in vivo in the dose range of 11.5-31.5 cGy leads to an increase in cytogenetic damage to bone marrow cells and induces no adaptive response in bone marrow cells.     

The remote effects of radiation after hypofractionated irradiation with protons of Ehrlich ascites carcinoma in mice

This work focuses on the study of remote effects (duration of remission, recurrence rate, and average lifespan) in mice with Ehrlich ascites carcinoma exposed to oligofractionated irradiation with a pencil scanning beam of protons depending on the volume of the tissue being irradiated and the interval between dose fractions. The results show higher antitumor efficacy and a considerable increase in the average life span of mice after hypofractionated irradiation with a pencil scanning beam of protons at a total dose of 60 Gy of the gross tumor volume compared with the planning target volume.     

The combined effects of dietary supplements and low-dose-rate high-LET radiation on mice in vivo

The purpose of this study was to investigate the combined actions of food supplements and lowdose-rate high-LET radiation on radiosensitivity, induction of the adaptive response, and tumor growth in SHK mice in vivo. The animals were irradiated with 0.11 Gy (0.005 Gy/day) of low-dose-rate high-LET radiation behind the concrete shield of a 70 GeV proton accelerator (Protvino, Moscow oblast). Four groups of the mice were fed with selected products (soy meat, buckwheat, lettuce leaves, and a drug based on cod-liver oil) during the entire irradiation period (22 days). The results of the study indicate that the mice with diets containing soy meat, buckwheat, and lettuce leaves in contrast to those fed with a diet containing cod-liver oil had reduced sensitivity to X-radiation at a dose rate of 1.5 Gy and a significant slowdown in the growth of the Ehrlich carcinoma. The combined effect of high-LET radiation and the food supplements mentioned above (except for the cod-liver oil) reduced the sensitivity of the mice to the irradiation at a dose rate of 1.5 Gy, induced the adaptive response, and caused a decrease in the growth rate of the Ehrlich carcinoma in contrast to the mice that were only irradiated with high-LET radiation.     

Peculiarities of the effect of low-dose-rate radiation simulating high-altitude flight conditions on mice in vivo

In the present work, the effect of a low-dose rate of high-LET radiation in polychromatic erythrocytes of mice bone marrow was investigated in vivo. The spectral and component composition of the radiation field used was similar to that present in the atmosphere at an altitude of about 10 km. The dose dependence, adaptive response, and genetic instability in the F₁ generation born from males irradiated under these conditions were examined using the micronucleus test. Irradiation of the mice was performed for 24 h per day in the radiation field behind the concrete shield of the Serpukhov accelerator. Protons of 70 GeV were used over a period of 15–31 days, to accumulate doses of 11.5–31.5 cGy. The experiment demonstrated that irradiation of mice in vivo in this dose range leads to an increase in cytogenetic damage to bone marrow cells, but does not induce any adaptive response. In mice pre-irradiated with a dose of 11.5 cGy, an increase in sensitivity was observed after an additional irradiation with a dose of 1.5 Gy. The absence of an adaptive response suggests existence of genetic instability.     

Hypofractionated irradiation of the solid form of Ehrlich ascites carcinoma in mice by a thin scanning proton beam

The dynamics of the growth of Ehrlich ascites carcinoma in mice of the SHK line exposed to hypofractionated high-dose irradiation by a thin scanning proton beam has been analyzed for different irradiation volumes and different time intervals (from 4 to 24 hours) between two 30-Gy fractions. Irradiation of the gross tumor volume and the planned target volume was performed within the Bragg peak; the energy of protons at the outlet of the accelerator ranged from 85 to 100 MeV. Hypofractionated irradiation of the gross tumor volume of Ehrlich ascites carcinoma resulted in a more pronounced antitumor effect than the irradiation of the planned target volume. The effect did not depend on the interval between the irradiation episodes.     

The effect of infrared and X-ray radiation on the production of reactive oxygen species in blood and induction of cytogenetic damage in the bone marrow of mice in vivo

The goal of the present work was to study the effect of infrared light (IRL) at a wavelength of 850 nm modulated by a frequency of 101 Hz with a mode of power 22 mW/cm2 and X-rays with a voltage of 200 kV at a dose rate of 1 Gy/min on the production of reactive oxygen species (ROS) in blood cells using luminol-dependent chemiluminescence, as well as on the induction of a cytogenetic damage in bone marrow cells of mice by the in vivo micronucleus test. The experiments performed have shown: 1) the level of the ROS production in blood of the mice exposed to IRL and X-rays at an adapting dose of 0.1 Gy reaches the peak value after 0.5 h and drops to the ROS level in untreated animals 5 h after either exposure; 2) irradiation of mice with IRL and X-rays at a dose of 0.1 Gy induces adaptive responses both in blood cells and bone marrow cells of mice. These adaptive responses were revealed only 5 h after both exposures, when the level of ROS production decreased to the ROS level in untreated animals; they are equal in magnitude and dynamics and persist up to 2 months.     

Influence of low-dose-rate red and near-infrared radiations on the level of reactive oxygen species,the genetic apparatus and the tumor growth in mice in vivo

The effect of low-dose-rate red and near-infrared radiations from the matrix of light emitted diode (650 nm and 850 nm) and a He-Ne laser (633 nm) on activation of the reserve of a natural defense system in the mice exposed to radiation in vivo was studied by the level of reactive oxygen species (ROS) production in blood cells, the induction of cytogenetic adaptive response in bone marrow cells, thymus and spleen, and the rate of Ehrlich ascites carcinoma growth in a solid form. As a positive control animals were irradiated with X-rays by the scheme of the radiation-induced adaptive response (0.1 Gy + 1.5 Gy). The levels of ROS production was assessed in whole blood by luminol-dependent chemiluminescence, of cytogenetic damage — by the “micronucleus test” in the bone marrow, the weight of the thymus and spleen — by index of organ, and the rate of tumor growth — according to its size for 30 days after inoculation. Adaptogenic and anticarcinogenic effects of studied radiations were revealed. The values of these effects were not different from those in animals pre-irradiated with the X-rays. The relationship between the level of ROS production and adaptive response induction in the mice under the influence of non-ionizing radiation was first ascertained. The experimental data obtained may indicate a similar mechanism of induction of protective responses to ionizing and non-ionizing radiations in mice in vivo.     

Transgenerational genomic instability in the first generation offspring of mice exposed to low-intensity red and near-infrared irradiation in vivo

Transgenerational genomic instability in the first generation offspring of mice exposed to lowintensity infrared laser (632.8 nm) and light-emitting-diode infrared irradiation (850 nm) was investigated in vivo. It was found that the level of spontaneous damage in bone marrow according to the micronucleus test, the level of reactive oxygen species in whole blood, and the mass index of lymphoid organs in all of the descendants of irradiated mice did not increase. After additional X-ray exposure of the progeny at a dose rate of 1.5 Gy, a decrease in the level of damage and the absence of an adaptive response were revealed upon testing according to “radiosensitivity” and the radiation-induced adaptive-response scheme (0.1 + 1.5 Gy), respectively, compared to the descendants of nonirradiated mice. The rate of tumor growth in the offspring of irradiated mice did not differ from that in the descendants of nonirradiated mice, although inhibition of the tumor growth rate was observed in their irradiated parents. The survival rate after irradiation at a dose rate of 6.5 Gy did not differ from both the parents and the control.