Anti-tumor Effect of High Doses of Carbon Ions and X-Rays during Irradiation of Ehrlich Ascites Carcinoma Cells Ex Vivo

The effect of carbon ions (12C) with the energy of 400 MeV/nucleon on the dynamics of induction and growth rate of solid tumors in mice under irradiation of Ehrlich ascites carcinoma cells (EAC) ex vivo at doses of 5-30 Gy relative to the action of equally effective doses of X-ray radiation was studied. The dynamics of tumor induction under the action of 12C and X-rays had a similar character and depended on the dose during 3 months of observation. The value of the latent period, both when irradiating cells with 12C and X-ray, increased with increasing dose, and the interval for tumor induction decreased. The rate of tumor growth after ex vivo irradiation of EAC cells was independent of either dose or type of radiation. The dose at which EAC tumors are not induced within 90 days was 30 Gy for carbon ions and 60 Gy for X-rays. The value of the relative biological effectiveness of carbon ions, calculated from an equally effective dose of 50% probability of tumors, was 2.59.

Growth Induction of Solid Ehrlich Ascitic Carcinoma in Mice after Proton Irradiation of Tumor Cells Ex Vivo

This study presents data on the growth rate and frequency of induction of the solid form of Ehrlich's ascites carcinoma (EAC) in mice in the short and long term after inoculation of ascitic cells irradiated ex vivo with a proton beam in the dose range of 30-150 Gy. It was shown that the growth rate of solid tumors after inoculation of irradiated cells ex vivo coincided with the growth of tumors in the control group. The frequency of tumor induction in mice after inoculation of EAC cells irradiated at a dose of 30 Gy was 80%, 60 Gy-60%, 90 Gy-25%, and 120 Gy-10%; at irradiation at a dose of 150 Gy, no tumors appeared during the entire observation period. Thus, we determined the dose of proton radiation required to eliminate tumor cells and/or signaling factors that can lead to the induction of tumor growth of EAC in mice.

Radioprotective Effect of Nanocerium by Irradiation of Mice with Carbon Ions in Medium and Lethal Doses

The data of the study of the radioprotective properties of nanocerium (nCeO₂) after total irradiation of mice with carbon ions in medium and lethal doses according to the micronucleus test and the criterion of 30-day survival are presented. A significant protective effect of nCeO₂ upon irradiation at medium doses was observed at per os administration for 5 days before irradiation (that is, at long-term prophylactic use). Mouse survival data showed no protective effect of per os administration of nCeO₂ in contrast to the micronucleus test results. After injections of both nCeO₂ and saline solution 24 h before or immediately after irradiation, the radioprotective effect was detected using both methods. The data obtained revealed the dependence of the observed effects on the mode and time of nCeO₂ administration, the influence of the solvent, the level of doses and the quality of radiation, as well as demonstrated the possibility of using nanocerium preparations to protect organisms from radiation with high LET values and the importance of further studies of the radioprotective properties of new nanomaterials.

Assessment of the Relative Biological Efficiency of Pencil Beam Scanning of Protons in Mice in Vivo

The effect of proton pencil beam scanning in the dose range of 4.5-15 Gy on the radiosensitivity of mice under irradiation in two regions of the Bragg curve was studied according to the criteria of 30-day survival, dynamics of death, and average lifespan of mice. The relative biological effectiveness (RBE) value of protons relative to X-ray radiation before and at the Bragg peak determined by the LD_50/30 index was 0.86 and 0.94, respectively, and by the criterion of 30-day survival at a dose of 6.5 Gy it was 0.83 and 0.84, respectively. With similar RBE values for protons in different regions of the Bragg curve, significant differences in the dynamics of the course of radiation sickness were revealed, which indicates different damage to critical systems and organs of animals and the induction of compensatory mechanisms involved in the formation of stress responses at the organismal level.

Combined Effect of Neutron and Proton Radiations on the Growth of Solid Ehrlich Ascites Carcinoma and Remote Effects in Mice

The combined effect of the irradiation with a proton pencil scanning beam (PBS) at a total dose of 80 Gy and neutron radiation at a dose of 5 Gy on the growth of solid Ehrlich ascites carcinoma (EAC) and the remote effects in tumor-bearing mice was studied. Combined irradiation of mice with neutrons before and after irradiation with PBS, as well as irradiation only with PBS, effectively suppressed the growth of solid EAC within 1 month. In terms of the frequency and severity of radiation-induced skin reactions of mice observed 15-40 days after therapy, neutron irradiation after the irradiation with PBS showed better values of these parameters as compared to only PBS; however, exposure to neutrons before PBS was more damaging as compared to the other two options. It was also shown that the tumor relapse rate in the groups of animals with combined irradiation was higher, and the total lifespan was lower than the group of mice irradiated with PBS alone.

The Effect of Low and Medium Doses of Proton Pencil Scanning Beam on the Blood-Forming Organs during Total Irradiation of Mice

The aim of this work was to study the effect of proton pencil beam scanning in the Bragg peak in the dose range of 0.1-1.5 Gy on the induction of cytogenetic damage in the bone marrow, reactive oxygen species (ROS) production in whole blood, and the state of lymphoid organs after total body irradiation of mice. Irradiation was carried out in the Prometeus proton synchrotron (Protvino) in the Bragg peak with proton energy at the output of 90-116 MeV. It was found that, under irradiation of mice in the range of low and medium doses of proton pencil beam scanning in the Bragg peak, the relative biological effectiveness (RBE) according to the criterion of cytogenetic changes was 1.15. In addition, it was found that the pathophysiological effect on the lymphoid organs and the production of ROS by blood cells were different as compared with the effect of X-rays.