[Radioprotective effect of hypoxic hypoxia (8% O2) for different morphological elements of mouse kidney].

The breathing of gas mixtures containing 8-9% O2 during irradiation of tumors has been tested at several cancer clinics (in Russia and abroad) with the purpose of decreasing the morbidity of normal issues, thus providing the possibility to increase the dose of radiation. Previous experiments have demonstrated a broad spectrum of dose modification factors (DMF) for different normal tissues as well as for different transplanted tumors, with in general larger protection of normal tissues. The present study was designed to assess the radioprotective effect for mouse kidney of breathing a gas mixture containing 8% O2 by morphometry of histological specimens.

Selective toxicity of buthionine sulfoximine (BSO) to melanoma cells in vitro and in vivo.

Purpose: Glutathione (GSH) was found to occur in relatively high concentrations in melanoma cells. The purpose of this study was to test the possible cytotoxic effects of an artificial decrease of the elevated GSH level.

Methods And Materials: The tests were made in vitro and in vivo.

[The effect of the gas hypoxic mixture GHM-8 on the capacity of the stromal clonogenic cells (CFU-F) in rat bone marrow for postradiation recovery].

The effect of gas hypoxic mixture, containing 8% of O2 (GHM-8), on the ability of cell precursors of haemopoietic stroma (which form colonies (clones) of fibroblasts (CFU-F) in a culture, and are present in the bone marrow of adult rats) to repair potentially lethal and sublethal radiation damages has been investigated. The recovery of CFU-F from potentially lethal damages, that was studied after their delayed survival in a culture following irradiation of animals, proceeds at nearly the same rate in cells irradiated both in the air and in hypoxic conditions (GHM-8). Fractionated irradiation reduces the radioprotective effect of GHM-8 for CFU-F, particularly for the radioresistant subpopulation; the ability of CFU-F to recover from sublethal radiation damages decreases.

[The capacity of rat clonogenic precursor cells of the hemopoietic stroma (CFU-F) to recover from radiation damages].

The ability of cell precursors of the haemopoietic stroma (CFU-F), that are present in the bone marrow of adult rats, to recover from potentially lethal and sublethal radiation damages has been investigated. The highest reparability, with respect to potentially lethal damages, is displayed by the most radioresistant CFU-F population, that forms loose colonies (clones) in a culture; the slope of the dose-response curve, not the extrapolation number, changes, and heterogeneity of the CFU-F population is observed. The results obtained confirm the presence of heterogeneity in the population of CFU-F, that was revealed in studying their radiosensitivity by the formation of dense and loose fibroblast colonies in a culture.

[The effect of intracellular pH on radiation damage to mammalian cells].

In experiments with Chinese hamster cells and Ehrlich ascites tumor cells it has been shown that a decrease in intracellular pH from 7.0 to 6.0, produced by 0.

[Histochemical and biochemical study of radiation injury of the kidneys in gas hypoxia].

A radioprotective effect of hypoxia was studied in kidney radiation. The use of hypoxic respiratory mixture containing 8% oxygen (the normal content is 21%) enhances kidney resistance to local single and fractionated irradiation. Determination of renal activity of succinate dehydrogenase, lactate dehydrogenase, acid and alkaline phosphatase and urinary N-acetyl-beta-D-glucosaminidase, gamma-glutamyl transferase, alkaline phosphatase, lactate dehydrogenase is recommended as tests for kidney radiation damage.

[The radioprotective effect of hypoxia on clonogenic cells of rat bone marrow stroma (KOE-F)].

A comparative study was made on the survival rate of cell-precursors of haemopoietic stroma, that form, in a rat bone marrow culture, colonies (clones) of fibroblasts (CFU-F) after gamma-irradiation of animals in the air or in a gas hypoxic mixture, containing 8% of O2 (GHM-8). Irradiation in GHM-8 was shown to increase the survival rate of CFU-F by 1.7 times (as compared to exposure in the air) as estimated by the total number of colonies that are formed in a culture; the radioprotective effect of GHM-8 was more pronounced for CFU-F which form dense colonies: DMF for dense and loose clones was 2.

[Morphofunctional characteristics of murine kidneys in single and fractionated irradiation in air and hypoxia (8% of O2)].

The protective effect of hypoxic gas mixture containing 8% of oxygen (HGM-8) has been studied in long terms after local single and fractional X-ray irradiation of the kidney in mice. Some criteria of injury shown that hypoxia protects the kidneys against irradiation, changes in irradiation dose constituting 1.25-1.

[Radioprotective action of gas hypoxia (8%) in local irradiation of the kidneys].

The radioprotective action of hypoxia in local irradiation of kidneys was studied. The experiments were carried out on hybrid mice (CBA x C57Bl) exposed to local X-ray irradiation through a lead diaphragm matched to the kidneys. In the experimental group the animals breathed in gaseous mixture with 8% of oxygen prior to and during irradiation.

[Use of respiratory mixture containing 8.0-8.5% of oxygen in hypoxic radiotherapy of cervical neoplasms].

Combined radiotherapy of patients with cervical carcinoma of stages IIb and IIIb was conducted. Hypoxia (8.0-8.

[The radioprotective effect of a hypoxic respiratory mixture (8% O2) for intestinal epithelial stem cells during single and fractionated irradiation of mice].

The method of intestinal "microcolonies" was used to study the radioprotective effect of a gas mixture, containing 8% of O2, on mice subjected to single and fractionated (5 fractions for 30 min) irradiation. The protective effect was indicated by a decreased slope of dose curves of the stem cell injury; the extrapolation number decreased simultaneously. So the values of dose modifying factors (DMF) were higher, when calculated by D0 ratio (where they amounted to 1.

[Radiation-protective action of a gas mixture containing 8% of oxygen in single and fractionated local irradiation of the kidneys].

The protective action of a hypoxic gaseous mixture, containing 8% of oxygen was studied in a long term after local single and fractionated irradiation. A degree of protection of all morphofunctional structures of the kidney, evaluated by different criteria, was approximately the same (1.25-1.

[The absorbed dosage and its fractionation in the radiation treatment of tumors in children].

Radiation therapy is widely used in pediatric oncology. Its use emphasizes the problems of the protection of growing tissues and organs. The paper is concerned with the problem of effective distribution of an ionizing radiation dose delivered to a locally advanced tumor in children.

[Effects of At-211 alpha irradiation on Ehrlich ascites tumor cells].

The biological effect of 211At alpha-particles has been investigated using the Chinese hamster fibroblasts and Ehrlich carcinoma cells growth in vitro. The mean energy of 211At alpha-particles is 6.8 MeV, LET in tissue is 70-160 keV/microns; the half-life period of decomposition of 211At is 7.

[Immediate results of hypoxiradiotherapy of malignant tumors].

The paper represents a comparative analysis of hypoxiradiotherapy of 202 patients with malignant tumors of different sites. A significant decrease (a 3.5-fold) in the number of severe local radiation reactions was noted in hypoxiradiotherapy of cancer of the esophagus, pancreas and metastases of seminoma to the retroperitoneal lymph nodes.

[Effect of short-term gaseous hypoxia (7.4-8.2% O2) on the body of normal subjects and cancer patients].

A clinical investigation of the tolerance of a short-term (15-30 min) normobaric gaseous hypoxia caused by the inhalation of mixtures containing 7.4-8.2% O2 was conducted.

[Radiation protection of mice with hypoxic gas mixtures after administration of anti-hypoxic agents].

It is shown that such substances as gutimine, antizol and mexamine increases the resistance of animals to short-term breathing of gas mixtures containing 6 and 5% oxygen. Even if some of them decrease the degree of radioprotective effect of hypoxia, they afford the possibility to safe use of breathing mixtures with lower oxygen content than endured by intact animals, with the resulting increase in radioprotection. Thus the antihypoxic substances can be tested during hypoxiradiotherapy of human tumors.

[Evaluation of the radioprotective effect of total gaseous hypoxia based on the criteria of delayed radiation damage].

Breathing with gas mixture containing 6-8% of oxygen during whole-body and large-field irradiation of mice diminishes the radiation-induced life-span shortening (DMF = 2.2) and decreases the degree of canescence (DMF = 1.5), the frequency and severity of nephro- and cardiosclerosis (DMF = 1.