title: Inhibition of repair of radiation-induced strand breaks by hyperthermia, and its relationship to cell survival after hyperthermia alone.
abstract: Ehrlich ascites cells growing in vitro have been used to investigate the influence of hyperthermia on the formation and repair of DNA strand breaks after X-irradiation. Different heat pretreatments were given immediately prior to a dose of 6 Gy of X-rays. When a temperature of 42 degrees C was used, up to 4 hours of pretreatment had only a slight inhibitory effect on the repair of DNA strand breaks induced by radiation. At a temperature of 43 degrees C progressively more inhibition was observed with longer treatment times. This was also the case for temperatures of 44 degrees C and 45 degrees C. When the treatment times at 43-45 degrees C were longer, strand breaks in DNA were induced by the hyperthermic treatment alone. Under these conditions almost no repair was found of strand breaks induced by a subsequent radiation dose. The data obtained strongly suggest a correlation between the effect of the hyperthermic treatment alone on cell survival and the kinetics of repair of strand breaks in DNA as induced by radiation.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor; D002470:Cell Survival; D002478:Cells, Cultured; D004260:DNA Repair; D004273:DNA, Neoplasm / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D006358:Hot Temperature; D051379:Mice; D013997:Time Factors
chemical_list: D004273:DNA, Neoplasm