Combined effects of x irradiation and hyperthermia on CHO cells for various temperatures and orders of application

Journal Article · Wed Feb 01 04:00:00 EST 1978 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3574816· OSTI ID:7075822

Sapareto, S A; Hopwood, L E; Dewey, W C

The survival of CHO cells to hyperthermic treatment combined with radiation indicates that heat given either immediately before or immediately after irradiation radiosensitizers S-phase cells more than G1 cells, thus resulting in similar absolute levels of survival for each phase. No difference in effect was observed for different temperatures (42.0 to 45.5/sup 0/C) applied before irradiation in either G1 or S when times of heating were adjusted to obtain the same survival (0.5 to 0.6) from heat alone. When heat was administered after irradiation and the time between treatments was increased, repair during G1 of radiation damage which interacted with subsequent heat damage occurred over a 2-hr period. Survival increased from a synergistic level to an independent level with kinetics similar to those seen for repair between split x-ray doses. For this experiment, the heat treatments were administered at either 42.5 or 45.5/sup 0/C with times of heating adjusted to obtain the same survival (0.15) from heat alone. When cells were treated similarly in S phase using either 42.5 or 45.5/sup 0/C (survival from heat alone was 0.2), recovery from a synergistic level of survival was similar to that observed in G1; however, survival did not reach an independent level by 120 min between treatments. When relatively sublethal heat doses at either 42.5 or 45.5/sup 0/C were applied either before, during, or after irradiation, the maximum reduction in survival of asynchronous cells occurred when heat was present during and immediately following irradation, presumably due to heat increasing the fixation of radiation damage. A sixfold difference in survival was observed with about a 5-min change in the timing of radiation with respect to heating. This sensitivity of survival to changes in protocol may have considerable implications in the combined use of hyperthermia and radiation for cancer therapy.

• Research Organization: Colorado State Univ., Fort Collins
• OSTI ID: 7075822
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 73:2; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

560121* -- Radiation Effects on Cells-- External Source-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BODY TEMPERATURE
CELL CULTURES
ELECTROMAGNETIC RADIATION
HAMSTERS
HYPERTHERMIA
IONIZING RADIATIONS
IRRADIATION
MAMMALS
RADIATION EFFECTS
RADIATIONS
RADIOSENSITIVITY EFFECTS
RECOVERY
REPAIR
RODENTS
SURVIVAL TIME
TEMPERATURE EFFECTS
TIME DEPENDENCE
VERTEBRATES
X RADIATION