Radiation factors and their influence on induction of oxygen resistance.
Shortly after gamma irradiation, flour beetles exhibited a decline in resistance to oxygen toxicity. Then, about 2 weeks after irradiation, the 50% lethal dose (LD50) exposure time in pure oxygen was much greater than that of nonirradiated beetles, and this enhanced resistance persisted for about 6 months. The magnitude of the enhancement was a function of dose, decreased with increasing age at irradiation, and was modified by radiation factors. Both dose protraction and dose fractionation reduced the development of oxygen resistance to approximately the same degree that it reduced acute radiation lethality. This suggests that both the initial sensitization and the later enhancement of resistance are correlated with the residual biological damage rather than with the physical dose or initial damage.
Lee
Y J
YJ
Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan 48072.
Ducoff
H S
HS
D000818:Animals; D002588:Cesium Radioisotopes; D004351:Drug Resistance / Q000528:radiation effects; D005260:Female; D005720:Gamma Rays; D008297:Male; D010100:Oxygen / Q000633:toxicity*; D014231:Tribolium / Q000187:drug effects / Q000528:radiation effects*
D002588:Cesium Radioisotopes; D010100:Oxygen