Using in vitro mammalian cells (Chinese hamster V79 and CHO cells) irradiated with 260 KVp X rays, we will evaluate two hypotheses concerning the mechanisms of sensitization by oxygen (O2): Hypothesis (A): Oxygen sensitizes by reacting at cellular sites formed by reactions of hydroxyl radicals (OH), and Hypothesis (B): The superoxide anion radical (O2) plays a major role in cellular damage from ionizing radiation. To reach conclusions, we will observe how various treatments and chemical additives alter radiation sensitivity. (The steepness of a survival curve is taken as an index of radiation sensitivity.) A knowledge of the intracellular concentrations of added chemical agents is fundamental to this evaluation. These experiments are an essential step toward our long-range goal of selecting the most effective combination of sensitizers and/or protectors to use when the cells being treated are at different O2 concentrations. Such knowledge has immediate, obvious relevance to clinical oncology.
| Ewing, D; Walton, H L (1991) Do.OH scavenger secondary radicals protect by competing with oxygen for cellular target sites? Radiat Res 128:29-36 |
| Ewing, D; Walton, H L; Guilfoil, D S et al. (1991) The relationship between the anoxic sensitivity and the extent of sensitization by nitrous oxide. Int J Radiat Biol 59:717-27 |
| Ewing, D; Koval, T M; Walton, H L (1986) Radiation sensitization by oxygen of in vitro mammalian cells: is .O-2 involved? Radiat Res 106:356-65 |
