OH Radicals in Radiation Sensitization

Solute Radical Inactivation of the Sulfhydryl Enzyme Papain – Sensitization and Protection

“…In this connection it is interesting to note that some non-sulfhydryl sensitizers may also exhibit protective effects at higher concentrations (see ref. 19 and references cited therein).…”

Differential Modification of Oxic and Anoxic Components of Radiation Damage byT-butanol, an ·OH Radical Scavenger

“…Firstly, it should be pointed out that t-butanol exerts no protective effect under fully oxygenated conditions, whereas in barley seeds radioprotection is observed, even under conditions where the oxygen effect is maximally developed . Secondly, in bacterial spores t-butanol has been shown to desensitize the radiosensitizing action of certain additives, such as NO 3 - ( Powers et al 1972) and Ag+ (Richmond and Powers 1974), which are present during anoxic irradiation, or else enhance the anoxic radiation damage in the presence of certain other compounds, such as cobalt hexamine (Richmond, Simic and Powers 1975) and cis-dichlorodiamineplatinum II (Richmond and Powers 1976) . In one experiment, radiosensitization of anoxic damage in bacterial spores has also been reported (Ewing 1975), but the concentration of t-butanol used was very high (1 M) .…”

“…In bacterial spores irradiated in aqueous suspension, radiation-induced 'OH radicals mediate not only the anoxic sensitization by a variety of chemicals (Powers and Cross 1970, Powers, Richmond and Simic 1972, Powers and GampelJobbagy 1972, Richmond and Powers 1974, Ewing 1975, but also one part of the oxic damage observed at low (' 10-5 M) oxygen concentration Powers 1976, Ewing 1978) . Under anoxic conditions (with no sensitizer present), the involvement of the 'OH component of damage is not always readily demonstrable by the 'OH scavenging action of t-butanol (Cross, Simic and Powers 1973, Ewing 1975, but the protective effect of 0 .…”

Breaking Survival Curves and Oxygen Removal Times in Irradiated Bacterial Spores

“…The `times to anoxia' obtained with the two types of experiments can be brought into good agreement if t-butanol is present during irradiation . In water, with no other additive present, t-butanol does not reduce the spores' response in either air or 100 percent N 2 (Powers, Richmond, andSimic 1972, Ewing 1975) . However, over a range of low [0 2 1, the addition of t-butanol will reduce the effectiveness of the irradiation (Ewing and Powers 1976) .…”