Chemical Radioprotection and Radiosensitization of Mammalian Cells Growing in Vitro

Cytotoxicity of Ro-07-0582; enhancement by hyperthermia and protection by cysteamine

“…Cysteamine is a well known radical scavenger which protects against radiation damage in the presence of 02. Its protective effects against Ro-07-0582, and also against other electron-affinic drugs (Chapman et al, 1973) is primarily due to its ability to increase the pool of radical reducing species within cells, resulting in enhanced repair of freeradical damage in the targets. Both Ro-07-0582 and 02 may alter this target damage, resulting in cell death.…”

Effects of Amifostine on Radiation-induced Cardiac Damage

“…No radioprotection was seen in fully hypoxic conditions, maximum protection occurred in air or 50% oxygen and there was a reduction in protection for irradiations in 100% oxygen. Thiol compounds influence radiosensitivity, at least partly, by redox competition with oxygen for fixation or repair of damage (41,42). At very low oxygen concentrations the tissue is already protected by hypoxia and cannot be further protected by amifostine, in 100% oxygen the balance between fixation and repair is strongly in favor of fixation, making it more difficult to alter tissue radiosensitivity by the addition of thiols.…”

Interaction of radiosensitizers and WR-2721. I. Modification of skin radioprotection

“…These data indicate a competitive interaction between both sensitizers (02 and MISO) and WR-2721. This has previously been demonstrated in vitro with various sulphydryl compounds and electron-affinic radiosensitizers, for mammalian cells, for bacteria and for chemicals in solution (Dewey, 1963;Redpath & Willson, 1973;Chapman et al, 1973;Asquith et al, 1974;Hall et al, 1977;Cullen et al, 1980, Michael & Harrop, 1980Koch & Howell, 1980, 1981. The predominance of sensitization or protection has been shown to depend on the relative concentrations of the compounds and on the 02 status.…”