Effects of Small and Large First X-Ray Doses on the Two-Dose Recovery Pattern in HeLa S-3 Cells in Vitro

BERRY, ROGER J. Effects of Small and Large First X-Ray Doses on theTwo-Dose Recovery Pattern in HeLa S-3 Cells in Vitro. Radiation Res. 32, pp. 13-20 (1967). The shape of the two-dose recovery curve for cells of a HeLa S-3 subline is dependent on the size of the first X-ray dose. After large first doses (800 to 1000 rads), the trough in the curve is absent when intervals of up to 10 hours elapse between X-ray doses. This appears to be due to an increase in the radioresistance of the cell population, shown by a shallower dose-response curve for survivors of a first X-ray dose of 800 rads which are challenged 6 hours later with second doses of 100 to 600 rads. Differences in the patterns of recovery in HeLa cells and those reported for Chinese hamster cells are ascribed to differences in the degree of