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# A Comparison of the Lethal Effects of Intracellular Radionuclides in Human and Rodent Cells

Peter K. LeMotte and John B. Little
Vol. 95, No. 2 (Aug., 1983), pp. 359-369
DOI: 10.2307/3576261
Stable URL: http://www.jstor.org/stable/3576261
Page Count: 11
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## Abstract

The relative sensitivities of a human diploid fibroblast strain (AG1522) and an established line of contact-inhibited mouse embryo fibroblasts (10T1/2) were compared after incorporation of [3 H]thymidine or $[{}^{125}{\rm I}]\text{iododeoxyuridine}$ into the cellular DNA and growth at 37°C. Whereas these cells show similar sensitivities to acute X irradiation, the D0 for clonal survival of the mouse fibroblasts was 5- to 10-fold higher than the D0 for the human fibroblasts for both 3 H and 125 I. A large difference in sensitivity between these two cell types was also seen after protracted irradiation from 3 H2 O at 37°C, but this difference was markedly reduced when cells were exposed to 3 H2 O at 0°C to simulate an "acute" irradiation. An established human tumor cell line was similarly hypersensitive to killing by 3 H2 O at 37°C as compared with early passage diploid hamster embryo cells. These results indicate that human cells are more radiosensitive than rodent cells when a radiation dose is protracted over several days rather than given as an "acute" exposure, and are consistent with the hypothesis that human cells are hypersensitive to low-dose-rate irradiation as compared with rodent cells.

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