The response of Chinese hamster V79-379A cells exposed to negative Pi-mesons: Evidence that increased radioresistance is dependent on linear energy transfer
- British Columbia Cancer Research Centre, Vancouver (Canada)
- Univ. of British Columbia, Vancouver (Canada)
Chinese hamster V79-379A cells exhibit low-dose hypersensitivity to 250 kVp X rays followed by an increased radioresistant response over the dose range 0.5-1 Gy. This phenomenon is not seen with neutrons. It was therefore postulated the induction of radioresistance might develop as a response to a cellular event(s) which predominates after low- and not high-LET radiation. To test this hypothesis, we measured the survival response of V79-379A cells exposed to pions. Clonogenic survival was assessed for cells irradiated in the Bragg peak (35 keV/{mu}m) and plateau region (10-20 keV/{mu}m) of the beam, using an automated microscope (DMIPS cell analyzer). As expected, peak pions were found to be more effective per unit of dose at killing cells than plateau pions. The survival curve for cells irradiated in the plateau of the pion beam was found to incorporate a region of low-dose hypersensitivity and increased radioresistance, the effective D{sub 0} was dose-dependent, ranging from 3.5-5. This was not seen with peak pions, where the effective D{sub 0} was, on average, constant reflecting a single-exponential survival curve. Fitting the data with an induced repair model indicates that the phenomenon of increased radioresistance is almost certainly dependent on LET. 23 refs., 2 figs., 1 tab.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 56773
- Report Number(s):
- CONF-9305202-; ISSN 0033-7587; TRN: 95:012952
- Journal Information:
- Radiation Research, Vol. 138, Issue 1; Conference: Molecular, cellular, and genetic basis of radiosensitivity at low doses: a case of induced repair, Whistler (Canada), 9-13 May 1993; Other Information: PBD: Apr 1994
- Country of Publication:
- United States
- Language:
- English
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