Radioadaptive response by low or high LET-radiation
Abstract
In space astronauts were constantly exposed to different radiations including high LET-radiations at low dose and low dose-rate It is a question whether there is different effectiveness among individual person exposed at different doses In this study to clarify the LET-dependency in radioadaptive response we applied human cultured cells and CB17 Icr mice They were irradiated with X-rays 3 Gy after pre-irradiation with X-rays or 200 KeV um Iron-beams at low doses 0-0 6 Gy and low dose rate 1mGy min Apoptosis incidence of them was measured by Hoechst33342 or HE staining In the case of low LET-radiation we previously reported that pre-irradiation of gamma-ray at a low dose or a low dose-rate before challenge X-ray-irradiation depressed the levels of p53 accumulation and apoptosis incidence in human cultured cells and mouse spleen However we here did not found the depression of apoptosis in the mouse exposed to pre-irradiation of Iron-beams 0 45 Gy These results indicated that there is no radioadaptive response in the cells for high LET-radiations From these findings it is suggested that high LET-radiations might induce irreparable DNA damage In space environment we can not expect the adaptation response for the depression of biological effects of space radiations containing high LET-radiations Therefore we like to conclude that astronauts should apply many kinds of radiation protection
- Publication:
-
36th COSPAR Scientific Assembly
- Pub Date:
- 2006
- Bibcode:
- 2006cosp...36..509T