Abstract
Yield of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in heavy-ion irradiated human HL-60 cells was measured over an LET range of 20 keV/μm to 440 keV/μm using carbon, neon, silicon and iron ions. The ion species dependence was also examined for carbon and neon ions at an LET of 80 keV/μm. After irradiation, DNA was extracted from the cells and digested into nucleosides. 8-OHdG was separated as a single peak on a chromatogram of ECD detector. 8-OHdG yield was decreased with increasing LET with a saturation tendency in the high LET region. The yield of 8-OHdG for neon ions were significantly higher than that for carbon ions at an LET of 80 keV/μm. This result could result from the larger low-LET penumbra area compared with the case of carbon ions. The LET dependence of the oxygen effect for 8-OHdG production was examined to evaluate reduced oxygen effect at the high LET region. The yield of 8-OHdG at the hypoxic condition had a tendency to be saturated above the LET value of about 100 keV/μm, in contrast with the decrease of the yield with increasing LET for the air-saturated condition. These results are compatible with the oxygen-in-the-track model to explain the absence of oxygen effect for high-LET radiations.
