The relative biological effectiveness of densely ionizing heavy-ion radiation for inducing ocular cataracts in wild type versus mice heterozygous for the ATM gene
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The accelerated appearance of ocular cataracts at younger ages has been recorded in both astronauts and airline pilots, and is usually attributed to high-energy heavy ions in galactic cosmic ray radiation. We have previously shown that high-LET 1-GeV/nucleon 56Fe ions are significantly more effective than X-rays in producing cataracts in mice. We have also shown that mice haploinsufficient for ATM develop cataracts earlier than wild-type animals, when exposed to either low-LET X-rays or high-LET 56Fe ions. In this paper we derive quantitative estimates for the relative biological effectiveness (RBE) of high energy 56Fe ions compared with X-rays, both for wild type and for mice haploinsufficient for ATM. There is a clear trend toward higher RBE’s in haploinsufficient animals, both for low- and high-grade cataracts. Haploinsufficiency for ATM results in an enhanced sensitivity to X-rays compared with the wild type, and this enhancement appears even larger after exposure to high-LET heavy ions.
KeywordsCataract Relative Biological Effectiveness Ataxia Telangiectasia Airline Pilot High Relative Biological Effectiveness
This research was supported by NASA Grant No. NAG 9-1519 and by the Office of Science (BER) US Department of Energy Grant No. DE-FG02-03ER63629.
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