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Extrapolation of the dna fragment-size distribution after high-dose irradiation to predict effects at low dosesThe patterns of DSBs induced in the genome are different for sparsely and densely ionizing radiations: In the former case, the patterns are well described by a random-breakage model; in the latter, a more sophisticated tool is needed. We used a Monte Carlo algorithm with a random-walk geometry of chromatin, and a track structure defined by the radial distribution of energy deposition from an incident ion, to fit the PFGE data for fragment-size distribution after high-dose irradiation. These fits determined the unknown parameters of the model, enabling the extrapolation of data for high-dose irradiation to the low doses that are relevant for NASA space radiation research. The randomly-located-clusters formalism was used to speed the simulations. It was shown that only one adjustable parameter, Q, the track efficiency parameter, was necessary to predict DNA fragment sizes for wide ranges of doses. This parameter was determined for a variety of radiations and LETs and was used to predict the DSB patterns at the HPRT locus of the human X chromosome after low-dose irradiation. It was found that high-LET radiation would be more likely than low-LET radiation to induce additional DSBs within the HPRT gene if this gene already contained one DSB.
Document ID
20040088724
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Ponomarev, A. L.
(NASA Johnson Space Center Houston TX United States)
Cucinotta, F. A.
Sachs, R. K.
Brenner, D. J.
Peterson, L. E.
Date Acquired
August 21, 2013
Publication Date
November 1, 2001
Publication Information
Publication: Radiation research
Volume: 156
Issue: 5 Pt 2
ISSN: 0033-7587
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: ES-07361
CONTRACT_GRANT: RR-11623
CONTRACT_GRANT: CA-49062
CONTRACT_GRANT: CA-24232
CONTRACT_GRANT: CA-77285
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Radiation Health
NASA Center JSC

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