Influence of PMMA shielding on DNA fragmentation induced in human fibroblasts by iron and titanium ions

TitoloInfluence of PMMA shielding on DNA fragmentation induced in human fibroblasts by iron and titanium ions
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione2005
AutoriDini, V., Antonelli Francesca, Belli M., Campa A., Esposito G., Simone G., Sorrentino E., and Tabocchini M.A.
RivistaRadiation Research
Parole chiaveCells, conference paper, controlled study, cosmic radiation, Cultured, DNA damage, DNA determination, DNA fragment, DNA fragmentation, DNA strand breakage, double stranded DNA, fibroblast, Fibroblasts, Heavy Ions, human, human cell, Humans, Iron, linear energy transfer, NASA Discipline Radiation Health, Non-NASA Center, nucleon, poly(methyl methacrylate), Polymethyl Methacrylate, priority journal, pulsed field gel electrophoresis, radiation dose, radiation protection, radiation shield, Titanium

In the framework of a collaborative project on the influence of the shielding on the biological effectiveness of space radiation, we studied DNA fragmentation induced by 1 GeV/nucleon iron ions and titanium ions with and without a 197-mm-thick polymethylmethacrylate (PMMA) shield in AG1522 human fibroblasts. Pulsed- and constant-field gel electrophoresis were used to analyze DNA fragmentation in the size range 1-5700 kbp. The results show that, mainly owing to a higher production of small fragments (1-23 kbp), titanium ions are more effective than iron ions at inducing DNA double-strand breaks (DSBs), their RBE being 2.4 and 1.5, respectively. The insertion of a PMMA shield decreases DNA breakage, with shielding protection factors (ratio of the unshielded/shielded cross sections for DSB production) of about 1.6 for iron ions and 2.1 for titanium ions. However, the DSB yield (no. of DSBs per unit mass per unit dose) is almost unaffected by the presence of the shield, and the relative contributions of the fragments in the different size ranges are almost the same with or without shielding. This indicates that, under our conditions, the effect of shielding is mainly to reduce the dose per unit incident fluence, leaving radiation quality practically unaffected. © 2005 by Radiation Research Society.


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