DNA Damage and Repair in Rodent and Human Cells after Exposure to JANUS Fission Spectrum Neutrons: A Minor Fraction of Single-strand Breaks as Revealed by Alkaline Elution is Refractory to Repair

Peak, Meyrick J.; Peak, Jennifer G.; Carnes, Bruce A.; Liu, C.M. Chang; Hill, Colin K.

doi:10.1080/09553008914550811

Cited by 13 publications

(1 citation statement)

References 25 publications

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“…This topic was recently reviewed (Peak and Peak, 1989a), and the problems in identifying the reactive chemical species involved were discussed therein. Large oxygen-enhancement ratios for DNA damage and cytotoxicity of UV-A strongly implicate reactive oxygen species (such as the hydroxyl radical, singlet oxygen, superoxide anion, or H202 in UV-A effects (Peak et al, 1983(Peak et al, ,1985(Peak et al, , 1987Tyrrell and Pidoux, 1989). It has been speculated that H202 might be a cytotoxic agent produced within cells as a result of the absorption of UV-A (Eisenstark, 1987;Kramer and Ames, 1987 martano and Tuveson, 1985;Tyrrell, 1985).…”

Section: Introductionmentioning

confidence: 99%

DNA BREAKS CAUSED BY MONOCHROMATIC 365 nm ULTRAVIOLET‐A RADIATION OR HYDROGEN PEROXIDE and THEIR REPAIR IN HUMAN EPITHELIOID and XERODERMA PIGMENTOSUM CELLS

Peak

Pilas

Dudek

et al. 1991

Photochem & Photobiology

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The induction and repair of DNA single-strand breaks (SSB) assayed by alkaline filter elution was compared in human epithelioid P3 and xeroderma pigmentosum (XP) cells exposed to monochromatic 365-nm UV-A radiation and H2O2. Initial yields of SSB were measured with the cells held at 0.5 degrees C during exposure. The yield from exposure to 365-nm radiation was slightly greater in XP than in P3 cells, whereas H2O2 produced more than three times as many SSB in P3 compared with XP cells. o-Phenanthroline (50 mM) markedly inhibited the yields of SSB induced in XP cells by H2O2, but had no effect on those produced by 365-nm UV-A. These results are consistent with the fact that P3 cells, unlike XP cells, have undetectable levels of catalase. The measured production of trace amounts of H2O2 by the actual 365-nm UV-A exposures was not sufficient to account for the numbers of breaks that were observed. Single-strand breaks produced by both agents were completely repaired after 50 min in P3 cells, as were H2O2-induced SSB in XP cells. However, 25% of the 365-nm UV-A-induced SSB in XP cells remained refractory to repair after 60 min. The results show that SSB produced by these two agents are different and that 365 nm radiation produces most SSB in cells by mechanisms other than by production of H2O2.

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