title: The difference that linear energy transfer makes to precursors of DNA strand breaks.
abstract: Using agarose gel electrophoresis, we have measured the yields of DN A single- and double-strand breaks (SSBs and DSBs) for plasmid DNA irradiated in aerobic aqueous solution with either 137Cs gamma rays or 4He ions with a mean LET of 94 or 150 keV micron-1. The presence of dimethyl sulfoxide (DMSO) resulted in a decrease in the yields of both SSBs and DSBs, with a greater decrease being apparent for gamma irradiation than for 4He-ion irradiation. Irradiation by 4He ions in the presence of N-(2-thioethyl)- 1,3-diaminopropane (WR-1065) resulted in a decrease in the yield of SSBs and a slightly larger decrease in the yield of DSBs. Together with results obtained previously, these observations suggest a substantial contribution to the formation of SSBs and DSBs by 4He ions by species containing at least two radicals and more than two radicals, respectively.
authors.affiliation: Department of Radiology, University of California at San Diego, La Jolla, 92093-0610, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Milligan
authors.forename: J A
authors.initials: JA
authors.lastname: Aguilera
authors.forename: C C
authors.initials: CC
authors.lastname: Wu
authors.forename: J Y
authors.initials: JY
authors.lastname: Ng
authors.forename: J F
authors.initials: JF
authors.lastname: Ward
mesh_terms: D004249:DNA Damage / Q000528:radiation effects*; D004260:DNA Repair / Q000528:radiation effects*; D004278:DNA, Superhelical / Q000528:radiation effects; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D005720:Gamma Rays; D006371:Helium; D017665:Hydroxyl Radical; D007554:Isotopes; D018499:Linear Energy Transfer; D008624:Mercaptoethylamines / Q000494:pharmacology; D010957:Plasmids; D011837:Radiation-Protective Agents / Q000494:pharmacology
chemical_list: D004278:DNA, Superhelical; D007554:Isotopes; D008624:Mercaptoethylamines; D011837:Radiation-Protective Agents; C020174:N-(2-mercaptoethyl)-1,3-diaminopropane; D006371:Helium; D017665:Hydroxyl Radical; D004121:Dimethyl Sulfoxide