title: Distribution of hydrogen peroxide-dependent reaction in a gelatin sample irradiated by carbon ion beam.
abstract: We investigated the amount and distribution of hydrogen peroxide (H(2)O(2)) generated in a solid gelatin sample irradiated by heavy ion (carbon) beam. We irradiated the gelatin sample, which contained a nitroxyl radical (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, TEMPOL), with a 290-MeV/nucleon carbon beam (~128 Gy). To verify the distribution of H(2)O(2) generation in the irradiated sample, we employed both electron paramagnetic resonance (EPR) spectroscopic and magnetic resonance (MR) imaging methods based on H(2)O(2)-dependent paramagnetic loss of TEMPOL. We obtained a distribution profile of the H(2)O(2)-dependent reaction in the gelatin sample when we irradiated gelatin samples with carbon beams with several different linear energy transfer (LET) values. Because the profiles of oxygen consumption in the gelatin sample measured by L-band EPR oxymetry and of the H(2)O(2)-dependent reaction have almost the same shape, the profile of the H(2)O(2)-dependent reaction can be used as an estimation of the profile of the generation of H(2)O(2). The H(2)O(2) profile in one intact gelatin sample scanned by 7-tesla MR imaging showed a similar shape as a result of the EPR experiment. We obtained several hundreds of micromolars of H(2)O(2) generated in a gelatin sample irradiated by carbon beam when 200 Gy was given at the surface of the sample. H(2)O(2) distribution was almost flat, with only a slight peak just before the end of the beam.
authors.affiliation: Radiation Modifier Research Team, Heavy-ion Radiobiology Research Group, Research Center for Charged Particle Therapy, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba-shi, Chiba, Japan. matsumok@nirs.go.jp
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Ichio
authors.initials: I
authors.lastname: Aoki
authors.forename: Ikuo
authors.initials: I
authors.lastname: Nakanishi
authors.forename: Atsuko
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Minako
authors.initials: M
authors.lastname: Nyui
authors.forename: Kazutoyo
authors.initials: K
authors.lastname: Endo
authors.forename: Kazunori
authors.initials: K
authors.lastname: Anzai
mesh_terms: D002244:Carbon; D003497:Cyclic N-Oxides / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004578:Electron Spin Resonance Spectroscopy; D005780:Gelatin / Q000378:metabolism / Q000528:radiation effects*; D020450:Heavy Ions; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000528:radiation effects*; D018499:Linear Energy Transfer; D010101:Oxygen Consumption / Q000528:radiation effects*; D011829:Radiation Dosage; D012996:Solutions; D013113:Spin Labels
chemical_list: D003497:Cyclic N-Oxides; D012996:Solutions; D013113:Spin Labels; D002244:Carbon; D005780:Gelatin; D006861:Hydrogen Peroxide; C001803:tempol