title: DNA Double-strand Breaks Induced byFractionated Neutron Beam Irradiation for Boron Neutron Capture Therapy.
abstract: To use the 53BP1 foci assay to detect DNA double-strand breaks induced by fractionated neutron beam irradiation of normal cells.
  
  
  
  The Kyoto University Research Reactor heavy-water facility and gamma-ray irradiation system were used as experimental radiation sources. After fixation of Chinese Hamster Ovary cells with 3.6% formalin, immunofluorescence staining was performed. Number and size of foci were analyzed using ImageJ software.
  
  
  
  Fractionated neutron irradiation induced 25% fewer 53BP1 foci than single irradiation at the same dose. By contrast, gamma irradiation induced 30% fewer 53BP1 foci than single irradiation at the same dose. Fractionated neutron irradiation induced larger foci than gamma irradiation, raising the possibility that persistent unrepaired DNA damage was amplified due to the high linear energy transfer component in the neutron beam.
  
  
  
  Unrepaired cluster DNA damage was more prevalent after fractionated neutron irradiation than after gamma irradiation.
authors.affiliation: Research Reactor Institute, Kyoto University, Kumatori, Japan kinashi@rri.kyoto-u.ac.jp.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kinashi
authors.affiliation: Research Reactor Institute, Kyoto University, Kumatori, Japan.
authors.forename: Natsuya
authors.initials: N
authors.lastname: Yokomizo
authors.affiliation: Research Reactor Institute, Kyoto University, Kumatori, Japan.
authors.forename: Sentaro
authors.initials: S
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D016754:Boron Neutron Capture Therapy; D016466:CHO Cells; D002470:Cell Survival / Q000528:radiation effects; D006224:Cricetinae; D003412:Cricetulus; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D004260:DNA Repair / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays / Q000009:adverse effects; D009502:Neutrons / Q000009:adverse effects*; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D000071857:Tumor Suppressor p53-Binding Protein 1
keywords: Boron neutron capture therapy; DNA-DSBs; fractionation; neutron