title: The radiobiological effectiveness of carbon-ion beams on growing neurons.
abstract: OBJECTIVE
  Recently carbon-ion beams have been reported to be remarkably effective for controlling various cancers with less toxicity and are thought to be a promising modality for cancer treatment. However, the biological effect of carbon-ion beams arising on normal neuron remains unknown. Therefore, this study was undertaken to investigate the effect of carbon-ion beams on neurons by using both morphological and functional assays.
  
  
  METHODS
  Dorsal root ganglia (DRG) and sympathetic ganglion chains (SYMP) were isolated from day-8 and day-16 chick embryos and cultured for 20 h. Cultured neurons were exposed to carbon-ion beams and X-rays. Morphological changes, apoptosis and cell viability were evaluated with the Growth Cone Collapse (GCC), Terminal deoxynucleotidyl Transferase (TdT)-mediated deoxyUridine TriPhosphate (dUTP) nick End Labeling [TUNEL] assay and 4-[3-(4-iodophenyl)- 2-(4-nitrophenyl)- 2H-5-tetrazolio]- 1,3-benzenedisulfonate [WST-1] assays, respectively.
  
  
  RESULTS
  Irradiation caused GCC and neurite destruction on a time- and irradiation dose-dependent manner. Changes in morphological characteristics were similar following either irradiation. Morphological and functional assays showed that day-8 neurons were more radiosensitive than day-16 neurons, whereas, radiosensitivity of DRG was comparable to that of SYMP. The dose-response fitting curve utilising both GCC and TUNEL labeling index showed higher relative biological effectiveness (RBE) values were associated with lower lethal dose (LD) values, while lower RBE was associated with higher LD values.
  
  
  CONCLUSIONS
  Exposure to high-linear energy transfer (LET) irradiation is up to 3.2 more efficient to induce GCC and apoptosis, in early developed neuronal cells, than low-LET irradiation. GCC is a reliable method to assess the radiobiological response of neurons.
authors.affiliation: Department of Radiation Oncology, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Wael S
authors.initials: WS
authors.lastname: Al-Jahdari
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Yukari
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamada
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Shirai
authors.forename: Shin-Ei
authors.initials: SE
authors.lastname: Noda
authors.forename: Tomoo
authors.initials: T
authors.lastname: Funayama
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sakashita
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Saito
authors.forename: Fumio
authors.initials: F
authors.lastname: Goto
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002244:Carbon; D002470:Cell Survival / Q000528:radiation effects; D002642:Chick Embryo; D004307:Dose-Response Relationship, Radiation; D020450:Heavy Ions; D018499:Linear Energy Transfer; D009474:Neurons / Q000528:radiation effects*; D011853:Radiobiology; D012062:Relative Biological Effectiveness
chemical_list: D002244:Carbon