title: The difference in LET and ion species dependence for induction of initially measured and non-rejoined chromatin breaks in normal human fibroblasts.
abstract: We studied the LET and ion species dependence of the induction of chromatin breaks measured immediately after irradiation as initially measured breaks and after 24 h postirradiation incubation (37 degrees C) as non-rejoined breaks in normal human fibroblasts with different heavy ions, such as carbon, neon, silicon and iron, generated by the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Science (NIRS). Chromatin breaks were measured as an excess number of fragments of prematurely condensed chromosomes using premature chromosome condensation (PCC). The results showed that the number of excess fragments per cell per Gy for initially measured chromatin breaks was dependent on LET in the range from 13.3 to 113.1 keV/mum but was not dependent on ion species. On the other hand, the number of non-rejoined chromatin breaks detected after 24 h postirradiation incubation was clearly dependent on both LET and ion species. No significant difference was observed in the cross section for initially measured breaks, but a statistically significant difference was observed in the cross section for non-rejoined breaks among carbon, neon, silicon and iron ions. This suggests that the LET-dependent structure in the biological effects is reflected in biological consequences of repair processes.
authors.affiliation: Heavy-ion Radiobiology Research Group, National Institute of Radiological Sciences, 4-9-1 Anagawa, Chiba, Japan.
authors.forename: Chizuru
authors.initials: C
authors.lastname: Tsuruoka
authors.forename: Masao
authors.initials: M
authors.lastname: Suzuki
authors.forename: M Prakash
authors.initials: MP
authors.lastname: Hande
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Furusawa
authors.forename: Kazunori
authors.initials: K
authors.lastname: Anzai
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Okayasu
mesh_terms: D002460:Cell Line; D002843:Chromatin / Q000235:genetics* / Q000528:radiation effects*; D053960:DNA Breaks; D004260:DNA Repair / Q000235:genetics* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000502:physiology / Q000528:radiation effects*; D020450:Heavy Ions; D006801:Humans; D018499:Linear Energy Transfer / Q000502:physiology* / Q000528:radiation effects; D011829:Radiation Dosage
chemical_list: D002843:Chromatin