TY - JOUR
T1 - Dose - Response of initial G2-chromatid breaks induced in normal human fibroblasts by heavy ions
AU - Kawata, T.
AU - Durante, M.
AU - Furusawa, Y.
AU - George, K.
AU - Takai, N.
AU - Wu, H.
AU - Cucinotta, F. A.
N1 - Funding Information:
This work was supported by NASA Space Radiation Health Program. T. K. is supported by an NRC grant (fellowship no. 9818170).
PY - 2001
Y1 - 2001
N2 - Purpose: To investigate initial chromatid breaks in prematurely condensed G2 chromosomes following exposure to heavy ions of different LET. Material and methods: Exponentially growing human fibroblast cells AG 1522 were irradiated with γ-rays, energetic carbon (13 keV/μm, 80 keV/μm), silicon (55keV/μm) and iron (140 keV/μm, 185 keV/μm, 440 keV/μm) ions. Chromosomes were prematurely condensed using calyculin-A. Initial chromatid-type and isochromatid breaks in G2 cells were scored. Results: The dose-response curves for total chromatid breaks were linear regardless of radiation type. The relative biological effectiveness (RBE) showed a LET-dependent increase, peaking around 2.7 at 55-80 keV/μm and decreasing at higher LET. The dose - response curves for isochromatid-type breaks were linear for high-LET radiations, but linear-quadratic for γ-rays and 13 keV/μm carbon ions. The RBE for the induction of isochromatid breaks obtained from linear components increased rapidly between 13 keV/μm (about 7) and 80 keV/μm carbon (about 71), and decreased gradually until 440 keV/μm iron ions (about 66). Conclusions: High-LET radiations are more effective at inducing isochromatid breaks, while low-LET radiations are more effective at inducing chromatid-type breaks. The densely ionizing track structures of heavy ions and the proximity of sister chromatids in G2 cells result in an increase in isochromatid breaks.
AB - Purpose: To investigate initial chromatid breaks in prematurely condensed G2 chromosomes following exposure to heavy ions of different LET. Material and methods: Exponentially growing human fibroblast cells AG 1522 were irradiated with γ-rays, energetic carbon (13 keV/μm, 80 keV/μm), silicon (55keV/μm) and iron (140 keV/μm, 185 keV/μm, 440 keV/μm) ions. Chromosomes were prematurely condensed using calyculin-A. Initial chromatid-type and isochromatid breaks in G2 cells were scored. Results: The dose-response curves for total chromatid breaks were linear regardless of radiation type. The relative biological effectiveness (RBE) showed a LET-dependent increase, peaking around 2.7 at 55-80 keV/μm and decreasing at higher LET. The dose - response curves for isochromatid-type breaks were linear for high-LET radiations, but linear-quadratic for γ-rays and 13 keV/μm carbon ions. The RBE for the induction of isochromatid breaks obtained from linear components increased rapidly between 13 keV/μm (about 7) and 80 keV/μm carbon (about 71), and decreased gradually until 440 keV/μm iron ions (about 66). Conclusions: High-LET radiations are more effective at inducing isochromatid breaks, while low-LET radiations are more effective at inducing chromatid-type breaks. The densely ionizing track structures of heavy ions and the proximity of sister chromatids in G2 cells result in an increase in isochromatid breaks.
UR - http://www.scopus.com/inward/record.url?scp=0035136361&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035136361&partnerID=8YFLogxK
U2 - 10.1080/09553000010007686
DO - 10.1080/09553000010007686
M3 - Article
C2 - 11236923
AN - SCOPUS:0035136361
SN - 0955-3002
VL - 77
SP - 165
EP - 174
JO - International Journal of Radiation Biology
JF - International Journal of Radiation Biology
IS - 2
ER -