title: DNA-lesion and cell death by alpha-particles and nitrogen ions.
abstract: When the natural logarithm of the surviving fraction is plotted against the dose of radiation, curves with shoulders at relatively high survival levels are obtained after gamma-rays. The curves were practically linear in case of HMV-I and HA-1 cells irradiated by charged particle beams. These cells were derived from human malignant melanoma and Chinese hamster cells, respectively. The amount of DNA single strand breaks (ssb) by gamma-rays or nitrogen-ions (LET=530KeV/micrometers) in HMV-I cells increases linearly with increment in dose, when the ssb is detected using the alkaline elution technique. There is no close relationship between the dose-response curve of the ssb and the dose-survival curves after gamma-rays or N-ions. The amount of DNA double strand breaks (dsb) by gamma-rays increases quadratically with increment of dose, in both HMV-I cells and HA-1 cells, when the dsb is detected using the neutral elution technique. The survival fraction for HA-1 cells is slightly higher than that for HMV-I cells, at the same dose, and the amount of dsb for HA-1 cells is considerably greater than that for HMV-I cells. These results suggest that the radiosensitivities to gamma-rays in different cell lines do not correspond to the number of DNA strand breaks. The amount of both non-repairable ssb and dsb also increases quadratically with increment of dose for gamma-rays and almost linearly with increment of dose for N-ions and alpha-particles (LET=36keV/micrometers for HA-1 cells and LET=77keV/micrometers for HMV-I cells). The dose-response curves for non-repairable dsb in case of these radiations seemed to mirror image the dose-survival curves for these radiations, in both cell lines. The number of non-repairable DNA strand breaks in the two cell lines, at the same level of survival was much the same. These results show the close relationship between the induction of non-repairable DNA strand breaks and cell killing.
authors.affiliation: Institute of Physical and Chemical Research, Wako-shi, Saitama, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Kaneko
authors.forename: K
authors.initials: K
authors.lastname: Eguchi-Kasai
authors.forename: T
authors.initials: T
authors.lastname: Kosaka
authors.forename: K
authors.initials: K
authors.lastname: Nakano
authors.forename: A
authors.initials: A
authors.lastname: Maruhashi
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D000512:Alpha Particles; D000818:Animals; D016923:Cell Death; D002460:Cell Line; D002470:Cell Survival; D006224:Cricetinae; D003412:Cricetulus; D017357:Cyclotrons; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006801:Humans; D018499:Linear Energy Transfer; D008545:Melanoma / Q000473:pathology; D009584:Nitrogen; D011829:Radiation Dosage; D014407:Tumor Cells, Cultured
chemical_list: D009584:Nitrogen