Sequential Exposures of Mammalian Cells to Low- and High-LET Radiations: I. Lethal Effects Following X-Ray and Neon-Ion Irradiation

Ngo, Frank Q.H.; Blakely, Eleanor A.; Tobias, Cornelius A.

doi:10.2307/3575541

Cited by 85 publications

(35 citation statements)

References 34 publications

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“…A synergistic effect on the killing of mammalian cells by the mixed irradiations between high and low l.e.t. has been reported by some investigators (Railton et al 1975, Ngo et al 1981, McNally et al 1984. The 14N(n,p) 14 C reaction might also produce a synergistic effect on the killing of the cells together with the other mixed radiations in the beam.…”

Section: Discussionmentioning

confidence: 85%

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Cell Inactivation and DNA Single- and Double-strand Breaks in Cultured Mammalian Cells Irradiated by a Thermal Neutron Beam

Maki

Saito

Kobayashi

et al. 1986

International Journal of Radiation Biology and Related Studies

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The effects on the cellular viability and induction and repair kinetics of DNA strand breaks in HeLa cells were examined after exposure to a thermal neutron beam and compared with those after gamma-irradiation. The thermal neutron survival curve had no initial shoulder. The relative biological effectiveness (r.b.e.) value of the neutron beam was determined to be 2.2 for cell killing (ratio of D0 values), 1.8 and 0.89 for single strand breakage (ssb) by alkaline sedimentation and alkaline elution respectively, and for double strand breakage (dsb) 2.6 by neutral elution. No difference was observed between thermal neutrons and gamma-rays in the repair kinetics of ssb and dsb. It is suggested that the effect induced by the intracellular nuclear reaction, 14N(n,p)14C is mainly responsible for the high r.b.e. values observed.

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Section: Discussionmentioning

confidence: 85%

“…RE indicates relative elution defined by (1) given in §2. radiations, and the interaction results in a reduction of each survival curve shoulder (Ngo et al 1981, McNally et al 1984. Such an interaction might occur between the nuclear reactions in the neutron beam and the contaminating y-rays.…”

Section: Discussionmentioning

confidence: 96%

Cell Inactivation and DNA Single- and Double-strand Breaks in Cultured Mammalian Cells Irradiated by a Thermal Neutron Beam

Maki

Saito

Kobayashi

et al. 1986

International Journal of Radiation Biology and Related Studies

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“…Previous observations (McNally et al . 1984, Ngo et al . 1981 were similar; however, in those studies, interactions between high-and low-LET radiations were not as pronounced as in our study .…”

Section: Discussionmentioning

confidence: 95%

The Combined Effects of α-particles and X-rays on Cell Killing and Micronuclei Induction in Lung Epithelial Cells

Brooks

Newton

Shyr

et al. 1990

International Journal of Radiation Biology

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Understanding how cellular damage produced by high-linear energy transfer (LET) radiation interacts with that produced by low-LET is important both in radiation therapy and in evaluating risk. To study such interactions, rat lung epithelial cells (LEC) were grown on Mylar films and exposed to both X-rays and alpha-particles, separately or simultaneously. Cell killing, and the numbers of binucleated cells and micronuclei, were measured as indicators of damage. X-rays and alpha-particles given separately caused dose-related increases in cell cycle time, with alpha-particles producing greater mitotic delay than X-rays. Damage from alpha-particles and X-rays given simultaneously did not interact to alter further the cell cycle. Cell survival data following exposure to X-rays and alpha-particles, combined or individually, were fitted by linear-quadratic models. Survival curves following exposure to alpha-particles only, or to 1.0 Gy alpha-particles plus graded X-ray doses, were adequately described using only the linear (alpha) term of a linear-quadratic model with alpha coefficients of 0.9 +/- 0.04 and 1.03 +/- 0.18 Gy-1, respectively. Survival following exposure to X-rays only or to 0.06 Gy alpha-particles combined with X-rays was best fitted using both alpha and beta terms of the linear-quadratic model (0.12 +/- 0.03)D + (0.007 +/- 0.002)D2 and (0.57 +/- 0.08)D + (0.3 +/- 0.02)D2, respectively. The numbers of micronuclei produced by exposure to alpha-particles or X-rays alone increased linearly with dose, with slopes of 0.48 +/- 0.07 and 0.19 +/- 0.05 micronuclei/binucleated cell per Gy for alpha and X-rays, respectively. Simultaneous exposure to graded levels of X-rays and a constant alpha dose of either 1.0 or 0.06 Gy increased micronuclei frequency, with a slope of 0.74 +/- 0.05 or 0.58 +/- 0.04 micronuclei/binucleated cell per Gy, respectively. These slopes are similar to that produced by alpha-particles alone. These studies demonstrated that both cell killing and the induction of micronuclei were increased by combined exposures compared with that predicted for separate exposures.

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“…This results in a decreased dose-rate effect as well as less repair observed between fractions in fractionated dose schedules. In fact, some experimental evidence suggests an "inverse doserate" effect (i.e., a larger effect at a given dose for a fractionated or low dose-rate schedule than for a single high dose-rate administration) for the end points of cell survival (Ngo et al, 1981), neoplastic cell transformation (Hill et al, 1984, Yang et al, 1986, tumorigenesis in hamsters (Little et al, 1985) and mice (Ullrich, 1984), reciprocal translocations in mouse spermatogonial stem cells (Grahn et al, 1986), and life shortening in mice (Thomson et al, 1982). An hypothesis that the inverse dose-rate effect is due to a large change in radiosensitivity through the cell cycle has been made (Rossi and Kellerer, 1986) and recently expanded upon (Brenner and Hall, 1990, also, Brenner and Hall , this volume).…”

Section: B Hieh-let Radiationmentioning

confidence: 99%

Dose–Time–Response Models for Radiation Carcinogenesis

Curtis

Thomas

1992

Advances in Radiation Biology

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Sequential Exposures of Mammalian Cells to Low- and High-LET Radiations: I. Lethal Effects Following X-Ray and Neon-Ion Irradiation

Cited by 85 publications

References 34 publications

Cell Inactivation and DNA Single- and Double-strand Breaks in Cultured Mammalian Cells Irradiated by a Thermal Neutron Beam

Cell Inactivation and DNA Single- and Double-strand Breaks in Cultured Mammalian Cells Irradiated by a Thermal Neutron Beam

The Combined Effects of α-particles and X-rays on Cell Killing and Micronuclei Induction in Lung Epithelial Cells

Dose–Time–Response Models for Radiation Carcinogenesis

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