Dose dependency of FISH-detected translocations in stable and unstable cells after ¹³⁷Cs γ irradiation of human lymphocytes in vitro

Abstract

Human peripheral lymphocytes were exposed to ¹³⁷Cs γ-rays (0–4.3 Gy) in order to check the impact of unstable cells on the dose-response curve for translocations. Chromosomes 2, 4 and 8 were FISH-painted. 17,720 first dividing cells were analysed. For the discrimination between stable and unstable cells the painted and the counter-stained chromosomes were analysed at doses of 1 Gy and higher. The cell distribution of translocations follows a Poisson distribution. The data were fitted to the linear-quadratic function, y = c + αD + βD². As expected, the α coefficients of the dose-response curves for translocations in stable cells or in total cells do not differ. However, at doses >1 Gy, the frequency of all translocations in stable cells seems to be lower than the frequency in total cells. For the establishment of calibration curves for past dose assessment purposes, only complete translocations should be scored, in order to estimate reliable doses.

RENEB biodosimetry intercomparison analyzing translocations by FISH

“…However, the persistence of translocations is influenced by some factors, i.e. the type of translocations scored (Duran et al 2009), if the exposure is whole body or partial (Guerrero-Carbajal et al 1998, Duran et al 2002, the initial dose (Duran et al 2002, Sevan'kaev et al 2005, the dose fractionation (Muller et al 2005, Xuncl a et al 2008, the completeness and complexity of the aberration (Hande and Natarajan 1998, Lindholm et al 1998, Xiao et al 1999, Pala et al 2001, Duran et al 2002, Gardner and Tucker 2002 and the co-occurrence of translocations and unstable aberrations in the same cells (Rodr ıguez et al 2004, Romm andStephan 2004). Nevertheless, the analysis of translocations has been useful in retrospective biodosimetry studies (Salassidis et al 1994, Finnon et al 1995, Darroudi and Natarajan 1996, Snigiryova et al 1997, Montoro et al 2005).…”

Iodine-131 Dose Dependent Gene Expression in Thyroid Cancers and Corresponding Normal Tissues Following the Chernobyl Accident

“…Using individual I-131 dose estimates, we evaluated dose in three categories, without assumptions about the dose-response shape and assuming a linear dose-response. Because different radiobiological mechanisms might occur with increasing radiation doses including cell killing and induction of persistent chromosomal rearrangements, which themselves are known to follow non-linear relationship [36] , [37] , a curvilinear relationship for differential gene expression is plausible. Consistent with this idea, at least some genes ( SLC19A1 , SLC43A3 , ZNF493 ) exhibited a suggestion of non-linearity in differential dose-response.…”

Construction and Validation of a Dose-Response Curve Using the Comet Assay to Determine Human Radiosensitivity to Ionizing Radiation

“…Thus, calibration curves for CA and MN, with reference to ionizing radiation exposures, have already been constructed (Lloyd 1998;Schroder and Heimers 2002;Natarajan and Kesavan 2005). Although such biomarkers are unstable and, consequently, only predictive of recent exposures, the use of fluorescence in situ hybridization (FISH) techniques permits one to detect stable aberrations determining the dose received through long periods (Romm and Stephan 2004). All these biomarkers were used both as measure of in vivo irradiation and to identify individual patterns of response to Mladinic et al 2010).…”