Abstract
This work is about the setup of an in vitro system to report low-dose of X-rays as measured as cytogenetic damage. Q- and multicolor FISH (m-FISH), for telomere length and chromosome instability analysis, respectively, were compared to evaluate their sensitivity in the low-dose range in human primary fibroblasts. No telomere length modulation was observed up to 1 Gy in cycling fibroblasts, though reported for high doses, by that frustrating the purpose of using it as a low-exposure marker. To date the m-FISH is the best setup for the assessment of the chromosome structural damage: it allows stable and instable aberrations to be detected all over the karyotype. Stable ones such as balanced translocations, are not eliminated due to cell-cycle as unstable ones, so they are considered transmissible markers for retrospective dosimetry. The induction of chromosome damage showed a clear dependence on dose delivered; unstable aberrations were demonstrated after doses of 0.1 Gy, and stable aberrations after doses higher than 0.5 Gy. Summarizing, q-FISH is unfit to report low exposures while m-FISH provides better results: unstable aberrations are sensible short-term reporters, while stable ones long report exposures but with a higher induction threshold.
Highlights
The use of ionizing radiations (IR) in many fields of human activities has promoted the need to develop radiation protection
The induction of chromosome damage showed a clear dependence on dose delivered; unstable aberrations were demonstrated after doses of 0.1 Gy, and stable aberrations after doses higher than 0.5 Gy
The analysis of dicentrics in solid-stained chromosome preparations is very reliable for the evaluation of recent and acute radiation exposures, not for chronic or past exposures in that the yield of dicentric chromosomes decreases over the time after irradiation (Bauchinger, 1995)
Summary
The use of ionizing radiations (IR) in many fields of human activities has promoted the need to develop radiation protection. The dicentric chromosomes is the biomarker of choice for investigating recent IR exposure (Bauchinger et al, 1984; Natarajan, 2002). In this context, it has been demonstrated that the dicentric assay is able to assess health risks and guide medical treatment decisions in the event of large scale radiation accidents like Chernobyl (Piatkin et al, 1989) or Goiania (Ramalho and Nascimento, 1991). The analysis of dicentrics (unstable aberrations) in solid-stained chromosome preparations is very reliable for the evaluation of recent and acute radiation exposures, not for chronic or past exposures in that the yield of dicentric chromosomes decreases over the time after irradiation (Bauchinger, 1995). As the aberrations involving the painted chromosomes represent only a subset of the total aberrations, the higher is the number of stained chromosome pairs in the same metaphase, the higher is the supplied information
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