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International audience; Curcumin has shown a wide range of properties such as anti-inflammatory and anti-carcinogenic properties. Many of these effects, mainly the anti-carcinogenic effect, could be linked to its anti-oxidant effects. Nevertheless, some studies suggest that this natural compound possesses both pro- and anti-oxidative effects and that curcumin could be a genotoxic agent for some cell lines. We evaluated the genetic damage induced by curcumin to human lymphocytes exposed to increasing concentrations (0-50 μg/ml) of curcumin. Biomarkers such as chromosome aberrations (CAs) and sister chromatid exchange (SCE) were analyzed. In addition to the cytogenetic analysis, the effect of curcumin in the cell proliferation kinetics (CPK) by the proliferation index (PI) was also analyzed. The results indicated that high concentrations of curcumin induced CAs, mainly acentric fragments. SCEs rate was not statistically different from the control group in any curcumin treated cell group. The PI of cells treated with 2 and 5 μg/ml of curcumin were statistically significant from the control group and finally, the MI showed a tendency to increase in all the concentrations of curcumin tested. In conclusion, it can be assumed that the higher concentrations of curcumin evaluated have a cyto and genotoxic effect, in vitro, for human peripheral lymphocytes. © 2012 Elsevier Ltd.

International audience; Fundamentals of biological dosimetry are described in the International Atomic Energy Agency manual, but all over the world each laboratory is using its own protocol. To test the influence of protocol variations, some blood samples were exposed to 0.5 Gy of gamma radiation and mitotic index and dicentric rates were measured under different experimental conditions. The effect of seven parameters [bromodeoxyuridin (BrdU), phytohaemagglutinin and colcemid concentrations, blood and medium volumes, culture duration and incubation temperature] was tested using a Placket and Burman experimental design. The analysis reveals that the mitotic index was influenced by the concentration of BrdU, medium and blood volumes, the culture duration and the temperature. However, none of the factors has a significant impact on the yield of dicentrics. The dicentric assay is robust against reagent variations within the range tested. These results could be used by relevant laboratories as elements of their procedures robustness in any event requiring such demonstration. © The Author 2012. Published by Oxford University Press. All rights reserved.

The association between ionizing radiation and the subsequent development of osteosarcoma has been well described, but little is known about the cytogenetic and molecular events, which could be involved in the formation of radiation-induced osteosarcomas. Here, we performed comparative genomic hybridization (CGH) to detect chromosomal copy number changes in a series of 16 rat osteosarcomas induced by injection of plutonium-238. Recurrent gains/amplifications were observed at chromosomal regions 3p12-q12, 3q41-qter, 4q41-qter, 6q12-q16, 7q22-q34, 8q11-q23, 9q11-q22, 10q32.1-qter, and 12q, whereas recurrent losses were observed at 1p, 1q, 3q23-q35, 5q21-q33, 8q24-q31, 10q22-q25, 15p, 15q, and 18q. The gained region at 7q22-q34 was homologous to human chromosome bands 12q13-q15/8q24/22q11-q13, including the loci of Mdm2, Cdk4, c-Myc and Pdgf-b genes. The lost regions at 5q21-q33, 10q22-q25 and 15q contained tumor suppressor genes such as p16INK4a/p19ARF, Tp53 and Rb1. To identify potential target gene(s) for the chromosomal aberrations, we compared the expression levels of several candidate genes, located within the regions of frequent chromosomal aberrations, between the tumors and normal osteoblasts by using quantitative RT-PCR analysis. The Cdk4, c-Myc, Pdgf-b and p57KIP2 genes were thought to be possible target genes for the frequent chromosomal gain at 7q22-34 and loss at 1q in the tumors, respectively. In addition, mutations of the Tp53 gene were found in 27% (4 of 15) osteosarcomas. Our data may contribute to further understanding of the molecular mechanisms underlying osteosarcomas induced by ionizing radiation in human.

International audience; In accidental exposure to ionizing radiation, it is essential to estimate the dose received by the victims. Currently dicentric scoring is the best biological indicator of exposure. The standard biological dosimetry procedure (500 metaphases scored manually) is suitable for a few dose estimations, but the time needed for analysis can be problematic in the case of a large-scale accident. Recently, a new methodology using automatic detection of dicentrics has greatly decreased the time needed for dose estimation and preserves the accuracy of the estimation. However, the capability to detect nonhomogeneous partial-body exposures is an important advantage of dicentric scoring-based biodosimetry, and this remains to be tested with automatic scoring. Thus we analyzed the results obtained with in vitro blood dilutions and in real cases of accidental exposure (partial- or whole-body exposure) using manual scoring and automatic detection of dicentrics. We confirmed that automatic detection allows threefold quicker dicentric scoring than the manual procedure with similar dose estimations and uncertainty intervals. The results concerning partial-body exposures were particularly promising, and homogeneously exposed samples were correctly distinguished from heterogeneously exposed samples containing 5 to 75 of blood irradiated with 2 Gy. In addition, the results obtained for real accident cases were similar whatever the methodology used. This study demonstrates that automatic detection of dicentrics is a credible alternative for recent and acute cases of whole- and partial-body accidental exposures to ionizing radiation. © 2012 by Radiation Research Society.

cited By 16; The purpose of this study was to evaluate the in vivo dose-response relation of chromosome aberration formation and distribution in a context of localised and fractionated radiotherapy. Cytogenetic analysis was applied to eight patients, all treated for the same tumour localisation; the same localisation was used to prevent the variability usually observed between patients treated with radiotherapy and to allow the corresponding roles of the size of irradiation field and of the dose rate to be studied. The yield of dicentrics, centric rings and fragments was measured in blood samples taken before treatment, during the course of radiotherapy and up to 6 months after. After the first fraction of radiotherapy, we observed that the whole-body dose estimated from the yield of dicentrics and rings was higher (0.35±0.2 Gy) than the calculated equivalent whole-body dose (0.07±0.04 Gy). By contrast, the partial-body dose derived from the Qdr (quotient of dicentrics and rings) model was estimated to be 2.2±0.3 Gy, which agreed quite well with the dose delivered to the tumour (2.1±0.1 Gy). We also found a correlation between the yield of induced chromosome aberrations and the target field size (p=0.014). U-value analysis showed that the distribution of dicentrics and rings was overdispersed, despite the fractionation of the exposure, and a positive correlation between the U-value and the dose rate was observed (p=0.017). Overall, these results suggest that the proportion of undamaged lymphocytes could increase with the dose rate. © 2010 The British Institute of Radiology.

Following large-scale accidental overexposure to ionising radiation, a rapid triage of the exposed population can be performed by scoring dicentrics and ring chromosomes in 50 metaphases. This is rapid but not accurate. Following this triage step, the dose can be estimated by scoring 500 metaphases. This is lengthy but very accurate. To improve the methodology, we propose using software for automatic dicentric scoring, which was tested on 63 victims of a radiological accident. The method using automatic dicentric scoring was compared with the standard methods of manual scoring. The comparison of the doses obtained shows that the automatic method could replace the two steps of the manual scoring (50 and 500 metaphases). In fact, the automatic scoring method is more accurate than the manual scoring of 50 metaphases and can therefore be used for triage. © EDP Sciences, 2010.; En cas d’accident radiologique impactant un grand nombre d’individus, il est primordial de différencier rapidement les individus exposés des individus non exposés. Le laboratoire de dosimétrie biologique de l’IRSN développe des méthodes pour répondre à ce type de situation. La méthode de référence est basée sur une estimation rapide de la dose après comptage des dicentriques et des anneaux dans 50 métaphases. À l’issue de cette étape de tri de la population exposée, une estimation plus précise de la dose reçue peut être nécessaire. Cette étape est longue car elle nécessite l’observation des aberrations chromosomiques dans au moins 500 métaphases. Pour améliorer cette méthodologie en deux étapes, nous avons étudié l’utilisation d’un logiciel de détection automatique des dicentriques dans un cas réel d’accident radiologique impliquant 63 victimes. Cette méthode a été comparée aux méthodes manuelles de références. La comparaison des doses obtenues montre que la méthode automatique peut remplacer les deux étapes du comptage manuel (50 et 500 métaphases), car elle cumule les avantages de chacune d’elles : rapidité et précision.

In the first part of this review, we examined through an extensive literature review, the influence of various factors related to the individual (age, sex, alcohol and tobacco) on the rate of translocation. In the second part, our literature review focused on the study of more toxic factors related to occupational exposure. All toxic agents tested induced an increase in the translocation rate in lymphocytes of exposed people. However 2 agents (polycyclic aromatic hydrocarbons -PAHs- and heavy metals) increase significantly the rate of translocation of exposed persons. This increase is function to the dose and duration of exposure. The sensitivity of FISH technique has highlighted the necessity of protective equipment. For all the toxic factors related to occupational exposure, protective equipment or exposure conditions reduced significantly the translocations rate of exposed subjects. Thus the FISH technique could be an exposure warning indicator. In conclusion, it is important to know as well the personnel and occupational curriculum of an individual if a retrospective dose assessment is required. Thus, the rate of translocations threshold will be based on the lifestyle rate. © EDP Sciences, 2010.; Dans la première partie de cette revue, nous avons examiné, au travers d’une étude bibliographique approfondie, l’influence de différents facteurs liés à l’individu (âge, sexe, consommation d’alcool ou de tabac) sur le taux de translocations. Dans cette seconde partie, notre revue de la littérature s’est attachée à l’étude de facteurs plus toxiques liés à une exposition professionnelle. Tous les agents toxiques analysés induisent une augmentation du taux de translocations au sein des lymphocytes des personnes exposées. Cependant 2 agents (hydrocarbures aromatiques polycycliques –HAPs- et les métaux lourds) augmentent de manière significative le taux des translocations des personnes exposées. Ce type d’agents toxiques augmente le taux de translocations proportionnellement à la dose et à la durée d’exposition. La sensibilité de la technique FISH a permis de mettre en évidence la nécessité et le bon fonctionnement des équipements de protection. Pour tous les facteurs toxiques liés à une exposition professionnelle, un équipement de protection adapté et ergonomique ou bien la période d’exposition ont réduit significativement le taux de translocations des individus exposés. Ainsi la technique FISH pourrait servir d’indicateur d’exposition. En conclusion, afin d’évaluer rétrospectivement l’exposition d’un individu, il est important de connaitre le plus précisément possible son curriculum clastogène et son âge. Ainsi, un taux de translocations limite pourrait être établi en fonction de l’impact des expositions professionnelles et environnementales connues aujourd’hui et de la connaissance du passé de l’individu.

The assessment of exposure to ionizing radiation, carried out long time after exposure, is currently performed by scoring of translocations, a specific type of chromosomal aberrations. The translocations rate observed in peripheral blood lymphocytes of exposed subjects is compared to that observed in a control population. However, the translocation specificity towards radiation exposure is not clearly identified. To avoid any hasty conclusion, it is necessary to identify all the factors likely to induce translocation. To our knowledge, no study has thus far examined the effects of all these different factors on translocation rates. A review of the literature thus allowed us to assess the impact of host factors and lifestyle on the production of translocations. This study confirms that age appears to be the factor having the greatest impact on the rate of translocations, especially over 60 years. To date, the factor "age" is already considered in estimating the impact of radiation on the rate of translocation for all age groups. However, the study also shows that this rate varies significantly when the patient is exposed simultaneously and significantly towards many lifestyle agents. A precise threshold translocation rate should thus be established as a function of known behavioral exposures, below which it is impossible to conclude that radiological exposure has occurred. The effects of chemicals on the translocation rate after occupational exposure will be the subject of a second part. © EDP Sciences, 2010.; L’évaluation de l’exposition aux rayonnements ionisants, effectuée longtemps après l’exposition, est actuellement réalisée en dénombrant les aberrations chromosomiques de type translocations. Le taux de ces translocations observées dans les lymphocytes des personnes exposées est comparé au taux observé au sein d’une population contrôle. Toutefois, la spécificité des translocations vis-à-vis de l’irradiation n’est pas clairement identifiée. Afin d’éviter toute conclusion hâtive, il est nécessaire d’identifier tous les facteurs susceptibles d’induire des translocations. À notre connaissance, aucune synthèse sur l’effet de ces différents facteurs sur le taux de translocations n’a été réalisée à ce jour. Cette recherche bibliographique a confirmé l’impact de certains facteurs personnels sur l’augmentation des translocations. Cette étude corrobore que l’âge s’avère être le facteur ayant le plus d’impact sur le taux de translocations, notamment après 60 ans. À ce jour, le facteur « âge » est déjà considéré dans l’estimation du taux de translocations après suspicion d’exposition aux rayonnements ionisants pour toutes les classes d’âge. L’étude montre également que ce taux varie significativement lorsque le patient est exposé simultanément et de manière importante et chronique à une combinaison alcool et tabac. Ainsi, une courbe du taux de translocations devrait être établie en fonction de la consommation excessive de ce type d’agent pour chaque individu. Ainsi il serait alors possible de déterminer le taux de translocations induit uniquement par une exposition radiologique. Les effets des agents toxiques sur le taux de translocations après exposition professionnelle feront l’objet d’une deuxième partie.

Purpose To compare translocation rate using either M-FISH or FISH-3 in two patients treated for head and neck cancer, with a view to retrospective dosimetry. Materials and methods Translocation analysis was performed on peripheral blood lymphocyte cultures from blood samples taken at different times during the radiotherapy (0 Gy, 12 Gy and 50 Gy) and a few months after the end of the treatment (follow-up). Results Estimated translocation yield varied according to the FISH technique used. At 50 Gy and follow-up points, the translocation yields were higher with FISH-3 than with M-FISH. This difference can be attributed to three events. First, an increase in complex aberrations was observed for 50 Gy and follow-up points compared with 0 Gy and 12 Gy points. Second, at the end of treatment for patient A, involvement of chromosomes 2, 4, 12 in translocations was less than expected according to the Lucas formula. Third, a clone bearing a translocation involving a FISH-3 painted chromosome was detected. Conclusions More translocations were detected with M-FISH than with FISH-3, and so M-FISH is expected to improve the accuracy of chromosome aberration analyses in some situations.

To compare me responses of the different lymphocyte sub-types after an exposure of whole blood to low doses of ionizing radiation, we examined variations in gene expression in different lymphocyte subpopulations using microarray technology. Blood samples from five healthy donors were independently exposed to 0 (sham irradiation), 0.05 and 0.5 Gy of ionizing radiation. Three and 24 h after exposure, CD56+, CD4+ and CD8+ cells were negatively isolated. RNA from each set of experimental conditions was competitively hybridized on 25k oligonucleotide microarrays. Modifications of gene expression were measured after both intervals and in all cell types. Twenty-four hours after exposure to 0.5 Gy, we observed an induction of the expression of BAX, PCNA, GADD45, DDB2 and CDKNIA. However, the numbers of modulated genes greatly differed between cell types. In particular, 3 h after exposure to doses as low as 0.05 Gy, the number of down-modulated genes was 10 times greater for CD4+ cells than for all other cell types. Moreover, most of these repressed genes were taking part in the cell processes of protein biosynthesis and oxidative phosphorylation. The results suggest that several biological pathways in CD4+ cells could be sensitive to low doses of radiation. Therefore, specifically studying CD4+ cells could help to understand the mechanisms involved in low-dose response and allow their detection.

Purpose: To compare the efficiency of different cytogenetic tools in estimating the doses received by four people involved in the Lilo accident and to monitor the dose estimate over 4.5 years. Materials and methods: Several young Georgian frontier guards handled at least one of the 12 Caesium sources found in a former Russian military camp. Overexposure lasted from July 1996 to May 1997. The Institute for Radiological Protection and Nuclear Safety (IRSN) obtained blood samples taken at several intervals post-exposure from the four most highly-exposed people. Dose estimation was performed using dicentric and translocation scoring. Results: The first dose estimations performed by dicentric scoring gave whole-body doses ranging from 0.4 to 1.3 Gy. Overexposure was complex and several mathematical models were used to take this complexity into account. This could provide information concerning the circumstances of overexposure. Concerning follow-up, the yield of dicentrics decreased by about 50% in the first 4 months following the end of overexposure whereas translocations were stable over the period of analysis. Conclusion: It has been useful to compare cytogenetic results with clinical results. The results presented here reveal good stability of translocations. However the first dose estimation was not attempted until 6 months after the last exposure. © 2006 Taylor & Francis.