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Radiation protection dosimetry, 182, 139--145


Balajee, Adayabalam S, Smith, Tammy, Ryan, Terri, Escalona, Maria, Dainiak, Nicholas

Use of ionizing radiation (IR) in various industrial, medical and other applications can potentially increase the risk of medical, occupational or accidental human exposure. Additionally, in the event of a radiological or nuclear (R/N) incident, several tens of hundreds and thousands of people are likely to be exposed to IR. IR causes serious health effects including mortality from acute radiation syndrome and therefore it is imperative to determine the absorbed radiation dose, which will enable physicians in making an appropriate clinical 'life-saving' decision. The 'Dicentric Chromosome Assay (DCA)' is the gold standard for estimating the absorbed radiation dose but its performance is time consuming and laborious. Further, timely evaluation of dicentric chromosomes (DCs) for dose estimation in a large number of samples provides a bottleneck because of a limited number of trained personnel and a prolonged time for manual analysis. To circumvent some of these technical issues, we developed and optimized a miniaturized high throughput version of DCA (mini-DCA) in a 96-microtube matrix with bar-coded 1.4 ml tubes to enable the processing of a large number of samples. To increase the speed of DC analysis for radiation dose estimation, a semi-automated scoring was optimized using the Metafer DCScore algorithm. The accuracy of mini-DCA in dose estimation was verified and validated though comparison with conventional DCA performed in 15 ml conical tubes. The mini-DCA considerably reduced the sample processing time by a factor of 4 when compared to the conventional DCA. Further, the radiation doses estimated by mini-DCA using the triage mode of scoring (50 cells or 30 DCs) were similar to that of conventional DCA using 300-500 cells. The mini-DCA coupled with semi-automated DC scoring not only reduced the sample processing and analysis times by a factor of 4 but also enabled the processing of a large number of samples at once. Our mini-DCA method, once automated for high throughput robotic platforms, will be an effective radiological triage tool for mass casualty incidents.

Digital object identifier (DOI): 10.1093/rpd/ncy127

International journal of radiation biology, 93, 48--57

Dose assessment intercomparisons within the RENEB network using G0-lymphocyte prematurely condensed chromosomes (PCC assay).

Terzoudi, Georgia I, Pantelias, Gabriel, Darroudi, Firouz, Barszczewska, Katarzyna, Buraczewska, Iwona, Depuydt, Julie, Georgieva, Dimka, Hadjidekova, Valeria, Hatzi, Vasiliki I, Karachristou, Ioanna, Karakosta, Maria, Meschini, Roberta, M'Kacher, Radhia, Montoro, Alegria, Palitti, Fabrizio, Pantelias, Antonio, Pepe, Gaetano, Ricoul, Michelle, Sabatier, Laure, Sebastià, Natividad, Sommer, Sylwester, Vral, Anne, Zafiropoulos, Demetre, Wojcik, Andrzej

Dose assessment intercomparisons within the RENEB network were performed for triage biodosimetry analyzing G0-lymphocyte PCC for harmonization, standardization and optimization of the PCC assay. Comparative analysis among different partners for dose assessment included shipment of PCC-slides and captured images to construct dose-response curves for up to 6 Gy γ-rays. Accident simulation exercises were performed to assess the suitability of the PCC assay by detecting speed of analysis and minimum number of cells required for categorization of potentially exposed individuals. Calibration data based on Giemsa-stained fragments in excess of 46 PCC were obtained by different partners using galleries of PCC images for each dose-point. Mean values derived from all scores yielded a linear dose-response with approximately 4 excess-fragments/cell/Gy. To unify scoring criteria, exercises were carried out using coded PCC-slides and/or coded irradiated blood samples. Analysis of samples received 24 h post-exposure was successfully performed using Giemsa staining (1 excess-fragment/cell/Gy) or centromere/telomere FISH-staining for dicentrics. Dose assessments by RENEB partners using appropriate calibration curves were mostly in good agreement. The PCC assay is quick and reliable for whole- or partial-body triage biodosimetry by scoring excess-fragments or dicentrics in G0-lymphocytes. Particularly, analysis of Giemsa-stained excess PCC-fragments is simple, inexpensive and its automation could increase throughput and scoring objectivity of the PCC assay.

Digital object identifier (DOI): 10.1080/09553002.2016.1234725

Radiat Prot Dosimetry
July, 2016

A New Cytogenetic Biodosimetry Image Repository for the Dicentric Assay.

Romm, Horst, Beinke, Christina, Garcia, Omar, Di Giorgio, Marina, Gregoire, Eric, Livingston, Gordon, Lloyd, David, Martinez-Lopez, Wilner, Moquet, Jayne E., Sugarman, Stephen L., Wilkins, Ruth C., Ainsbury, Elizabeth A.

The BioDoseNet was founded by the World Health Organization as a global network of biodosimetry laboratories for building biodosimetry laboratory capacities in countries. The newly established BioDoseNet image repository is a databank of ~25 000 electronically captured images of metaphases from the dicentric assay, which have been previously analysed by international experts. The detailed scoring results and dose estimations have, in most cases, already been published. The compilation of these images into one image repository provides a valuable tool for training and research purposes in biological dosimetry. No special software is needed to view and score the image galleries. For those new to the dicentric assay, the BioDoseNet Image Repository provides an introduction to and training for the dicentric assay. It is an excellent instrument for intra-laboratory training purposes or inter-comparisons between laboratories, as recommended by the International Organization for Standardisation standards. In the event of a radiation accident, the repository can also increase the surge capacity and reduce the turnaround time for dose estimations. Finally, it provides a mechanism for the discussion of scoring discrepancies in difficult cases.

Digital object identifier (DOI): 10.1093/rpd/ncw158

Int J Radiat Biol, 1–3
May, 2016

Realizing the European Network of Biodosimetry (RENEB) - concluding remarks.

Lloyd, David, Turai, István, Voisin, Philippe

Digital object identifier (DOI): 10.1080/09553002.2016.1178866

Radiat Environ Biophys
March, 2016

Chromosome aberrations in Japanese fishermen exposed to fallout radiation 420-1200~km distant from the nuclear explosion test site at Bikini Atoll: report 60~years after the incident.

Tanaka, Kimio, Ohtaki, Megu, Hoshi, Masaharu

During the period from March to May, 1954, the USA conducted six nuclear weapon tests at the "Bravo" detonation sites at the Bikini and Enewetak Atolls, Marshall Islands. At that time, the crew of tuna fishing boats and cargo ships that were operating approximately 150-1200 km away from the test sites were exposed to radioactive fallout. The crew of the fishing boats and those on cargo ships except the "5th Fukuryu-maru" did not undergo any health examinations at the time of the incident. In the present study, chromosome aberrations in peripheral blood lymphocytes were examined in detail by the G-banding method in 17 crew members from 8 fishing boats and 2 from one cargo ship, 60 years after the tests. None of the subjects examined had suffered from cancer. The percentages of both stable-type aberrations such as translocation, inversion and deletion, and unstable-type aberrations such as dicentric and centric ring in the study group were significantly higher (1.4- and 2.3-fold, respectively) than those in nine age-matched controls. In the exposed and control groups, the percentages of stable-type aberrations were 3.35 \% and 2.45 \%, respectively, and the numbers of dicentric and centric ring chromosomes per 100 cells were 0.35 and 0.15, respectively. Small clones were observed in three members of the exposed group. These results suggest that the crews were exposed to slightly higher levels of fallout than had hitherto been assumed.

Digital object identifier (DOI): 10.1007/s00411-016-0648-3

Public Health England. Part of: Radiation: PHE-CRCE report series.

Doses in Radiation Accidents Investigated by Chromosomal Aberration Analysis XXV. Review of cases investigated, 2006–2015.

M Sun, J E Moquet, S Barnard, D C Lloyd, K Rothkamm, E A Ainsbury

During the period 73 people suspected of being overexposed to ionising radiation were referred to Public Health England (and its predecessor the Health Protection Agency) for biological dosimetry. Although the vast majority of cases were suspected occupational overexposures, the most serious case concerned a 2-year-old boy who sustained radiation burns during CT scans performed outside the European Union, which were incorrectly repeated numerous times. The cases included in this summary bring the total number of individuals examined since the laboratory was established in 1968 to 1092. A number of new biological dosimetry techniques have been developed within the last 10 years. These are briefly summarised in this report and represent a large improvement in the laboratory’s ability both to perform accurate routine biological dose estimations and to provide rapid response triage dose estimates following a mass casualty event.

Int J Radiat Biol, 90(2), 193--202
February, 2014

Inter- and intra-laboratory comparison of a multibiodosimetric approachto triage in a simulated, large scale radiation emergency.

Elizabeth A. Ainsbury, Jenna Al-Hafidh, Ainars Bajinskis, Stephen Barnard, Joan Francesc Barquinero, Christina Beinke, Virginie {de Gelder}, Eric Gregoire, Alicja Jaworska, Carita Lindholm, David Lloyd, Jayne Moquet, Reetta Nylund, Ursula Oestreicher, Sandrine Roch-Lef{\'e}vre, Kai Rothkamm, Horst Romm, Harry Scherthan, Sylwester Sommer, Hubert Thierens, Charlot Vandevoorde, Anne Vral, Andrzej Wojcik

The European Union's Seventh Framework Programme-funded project 'Multi-disciplinary biodosimetric tools to manage high scale radiological casualties' (MULTIBIODOSE) has developed a multiparametric approach to radiation biodosimetry, with a particular emphasis on triage of large numbers of potentially exposed individuals following accidental exposures. In November 2012, an emergency exercise took place which tested the capabilities of the MULTIBIODOSE project partners. The exercise described here had a dual purpose: Intercomparison of (i) three biodosimetric assays, and (ii) the capabilities of the seven laboratories, with regards to provision of triage status for suspected radiation exposed individuals.Three biological dosimetry tools - the dicentric, micronucleus and gamma-H2AX (the phosphorylated form of member X of histone H2A, in response to DNA double-strand breaks) foci assays - were tested, in addition to provision of the triage status results (low exposure: 2 Gy) by the MULTIBIODOSE software. The exercise was run in two modes: An initial triage categorisation of samples (based on the first dose estimates for each assay received from each laboratory) followed by collation of the full set of estimated doses (all the results from all modes of each assay carried out by the participating laboratories) calculated using as many modes of operation as possible of the different assays developed during the project. Simulated acute whole body and partial body exposures were included.The results of the initial triage categorisation and the full comparison of assays and methods within and between laboratories are presented here.The data demonstrate that the MULTIBIODOSE approach of applying multiparametric tools to radiation emergencies is valid and effective.

Health Phys, 105(4), 366--373
October, 2013

Biodosimetry of restoration workers for the Tokyo Electric PowerCompany (TEPCO) Fukushima Daiichi nuclear power station accident.

Yumiko Suto, Momoki Hirai, Miho Akiyama, Gen Kobashi, Masanari Itokawa, Makoto Akashi, Nobuyuki Sugiura

The biological dose of nuclear workers engaged in emergency response tasks at Tokyo Electric Power Company (TEPCO) Fukushima Daiichi Nuclear Power Station was estimated in the present study. As the national core center for radiation emergency medical preparedness in Japan, the National Institute of Radiological Sciences (NIRS) received all individuals who were suspected of being overexposed to acute radiation. In the course of health examinations at NIRS, biological dosimetry was performed by the dicentric chromosome assay (DCA). Twelve individuals were examined from 21 March-1 July 2011. The results indicated that the estimated exposure doses for all individuals were lower than 30 mGy, with the mean value of about 101 mGy. These results by DCA were in accordance with those obtained by physical dosimetry based on personal dosimeter recording assessment. The results corroborate the fact that no acute radiation syndrome was observed among the workers examined.

Radiat Res
July, 2013

NATO DOSIMETRY STUDY: Laboratory Intercomparison of the Dicentric Chromosome Analysis Assay.

C. Beinke, S. Barnard, H. Boulay-Greene, A. {De Amicis}, S. {De Sanctis}, F. Herodin, A. Jones, U. Kulka, F. Lista, D. Lloyd, P. Martigne, J. Moquet, U. Oestreicher, H. Romm, K. Rothkamm, M. Valente, V. Meineke, H. Braselmann, M. Abend

The study design and obtained results represent an intercomparison of various laboratories performing dose assessment using the dicentric chromosome analysis (DCA) as a diagnostic triage tool for individual radiation dose assessment. Homogenously X-irradiated (240 kVp, 1 Gy/min) blood samples for establishing calibration data (0.25-5 Gy) as well as blind samples (0.1-6.4 Gy) were sent to the participants. DCA was performed according to established protocols. The time taken to report dose estimates was documented for each laboratory. Additional information concerning laboratory organization/characteristics as well as assay performance was collected. The mean absolute difference (MAD) was calculated and radiation doses were merged into four triage categories reflecting clinical aspects to calculate accuracy, sensitivity and specificity. The earliest report time was 2.4 days after sample arrival. DCA dose estimates were reported with high and comparable accuracy, with MAD values ranging between 0.16-0.5 Gy for both manual and automated scoring. No significant differences were found for dose estimates based either on 20, 30, 40 or 50 cells, suggesting that the scored number of cells can be reduced from 50 to 20 without loss of precision of triage dose estimates, at least for homogenous exposure scenarios. Triage categories of clinical significance could be discriminated efficiently using both scoring procedures.

Mutat Res
May, 2013

Automatic scoring of dicentric chromosomes as a tool in large scale radiation accidents.

H. Romm, E. Ainsbury, S. Barnard, L. Barrios, J. F. Barquinero, C. Beinke, M. Deperas, E. Gregoire, A. Koivistoinen, C. Lindholm, J. Moquet, U. Oestreicher, R. Puig, K. Rothkamm, S. Sommer, H. Thierens, V. Vandersickel, A. Vral, A. Wojcik

Mass casualty scenarios of radiation exposure require high throughput biological dosimetry techniques for population triage in order to rapidly identify individuals who require clinical treatment. The manual dicentric assay is a highly suitable technique, but it is also very time consuming and requires well trained scorers. In the framework of the MULTIBIODOSE EU FP7 project, semi-automated dicentric scoring has been established in six European biodosimetry laboratories. Whole blood was irradiated with a Co-60 gamma source resulting in 8 different doses between 0 and 4.5Gy and then shipped to the six participating laboratories. To investigate two different scoring strategies, cell cultures were set up with short term (2-3h) or long term (24h) colcemid treatment. Three classifiers for automatic dicentric detection were applied, two of which were developed specifically for these two different culture techniques. The automation procedure included metaphase finding, capture of cells at high resolution and detection of dicentric candidates. The automatically detected dicentric candidates were then evaluated by a trained human scorer, which led to the term 'semi-automated' being applied to the analysis. The six participating laboratories established at least one semi-automated calibration curve each, using the appropriate classifier for their colcemid treatment time. There was no significant difference between the calibration curves established, regardless of the classifier used. The ratio of false positive to true positive dicentric candidates was dose dependent. The total staff effort required for analysing 150 metaphases using the semi-automated approach was 2min as opposed to 60min for manual scoring of 50 metaphases. Semi-automated dicentric scoring is a useful tool in a large scale radiation accident as it enables high throughput screening of samples for fast triage of potentially exposed individuals. Furthermore, the results from the participating laboratories were comparable which supports networking between laboratories for this assay.

Hong Kong Med J, 19(2), 168--173
April, 2013

Cytogenetic biodosimetry: what it is and how we do it.

K. F. Wong, Lisa L P. Siu, E. Ainsbury, J. Moquet

Dicentric assay is the international gold standard for cytogenetic biodosimetry after radiation exposure, despite being very labour-intensive, time-consuming, and highly expertise-dependent. It involves the identification of centromeres and structure of solid-stained chromosomes and the enumeration of dicentric chromosomes in a large number of first-division metaphases of cultured T lymphocytes. The dicentric yield is used to estimate the radiation exposure dosage according to a statistically derived and predetermined dose-response curve. It can be used for population triage after large-scale accidental over-exposure to ionising radiation or with a view to making clinical decisions for individual patients receiving substantial radiation. In this report, we describe our experience in the establishment of a cytogenetic biodosimetry laboratory in Queen Elizabeth Hospital, Hong Kong. This was part of the contingency plan for emergency measures against radiation accidents at nuclear power stations.

Int J Radiat Biol, 89(3), 191--199
March, 2013

The dose-response relationship for dicentric chromosomes and γ-H2AX foci in human peripheral blood lymphocytes: Influence of temperature during exposure and intra- and inter-individual variability of donors

Halina Lisowska, Aneta Wegierek-Ciuk, Anna Banasik-Nowak, Janusz Braziewicz, Maria Wojewodzka, Andrzej Wojcik, Anna Lankoff

Purpose: Hypothermia during in vitro irradiation of human peripheral blood lymphocytes (PBL) affects the level of chromosome aberrations. The molecular mechanisms of this phenomenon are not fully understood. The aim of our study was to examine the effect of hypothermia on the dose-response relationship for dicentric chromosomes and the level of γ-H2AX (phosphorylated histone H2AX) foci. In addition, the inter- and intra-individual variability was assessed in relation to temperature. Materials and methods: PBL were kept at 0.8, 20 and 37°C and then exposed to gamma-rays (from 0–3 Gy). Dicentric chromosomes were scored in first post-treatment mitoses. γ-H2AX foci were scored 15, 30, 60, 120 min and 24 h post irradiation. Results: Our results revealed that the frequency of dicentric chromosomes in cells exposed at 37°C to gamma-rays was higher than after exposure at 0.8 and 20°C. No effect of temperature was observed on the number of γ-H2AX foci as well as on the intra- and inter-individual variations of the dicentric yield and the number of γ-H2AX foci. Conclusions: Temperature at exposure to ionizing radiation has a pronounced effect on the level of cytogenetic damage but not γ-H2AX foci.

Digital object identifier (DOI): 10.3109/09553002.2013.741284

Radiat Res, 178(4), 357--364
October, 2012

Detection of partial-body exposure to ionizing radiation by the automaticdetection of dicentrics.

Aurelie Vaurijoux, Eric Gregoire, Sandrine Roch-Lefevre, Pascale Voisin, Cecile Martin, Philippe Voisin, Laurence Roy, Gaetan Gruel

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.

Radiat Prot Dosimetry, epub, epub
August, 2012


O. Garc{\'i}a, M. {Di Giorgio}, M. B. Vallerga, A. Radl, M. R. Taja, A. Seoane, J. {De Luca}, M. {Stuck Oliveira}, P. Valdivia, A. I. Lamadrid, J. E. Gonz{\'a}lez, I. Romero, T. Mandina, G. Pantelias, G. Terzoudi, C. Guerrero-Carbajal, C. {Arceo Maldonado}, M. Espinoza, N. Oliveros, W. Mart{\'i}nez-L{\'o}pez, M. V. {Di Tomaso}, L. M{\'e}ndez-Acu{\~n}a, R. Puig, L. Roy, J. F. Barquinero

The bottleneck in data acquisition during biological dosimetry based on a dicentric assay is the need to score dicentrics in a large number of lymphocytes. One way to increase the capacity of a given laboratory is to use the ability of skilled operators from other laboratories. This can be done using image analysis systems and distributing images all around the world. Two exercises were conducted to test the efficiency of such an approach involving 10 laboratories. During the first exercise (E1), the participant laboratories analysed the same images derived from cells exposed to 0.5 and 3 Gy; 100 images were sent to all participants for both doses. Whatever the dose, only about half of the cells were complete with well-spread metaphases suitable for analysis. A coefficient of variation (CV) on the standard deviation of ?15 \% was obtained for both doses. The trueness was better for 3 Gy (0.6 \%) than for 0.5 Gy (37.8 \%). The number of estimated doses classified as satisfactory according to the z-score was 3 at 0.5 Gy and 8 at 3 Gy for 10 dose estimations. In the second exercise, an emergency situation was tested, each laboratory was required to score a different set of 50 images in 2 d extracted from 500 downloaded images derived from cells exposed to 0.5 Gy. Then the remaining 450 images had to be scored within a week. Using 50 different images, the CV on the estimated doses (79.2 \%) was not as good as in E1, probably associated to a lower number of cells analysed (50 vs. 100) or from the fact that laboratories analysed a different set of images. The trueness for the dose was better after scoring 500 cells (22.5 \%) than after 50 cells (26.8 \%). For the 10 dose estimations, the number of doses classified as satisfactory according to the z-score was 9, for both 50 and 500 cells. Overall, the results obtained support the feasibility of networking using electronically transmitted images. However, before its implementation some issues should be elucidated, such as the number and resolution of the images to be sent, and the harmonisation of the scoring criteria. Additionally, a global website able to be used for the different regional networks, like Share Points, will be desirable to facilitate worldwide communication.

Mutat Res, 751(2), 258--286

Ionizing radiation biomarkers for potential use in epidemiologicalstudies.

Eileen Pernot, Janet Hall, Sarah Baatout, Mohammed Abderrafi Benotmane, Eric Blanchardon, Simon Bouffler, Houssein {El Saghire}, Maria Gomolka, Anne Guertler, Mats Harms-Ringdahl, Penny Jeggo, Michaela Kreuzer, Dominique Laurier, Carita Lindholm, Radhia Mkacher, Roel Quintens, Kai Rothkamm, Laure Sabatier, Soile Tapio, Florent {de Vathaire}, Elisabeth Cardis

Ionizing radiation is a known human carcinogen that can induce a variety of biological effects depending on the physical nature, duration, doses and dose-rates of exposure. However, the magnitude of health risks at low doses and dose-rates (below 100mSv and/or 0.1mSvmin(-1)) remains controversial due to a lack of direct human evidence. It is anticipated that significant insights will emerge from the integration of epidemiological and biological research, made possible by molecular epidemiology studies incorporating biomarkers and bioassays. A number of these have been used to investigate exposure, effects and susceptibility to ionizing radiation, albeit often at higher doses and dose rates, with each reflecting time-limited cellular or physiological alterations. This review summarises the multidisciplinary work undertaken in the framework of the European project DoReMi (Low Dose Research towards Multidisciplinary Integration) to identify the most appropriate biomarkers for use in population studies. In addition to logistical and ethical considerations for conducting large-scale epidemiological studies, we discuss the relevance of their use for assessing the effects of low dose ionizing radiation exposure at the cellular and physiological level. We also propose a temporal classification of biomarkers that may be relevant for molecular epidemiology studies which need to take into account the time elapsed since exposure. Finally, the integration of biology with epidemiology requires careful planning and enhanced discussions between the epidemiology, biology and dosimetry communities in order to determine the most important questions to be addressed in light of pragmatic considerations including the appropriate population to be investigated (occupationally, environmentally or medically exposed), and study design. The consideration of the logistics of biological sample collection, processing and storing and the choice of biomarker or bioassay, as well as awareness of potential confounding factors, are also essential.

Mutat Res, 699(1-2), 29--34
June, 2010

Frequency of chromosomal aberrations in Prague mothers and theirnewborns.

A. Rossnerova, I. Balascak, P. Rossner, R. J. Sram

The capital city of Prague is one of the most polluted areas of the Czech Republic. The impact of air pollution on the level of chromosomal aberrations was systematically studied: analyses were performed using fluorescence in situ hybridization (FISH) with whole-chromosome painting for chromosomes #1 and #4. In the present study, we analyzed the levels of stable (one-way and two-way translocations) and unstable (acentric fragments) chromosomal aberrations in 42 mothers living in Prague and in their newborns. The average age of the mothers was 29 years (range, 20-40 years). Blood samples were collected from October 2007 to February 2008. The average levels of carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) and benzo[a]pyrene (B[a]P) in respirable particles (PM2.5), as determined by stationary monitoring, were 21.0+/-12.3ng/m(3) and 2.9+/-1.8ng/m(3), respectively. We did not observe any effect of either c-PAH or B[a]P exposure on the genomic frequency of translocations (per 100 cells, F(G)/100) in either group due to their similar exposure during the winter months. The mean values of F(G)/100 representing stable aberrations were 0.09+/-0.13 vs 0.80+/-0.79 (p

Pharmacogen Genom, 16, 87- 99

Cytogenmetic biomarkers, urinary metabolites and metabolic gene polymorphisms in workers exposed to styrene.

L. Migliore, A. Naccarati, F. Copped{\`e}, E. Bergamaschi, G. De Palma, A. Voho, P. Manini, H. J{\"a}rventaus, A. Mutti, H. Norppa, A. Hirvonen

The present study comprised a biomonitoring study in 95 workers occupationally exposed to styrene and 98 unexposed controls, employing an integrated approach involving biomarkers of exposure, effect, and susceptibility. Airborne styrene was evaluated at workplace, and urinary styrene metabolites, mandelic acid (MA), phenylglyoxylic acid (PGA), vinylphenols (VPTs) and phenylhydroxyethylmercapturic acids (PHEMAs), were measured as biomarkers of internal dose. Cytogenetic alterations were evaluated by analysing the frequency of chromosomal aberrations (CAs) and micronucleated binucleated cells (MNBN) in peripheral blood lymphocytes. The micronucleus assay was coupled with centromeric fluorescence in situ hybridization to distinguish micronuclei (MN) arising from chromosomal breakage (C- MN) from those harboring whole chromosomes (C+ MN). The possible influence of genetic polymorphisms of xenobiotic-metabolizing enzymes involved in styrene biotransformation (EPHX1, GSTT1, GSTM1, GSTP1) and NAT2 on the cytogenetic endpoints was investigated. The exposed workers showed a significantly higher frequency of MNBN (13.8+/-0.5% versus 9.2+/-0.4%; P<0.001) compared to control subjects. The effect appeared to concern both C- and C+ MN. A positive correlation was seen between the frequency of C+ MN and urinary level of MA+PGA (P<0.05) and VPTs (P<0.001). Chromosome-type CAs positively correlated with airborne styrene level and VPTs (P<0.05), whereas chromatid-type CAs correlated with PHEMAs (P<0.05). Workers bearing GSTM1 null genotype showed lowered levels of PHEMAs (P<0.001). The GSTT1 null genotype was associated with increased MNBN frequencies in the exposed workers (P<0.05) and the fast activity EPHX genotype with a moderate decrease in both MNBN and CAs in the controls. Our results suggest that occupational exposure to styrene has genotoxic effects that are potentiated by the GSTT1 gene deletion. These observations may have relevance considering the risk of lymphatic and haematopoietic malignancies tentatively associated with styrene exposure.

Cytogenet Genome Res, 104, 383- 389

New developments in automated cytogenetic imaging: unattended scoring of dicentric chromosomes, micronuclei, single cell electrophoresis, and fluorescence signals.

C. Schunck, T. Johannes, D. Varga, T. L{\"o}rch, A. Plesch

The quantification of DNA damage, both in vivo and in vitro, can be very time consuming, since large amounts of samples need to be scored. Additional uncertainties may arise due to the lack of documentation or by scoring biases. Image analysis automation is a possible strategy to cope with these difficulties and to generate a new quality of reproducibility. In this communication we collected some recent results obtained with the automated scanning platform Metafer, covering applications that are being used in radiation research, biological dosimetry, DNA repair research and environmental mutagenesis studies. We can show that the automated scoring for dicentric chromosomes, for micronuclei, and for Comet assay cells produce reliable and reproducible results, which prove the usability of automated scanning in the above mentioned research fields.

Radioprotection, 38, 323- 340

Comparaison de syst{\`e}mes d'analyse d'images cytologiques en dosim{\'e}trie biologique (FRENCH)

L. Roy, M. Delbos, N. Paillole, V. Durand, P. Voisin

La technique de référence en dosimétrie biologique est basée sur le dénombrement des aberrations chromosomiques de type dicentrique induit par les rayonnements ionisants. Cet article présente divers systèmesd'analyse d'images utilisés en dosimétrie biologique pour aider la détection de ces aberrations. Les systèmes présentés sont le CYTOGEN de la société IMSTAR, le CYTOSCAN (APPLIED IMAGING) et le METAFER (METASYSTEM). Tous ne présentent pas les mêmes fonctionnalités et chacun peut être utilisé de façon plus ou moins automatique. Certaines fonctionnalités communes de ces systèmes sont comparées. L'aide apportée par les systèmes porte sur 3 points : (1) localisation automatique des métaphases sur les lames, dans ce cas on a un gain de temps d'un facteur 2 à 4 par rapport au comptage manuel ; (2) un outil d'aide au comptage qui apporte un confort de lecture et une meilleure fiabilité des résultats ; (3) la détection automatique des dicentriques est particulièrement utile en cas de tri de population. En effet, dans ce cas il faut estimer très rapidement la dose reçue par un nombre important de personnes. Par contre, l'estimation de dose n'a pas besoin d'être aussi précise que dans le cas de l'expertise individuelle. Des erreurs dans la détection des dicentriques est alors tolérée et une détection automatique des dicentriques est envisageable. Le gain de temps est très appréciable puisqu'il est possible de compter 300 cellules en une demie-heure (METAFER) contre 25 avec la seule aide du chercheur de métaphases. Cependant la qualité de la détection doit encore être améliorée puisque 50 % des dicentriques ne sont pas détectées. Le marquage des centromères par technique FISH devrait permettre d'améliorer la sensibilité de la technique. Les premiers résultats sont encourageant puisque 90 % des centromères sont correctements détectés mais d'autres expériences doivent êtres réalisées pour évaluer le gain de temps.