The first gamma-H2AX biodosimetry intercomparison exercise of the developing European biodosimetry network RENEB.

In the event of a mass casualty radiation incident, the gamma-H2AX foci assay could be a useful tool to estimate radiation doses received by individuals. The rapid processing time of blood samples of just a few hours and the potential for batch processing, enabling high throughput, make the assay ideal for early triage categorisation to separate the 'worried well' from the low and critically exposed by quantifying radiation-induced foci in peripheral blood lymphocytes. Within the RENEB framework, 8 European laboratories have taken part in the first European gamma-H2AX biodosimetry exercise, which consisted of a telescoring comparison of 200 circulated foci images taken from 8 samples, and a comparison of 10 fresh blood lymphocyte samples that were shipped overnight to participating labs 4 or 24 h post-exposure. Despite large variations between laboratories in the dose-response relationship for foci induction, the obtained results indicate that the network should be able to use the gamma-H2AX assay for rapidly identifying the most severely exposed individuals within a cohort who could then be prioritised for accurate chromosome dosimetry.

Realising the European network of biodosimetry: RENEB-status quo.

Creating a sustainable network in biological and retrospective dosimetry that involves a large number of experienced laboratories throughout the European Union (EU) will significantly improve the accident and emergency response capabilities in case of a large-scale radiological emergency. A well-organised cooperative action involving EU laboratories will offer the best chance for fast and trustworthy dose assessments that are urgently needed in an emergency situation. To this end, the EC supports the establishment of a European network in biological dosimetry (RENEB). The RENEB project started in January 2012 involving cooperation of 23 organisations from 16 European countries. The purpose of RENEB is to increase the biodosimetry capacities in case of large-scale radiological emergency scenarios. The progress of the project since its inception is presented, comprising the consolidation process of the network with its operational platform, intercomparison exercises, training activities, proceedings in quality assurance and horizon scanning for new methods and partners. Additionally, the benefit of the network for the radiation research community as a whole is addressed.

Biological dosimetry assessments of a serious radiation accident in Bulgaria in 2011.

In 2011, a serious radiation accident occurred in Stamboliyski, Bulgaria, in an industrial sterilisation facility using very-high-activity (60)Co sources. For the five persons accidentally exposed, biological dosimetry based on dicentric analysis was performed in Sofia and in Paris, where the patients were transferred for treatment. Before completing the chromosomal dose assessment, and for the most exposed person, a preliminary cytogenetic evaluation based on electronically transmitted metaphase images was made. The averaged acute whole-body dose estimates for the five patients ranged from 5.2 to 1.2 Gy, and good agreement was obtained between the two laboratories. The patients were also assessed by their prodromal responses and depressed blood cell counts over the first week. The cytogenetic dose estimates were in good accord with those derived from the blood counts, and both techniques indicated that, for the two most seriously exposed persons both techniques indicated that the initial prodromal reactions had suggested somewhat less severe exposure.

Realising the European Network of Biodosimetry (RENEB).

In Europe, a network for biological dosimetry has been created to strengthen the emergency preparedness and response capabilities in case of a large-scale nuclear accident or radiological emergency. Through the RENEB (Realising the European Network of Biodosimetry) project, 23 experienced laboratories from 16 European countries will establish a sustainable network for rapid, comprehensive and standardised biodosimetry provision that would be urgently required in an emergency situation on European ground. The foundation of the network is formed by five main pillars: (1) the ad hoc operational basis, (2) a basis of future developments, (3) an effective quality-management system, (4) arrangements to guarantee long-term sustainability and (5) awareness of the existence of RENEB. RENEB will thus provide a mechanism for quick, efficient and reliable support within the European radiation emergency management. The scientific basis of RENEB will concurrently contribute to increased safety in the field of radiation protection.

Micronucleus test in buccal epithelium cells from patients subjected to panoramic radiography.

OBJECTIVES: To evaluate the possible genotoxic effect of radiation exposure for dental diagnostic purposes as measured by the formation of micronuclei. METHODS: The micronucleus test was applied to buccal epithelium cells, which are target cells for dental radiography. Specimens of exfoliated buccal cells were collected from patients subjected to panoramic radiography. Samples were obtained from 32 patients, 12 male and 20 female, aged from 24 years to 73 years, before and 10+/-2 days after panoramic radiation exposure. RESULTS: No significant increase in the frequency of cells with micronuclei and total number of micronuclei after panoramic tomography was detected. Mean values of buccal cells with micronuclei+/-standard deviation (SD) before and after radiation examination were 2.34+/-1.49% and 2.81+/-1.64%, respectively. A significant correlation between the age of investigated subjects and the initial frequency of micronuclei in buccal cells was observed (r=0.60, P<0.01). CONCLUSION: Panoramic radiographic examination does not induce micronuclei in target buccal epithelium cells.

Detection of aneugenic and clastogenic potential of X-rays, directly and indirectly acting chemicals in human hepatoma (Hep G2) and peripheral blood lymphocytes, using the micronucleus assay and fluorescent in situ hybridization with a DNA centromeric probe.

In human hepatoma (Hep G2) cells and peripheral blood lymphocytes (HPBL) the cytokinesis-blocked micronuclei (MN) and fluorescent in situ hybridization (FISH) assays were applied to study aneugenic and clastogenic potentials of X-rays, directly and indirectly acting chemicals. Induction of MN was studied in vitro following treatment with X-rays, directly acting chemicals, such as methylmeth-anesulphonate (MMS), colchicine (COL), vincristine sulphate (VCS) and vinblastine sulphate (VBS), and indirectly acting agents, such as cyclophosphamide (CP), hexamethylphosphoramide (HMPA), 2-acetylaminofluorene (2-AAF) and 4-acetylaminofluorene (4-AAF). Depending on the presence of the fluorescent signal in the MN following FISH with a human DNA centromeric probe, MN in the binucleated Hep G2 cells and lymphocytes were scored as centromere-positive or centromere-negative, representing an aneugenic and clastogenic event respectively. In the controls approximately 50% of spontaneously occurring MN were centromere-positive. Treatment of human hepatoma cells and HPBL (in vitro) with potent aneugens such as COL, VCS and VBS increased the number of MN in a dose-dependent manner; of these 75-93% were centromere-positive. X-irradiation induced MN in a dose-related manner in binucleated Hep G2 cells and HPBL, of which 33-40% were centromere-positive, which demonstrates the significant aneugenic potentials of X-rays. Strong clastogenic activity was observed with MMS and frequency of centromere-positive MN was low: approximately 20 and 30% for HPBL and Hep G2 cells respectively. In Hep G2 cells significant aneugenic activity was found with indirectly acting promutagens/procarcinogens such as HMPA and 2-AAF, in contrast to CP, which came out as a potent clastogen. The non-carcinogen 4-AAF was not able to induce an increase in the frequency of MN in Hep G2 cells. All indirectly acting chemicals tested came out negative when HPBL were used as targets for DNA damage. The results presented correlate positively with data from in vivo assays and indicate that the Hep G2 cell system is a suitable bioactivation system (in vitro) for evaluating the clastogenic and aneugenic potentials of chemicals which require exogenous metabolic activations in order to exert their mutagenic potential.