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.

Recent developments in the assessment of chromosomal damage.

Ionizing radiation and restriction endonucleases are very efficient in inducing chromosomal aberrations (CAs). These aberrations are mainly consequences of misrepair of DNA double-strand breaks (DSBs). The fast repairing component of DSBs induced by ionizing radiation seems to be responsible for exchange aberration. Use of premature chromosome condensation technique in combination with DNA repair inhibitors such as ara A has given valuable information on the assessment of the frequencies of initial chromosome breaks and the kinetics of their repair following low LET radiation. The recently developed 'chromosome painting' technique using chromosome-specific libraries has also increased considerably the resolution of identifying and scoring of CAs. After low LET radiation, stable chromosome exchanges (translocations) are induced more frequently than unstable chromosome exchanges (dicentrics). Fluorescence in situ hybridization employing telomeric probe has made it possible to score efficiently exchange aberrations involving the acrocentric chromosomes of mouse. Chinese hamster cells have several intercalary telomeric sequences present in most of the chromosomes. These telomeric blocks have been found to be associated with chromosomal aberrations induced by restriction endonucleases and short wave UV and evidence has been obtained for apparent amplification of telomeric sequences at the break points.

Genotoxic effects of sodium arsenite on human cells.

The effects of sodium arsenite (SA) were studied either alone or in combination with X-rays in peripheral blood lymphocytes, and with short-wave ultraviolet (UV) radiation in primary human fibroblast culture systems. It was found that SA (i) inhibited the cell cycle progression of phytohaemagglutinin (PHA)-responsive lymphocytes, (ii) induced chromatid-type aberrations and sister-chromatid exchanges (SCEs) as a function of concentration and (iii) potentiated the X-ray- and UV-induced chromosomal damage. Our results suggest that SA interferes with the DNA repair process, presumably by inhibiting the ligase activity. This accounted for an increase in the DNA replication-dependent processes, chromatid aberrations and SCEs and synergistic enhancement of the X-ray- and UV-induced chromosomal damage. This ability of arsenite may be responsible for its comutagenic properties with different types of mutagens and hence its carcinogenicity.