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Purpose: Identification of early radiation response genes (ERG) in human lymphocytes after γ-irradiation by using the whole-human-genome DNA-microarrays and the evaluation of their possible role in rapid radiation biodosimetry by applying real-time quantitative polymerase chain reaction (RT-qPCR) methodology for validation in a small group of human individuals. Materials and methods: Whole blood from a healthy human donor was exposed at 37°C to 137Cs γ-radiations (absorbed dose: 1-4 Gy). Fifteen minutes following irradiation the lymphocytes were isolated from the blood (for 2 h at 20°C) and their gene expression was investigated using the DNA-microarrays. Subsequently, 14 genes were selected and validated using the TaqMan™ probes based upon the RT-qPCR assay within a group of 6 human donors. Results: A dose-related relative change in quantitative gene expression using the DNA-microarray assay was demonstrated in 24 of 102 genes. Up-regulation of expression was observed in 15 genes: CD69 (CD69 molecule), CDKN1A (cyclin-dependent kinase inhibitor 1A), EGR1 (early growth response 1), EGR4 (early growth response 4), FLJ35725 (chromosome 4 ORF 23), hCG2041177 (hCG - human Celera® Genome), hCG1643466.2, IFN-γ (interferon-γ), ISG20L (interferon stimulated exonuclease gene 20 kDa - like 1), c-JUN (jun oncogene), MDM2 (mouse double minute 2), MUC5B (mucine), PLK2 (polo-like kinase 2), RND1 (rho-family GTPase 1) and TNFSF9 (tumour necrosis factor superfamily member 9). Down-regulation of expression was found in the remaining nine genes: GRIK3 (glutamate receptor ionotropic kainate 3), hCG1985174, hCG1998530, hCG2038519, OCLN (occludin), RPL10A (ribosomal protein L10a), SERHL2 (serine hydrolase-like 2), SGK3 (serum/glucocorticoid regulated kinase 3) and STARD13 (START domain containing 13). Conclusion: A significant correlation between absorbed radiation dose and change in relative gene expression was particularly evident for EGR1, EGR4, IFN-γ, c-JUN and TNFSF9 (p ≤ 0.05). Results warrant the further investigation of these ERG as potential biodosimetric markers. [ABSTRACT FROM AUTHOR]

Purpose: This collaboration of five established European gene expression labs investigated the potential impact of culture conditions on the transcriptional response of peripheral blood to radiation exposure., Materials and Methods: Blood from one healthy donor was exposed ex vivo to a Cobalt 60 source to produce a calibration curve in addition to four unknown doses. After exposure, the blood samples were either diluted with RPMI medium or left untouched. After 24-h incubation at 37 °C the diluted blood samples were lysed, while the undiluted samples were mixed with the preservative RNALater and all samples were shipped frozen to the participating labs. Samples were processed by each lab using microarray (one lab) and QRT-PCR (four labs)., Results: We show that although culture conditions affect the total amount of RNA recovered (p < .0001) and its integrity (p < .0001), it does not significantly affect dose estimates (except for the true dose at 1.1 Gy). Most importantly, the different analysis approaches provide comparable mean absolute difference of estimated doses relative to the true doses (p = .9) and number of out of range (>0.5 Gy) measurements (p = .6)., Conclusion: This study confirms the robustness of gene expression as a method for biological dosimetry.

Purpose: RENEB, 'Realising the European Network of Biodosimetry and Physical Retrospective Dosimetry,' is a network for research and emergency response mutual assistance in biodosimetry within the EU. Within this extremely active network, a number of new dosimetry methods have recently been proposed or developed. There is a requirement to test and/or validate these candidate techniques and inter-comparison exercises are a well-established method for such validation., Materials and Methods: The authors present details of inter-comparisons of four such new methods: dicentric chromosome analysis including telomere and centromere staining; the gene expression assay carried out in whole blood; Raman spectroscopy on blood lymphocytes, and detection of radiation-induced thermoluminescent signals in glass screens taken from mobile phones., Results: In general the results show good agreement between the laboratories and methods within the expected levels of uncertainty, and thus demonstrate that there is a lot of potential for each of the candidate techniques., Conclusions: Further work is required before the new methods can be included within the suite of reliable dosimetry methods for use by RENEB partners and others in routine and emergency response scenarios.

DNA-associated Auger electron emitters (AEE) cause cellular damage leading to high-LET type cell survival curves indicating an enhanced relative biological effectiveness. Double strand breaks (DSBs) induced by Iodine-125-deoxyuridine ((125)I-UdR) decays are claimed to be very complex. To elucidate the assumed genotoxic potential of (125)I-UdR, chromatid aberrations were analysed in exposed human peripheral blood lymphocytes (PBL). PBL were stimulated with medium containing phytohaemagglutinin (PHA). After 24h, cultures were labelled with (125)I-UdR for 18h (activity concentration 1-45 kBq) during the S-phase. Following standard cytogenetic procedure, at least 100 metaphases were analysed microscopically for each activity concentration. Cell death was measured by apoptosis assay using flow cytometry. Radiation doses were determined by using point kernel calculations. After 18h labelling with (125)I-UdR the cell cycle distribution is severely disturbed. About 40% of PBL are fully labelled and 20% show a moderate labelling of (125)I-UdR, whereas 40% of cells remain un-labelled. The dose-response relationship fits to a polynomial curve in the low dose range, whereas a linear fit supplies a better estimation in the high dose range. Even the lowest dose of 0.2Gy leads to a 13-fold increase of aberrations compared to the controls. On average every fifth (125)I-decay produces a single chromatid aberration in PBL. Additionally, a dose-dependent increase of cell death is observed. (125)I-UdR has a very strong genotoxic capacity in human PBL, even at 0.2Gy. Efficiently labelled cells displaying a prolonged cell cycle compared to moderately labelled cells and cell death contribute substantially to the desynchronisation of the cell cycle. Our data, showing for the first time, that one (125)I-decay induces ∼ 0.2 chromatid aberrations, are in very good accordance to DSB data, stating that ∼0.26 DSB are induced per decay, indicating that it takes on average 250 decays to induce one chromosome aberration (CA). [Corrected], (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: Identification of early radiation response genes (ERG) in human lymphocytes after gamma-irradiation by using the whole-human-genome DNA-microarrays and the evaluation of their possible role in rapid radiation biodosimetry by applying real-time quantitative polymerase chain reaction (RT-qPCR) methodology for validation in a small group of human individuals., Materials and Methods: Whole blood from a healthy human donor was exposed at 37 degrees C to 137Cs gamma-radiations (absorbed dose: 1-4 Gy). Fifteen minutes following irradiation the lymphocytes were isolated from the blood (for 2 h at 20 degrees C) and their gene expression was investigated using the DNA-microarrays. Subsequently, 14 genes were selected and validated using the TaqMan probes based upon the RT-qPCR assay within a group of 6 human donors., Results: A dose-related relative change in quantitative gene expression using the DNA-microarray assay was demonstrated in 24 of 102 genes. Up-regulation of expression was observed in 15 genes: CD69 (CD69 molecule), CDKN1A (cyclin-dependent kinase inhibitor 1A), EGR1 (early growth response 1), EGR4 (early growth response 4), FLJ35725 (chromosome 4 ORF 23), hCG2041177 (hCG - human Celera Genome), hCG1643466.2, IFN-gamma (interferon-gamma), ISG20L (interferon stimulated exonuclease gene 20 kDa - like 1), c-JUN (jun oncogene), MDM2 (mouse double minute 2), MUC5B (mucine), PLK2 (polo-like kinase 2), RND1 (rho-family GTPase 1) and TNFSF9 (tumour necrosis factor superfamily member 9). Down-regulation of expression was found in the remaining nine genes: GRIK3 (glutamate receptor ionotropic kainate 3), hCG1985174, hCG1998530, hCG2038519, OCLN (occludin), RPL10A (ribosomal protein L10a), SERHL2 (serine hydrolase-like 2), SGK3 (serum/glucocorticoid regulated kinase 3) and STARD13 (START domain containing 13)., Conclusion: A significant correlation between absorbed radiation dose and change in relative gene expression was particularly evident for EGR1, EGR4, IFN-gamma, c-JUN and TNFSF9 (p < or = 0.05). Results warrant the further investigation of these ERG as potential biodosimetric markers.