| 1. |
- Ainsbury, Elizabeth A., et al.
(författare)
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Inter- and intra-laboratory comparison of a multibiodosimetric approach to triage in a simulated, large scale radiation emergency
- 2014
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 90:2, s. 193-202
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: 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. Materials and methods: 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: <1 Gy; medium exposure: 1-2 Gy; high 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. Results: The results of the initial triage categorisation and the full comparison of assays and methods within and between laboratories are presented here. Conclusions: The data demonstrate that the MULTIBIODOSE approach of applying multiparametric tools to radiation emergencies is valid and effective.
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| 2. |
- Bajinskis, Ainars, et al.
(författare)
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DNA double strand breaks induced by the indirect effect of radiation are more efficiently repaired by non-homologous end joining compared to homologous recombination repair
- 2013
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Ingår i: Mutation research. Genetic toxicology and environmental mutagenesis. - : Elsevier BV. - 1383-5718 .- 1879-3592. ; 756:1-2, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the relative involvement of three major DNA repair pathways, i.e., non-homologous end joining (NHEJ), homologous recombination (HRR) and base excision (BER) in repair of DNA lesions of different complexity induced by low- or high-LET radiation with emphasis on the contribution of the indirect effect of radiation for these radiation qualities. A panel of DNA repair-deficient CHO cell lines was irradiated by Cs-137 gamma-rays or radon progeny alpha-particles. Irradiation was also performed in the presence of 2 M DMSO to reduce the indirect effect of radiation and the complexity of the DNA damage formed. Clonogenic survival and micronucleus assays were used to estimate efficiencies of the different repair pathways for DNA damages produced by direct and indirect effects. Removal of the indirect effect of low-LET radiation by DMSO increased clonogenic survival and decreased MN formation for all cell lines investigated. A direct contribution of the indirect effect of radiation to DNA base damage was suggested by the significant protection by DMSO seen for the BER deficient cell line. Lesions formed by the indirect effect are more readily repaired by the NHEJ pathway than by HRR after irradiation with gamma-rays or alpha-particles as evaluated by cell survival and the yields of MN. The results obtained with BER- and NHEJ-deficient cells suggest that the indirect effect of radiation contributes significantly to the formation of repair substrates for these pathways.
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| 3. |
- Bajinskis, Ainars, et al.
(författare)
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Low-Dose/Dose-Rate gamma Radiation Depresses Neural Differentiation and Alters Protein Expression Profiles in Neuroblastoma SH-SY5Y Cells and C17.2 Neural Stem Cells
- 2011
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Ingår i: Radiation Research. - 0033-7587 .- 1938-5404. ; 175:2, s. 185-192
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Tidskriftsartikel (refereegranskat)abstract
- The effects of low doses of ionizing radiation on cellular development in the nervous system are presently unclear. The focus of the present study was to examine low-dose gamma-radiation-induced effects on the differentiation of neuronal cells and on the development of neural stem cells to glial cells. Human neuroblastoma SH-SY5Y cells were exposed to (137)Cs gamma rays at different stages of retinoic acid-induced neuronal differentiation, and neurite formation was determined 6 days after exposure. When SH-SY5Y cells were exposed to low-dose-rate gamma rays at the onset of differentiation, the number of neurites formed per cell was significantly less after exposure to either 10, 30 or 100 mGy compared to control cells. Exposure to 10 and 30 mGy attenuated differentiation of immature C17.2 mouse-derived neural stem cells to glial cells, as verified by the diminished expression of glial fibrillary acidic protein. Proteomic analysis of the neuroblastoma cells by 2D-PAGE after 30 mGy irradiation showed that proteins involved in neuronal development were downregulated. Proteins involved in cell cycle and proliferation were altered in both cell lines after exposure to 30 mGy; however, the rate of cell proliferation was not affected in the low-dose range. The radiation-induced attenuation of differentiation and the persistent changes in protein expression is indicative of an epigenetic rather than a cytotoxic mechanism. (C) 2011 by Radiation Research Society
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| 4. |
- Bajinskis, Ainars, 1973-
(författare)
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Studies of DNA repair strategies in response to complex DNA damages
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main aim of this thesis was to study the role of the indirect actions of γ-rays and α-particles on the complexity of primary DNA damages and the repair fidelity of major DNA repair pathways: non-homologous end joining (NHEJ), homologous recombination repair (HRR) and base excision repair (BER). The complexity of radiation-induced damages increases and the proximity between damages decreases with increasing LET due to formation of ionization clusters along the particle track. The complexity of damages formed can be modified by the free radical scavenger dimethyl sulfoxide (DMSO). In addition, the effects of low doses of low dose rate γ-radiation on cellular response in terms of differentiation were investigated.Paper I investigates the role of the indirect effect of radiation on repair fidelity of HRR, NHEJ and BER when damages of different complexity were induced by radiation or by potassium bromate. We found that potassium bromate induces complex DNA damages through processing of base modifications and that the indirect effect of radiation has a high impact on the NHEJ pathway. Results in paper II confirmed our conclusions in paper I that the indirect effect from both γ-rays and α-particles has an impact on all three repair pathways studied and NHEJ benefits the most when the indirect effect of radiation is removed.In paper III we investigated the effects of low dose/dose rate γ-radiation on the developmental process of neural cells by using cell models for neurons and astrocytes. Our results suggest that low dose/dose rate γ-radiation attenuates differentiation and down-regulates proteins involved in the differentiation process of neural cells by an epigenetic rather than cytotoxic mechanism.
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| 5. |
- Bajinskis, Ainars, et al.
(författare)
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The indirect effect of radiation reduces the repair fidelity of NHEJ as verified in repair deficient CHO cell lines exposed to different radiation qualities and potassium bromate
- 2012
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Ingår i: Mutation research. - : Elsevier. - 0027-5107 .- 1873-135X. ; 731, s. 125-132
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Tidskriftsartikel (refereegranskat)abstract
- The complexity of DNA lesions induced by ionizing radiation is mainly dependent on radiation quality, where the indirect action of radiation may contribute to different extent depending on the type of radiation under study. The effect of indirect action of radiation can be investigated by using agents that induce oxidative DNA damage or by applying free radical scavengers. The aim of this study was to investigate the role of the indirect effect of radiation for the repair fidelity of non-homologous end-joining (NHEJ), homologous recombination repair (HRR) and base excision repair (BER) when DNA damage of different complexity was induced by gamma radiation, alpha particles or from base damages (8-oxo-dG) induced by potassium bromate (KBrO3).CHO cells lines deficient in XRCC3 (HRR) irs1SF, XRCC7 (NHEJ) V3-3 and XRCC1 (BER) EM9 were irradiated in the absence or presence of the free radical scavenger dimethyl sulphoxide (DMSO). The endpoints investigated included rate of cell proliferation by the DRAG assay, clonogenic cell survival and the level of primary DNA damage by the comet assay.The results revealed that the indirect effect of low-LET radiation significantly reduced the repair fidelity of both NHEJ and HRR pathways. For high-LET radiation the indirect effect of radiation also significantly reduced the repair fidelity for the repair deficient cell lines. The results suggest further that the repair fidelity of the error prone NHEJ repair pathway is more impaired by the indirect effect of high-LET radiation relative to the other repair pathways studied. The response to bromate observed for the two DSB repair deficient cell lines strongly support earlier studies that bromate induces complex DNA damages. The significantly reduced repair fidelity of irs1SF and V3-3 suggests that NHEJ as well as HRR are needed for the repair, and that complex DSBs are formed after bromate exposure.
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| 6. |
- Bajinskis, Ainars, et al.
(författare)
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The response of HRR-deficient Chinese hamster ovary cell line reveals significant contribution of the indirect effect from both γ-rays and α-particles on NHEJ pathway
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In order to investigate the relative involvement of the different DNA repair pathways NHEJ, HRR and BER in repair of DNA lesions of different complexity, we have compared clonogenic survival and induction of micronuclei in a panel of repair-deficient CHO cell lines after exposure to γ-rays and α-particle radiation. The complexity of the DNA lesions formed was also modified by exposures to2 MDMSO, a potent radical scavenger, which is known to interact with the lesions produced by direct hits on DNA.The NHEJ pathway gained the most from scavenging of the free radicals after irradiation to γ-rays or α-particles as evaluated by cell survival and the yields of MN. Results presented here also implicate that clustered base damages were induced by α-radiation and contributed to the yield of DNA double-strand breaks.
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| 7. |
- Bajinskis, Ainars, et al.
(författare)
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The response of HRR-deficient Chinese hamster ovary cell line reveals significant contribution of the indirect effect from both γ-rays and α-particles on NHEJ pathway
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In order to investigate the relative involvement of the different DNA repair pathways NHEJ, HRR and BER in repair of DNA lesions of different complexity, we have compared clonogenic survival and induction of micronuclei in a panel of repair-deficient CHO cell lines after exposure to γ-rays and α-particle radiation. The complexity of the DNA lesions formed was also modified by exposures to 2 M DMSO, a potent radical scavenger, which is known to interact with the lesions produced by direct hits on DNA.The NHEJ pathway gained the most from scavenging of the free radicals after irradiation to γ-rays or α-particles as evaluated by cell survival and the yields of MN. Results presented here also implicate that clustered base damages were induced by α-radiation and contributed to the yield of DNA double-strand breaks.
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| 8. |
- Brehwens, Karl, et al.
(författare)
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A new device to expose cells to changing dose rates of ionising radiation
- 2012
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 148:3, s. 366-371
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Tidskriftsartikel (refereegranskat)abstract
- In many exposure scenarios to ionising radiation, the dose rate is not constant. Despite this, most in vitro studies aimed at investigating the effects of ionising radiation are carried out exposing samples at constant dose rates. Consequently, very little data exist on the biological effects of exposures to changing dose rates. This may be due to technical limitations of standard irradiation facilities, but also to the fact that the importance of research in this area has not been appreciated. We have recently shown that cells exposed to a decreasing dose rate suffer higher levels of cytogenetic damage than do cells exposed to an increasing or a constant dose rate. To further study the effects of changing dose rates, a new device was constructed that permits the exposure of cell samples in tubes, flasks or Petri dishes to changing dose rates of X-rays. This report presents the technical data, performance and dosimetry of this novel device.
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| 9. |
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| 10. |
- Brehwens, Karl, 1983-, et al.
(författare)
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Micronucleus frequencies and clonogenic cell survival in TK6 cells exposed to changing dose rates under controlled temperature conditions
- 2014
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Ingår i: International Journal of Radiation Biology. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 90:3, s. 241-247
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: In most exposure scenarios the dose rate of exposure is not constant. Despite this, very little information exists on the possible biological effects of exposing cells to radiation under the conditions of a changing dose rate. The current study highlights interesting effects following exposure under these conditions.Materials and methods: We constructed a new exposure facility that allows exposing cells inside an incubator and used it to irradiate human lymphoblastoid TK6 cells both after a moderate (0.48 Gy) and a high (1.1 Gy) dose, where the change in dose rate was, respectively, ≈ 17-fold change (2.2 - 37 mGy/min) and ≈ 39-fold (2.7 - 106 mGy/min). Clonogenic survival and micronuclei (MN) induction were the chosen endpoints.Results: The obtained results confirm the outcome of our first study that TK6 cells exposed to a decreasing dose rate express more MN than cells exposed to an increasing or constant dose rate. The effect was not seen after the moderate dose of 0.48 Gy or detectable at the level of clonogenic cell survival.Conclusions: We speculate that the high level of MN is probably related to a delayed elimination of damaged cells by interphase death, as opposed to mechanisms relating to DNA damage and repair.
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| 11. |
- Deperas-Kaminska, Marta, et al.
(författare)
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RADIATION-INDUCED CHANGES IN LEVELS OF SELECTED PROTEINS IN PERIPHERAL BLOOD SERUM OF BREAST CANCER PATIENTS AS A POTENTIAL TRIAGE BIODOSIMETER FOR LARGE-SCALE RADIOLOGICAL EMERGENCIES
- 2014
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Ingår i: Health Physics. - 0017-9078 .- 1538-5159. ; 107:6, s. 555-563
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Tidskriftsartikel (refereegranskat)abstract
- The threat of a large scale radiological emergency, where thousands of people may require fast biological dosimetry for the purpose of triage, makes it necessary to search for new, high throughput biological dosimeters. The authors tested an assay based on the quantitative analysis of selected proteins in peripheral blood serum. They were particularly interested in testing proteins that are specific to irradiation of skin, as these can be used in cases of partial body exposure. Candidate proteins were identified in an earlier study with mice, where skin of the animals was exposed to different doses of radiation and global expression of serum proteins was analyzed. Eight proteins were found, the expression of which showed a consistent dose-response relationship. Human analogues of these proteins were identified, and their expression was measured in peripheral blood serum of 16 breast cancer patients undergoing external beam radiotherapy. The proteins were Apolipoprotein E; Apolipoprotein H; Complement protein 7; Prothrombinase; Pantothenate Kinase 4; Alpha-2-macroglobulin; Fetuin B and Alpha-1-Anti-Chymotrypsin. Measurements were carried out in blood samples collected prior to exposure (control), on the day after one fraction (2 Gy), on the day after five fractions (10 Gy), on the day after 10 fractions (20 Gy), and 1 mo after 23-25 fractions (total dose of 46-50 Gy). Multivariate analysis was carried out, and a multinomial logistic regression model was built. The results indicate that the combined analysis of Apolipoprotein E, Factor X, and Pantothenate Kinase 4 allows discriminating between exposure to 2 Gy and lower and between 10 Gy and higher. The discrimination is possible up to 1 mo after exposure.
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| 12. |
- Romm, H., et al.
(författare)
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Web-based scoring of the dicentric assay, a collaborative biodosimetric scoring strategy for population triage in large scale radiation accidents
- 2014
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Ingår i: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 0301-634X .- 1432-2099. ; 53:2, s. 241-254
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Tidskriftsartikel (refereegranskat)abstract
- In the case of a large scale radiation accident high throughput methods of biological dosimetry for population triage are needed to identify individuals requiring clinical treatment. The dicentric assay performed in web-based scoring mode may be a very suitable technique. Within the MULTIBIODOSE EU FP7 project a network is being established of 8 laboratories with expertise in dose estimations based on the dicentric assay. Here, the manual dicentric assay was tested in a web-based scoring mode. More than 23,000 high resolution images of metaphase spreads (only first mitosis) were captured by four laboratories and established as image galleries on the internet (cloud). The galleries included images of a complete dose effect curve (0-5.0 Gy) and three types of irradiation scenarios simulating acute whole body, partial body and protracted exposure. The blood samples had been irradiated in vitro with gamma rays at the University of Ghent, Belgium. Two laboratories provided image galleries from Fluorescence plus Giemsa stained slides (3 h colcemid) and the image galleries from the other two laboratories contained images from Giemsa stained preparations (24 h colcemid). Each of the 8 participating laboratories analysed 3 dose points of the dose effect curve (scoring 100 cells for each point) and 3 unknown dose points (50 cells) for each of the 3 simulated irradiation scenarios. At first all analyses were performed in a QuickScan Mode without scoring individual chromosomes, followed by conventional scoring (only complete cells, 46 centromeres). The calibration curves obtained using these two scoring methods were very similar, with no significant difference in the linear-quadratic curve coefficients. Analysis of variance showed a significant effect of dose on the yield of dicentrics, but no significant effect of the laboratories, different methods of slide preparation or different incubation times used for colcemid. The results obtained to date within the MULTIBIODOSE project by a network of 8 collaborating laboratories throughout Europe are very promising. The dicentric assay in the web based scoring mode as a high throughput scoring strategy is a useful application for biodosimetry in the case of a large scale radiation accident.
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