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Averbeck D. Low-Dose Non-Targeted Effects and Mitochondrial Control. Int J Mol Sci 2023; 24:11460. [PMID: 37511215 PMCID: PMC10380638 DOI: 10.3390/ijms241411460] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/26/2023] [Accepted: 06/29/2023] [Indexed: 07/30/2023] Open
Abstract
Non-targeted effects (NTE) have been generally regarded as a low-dose ionizing radiation (IR) phenomenon. Recently, regarding long distant abscopal effects have also been observed at high doses of IR) relevant to antitumor radiation therapy. IR is inducing NTE involving intracellular and extracellular signaling, which may lead to short-ranging bystander effects and distant long-ranging extracellular signaling abscopal effects. Internal and "spontaneous" cellular stress is mostly due to metabolic oxidative stress involving mitochondrial energy production (ATP) through oxidative phosphorylation and/or anaerobic pathways accompanied by the leakage of O2- and other radicals from mitochondria during normal or increased cellular energy requirements or to mitochondrial dysfunction. Among external stressors, ionizing radiation (IR) has been shown to very rapidly perturb mitochondrial functions, leading to increased energy supply demands and to ROS/NOS production. Depending on the dose, this affects all types of cell constituents, including DNA, RNA, amino acids, proteins, and membranes, perturbing normal inner cell organization and function, and forcing cells to reorganize the intracellular metabolism and the network of organelles. The reorganization implies intracellular cytoplasmic-nuclear shuttling of important proteins, activation of autophagy, and mitophagy, as well as induction of cell cycle arrest, DNA repair, apoptosis, and senescence. It also includes reprogramming of mitochondrial metabolism as well as genetic and epigenetic control of the expression of genes and proteins in order to ensure cell and tissue survival. At low doses of IR, directly irradiated cells may already exert non-targeted effects (NTE) involving the release of molecular mediators, such as radicals, cytokines, DNA fragments, small RNAs, and proteins (sometimes in the form of extracellular vehicles or exosomes), which can induce damage of unirradiated neighboring bystander or distant (abscopal) cells as well as immune responses. Such non-targeted effects (NTE) are contributing to low-dose phenomena, such as hormesis, adaptive responses, low-dose hypersensitivity, and genomic instability, and they are also promoting suppression and/or activation of immune cells. All of these are parts of the main defense systems of cells and tissues, including IR-induced innate and adaptive immune responses. The present review is focused on the prominent role of mitochondria in these processes, which are determinants of cell survival and anti-tumor RT.
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Affiliation(s)
- Dietrich Averbeck
- Laboratory of Cellular and Molecular Radiobiology, PRISME, UMR CNRS 5822/IN2P3, IP2I, Lyon-Sud Medical School, University Lyon 1, 69921 Oullins, France
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Cherif J, Raddaoui A, Trabelsi M, Souissi N. Diagnostic low-dose X-ray radiation induces fluoroquinolone resistance in pathogenic bacteria. Int J Radiat Biol 2023; 99:1971-1977. [PMID: 37436698 DOI: 10.1080/09553002.2023.2232016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 06/27/2023] [Indexed: 07/13/2023]
Abstract
PURPOSE The crisis of antibiotic resistance has been attributed to the overuse or misuse of these medications. However, exposure of bacteria to physical stresses such as X-ray radiation, can also lead to the development of resistance to antibiotics. The present study aimed to investigate the effect of exposure to diagnostic low-dose X-ray radiation on the bacterial response to antibiotics in two pathogenic bacteria, including the Gram-positive Staphylococcus aureus and Gram-negative Salmonella enteritidis. METHODS The bacterial strains were exposed to diagnostic X-ray doses of 5 and 10 mGy, which are equivalent to the doses delivered to patients during conventional radiography X-ray examinations in accordance with the European guidelines on quality criteria for diagnostic radiographic images. Following exposure to X-ray radiation, the samples were used to estimate bacterial growth dynamics and perform antibiotic susceptibility tests. RESULTS The results indicate that exposure to diagnostic low-dose X-ray radiation increased the number of viable bacterial colonies of both Staphylococcus aureus and Salmonella enteritidis and caused a significant change in bacterial susceptibility to antibiotics. For instance, in Staphylococcus aureus, the diameter of the inhibition zones for marbofloxacin decreased from 29.66 mm before irradiation to 7 mm after irradiation. A significant decrease in the inhibition zone was also observed for penicillin. In the case of Salmonella enteritidis, the diameter of the inhibition zone for marbofloxacin was 29 mm in unexposed bacteria but decreased to 15.66 mm after exposure to 10 mGy of X-ray radiation. Furthermore, a significant decrease in the inhibition zone was detected for amoxicillin and amoxicillin/clavulanic acid (AMC). CONCLUSION It is concluded that exposure to diagnostic X-ray radiation can significantly alter bacterial susceptibility to antibiotics. This irradiation decreased the effectiveness of fluoroquinolone and β-lactam antibiotics. Specifically, low-dose X-rays made Staphylococcus aureus resistant to marbofloxacin and increased its resistance to penicillin. Similarly, Salmonella Enteritidis became resistant to both marbofloxacin and enrofloxacin, and showed reduced sensitivity to amoxicillin and AMC.
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Affiliation(s)
- Jaouhra Cherif
- Laboratory of Biophysics and Medical Technologies, Higher Institute of Medical Technologies of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Anis Raddaoui
- Laboratory Ward, National Bone Marrow Transplant Center, University of Tunis El Manar, Tunis, Tunisia
| | - Meriam Trabelsi
- Higher Institute of Medical Technologies of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Nada Souissi
- Bacteriology Laboratory, Tunisian Institute of Veterinary Research, University of Tunis El Manar, Tunis, Tunisia
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Fornalski KW, Adamowski Ł, Dobrzyński L, Jarmakiewicz R, Powojska A, Reszczyńska J. The radiation adaptive response and priming dose influence: the quantification of the Raper-Yonezawa effect and its three-parameter model for postradiation DNA lesions and mutations. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2022; 61:221-239. [PMID: 35150289 PMCID: PMC9021059 DOI: 10.1007/s00411-022-00963-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 01/12/2022] [Indexed: 05/14/2023]
Abstract
The priming dose effect, called also the Raper-Yonezawa effect or simply the Yonezawa effect, is a special case of the radiation adaptive response phenomenon (radioadaptation), which refers to: (a) faster repair of direct DNA lesions (damage), and (b) DNA mutation frequency reduction after irradiation, by applying a small priming (conditioning) dose prior to the high detrimental (challenging) one. This effect is observed in many (but not all) radiobiological experiments which present the reduction of lesion, mutation or even mortality frequency of the irradiated cells or species. Additionally, the multi-parameter model created by Dr. Yonezawa and collaborators tried to explain it theoretically based on experimental data on the mortality of mice with chronic internal irradiation. The presented paper proposes a new theoretical approach to understanding and explaining the priming dose effect: it starts from the radiation adaptive response theory and moves to the three-parameter model, separately for two previously mentioned situations: creation of fast (lesions) and delayed damage (mutations). The proposed biophysical model was applied to experimental data-lesions in human lymphocytes and chromosomal inversions in mice-and was shown to be able to predict the Yonezawa effect for future investigations. It was also found that the strongest radioadaptation is correlated with the weakest cellular radiosensitivity. Additional discussions were focussed on more general situations where many small priming doses are used.
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Affiliation(s)
- Krzysztof W Fornalski
- National Centre for Nuclear Research (NCBJ), ul. A. Sołtana 7, 05-400, Otwock-Świerk, Poland.
| | - Łukasz Adamowski
- National Centre for Nuclear Research (NCBJ), ul. A. Sołtana 7, 05-400, Otwock-Świerk, Poland
| | - Ludwik Dobrzyński
- National Centre for Nuclear Research (NCBJ), ul. A. Sołtana 7, 05-400, Otwock-Świerk, Poland
| | - Rafał Jarmakiewicz
- Faculty of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662, Warsaw, Poland
| | - Aleksandra Powojska
- Faculty of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662, Warsaw, Poland
| | - Joanna Reszczyńska
- Department of Biophysics, Physiology and Pathophysiology, Faculty of Health Sciences, Medical University of Warsaw (WUM), ul. T. Chałubińskiego 5, 02-004, Warsaw, Poland
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Bannister L, Serran M, Bertrand L, Klokov D, Wyatt H, Blimkie M, Gueguen Y, Priest N, Jourdain JR, Sykes P. Environmentally Relevant Chronic Low-Dose Tritium and Gamma Exposures do not Increase Somatic Intrachromosomal Recombination in pKZ1 Mouse Spleen. Radiat Res 2016; 186:539-548. [PMID: 27922333 DOI: 10.1667/rr14564.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The toxicity of tritium is a public health concern given its presence and mobility in the environment. For risk predictions using radiological protection models, it is essential to allocate an appropriate radiation weighting factor (WR). This in turn should be consistent with the observed relative biological effectiveness (RBE) of tritium beta radiation. Although the International Commission on Radiological Protection (ICRP) currently recommends a WR of 1 for the calculation of committed effective dose for X rays, gamma rays and electrons of all energies, including tritium energies, there are concerns that tritium health risks are underestimated and that current regulatory tritium drinking water standards need revision. In this study, we investigated potential cytotoxic and genotoxic effects in mouse spleen after one month and eight months of chronic exposure to low-dose tritiated water (HTO). The dose regimes studied were designed to mimic human chronic consumption of HTO at levels of 10 kBq/l, 1 MBq/l and 20 MBq/l. The total doses from these radiation exposures ranged from 0.01 to 180 mGy. We also compared the biological effects of exposure to HTO with equivalent exposure to external whole-body 60Co gamma rays. Changes in spleen weight and somatic intrachromosomal recombination (DNA inversions) in spleen tissue of pKZ1Tg/+ mice were monitored. Our results showed no overall changes in either spleen organ weights and no increase mouse splenic intrachromosomal recombination frequencies, indicating that current drinking water standards for tritium exposure in the form of HTO are likely to be adequately protective against cytotoxic and genotoxic damage in spleen. These results demonstrate no evidence for cytotoxicity or genotoxicity in mouse spleen following chronic exposures to HTO activities (or equivalent gamma doses) up to 20 MBq/L.
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Affiliation(s)
- Laura Bannister
- a Canadian Nuclear Laboratories, Chalk River, Ontario, Canada
| | - Mandy Serran
- a Canadian Nuclear Laboratories, Chalk River, Ontario, Canada
| | | | - Dmitry Klokov
- a Canadian Nuclear Laboratories, Chalk River, Ontario, Canada
| | - Heather Wyatt
- a Canadian Nuclear Laboratories, Chalk River, Ontario, Canada
| | - Melinda Blimkie
- a Canadian Nuclear Laboratories, Chalk River, Ontario, Canada
| | - Yann Gueguen
- b Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM, Fontenay-aux-Roses, France
| | - Nicholas Priest
- a Canadian Nuclear Laboratories, Chalk River, Ontario, Canada
| | - Jean-René Jourdain
- b Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-HOM, Fontenay-aux-Roses, France
| | - Pamela Sykes
- c Flinders Centre for Innovation in Cancer, Flinders University of South Australia, SA, Australia
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Ormsby RJ, Staudacher AH, Blyth BJ, Bezak E, Sykes PJ. Temporal Responses to X-Radiation Exposure in Spleen in the pKZ1 Mouse Recombination Assay. Radiat Res 2016; 185:623-9. [PMID: 27223829 DOI: 10.1667/rr14390.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The in vivo mouse transgenic pKZ1 chromosomal inversion assay is a sensitive assay that responds to very low doses of DNA-damaging agents. pKZ1 inversions are measured as the frequency of cells expressing E. coli β-galactosidase protein, which can only be produced from an inverted pKZ1 transgene. In previous studies we reported that a single whole-body low dose of 0.01 mGy X rays alone caused an increase in pKZ1 chromosomal inversions in spleen when analyzed 3 days postirradiation, and yet this same dose could protect from high-dose-induced inversions when delivered as a conditioning dose 4 h before or after a 1 Gy challenge dose. In an attempt to explain these results, we performed temporal studies over a wide radiation dose range to determine if the inversion response was temporally different at different doses. pKZ1 mice were irradiated with a single whole-body X-ray dose of 0.01 mGy, 1 mGy or 1 Gy, and spleen sections were then analyzed for pKZ1 inversions at 7 h, 1 day or 7 days after exposure. No change in inversion frequency was observed at the 7 h time point at any dose. At day 1, an increase in inversions was observed in response to the 0.01 mGy dose, whereas a decrease in inversions below sham-treated frequency was observed for the 1 mGy dose. Inversion frequency for both doses returned to sham-treated inversion frequency by day 7. To our knowledge, this is the first reported study to examine the temporal nature of a radiation response spanning a wide dose range, including doses relevant to occupational exposure, and the results are dynamic and dose specific. The results suggest that inversions induced after low-dose irradiation are removed by homeostatic mechanisms within a short time frame, and underscore the importance of studying responses over a period of time when interpreting radiation effects.
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Affiliation(s)
- Rebecca J Ormsby
- a Flinders Centre for Innovation in Cancer, Flinders University, Bedford Park, South Australia
| | - Alexander H Staudacher
- a Flinders Centre for Innovation in Cancer, Flinders University, Bedford Park, South Australia
| | - Benjamin J Blyth
- a Flinders Centre for Innovation in Cancer, Flinders University, Bedford Park, South Australia
| | - Eva Bezak
- b International Centre for Allied Health Evidence and Sansom Institute for Health Research, University of South Australia, Adelaide, Australia; and.,c School of Physical Sciences, University of Adelaide, Adelaide, Australia
| | - Pamela J Sykes
- a Flinders Centre for Innovation in Cancer, Flinders University, Bedford Park, South Australia
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Rogers LJ, Suchowerska N, Ralston A, Napper A, McKenzie DR. Imaging dose affects
in vitro
survival following subsequent therapeutic irradiation. Biomed Phys Eng Express 2015. [DOI: 10.1088/2057-1976/1/4/045016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Harvey HB, Brink JA, Frush DP. Informed Consent for Radiation Risk from CT Is Unjustified Based on the Current Scientific Evidence. Radiology 2015; 275:321-5. [PMID: 25906299 DOI: 10.1148/radiol.2015142859] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- H Benjamin Harvey
- From the Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 175 Cambridge St, Suite 200, Boston, MA 02114 (H.B.H., J.A.B.); and Department of Radiology, Duke University Medical Center, Durham, NC (D.P.F.)
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Newman MR, Sykes PJ, Blyth BJ, Bezak E, Lawrence MD, Morel KL, Ormsby RJ. A single whole-body low dose X-irradiation does not affect L1, B1 and IAP repeat element DNA methylation longitudinally. PLoS One 2014; 9:e93016. [PMID: 24676381 PMCID: PMC3968115 DOI: 10.1371/journal.pone.0093016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 02/27/2014] [Indexed: 11/18/2022] Open
Abstract
The low dose radioadaptive response has been shown to be protective against high doses of radiation as well as aging-induced genomic instability. We hypothesised that a single whole-body exposure of low dose radiation would induce a radioadaptive response thereby reducing or abrogating aging-related changes in repeat element DNA methylation in mice. Following sham or 10 mGy X-irradiation, serial peripheral blood sampling was performed and differences in Long Interspersed Nucleic Element 1 (L1), B1 and Intracisternal-A-Particle (IAP) repeat element methylation between samples were assessed using high resolution melt analysis of PCR amplicons. By 420 days post-irradiation, neither radiation- or aging-related changes in the methylation of peripheral blood, spleen or liver L1, B1 and IAP elements were observed. Analysis of the spleen and liver tissues of cohorts of untreated aging mice showed that the 17-19 month age group exhibited higher repeat element methylation than younger or older mice, with no overall decline in methylation detected with age. This is the first temporal analysis of the effect of low dose radiation on repeat element methylation in mouse peripheral blood and the first to examine the long term effect of this dose on repeat element methylation in a radiosensitive tissue (spleen) and a tissue fundamental to the aging process (liver). Our data indicate that the methylation of murine DNA repeat elements can fluctuate with age, but unlike human studies, do not demonstrate an overall aging-related decline. Furthermore, our results indicate that a low dose of ionising radiation does not induce detectable changes to murine repeat element DNA methylation in the tissues and at the time-points examined in this study. This radiation dose is relevant to human diagnostic radiation exposures and suggests that a dose of 10 mGy X-rays, unlike high dose radiation, does not cause significant short or long term changes to repeat element or global DNA methylation.
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Affiliation(s)
- Michelle R. Newman
- Flinders Centre for Innovation in Cancer, Flinders University and Medical Centre, Bedford Park, South Australia, Australia
| | - Pamela J. Sykes
- Flinders Centre for Innovation in Cancer, Flinders University and Medical Centre, Bedford Park, South Australia, Australia
| | - Benjamin J. Blyth
- Flinders Centre for Innovation in Cancer, Flinders University and Medical Centre, Bedford Park, South Australia, Australia
| | - Eva Bezak
- Department of Medical Physics, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Mark D. Lawrence
- Flinders Centre for Innovation in Cancer, Flinders University and Medical Centre, Bedford Park, South Australia, Australia
| | - Katherine L. Morel
- Flinders Centre for Innovation in Cancer, Flinders University and Medical Centre, Bedford Park, South Australia, Australia
| | - Rebecca J. Ormsby
- Flinders Centre for Innovation in Cancer, Flinders University and Medical Centre, Bedford Park, South Australia, Australia
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Yu HS, Liu ZM, Yu XY, Song AQ, Liu N, Wang H. Low-dose radiation induces antitumor effects and erythrocyte system hormesis. Asian Pac J Cancer Prev 2014; 14:4121-6. [PMID: 23991963 DOI: 10.7314/apjcp.2013.14.7.4121] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Low dose radiation may stimulate the growth and development of animals, increase life span, enhance fertility, and downgrade the incidence of tumor occurrence.The aim of this study was to investigate the antitumor effect and hormesis in an erythrocyte system induced by low-dose radiation. METHODS Kunming strain male mice were subcutaneously implanted with S180 sarcoma cells in the right inguen as an experimental in situ animal model. Six hours before implantation, the mice were given 75mGy whole body X-ray radiation. Tumor growth was observed 5 days later, and the tumor volume was calculated every other day. Fifteen days later, all mice were killed to measure the tumor weight, and to observe necrotic areas and tumor-infiltration-lymphoreticular cells (TILs). At the same time, erythrocyte immune function and the level of 2,3-diphosphoglyceric acid (2,3- DPG) were determined. Immunohistochemical staining was used to detect the expression of EPO and VEGFR of tumor tissues. RESULTS The mice pre-exposed to low dose radiation had a lower tumor formation rate than those without low dose radiation (P < 0.05). The tumor growth slowed down significantly in mice pre-exposed to low dose radiation; the average tumor weight in mice pre-exposed to low dose radiation was lighter too (P < 0.05). The tumor necrosis areas were larger and TILs were more in the radiation group than those of the group without radiation. The erythrocyte immune function, the level of 2,3-DPG in the low dose radiation group were higher than those of the group without radiation (P < 0.05). After irradiation the expression of EPO of tumor tissues in LDR group decreased with time. LDR-24h, LDR-48h and LDR-72h groups were all statistically significantly different from sham-irradiation group. The expression of VEGFR also decreased, and LDR-24h group was the lowest (P < 0.05). CONCLUSION Low dose radiation could markedly increase the anti-tumor ability of the organism and improve the erythrocyte immune function and the ability of carrying O2. Low-dose total body irradiation, within a certain period of time, can decrease the expression of hypoxia factor EPO and VEGFR, which may improve the situation of tumor hypoxia and radiosensitivity of tumor itself.
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Affiliation(s)
- Hong-Sheng Yu
- Department of Oncology, the Affiliated Hospital of Medical College, Qingdao University, Qingdao, China.
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10
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Abstract
The atomic bomb survivor cancer mortality data have been used in the past to justify the use of the linear no-threshold (LNT) model for estimating the carcinogenic effects of low dose radiation. An analysis of the recently updated atomic bomb survivor cancer mortality dose-response data shows that the data no longer support the LNT model but are consistent with a radiation hormesis model when a correction is applied for a likely bias in the baseline cancer mortality rate. If the validity of the phenomenon of radiation hormesis is confirmed in prospective human pilot studies, and is applied to the wider population, it could result in a considerable reduction in cancers. The idea of using radiation hormesis to prevent cancers was proposed more than three decades ago, but was never investigated in humans to determine its validity because of the dominance of the LNT model and the consequent carcinogenic concerns regarding low dose radiation. Since cancer continues to be a major health problem and the age-adjusted cancer mortality rates have declined by only ∼10% in the past 45 years, it may be prudent to investigate radiation hormesis as an alternative approach to reduce cancers. Prompt action is urged.
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Zhang K, Han J, Groesser T, Fontenay G, Parvin B. Inference of causal networks from time-varying transcriptome data via sparse coding. PLoS One 2012; 7:e42306. [PMID: 22916126 PMCID: PMC3423420 DOI: 10.1371/journal.pone.0042306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 07/06/2012] [Indexed: 11/19/2022] Open
Abstract
Temporal analysis of genome-wide data can provide insights into the underlying mechanism of the biological processes in two ways. First, grouping the temporal data provides a richer, more robust representation of the underlying processes that are co-regulated. The net result is a significant dimensional reduction of the genome-wide array data into a smaller set of vocabularies for bioinformatics analysis. Second, the computed set of time-course vocabularies can be interrogated for a potential causal network that can shed light on the underlying interactions. The method is coupled with an experiment for investigating responses to high doses of ionizing radiation with and without a small priming dose. From a computational perspective, inference of a causal network can rapidly become computationally intractable with the increasing number of variables. Additionally, from a bioinformatics perspective, larger networks always hinder interpretation. Therefore, our method focuses on inferring the simplest network that is computationally tractable and interpretable. The method first reduces the number of temporal variables through consensus clustering to reveal a small set of temporal templates. It then enforces simplicity in the network configuration through the sparsity constraint, which is further regularized by requiring continuity between consecutive time points. We present intermediate results for each computational step, and apply our method to a time-course transcriptome dataset for a cell line receiving a challenge dose of ionizing radiation with and without a prior priming dose. Our analyses indicate that (i) the priming dose increases the diversity of the computed templates (e.g., diversity of transcriptome signatures); thus, increasing the network complexity; (ii) as a result of the priming dose, there are a number of unique templates with delayed and oscillatory profiles; and (iii) radiation-induced stress responses are enriched through pathway and subnetwork studies.
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Affiliation(s)
| | | | | | | | - Bahram Parvin
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- * E-mail:
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Abstract
In 2005, two expert advisory bodies examined the evidence on the effects of low doses of ionizing radiation. The U.S. National Research Council concluded that current scientific evidence is consistent with the linear no-threshold dose-response relationship (NRCNA 2005) while the French National Academies of Science and Medicine concluded the opposite (Aurengo et al. 2005). These contradictory conclusions may stem in part from an emphasis on epidemiological data (a "top down" approach) versus an emphasis on biological mechanisms (a "bottom up" approach). In this paper, the strengths and limitations of the top down and bottom up approaches are discussed, and proposals for strengthening and reconciling them are suggested. The past seven years since these two reports were published have yielded increasing evidence of nonlinear responses of biological systems to low radiation doses delivered at low dose-rates. This growing body of evidence is casting ever more doubt on the extrapolation of risks observed at high doses and dose-rates to estimate risks associated with typical environmental and occupational exposures. This paper compares current evidence on low dose, low dose-rate effects against objective criteria of causation. Finally, some questions for a post-LNT world are posed.
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Zuo B, Du X, Zhao J, Yang H, Wang C, Wu Y, Lu J, Wang Y, Chen Z. Analysis of microsatellite polymorphism in inbred knockout mice. PLoS One 2012; 7:e34555. [PMID: 22509320 PMCID: PMC3324499 DOI: 10.1371/journal.pone.0034555] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 03/02/2012] [Indexed: 02/07/2023] Open
Abstract
Previously, we found that the genotype of 42 out of 198 mouse microsatellite loci, which are distributed among all chromosomes except the Y chromosome, changed from monomorphism to polymorphism (CMP) in a genetically modified inbred mouse strain. In this study, we further examined whether CMP also relates to the homologous recombination in gene knockout (KO) mouse strains. The same 42 microsatellite loci were analyzed by polymerase chain reaction (PCR) in 29 KO inbred mouse strains via short tandem sequence repeat (STR) scanning and direct sequence cloning to justify microsatellite polymorphisms. The C57BL/6J and 129 mouse strains, from which these 29 KO mice were derived, were chosen as the background controls. The results indicated that 10 out of 42 (23.8%) loci showed CMP in some of these mouse strains. Except for the trinucleotide repeat locus of D3Mit22, which had microsatellite CMP in strain number 9, the core sequences of the remaining 41 loci were dinucleotide repeats, and 9 out of 41 (21.95%) showed CMPs among detected mouse strains. However, 11 out of 29 (37.9%) KO mice strains were recognized as having CMPs. The popular dinucleotide motifs in CMP were (TG)n (50%, 2/4), followed by (GT)n (27.27%, 3/11) and (CA)n (23.08%, 3/13). The microsatellite CMP in (CT)n and (AG)n repeats were 20% (1/5). According to cloning sequencing results, 6 KO mouse strains showed insertions of nucleotides whereas 1 showed a deletion. Furthermore, 2 loci (D13Mit3 and D14Mit102) revealed CMP in 2 strains, and mouse strain number 9 showed CMPs in two loci (D3Mit22 and D13Mit3) simultaneously. Collectively, these results indicated that microsatellite polymorphisms were present in the examined inbred KO mice.
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Affiliation(s)
- Baofen Zuo
- Department of Laboratory Animal Science, School of Basic Medical Science, Capital Medical University, Beijing, China
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Blyth BJ, Sykes PJ. Radiation-induced bystander effects: what are they, and how relevant are they to human radiation exposures? Radiat Res 2011; 176:139-57. [PMID: 21631286 DOI: 10.1667/rr2548.1] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The term radiation-induced bystander effect is used to describe radiation-induced biological changes that manifest in unirradiated cells remaining within an irradiated cell population. Despite their failure to fit into the framework of classical radiobiology, radiation-induced bystander effects have entered the mainstream and have become established in the radiobiology vocabulary as a bona fide radiation response. However, there is still no consensus on a precise definition of radiation-induced bystander effects, which currently encompasses a number of distinct signal-mediated effects. These effects are classified here into three classes: bystander effects, abscopal effects and cohort effects. In this review, the data have been evaluated to define, where possible, various features specific to radiation-induced bystander effects, including their timing, range, potency and dependence on dose, dose rate, radiation quality and cell type. The weight of evidence supporting these defining features is discussed in the context of bystander experimental systems that closely replicate realistic human exposure scenarios. Whether the manifestation of bystander effects in vivo is intrinsically limited to particular radiation exposure scenarios is considered. The conditions under which radiation-induced bystander effects are induced in vivo will ultimately determine their impact on radiation-induced carcinogenic risk.
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Affiliation(s)
- Benjamin J Blyth
- Haematology and Genetic Pathology, Flinders University, Bedford Park, South Australia 5042, Australia
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Ulsh BA. Checking the foundation: recent radiobiology and the linear no-threshold theory. HEALTH PHYSICS 2010; 99:747-758. [PMID: 21068593 DOI: 10.1097/hp.0b013e3181e32477] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The linear no-threshold (LNT) theory has been adopted as the foundation of radiation protection standards and risk estimation for several decades. The "microdosimetric argument" has been offered in support of the LNT theory. This argument postulates that energy is deposited in critical cellular targets by radiation in a linear fashion across all doses down to zero, and that this in turn implies a linear relationship between dose and biological effect across all doses. This paper examines whether the microdosimetric argument holds at the lowest levels of biological organization following low dose, low dose-rate exposures to ionizing radiation. The assumptions of the microdosimetric argument are evaluated in light of recent radiobiological studies on radiation damage in biological molecules and cellular and tissue level responses to radiation damage. There is strong evidence that radiation initially deposits energy in biological molecules (e.g., DNA) in a linear fashion, and that this energy deposition results in various forms of prompt DNA damage that may be produced in a pattern that is distinct from endogenous (e.g., oxidative) damage. However, a large and rapidly growing body of radiobiological evidence indicates that cell and tissue level responses to this damage, particularly at low doses and/or dose-rates, are nonlinear and may exhibit thresholds. To the extent that responses observed at lower levels of biological organization in vitro are predictive of carcinogenesis observed in vivo, this evidence directly contradicts the assumptions upon which the microdosimetric argument is based.
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Affiliation(s)
- Brant A Ulsh
- National Institute for Occupational Safety and Health, 4676 Columbia Parkway, Mailstop C-46, Cincinnati, OH 45226, USA
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Brooks AL, Eberlein PE, Couch LA, Boecker BB. The role of dose-rate on risk from internally-deposited radionuclides and the potential need to separate dose-rate effectiveness factor (DREF) from the dose and dose-rate effectiveness factor (DDREF). HEALTH PHYSICS 2009; 97:458-469. [PMID: 19820455 DOI: 10.1097/hp.0b013e3181ac910e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In 1980, National Council on Radiation Protection and Measurements suggested the term dose-rate effectiveness factor (DREF) to describe the reduction of effectiveness of protracted radiation in producing biological damage and risk. A nonlinear decrease in damage was also noted following low total doses. The International Commission on Radiological Protection therefore combined the influence of low dose and low dose-rate and assigned a single value of 2.0 for a dose and dose-rate effectiveness factor (DDREF) to be applied for estimating risk for both low total dose and low dose-rate exposures. This paper re-evaluates one extensive data set on inhaled radionuclides in dogs which suggests that there may be a need to separate these factors (DREF and DDREF) for larger protracted doses from internally-deposited radioactive materials. Extensive recent research on the mechanisms of action of both low dose and low dose-rate radiation exposure at the molecular, cellular, and animal level of biological organization suggest that the influence of protraction of radiation may be large and variable, due to adaptive and protective responses, following very low doses and dose-rate exposures. Important observations in this paper in dogs exposed by inhalation to beta-gamma emitting radionuclides include (1) discontinuities in the data sets as a function of both dose and dose-rate suggesting shifts in mechanisms of action following high doses from protracted exposure away from those postulated for cancer from low total doses; (2) no increase in non-neoplastic disease, cancer frequency, or life-shortening following low dose-rate exposures to high total lung doses (up to 25 Gy); (3) all dogs that received doses below 25 Gy were combined and a decrease in the frequency of lung cancer in these exposed animals relative to the controls was noted, while very large doses from all radionuclides studied resulted in very marked increases in lung cancer; (4) a significant increase in hemangiosarcoma in the heart and tracheobronchial lymph nodes was observed after very high doses; (5) in this paper the DREF for lung cancer in dogs relative to single acute radiation exposure was as high as 35; and (6) the amount of life-shortening increased per unit dose as a function of the half-life with (90)Y being eight times as effective per unit of dose as (90)Sr. Such information suggests that there may be a need to assign different values for DDREF and DREF, especially in situations where there are large nonuniform total doses delivered by internally-deposited radionuclides. This is extremely important since the risk from radiation exposure from internally-deposited radionuclides in the lungs following nuclear fallout, accidents and terrorist activities may be much less than currently projected.
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Affiliation(s)
- Antone L Brooks
- Washington State University Tri-Cities, Richland, WA 99354, USA.
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Gruel G, Voisin P, Vaurijoux A, Roch-Lefevre S, Grégoire E, Maltere P, Petat C, Gidrol X, Voisin P, Roy L. Broad modulation of gene expression in CD4+ lymphocyte subpopulations in response to low doses of ionizing radiation. Radiat Res 2008; 170:335-44. [PMID: 18763857 DOI: 10.1667/rr1147.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Accepted: 04/17/2008] [Indexed: 11/03/2022]
Abstract
To compare the responses of the different lymphocyte subtypes after an exposure of whole blood to low doses of ionizing radiation, we examined variations in gene expression in different lymphocyte subpopulations using microarray technology. Blood samples from five healthy donors were independently exposed to 0 (sham irradiation), 0.05 and 0.5 Gy of ionizing radiation. Three and 24 h after exposure, CD56+, CD4+ and CD8+ cells were negatively isolated. RNA from each set of experimental conditions was competitively hybridized on 25k oligonucleotide microarrays. Modifications of gene expression were measured after both intervals and in all cell types. Twenty-four hours after exposure to 0.5 Gy, we observed an induction of the expression of BAX, PCNA, GADD45, DDB2 and CDKN1A. However, the numbers of modulated genes greatly differed between cell types. In particular, 3 h after exposure to doses as low as 0.05 Gy, the number of down-modulated genes was 10 times greater for CD4+ cells than for all other cell types. Moreover, most of these repressed genes were taking part in the cell processes of protein biosynthesis and oxidative phosphorylation. The results suggest that several biological pathways in CD4+ cells could be sensitive to low doses of radiation. Therefore, specifically studying CD4+ cells could help to understand the mechanisms involved in low-dose response and allow their detection.
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Affiliation(s)
- Gaëtan Gruel
- Laboratoire de Dosimétrie Biologique, Institut de Radioprotection et de Sûreté Nucléaire (IRSN), 92262 Fontenay-aux-Roses, France
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Ahuja AK, Barber RC, Hardwick RJ, Weil MM, Genik PC, Brenner DJ, Dubrova YE. The effects of Atm haploinsufficiency on mutation rate in the mouse germ line and somatic tissue. Mutagenesis 2008; 23:367-70. [PMID: 18499649 DOI: 10.1093/mutage/gen028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Using single-molecule polymerase chain reaction, the frequency of spontaneous and radiation-induced mutation at an expanded simple tandem repeat (ESTR) locus was studied in DNA samples extracted from sperm and bone marrow of Atm knockout (Atm(+/-)) heterozygous male mice. The frequency of spontaneous mutation in sperm and bone marrow in Atm(+/-) males did not significantly differ from that in wild-type BALB/c mice. Acute exposure to 1 Gy of gamma-rays did not affect ESTR mutation frequency in bone marrow and resulted in similar increases in sperm samples taken from Atm(+/-) and BALB/c males. Taken together, these results suggest that the Atm haploinsufficiency analysed in our study does not affect spontaneous and radiation-induced ESTR mutation frequency in mice.
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Affiliation(s)
- Akshay K Ahuja
- Department of Genetics, University of Leicester, Leicester LE1 7RH, UK
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