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Ahmad IM, Temme JB, Abdalla MY, Zimmerman MC. Redox status in workers occupationally exposed to long-term low levels of ionizing radiation: A pilot study. Redox Rep 2016; 21:139-45. [PMID: 26817988 DOI: 10.1080/13510002.2015.1101891] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
OBJECTIVES Reactive oxygen species (ROS), including superoxide (O2(•-)), play an important role in the biological effects of ionizing radiation. The human body has developed different antioxidant systems to defend against excessive levels of ROS. The aim of the present study is to investigate the redox status changes in the blood of radiologic technologists and compare these changes to control individuals. METHODS We enrolled 60 medical workers: 20 occupationally exposed to ionizing radiation (all radiologic technologists), divided in three subgroups: conventional radiography (CR), computerized tomography (CT), and interventional radiography (IR) and 40 age- and gender-matched unexposed controls. Levels of O2(•-) and malondialdehyde (MDA) in blood were measured as an index of redox status, as were the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase. Redox status was also assessed by measuring levels of reduced and oxidized glutathione (GSH, GSSG, respectively). RESULTS Levels of O2(•-) and MDA, and SOD activity in the blood of IR and CT-exposed subjects were significantly higher than both the CR-exposed subjects and control individuals. However, there were no statistically significant differences in the levels of catalase, GSH and ratio of GSH/GSSG between exposed workers and control individuals. DISCUSSION This study suggests that healthcare workers in CT and IR occupationally exposed to radiation have an elevated circulating redox status as compared to unexposed individuals.
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Affiliation(s)
- Iman M Ahmad
- a Radiation Science Technology Education, College of Allied Health Professions , University of Nebraska Medical Center , Omaha , USA
| | - James B Temme
- a Radiation Science Technology Education, College of Allied Health Professions , University of Nebraska Medical Center , Omaha , USA
| | - Maher Y Abdalla
- b Department of Pathology and Microbiology , University of Nebraska Medical Center , Omaha , USA
| | - Matthew C Zimmerman
- c Department of Cellular and Integrative Physiology , University of Nebraska Medical Center , Omaha , USA
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Kraft D, Ritter S, Durante M, Seifried E, Fournier C, Tonn T. Transmission of clonal chromosomal abnormalities in human hematopoietic stem and progenitor cells surviving radiation exposure. Mutat Res 2015; 777:43-51. [PMID: 25938904 DOI: 10.1016/j.mrfmmm.2015.04.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 03/18/2015] [Accepted: 04/06/2015] [Indexed: 12/15/2022]
Abstract
In radiation-induced acute myeloid leukemia (rAML), clonal chromosomal abnormalities are often observed in bone marrow cells of patients, suggesting that their formation is crucial in the development of the disease. Since rAML is considered to originate from hematopoietic stem and progenitor cells (HSPC), we investigated the frequency and spectrum of radiation-induced chromosomal abnormalities in human CD34(+) cells. We then measured stable chromosomal abnormalities, a possible biomarker of leukemia risk, in clonally expanded cell populations which were grown for 14 days in a 3D-matrix (CFU-assay). We compared two radiation qualities used in radiotherapy, sparsely ionizing X-rays and densely ionizing carbon ions (29 and 60-85 keV/μm, doses between 0.5 and 4 Gy). Only a negligible number of de novo arising, unstable aberrations (≤ 0.05 aberrations/cell, 97% breaks) were measured in the descendants of irradiated HSPC. However, stable aberrations were detected in colonies formed by irradiated HSPC. All cells of the affected colonies exhibited one or more identical aberrations, indicating their clonal origin. The majority of the clonal rearrangements (92%) were simple exchanges such as translocations (77%) and pericentric inversions (15%), which are known to contribute to the development of rAML. Carbon ions were more efficient in inducing cell killing (maximum of ∼ 30-35% apoptotic cells for 2 Gy carbon ions compared to ∼ 25% for X-rays) and chromosomal aberrations in the first cell-cycle after exposure (∼ 70% and ∼ 40% for 1 Gy of carbon ions and X-rays, respectively), with a higher fraction of non-transmissible aberrations. In contrast, for both radiation qualities the percentage of clones with chromosomal abnormalities was similar (40%). Using the frequency of colonies with clonal aberrations as a surrogate marker for the leukemia risk following radiotherapy of solid tumors, charged particle therapy is not expected to lead to an increased risk of leukemia in patients.
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Affiliation(s)
- Daniela Kraft
- GSI Helmholtz Center for Heavy Ion Research, Department of Biophysics, Planckstr. 1, 64291 Darmstadt, Germany; Institute for Transfusion Medicine und Immunohematology, DRK-Blutspendedienst Baden-Wuerttemberg-Hessen, Johann Wolfgang Goethe-University Hospital, Sandhofstrasse 1, 60528 Frankfurt, Germany.
| | - Sylvia Ritter
- GSI Helmholtz Center for Heavy Ion Research, Department of Biophysics, Planckstr. 1, 64291 Darmstadt, Germany.
| | - Marco Durante
- GSI Helmholtz Center for Heavy Ion Research, Department of Biophysics, Planckstr. 1, 64291 Darmstadt, Germany; Institute for Condensed Matter Physics, Physics Department, Technical University Darmstadt, Hochschulstraße 6-8, 64289 Darmstadt, Germany.
| | - Erhard Seifried
- Institute for Transfusion Medicine und Immunohematology, DRK-Blutspendedienst Baden-Wuerttemberg-Hessen, Johann Wolfgang Goethe-University Hospital, Sandhofstrasse 1, 60528 Frankfurt, Germany.
| | - Claudia Fournier
- GSI Helmholtz Center for Heavy Ion Research, Department of Biophysics, Planckstr. 1, 64291 Darmstadt, Germany.
| | - Torsten Tonn
- Institute for Transfusion Medicine und Immunohematology, DRK-Blutspendedienst Baden-Wuerttemberg-Hessen, Johann Wolfgang Goethe-University Hospital, Sandhofstrasse 1, 60528 Frankfurt, Germany; Technische Universität Dresden, Med. Fakultät Carl Gustav Carus; Institute for Transfusion Medicine Dresden, German Red Cross Blood Donation Service North-East, Blasewitzer Straße 68/70, 01307 Dresden, Germany.
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Mothersill C, Smith R, Lariviere D, Seymour C. Chronic exposure by ingestion of environmentally relevant doses of (226)Ra leads to transient growth perturbations in fathead minnow (Pimephales promelas, Rafinesque, 1820). Int J Radiat Biol 2013; 89:950-64. [PMID: 23724911 DOI: 10.3109/09553002.2013.809817] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE To assess the impact of environmentally relevant levels of ingested (226)Ra on a common freshwater fish species. METHODS Fathead minnow (Pimephales promelas, Rafinesque) were obtained at the first feeding stage and established on a commercial fish food diet containing (226)Ra in the activity range 10 mBq/g(-1), -10,000 mBq/g(-1). They remained on this diet for 24 months and were sampled invasively at 1,6,18 and 24 months to assess growth, biochemical indices and accumulated dose and non-invasively also at 12 and 15 months to assess growth. RESULTS Fish fed 10 and 100 mBq/g(-1) diet showed a small transitory deregulation of growth at 6 and 12 months. Fish fed higher activities showed less significant or insignificant effects. There was a trend at 18 months which was stronger at 24 months for the population distribution to change in all of the (226)Ra fed groups so that smaller fish were smaller and bigger fish were bigger than the controls. There were also significant differences in the ratios of protein:DNA at 24 months which were seen as a trend but were not significant at earlier time points. CONCLUSIONS Fish fed a radium diet for 2 years show a small and transitory growth dysregulation at 6 and 12 months. The effects predominate at the lower activities suggesting hormetic or homeostatic adjustments. There was no effect on growth of exposure to the high activities (226)Ra. This suggests that radium does not have a serious impact on the ecology of the system and the level of radium that would be transferred to humans is very low. The results may be important in the assessment of long-term environmental impacts of (226)Ra exposure.
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Affiliation(s)
- Carmel Mothersill
- Department of Medical Physics and Applied Radiation Sciences, McMaster University , Hamilton, Ontario
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Autsavapromporn N, de Toledo SM, Little JB, Jay-Gerin JP, Harris AL, Azzam EI. The role of gap junction communication and oxidative stress in the propagation of toxic effects among high-dose α-particle-irradiated human cells. Radiat Res 2011; 175:347-57. [PMID: 21388278 PMCID: PMC3139025 DOI: 10.1667/rr2372.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We investigated the roles of gap junction communication and oxidative stress in modulating potentially lethal damage repair in human fibroblast cultures exposed to doses of α particles or γ rays that targeted all cells in the cultures. As expected, α particles were more effective than γ rays at inducing cell killing; further, holding γ-irradiated cells in the confluent state for several hours after irradiation promoted increased survival and decreased chromosomal damage. However, maintaining α-particle-irradiated cells in the confluent state for various times prior to subculture resulted in increased rather than decreased lethality and was associated with persistent DNA damage and increased protein oxidation and lipid peroxidation. Inhibiting gap junction communication with 18-α-glycyrrhetinic acid or by knockdown of connexin43, a constitutive protein of junctional channels in these cells, protected against the toxic effects in α-particle-irradiated cell cultures during confluent holding. Upregulation of antioxidant defense by ectopic overexpression of glutathione peroxidase protected against cell killing by α particles when cells were analyzed shortly after exposure. However, it did not attenuate the decrease in survival during confluent holding. Together, these findings indicate that the damaging effect of α particles results in oxidative stress, and the toxic effects in the hours after irradiation are amplified by intercellular communication, but the communicated molecule(s) is unlikely to be a substrate of glutathione peroxidase.
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Affiliation(s)
- Narongchai Autsavapromporn
- Department of Radiology, UMDNJ – New Jersey Medical School Cancer Center, Newark, New Jersey 07103
- Département de Médecine Nucléaire et de Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke (Québec) J1H 5N4, Canada
| | - Sonia M. de Toledo
- Department of Radiology, UMDNJ – New Jersey Medical School Cancer Center, Newark, New Jersey 07103
| | - John B. Little
- Laboratory of Radiobiology, Harvard School of Public Health, Boston, Massachusetts 02115
| | - Jean-Paul Jay-Gerin
- Département de Médecine Nucléaire et de Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke (Québec) J1H 5N4, Canada
| | - Andrew L. Harris
- Department of Pharmacology and Physiology, UMDNJ – New Jersey Medical School, Newark, New Jersey 07103
| | - Edouard I. Azzam
- Department of Radiology, UMDNJ – New Jersey Medical School Cancer Center, Newark, New Jersey 07103
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Glover D, Little JB, Lavin MF, Gueven N. Low dose ionizing radiation‐induced activation of connexin 43 expression. Int J Radiat Biol 2009; 79:955-64. [PMID: 14713573 DOI: 10.1080/09553000310001632895] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE Connexin 43 has been implicated in the cellular response to ionizing radiation by enabling cell-to-cell communication. It is established here that the expression of connexin 43 is affected by ionizing radiation and the mechanism involved is investigated. MATERIALS AND METHODS The human connexin 43 promoter was cloned into a Luciferase reporter plasmid and activation by ionizing radiation was measured in normal human fibroblasts as well as HeLa cells. The regions responsible for the radiation inducibility were defined using deletion and point mutations of the construct. The results were confirmed by Northern and Western blotting. RESULTS Ionizing radiation activates the human connexin 43 promoter in a time- and dose-dependent manner with a maximal induction (4.2-fold +/-0.58) after 6 h and a dose of 0.5 Gy. Higher doses up to 5 Gy led to a less marked increase (2-fold) over the same period. This promoter activation was associated with comparable increases in both connexin 43 mRNA and protein levels. The low dose radiation response of the promoter is mainly dependent on consensus binding sites for nuclear factor of activated T-cells (NFAT) and activator protein (AP1) in a region -2537 and -2110 bp from the transcriptional start site as determined by mutation analysis. CONCLUSIONS Low doses of ionizing radiation induce the transcriptional upregulation of connexin 43 expression employing NFAT and AP1 sites.
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Affiliation(s)
- D Glover
- Queensland Institute of Medical Research, Herston, Australia
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Intracellular redox status and oxidative stress: implications for cell proliferation, apoptosis, and carcinogenesis. Arch Toxicol 2008; 82:273-99. [PMID: 18443763 DOI: 10.1007/s00204-008-0304-z] [Citation(s) in RCA: 303] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Accepted: 04/03/2008] [Indexed: 02/06/2023]
Abstract
Oxidative stress can be defined as the imbalance between cellular oxidant species production and antioxidant capability. Reactive oxygen species (ROS) are involved in a variety of different cellular processes ranging from apoptosis and necrosis to cell proliferation and carcinogenesis. In fact, molecular events, such as induction of cell proliferation, decreased apoptosis, and oxidative DNA damage have been proposed to be critically involved in carcinogenesis. Carcinogenicity and aging are characterized by a set of complex endpoints, which appear as a series of molecular reactions. ROS can modify many intracellular signaling pathways including protein phosphatases, protein kinases, and transcription factors, suggesting that the majority of the effects of ROS are through their actions on signaling pathways rather than via non-specific damage of macromolecules; however, exact mechanisms by which redox status induces cells to proliferate or to die, and how oxidative stress can lead to processes evoking tumor formation are still under investigation.
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Azzam EI, de Toledo SM, Little JB. Oxidative metabolism, gap junctions and the ionizing radiation-induced bystander effect. Oncogene 2003; 22:7050-7. [PMID: 14557810 DOI: 10.1038/sj.onc.1206961] [Citation(s) in RCA: 239] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Evidence accumulated over the past two decades has indicated that exposure of cell populations to ionizing radiation results in significant biological effects occurring in both the irradiated and nonirradiated cells in the population. This phenomenon, termed the 'bystander response', has been shown to occur both in vitro and in vivo and has been postulated to impact both the estimation of risks of exposure to low doses/low fluences of ionizing radiation and radiotherapy. Several mechanisms involving secreted soluble factors, oxidative metabolism and gap-junction intercellular communication have been proposed to regulate the radiation-induced bystander effect. Our current knowledge of the biochemical and molecular events involved in the latter two processes is reviewed in this article.
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Affiliation(s)
- Edouard I Azzam
- Department of Radiology, UMDNJ, New Jersey Medical School, Newark, NJ 07103,
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Bishayee A, Hill HZ, Stein D, Rao DV, Howell RW. Free radical-initiated and gap junction-mediated bystander effect due to nonuniform distribution of incorporated radioactivity in a three-dimensional tissue culture model. Radiat Res 2001; 155:335-44. [PMID: 11175669 PMCID: PMC3495610 DOI: 10.1667/0033-7587(2001)155[0335:friagj]2.0.co;2] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
To investigate the biological effects of nonuniform distribution of radioactivity in mammalian cells, we have developed a novel three-dimensional tissue culture model. Chinese hamster V79 cells were labeled with tritiated thymidine and mixed with unlabeled cells, and multicellular clusters (approximately 1.6 mm in diameter) were formed by gentle centrifugation. The short-range beta particles emitted by (3)H impart only self-irradiation of labeled cells without significant cross-irradiation of unlabeled bystander cells. The clusters were assembled in the absence or presence of 10% dimethyl sulfoxide (DMSO) and/or 100 microM lindane. DMSO is a hydroxyl radical scavenger, whereas lindane is an inhibitor of gap junctional intercellular communication. The clusters were maintained at 10.5 degrees C for 72 h to allow (3)H decays to accumulate and then dismantled, and the cells were plated for colony formation. When 100% of the cells were labeled, the surviving fraction was exponentially dependent on the mean level of radioactivity per labeled cell. A two-component exponential response was observed when either 50 or 10% of the cells were labeled. Though both DMSO and lindane significantly protected the unlabeled or bystander cells when 50 or 10% of the cells were labeled, the effect of lindane was greater than that of DMSO. In both cases, the combined treatment (DMSO + lindane) elicited maximum protection of the bystander cells. These results suggest that the bystander effects caused by nonuniform distributions of radioactivity are affected by the fraction of cells that are labeled. Furthermore, at least a part of these bystander effects are initiated by free radicals and are likely to be mediated by gap junctional intercellular communication.
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Affiliation(s)
- A Bishayee
- Division of Radiation Research, Department of Radiology, University of Medicine and Dentistry of New Jersey, 07103, USA
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