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Ramachandran EN, Karuppasamy CV, Kumar VA, Soren DC, Kumar PRV, Koya PKM, Jaikrishan G, Das B. Radio-adaptive response in peripheral blood lymphocytes of individuals residing in high-level natural radiation areas of Kerala in the southwest coast of India. Mutagenesis 2017; 32:267-273. [PMID: 27831478 DOI: 10.1093/mutage/gew057] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The present study investigates whether the chronic low-dose radiation exposure induces an in vivo radio-adaptive response in individuals from high-level natural radiation areas (HLNRA) of the Kerala coast. Peripheral blood samples from 54 adult male individuals aged between 26 and 65 years were collected for the study with written informed consent. Each of the whole blood sample was divided into three, one was sham irradiated, second and third was exposed to challenging doses of 1.0 and 2.0 Gy gamma radiation, respectively. Cytokinesis-block micronucleus (CBMN) assay was employed to study the radio-adaptive response. Seventeen individuals were from normal-level natural radiation area (NLNRA ≤1.5 mGy/year) and 37 from HLNRA (> 1.5 mGy/year). Based on the annual dose received, individuals from HLNRA were further classified into low-dose group (LDG, 1.51-5.0 mGy/year, N = 19) and high-dose group (HDG >5.0 mGy/year, N = 18). Basal frequency of micronucleus (MN) was comparable across the three dose groups (NLNRA, LDG and HDG, P = 0.64). Age of the individuals showed a significant effect on the frequency of MN after challenging dose exposures. The mean frequency of MN was significantly lower in elder (>40 years) individuals from HDG of HLNRA as compared to the young (≤40 years) individuals after 1.0 Gy (P < 0.001) and 2.0 Gy (P = 0.002) of challenging doses. However, young and elder individuals within NLNRA and LDG of HLNRA showed similar frequency of MN after the challenging dose exposures. Thus, increased level of chronic low-dose radiation (>5.0 mGy/year) seems to act as a priming dose resulting in the induction of an in vivo radio-adaptive response in elder individuals of the Kerala coast.
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Affiliation(s)
- E N Ramachandran
- Low Level Radiation Research Laboratory (LLRRL), Radiation Biology and Health Sciences Division (RB&HSD), Bio-Science Group, Bhabha Atomic Research Centre (BARC), Beach Road, Kollam 691 001, Kerala and
| | - C V Karuppasamy
- Low Level Radiation Research Laboratory (LLRRL), Radiation Biology and Health Sciences Division (RB&HSD), Bio-Science Group, Bhabha Atomic Research Centre (BARC), Beach Road, Kollam 691 001, Kerala and
| | - V Anil Kumar
- Low Level Radiation Research Laboratory (LLRRL), Radiation Biology and Health Sciences Division (RB&HSD), Bio-Science Group, Bhabha Atomic Research Centre (BARC), Beach Road, Kollam 691 001, Kerala and
| | - D C Soren
- Low Level Radiation Research Section (LLRRS), RB&HSD, Bio-Science Group, BARC, Trombay, Mumbai 400 085, India
| | - P R Vivek Kumar
- Low Level Radiation Research Laboratory (LLRRL), Radiation Biology and Health Sciences Division (RB&HSD), Bio-Science Group, Bhabha Atomic Research Centre (BARC), Beach Road, Kollam 691 001, Kerala and
| | - P K M Koya
- Low Level Radiation Research Laboratory (LLRRL), Radiation Biology and Health Sciences Division (RB&HSD), Bio-Science Group, Bhabha Atomic Research Centre (BARC), Beach Road, Kollam 691 001, Kerala and
| | - G Jaikrishan
- Low Level Radiation Research Laboratory (LLRRL), Radiation Biology and Health Sciences Division (RB&HSD), Bio-Science Group, Bhabha Atomic Research Centre (BARC), Beach Road, Kollam 691 001, Kerala and
| | - Birajalaxmi Das
- Low Level Radiation Research Section (LLRRS), RB&HSD, Bio-Science Group, BARC, Trombay, Mumbai 400 085, India
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Kumar PRV, Seshadri M, Jaikrishan G, Das B. Effect of chronic low dose natural radiation in human peripheral blood mononuclear cells: Evaluation of DNA damage and repair using the alkaline comet assay. Mutat Res 2015; 775:59-65. [PMID: 25879710 DOI: 10.1016/j.mrfmmm.2015.03.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 03/15/2015] [Accepted: 03/22/2015] [Indexed: 06/04/2023]
Abstract
This study investigates whether peripheral blood mononuclear cells (PBMCs) from inhabitants of Kerala in southwest India, exposed to chronic low dose natural radiation in vivo (>1 mSv year(-1)), respond with a radioadaptive response to a challenging dose of gamma radiation. Toward this goal, PBMCs isolated from 77 subjects from high-level natural radiation areas (HLNRA) and 37 subjects from a nearby normal level natural radiation area (NLNRA) were challenged with 2 Gy and 4 Gy gamma radiation. Subjects from HLNRA were classified based on the mean annual effective dose received, into low dose group (LDG) and high dose group (HDG) with mean annual effective doses of 2.69 mSv (N=43, range 1.07 mSv year(-1) to 5.55 mSv year(-1)) and 9.62 mSv (N = 34, range 6.07 mSv year(-1) to 17.41 mSv year(-1)), respectively. DNA strand breaks and repair kinetics (at 7 min, 15 min and 30 min after 4 Gy) were evaluated using the alkaline single cell gel electrophoresis (comet) assay. Initial levels of DNA strand breaks observed after either a 2 Gy or a 4 Gy challenging dose were significantly lower in subjects of the HDG from HLNRA compared to subjects of NLNRA (2 Gy, P = 0.01; 4 Gy, P = 0.02) and LDG (2 Gy P = 0.01; 4 Gy, P=0.05). Subjects of HDG from HLNRA showed enhanced rejoining of DNA strand breaks (HDG/NLNRA, P = 0.06) during the early stage of repair (within 7 min). However at later times a similar rate of rejoining of strand breaks was observed across the groups (HDG, LDG and NLNRA). Preliminary results from our study suggest in vivo chronic low-level natural radiation provides an initial exposure that allows an adaptation to a subsequent higher radiation exposure, perhaps through improving DNA repair via an unknown mechanism. Therefore, further investigations would be necessary in this population to understand the biological and health effects of chronic low-level natural radiation exposures.
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Affiliation(s)
- P R Vivek Kumar
- Low Level Radiation Research Laboratory, Radiation Biology and Health Sciences Division, Bio-Science Group, Bhabha Atomic Research Centre, IRE Campus, Beach Road, Kollam 691 001, Kerala, India.
| | - M Seshadri
- Low Level Radiation Research Section, Radiation Biology and Health Sciences Division, Bio-Science Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
| | - G Jaikrishan
- Low Level Radiation Research Laboratory, Radiation Biology and Health Sciences Division, Bio-Science Group, Bhabha Atomic Research Centre, IRE Campus, Beach Road, Kollam 691 001, Kerala, India
| | - Birajalaxmi Das
- Low Level Radiation Research Section, Radiation Biology and Health Sciences Division, Bio-Science Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India
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Galván I, Bonisoli-Alquati A, Jenkinson S, Ghanem G, Wakamatsu K, Mousseau TA, Møller AP. Chronic exposure to low-dose radiation at Chernobyl favours adaptation to oxidative stress in birds. Funct Ecol 2014. [DOI: 10.1111/1365-2435.12283] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Ismael Galván
- Laboratoire d'Ecologie, Systématique et Evolution; CNRS UMR 8079; Université Paris-Sud 11; Bâtiment 362 91405 Orsay Cedex France
| | | | - Shanna Jenkinson
- Department of Biological Sciences; University of South Carolina; Columbia SC 29208 USA
| | - Ghanem Ghanem
- Laboratoire d'Oncologie et de Chirurgie Expérimentale (L.O.C.E.); Institut Jules Bordet; Université Libre de Bruxelles; rue Héger-Bordet 1 1000 Bruxelles Belgium
| | - Kazumasa Wakamatsu
- Department of Chemistry; Fujita Health University School of Health Sciences; Toyoake Aichi 470-1192 Japan
| | - Timothy A. Mousseau
- Department of Biological Sciences; University of South Carolina; Columbia SC 29208 USA
| | - Anders P. Møller
- Laboratoire d'Ecologie, Systématique et Evolution; CNRS UMR 8079; Université Paris-Sud 11; Bâtiment 362 91405 Orsay Cedex France
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Kilemade M, Lemon J, Boreham D. Characteristics of the adaptive response in cultured salmon cells exposed to ionizing radiation. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:165-172. [PMID: 18095328 DOI: 10.1002/em.20354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The aim of this study was to investigate the influence of "priming" doses of ionizing irradiation on salmon cell survival in vitro prior to being challenged with subsequent higher doses. A radiation-induced adaptive response (AR) was examined in the Chinook salmon embryo cell line (CHSE-214). Cells were initially irradiated with a range of priming (conditioning) doses of (60)Co gamma (gamma) rays (0.25-0.75 Gy), followed by a challenge dose of 7.50 Gy at intervals of 24, 48, and 72 hr. The AR was assessed using a colony-forming assay. Cell survival was determined by counting the number of colonies (viable clones) after 40 days of culture. This study revealed that cells that received a priming dose of 0.50 Gy before delivering the higher challenge dose became more radiation resistant with an increase in cell survival of 29% over cells receiving the challenge dose alone. The cells showed maximum resistance to ionizing radiation when the priming dose was given 72 hr prior to the higher challenge dose. This study is one of the first to demonstrate an AR using an in vitro piscine system, and is generally consistent with other studies of both in vitro and in vivo systems across the taxa.
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Affiliation(s)
- Michael Kilemade
- Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada
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Tapio S, Jacob V. Radioadaptive response revisited. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2007; 46:1-12. [PMID: 17131131 DOI: 10.1007/s00411-006-0078-8] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Accepted: 10/27/2006] [Indexed: 05/12/2023]
Abstract
Radiation-induced adaptive response belongs to the group of non-targeted effects that do not require direct exposure of the cell nucleus by radiation. It is described as the reduced damaging effect of a challenging radiation dose when induced by a previous low priming dose. Adaptive responses have been observed in vitro and in vivo using various indicators of cellular damage, such as cell lethality, chromosomal aberrations, mutation induction, radiosensitivity, and DNA repair. Adaptive response can be divided into three successive biological phenomena, the intracellular response, the extracellular signal, and the maintenance. The intracellular response leading to adaptation of a single cell is a complex biological process including induction or suppression of gene groups. An extracellular signal, the nature of which is unknown, may be sent by the affected cell to neighbouring cells causing them to adapt as well. This occurs either by a release of diffusible signalling molecules or by gap-junction intercellular communication. Adaptive response can be maintained for periods ranging from of a few hours to several months. Constantly increased levels of reactive oxygen species (ROS) or nitric oxide (NO) have been observed in adapted cells and both factors may play a role in the maintenance process. Although adaptive response seems to function by an on/off principle, it is a phenomenon showing a high degree of inter- and intraindividual variability. It remains to be seen to what extent adaptive response is functional in humans at relevant dose and dose-rate exposures. A better understanding of adaptive response and other non-targeted effects is needed before they can be confirmed as risk estimate factors for the human population at low levels of ionising radiation.
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Affiliation(s)
- Soile Tapio
- Department of Radiation Protection and Health, Federal Office for Radiation Protection, Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany.
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Morgan WF. Will radiation-induced bystander effects or adaptive responses impact on the shape of the dose response relationships at low doses of ionizing radiation? Dose Response 2006; 4:257-62. [PMID: 18648589 DOI: 10.2203/dose-response.06-110.morgan] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Radiation induced bystander effects and adaptive responses are two phenomena that modulate cellular responses to low doses of ionizing radiation. Bystander effects generally exaggerate the effects of low doses of radiation by eliciting detrimental effects in nonirradiated cells, thus making the target for radiation effects greater than the volume irradiated. Adaptive responses on the other hand indicate that low doses of radiation can reduce damage induced by a second challenging dose. The potential impact of these two low dose effects on the shape of the dose response relationship will be discussed.
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Affiliation(s)
- William F Morgan
- Radiation Oncology Research Laboratory, University of Maryland, 655 West Baltimore Street, Baltimore, MD 21201-1509, USA.
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Au WW. Mutagen sensitivity assays in population studies. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2003; 544:273-7. [PMID: 14644328 DOI: 10.1016/j.mrrev.2003.10.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Human population monitoring studies are frequently conducted to determine if exposure to environmental mutagenic agents can cause health problems or not. In these studies, a variety of biomarkers are used to identify biological events that are predictive of health consequences. An emphasis in this report is on the use of mutagen sensitivity assays to understand health risk. The assay is based on the assumption that exposure to mutagenic chemicals or mixtures of chemicals for a long time can cause cellular changes that are expressed as mutagen sensitivity. From experience in using these assays in cancer patients and in mutagen-exposed populations, it is clear that the expression of mutagen sensitivity is based on the interactions between mutagen exposure and individual susceptibility. When studies are conducted under appropriate conditions, expression of mutagen sensitivity is suggestive of increased risk for environmental disease such as cancer.
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Affiliation(s)
- William W Au
- Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, 700 Harborside Drive, Galveston, TX 77555-1110, USA.
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Vaglenov A, Nosko M, Georgieva R, Carbonell E, Creus A, Marcos R. Genotoxicity and radioresistance in electroplating workers exposed to chromium. Mutat Res 1999; 446:23-34. [PMID: 10613183 DOI: 10.1016/s1383-5718(99)00145-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A biomonitoring study was carried out to investigate the genetic risk associated to occupational exposure to chromium. The induction of genetic damage was measured by analysing the frequency of micronuclei (MN) in peripheral blood lymphocytes. In addition to the 40 electroplater exposed workers who participated in the study, a group constituted by 18 volunteer donors, without exposure to chromium, was analysed as a control group. Measures of chromium levels at working place and in erythrocytes and urine were obtained, as indicators of exposure. The results from this study indicate that the blood from exposed workers contained higher levels of chromium, when compared with those obtained in the control group, and that a significant increase in the frequency of both the total number of MN and the number of binucleated cells carrying MN (BNMN) was detected. Furthermore, a good direct relationship was obtained between the amount of chromium present in air, erythrocytes or urine and the frequency of MN. To determine the existence of radioresistance as consequence of chromium exposure, the response of lymphocytes to the in vitro gamma-radiation was studied. The results of this experiment show a lower induction in the increase of the frequency of MN after challenge irradiation in the lymphocytes of chromium exposed workers, which should be indicative of an adaptive response.
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Affiliation(s)
- A Vaglenov
- National Centre of Radiobiology and Radiation Protection, Sofia, Bulgaria
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Fleck CM, Schöllnberger H, Kottbauer MM, Dockal T, Prüfert U. Modeling radioprotective mechanisms in the dose effect relation at low doses and low dose rates of ionizing radiation. Math Biosci 1999; 155:13-44. [PMID: 10024833 DOI: 10.1016/s0025-5564(98)10053-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A new model (Random Coincidence Model--Radiation Adapted (RCM-RA)) is proposed which explains a possible pseudo threshold for stochastic radiation effects. It describes the formation of cancer in the case of multistep fixation of lesions in the critical regions of tumor associated genes such as proto-oncogenes or tumor-suppressor genes. The RCM-RA contains two different possibilities of DNA damage to complementary nucleotides. The damage may be caused either by radiation or by natural processes such as cellular radicals or thermal damage or by chemical cytotoxins. The model is based on the premise that radiation initially is bionegative, damaging organisms at their different levels of organization. The radiation, however, also induces various cellular radioprotective mechanisms which decrease the damage by natural processes. Considering both effects together, the theory explains apparent thresholds in the dose-response relation for radiation carcinogenesis without contradiction to the classical assumption that radiation is predominantly bionegative at doses typically found in occupational exposures.
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Affiliation(s)
- C M Fleck
- Atominstitut der Osterreichischen Universitäten, Wien, Austria
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Vaglenov A, Carbonell E, Marcos R. Biomonitoring of workers exposed to lead. Genotoxic effects, its modulation by polyvitamin treatment and evaluation of the induced radioresistance. Mutat Res 1998; 418:79-92. [PMID: 9757002 DOI: 10.1016/s1383-5718(98)00111-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A population monitoring study was performed, by using the micronucleus (MN) assay in human peripheral lymphocytes, to investigate whether occupational exposure to lead is genotoxic to workers. In addition to the exposed workers group, two more groups were studied, an external group from a factory without exposure to lead and an internal control group, from the same factory as the exposed workers, but that were not directly exposed to lead. Measures of lead levels at working place and in blood were calculated, and blood samples were collected to carry out a MN study. The results from these studies indicate that the blood from workers directly exposed contained high levels of lead, compared with the other groups, and a significant increase in the frequency of both the total number of MN and the number of binucleated cells carrying MN appeared. In addition, a study on the antimutagenic effects of a polyvitamin rich diet was conducted by measuring the frequency of MN after the workers had a four month daily intake of a polyvitamin-polymineral complex. These results clearly show a significant reduction of the MN frequency evaluated after this treatment, obtaining values that were even lower than those obtained in the internal control group. Finally, a challenge assay was carried out to determine response to gamma-radiation as indication of any kind of radiosensitivity or radioresistance. The results of this experiment did not show any significant variation in the increase of the frequency of MN after challenge irradiation in the lead exposed workers; nevertheless this increase was significantly reduced in the sample obtained after the polyvitamin treatment indicating a radioresistance response.
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Affiliation(s)
- A Vaglenov
- National Centre of Radiobiology and Radiation Protection, Boul. Kliment Ohridski 132, 1750, Sofia, Bulgaria
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Peterson LE, Dreyer ZE, Plon SE, Smith JL, Weinberg AD, McCarthy PL. Design and analysis of epidemiological studies of excess cancer among children exposed to Chernobyl radionuclides. Stem Cells 1997; 15 Suppl 2:211-30. [PMID: 9368307 DOI: 10.1002/stem.5530150730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Within the last decade, a substantial amount of attention has been devoted to etiological research on the association between exposure to fallout radionuclides from the Chernobyl accident and radiation-induced late effects (cancer) among children. A majority of the studies completed to date have been of the descriptive type, which only correlate average population exposure with average rate of cancer incidence as a function of calendar period. Since individual dosimetry is not performed in descriptive studies, it is unclear whether exposure precedes the development of cancer and a final decision cannot be made regarding the association between radiation exposure and cancer. This paper reviews the background epidemiology and outlines an analytical study design that is needed to clarify the unclear association between Chernobyl fallout exposure and childhood cancer. We discuss the essential elements of an analytical case-control design such as genetic predisposition, vital statistics, sample size and power determinations, ascertainment of cases and controls, and phenomenological dose modeling to establish individual doses. Examples such as cytogenetic biodosimetry, medical radiation dosimetry, and cytogenetic characterization of leukemia to minimize exposure and diagnostic misclassification are provided. We recommend the analytical methods described in this paper for studying the role of Chernobyl radionuclides and development of childhood cancer.
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Affiliation(s)
- L E Peterson
- Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
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Chen WL, Taur CL, Tai JJ, Wuu KD, Wang-Wuu S. Chromosomal study in lymphocytes from subjects living or working in buildings constructed with radioactively contaminated rebar. Mutat Res 1997; 377:247-54. [PMID: 9247621 DOI: 10.1016/s0027-5107(97)00081-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
It has recently been found that many buildings in Taiwan were constructed with radioactively contaminated rebar, which raised great concern among the residents as well as governmental officials. In order to investigate the possible cytogenetic damage to the residents of contaminated buildings, a G-banding method was carried out on the lymphocytes of 30 radiation-exposed individuals from four families and one office building, as well as 15 control individuals from laboratory personnel. The estimated cumulative radiation doses for the exposed people range from 19.63 to 280.50 mSv. Altogether, 13 females and 17 males belonging to the radiation-exposed group, and 7 females and 8 males in the control group, were included in this study. With the exception of one sample, at least 500 metaphase spreads were scored and analyzed for each individual. All the recognizable structural aberrations of chromosomes or chromatids were recorded and statistically analyzed. Comparison of either percentage of cells with chromosome aberrations or number of aberrated chromosomes per 100 cells between the radiation-exposed and the control groups manifested insignificant differences (p = 0.1145 and 0.0766, respectively). In addition, the chromosomal regions close to the centromere were found to break more frequently than elsewhere in the genome.
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Affiliation(s)
- W L Chen
- Department of Radiation Protection, Atomic Energy Council, Taipei, Taiwan, ROC
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Tedeschi B, Caporossi D, Vernole P, Padovani L, Appolloni M, Anzidei P, Mauro F. Do human lymphocytes exposed to the fallout of the Chernobyl accident exhibit an adaptive response? 2. Challenge with bleomycin. Mutat Res 1995; 332:39-44. [PMID: 7500990 DOI: 10.1016/0027-5107(95)00119-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The present study concerns the possible adaptive response, induced in vivo by a continuous exposure to ionizing radiations, to a challenge treatment with the radiomimetic glycopeptide bleomycin (BLM). Lymphocytes from children contaminated as a consequence of Chernobyl accident were treated for the last 5 h of culture with 2.5 micrograms/ml BLM. The induced chromosome damage was significantly lower than that found with the same treatment in lymphocytes from control children. This hyposensitivity to BLM was still present if, 1 h after the addition of the drug, inhibitors of the enzymes involved in DNA repair, such as 3-aminobenzamide (2 mM), or aphidicolin (0.4 microM) or 3-dideoxythymidine (5 mM) were added to the cultures. The resistance to BLM in lymphocytes from contaminated children seems to be related to a mechanism upstream in respect to the activities of enzymes involved in the DNA repair and specifically linked to the action of this drug. This is consistent with the different response found when the cells were challenged with ionizing radiation in vitro, as reported in the accompanying paper (L. Padovani, L. et al. (1995) Mutation Res., this issue).
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Affiliation(s)
- B Tedeschi
- Department of Public Health and Cell Biology, University of Rome Tor Vergata, Italy
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