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Papenfuß F, Maier A, Sternkopf S, Fournier C, Kraft G, Friedrich T. Radon progeny measurements in a ventilated filter system to study respiratory-supported exposure. Sci Rep 2023; 13:10792. [PMID: 37402813 PMCID: PMC10319858 DOI: 10.1038/s41598-023-37697-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 06/26/2023] [Indexed: 07/06/2023] Open
Abstract
Radon (222Rn) and its progeny are responsible for half of the annual dose from natural radiation and the most frequent cause for lung cancer induction after smoking. During inhalation, progeny nuclides accumulate in the respiratory tract while most of the radon gas is exhaled. The decay of progeny nuclides in the lung together with the high radiosensitivity of this tissue lead to equivalent doses implying a significant cancer risk. Here, we use gamma spectroscopy to measure the attachment of radon progeny on an air-ventilated filter system within a radon enriched atmosphere, mimicking the respiratory tract. A mathematical model was developed to describe the measured time-dependent activities of radon progeny on the filter system. We verified a linear relation between the ambient radon activity concentration during exposure and the amount of decay products on the filter system. The measured activities on the filters and its mathematical description are in good agreement. The developed experimental set-up can thus serve to further investigate the deposition of radon progeny in the respiratory tract under varying conditions for determination of dose conversion factors in radiation protection, which we demonstrate by deriving dose estimations in mouse lung.
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Affiliation(s)
- Franziska Papenfuß
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, Darmstadt, Germany
| | - Andreas Maier
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, Darmstadt, Germany
| | - Sonja Sternkopf
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, Darmstadt, Germany
- Goethe Universität Frankfurt, Max-Von-Laue-Str. 1, Frankfurt, Germany
| | - Claudia Fournier
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, Darmstadt, Germany
| | - Gerhard Kraft
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, Darmstadt, Germany
| | - Thomas Friedrich
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, Darmstadt, Germany.
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2
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Mozzoni P, Pinelli S, Corradi M, Ranzieri S, Cavallo D, Poli D. Environmental/Occupational Exposure to Radon and Non-Pulmonary Neoplasm Risk: A Review of Epidemiologic Evidence. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:10466. [PMID: 34639764 PMCID: PMC8508162 DOI: 10.3390/ijerph181910466] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/29/2021] [Accepted: 09/29/2021] [Indexed: 12/01/2022]
Abstract
Although Radon (Rn) is a known agent for lung cancer, the link between Rn exposure and other non-pulmonary neoplasms remains unclear. The aim of this review is to investigate the role of Rn in the development of tumors other than lung cancer in both occupational and environmental exposure. Particularly, our attention has been focused on leukemia and tumors related to brain and central nervous system (CNS), skin, stomach, kidney, and breast. The epidemiologic literature has been systematically reviewed focusing on workers, general population, and pediatric population. A weak increase in leukemia risk due to Rn exposure was found, but bias and confounding factors cannot be ruled out. The results of studies conducted on stomach cancer are mixed, although with some prevalence for a positive association with Rn exposure. In the case of brain and CNS cancer and skin cancer, results are inconclusive, while no association was found for breast and kidney cancers. Overall, the available evidence does not support a conclusion that a causal association has been established between Rn exposure and the risk of other non-pulmonary neoplasms mainly due to the limited number and heterogeneity of existing studies. To confirm this result, a statistical analysis should be necessary, even if it is now not applicable for the few studies available.
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Affiliation(s)
- Paola Mozzoni
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy; (P.M.); (S.P.); (M.C.); (S.R.)
- Centre for Research in Toxicology (CERT), University of Parma, Via A. Gramsci 14, 43126 Parma, Italy
| | - Silvana Pinelli
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy; (P.M.); (S.P.); (M.C.); (S.R.)
| | - Massimo Corradi
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy; (P.M.); (S.P.); (M.C.); (S.R.)
- Centre for Research in Toxicology (CERT), University of Parma, Via A. Gramsci 14, 43126 Parma, Italy
| | - Silvia Ranzieri
- Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy; (P.M.); (S.P.); (M.C.); (S.R.)
| | - Delia Cavallo
- INAIL Research, Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, Via Fontana Candida 1, 00078 Monte Porzio Catone, Italy;
| | - Diana Poli
- INAIL Research, Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, Via Fontana Candida 1, 00078 Monte Porzio Catone, Italy;
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3
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Multi-scaled Monte Carlo calculation for radon-induced cellular damage in the bronchial airway epithelium. Sci Rep 2021; 11:10230. [PMID: 33986410 PMCID: PMC8119983 DOI: 10.1038/s41598-021-89689-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 04/21/2021] [Indexed: 12/19/2022] Open
Abstract
Radon is a leading cause of lung cancer in indoor public and mining workers. Inhaled radon progeny releases alpha particles, which can damage cells in the airway epithelium. The extent and complexity of cellular damage vary depending on the alpha particle’s kinetic energy and cell characteristics. We developed a framework to quantitate the cellular damage on the nanometer and micrometer scales at different intensities of exposure to radon progenies Po-218 and Po-214. Energy depositions along the tracks of alpha particles that were slowing down were simulated on a nanometer scale using the Monte Carlo code Geant4-DNA. The nano-scaled track histories in a 5 μm radius and 1 μm-thick cylindrical volume were integrated into the tracking scheme of alpha trajectories in a micron-scale bronchial epithelium segment in the user-written SNU-CDS program. Damage distribution in cellular DNA was estimated for six cell types in the epithelium. Deep-sited cell nuclei in the epithelium would have less chance of being hit, but DNA damage from a single hit would be more serious, because low-energy alpha particles of high LET would hit the nuclei. The greater damage in deep-sited nuclei was due to the 7.69 MeV alpha particles emitted from Po-214. From daily work under 1 WL of radon concentration, basal cells would respond with the highest portion of complex DSBs among the suspected progenitor cells in the most exposed regions of the lung epithelium.
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Farkas Á. Simulation of the effect of mucociliary clearance on the bronchial distribution of inhaled radon progenies and related cellular damage using a new deposition and clearance model for the lung. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2020; 59:651-661. [PMID: 32865689 PMCID: PMC7544752 DOI: 10.1007/s00411-020-00868-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/17/2020] [Indexed: 05/27/2023]
Abstract
Most of the current dosimetry models of inhaled short-lived radon decay products assume uniform activity distributions along the bronchial airways. In reality, however, both deposition and clearance patterns of inhaled radon progenies are highly inhomogeneous. Consequently, a new deposition-clearance model has been developed that accounts for such inhomogeneities and applied together with biophysical models of cell death and cell transformation. The scope of this study was to apply this model which is based on computational fluid and particle dynamics methods, in an effort to reveal the effect of mucociliary clearance on the bronchial distribution of deposited radon progenies. Furthermore, the influence of mucociliary clearance on the spatial distribution of biological damage due to alpha-decay of the deposited radon progenies was also studied. The results obtained demonstrate that both deposition and clearance of inhaled radon progenies are highly non-uniform within a human airway bifurcation unit. Due to the topology of the carinal ridge, a slow clearance zone emerged in this region, which is the location where most of the radio-aerosols deposit. In spite of the slow mucus movement in this zone, the initial degree of inhomogeneity of the activity due to the nonuniform deposition decreased by a factor of about 3 by considering the effect of mucociliary clearance. In the peak of the airway bifurcation, the computed cell death and cell transformation probabilities were lower when considering deposition and clearance simultaneously, compared to the case when only deposition was considered. However, cellular damage remained clustered.
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Affiliation(s)
- Árpád Farkas
- Environmental Physics Department, Centre for Energy Research, Konkoly-Thege M. út 29-33, 1121, Budapest, Hungary.
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Füri P, Farkas Á, Madas BG, Hofmann W, Winkler-Heil R, Kudela G, Balásházy I. The degree of inhomogeneity of the absorbed cell nucleus doses in the bronchial region of the human respiratory tract. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2020; 59:173-183. [PMID: 31587107 PMCID: PMC7012966 DOI: 10.1007/s00411-019-00814-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 09/17/2019] [Indexed: 05/27/2023]
Abstract
Inhalation of short-lived radon progeny is an important cause of lung cancer. To characterize the absorbed doses in the bronchial region of the airways due to inhaled radon progeny, mostly regional lung deposition models, like the Human Respiratory Tract Model (HRTM) of the International Commission on Radiological Protection, are used. However, in this model the site specificity of radiation burden in the airways due to deposition and fast airway clearance of radon progeny is not described. Therefore, in the present study, the Radact version of the stochastic lung model was used to quantify the cellular radiation dose distribution at airway generation level and to simulate the kinetics of the deposited radon progeny resulting from the moving mucus layer. All simulations were performed assuming an isotope ratio typical for an average dwelling, and breathing mode characteristic of a healthy adult sitting man. The study demonstrates that the cell nuclei receiving high doses are non-uniformly distributed within the bronchial airway generations. The results revealed that the maximum of the radiation burden is at the first few bronchial airway generations of the respiratory tract, where most of the lung carcinomas of former uranium miners were found. Based on the results of the present simulations, it can be stated that regional lung models may not be fully adequate to describe the radiation burden due to radon progeny. A more realistic and precise calculation of the absorbed doses from the decay of radon progeny to the lung requires deposition and clearance to be simulated by realistic models of airway generations.
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Affiliation(s)
- Péter Füri
- Environmental Physics Department, MTA Centre for Energy Research, Konkoly-Thege Miklós út 29-33, Budapest, 1121, Hungary.
| | - Árpád Farkas
- Environmental Physics Department, MTA Centre for Energy Research, Konkoly-Thege Miklós út 29-33, Budapest, 1121, Hungary
| | - Balázs G Madas
- Environmental Physics Department, MTA Centre for Energy Research, Konkoly-Thege Miklós út 29-33, Budapest, 1121, Hungary
| | - Werner Hofmann
- Department of Chemistry and Physics of Materials, University of Salzburg, Hellbrunnerstr. 34, 5020, Salzburg, Austria
| | - Renate Winkler-Heil
- Department of Chemistry and Physics of Materials, University of Salzburg, Hellbrunnerstr. 34, 5020, Salzburg, Austria
| | - Gábor Kudela
- Eötvös Loránd University, Pázmány Péter sétány 1/C, Budapest, 1117, Hungary
| | - Imre Balásházy
- Environmental Physics Department, MTA Centre for Energy Research, Konkoly-Thege Miklós út 29-33, Budapest, 1121, Hungary
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Hofmann W, Li WB, Friedland W, Miller BW, Madas B, Bardiès M, Balásházy I. Internal microdosimetry of alpha-emitting radionuclides. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2020; 59:29-62. [PMID: 31863162 PMCID: PMC7012986 DOI: 10.1007/s00411-019-00826-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 12/08/2019] [Indexed: 05/27/2023]
Abstract
At the tissue level, energy deposition in cells is determined by the microdistribution of alpha-emitting radionuclides in relation to sensitive target cells. Furthermore, the highly localized energy deposition of alpha particle tracks and the limited range of alpha particles in tissue produce a highly inhomogeneous energy deposition in traversed cell nuclei. Thus, energy deposition in cell nuclei in a given tissue is characterized by the probability of alpha particle hits and, in the case of a hit, by the energy deposited there. In classical microdosimetry, the randomness of energy deposition in cellular sites is described by a stochastic quantity, the specific energy, which approximates the macroscopic dose for a sufficiently large number of energy deposition events. Typical examples of the alpha-emitting radionuclides in internal microdosimetry are radon progeny and plutonium in the lungs, plutonium and americium in bones, and radium in targeted radionuclide therapy. Several microdosimetric approaches have been proposed to relate specific energy distributions to radiobiological effects, such as hit-related concepts, LET and track length-based models, effect-specific interpretations of specific energy distributions, such as the dual radiation action theory or the hit-size effectiveness function, and finally track structure models. Since microdosimetry characterizes only the initial step of energy deposition, microdosimetric concepts are most successful in exposure situations where biological effects are dominated by energy deposition, but not by subsequently operating biological mechanisms. Indeed, the simulation of the combined action of physical and biological factors may eventually require the application of track structure models at the nanometer scale.
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Affiliation(s)
- Werner Hofmann
- Biological Physics, Department of Chemistry and Physics of Materials, University of Salzburg, Hellbrunner Str. 34, 5020, Salzburg, Austria.
| | - Wei Bo Li
- Institute of Radiation Medicine, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764, Neuherberg, Germany.
| | - Werner Friedland
- Institute of Radiation Medicine, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764, Neuherberg, Germany
| | - Brian W Miller
- Department of Radiation Oncology, School of Medicine, University of Colorado, Aurora, CO, 80045, USA
- College of Optical Sciences, University of Arizona, Tucson, AZ, 85721, USA
| | - Balázs Madas
- Environmental Physics Department, MTA Centre for Energy Research, Budapest, Hungary
| | - Manuel Bardiès
- Centre de Recherches en Cancérologie de Toulouse, UMR 1037, INSERM Université Paul Sabatier, Toulouse, France
| | - Imre Balásházy
- Environmental Physics Department, MTA Centre for Energy Research, Budapest, Hungary
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Rühm W, Fantuzzi E, Harrison R, Schuhmacher H, Vanhavere F, Alves J, Bottollier Depois JF, Fattibene P, Knežević Ž, Lopez MA, Mayer S, Miljanić S, Neumaier S, Olko P, Stadtmann H, Tanner R, Woda C. EURADOS strategic research agenda: vision for dosimetry of ionising radiation. RADIATION PROTECTION DOSIMETRY 2016; 168:223-34. [PMID: 25752758 PMCID: PMC4884873 DOI: 10.1093/rpd/ncv018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/05/2015] [Accepted: 02/06/2015] [Indexed: 05/04/2023]
Abstract
Since autumn 2012, the European Radiation Dosimetry Group (EURADOS) has been developing its Strategic Research Agenda (SRA), which is intended to contribute to the identification of future research needs in radiation dosimetry in Europe. The present article summarises-based on input from EURADOS Working Groups (WGs) and Voting Members-five visions in dosimetry and defines key issues in dosimetry research that are considered important for the next decades. The five visions include scientific developments required towards (a) updated fundamental dose concepts and quantities, (b) improved radiation risk estimates deduced from epidemiological cohorts, (c) efficient dose assessment for radiological emergencies, (d) integrated personalised dosimetry in medical applications and (e) improved radiation protection of workers and the public. The SRA of EURADOS will be used as a guideline for future activities of the EURADOS WGs. A detailed version of the SRA can be downloaded as a EURADOS report from the EURADOS website (www.eurados.org).
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Affiliation(s)
- W Rühm
- Helmholtz Center Munich, Institute of Radiation Protection, Neuherberg, Germany
| | - E Fantuzzi
- Radiation Protection Institute, ENEA, Bologna, Italy
| | | | - H Schuhmacher
- Physikalisch Technische Bundesanstalt (PTB), Braunschweig, Germany
| | - F Vanhavere
- Belgian Nuclear Research Centre (SCK-CEN), Mol, Belgium
| | - J Alves
- Instituto Superior Técnico (IST), CTN, Lisboa, Portugal
| | - J F Bottollier Depois
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Fontenay-aux-Roses Cedex, France
| | - P Fattibene
- Istituto Superiore di Sanità (ISS), Rome, Italy
| | - Ž Knežević
- Ruđer Bošković Institute (RBI), Zagreb, Croatia
| | - M A Lopez
- Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain
| | - S Mayer
- Paul Scherer Institut (PSI), Villigen, Switzerland
| | - S Miljanić
- Ruđer Bošković Institute (RBI), Zagreb, Croatia
| | - S Neumaier
- Physikalisch Technische Bundesanstalt (PTB), Braunschweig, Germany
| | - P Olko
- Instytut Fizyki Jądrowej (IFJ), Krakow, Poland
| | - H Stadtmann
- Seibersdorf Labor GmbH, Seibersdorf, Austria
| | - R Tanner
- Public Health England, Chilton, Didcot, UK
| | - C Woda
- Helmholtz Center Munich, Institute of Radiation Protection, Neuherberg, Germany
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8
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Stevens DL, Bradley S, Goodhead DT, Hill MA. The Influence of Dose Rate on the Induction of Chromosome Aberrations and Gene Mutation after Exposure of Plateau Phase V79-4 Cells with High-LET Alpha Particles. Radiat Res 2014; 182:331-7. [DOI: 10.1667/rr13746.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Robertson A, Allen J, Laney R, Curnow A. The cellular and molecular carcinogenic effects of radon exposure: a review. Int J Mol Sci 2013; 14:14024-63. [PMID: 23880854 PMCID: PMC3742230 DOI: 10.3390/ijms140714024] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 06/14/2013] [Accepted: 06/17/2013] [Indexed: 02/06/2023] Open
Abstract
Radon-222 is a naturally occurring radioactive gas that is responsible for approximately half of the human annual background radiation exposure globally. Chronic exposure to radon and its decay products is estimated to be the second leading cause of lung cancer behind smoking, and links to other forms of neoplasms have been postulated. Ionizing radiation emitted during the radioactive decay of radon and its progeny can induce a variety of cytogenetic effects that can be biologically damaging and result in an increased risk of carcinogenesis. Suggested effects produced as a result of alpha particle exposure from radon include mutations, chromosome aberrations, generation of reactive oxygen species, modification of the cell cycle, up or down regulation of cytokines and the increased production of proteins associated with cell-cycle regulation and carcinogenesis. A number of potential biomarkers of exposure, including translocations at codon 249 of TP53 in addition to HPRT mutations, have been suggested although, in conclusion, the evidence for such hotspots is insufficient. There is also substantial evidence of bystander effects, which may provide complications when calculating risk estimates as a result of exposure, particularly at low doses where cellular responses often appear to deviate from the linear, no-threshold hypothesis. At low doses, effects may also be dependent on cellular conditions as opposed to dose. The cellular and molecular carcinogenic effects of radon exposure have been observed to be both numerous and complex and the elevated chronic exposure of man may therefore pose a significant public health risk that may extend beyond the association with lung carcinogenesis.
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Affiliation(s)
- Aaron Robertson
- Clinical Photobiology, European Centre for Environment and Human Health, University of Exeter Medical School, University of Exeter, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall TR1 3HD, UK; E-Mails: (J.A.); (A.C.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +44-1872-256-432; Fax: +44-1872-256-497
| | - James Allen
- Clinical Photobiology, European Centre for Environment and Human Health, University of Exeter Medical School, University of Exeter, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall TR1 3HD, UK; E-Mails: (J.A.); (A.C.)
| | - Robin Laney
- Clinical Oncology, Sunrise Centre, Royal Cornwall Hospital, Truro, Cornwall TR1 3LJ, UK; E-Mail:
| | - Alison Curnow
- Clinical Photobiology, European Centre for Environment and Human Health, University of Exeter Medical School, University of Exeter, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall TR1 3HD, UK; E-Mails: (J.A.); (A.C.)
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10
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Friedl AA, Rühm W. 50 years of Radiation and Environmental Biophysics: what were the hallmark papers? RADIATION AND ENVIRONMENTAL BIOPHYSICS 2013; 52:171-174. [PMID: 23532414 DOI: 10.1007/s00411-013-0466-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 03/11/2013] [Indexed: 06/02/2023]
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11
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Szőke I, Farkas A, Balásházy I, Hofmann W, Madas BG, Szőke R. 3D-modelling of radon-induced cellular radiobiological effects in bronchial airway bifurcations: direct versus bystander effects. Int J Radiat Biol 2012; 88:477-92. [PMID: 22420832 DOI: 10.3109/09553002.2012.676229] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
PURPOSE The primary objective of this paper was to investigate the distribution of radiation doses and the related biological responses in cells of a central airway bifurcation of the human lung of a hypothetical worker of the New Mexico uranium mines during approximately 12 hours of exposure to short-lived radon progenies. MATERIALS AND METHODS State-of-the-art computational modelling techniques were applied to simulate the relevant biophysical and biological processes in a central human airway bifurcation. RESULTS The non-uniform deposition pattern of inhaled radon daughters caused a non-uniform distribution of energy deposition among cells, and of related cell inactivation and cell transformation probabilities. When damage propagation via bystander signalling was assessed, it produced more cell killing and cell transformation events than did direct effects. If bystander signalling was considered, variations of the average probabilities of cell killing and cell transformation were supra-linear over time. CONCLUSIONS Our results are very sensitive to the radiobiological parameters, derived from in vitro experiments (e.g., range of bystander signalling), applied in this work and suggest that these parameters may not be directly applicable to realistic three-dimensional (3D) epithelium models.
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Affiliation(s)
- István Szőke
- Centre for Energy Research, Hungarian Academy of Sciences, Budapest, Hungary.
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12
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Madas BG, Balásházy I. Mutation induction by inhaled radon progeny modeled at the tissue level. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2011; 50:553-570. [PMID: 21894440 DOI: 10.1007/s00411-011-0382-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 08/12/2011] [Indexed: 05/27/2023]
Abstract
The observable responses of living systems to ionizing radiation depend on the level of biological organization studied. Understanding the relationships between the responses characteristic of the different levels of organization is of crucial importance. The main objective of the present study is to investigate how some cellular effects of radiation manifest at the tissue level by modeling mutation induction due to chronic exposure to inhaled radon progeny. For this purpose, a mathematical model of the bronchial epithelium was elaborated to quantify cell nucleus hits and cell doses. Mutagenesis was modeled considering endogenous as well as radiation-induced DNA damages and cell cycle shortening due to cell inactivation. The model parameters describing the cellular effects of radiation are obtained from experimental data. Cell nucleus hits, cell doses, and mutation induction were computed for the activity hot spots of the large bronchi at different exposures. Results demonstrate that the mutagenic effect of densely ionizing radiation is dominated by cell cycle shortening due to cell inactivation and not by DNA damages. This suggests that radiation burdens of non-progenitor cells play a significant role in mutagenesis in case of protracted exposures to densely ionizing radiation. Mutation rate as a function of dose rate exhibits a convex shape below a threshold. This threshold indicates the exhaustion of the tissue regeneration capacity of local progenitor cells. It is suggested that progenitor cell hyperplasia occurs beyond the threshold dose rate, giving a possible explanation of the inverse dose-rate effect observed in the epidemiology of lung cancer among uranium miners.
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Affiliation(s)
- Balázs G Madas
- Hungarian Academy of Sciences KFKI Atomic Energy Research Institute, Budapest, Hungary.
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