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Madas BG, Boei J, Fenske N, Hofmann W, Mezquita L. Effects of spatial variation in dose delivery: what can we learn from radon-related lung cancer studies? Radiat Environ Biophys 2022; 61:561-577. [PMID: 36208308 PMCID: PMC9630403 DOI: 10.1007/s00411-022-00998-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 09/28/2022] [Indexed: 05/14/2023]
Abstract
Exposure to radon progeny results in heterogeneous dose distributions in many different spatial scales. The aim of this review is to provide an overview on the state of the art in epidemiology, clinical observations, cell biology, dosimetry, and modelling related to radon exposure and its association with lung cancer, along with priorities for future research. Particular attention is paid on the effects of spatial variation in dose delivery within the organs, a factor not considered in radiation protection. It is concluded that a multidisciplinary approach is required to improve risk assessment and mechanistic understanding of carcinogenesis related to radon exposure. To achieve these goals, important steps would be to clarify whether radon can cause other diseases than lung cancer, and to investigate radon-related health risks in children or persons at young ages. Also, a better understanding of the combined effects of radon and smoking is needed, which can be achieved by integrating epidemiological, clinical, pathological, and molecular oncology data to obtain a radon-associated signature. While in vitro models derived from primary human bronchial epithelial cells can help to identify new and corroborate existing biomarkers, they also allow to study the effects of heterogeneous dose distributions including the effects of locally high doses. These novel approaches can provide valuable input and validation data for mathematical models for risk assessment. These models can be applied to quantitatively translate the knowledge obtained from radon exposure to other exposures resulting in heterogeneous dose distributions within an organ to support radiation protection in general.
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Affiliation(s)
- Balázs G Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary.
| | - Jan Boei
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Nora Fenske
- Federal Office for Radiation Protection, Munich (Neuherberg), Germany
| | - Werner Hofmann
- Biological Physics, Department of Chemistry and Physics of Materials, University of Salzburg, Salzburg, Austria
| | - Laura Mezquita
- Medical Oncology Department, Hospital Clinic of Barcelona, Barcelona, Spain
- Laboratory of Translational Genomic and Targeted Therapies in Solid Tumors, IDIBAPS, Barcelona, Spain
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2
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Madas BG, Wojcik A. The 2020 MELODI workshop on the effects of spatial and temporal variation in dose delivery. Radiat Environ Biophys 2022; 61:479-483. [PMID: 36280614 PMCID: PMC9592538 DOI: 10.1007/s00411-022-01002-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
A key activity of MELODI is to organise annual European meetings where scientific results and future directions and strategies of relevant research are discussed. The annual meetings, previously organised solely under the auspices of MELODI are, since 2016, jointly organised by the European platforms and referred to as European Radiation Protection Weeks (ERPW). In addition to ERPW meetings, MELODI organises and finances annual workshops dedicated to specific topics. Outputs and recommendations from the meetings are published as review articles. The 2020 workshop focussed on one of the cross cutting topics: the effects of spatial and temporal variation in dose delivery on disease risk. The current issue of REBS includes five review articles from the workshop on the effects of spatial and temporal variation in dose delivery and this editorial is a short summary of their content.
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Affiliation(s)
- Balázs G. Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Andrzej Wojcik
- Centre for Radiation Protection Research, MBW Department, Stockholm University, Svante Arrhenius väg 20C, 106 91 Stockholm, Sweden
- Institute for Biology, Jan Kochanowski University, Kielce, Poland
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Polgár S, Schofield PN, Madas BG. Datasets of in vitro clonogenic assays showing low dose hyper-radiosensitivity and induced radioresistance. Sci Data 2022; 9:555. [PMID: 36075916 PMCID: PMC9458642 DOI: 10.1038/s41597-022-01653-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 08/19/2022] [Indexed: 11/19/2022] Open
Abstract
Low dose hyper-radiosensitivity and induced radioresistance are primarily observed in surviving fractions of cell populations exposed to ionizing radiation, plotted as the function of absorbed dose. Several biophysical models have been developed to quantitatively describe these phenomena. However, there is a lack of raw, openly available experimental data to support the development and validation of quantitative models. The aim of this study was to set up a database of experimental data from the public literature. Using Google Scholar search, 46 publications with 101 datasets on the dose-dependence of surviving fractions, with clear evidence of low dose hyper-radiosensitivity, were identified. Surviving fractions, their uncertainties, and the corresponding absorbed doses were digitized from graphs of the publications. The characteristics of the cell line and the irradiation were also recorded, along with the parameters of the linear-quadratic model and/or the induced repair model if they were provided. The database is available in STOREDB, and can be used for meta-analysis, for comparison with new experiments, and for development and validation of biophysical models. Measurement(s) | surviving fraction of cells | Technology Type(s) | optical microscopy | Factor Type(s) | absorbed dose | Sample Characteristic - Organism | Homo sapiens • Chinese hamster • Rattus sp. | Sample Characteristic - Environment | cell culture |
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Affiliation(s)
- Szabolcs Polgár
- Doctoral School of Physics, ELTE Eötvös Loránd University, Budapest, Hungary.,Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Paul N Schofield
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Balázs G Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary. .,Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budapest, Hungary.
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Darquenne C, Borojeni AA, Colebank MJ, Forest MG, Madas BG, Tawhai M, Jiang Y. Aerosol Transport Modeling: The Key Link Between Lung Infections of Individuals and Populations. Front Physiol 2022; 13:923945. [PMID: 35795643 PMCID: PMC9251577 DOI: 10.3389/fphys.2022.923945] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 05/24/2022] [Indexed: 12/18/2022] Open
Abstract
The recent COVID-19 pandemic has propelled the field of aerosol science to the forefront, particularly the central role of virus-laden respiratory droplets and aerosols. The pandemic has also highlighted the critical need, and value for, an information bridge between epidemiological models (that inform policymakers to develop public health responses) and within-host models (that inform the public and health care providers how individuals develop respiratory infections). Here, we review existing data and models of generation of respiratory droplets and aerosols, their exhalation and inhalation, and the fate of infectious droplet transport and deposition throughout the respiratory tract. We then articulate how aerosol transport modeling can serve as a bridge between and guide calibration of within-host and epidemiological models, forming a comprehensive tool to formulate and test hypotheses about respiratory tract exposure and infection within and between individuals.
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Affiliation(s)
- Chantal Darquenne
- Department of Medicine, University of California, San Diego, San Diego, CA, United States
- *Correspondence: Chantal Darquenne,
| | - Azadeh A.T. Borojeni
- Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Mitchel J. Colebank
- Edwards Lifesciences Foundation Cardiovascular Innovation and Research Center and Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, United States
| | - M. Gregory Forest
- Departments of Mathematics, Applied Physical Sciences, and Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Balázs G. Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Merryn Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Yi Jiang
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, United States
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Nagy A, Horváth A, Farkas Á, Füri P, Erdélyi T, Madas BG, Czitrovszky A, Merkely B, Szabó A, Ungvári Z, Müller V. Modeling of nursing care-associated airborne transmission of SARS-CoV-2 in a real-world hospital setting. GeroScience 2022; 44:585-595. [PMID: 34985588 PMCID: PMC8729098 DOI: 10.1007/s11357-021-00512-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/29/2021] [Indexed: 11/28/2022] Open
Abstract
Respiratory transmission of SARS-CoV-2 from one older patient to another by airborne mechanisms in hospital and nursing home settings represents an important health challenge during the COVID-19 pandemic. However, the factors that influence the concentration of respiratory droplets and aerosols that potentially contribute to hospital- and nursing care-associated transmission of SARS-CoV-2 are not well understood. To assess the effect of health care professional (HCP) and patient activity on size and concentration of airborne particles, an optical particle counter was placed (for 24 h) in the head position of an empty bed in the hospital room of a patient admitted from the nursing home with confirmed COVID-19. The type and duration of the activity, as well as the number of HCPs providing patient care, were recorded. Concentration changes associated with specific activities were determined, and airway deposition modeling was performed using these data. Thirty-one activities were recorded, and six representative ones were selected for deposition modeling, including patient's activities (coughing, movements, etc.), diagnostic and therapeutic interventions (e.g., diagnostic tests and drug administration), as well as nursing patient care (e.g., bedding and hygiene). The increase in particle concentration of all sizes was sensitive to the type of activity. Increases in supermicron particle concentration were associated with the number of HCPs (r = 0.66; p < 0.05) and the duration of activity (r = 0.82; p < 0.05), while submicron particles increased with all activities, mainly during the daytime. Based on simulations, the number of particles deposited in unit time was the highest in the acinar region, while deposition density rate (number/cm2/min) was the highest in the upper airways. In conclusion, even short periods of HCP-patient interaction and minimal patient activity in a hospital room or nursing home bedroom may significantly increase the concentration of submicron particles mainly depositing in the acinar regions, while mainly nursing activities increase the concentration of supermicron particles depositing in larger airways of the adjacent bed patient. Our data emphasize the need for effective interventions to limit hospital- and nursing care-associated transmission of SARS-CoV-2 and other respiratory pathogens (including viral pathogens, such as rhinoviruses, respiratory syncytial virus, influenza virus, parainfluenza virus and adenoviruses, and bacterial and fungal pathogens).
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Affiliation(s)
- Attila Nagy
- Department of Applied and Nonlinear Optics, Wigner Research Centre for Physics, Konkoly-Thege Miklós st. 29-33, Budapest, Hungary
| | - Alpár Horváth
- Department of Pulmonology, Semmelweis University, Budapest, Hungary
| | - Árpád Farkas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Péter Füri
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Tamás Erdélyi
- Department of Pulmonology, Semmelweis University, Budapest, Hungary
| | - Balázs G Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Aladár Czitrovszky
- Department of Applied and Nonlinear Optics, Wigner Research Centre for Physics, Konkoly-Thege Miklós st. 29-33, Budapest, Hungary.,Envi-Tech Ltd, Budapest, Hungary
| | - Béla Merkely
- Heart and Vascular Centre, Semmelweis University, Budapest, Hungary
| | - Attila Szabó
- 1st Department of Pediatrics Semmelweis University, Budapest, Hungary.,Clinical Center, Semmelweis University, Budapest, Hungary
| | - Zoltán Ungvári
- Vascular Cognitive Impairment and Neurodegeneration Program, Oklahoma Center for Geroscience and Healthy Brain Aging, Department of Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 731042, USA.,Peggy and Charles Stephenson Cancer Center, Oklahoma City, OK, 73104, USA.,Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.,International Training Program in Geroscience, Doctoral School of Basic and Translational Medicine/Department of Public Health, Semmelweis University, Budapest, Hungary
| | - Veronika Müller
- Department of Pulmonology, Semmelweis University, Budapest, Hungary
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Rabaeh KA, Eyadeh MM, Hailat TF, Madas BG, Aldweri FM, Almomani AM, Awad SI. Improvement on the performance of chemically cross-linked fricke methylthymol-blue radiochromic gel dosimeter by addition of dimethyl sulfoxide. RADIAT MEAS 2021. [DOI: 10.1016/j.radmeas.2021.106540] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Madas BG, Füri P, Farkas Á, Nagy A, Czitrovszky A, Balásházy I, Schay GG, Horváth A. Deposition distribution of the new coronavirus (SARS-CoV-2) in the human airways upon exposure to cough-generated droplets and aerosol particles. Sci Rep 2020; 10:22430. [PMID: 33384436 PMCID: PMC7775446 DOI: 10.1038/s41598-020-79985-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 12/15/2020] [Indexed: 01/09/2023] Open
Abstract
The new coronavirus disease 2019 (COVID-19) has been emerged as a rapidly spreading pandemic. The disease is thought to spread mainly from person-to-person through respiratory droplets produced when an infected person coughs, sneezes, or talks. The pathogen of COVID-19 is the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It infects the cells binding to the angiotensin-converting enzyme 2 receptor (ACE2) which is expressed by cells throughout the airways as targets for cellular entry. Although the majority of persons infected with SARS-CoV-2 experience symptoms of mild upper respiratory tract infection, in some people infections of the acinar airways result in severe, potentially fatal pneumonia. However, the induction of COVID-19 pneumonia requires that SARS-CoV-2 reaches the acinar airways. While huge efforts have been made to understand the spread of the disease as well as the pathogenesis following cellular entry, much less attention is paid to how SARS-CoV-2 from the environment reach the receptors of the target cells. The aim of the present study is to characterize the deposition distribution of SARS-CoV-2 in the airways upon exposure to cough-generated droplets and aerosol particles. For this purpose, the Stochastic Lung Deposition Model has been applied. Particle size distribution, breathing parameters supposing normal breathing through the nose, and viral loads were taken from the literature. We found that the probability of direct infection of the acinar airways due to inhalation of particles emitted by a bystander cough is very low. As the number of viruses deposited in the extrathoracic airways is about 7 times higher than in the acinar airways, we concluded that in most cases COVID-19 pneumonia must be preceded by SARS-CoV-2 infection of the upper airways. Our results suggest that without the enhancement of viral load in the upper airways, COVID-19 would be much less dangerous. The period between the onset of initial symptoms and the potential clinical deterioration could provide an opportunity for prevention of pneumonia by blocking or significantly reducing the transport of viruses towards the acinar airways. Therefore, even non-specific treatment forms like disinfection of the throat and nasal and oral mucosa may effectively keep the viral load of the upper airways low enough to avoid or prolong the progression of the disease. In addition, using a tissue or cloth in order to absorb droplets and aerosol particles emitted by own coughs of infected patients before re-inhalation is highly recommended even if they are alone in quarantine.
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Affiliation(s)
- Balázs G Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary.
| | - Péter Füri
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Árpád Farkas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Attila Nagy
- Laser Applications and Optical Measurement Techniques, Applied and Nonlinear Optics, Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Budapest, Hungary
| | - Aladár Czitrovszky
- Laser Applications and Optical Measurement Techniques, Applied and Nonlinear Optics, Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Budapest, Hungary.,Envi-Tech Ltd., Budapest, Hungary
| | - Imre Balásházy
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Gusztáv G Schay
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary
| | - Alpár Horváth
- Department of Pulmonology, County Institute of Pulmonology, Törökbálint, Hungary.,Medical Department, Chiesi Hungary Ltd., Budapest, Hungary
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Mothersill CE, Oughton DH, Schofield PN, Abend M, Adam-Guillermin C, Ariyoshi K, Beresford NA, Bonisoli-Alquati A, Cohen J, Dubrova Y, Geras’kin SA, Hevrøy TH, Higley KA, Horemans N, Jha AN, Kapustka LA, Kiang JG, Madas BG, Powathil G, Sarapultseva EI, Seymour CB, Vo NTK, Wood MD. From tangled banks to toxic bunnies; a reflection on the issues involved in developing an ecosystem approach for environmental radiation protection. Int J Radiat Biol 2020; 98:1185-1200. [DOI: 10.1080/09553002.2020.1793022] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | | | - Paul N. Schofield
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Michael Abend
- Bundeswehr Institute of Radiobiology, Munich, Germany
| | | | - Kentaro Ariyoshi
- Integrated Center for Science and Humanities, Fukushima Medical University, Fukushima City, Japan
| | | | | | - Jason Cohen
- Department of Biology and Department of Physics and Astronomy, McMaster University, Hamilton, Canada
| | - Yuri Dubrova
- Department of Genetics, University of Leicester, Leicester, UK
| | | | | | - Kathryn A. Higley
- School of Nuclear Science and Engineering, Oregon State University, Corvallis, OR, USA
| | - Nele Horemans
- Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Awadhesh N. Jha
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK
| | | | - Juliann G. Kiang
- Armed Forces Radiobiology Research Institute, Uniformed services University of the Health Sciences, Bethesda, MD, USA
| | - Balázs G. Madas
- Environmental Physics Department, Centre for Energy Research, Budapest, Hungary
| | - Gibin Powathil
- Department of Mathematics, Computational Foundry, Swansea University, Swansea, UK
| | | | | | - Nguyen T. K. Vo
- Department of Biology and Department of Physics and Astronomy, McMaster University, Hamilton, Canada
| | - Michael D. Wood
- School of Science, Engineering & Environment, University of Salford, Salford, UK
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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. Radiat Environ Biophys 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Madas BG, Drozsdik EJ. COMPUTATIONAL MODELING OF LOW DOSE HYPER-RADIOSENSITIVITY AND INDUCED RADIORESISTANCE APPLYING THE PRINCIPLE OF MINIMUM MUTATION LOAD. Radiat Prot Dosimetry 2019; 183:147-150. [PMID: 30535421 DOI: 10.1093/rpd/ncy227] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Low dose hyper-radiosensitivity (HRS) and induced radioresistance (IRR) can be observed in the dose dependence of survival of many different cell lines. While surviving fraction decreases exponentially in a large-scale view, a local minimum can be found at around 0.5 Gy. Although, there is evidence that the regulation of apoptosis and DNA repair are involved in HRS and IRR, the fundamental causes of the phenomena remain unclear. The objective of the present study is to test whether the principle of minimum mutation load can provide an explanation for both low dose HRS and IRR. For this purpose, a mathematical model was elaborated considering radiation induced mutagenic DNA lesions as well as cell divisions as sources of mutations. It was presumed that cell number is in dynamic equilibrium in the tissue, the number of mutations follows Poisson distribution, and its average is proportional to absorbed dose. For each value of absorbed dose, the minimum number of mutations were computed for different surviving fractions. Then that surviving fraction was plotted that results in the lowest number of mutations. One minimum or multiple minima can be seen in the dose dependence of surviving fractions with reasonable values for the model parameters: spontaneous and radiation induced mutation rate. Although the mechanisms remain unclear, the principle of minimum mutation load provides a potential explanation for low dose HRS and IRR and for the fact that they are mostly observed in cell lines with defected DNA repair.
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Affiliation(s)
- Balázs G Madas
- Radiation Biophysics Group, Environmental Physics Department, MTA Centre for Energy Research, Budapest, Hungary
| | - Emese J Drozsdik
- Radiation Biophysics Group, Environmental Physics Department, MTA Centre for Energy Research, Budapest, Hungary
- Department of Biological Physics, Doctoral School of Physics, ELTE Eötvös Loránd University, Budapest, Hungary
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Madas BG, Schofield PN. SURVEY ON DATA MANAGEMENT IN RADIATION PROTECTION RESEARCH. Radiat Prot Dosimetry 2019; 183:233-236. [PMID: 30534952 DOI: 10.1093/rpd/ncy250] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 11/15/2018] [Indexed: 06/09/2023]
Abstract
The importance of datasharing is of increasing concern to funding bodies and institutions. With some prescience, the radiobiology community has established datasharing infrastructures over the last two decades, including STORE; however, the utilization of these databases is disappointing. The aim of the present study was to identify the current state of datasharing amongst researchers in radiation protection, and to identify barriers to effective sharing. An electronic survey was prepared, including questions on post-publication data provision, institutional, funding agency, and journal policies, awareness of datasharing infrastructures, attitudinal barriers and technical support. The survey was sent to the members of a mailing list maintained by the EC funded CONCERT project. Responses identified that the radiation protection community shared similar concerns to other groups canvassed in earlier studies; the perceived negative impact of datasharing on competitiveness, career development and reputation, along with concern about the costs of data management. More surprising was the lack of awareness of existing datasharing platforms. We find that there is a clear need for education and training in data management and for a significant programme of improving awareness of Open Data issues.
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Affiliation(s)
- Balázs G Madas
- Radiation Biophysics Group, Environmental Physics Department, MTA Centre for Energy Research, Konkoly-Thege Miklós út 29-33., Budapest, Hungary
| | - Paul N Schofield
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, United Kingdom
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12
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Drozsdik EJ, Madas BG. QUANTITATIVE ANALYSIS OF THE POTENTIAL ROLE OF BASAL CELL HYPERPLASIA IN THE RELATIONSHIP BETWEEN CLONAL EXPANSION AND RADON CONCENTRATION. Radiat Prot Dosimetry 2019; 183:237-241. [PMID: 30668805 DOI: 10.1093/rpd/ncy302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 12/24/2018] [Indexed: 05/27/2023]
Abstract
Applying the two-stage clonal expansion model to epidemiology of lung cancer among uranium miners, it has been revealed that radon acts as a promoting agent facilitating the clonal expansion of already mutated cells. Clonal expansion rate increases non-linearly by radon concentration showing a plateau above a given exposure rate. The underlying mechanisms remain unclear. Earlier we proposed that progenitor cell hyperplasia may be induced upon chronic radon exposure. The objective of the present study is to test whether the induction of hyperplasia may provide a quantitative explanation for the plateau in clonal expansion rate. For this purpose, computational epithelium models were prepared with different number of basal cells. Cell nucleus hits were computed by an own-developed Monte-Carlo code. Surviving fractions were estimated based on the number of cell nucleus hits. Cell division rate was computed supposing equilibrium between cell death and cell division. It was also supposed that clonal expansion rate is proportional to cell division rate, and therefore the relative increase in cell division rate and clonal expansion rate are the same functions of exposure rate. While the simulation results highly depend on model parameters with high uncertainty, a parameter set has been found resulting in a cell division rate-exposure rate relationship corresponding to the plateau in clonal expansion rate. Due to the high uncertainty of the applied parameters, however, further studies are required to decide whether the induction of hyperplasia is responsible for the non-linear increase in clonal expansion rate or not. Nevertheless, the present study exemplifies how computational modelling can contribute to the integration of observational and experimental radiation protection research.
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Affiliation(s)
- Emese J Drozsdik
- Department of Biological Physics, Doctoral School of Physics, ELTE Eötvös Loránd University, Budapest, Hungary
- Radiation Biophysics Group, Environmental Physics Department, MTA Centre for Energy Research, Budapest, Hungary
| | - Balázs G Madas
- Radiation Biophysics Group, Environmental Physics Department, MTA Centre for Energy Research, Budapest, Hungary
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Madas BG, Drozsdik EJ. Effects of mucus thickness and goblet cell hyperplasia on microdosimetric quantities characterizing the bronchial epithelium upon radon exposure. Int J Radiat Biol 2018; 94:967-974. [PMID: 30265181 DOI: 10.1080/09553002.2018.1511931] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
PURPOSE The most exposed tissue upon radon exposure is the bronchial epithelium where goblet cells serve as responsive and adaptable front-line defenders. They can rapidly produce a vast amount of mucus, and can change in number, in response to airway insults. The objective of the present study is to quantify the effects of mucus discharge and goblet cell hyperplasia on the microscopic dose consequences of macroscopic radon exposures. METHODS For this purpose, computational models of the bronchial epithelium and alpha-particle transport have been prepared and applied to quantify the hits received and doses absorbed by cell nuclei in case of different mucus thicknesses and goblet cell number. RESULTS AND CONCLUSIONS Both mucus discharge and induction of goblet cell hyperplasia reduce radiation burden at the cellular level, and as such they both can be considered as radioadaptive responses to radon exposure. As compared to basal cell hyperplasia, goblet cell hyperplasia is more effective in reducing the microscopic dose consequences of a given macroscopic exposure. Such changes in exposure geometry highlight the need for improvements in the application of biokinetic and dosimetry models for incorporated radionuclides as well as the dose and dose rate effectiveness factor.
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Affiliation(s)
| | - Emese J Drozsdik
- a MTA Centre for Energy Research , Budapest , Hungary.,b Doctoral School of Physics , ELTE Eötvös Loránd University , Budapest , Hungary
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Kreuzer M, Auvinen A, Cardis E, Durante M, Harms-Ringdahl M, Jourdain JR, Madas BG, Ottolenghi A, Pazzaglia S, Prise KM, Quintens R, Sabatier L, Bouffler S. Multidisciplinary European Low Dose Initiative (MELODI): strategic research agenda for low dose radiation risk research. Radiat Environ Biophys 2018; 57:5-15. [PMID: 29247291 PMCID: PMC5816101 DOI: 10.1007/s00411-017-0726-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/10/2017] [Indexed: 05/05/2023]
Abstract
MELODI (Multidisciplinary European Low Dose Initiative) is a European radiation protection research platform with focus on research on health risks after exposure to low-dose ionising radiation. It was founded in 2010 and currently includes 44 members from 18 countries. A major activity of MELODI is the continuous development of a long-term European Strategic Research Agenda (SRA) on low-dose risk for radiation protection. The SRA is intended to identify priorities for national and European radiation protection research programs as a basis for the preparation of competitive calls at the European level. Among those key priorities is the improvement of health risk estimates for exposures close to the dose limits for workers and to reference levels for the population in emergency situations. Another activity of MELODI is to ensure the availability of European key infrastructures for research activities, and the long-term maintenance of competences in radiation research via an integrated European approach for training and education. The MELODI SRA identifies three key research topics in low dose or low dose-rate radiation risk research: (1) dose and dose rate dependence of cancer risk, (2) radiation-induced non-cancer effects and (3) individual radiation sensitivity. The research required to improve the evidence base for each of the three key topics relates to three research lines: (1) research to improve understanding of the mechanisms contributing to radiogenic diseases, (2) epidemiological research to improve health risk evaluation of radiation exposure and (3) research to address the effects and risks associated with internal exposures, differing radiation qualities and inhomogeneous exposures. The full SRA and associated documents can be downloaded from the MELODI website ( http://www.melodi-online.eu/sra.html ).
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Affiliation(s)
- M Kreuzer
- Department of Radiation Protection and Health, Federal Office for Radiation Protection, BfS, Neuherberg, Germany.
| | - A Auvinen
- University of Tampere, Tampere, Finland
- STUK, Helsinki, Finland
| | - E Cardis
- ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain
| | - M Durante
- Institute for Fundamental Physics and Applications, TIFPA, Trento, Italy
| | - M Harms-Ringdahl
- Centre for Radiation Protection Research, Stockholm University, Stockholm, Sweden
| | - J R Jourdain
- Institute for Radiological Protection and Nuclear Safety, IRSN, Fontenay-aux-roses, France
| | - B G Madas
- Environmental Physics Department, MTA Centre for Energy Research, Budapest, Hungary
| | - A Ottolenghi
- Physics Department, University of Pavia, Pavia, Italy
| | - S Pazzaglia
- Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Rome, Italy
| | - K M Prise
- Queens University Belfast, Belfast, UK
| | - R Quintens
- Belgian Nuclear Research Centre, SCK-CEN, Mol, Belgium
| | - L Sabatier
- French Atomic Energy Commission, CEA, Paris, France
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Abstract
There is experimental and histological evidence that chronic irritation and cell death may cause hyperplasia in the exposed tissue. As the heterogeneous deposition of inhaled radon progeny results in high local doses at the peak of the bronchial bifurcations, it was proposed earlier that hyperplasia occurs in these deposition hot spots upon chronic radon exposure. The objective of the present study is to quantify how the induction of basal cell hyperplasia modulates the microdosimetric consequences of a given radon exposure. For this purpose, computational epithelium models were constructed with spherical cell nuclei of six different cell types based on histological data. Basal cell hyperplasia was modelled by epithelium models with additional basal cells and increased epithelium thickness. Microdosimetry for alpha-particles was performed by an own-developed Monte-Carlo code. Results show that the average tissue dose, and the average hit number and dose of basal cells decrease by the increase of the measure of hyperplasia. Hit and dose distribution reveal that the induction of hyperplasia may result in a basal cell pool which is shielded from alpha-radiation. It highlights that the exposure history affects the microdosimetric consequences of a present exposure, while the biological and health effects may also depend on previous exposures. The induction of hyperplasia can be considered as a radioadaptive response at the tissue level. Such an adaptation of the tissue challenges the validity of the application of the dose and dose rate effectiveness factor from a mechanistic point of view. As the location of radiosensitive target cells may change due to previous exposures, dosimetry models considering the tissue geometry characteristic of normal conditions may be inappropriate for dose estimation in case of protracted exposures. As internal exposures are frequently chronic, such changes in tissue geometry may be highly relevant for other incorporated radionuclides.
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Affiliation(s)
- Balázs G Madas
- Radiation Biophysics Group, Environmental Physics Department, Centre for Energy Research, Hungarian Academy of Sciences, 1121 Budapest, Konkoly-Thege Miklós út 29-33., Hungary
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Abstract
Investigating the health effects of low doses of ionizing radiation is considered to be one of the most important fields in radiological protection research. Although the definition of low dose given by a dose range seems to be clear, it leaves some open questions. For example, the time frame and the target volume in which absorbed dose is measured have to be defined. While dose rate is considered in the current system of radiological protection, the same cancer risk is associated with all exposures, resulting in a given amount of energy absorbed by a single target cell or distributed among all the target cells of a given organ. However, the biological effects and so the health consequences of these extreme exposure scenarios are unlikely to be the same. Due to the heterogeneous deposition of radon progeny within the lungs, heterogeneous radiation exposure becomes a practical issue in radiological protection. While the macroscopic dose is still within the low dose range, local tissue doses on the order of Grays can be reached in the most exposed parts of the bronchial airways. It can be concluded that progress in low dose research needs not only low dose but also high dose experiments where small parts of a biological sample receive doses on the order of Grays, while the average dose over the whole sample remains low. A narrow interpretation of low dose research might exclude investigations with high relevance to radiological protection. Therefore, studies important to radiological protection should be performed in the frame of low dose research even if the applied doses do not fit in the dose range used for the definition of low doses.
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Affiliation(s)
- Balázs G Madas
- *Environmental Physics Department, Centre for Energy Research, Hungarian Academy of Sciences
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Madas BG, Balásházy I. Erratum to: Mutation induction by inhaled radon progeny modeled at the tissue level. Radiat Environ Biophys 2016; 55:265-266. [PMID: 27025503 DOI: 10.1007/s00411-016-0638-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 02/02/2016] [Indexed: 06/05/2023]
Affiliation(s)
- Balázs G Madas
- Environmental Physics Department, Centre for Energy Research, Hungarian Academy of Sciences, Konkoly-Thege Miklós út 29-33, Budapest, 1121, Hungary.
| | - Imre Balásházy
- Environmental Physics Department, Centre for Energy Research, Hungarian Academy of Sciences, Konkoly-Thege Miklós út 29-33, Budapest, 1121, Hungary
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Madas BG, Varga K. Biophysical modelling of the effects of inhaled radon progeny on the bronchial epithelium for the estimation of the relationships applied in the two-stage clonal expansion model of carcinogenesis. Radiat Prot Dosimetry 2014; 159:237-41. [PMID: 24743753 DOI: 10.1093/rpd/ncu125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
There is a considerable debate between research groups applying the two-stage clonal expansion model for lung cancer risk estimation, whether radon exposure affects initiation and transformation or promotion. The aim of the present study is to quantify the effects of radon progeny on these stages with biophysical models. For this purpose, numerical models of mutation induction and clonal growth were applied in order to estimate how initiation, transformation and promotion rates depend on tissue dose rate. It was found that rates of initiation and transformation increase monotonically with dose rate, whereas effective promotion rate decreases with time but increases sublinearly with dose rate. Despite the uncertainty of results due to the lack of experimental data, present study suggests that effects of radon exposure on both mutational events and clonal growth are significant and should be considered in mechanistic models of carcinogenesis applied for analysing epidemiological data.
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Affiliation(s)
- Balázs G Madas
- Environmental Physics Department, Centre for Energy Research, Hungarian Academy of Sciences, Konkoly-Thege Miklós út 29-33, Budapest 1121, Hungary
| | - Katalin Varga
- Environmental Physics Department, Centre for Energy Research, Hungarian Academy of Sciences, Konkoly-Thege Miklós út 29-33, Budapest 1121, Hungary
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Madas BG, Balásházy I. Mutation induction by inhaled radon progeny modeled at the tissue level. Radiat Environ Biophys 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Farkas A, Hofmann W, Balásházy I, Szoke I, Madas BG, Moustafa M. Effect of site-specific bronchial radon progeny deposition on the spatial and temporal distributions of cellular responses. Radiat Environ Biophys 2011; 50:281-297. [PMID: 21327807 DOI: 10.1007/s00411-011-0357-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Accepted: 01/30/2011] [Indexed: 05/30/2023]
Abstract
Inhaled short-lived radon progenies may deposit in bronchial airways and interact with the epithelium by the emission of alpha particles. Simulation of the related radiobiological effects requires the knowledge of space and time distributions of alpha particle hits and biological endpoints. Present modelling efforts include simulation of radioaerosol deposition patterns in a central bronchial airway bifurcation, modelling of human bronchial epithelium, generation of alpha particle tracks, and computation of spatio-temporal distributions of cell nucleus hits, cell killing and cell transformation events. Simulation results indicate that the preferential radionuclide deposition at carinal ridges plays an important role in the space and time evolution of the biological events. While multiple hits are generally rare for low cumulative exposures, their probability may be quite high at the carinal ridges of the airway bifurcations. Likewise, cell killing and transformation events also occur with higher probability in this area. In the case of uniform surface activities, successive hits as well as cell killing and transformation events within a restricted area (say 0.5 mm(2)) are well separated in time. However, in the case of realistic inhomogeneous deposition, they occur more frequently within the mean cycle time of cells located at the carinal ridge even at low cumulative doses. The site-specificity of radionuclide deposition impacts not only on direct, but also on non-targeted radiobiological effects due to intercellular communication. Incorporation of present results into mechanistic models of carcinogenesis may provide useful information concerning the dose-effect relationship in the low-dose range.
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Affiliation(s)
- Arpád Farkas
- Health and Environmental Physics Department, Hungarian Academy of Sciences KFKI Atomic Energy Research Institute, Konkoly Thege M. út 29-33, 1121, Budapest, Hungary.
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Madas BG, Balásházy I, Farkas Á, Szoke I. Cellular burdens and biological effects on tissue level caused by inhaled radon progenies. Radiat Prot Dosimetry 2011; 143:253-257. [PMID: 21186213 DOI: 10.1093/rpd/ncq522] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In the case of radon exposure, the spatial distribution of deposited radioactive particles is highly inhomogeneous in the central airways. The object of this research is to investigate the consequences of this heterogeneity regarding cellular burdens in the bronchial epithelium and to study the possible biological effects at tissue level. Applying computational fluid and particle dynamics techniques, the deposition distribution of inhaled radon daughters has been determined in a bronchial airway model for 23 min of work in the New Mexico uranium mine corresponding to 0.0129 WLM exposure. A numerical epithelium model based on experimental data has been utilised in order to quantify cellular hits and doses. Finally, a carcinogenesis model considering cell death-induced cell-cycle shortening has been applied to assess the biological responses. Present computations reveal that cellular dose may reach 1.5 Gy, which is several orders of magnitude higher than tissue dose. The results are in agreement with the histological finding that the uneven deposition distribution of radon progenies may lead to inhomogeneous spatial distribution of tumours in the bronchial airways. In addition, at the macroscopic level, the relationship between cancer risk and radiation burden seems to be non-linear.
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Affiliation(s)
- B G Madas
- Health and Environmental Physics Department, Hungarian Academy of Sciences KFKI Atomic Energy Research Institute, Konkoly-Thege Miklós út 29-33, H-1121 Budapest, Hungary.
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Balásházy I, Hofmann W, Farkas Á, Madas BG. Three-Dimensional Model for Aerosol Transport and Deposition in Expanding and Contracting Alveoli. Inhal Toxicol 2008; 20:611-21. [DOI: 10.1080/08958370801915291] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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