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Chappell LJ, Rahill KM, Elgart SR. Of Men and Mice: Using Terrestrial Radiation Epidemiology Methods to Inform Analysis of Animal Models for Space Radiation Risk Assessment. Radiat Res 2023; 200:116-126. [PMID: 37212725 DOI: 10.1667/rade-22-00176.1] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 04/27/2023] [Indexed: 05/23/2023]
Abstract
Prediction of cancer risk from space radiation exposure is critical to ensure spaceflight crewmembers are adequately informed of the risks they face when accepting assignments to ambitious long-duration exploratory missions. Although epidemiological studies have assessed the effects of exposure to terrestrial radiation, no robust epidemiological studies of humans exposed to space radiation exist to support estimates of the risk from space radiation exposure. Mouse data derived from recent irradiation experiments provides valuable information to successfully develop mouse-based excess risks models for assessing relative biological effectiveness for heavy ions that can provide information to scale unique space radiation exposures so that excess risks estimated for terrestrial radiation can be adjusted for space radiation risk assessment. Bayesian analyses were used to simulate linear slopes for excess risk models with several different effect modifiers for attained age and sex. Relative biological effectiveness values for all-solid cancer mortality were calculated from the ratio of the heavy-ion linear slope to the gamma linear slope using the full posterior distribution and resulted in values that were substantially lower than what is currently applied in risk assessment. These analyses provide an opportunity to improve characterization of parameters used in the current NASA Space Cancer Risk (NSCR) model and generate new hypotheses for future animal experiments using out-bred mouse populations.
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Dynan WS, Chang PY, Sishc BJ, Elgart SR. Breaking the limit: Biological countermeasures for space radiation exposure to enable long-duration spaceflight. Life Sci Space Res (Amst) 2022; 35:1-3. [PMID: 36336355 DOI: 10.1016/j.lssr.2022.10.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Concerns over the health effects of space radiation exposure currently limit the duration of deep-space travel. Effective biological countermeasures could allow humanity to break this limit, facilitating human exploration and sustained presence on the Moon, Mars, or elsewhere in the Solar System. In this issue, we present a collection of 20 articles, each providing perspectives or data relevant to the implementation of a countermeasure discovery and development program. Topics include agency and drug developer perspectives, the prospects for repurposing of existing drugs or other agents, and the potential for adoption of new technologies, high-throughput screening, novel animal or microphysiological models, and alternative ground-based radiation sources. Long-term goals of a countermeasures program include reduction in the risk of radiation-exposure induced cancer death to an acceptable level and reduction in risks to the brain, cardiovascular system, and other organs.
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Affiliation(s)
- William S Dynan
- Department of Radiation Oncology and Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, United States.
| | - Polly Y Chang
- SRI International, Biosciences Division, Menlo Park, CA, United States
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Sishc BJ, Zawaski J, Saha J, Carnell LS, Fabre KM, Elgart SR. The Need for Biological Countermeasures to Mitigate the Risk of Space Radiation-Induced Carcinogenesis, Cardiovascular Disease, and Central Nervous System Deficiencies. Life Sci Space Res (Amst) 2022; 35:4-8. [PMID: 36336368 DOI: 10.1016/j.lssr.2022.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [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: 04/08/2022] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 06/16/2023]
Abstract
NASA's currently planned long-duration, deep space exploration missions outside of low Earth orbit (LEO) will result in the exposure of astronauts to relatively high lifetime doses of ionizing radiation (IR), exceeding what humans have previously encountered in space. Of concern to this exposure are the long-term health consequences of radiation carcinogenesis, cardiovascular and degenerative disease, and central nervous system decrements. Existing engineering solutions are insufficient to decrease the lifetime accumulated IR exposure to levels currently allowable by agency standards, therefore appropriate countermeasure and mitigation strategies must be developed to enable long duration missions. Emerging discoveries in the fields of radiation oncology and the mitigation of Acute Radiation Syndrome (ARS) have demonstrated the potential for compound-based/biological radiomodifiers to drastically improve clinical outcomes and represent a promising strategy for space radiation countermeasure development. This review outlines the unique challenges posed by the space radiation environment, defines the limits of terrestrial radiation protection strategies in space, describes a brief overview of current space radiation countermeasure development strategies, highlights potential new approaches for countermeasure identification and development, and speculates on the potential benefits beyond space exploration.
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Affiliation(s)
| | | | | | - Lisa S Carnell
- NASA Physical and Biological Sciences Division, NASA Headquarters, Washington, D.C
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4
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Iwamoto KS, Sandstrom RE, Bryan M, Liu Y, Elgart SR, Sheng K, Steinberg ML, McBride WH, Low DA. Weak Magnetic Fields Enhance the Efficacy of Radiation Therapy. Adv Radiat Oncol 2021; 6:100645. [PMID: 33748547 PMCID: PMC7966835 DOI: 10.1016/j.adro.2021.100645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 06/18/2020] [Accepted: 12/02/2020] [Indexed: 11/17/2022] Open
Abstract
Purpose The clinical efficacy of radiation therapy is mechanistically linked to ionization-induced free radicals that cause cell and tissue injury through direct and indirect mechanisms. Free radical reaction dynamics are influenced by many factors and can be manipulated by static weak magnetic fields (WMF) that perturb singlet-triplet state interconversion. Our study exploits this phenomenon to directly increase ionizing radiation (IR) dose absorption in tumors by combining WMF with radiation therapy as a new and effective method to improve treatment. Methods and Materials Coils were custom made to produce both homogeneous and gradient magnetic fields. The gradient coil enabled simultaneous in vitro assessment of free radical/reactive oxygen species reactivity across multiple field strengths from 6 to 66 G. First, increases in IR-induced free radical concentrations using oxidant-sensitive fluorescent dyes in a cell-free system were measured and verified. Next, human and murine cancer cell lines were evaluated in in vitro and in vivo models after exposure to clinically relevant doses of IR in combination with WMF. Results Cellular responses to IR and WMF were field strength and cell line dependent. WMF was able to enhance IR effects on reactive oxygen species formation, DNA double-strand break formation, cell death, and tumor growth. Conclusions We demonstrate that the external presence of a magnetic field enhances radiation-induced cancer cell injury and death in vitro and in vivo. The effect extends beyond the timeframe when free radicals are induced in the presence of radiation into the window when endogenous free radicals are produced and therefore extends the applicability of this novel adjunct to cancer therapy in the context of radiation treatment.
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Affiliation(s)
- Keisuke S Iwamoto
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | | | - Mark Bryan
- Mark Bryan & Company LLC, Arcadia, California
| | - Yue Liu
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - S Robin Elgart
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Ke Sheng
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Michael L Steinberg
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - William H McBride
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Daniel A Low
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California
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Chappell LJ, Elgart SR, Milder CM, Semones EJ. Assessing Nonlinearity in Harderian Gland Tumor Induction Using Three Combined HZE-irradiated Mouse Datasets. Radiat Res 2020; 194:38-51. [PMID: 32330076 DOI: 10.1667/rr15539.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 03/20/2020] [Indexed: 11/03/2022]
Abstract
Recently reported studies considering nonlinearity in the effects of low-dose space radiation have assumed a nontargeted mechanism. To date, few analyses have been performed to assess whether a nontargeted term is supported by the available data. The Harderian gland data from Alpen et al. (published in 1993 and 1994), and Chang et al. (2016) provide the most diversity of ions and energies in a tumor induction model, including multiple high-energy and charge particles. These data can be used to investigate various nonlinearity assumptions against a linear model, including nontargeted effects in the low-dose region or cell sterilization at high doses. In this work, generalized linear models were used with the log complement link function to analyze the binomial data from the studies independently and combined. While there was some evidence of nonlinearity that was best described by a cell-sterilization model, the linear model was adequate to describe the data. The current data do not support the addition of a nontargeted effects term in any model. While adequate data are available in the low-dose region (<0.5 Gy) to support a nontargeted effects term if valid, additional data in the 1-2 Gy region are necessary to achieve power for cell-sterilization analysis validation. The current analysis demonstrates that the Harderian gland tumor data do not support the use of a nontargeted effects term in human cancer risk models.
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Elgart SR, Little MP, Chappell LJ, Milder CM, Shavers MR, Huff JL, Patel ZS. Radiation Exposure and Mortality from Cardiovascular Disease and Cancer in Early NASA Astronauts. Sci Rep 2018; 8:8480. [PMID: 29855508 PMCID: PMC5981602 DOI: 10.1038/s41598-018-25467-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [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: 01/02/2018] [Accepted: 04/17/2018] [Indexed: 12/04/2022] Open
Abstract
Understanding space radiation health effects is critical due to potential increased morbidity and mortality following spaceflight. We evaluated whether there is evidence for excess cardiovascular disease or cancer mortality in early NASA astronauts and if a correlation exists between space radiation exposure and mortality. Astronauts selected from 1959–1969 were included and followed until death or February 2017, with 39 of 73 individuals still alive at that time. Calculated standardized mortality rates for tested outcomes were significantly below U.S. white male population rates, including all-cardiovascular disease (n = 7, SMR = 33; 95% CI, 14–65) and all-cancer (n = 7, SMR = 43; 95% CI, 18–83), as anticipated in a healthy worker population. Space radiation doses for cohort members ranged from 0–78 mGy. No significant associations between space radiation dose and mortality were found using logistic regression with an internal reference group, adjusting for medical radiation. Statistical power of the logistic regression was <6%, remaining <12% even when expected risk level or observed deaths were assumed to be 10 times higher than currently reported. While no excess radiation-associated cardiovascular or cancer mortality risk was observed, findings must be tempered by the statistical limitations of this cohort; notwithstanding, this small unique cohort provides a foundation for assessment of astronaut health.
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Affiliation(s)
| | - Mark P Little
- Radiation Epidemiology Branch, National Cancer Institute, DHHS, NIH, Division of Cancer Epidemiology and Genetics, Bethesda, Maryland, USA
| | | | | | - Mark R Shavers
- KBRwyle, Science and Space Operations, Houston, Texas, USA
| | | | - Zarana S Patel
- KBRwyle, Science and Space Operations, Houston, Texas, USA.
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Norbury JW, Schimmerling W, Slaba TC, Azzam EI, Badavi FF, Baiocco G, Benton E, Bindi V, Blakely EA, Blattnig SR, Boothman DA, Borak TB, Britten RA, Curtis S, Dingfelder M, Durante M, Dynan WS, Eisch AJ, Robin Elgart S, Goodhead DT, Guida PM, Heilbronn LH, Hellweg CE, Huff JL, Kronenberg A, La Tessa C, Lowenstein DI, Miller J, Morita T, Narici L, Nelson GA, Norman RB, Ottolenghi A, Patel ZS, Reitz G, Rusek A, Schreurs AS, Scott-Carnell LA, Semones E, Shay JW, Shurshakov VA, Sihver L, Simonsen LC, Story MD, Turker MS, Uchihori Y, Williams J, Zeitlin CJ. Galactic cosmic ray simulation at the NASA Space Radiation Laboratory. Life Sci Space Res (Amst) 2016; 8:38-51. [PMID: 26948012 PMCID: PMC5771487 DOI: 10.1016/j.lssr.2016.02.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [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: 01/12/2016] [Revised: 02/02/2016] [Accepted: 02/02/2016] [Indexed: 05/21/2023]
Abstract
Most accelerator-based space radiation experiments have been performed with single ion beams at fixed energies. However, the space radiation environment consists of a wide variety of ion species with a continuous range of energies. Due to recent developments in beam switching technology implemented at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), it is now possible to rapidly switch ion species and energies, allowing for the possibility to more realistically simulate the actual radiation environment found in space. The present paper discusses a variety of issues related to implementation of galactic cosmic ray (GCR) simulation at NSRL, especially for experiments in radiobiology. Advantages and disadvantages of different approaches to developing a GCR simulator are presented. In addition, issues common to both GCR simulation and single beam experiments are compared to issues unique to GCR simulation studies. A set of conclusions is presented as well as a discussion of the technical implementation of GCR simulation.
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Affiliation(s)
| | - Walter Schimmerling
- East Carolina University, Greenville, NC 27858, USA; Universities Space Research Association, Houston, TX 77058, USA
| | - Tony C Slaba
- NASA Langley Research Center, Hampton, VA 23681, USA
| | | | | | - Giorgio Baiocco
- Department of Physics, University of Pavia, 27100, Pavia, Italy
| | - Eric Benton
- Oklahoma State University, Stillwater, OK 74074, USA
| | | | | | | | - David A Boothman
- University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | | | | - Stan Curtis
- 11771 Sunset Ave. NE, Bainbridge Island, WA 98110, USA
| | | | - Marco Durante
- GSI Helmholtz Center for Heavy Ion Research, 64291 Darmstadt, Germany
| | | | - Amelia J Eisch
- University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | | | | - Peter M Guida
- Brookhaven National Laboratory, Upton, NY 11973, USA
| | | | | | - Janice L Huff
- Universities Space Research Association, Houston, TX 77058, USA
| | - Amy Kronenberg
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | | | - Jack Miller
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Livio Narici
- University of Rome Tor Vergata & INFN, 00133 Rome, Italy
| | | | - Ryan B Norman
- NASA Langley Research Center, Hampton, VA 23681, USA
| | | | | | | | - Adam Rusek
- Brookhaven National Laboratory, Upton, NY 11973, USA
| | | | | | | | - Jerry W Shay
- University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | | - Lembit Sihver
- Technische Universität Wien - Atominstitut, 1020 Vienna, Austria; EBG MedAustron GmbH, 2700 Wiener Neustadt, Austria
| | | | - Michael D Story
- University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | | | - Yukio Uchihori
- National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | | | - Cary J Zeitlin
- Lockheed Martin Information Systems & Global Solutions, Houston, TX 77058, USA
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Elgart SR, Bostani M, Mok KC, Adibi A, Ruehm S, Enzmann D, McNitt-Gray M, Iwamoto KS. Investigation of DNA Damage Dose-Response Kinetics after Ionizing Radiation Schemes Similar to CT Protocols. Radiat Res 2015; 183:701-7. [PMID: 25950819 DOI: 10.1667/rr13752.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Although there has been extensive research done on the biological response to doses of ionizing radiation relevant to radiodiagnostic procedures, very few studies have examined radiation schemes similar to those frequently utilized in CT exams. Instead of a single exposure, CT exams are often made up of a series of scans separated on the order of minutes. DNA damage dose-response kinetics after radiation doses and schemes similar to CT protocols were established in both cultured (ESW-WT3) and whole blood lymphocytes and compared to higher dose exposures. Both the kinetics and extent of H2AX phosphorylation were found to be dose dependent. Damage induction and detection showed a clear dose response, albeit different, at all time points and differences in the DNA repair kinetics of ESW-WT3 and whole blood lymphocytes were characterized. Moreover, using a modified split-dose in vitro experiment, we show that phosphorylation of H2AX is significantly reduced after exposure to CT doses fractionated over a few minutes compared to the same total dose delivered as a single exposure. Because the split-dose exposures investigated here are more similar to those experienced during a CT examination, it is essential to understand why and how these differences occur. This work provides compelling evidence supporting differential biological responses not only between high and low doses, but also between single and multiple exposures to low doses of ionizing radiation.
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Affiliation(s)
| | - Maryam Bostani
- b Radiology, David Geffen School of Medicine at University of California, Los Angeles, California
| | | | - Ali Adibi
- b Radiology, David Geffen School of Medicine at University of California, Los Angeles, California
| | - Stefan Ruehm
- b Radiology, David Geffen School of Medicine at University of California, Los Angeles, California
| | - Dieter Enzmann
- b Radiology, David Geffen School of Medicine at University of California, Los Angeles, California
| | - Michael McNitt-Gray
- b Radiology, David Geffen School of Medicine at University of California, Los Angeles, California
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Elgart SR, Adibi A, Khatonabadi M, Ruehm S, Enzmann D, McNitt-Gray M, Iwamoto K. MO-D-134-09: Assessing DNA Damage Repair From CT Studies in Whole Blood. Med Phys 2013. [DOI: 10.1118/1.4815267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Elgart SR, Khatonabadi M, McNitt-Gray M, Ruehm S, Adibi A, Iwamoto K. WE-A-218-02: Assessing the Repair of DNA Damage from Multi-Pass CT Protocols. Med Phys 2012. [DOI: 10.1118/1.4736071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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