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We measured the charge of about 35000 projectile fragments with Z > or = 5e produced by 14.5 GeV/nucleon and 200 GeV/nucleon 16O beams in a Pb target using CR39 plastic nuclear track detectors. A minimum track length of 3 mm in the detector without nuclear interaction was required. No evidence for fragments carrying a fractional charge was found.
We calculate the coherent production of pions from subthreshold to relativistic energies in heavy-ion collisions using a quantum, microscopic, many-body model. For the first time, in this approach, we use harmonic oscillator wave functions to describe shell-model information. The theoretical quantum mechanical results obtained for the pion spectra represent an important improvement over our previous microscopic, many-body calculations.
Transgenic mice that differed in their p53 genetic status were exposed to an acute dose of highly charged and energetic (HZE) iron particle radiation. Micronuclei (MN) in two distinct populations of circulating peripheral blood erythrocytes, the immature reticulocytes (RETs) and the mature normochromatic erythrocytes (NCEs), were measured using a simple and efficient flow cytometric procedure. Our results show significant elevation in the frequency of micronucleated RETs (%MN-RETs) at 2 and 3 days post-radiation. At 3 days post-irradiation, the magnitude of the radiation-induced MN-RET was 2.3-fold higher in the irradiated p53 wild-type animals compared to the unirradiated controls, 2.5-fold higher in the p53 hemizygotes and 4.3-fold higher in the p53 nullizygotes. The persistence of this radiation-induced elevation of MN-RETs is dependent on the p53 genetic background of the animal. In the p53 wild-type and p53 hemizygotes, %MN-RETs returned to control levels by 9 days post-radiation. However, elevated levels of %MN-RETs in p53 nullizygous mice persisted beyond 56 days post-radiation. We also observed elevated MN-NCEs in the peripheral circulation after radiation, but the changes in radiation-induced levels of MN-NCEs appear dampened compared to those of the MN-RETs for all three strains of animals. These results suggest that the lack of p53 gene function may play a role in the iron particle radiation-induced genomic instability in stem cell populations in the hematopoietic system.
Future space missions will involve long-term travel beyond the magnetic field of the Earth, where astronauts will be exposed to radiation hazards such as those that arise from galactic cosmic rays. Galactic cosmic rays are composed of protons, alpha particles, and particles of high energy and charge (HZE particles). Research by our group has shown that exposure to HZE particles, primarily 600 MeV/n and 1 GeV/n 56Fe, can produce significant alterations in brain neurochemistry and behavior. However, given that protons can make up a significant portion of the radiation spectrum, it is important to study their effects on neural functioning and on related performance. Therefore, these studies examined the effects of exposure to proton irradiation on neurochemical and behavioral endpoints, including dopaminergic functioning, amphetamine-induced conditioned taste aversion learning, and spatial learning and memory as measured by the Morris water maze. Male Sprague-Dawley rats received a dose of 0, 1.5, 3.0 or 4.0 Gy of 250 MeV protons at Loma Linda University and were tested in the different behavioral tests at various times following exposure. Results showed that there was no effect of proton irradiation at any dose on any of the endpoints measured. Therefore, there is a contrast between the insignificant effects of high dose proton exposure and the dramatic effectiveness of low dose (<0.1 Gy) exposures to 56Fe particles on both neurochemical and behavioral endpoints. Published by Elsevier Ltd on behalf of COSPAR.
The present volume is a collection of 227 abstracts of radiation research sponsored by the NASA Space Radiation Health Program for the period 1991-1992. Each abstract has been categorized within one of three discipline areas: Physics, Biology and Risk Assessment. Topic areas within each discipline have been assigned as follows: Physics - Atomic Physics, Theory, Cosmic Ray and Astrophysics, Experimental, Environments and Environmental Models, Solar Activity and Prediction, Experiments, Radiation Transport and Shielding, Theory and Model Development, Experimental Studies, and Instrumentation. Biology - Biology, Molecular Biology, Cellular Radiation Biology, Transformation, Mutation, Lethality, Survival, DNA Damage and Repair, Tissue, Organs, and Organisms, In Vivo/In Vitro Systems, Carcinogenesis and Life Shortening, Cataractogenesis, Genetics/Developmental, Radioprotectants, Plants, and Other Effects. Risk Assessment - Risk Assessment, Radiation Health and Epidemiology, Space Flight Radiation Health Physics, Inter- and Intraspecies Extrapolation and Radiation Limits and Standards. Section I contains refereed journals; Section II contains reports/meetings. Keywords and author indices are provided. A collection of abstracts spanning the period 1986-1990 was previously issued as NASA Technical Memorandum 4270.
Radial integrals have been calculated under the one-electron hydrogenic model. Two different values of the effective charge parameter, one for the initial state and the other for the final state, are retained in these formulae. The model is able to reasonably reproduce the existing dipole oscillator strength values with little effort. The dipole oscillator strength values are given for many ions for the first time.
The upper limit of momentum transfer by a proton to K-shell electrons is calculated in a restricted three-body classical model. The model shows that the infinite upper limit used in practice, is generally good except for low energy protons passing through an extremely rarefied gas.
Age-related modifications of DNA bases have been observed in the liver of the New Zealand white (NZW) rabbit (Oryctolagus cuniculus), a lagomorph with a median life span in captivity of 5-7 yr. The ages of the animals studied ranged from 6 wk to 9 yr. After the DNA had been extracted from the liver cell nuclei and hydrolyzed with acid, the bases were analyzed by column chromatography with Cellulofine gels (GC-15-m). Two peaks in the chromatogram, which eluted before the four DNA bases, contained modified bases. Those materials, which were obtained in relatively large amounts from old animals, were highly fluorescent, and were shown to be crosslinked base products by mass spectrometry. The yield of crosslinked products versus rabbit age (greater than 0.5 yr) can be fitted by an exponential function (correlation coefficient: 0.76 +/- 0.09).
Energetic heavy ions pose a great health risk to astronauts in extended ISS and future exploration missions. High-LET heavy ions are particularly effective in causing various biological effects, including cell inactivation, genetic mutations and cancer induction. Most of these biological endpoints are closely related to chromosomal damage, which can be utilized as a biomarker for radiation insults. Previously, we had studied chromosome aberrations in human lymphocytes and fibroblasts induced by both low- and high-LET radiation using FISH and multicolor fluorescence in situ hybridization (mFISH) techniques. In this study, we exposed human cells in vitro to gamma rays and energetic particles of varying types and energies and dose rates, and analyzed chromosomal damages using the multicolor banding in situ hybridization (mBAND) procedure. Confluent human epithelial cells and lymphocytes were exposed to energetic heavy ions at NASA Space Radiation Laboratory (NSRL) at the Brookhaven National Laboratory (Upton, NY) or Cs-137 gamma radiation source at the Baylor College (Houston, TX). After colcemid and Calyculin A treatment, cells were fixed and painted with XCyte3 mBAND kit (MetaSystems) and chromosome aberrations were analyzed with mBAND analysis system (MetaSystems). With this technique, individually painted chromosomal bands on one chromosome allowed the identification of interchromosomal aberrations (translocation to unpainted chromosomes) and intrachromosomal aberrations (inversions and deletions within a single painted chromosome). The possible relationship between the frequency of inter- and intra-chromosomal exchanges and the track structure of radiation is discussed. The work was supported by the NASA Space Radiation Health Program.
In February 2023, the Space Radiation Element of the NASA Human Research Program initiated a virtual, annual space radiation curriculum. The Space Health Impacts for the NASA Experience (SHINE) Space Radiation Didactic Curriculum aims to educate participants not only in the scientific aspects of space radiation but also in the agency’s risk management strategies. SHINE Space Radiation Didactic Curriculum combined weekly seminars by speakers from NASA, other government agencies, academia, and industry, with networking sessions designed to foster collaboration between the competitively selected participants as well as interactions with NASA scientists and HRP funded investigators. The inaugural course ran weekly from February 2023 to August 2023 and was comprised of lectures, less formal coffee hours, and office hours. Each two-hour seminar sessions hosted 1-3 presentations on topics which ranged from the space radiation environment to health effects and countermeasure to granting opportunities. All lectures were recorded and will be published on the THREE (The Health Risks of Extraterrestrial Environments) website for public access (https://three.jsc.nasa.gov/). As a course requirement, participants developed individual or collaborative beam time proposals for real, proposed, or potential experiments at the NASA Space Radiation Laboratory (NSRL) at the Brookhaven National Laboratory. For the 2023 course, 25 participants were selected from a total of 59 applicants. Selected participants were citizens from 8 countries and comprised 5 graduate students, 4 postdocs, 11 scientists and 5 professors/medical doctors. Participants had a wide range of expertise including molecular and cellular biology, microbiology, botany, physiology, engineering, physics, aerospace medicine, planetary science, biostatistics, and modeling. The second annual SHINE training program is scheduled from February to August 2024. In addition, a separate SHINE Space Radiation Practicum session will be held in Fall 2024 at the NSRL. The SHINE Space Radiation Practicum is a unique opportunity that has not been available to the public since the closure of the NASA Space Radiation Summer School in 2017 and will allow a small cohort of participants competitively selected in Fall 2023 to gain hands-on radiation experience.
The Space Radiation Element of the NASA Human Research Program initiated a virtual, annual space radiation curriculum. The Space Health Impacts for the NASA Experience (SHINE) space radiation didactic curriculum aims to educate participants not only in the scientific aspects of space radiation but also in the agency’s risk management strategies. SHINE combines weekly seminars by speakers from NASA, other government agencies, academia, and industry, with networking sessions designed to foster collaboration between participants and interactions with NASA scientists and HRP funded investigators. The inaugural course ran weekly from February 2023 to August 2023 and was comprised of lectures, less formal coffee hours and office hours. The SHINE topics ranged from space environments to health effects and countermeasure to granting opportunities. Participants developed beam time proposals for real, proposed, or potential experiments at the NASA Space Radiation Laboratory (NSRL) at the Brookhaven National Laboratory. For the 2023 course, a total of 59 applications were received from which 25 participants were selected. Selected participants were citizens from 8 countries and comprised 5 graduate students, 4 postdocs, 11 scientists and 5 professors/medical doctors. Participants had a wide range of expertise including molecular and cellular biology, microbiology, botany, physiology, engineering, physics, aerospace medicine, planetary science, biostatistics, and modeling. The second annual SHINE training program is scheduled from February to August 2024. In addition, a separate SHINE space radiation practicum session, to allow participants to gain hands-on radiation experience, will be held Fall 2024 at the NSRL.
The human exploration of Mars will impose unavoidable health risks from galactic cosmic rays (GCR) and possibly solar particle events (SPE). It is the goal of NASA's Space Radiation Health Program to develop the capability to predict health risks with significant accuracy to ensure that risks are well below acceptable levels and to allow for mitigation approaches to be effective at reasonable costs. End-to-End risk assessment is the approach being followed to understand proton and heavy ion damage at the molecular, cellular, and tissue levels in order to predict the probability of the major health risk including cancer, neurological disorders, hereditary effects, cataracts, and acute radiation sickness and to develop countermeasures for mitigating risks.
The Space Radiation Element part of NASA Human Research Program initiated a virtual, annual space radiation curriculum. The SHINE space radiation curriculum aims to educate participants not only in the scientific aspects of space radiation but also in the agency’s risk management strategies. SHINE combines weekly seminars by speakers from NASA, other government agencies, academia, and industry, with networking sessions designed to foster collaboration between participants and interactions with NASA scientists. A total of 59 applications were received from which 25 participants were selected. The 25 participants, with citizenship from a total of 8 countries, are composed of 5 graduate students, 4 postdocs, 11 scientists and 5 professors/medical doctors. Participants have a wide range of expertise including molecular and cellular biology, microbiology, botany, physiology, engineering, physics, aerospace medicine, planetary science, biostatistics, and modeling. The inaugural course ran weekly from February 2023 to August 2023 and was comprised of lectures, less formal coffee hours and office hours. The topics covered ranged from space environments to health effects to granting opportunities. The second annual SHINE training program is scheduled from February to August 2024. In addition, a separate competitive practicum session, to allow participants to gain hands-on radiation experience, will be held Fall 2024 at the NASA Space Radiation Laboratory (NSRL).
The Space Radiation Element part of NASA Human Research Program initiated a virtual, annual space radiation curriculum. The SHINE space radiation curriculum aims to educate participants not only in the scientific aspects of space radiation but also in the agency’s risk management strategies. SHINE combines weekly seminars by speakers from NASA, other government agencies, academia, and industry, with networking sessions designed to foster collaboration between participants and interactions with NASA scientists. A total of 59 applications were received from which 25 participants were selected. The 25 participants, with citizenship from a total of 8 countries, are composed of 5 graduate students, 4 postdocs, 11 scientists and 5 professors/medical doctors. Participants have a wide range of expertise including molecular and cellular biology, microbiology, botany, physiology, engineering, physics, aerospace medicine, planetary science, biostatistics, and modeling. The inaugural course ran weekly from February 2023 to August 2023 and was comprised of lectures, less formal coffee hours and office hours. The topics covered ranged from space environments to health effects to granting opportunities. The second annual SHINE training program is scheduled from February to August 2024. In addition, a separate competitive practicum session, to allow participants to gain hands-on radiation experience, will be held Fall 2024 at the NASA Space Radiation Laboratory (NSRL).
The topics of this presentation are: a brief review of the early research, the ideas it stimulated and the ways they are used in current efforts to explain cellular radiosensitivity; an analysis of the strengths and weaknesses of two experimental models used in vitro for simulating the induction of double strand breaks (DSB) and single strand breaks (SSB) in situ. Note that when alkali is used to denature cellular DNA for the determination of strand breaks, both overt SSB and the SSB that result from DSB in the denaturation process are recorded as total strand breaks (TSB). All information is taken from published literature.
An Interagency Panel Session organized by the NASA Human Research Program Space Radiation Program Element (SRPE) was held during the NASA Human Research Program (HRP) Investigator’s Workshop (IWS) in Galveston, Texas on January 26, 2017 to identify complementary research areas that will advance the testing and development of medical countermeasures (MCM) in support of radioprotection and radiation mitigation on the ground and in space. There were several areas of common interest identified among the various participating agencies. This report provides a summary of the topics discussed by each agency along with potential areas of intersection for mutual collaboration opportunities. Common goals included repurposing of pharmaceuticals, neutraceuticals for use as radioprotectors and/or mitigators, low-dose/chronic exposure paradigms, late effects post-radiation exposure, mixed-field exposures of gamma-neutron, performance decrements, and methods to determine individual exposure levels.
Chromosome aberrations were investigated in human lymphocytes after in vitro exposure to 1H-, 3He-, 12C-, 40Ar-, 28Si-, 56Fe-, or 197Au-ion beams, with LET ranging from approximately 0.4-1393 keV/microm in the dose range of 0.075-3 Gy. Dose-response curves for chromosome exchanges, measured at the first mitosis postirradiation using fluorescence in situ hybridization (FISH) with whole-chromosome probes, were fitted with linear or linear-quadratic functions. The relative biological effectiveness (RBE) was estimated from the initial slope of the dose-response curve for chromosomal damage with respect to low- or high-dose-rate gamma rays. Estimates of RBEmax values for mitotic spreads, which ranged from near 0.7 to 11.1 for total exchanges, increased with LET, reaching a maximum at about 150 keV/microm, and decreased with further increase in LET. RBEs for complex aberrations are undefined due to the lack of an initial slope for gamma rays. Additionally, the effect of mitotic delay on RBE values was investigated by measuring chromosome aberrations in interphase after chemically induced premature chromosome condensation (PCC), and values were up to threefold higher than for metaphase analysis.
Confluent human fibroblast cells (AG1522) were irradiated with gamma rays, 490 MeV/nucleon silicon ions, or iron ions at either 200 or 500 MeV/nucleon. The cells were allowed to repair at 37 degrees C for 24 h after exposure, and a chemically induced premature chromosome condensation (PCC) technique was used to condense chromosomes in the G2 phase of the cell cycle. Incomplete and complex exchanges were analyzed in the irradiated samples. To verify that chromosomal breaks were truly unrejoined, chromosome aberrations were analyzed using a combination of whole-chromosome specific probes and probes specific for the telomere region of the chromosome. Results showed that the frequency of unrejoined chromosome breaks was higher after irradiation with the heavy ions of high LET, and consequently the ratio of incomplete to complete exchanges increased steadily with LET up to 440 keV/microm, the highest LET included in the present study. For samples exposed to 200 MeV/nucleon iron ions, chromosome aberrations were analyzed using the multicolor FISH (mFISH) technique, which allows identification of both complex and truly incomplete exchanges. Results of the mFISH study showed that 0.7 and 3 Gy iron ions produced similar ratios of complex to simple exchanges and incomplete to complete exchanges; these ratios were higher than those obtained after exposure to 6 Gy gamma rays. After 0.7 Gy of iron ions, most complex aberrations were found to involve three or four chromosomes, which is a likely indication of the maximum number of chromosome domains traversed by a single iron-ion track.