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At least 937 records · Page 52Linked to original sources
PubMed2006

L-selenomethionine modulates high LET radiation-induced alterations of gene expression in cultured human thyroid cells.

L-selenomethionine (SeM) is emerging as a highly effective protective agent against radiation-induced biological effects. We have shown its protective effect on space radiation-induced death of MCF-10 cells as well as on space radiation-induced transformation of HTori-3 cells. The present study was aimed at elucidation of molecular mechanisms and cellular pathways involved in SeM-mediated radioprotection. Human thyroid epithelial cells (HTori-3 cells), in the presence or absence of SeM, were exposed to a non-toxic or a slightly toxic radiation dose from 1 GeV/n iron ions (10 cGy and 20 cGy, respectively). Total RNA was prepared and changes in gene expression were analyzed using microarray technology. Our analysis has revealed a dramatic effect of SeM on alterations of gene expression caused by space radiation. This study provides a basis for furthering our knowledge about radiation-induced molecular and cellular changes that lead to cellular transformation and death.

Aerospace Medicine↗
PubMed2004

[Scientific substantiation of experimental determination of the radiation effective dose in an interplanetary flight].

The present-day method of effective dose determination with a simplified human body model (spherical phantom) lacks the parameter of vehicle shielding. Introduction of the parameter will increase only the effective depth of various critical organs in the spherical phantom which can be easily accounted for during preliminary calculations. In future these facts, as well as data about impacts of the angular distribution of galactic cosmic rays (GCR), will be integrated into the calculation procedure. Analysis of the GCR dose contribution will not be very intricate owing to the GCR spectrum stability and isotropy of the angular distribution. Thus, basic calculation and measurement procedures will be fully unaltered.

Cosmic Radiation↗
PubMed1994

Space radiobiology program in Russia.

The space radiobiology program in Russia is aimed at obtaining fundamental data for developing radiation safety criteria. These criteria are necessary for long-term space missions. This program includes : -substantiation of radiation hazard estimation principles based on the radiation risk conception, -investigation of the radiation affection regularities under the combined influence of the spaceflight factors, -experimental investigation of the HZE-particle delayed effects and acute somatic effects induced by protons and electrons, -individual radiosensitivity investigation, -mathematic modeling of radiobiological effects , -radiobiological basis of control and forecast of radiation influence in space, -development of methods and means of an organism's radioresistance increase.

Aerospace Medicine↗
PubMed1998

Performance of a digital video camcorder for the Autonomous Biological System experiment onboard Space Station Mir.

A video imaging and recording system was utilized in the Autonomous Biological System experiment onboard the space station Mir. Video image of the mini-ecological system was successfully recorded. The whole system was retrieved to the ground after its operation in orbit for four months. Performance of the video system is summarized here together with technical problems encountered. Defects of pixel had been developed in the imaging device. Cause of these defects could be attributed to its exposure against space radiation. Auto white balance was another function of the camcorder that was deviated from normal range of its performance once in orbit but recovered to normal after a while. Possible use of imaging devices for dosimetry is proposed to record space radiation environment at the site close to the experiment.

Animals↗
PubMed1972

Influence of Cosmos 368 space flight conditions on radiation effects in yeasts, hydrogen bacteria and seeds of lettuce and pea.

Radiobiological studies have been carried out on board the Cosmos 368 satellite, launched on 8 October 1970 and returning to earth on 14 October 1970. Yeast diploid cells Saccharomyces ellipsoides, Megri strain 139-B, haploid cells Zygosaccharomyces Baili, hydrogen bacteria Hydrogenomonas eutropha, strain Z-1, Berlin variety lettuce seeds and Capital variety pea seeds were used in these experiments. The biological specimens were irradiated with gamma-rays at dose rates of 71.8 and 6.7 rad d-1 suring the packaging of containers and after returning the samples to the laboratory. It was found that both on pre-radiation and post-radiation exposure space flight factors did not greatly influence radiobiological effects.

Cosmic Radiation↗
PubMedDate not supplied

[Cosmophysical correlations in live and non-live nature as a manifestation of weak interactions].

Determination of weak effects is proposed, their relationship with cosmophysical correlations is advanced. The experimental results are presented on the intensification coefficient of weak effects (10(4)) for polarized electromagnetic radiation. The magnetoresonance mechanism of weak effects is suggested. The experimental evidence in favor of this mechanism and its application to the problems of cosmophysical correlations are given.

Biophysical Phenomena↗
PubMed2000

Overview of radiation environments and human exposures.

Human exposures to ionizing radiation have been vastly altered by developing technology in the last century. This has been most obvious in the development of radiation generating devices and the utilization of nuclear energy. But even air travel has had its impact on human exposure. Human exposure increases with advancing aircraft technology as a result of the higher operating altitudes reducing the protective cover provided by Earth's atmosphere from extraterrestrial radiations. This increase in operating altitudes is taken to a limit by human operations in space. Less obvious is the changing character of the radiations at higher altitudes. The associated health risks are less understood with increasing altitude due to the increasing complexity and new field components found in high-altitude and space operations.

Aircraft↗
PubMed2005

A model of chromosome aberration induction: applications to space research.

A mechanistic model and Monte Carlo code simulating chromosome aberration induction in human lymphocytes is presented. The model is based on the assumption that aberrations arise from clustered DNA lesions and that only the free ends of clustered lesions created in neighboring chromosome territories or in the same territory can join and produce exchanges. The lesions are distributed in the cell nucleus according to the radiation track structure. Interphase chromosome territories are modeled as compact intranuclear regions with volumes proportional to the chromosome DNA contents. Both Giemsa staining and FISH painting can be simulated, and background aberrations can be taken into account. The good agreement with in vitro data provides validation of the model in terms of both the assumptions adopted and the simulation techniques. As an application in the field of space research, the model predictions were compared with aberration yields measured among crew members of long-term missions on board Mir and ISS, assuming an average radiation quality factor of 2.4. The agreement obtained also validated the model for in vivo exposure scenarios and suggested possible applications to the prediction of other relevant aberrations, typically translocations.

Chromosome Aberrations↗
PubMed1993

Longitudinal study of astronaut health: mortality in the years 1959-1991.

We conducted a historical cohort study of mortality among 195 astronauts who were exposed to space and medical sources of radiation between 1959 and 1991. Cumulative occupational and medical radiation exposures were obtained from the astronaut radiation exposure history data base. Causes of death were obtained from obligatory death certificates and autopsy reports that were on file in the medical records. There was a total of 20 deaths that occurred during the 32-year follow-up period of which 16 were due to accidents. The all-cause standardized mortality ratio (SMR) was 181 (95% confidence interval 110, 279). There was 1 cancer death in the buccal cavity and pharyngeal ICD-9 rubric whose occurrence was significantly beyond expectation. Mortality for coronary disease was 53% lower than expected (2 deaths; SMR = 47; 95% confidence limits 5, 168). The crude death rate for 12 occupationally related accidents was 445 deaths per 100,000 person-years and was an order of magnitude greater than accidental death rates in the mining industries. The SMR of 1346 for fatal accidents was significantly beyond expectation (16 deaths; 95% confidence limits 769, 2168) and was similar to SMRs for accidents among aerial pesticide applicators. The 10-year cumulative risk of occupational fatalities based on the exponential, Weibull, Gompertz, and linear-exponential distributions was 10%. Mortality from motor vehicle accidents was slightly higher than expected, but was not significant (1 death; SMR = 165; 95% confidence limits 2,922). Radiation exposures from medical procedures accounted for a majority of cumulative dose when compared with space radiation exposures. Overall, it was found that astronauts are at a health disadvantage as a result of catastrophic accidents.

Cause of Death↗
PubMed2000

Radiation exposure for human Mars exploration.

One major obstacle to human space exploration is the possible limitations imposed by the adverse effects of long-term exposure to the space environment. Even before human space flight began, the potentially brief exposure of astronauts to the very intense random solar energetic particle events was of great concern. A new challenge appears in deep-space exploration from exposure to the low-intensity heavy-ion flux of the galactic cosmic rays since the missions are of long duration, and accumulated exposures can be high. Because cancer induction rates increase behind low to moderate thicknesses of aluminum shielding, according to available biological data on mammalian exposures to galactic cosmic ray-like ions, aluminum shield requirements for a Mars mission may be prohibitively expensive in terms of mission launch costs. Alternative materials for vehicle construction are under investigation to provide lightweight habitat structures with enhanced shielding properties. In the present paper, updated estimates for astronaut exposures on a Mars mission are presented and shielding properties of alternative materials are compared with aluminum.

Cosmic Radiation↗
PubMed1996

Geomagnetic transmission disturbances and heavy-ion fluences observed in low Earth orbit during the solar energetic particle events of October 1989.

The large solar energetic particle (SEP) events and simultaneous large geomagnetic disturbances observed during October 1989 posed a significant, rapidly evolving space radiation hazard. Using data from the GOES-7, NOAA-10, IMP-8 and LDEF satellites, we determined the geomagnetic transmission, heavy ion fluences, mean Fe ionic charge state, and effective radiation hazard observed in low Earth orbit (LEO) for these SEPs. We modeled the geomagnetic transmission by tracing particles through the combination of the internal International Geomagnetic Reference Field (IGRF) and the Tsyganenko (1989) magnetospheric field models, extending the modeling to large geomagnetic disturbances. We used our results to assess the radiation hazard such very large SEP events would pose in the anticipated 52 degrees inclination space station orbit.

Cosmic Radiation↗
PubMed1978

Radiobiological results from the Bacillus subtilis Biostack experiments within the Apollo and the ASTP space flights.

In order to check the results of earlier Biostack experiments, new experimental techniques were developed for the Biostack III experiment in the Apollo-Soyuz test project (ASTP). These techniques resulted in an increased accuracy of localization down to 0.2 micrometers for the determination of the impact parameter, accompanied by an increase in the sample size available for biological investigation. In addition, colony forming ability, metabolic mutations, and mutations affecting UV- and x-ray sensitivity were rendered observable by these methods. The biological and physical results obtained so far from the evaluation of the Bacillus subtilis experiment within Biostack III confirm and extend the findings of the previous Biostack experiments. They also add to the questions about the mechanisms of action of the radiation field under investigation, since the observed effects cannot be interpreted in terms of standard concepts.

Bacillus subtilis↗
PubMed1999

[State of cardiovascular system in immediate and delayed periods following exposure of organism to ionizing radiation].

Data on the progress of radiation damages and the character of shifts in the cardiovascular functioning following exposure to ionizing radiation as a function of dose were analyzed. Reviewed were experimental and clinical material, and records of periodic medical examinations of persons who had worked long with sources of ionizing radiation. A plausible character of deviations in health and working ability of cosmonauts in flight and at the end of career due to cardiovascular disorders is described.

Animals↗
PubMed2004

Radiation response mechanisms of the extremely radioresistant bacterium Deinococcus radiodurans.

Effect of microgravity on recovery of bacterial cells from radiation damage was examined in IML-2, S/MM-4 and S/MM-9 experiments using the extremely radioresistant bacterium Deinococcus radiodurans. The cells were irradiated with gamma rays before the space flight and incubated on board the Space Shuttle. The survival of the wild type cells incubated in space increased compared with the ground controls, suggesting that the recovery of this bacterium from radiation damage was enhanced under the space environment. No difference was observed between the survivals of radiosensitive mutant rec30 cells incubated in space and on the ground. The amount of DNA-repair related RecA protein induced under microgravity was similar to those of ground controls, however, induction of PprA protein, product of a unique radiation-inducible gene (designated pprA) responsible for loss of radiation resistance in repair-deficient mutant, KH311, was enhanced under microgravity compared with ground controls. Recent investigation in vitro showed that PprA preferentially bound to double-stranded DNA carrying strand breaks, inhibited Escherichia coli exonuclease III activity, and stimulated the DNA end-joining reaction catalyzed by DNA ligases. These results suggest that D. radiodurans has a radiation-induced non-homologous end-joining (NHEJ) repair mechanism in which PprA plays a critical role.

Bacterial Proteins↗
PubMed1992

Radiobiological studies with the nematode Caenorhabditis elegans. Genetic and developmental effects of high LET radiation.

The biological effects of heavy charged particle (HZE) radiation are of particular interest to travellers and planners for long-duration space flights where exposure levels represent a potential health hazard. The unique feature of HZE radiation is the structured pattern of its energy deposition in targets. There are many consequences of this feature to biological endpoints when compared with effects of ionizing photons. Dose vs response and dose-rate kinetics may be modified, DNA and cellular repair systems may be altered in their abilities to cope with damage, and the qualitative features of damage may be unique for different ions. The nematode Caenorhabditis elegans is being used to address these and related questions associated with exposure to radiation. HZE-induced mutation, chromosome aberration, cell inactivation and altered organogenesis are discussed along with plans for radiobiological experiments in space.

Animals↗
PubMed2003

Radiation environment monitoring for manned missions to Mars.

In this paper a radiation monitoring system for manned Mars missions is described, based on the most recent requirements on crew radiation safety. A comparison is shown between the radiation monitoring systems for Earth-orbiting and interplanetary spacecraft, with similarities and differences pointed out and discussed. An operational and technological sketch of the chosen problem solving approach is also given.

Cosmic Radiation↗
PubMed2006

Chemistry and cosmology.

The simplest elements, hydrogen and helium, offer a remarkably rich chemistry, which has controlled crucial features of the early evolution of the universe. Theoretical models of the origin of structure (stars, galaxies, clusters of galaxies, etc.) now incorporate this chemistry in some detail. In addition to the origin of structure, cosmologists are concerned with observational tests of competing world models. Primordial chemistry may give rise to some of the earliest departures from thermodynamic equilibrium in the universe. These effects may be observable as broad-band spectroscopic distortions of the cosmic background radiation, which otherwise exhibits a nearly perfect blackbody spectrum. The chemical history of the expanding universe is followed through a detailed calculation of the evolution of the abundances of H, H+, H-, H2, H2+, H3+, and other minor species. It is shown that continuous absorption by the small concentration of H- can produce a distortion in the cosmic background spectrum with a maximum at a frequency near nu/c = 9 cm-1 (wavelength 1.1 mm). The predicted effect lies only a factor of 5 below current limits. Its detection would provide an important test of our understanding of the recombination epoch of the universe.

Journal Article↗