Research Containing: Radiation

Stability of chromosome aberrations in the blood lymphocytes of astronauts measured after space flight by FISH chromosome painting

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Follow-up measurements of chromosome aberrations in the blood lymphocytes of astronauts were performed by FISH chromosome painting at various intervals from 5 months to more than 5 years after space flight and compared to preflight baseline measurements. For five of the six astronauts studied, the analysis of individual time courses for translocations revealed a temporal decline of yields with half-lives ranging from 10 to 58 months. The yield of exchanges remained unchanged for the sixth astronaut during an observation period of 5 months after flight. These results may indicate complications with the use of stable aberrations for retrospective dose reconstruction, and the differences in the decay time may reflect individual variability in risk from space radiation exposure.

Radiobiological results of the Biostack experiment on board Apollo 16 and 17

by cfynanon 9 June 2015in Biology & Biotechnology No comment

After penetrating the Biostack capsule, some of the HZE particles hit the biological objects carried: bacterial spores (Bacillus subtilis), seeds (Arabidopsis thaliana and Vicia faba), and shrimp eggs (Artemia salina). The different biological objects were affected by heavy ions in widely varying ways. A broad range of radiobiological investigations has been carried out in regard to the objects' response to HZE particles. The most sensitive biological objects in the Biostack experiments proved to be the shrimp eggs. The development of 500 eggs hit by heavy cosmic ions was investigated. This differed significantly from the flight controls (eggs flown in the Biostack but not hit by heavy ions) and from the ground controls. From this it has been concluded that penetration on the part of a single heavy ion may injure the encysted blastula. This damage was found to influence gastrula formation and even the hatching process of the nauplius. Abnormalities (increased by a factor of 10) in the orthonauplius were observed during the development of the hit eggs; they consisted, for example, of shortened extremities or an abnormal thorax or abdomen. In addition, eggs of Tribolium confusum and Carausius morosus, which were included in Biostack 2 (Apollo 17), have been investigated, and the influence of single heavy ions on the development process of these highly organized insects has been studied.

Introduction to The Proposed Space Experiments Aboard The ISS Using The Silkworm, Bombyx mori

by cfynanon 9 June 2015in Biology & Biotechnology No comment

The authors have a plan to examine the biological effects of cosmic rays by loading the eggs of the silkworm, Bombyx mori, in the International Space Station (ISS) for 3 months. In advance of the project, several ground experiments have been performed. In order to investigate the biological effects of radiation, heavy ion particles were used instead of cosmic rays. Heterozygous eggs of the black-striped strain (pS/p) were irradiated with Carbon (C), Neon (Ne) or Ferrous (Fe) ion particles. At the fifth instar stage, larvae that hatched from these eggs showed white spots on their backs against the black or dark brown of their integument. These are somatic mutations which seem to be caused by the effects of radiation on the pS gene. The incidence of this somatic mutation increased in proportion to dose and linear energy transfer of C and Ne ion particles, and it was higher after resumption of embryogenesis in eggs that had been irradiated after diapause termination as compared with eggs irradiated while still in diapause. Irradiation by more than 0.04 Gy of Fe ion particles to diapause-terminated eggs induced a significant incidence of somatic mutation compared with controls (P<0.05). Furthermore, radiation effects were also detected at the next generation as detected by egg color mutations by using the specific locus method. In experiments investigating the effects of microgravity on silkworm embryogenesis in the US Space Shuttle/Atlantis (STS-84) in 1997, we had observed that microgravity could influence embryonic reversal, presumably resulting in abnormal development of embryos. On the basis of the results from STS-84 flight and the above mentioned ground experiments, the authors will examine the interrelationship between the dose of cosmic rays and the incidence of somatic mutation, as well as confirm and extend the analysis of synergistic effects between cosmic rays and microgravity on mutation rates in experiments conducted using the ISS. These data will provide fundamental information on the effects of cosmic rays on biological systems that can then be applied to better protect humans against cosmic radiation during space flight.

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Targeted Heavy-Ion Microbeam Irradiation of the Embryo But Not Yolk in the Diapause-Terminated Egg of the Silkworm, Bombyx mori, Induces The Somatic Mutation

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Using heavy-ion microbeam, we report target irradiation of selected compartments within the diapause-terminated egg and its mutational consequences in the silkworm, Bombyx mori. On one hand, carbon-ion exposure of embryo to 0.5-6 Gy increased the somatic mutation frequency, suggesting targeted radiation effects. On the other, such increases were not observed when yolk was targeted, suggesting a lack of nontargeted bystander effect.

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Embryonic development in the eggs of the silkworm, Bombyx mori, exposed to the space environment

by cfynanon 9 June 2015in Biology & Biotechnology No comment

To investigate the effects of cosmic radiation and microgravity on embryogenesis and organogenesis in Bombyx eggs, two different stages of eggs, the early stage after oviposition and the diapause-terminated eggs, were loaded on the US Space Shuttle/Atlantis (STS-84) for a 9 day flight. More than 85% of the early stage eggs hatched in the flight sample and the ground control. In the diapause-terminated eggs, the percentage of unhatched eggs were 43% in the ground control and 56% in the flight sample. In these eggs, uncompleted embryonic reversal was observed two-fold higher percentage in the flight sample than in the ground control. The incidence of abnormality such as the larvae with segmental fusion and the appearance of abnormal crescent marking in the flight sample was significantly higher than that in the ground control. This was also observed in the 1st and 2nd filial generation of the flight sample. From these results, unsuccessful blastokinesis and the abnormal appearance was discussed in relation to cosmic radiation and microgravity.

Space Radiation Organ Doses for Astronauts on Past and Future Missions

by cfynanon 9 June 2015in Biology & Biotechnology No comment

We review methods and data used for determining astronaut organ dose equivalents on past space missions including Apollo, Skylab, Space Shuttle, NASA-Mir, and International Space Station (ISS). Expectations for future lunar missions are also described. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra, or a related quantity, the lineal energy (y) spectra that is measured by a tissue equivalent proportional counter (TEPC). These data are used in conjunction with space radiation transport models to project organ specific doses used in cancer and other risk projection models. Biodosimetry data from Mir, STS, and ISS missions provide an alternative estimate of organ dose equivalents based on chromosome aberrations. The physical environments inside spacecraft are currently well understood with errors in organ dose projections estimated as less than plus or minus 15%, however understanding the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons for which there are no human data to estimate risks. The accuracy of projections of organ dose equivalents described here must be supplemented with research on the health risks of space exposure to properly assess crew safety for exploration missions.

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The ALTEA experiment onboard the International Space Station

by cfynanon 9 June 2015in Biology & Biotechnology No comment

The knowledge of the composition of the radiation environment is an important information for all the radiation safety issues needed for the planning of future long manned space missions. The ALTEA detector is on board the International Space Station since July 2006 and during this period it has performed a detailed measurement of the radiation environment. In this paper we present a summary of past measures and results.

Evaluation of physical and chemical changes in pharmaceuticals flown on space missions

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Efficacy and safety of medications used for the treatment of astronauts in space may be compromised by altered stability in space. We compared physical and chemical changes with time in 35 formulations contained in identical pharmaceutical kits stowed on the International Space Station (ISS) and on Earth. Active pharmaceutical content (API) was determined by ultra- and high-performance liquid chromatography after returning to Earth. After stowage for 28 months in space, six medications aboard the ISS and two of matching ground controls exhibited changes in physical variables; nine medications from the ISS and 17 from the ground met the United States Pharmacopeia (USP) acceptance criteria for API content after 28 months of storage. A higher percentage of medications from each flight kit had lower API content than the respective ground controls. The number of medications failing API requirement increased as a function of time in space, independent of expiration date. The rate of degradation was faster in space than on the ground for many of the medications, and most solid dosage forms met USP standard for dissolution after storage in space. Cumulative radiation dose was higher and increased with time in space, whereas temperature and humidity remained similar to those on the ground. Exposure to the chronic low dose of ionizing radiation aboard the spacecraft as well as repackaging of solid dosage forms in flight-specific dispensers may adversely affect stability of pharmaceuticals. Characterization of degradation profiles of unstable formulations and identification of chemical attributes of stability in space analog environments on Earth will facilitate development of space-hardy medications.

On the radiosensitivity of man in space

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Astronauts' radiation exposure limits are based on experimental and epidemiological data obtained on Earth. It is assumed that radiation sensitivity remains the same in the extraterrestrial space. However, human radiosensitivity is dependent upon the response of the hematopoietic tissue to the radiation insult. It is well known that the immune system is affected by microgravity. We have developed a mathematical model of radiation-induced myelopoiesis which includes the effect of microgravity on bone marrow kinetics. It is assumed that cellular radiosensitivity is not modified by the space environment, but repopulation rates of stem and stromal cells are reduced as a function of time in weightlessness. A realistic model of the space radiation environment, including the HZE component, is used to simulate the radiation damage. A dedicated computer code was written and applied to solar particle events and to the mission to Mars. The results suggest that altered myelopoiesis and lymphopoiesis in microgravity might increase human radiosensitivity in space. c2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Space Radiation Risks for Astronauts on Multiple International Space Station Missions

by cfynanon 9 June 2015in Biology & Biotechnology No comment

Mortality and morbidity risks from space radiation exposure are an important concern for astronauts participating in International Space Station (ISS) missions. NASA’s radiation limits set a 3% cancer fatality probability as the upper bound of acceptable risk and considers uncertainties in risk predictions using the upper 95% confidence level (CL) of the assessment. In addition to risk limitation, an important question arises as to the likelihood of a causal association between a crew-members’ radiation exposure in the past and a diagnosis of cancer. For the first time, we report on predictions of age and sex specific cancer risks, expected years of life-loss for specific diseases, and probability of causation (PC) at different post-mission times for participants in 1-year or multiple ISS missions. Risk projections with uncertainty estimates are within NASA acceptable radiation standards for mission lengths of 1-year or less for likely crew demographics. However, for solar minimum conditions upper 95% CL exceed 3% risk of exposure induced death (REID) by 18 months or 24 months for females and males, respectively. Median PC and upper 95%-confidence intervals are found to exceed 50% for several cancers for participation in two or more ISS missions of 18 months or longer total duration near solar minimum, or for longer ISS missions at other phases of the solar cycle. However, current risk models only consider estimates of quantitative differences between high and low linear energy transfer (LET) radiation. We also make predictions of risk and uncertainties that would result from an increase in tumor lethality for highly ionizing radiation reported in animal studies, and the additional risks from circulatory diseases. These additional concerns could further reduce the maximum duration of ISS missions within acceptable risk levels, and will require new knowledge to properly evaluate.

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Research Containing: Radiation

Stability of chromosome aberrations in the blood lymphocytes of astronauts measured after space flight by FISH chromosome painting

Radiobiological results of the Biostack experiment on board Apollo 16 and 17

Introduction to The Proposed Space Experiments Aboard The ISS Using The Silkworm, Bombyx mori

Targeted Heavy-Ion Microbeam Irradiation of the Embryo But Not Yolk in the Diapause-Terminated Egg of the Silkworm, Bombyx mori, Induces The Somatic Mutation

Embryonic development in the eggs of the silkworm, Bombyx mori, exposed to the space environment

Space Radiation Organ Doses for Astronauts on Past and Future Missions

The ALTEA experiment onboard the International Space Station

Evaluation of physical and chemical changes in pharmaceuticals flown on space missions

On the radiosensitivity of man in space

Space Radiation Risks for Astronauts on Multiple International Space Station Missions