Study on the biological effect of cosmic radiation and the development of radiation protection technology (L-11)

NASDA is now participating in a series of flight experiments on Spacelab missions. The first experiment was carried out on the first International Microgravity Laboratory Mission (IML-1) January 1992, and the second experiment will be conducted on the Spacelab-J Mission, First Materials Processing Test (FMPT). The equipment or Radiation Monitoring Container Devices (RMCD) includes passive dosimeter systems and biological specimens. The experiments using this hardware are designed by NASDA to measure and investigate the radiation levels inside spacecraft like space shuttle and to look at the basic effects of the space environment from the aspect of radiation biology. The data gathered will be analyzed to understand the details of biological effects as well as the physical nature of space radiation registered in the sensitive Solid-State Track Detectors (SSTD)

LET Dependent Recovery of Mouse Hematopoietic Stem Cells from Particle Irradiation

Radiation induced acute changes of mouse heamatopoietic functions and its recovery were studied in different LET of heavy ions, carbon (13keV/mm and 30 keV/mm), neon (32 keV/mm and 55 keV/mm), silicon (56 keV/mm), argon (85 keV/mm) iron (200 keV/mm). After whole body irradiation was applied up to 3 Gy, the subsequent heamatopoietic parameters were followed by the blood analysis for 3 weeks, All functions, spleen weight, WBC, hemoglobin concentration, granulocyte-monocyte colony forming unit (GM-CFU) in bone marrow and spleen indicated dose dependent reduction within 2 days after the irradiation and followed by a slow recovery. Complete recovery took approximately 3 weeks for all functions. GM-CFU in spleen showed the highest sensitivity to all particles indicating a large reduction down to less than 1 % of control at 3 Gy exposured. Of the particle exposed Si (55 keV/mm) induced the largest effects and the slowest recovery, whereas Fe (200 keV/mm) indicated signidicantly the lsast effects and quick recovery. The results suggested a strong LET dependency of the heamatopoietic progenitor cells which may have a RBE maximun less than 100 keV/mm. The recovery kinetics inducated non-monotonic increase within 10 days suggested an involvement of time dependent releases of cytokines (IL-1b ___ IL-3) which may modify the proliferation of hematopoietic cells.12th International Congress of Radiation Researc

Effects of Low Dose Particle Radiation to Mouse Premature Neurons in Culture

Effects of low dose heavy particle radiation to central nervous system (CNS) were studied using mouse neonatal brain cells in culture exposed to heavy ions and X ray at fifth days of the culture. The applied dose varied from 0.05Gy to 2.0Gy. The subsequent biological effects were evaluated by an induction of apoptosis and the survivability of neurons focusing on the dependencies of (1) the animal strains with different genetic types, and (2) LET of the different nucleons. Of the three mouse strains tested, SCID, B6 and C3H, for brain cell culture, SCID was the most sensitive and C3H the least sensitive to both X-ray and carbon ion (290MeV/n) when compared by 10 % apoptotic induction. However, the sensitivity differences among the strains were much smaller in case of carbon ion comparing to that of X-ray. The LET dependency was compared with using C3H and B6 cells exposing to different ions, proton (H, C, Ne, Ar, and Fe). Although no detectable LET dependency was observed at higher dose than 1 Gy, an enhancement was observed in the high LET (85 -200 KeV/_m) and low dose (<0.5 Gy) regions. The survivability profiles of the neurons were different in the mouse strains and ions.14th IAA Humans in Space Symposi