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Volume 30 (1989)
- Issue 4 Pages 323-
- Issue 3 Pages 209-
- Issue 2 Pages 155-
- Issue 1 Pages 112-
Volume 30, Issue 4
Displaying 1-5 of 5 articles from this issue
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MICHIKO ICHIMASA, YUSUKE ICHIMASA, YOSHIMI YAGI, RINKEI KO, MASATOMO S ...1989 Volume 30 Issue 4 Pages 323-329
Published: December 15, 1989
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSThe oxidation of atmospheric molecular tritium (HT) in vegetation was determined by in vitro experiments for pine needles, pine bark, lichens attached to pine trees, taken from a coastal pine forest in Ibaraki prefecture and comparison of such measurements was made with those in soil. The oxidation of HT in pine needles was extremely low, being only about 1/40000 that in the surface soil of a pine forest, whereas its oxidation in pine bark with a lichen was almost 1000-7000 times higher than that in pine needles. HT oxidation in pine bark, a lichen and a moss was determined in each case under light and dark conditions and was found to be essentially the same. All mosses and lichens examined in the present study were found to have unusually high levels of HT oxidation whether their habitat was tree or ground surface.View full abstractDownload PDF (290K) -
MICHIKO ICHIMASA, YUSUKE ICHIMASA, YASUKAZU AKITA1989 Volume 30 Issue 4 Pages 330-337
Published: December 15, 1989
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSIn vivo laboratory experiments on tritium gas (HT) fixation in pine trees were conducted using one-way circuit inhalation apparatus and dwarf pine trees. After 2 hours of exposure to HT, tritium distribution in pine needles, branches, trunk, roots and soil was measured. The specific activity of tritium in pine needles was almost the same as that in the branches and about one fiftieth that in the small roots or soil. To eliminate the contribution of HT oxidation in the soil from the plants, a dwarf pine tree, washed and with its root system sealed, was exposed to HT. Oxidation activity of HT was also determined in in vitro experiments for each part from a dwarf pine tree. Oxidation activity of plant parts above the ground was quite low. In vivo and in vitro experiments were also conducted on dwarf zelkova trees and similar results were obtained.View full abstractDownload PDF (291K) -
Nobuo MUNAKATA1989 Volume 30 Issue 4 Pages 338-351
Published: December 15, 1989
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSSamples of Bacillus subtilis spores dried on membrane filter were exposed to natural sunlight from solarnoon time at Tokyo. The survival and mutation induction of wild-type (UVR) and repair-deficient (UVS) spores were determined on 66 occasions since 1979. Two of the values were considered to be useful in monitoring solar UV intensity; the inverse of the time (in minutes) of exposure to kill 63% of the UVS spores (“sporocidal index”) and the induced mutation frequency at 60 minutes of exposure of the UVR spores (“mutagenic index”). Both values were varied greatly due to time of a year, weather and other conditions. Estimates of year-round changes under clear skies were obtained by connecting the maximum values attained in these years. In these curves, there are more than 7-fold differences in the genotoxicity between winter and summer months, with major increases observed in early spring and decreases through autumn. Using a series of UV cut-off filters, the wavelengths most effective for the sporocidal actions were estimated to be in the range of 308 325 nm, shorter wavelengths being effective when the genotoxicity was higher. Sunburn meter of Robertson-Berger type seems to respond to slightly longer wavelength components of the solar spectrum. However, a reasonable correlation was obtained between the reading of the meter and the sporocidal index.View full abstractDownload PDF (570K) -
KIMIO TANAKA, MIHO TAKECHI, JOEHOON HONG, CHIHARU SHIGETA, NOBUO OGUMA ...1989 Volume 30 Issue 4 Pages 352-358
Published: December 15, 1989
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSTo elucidate the mechanism of leukemia induced by radiation, we studied both chromosome abnormalities and bcr rearrangements of seven CML patients with a history of atomic bomb exposure and 14 CML patients without the exposure. All patients, irrespective of radiation exposure, had 9;22 translocation and rearrangement of the bcr gene in the leukemic cells. Further analysis of breakpoints within the bcr gene demonstrated no distinct difference between the exposed and the non-exposed groups. The present study suggests that formation of the chimeric bcr-abl gene and its genetic products may play an important role in the development of leukemia in either radiation-induced or de novo CML.View full abstractDownload PDF (232K) -
SHOICHIRO FUJITA, HIROO KATO, WILLIAM J. SCHULL1989 Volume 30 Issue 4 Pages 359-381
Published: December 15, 1989
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSData on a total of 7, 593 persons in Hiroshima who were in 2, 518 wooden Japanese houses and exposed to A-bomb within 1.6 km from the hypocenter have been used to estimate the LD50/60. The effect of radiation shielding for these people in particularly well-characterized in the new dosimetry system DS86. A range of values emerge, varying slightly with the method of estimation used. This range, derived from DS86 marrow doses, and based on a linear fit to equally weighted estimates of the probabilities of death at various doses, is 2.3-2.6 Gy. A linear estimate in which the probabilities of death at the various doses are weighted by the inverse of their variances is somewhat lower, 2.2 Gy. These values may be underestimates of actual LD50/60 because of inclusion of deaths in the first day, and the severely injured (burns, trauma) who survived the first day but succumbed later to their injuries.View full abstractDownload PDF (1152K)
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