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Volume 31 (1990)
- Issue 4 Pages 311-
- Issue 3 Pages 235-
- Issue 2 Pages 147-
- Issue 1 Pages 97-
Volume 31, Issue 2
Displaying 1-7 of 7 articles from this issue
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FUMIAKI SATO, KAZUO NODA, HIROO KATO, MASAKATSU MURAKAMI, DAIJI ENDOH, ...1990 Volume 31 Issue 2 Pages 147-155
Published: June 15, 1990
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSThe mean life span of animals killed by a specific type of tumor and the incidence of that particular tumor are influenced by competing risks. A parametric approach for censored samples was applied to correct for the competing risks. The life span distribution under each risk wherein the other risks were thought to be eliminated is assumed to be a Weibull distribution. Our data were from an experiment on tumor induction by X-rays in mice: whole body irradiation with 600 R; head with 800 R; trunk with 800 R; or lower body with 800 R. Analysis of the results shows that the mean appearance time of malignant lymphomas was accelerated by whole body irradiation. Acceleration of lung tumors was relatively large after trunk irradiation. Mammary tumors were accelerated by whole body, trunk or lower body irradiation.View full abstractDownload PDF (357K) -
WAKAKO HIRAOKA, MIKINORI KUWABARA, FUMIAKI SATO1990 Volume 31 Issue 2 Pages 156-161
Published: June 15, 1990
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSThe ability of cordycepin to inhibit the repair of DNA strand breaks was examined with X-irradiated Chinese hamster V79 cells in log-phase culture. A filter elution technique revealed that 70 μM cordycepin did not inhibit the repair of single-strand breaks but inhibited the repair of double-strand breaks. These findings confirmed the fact that the increase in the lethality of cordycepin in X-irradiated cultured mammalian cells was attributable to unrepaired DNA double-strand breaks.View full abstractDownload PDF (225K) -
S.P. SINGH, P.C. KESAVAN1990 Volume 31 Issue 2 Pages 162-173
Published: June 15, 1990
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSDry ( ?? 3.5 and 4.0 per cent moisture content) barley seeds were exposed to 350 Gy of 60Co γ-rays in vacuo and post-hydrated at 4°C for 8 h in O2-, N2-, or N2O-saturated water. The effect of caffeine and t-butyl alcohol (t-BuOH) dissolved in the post-hydration medium on the magnitude of damage developing under these three different gaseous circumstances was studied. The post-irradiation damage and its modification by caffeine and t-BuOH was assessed in terms of 8-day-old seedling injury, peroxidase activity and total peroxides in the 8-day-old seedlings.
Post-irradiation O2-saturated hydration caused maximal 8-day-old seedling injury, and increased peroxidase activity with concomitant reduction in total peroxides. Both caffeine and t-BuOH afforded significant radioprotection against post-irradiation O2-dependent damage. Post-irradiation N2O-saturated hydration was even more significantly radioprotective than the N2-saturated post-hydration. Under these circumstances, t-BuOH exerted no effect whatsoever on the N2 and N2O-mediated post-irradiation damage. Caffeine, on the other hand, significantly potentiated these two components of damage.
A brief consideration of the physicochemical events which possibly account for the observed effects is presented.View full abstractDownload PDF (551K) -
SOHEI KONDO1990 Volume 31 Issue 2 Pages 174-188
Published: June 15, 1990
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSThis paper summarizes genetic and somatic data on persons exposed to low doses of atomic bomb radiation in Hiroshima and Nagasaki. Compared with experimental estimates, the new dosimetry system proposed in 1986 underestimates neutron doses, supporting qualitatively the conclusion by the 1965 dosimetry system that Nagasaki A-bomb emitted predominantly gamma rays whereas Hiroshima A-bomb emitted both gamma rays and fast neutrons. A theory based on two recessive mutations in hemopoietic stem cells is proposed to explain radiation leukemogenesis. The theory can explain, at least partly, the actual dose-response curve for incidences of acute leukemia in Hiroshima but cannot explain chronic leukemia in Nagasaki. Existence of a large threshold dose in the latter''s dose relationship supports the hypothesis that A-bomb radiation at high doses above a threshold value was a promoter and/or progressor of leukemia. Various lines of evidence that support this hypothesis are presented. Hence, it is not warranted to assume that risk of death from cancer at a high dose, say, 1 Gy can be divided by 100 to obtain the risk at I cGy. Risk at low doses should be assessed by direct scrutiny of actual data at low doses in spite of their large statistical uncertainty. Actual data show that A-bomb survivors at 1-9 cGy had apparently lower incidences of tumors than unexposed persons.View full abstractDownload PDF (627K) -
YOSHIYA FURUSAWA, KENSHI SUZUKI, MASAKO SASAKI1990 Volume 31 Issue 2 Pages 189-206
Published: June 15, 1990
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSA biological dosimetry system for measuring solar UV-B light was established using bacteriophage T1 with E. coli Bs-1 as the host cell. Also a new physical UV-B dosimeter was developed which can specifically detect the UV spectral region related to inactivation of phage T1.
Phage T1 is very stable in liquid suspension and it has adequate sensitivity to measure the intensity of solar UV-B. In addition, the survival of phage TI responded linearly to UV fluences when plotted semi-logarithmic ally. Thus T1 seemed to have characteristic features making it suitable material as a biological dosimeter for sunlight. Outdoor experiments throughout one year showed that the mean amount of solar UV light in summer was about 6 fold larger than that in winter at Isehara (139.5°E, 35.5°N), Japan.
A novel physical dosimeter which responds faithfully to UV-B light under atmospheric conditions on the ground was developed as well. The spectral response was very close to that of biological materials. Readings of this UV-B dosimeter could be converted into the efficiency of sunlight upon biological materials. This instrument is compact; it can also be used as an erythemal dosimeter.View full abstractDownload PDF (834K) -
TOSHIMASA KIMURA, NAOTO TAKANO, TOSHIYUKI IBA, SHOICHIRO FUJITA, TADAA ...1990 Volume 31 Issue 2 Pages 207-213
Published: June 15, 1990
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSSpecific activity 60Co/Co in two steel samples taken at 687m S and 1295m NNW from the hypocenter was measured by gamma-ray spectrometry and neutron activation analysis. The results were, respectively, (2.64 ± 0.38) × 101 and (3.09 ± 0.48) × 10-1 dpm/mg Co at the time of bombing, which are consistent with previous data by Hashizume et al. for steel rings on the surface of roofs of buildings. The present data are expected to serve as verification of the bomb neutron transport calculations.
Content of nickel and copper in the samples, determined by colorimetric and neutron activation methods, respectively, was too small to account for any significant 60Co production by the (n, p) and (n, α) reactions.View full abstractDownload PDF (232K) -
TAKERU MINAMISAWA, KOUICHI HIROKAGA, SHUNSAKU SASAKI1990 Volume 31 Issue 2 Pages 214-218
Published: June 15, 1990
Released on J-STAGE: June 16, 2006
JOURNAL FREE ACCESSGross morphological changes of the brains of first generation (F1) C57BL/6 × C3H hybrid male mice irradiated prenatally were studied at 6 months of age. Gravid female mice were irradiated with 1.0 Gy, 2.0 Gy or 3.0 Gy of gamma radiation on the 14th day of gestation. The brain in dorsal view was photographed. The measurements of the area and the distance of parts of the brain were made from photographs, using a computer system for biological image analysis. The body and brain weight and the area and length of the cerebral hemispheres (CHs) showed dose-related decrease. There was a dose related increase in the area of the superior colliculi (SC), the distance (DP) from the point which the medial walls of the CHs begin to slope away from the midline to the posterior end of CHs, and the proportion of the DP to the CH length. From the results of the dose-response curve, it appears that the area of the SC and the proportion of DP to CH length are affected by small, doses of less than 1.0 Gy.View full abstractDownload PDF (198K)
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