Journal of Radiation Research
Online ISSN : 1349-9157
Print ISSN : 0449-3060
Volume 15, Issue 2
Displaying 1-10 of 10 articles from this issue
  • H. KIMURA
    1974 Volume 15 Issue 2 Pages 75-80
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
    When sea urchin eggs were fertilized with X-irradiated sperm, the prolongation of streak stage in the first cleavage was induced. Caffeine reduced the prolonged streak stage only when the chemical was administered during the period of the prolongation. This effect of caffeine was observed at the concentrations higher than 0.13 mM and reached the maximum at approximately 2 mM. Other methylxanthines such as theophylline and theobromine, which are generally known to increase c-AMP contents in the cell, exhibited similar effects upon the mitotic delay. On the other hand, aminophylline which is also considered to increase c-AMP level in sea urchin eggs, had not such effect.
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  • Y. FUJIWARA, T. KONDO
    1974 Volume 15 Issue 2 Pages 81-89
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
    Two XP cell lines used, XP 1 and XP 3, are defective in unscheduled DNA synthesis and have Do values of 12 and 19 ergs/mm2, respectively. These values are much smaller than the Do of about 100 ergs/mm2 found for HeLa S 3 and human embryonic diploid F 1000 cells. This indicates that excision repair predominates in normal human cells. Mouse L 5 cells possess the reduced ability of unscheduled DNA synthesis which is only one third of that in HeLa and F 1000 cells, but are as UV-resistant as human cells of HeLa and F 1000. This suggests that L 5 cells may possess an enhanced ability of postreplication repair. Molecular evidence for this is that the change with UV dose of the average size of post-UV synthesized DNA pieces in L 5 cells is more similar to that in HeLa cells than that in XP 3 cells. The characteristics of postreplication repair as revealed by alkaline sucrose sedimentation of DNA pieces taken from UV-irradiated human cells (XP, HeLa and F 1000) are as follows : Gaps are formed in newly synthesized DNA and subsequently filled in rather quickly. The gaps fully patched with BrdUrd chase are reformed by photolysis of the BrdUrd patches with near UV irradiation. The gap-filling is prevented by 2 × 10-3M caffeine in human cells as is known for L 5 cells. All the cell lines tested, including two XP lines, show the postreplication repair ability. These results may support a model that the gaps which have been formed in newly synthesized DNA presumably opposite pyrimidine dimers in the parental DNA are filled in by de novo elongation of DNA chains. A possible aspect of UV carcinogenesis in XP is discussed in relation to DNA repair.
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  • F. YATAGAI, T. TAKAHASHI, Y. KITAJIMA, A. MATSUYAMA
    1974 Volume 15 Issue 2 Pages 90-95
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
    Bacillus subtilis spores were bombarded with α-particles and heavy ions of carbon, nitrogen, and oxygen accelerated in the IPCR cyclotron. The maximum RBE was found at an unrestricted LET of about 120 keV·μm-1 The effective inactivation cross section, Seff, for α-particles increased with LET, reaching a stationary level of Sαst, 0.145 μ2. The analysis of the LET dependence revealed that several primary activations are required for producing one lethal-hit, within a very short length of the particle track. The value of Sαst was lower than Seff for heavy ions (0.22 ?? 0.26 μm2). This discrepancy may be due to a difference of the repair capacities of “strand-target” between α-particles and heavy-ion bombardments, or to existence of a target (s) which is sensitive for bombarding particles of extremely high LET, or to a long-range effects caused by such high-LET particles.
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  • T. MATSUNAMI, A. MIZOHATA, T. MAMURO
    1974 Volume 15 Issue 2 Pages 96-102
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
    The isotopic activity ratios of 103Ru to 106Ru and 141Ce to 144Ce in rain water were studied during the period from the end of 1969 to August, 1972. The ratios demonstrated many peaks during the observation period, each of which was likely to resulted from settlement of stratospheric or tropospheric nuclear debris produced by nuclear explosions during the same period.
    The method to distinguish fresh nuclear debris from old debris on the basis of measured radiostrontium activity ratios, developed by Telegadas and Murayama10), was applied to estimate the contributions of the 106Ru and 144Ce produced by a new explosion to the total depositions of these nuclides from the measured activity ratios of 103Ru to 106Ru and 141Ce to 144Ce. The contributions thus estimated ranged from zero to nearly 100 percent, depending on various factors.
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  • F. L. HOFFMAN, V. F. HODGE, T. R. FOLSOM
    1974 Volume 15 Issue 2 Pages 103-106
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
    Polonium-210 radioactivities were measured in organs of 10 oceanic fish from three families. The highest activities were consistently found in the pyloric caecal masses or intestinal contents of these fish.
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  • H. SHIBATA
    1974 Volume 15 Issue 2 Pages 107-110
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
    The time-course of cadmium distribution in mice was investigated for up to 180 days after administration of 109Cd by whole body autoradiography and by radioactivity counting. Accumulated 109Cd was excreted hardly from the body and remained mainly in liver, kidneys and pancreas for a long time. The pattern of retention of 109Cd was varied with organs : in liver, gastrointestinal wall and salivary glands, the concentration of 109Cd was decreased with time; in pancreas, spleen and lungs, it was hardly decreased; in kidneys, it was increased. Liver retained larger amount of 109Cd than any other organ even after long period. In kidneys, most of 109Cd was retained in their cortex.
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  • IZUMI NAKAMURA
    1974 Volume 15 Issue 2 Pages 111-113
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
    When eggs of the sea urchin, Clypeaster japonicus, were fertilized with sperm irradiated with 4 kR X-rays, the first cleavage was delayed about 30 min. In addition, the disappearance of the indent and the end of the streak stage (marked by the disappearance of the nuclear membrane) were delayed by the same length as the first cleavage. From these observations, it is apparent that division delay induced by the irradiation is due to the prolongation of the streak stage.
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  • Y. OKUMURA, Y. UCHIYAMA, K. MORITA
    1974 Volume 15 Issue 2 Pages 114-115
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
    From the analysis of a survival curve, a new significance of the quasi-threshold dose, Dq, was derived. Dq was shown to be the dose at which the decrease in survival per unit dose is maximum.
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  • Y. TAKAGI, M. SHIKITA, S. AKABOSHI
    1974 Volume 15 Issue 2 Pages 116-118
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
    2-Amino-4, 6, 6-trimethyl-1, 3-thiazine and 2-amino-4-methylthiazole demonstrated a radioprotective action in mice irradiated with 70O R of X-rays, but did not show any protective action on radiation-induced killing of cultured HeLa cells. Since no evidence of liberation of SH group through ring opening was observed, the protective action of the compound in mice might be due to its pharmacological action.
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  • Yasukazu Akita
    1974 Volume 15 Issue 2 Pages 119
    Published: June 15, 1974
    Released on J-STAGE: July 14, 2006
    JOURNAL FREE ACCESS
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