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Volume 34 (1993)
- Issue 4 Pages 269-
- Issue 3 Pages 195-
- Issue 2 Pages 141-
- Issue 1 Pages 1-
Volume 34, Issue 3
Displaying 1-6 of 6 articles from this issue
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ASHOK KUMAR, HIROSHI KIMURA, TAKASHI AOYAMA1993 Volume 34 Issue 3 Pages 195-203
Published: June 15, 1993
Released on J-STAGE: May 24, 2006
JOURNAL FREE ACCESSRadiosensitization by lactate, pyruvate, nalidixic acid and novobiocin was studied in exponentially growing SH-18L human lung fibroblasts. All the chemicals had a slight radiosensitizing effect at a low concentration and a definite effect at a higher one. Decreases in the D0 and/or Dq values were present in each dose survival curve. Fibroblasts incubated with the low concentration of each chemical for 24 hrs after X irradiation showed no reduction in intracellular ATP content, whereas, the higher concentration produced a significant decrease. These observations suggest that the decrease in the ATP content may be involved in the radiosensitization of human fibroblasts at high concentrations of these chemicals. In contrast, radiosensitization at a low concentration is not explained by a relationship to ATP content. Different mechanisms may be involved in radiosensitization at low and high concentrations of these chemicals.View full abstractDownload PDF (345K) -
MINORU INOUYE, SHIZU HAYASAKA, XUE ZHI SUN, HIDEKI YAMAMURA1993 Volume 34 Issue 3 Pages 204-213
Published: September 15, 1993
Released on J-STAGE: May 24, 2006
JOURNAL FREE ACCESSWe show that neuronal migration is disturbed by low-dose gamma-radiation of 0.24 Gy in the developing cerebral cortex of mice and suggest that neuronal progenitors in the S phase of mitosis are more sensitive than those in the G1 /G0 phase. To pulse-label the fetal cells pregnant Slc : ICR mice were injected with bromodeoxyuridine (BrdU) at 10.00 am on day 16 of pregnancy or at 9.30 am on day 17. The mice then were exposed to 0.24 Gy gamma- or sham-irradiation at 10.00 am on day 17 of pregnancy. At the time of exposure cells labeled on day 16 were regarded as having completed mitosis, and those labeled on day 17 as being in the S phase. Cell death in the fetal ventricular zone after exposure was negligible. Dams were allowed to give birth and rear their litters. Brain samples obtained from offspring on the 2nd day after birth and at 6 weeks of age were used for the immunohistochemical examination of BrdU-labeled cells. Labeled cells remaining in the ventricular zone were significantly more numerous in irradiated animals than in sham-exposed ones on the 2nd day after birth, in mice treated prenatally with BrdU on day 17 of pregnancy; whereas, mice treated with BrdU on day 16 showed no statistically significant difference. At 6 weeks of age, in both groups most of the labeled cells were present in layers II-III of the SmI cerebral cortex. But, in the irradiated animals the labeled cells in these layers were significantly fewer and those in layers IV-VI more numerous than in the sham-exposed mice in both group treated with BrdU on day 16 or 17.View full abstractDownload PDF (759K) -
Y. MURAMATSU, S. UCHIDA, Y. OHMOMO1993 Volume 34 Issue 3 Pages 214-220
Published: September 15, 1993
Released on J-STAGE: May 24, 2006
JOURNAL FREE ACCESSRoot-uptake of iodine by rice plants from two different soil types was studied using an 125I tracer. At harvest, the 125I concentration was lowest in brown rice (hulled rice) followed by the rachis, stem and leaves. The transfer factors of iodine for brown rice grown on Andosol and Gray lowland soil (fine texture) respectively were 0.007 and 0.002. The ratio of the radioiodine concentrations between flag leaf (first leaf blade) and brown rice was about 400. Transfer factors in plants grown on Andosol were higher than those grown on Gray lowland soil. This may be related to the high 125I concentration in the Andosol soil solutions, particularly after the flowering period. The adsorption and desorption of iodine in the soil was effected by flooding with water and also by the cultivation of rice plants. The radioiodine concentration in the soil solutions first increased in the upper soil layer then in the lower layer. The desorption pattern of iodine was influenced by the soil types.View full abstractDownload PDF (290K) -
MIROSLAV PINAK, AKIRA ITO1993 Volume 34 Issue 3 Pages 221-234
Published: September 15, 1993
Released on J-STAGE: May 24, 2006
JOURNAL FREE ACCESSThe Monte Carlo simulation of energy deposition in structural parts of DNA based on “Structural Model” is described. This model takes under consideration space positions of atoms in B-form of DNA and clearly defines sensitive volumes of each nucleotide (phosphodiester bonds, sugar, base, hydrogen bonds). ETRACK code producing the positions of energy deposition events in water vapor medium is used for simulation of electron track structure. The electron production points are chosen randomly within the sphere containing cell nucleus. DNA segments are randomly distributed in cell nucleus. Each energy deposition point is tested if it occurs in any element of any DNA part. The highest probability of energy deposition is found for phosphodiester bonds area, whereas the lowest for deoxyribose area. Electrons of initial energies from 5 keV to 10 keV have higher probability of energy deposition in structural part in comparison with lower and higher energy electrons.View full abstractDownload PDF (527K) -
HIROMITSU WATANABE, TARO OKAMOTO, KAZUMASA YAMADA, YASUMI ANDO, AKIHIR ...1993 Volume 34 Issue 3 Pages 235-239
Published: September 15, 1993
Released on J-STAGE: May 24, 2006
JOURNAL FREE ACCESSThe effects of the dose rate and the energy of fission neutrons using an iron block on tumorigenesis in B6C3F1 mice were examined. Six-week-old female animas were divided into 4 groups and exposes to 252Cf neutron irradiation at dose rates of 0.05 cGy/min, with (Group 1) or without (Group 2) filtering through a 10 cm thick iron block, 0.8 cGy/min (Group 3) or 0 (Group 4 controls). Total neutron exposure was 50 cGy in each of groups 1-3 and total irradiation dose was 56, 75 and 75 cGy in Groups 1-3, respectively. Total tumor incidences or multiplicity were significantly higher in Group 3 than in Group 1. A similar tendency was observed as compared to Group 2, ovarian and Harderian gland tumors being mainly affected and adrenal tumors were significantly higher in Group 2 than in Group 1. The results indicated a clear increase in tumorigenesis with the higher dose rate and no filtering influence of iron was evident, despite the drop in neutron energy level.View full abstractDownload PDF (210K) -
YIN QUAN ZHANG, ZUEN TAO XU, MAN LO YU1993 Volume 34 Issue 3 Pages 240-246
Published: September 15, 1993
Released on J-STAGE: May 24, 2006
JOURNAL FREE ACCESSThe carcinogenic effects of solar activity with different intensities on embryos were studied epidemiologically. The study reveals that receiving a moderate amount of low level cosmic radiation at embryonic stage may reduce cancer occurrence later. This paper analyses and discusses the mechanisms of this hormetic effect.View full abstractDownload PDF (345K)
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