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Volume 40 (1999)
- Issue 4 Pages 303-
- Issue 3 Pages 223-
- Issue 2 Pages 95-
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Volume 40, Issue 3
Displaying 1-6 of 6 articles from this issue
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Short Communication
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JUN TAKADA, VARELY E. STEPANOV, DANIEL P. YEFREMOV, TAKAHIRO SHINTANI, ...Article type: Short communications
1999 Volume 40 Issue 3 Pages 223-228
Published: 1999
Released on J-STAGE: June 04, 2001
JOURNAL FREE ACCESSA radiological survey around the site of Kraton-4, an underground nuclear explosion (Yield of 20 kt, depth of 560 m, 1978) in Sakha was carried out in March 1998. Gamma survey and in-situ spectroscopy on the ground exhibited quite normal levels: a dose rate of 0.022 μSv/h and Cs-137 surface contamination of less than 1.1 kBq/m2 around the hypocenter. The results suggested no remarkable leakage of radioactivity from the epicenter to the ground surface at least not for non-rare gas elements as of 1998.View full abstractDownload PDF (407K)
Regular Paper
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SHUNSAKU SASAKI, NOBUO FUKUDAArticle type: Regular papers
1999 Volume 40 Issue 3 Pages 229-241
Published: 1999
Released on J-STAGE: June 04, 2001
JOURNAL FREE ACCESSOur previous studies showed that mice during infancy are highly susceptible to the induction of several types of solid tumors. The present study was designed to elucidate the dose-response relationships for induction of solid tumors after exposure to 0.48-5.70 Gy of 137Cs gamma rays in the neonatal period in female mice. A total of 2988 mice were allowed to live out their life span under a specific pathogen free condition and lifetime incidences of liver, pituitary, ovarian, lung and bone tumors were recorded. The dose-response curves for liver, pituitary, ovarian and lung tumors were convex upward in the dose range examined, and were composed of three parts: an initial rapid increase of incidence at doses below 1 Gy, a gradual increase to the highest incidence, and a decrease in incidence with increasing dose in the higher dose range. The dose which induces neoplasm at the highest incidence seemed to be different for each type of solid tumor. The shape of the dose-response curve for induction of bone tumors was quite different from that for other solid tumors; the initial slope of the curve was concave upward. Dose-response relationships were analyzed using a model that allows for tumorigenic effect, inactivation of potentially tumorigenic cells and competing risks. The results showed that the tumorigenic effect was proportional to the dose of gamma rays for induction of liver, pituitary, ovarian and lung tumors; whereas the tumorigenic effect for bone tumors was proportional to the square of the dose. A significant increase in incidence was also found for gastrointestinal tumors, kidney tumors, adrenal tumors and hemangiomas of spleen, although dose-response relationships could not be analyzed.View full abstractDownload PDF (69K) -
MICHIKO ICHIMASA, MASATOMO SUZUKI, HARUO OBAYASHI, YOUICHI SAKUMA, YUS ...Article type: Regular papers
1999 Volume 40 Issue 3 Pages 243-251
Published: 1999
Released on J-STAGE: June 04, 2001
JOURNAL FREE ACCESSTo quantify the rate of oxidation of tritium gas (referred to as HT) to tritiated water in the environment, various woody and herbaceous plant leaves and roots, mosses and lichens taken from a forest and fields in Ibaraki prefecture, and a forest in Toki, Gifu prefecture, were investigated as to their ability to oxidize atmospheric HT in in vitro experiments. The HT oxidation activity in vegetation was compared with that in the surrounding surface soil (0-5 cm in depth). The rate of oxidation of HT in woody plant leaves including pine needles was extremely low, only about 1/10000-1/1000 that in the surface soil, as well as in herbaceous plant leaves with some exceptions (Phalaris arundinacea and Vaccinium smallii), whereas the rate in mosses and lichens was 50-500 times that in pine needles. The HT oxidation activity in roots of several plants including Phalaris arundinacea, Pieris japonica and Lespedeza homoloba was quite high and comparable to that in the surrounding surface soil. These results suggest that mosses, lichens and the leaves or roots of particular plants with high HT oxidation activity can be used to monitor the accidental release of HT into the environment.View full abstractDownload PDF (51K) -
YUKO IBUKI, RENSUKE GOTOArticle type: Regular papers
1999 Volume 40 Issue 3 Pages 253-262
Published: 1999
Released on J-STAGE: June 04, 2001
JOURNAL FREE ACCESSThe activation mechanism of resident peritoneal macrophages by in vivo γ-irradiation was investigated. The function of macrophages as accessory cells in concanavalin A-induced proliferation of spleno-lymphocytes (accessory function) was enhanced 4 h after a low-dose irradiation (4 cGy) in vivo, but not in vitro, indicating that low-dose irradiation acts indirectly on the activation of macrophages. Because we expected that macrophages were activated by the recognition of substances damaged by in vivo irradiation, we co-cultured macrophages with oxidized erythrocyte-ghosts. No change was found in their accessory function. The production of inflammatory cytokines, interleukin-1β (IL-1β) and interferon-γ (IFN-γ), in the supernatant of cocultures of spleno-lymphocytes and macrophages was determined by an ELISA. Production of both increased in the presence of in vivo irradiated macrophages. Furthermore, IL-1β production from in vivo-irradiated macrophages treated with recombinant IFN-γ also was enhanced. The mRNA expression of the cytokines released from macrophages and lymphocytes was determined by RT-PCR. Increases in IL-1β mRNA expression were found in both in vivo- and in vitro-irradiated macrophages. In vivo irradiation also enhanced the expression of IFN-γ mRNA in lymphocytes, whereas there was no change after in vitro irradiation. On the basis of these observations, we propose that the activation of macrophages is caused by interaction with neighboring cells, such as lymphocytes, and by paracrine induction of certain cytokines which is initiated by the small amount of IL-1β released by irradiated macrophages.View full abstractDownload PDF (127K) -
YANJUN LU, TAKASHI YAGIArticle type: Regular papers
1999 Volume 40 Issue 3 Pages 263-272
Published: 1999
Released on J-STAGE: June 04, 2001
JOURNAL FREE ACCESSOne of the major factors for efficacy of a chmotherapeutic drug is its activity to induce apoptosis of tumor cells. Doxorubicin and daunorubicin, radiomimetic anthracycline-group drugs, have been used for chemotherapy for about 30 years. Here we established the colorectal tumor and osteosarcoma cells in which Bax expression can be induced by the treatment of isopropyl-β-D-thiogalactopyranoside, and examined the effect of the Bax overexpression on the cell death caused by these drugs. While the Bax overexpression neither affected growth nor morphology of the undamaged cells, it enhanced the cell death caused by these drugs. Increase in cellular nucleus fragmentation and DNA ladder formation indicates that the Bax-enhanced cell death is due to enhanced apoptosis of the drug-treated cells. The enhanced cell death was not observed when the cells were irradiated with X-ray or treated with other chemotherapeutic agents we examined. These results indicate that Bax may have a specific role to enhance the efficacy of chemothrapy with anthracycline-group agents.View full abstractDownload PDF (96K) -
MIN-JEONG YI, TAE-HWAN KIM, SU-JAE LEE, CHUL-KOO CHO, IN-HWA BAE, YUN- ...Article type: Regular papers
1999 Volume 40 Issue 3 Pages 273-284
Published: 1999
Released on J-STAGE: June 04, 2001
JOURNAL FREE ACCESSThe aim of this study was to determine whether γ-rays affect differentiation in mouse epidermal cells. After a pre-treatment with the PKC inhibitor staurosporin (STS) or 1-(5-isoquinolinesulfomyl)-2-methylpiperazine (H7), γ-rays were irradiated with or without an elevation of 0.12 mM Ca2+ and expressions of differentiation markers and each PKC isozyme were examined in normal primary and v-rasHa transformed mouse keratinocytes. Gamma-rays induced the expressions of differentiation markers of keratin 1 and 10 (K1 and 10), filaggrin, loricrin and SPR-1 in normal keratinocytes when the Ca2+ concentration was increased, and these phenomena were augmented in H7 pretreated cells. Similar results were obtained in STS pretreated cells; in this case, γ-rays enhanced the expressions of the differentiation markers even without an elevated Ca2+ concentration. In v-rasHa transformed cells, γ-rays induced the expression of differentiation markers not only at 0.05 mM Ca2+, but in 0.12 mM Ca2+-shifted cells, and in H7 pretreated cells, these phenomena were augmented. The translocation of PKCα to the particulate fraction was seen in H7 pretreated normal keratinocytes. Radiation also induced PKCα expression in STS pretreated cells, independent of Ca2+-shift, as well as altered expressions of PKC δ and -η, while expressions of PKCα, -δ, -ε, and -η were enhanced in v-rasHa transformed cells. In conclusion, γ-rays augmented the expressions of both spinous and granular differentiation markers in normal and v-ras Ha transformed keratinocytes and this effect was augmented when PKC inhibitors were used, which may be mediated by the cellular redistribution of PKC isozymes.View full abstractDownload PDF (122K)
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