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Volume 41 (2000)
- Issue 4 Pages 341-
- Issue 3 Pages 201-
- Issue 2 Pages 81-
- Issue 1 Pages 1-
- Issue SUPPL Pages S1-
Volume 41, Issue 2
Displaying 1-9 of 9 articles from this issue
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Regular Papers
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TOMOTAKA SOBUE, VALERIE S. LEE, WEIMIN YE, HIROSHI TANOOKA, MASAAKI MI ...Article type: Regular papers
2000 Volume 41 Issue 2 Pages 81-92
Published: 2000
Released on J-STAGE: July 26, 2001
JOURNAL FREE ACCESSIn order to investigate an association between residential radon exposure and risk of lung cancer, a case-control study was conducted in Misasa Town, Tottori Prefecture, Japan. The case series consisted of 28 people who had died of lung cancer in the years 1976-96 and 36 controls chosen randomly from the residents in 1976, matched by sex and year of birth. Individual residential radon concentrations were measured for 1 year with alpha track detectors. The average radon concentration was 46 Bq/m3 for cases and 51 Bq/m3 for controls. Compared to the level of 24 or less Bq/m3, the adjusted odds ratios of lung cancer associated with radon levels of 25-49, 50-99 and 100 or more Bq/m3, were 1.13 (95% confidence interval; 0.29-4.40), 1.23 (0.16-9.39) and 0.25 (0.03-2.33), respectively. None of the estimates showed statistical significance, due to small sample size. When the subjects were limited to only include residents of more than 30 years, the estimates did not change substantially. This study did not find that the risk pattern of lung cancer, possibly associated with residential radon exposure, in Misasa Town differed from patterns observed in other countries.View full abstractDownload PDF (131K) -
MASANORI TOMITA, NORIO SUZUKI, YOSHIHISA MATSUMOTO, KAZUYA HIRANO, NOR ...Article type: Regular papers
2000 Volume 41 Issue 2 Pages 93-102
Published: 2000
Released on J-STAGE: July 26, 2001
JOURNAL FREE ACCESSHere we found that wortmannin sensitized Chinese hamster V79 cells to hyperthermic treatment at 44.0°C as determined either by colony formation assay or by dye exclusion assay. Wortmannin enhanced heat-induced cell death accompanying cleavage of poly (ADP-ribose) polymerases (PARP). Additionally, the induction of heat shock protein HSP70 was suppressed and delayed in wortmannin-treated cells. Heat sensitizing effect of wortmannin was obvious at more than 5 or 10 μM of final concentrations, while radiosensitization was apparent at 5 μM. Requirement for high concentration of wortmannin, i.e., order of μM, suggests a possible role of certain protein kinases, such as DNA-PK and/or ATM among PI3-kinase family. The sensitization was minimal when wortmannin was added at the end of heat treatment. This was similar to the case of X-ray. Since heat-induced cell death and PARP cleavage preceded HSP70 induction phenomenon, the sensitization to the hyperthermic treatment was considered mainly caused by enhanced apoptotic cell death rather than secondary to suppression or delay by wortmannin of HSP70 induction. Further, in the present system radiosensitization by wortmannin was also at least partly mediated through enhancement of apoptotic cell death.View full abstractDownload PDF (82K) -
YURI MIURA, KAZUNORI ANZAI, JUN-ICHI UEDA, TOSHIHIKO OZAWAArticle type: Regular papers
2000 Volume 41 Issue 2 Pages 103-111
Published: 2000
Released on J-STAGE: July 26, 2001
JOURNAL FREE ACCESSPreviously, we reported that X-irradiation enhanced the signal decay of a spin probe injected into whole mice measured by in vivo ESR, and that the observed enhancement was suppressed by the pre-administration of cysteamine, a radioprotector [Miura, Y., Anzai, K., Urano, S. and Ozawa, T. (1997) Free Rad. Biol. Med. 23: 533-540]. In the present study, the suppression activity of the X-ray-induced increase in the ESR signal decay rate (termed suppression index, SI) was measured for several radioprotectors: 5-hydroxytryptamine (5-HT), S-2-(3-aminopropylamino)-ethylphosphorothioic acid (WR-2721), 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl (TEMPOL), cimetidine, interleukin-1β (IL-1β) and stem cell factor (SCF). The enhancement of the ESR signal decay of carbamoyl-PROXYL due to X-irradiation was suppressed by a treatment with all of the radioprotectors examined, showing positive SI values. However, a dose-dependency of 5-HT or WR-2721 was not observed, suggesting that several mechanisms exist for radioprotection and a modification of the signal decay rate. Although the in vivo ESR system cannot be used in place of the 30-day survival method for the assessment of radioprotectors, this system might be applicable to in vivo, non-invasive screening prior to using the 30-day survival method.View full abstractDownload PDF (58K) -
KAZUO FUJIKAWA, YUKINORI HASEGAWA, SHINYA MATSUZAWA, AKIHIRO FUKUNAGA, ...Article type: Regular papers
2000 Volume 41 Issue 2 Pages 113-127
Published: 2000
Released on J-STAGE: July 26, 2001
JOURNAL FREE ACCESSFollowing the exposure of mice to X rays or fission neutrons, the frequency (F) of apoptosis was measured after 4 h, and the weight loss or lymphocyte content loss in the thymus and spleen was measured after 24 h. In p53(+/+) mice, F increased linearly with the dose (D (Gy)) and the induced rate per Gy of F (detected by TUNEL staining) was 0.05 and 0.23 for X rays and fission neutrons, respectively. Therefore, the RBE of fission neutrons was 4.6 for apoptosis induction. This indicates that radiation-induced apoptosis is mostly due to double strand breaks (DSBs) in DNA because we previously obtained almost the same RBE value of fission neutrons for the induction of crossover mutations in Drosophila melanogaster, which arise from the recombinational repair of DSBs. In p53(+/+) mice, decreases in the organ weight and the lymphocyte content were observed for the thymus and the spleen 24 h after X-irradiation. These atrophic changes in the thymus and the spleen quantitatively corresponded to the total apoptotic cell deaths occurring in them. However, in p53(-/-) mice, no vigorous apoptosis was induced after X-irradiation, and hyperplastic changes in the weight and the lymphocyte content appeared in the thymus and the spleen 24 h after X-irradiation. In p53(+/+) mice, there was no difference in the induced rate per Gy of reduction in the surviving fraction of lymphocytes between acute (0.4 Gy/min) and chronic (3 mGy/min) γ-irradiations. Namely, radiation-induced apoptosis in lymphocytes is a dose-rate independent event.View full abstractDownload PDF (339K) -
YUKO HOSHI, TAKAHARU NOMURA, TAKESHI ODA, TOSHIYASU IWASAKI, KAZUKO FU ...Article type: Regular papers
2000 Volume 41 Issue 2 Pages 129-137
Published: 2000
Released on J-STAGE: July 26, 2001
JOURNAL FREE ACCESSA photoluminescence glass dosimeter, GD-301, was applied to the measurement of low absorbed doses in mice exposed to low-dose rate 137Cs γ-rays. The dosimeter system consists of small rod-shaped glass chip detectors capable of embedded in the body of a mouse and an automatic readout device equipped with a standard detector irradiated with 137Cs γ-source. The measured absorbed doses were compared with the "exposure" estimated by an ionization chamber and with the doses measured by a BeO:Na thermoluminescence system. The results clearly demonstrate the superiority of the glass dosimetry regarding simplicity of operation, stability of long-term dose accumulation and good detector uniformity, which allow accurate tissue dosimetry.View full abstractDownload PDF (74K) -
KAZUKO FUJITA, YOSHIHIKO KAWARADA, KUNIHIKO TERADA, TOSHIHIRO SUGIYAMA ...Article type: Regular papers
2000 Volume 41 Issue 2 Pages 139-149
Published: 2000
Released on J-STAGE: July 26, 2001
JOURNAL FREE ACCESSThe quantitative detection of apoptotic cells in low frequency in the thymus of mice irradiated with X-rays using an anti-single-stranded DNA antibody was explored. The antibody against single-stranded DNA (anti-ssDNA) was obtained with rabbits hyperimmunized with complexes of alkaline-denatured calf thymus DNA. AKR female mice were irradiated with 10 to 100 cGy or 4 Gy X-rays; thereafter, thymus sections were prepared at various times after irradiation. The detection and counting of apoptotic cells in the section were performed after histochemical staining using an anti-ssDNA antibody. The results demonstrate that, although sensitive and quantitative detection of apoptotic cells in irradiated thymus using the anti-ssDNA antibody is possible, the sensitivity is lower compared to that of in situ endlabeling methods, such as TUNEL or ISEL. The antibodies could also be used for rat thymus and spleen. In addition, an increase in positively stained cells by both methods was detected as early as 6 min after the irradiation of mice.View full abstractDownload PDF (547K) -
MINORU TOMIZAWA, TADAAKI MIYAMOTO, HIROTOSHI KATO, HIROSHI OTSUArticle type: Regular papers
2000 Volume 41 Issue 2 Pages 151-161
Published: 2000
Released on J-STAGE: July 26, 2001
JOURNAL FREE ACCESSTo evaluate the acute phase damage to liver by carbon ions, BALB/c mice were irradiated with carbon ions or X-rays after two-thirds partial hepatectomy, and their survival was followed. The 50% lethal dose within 60 days (LD50/60) was 42.2±0.25 Gy (standard error) for X-rays, and 22.7±0.25 Gy for carbon ions. The relative biological effectiveness (RBE) of carbon ions was 1.86 (95% confident limits: 1.69-2.04) as calculated from the LD50/60. Mice irradiated at much higher doses, 60 Gy of X-rays or 24 Gy of carbon ions, showed significantly higher serum ammonia levels and lower serum albumin levels than normal, suggesting hepatic failure as a cause of death. Hepatocytes showed karyorrhexis and karyolysis in carbon ion irradiated and spotty necrosis in X-ray irradiated mice, suggesting nuclear damage. Mice irradiated with LD50 of X-rays or carbon ions had a remarkably lower bromodeoxyuridine (BrdU) labeling index and mitotic index than control. Treatments with both BrdU and vincristine showed that none of the hepatocytes that synthesized DNA after irradiation completed mitosis, indicating G2 arrest. The liver weight of irradiated mice significantly decreased depending on the dose. Carbon ions as well as X-rays damaged hepatocytes directly and suppressed liver regeneration leading to fatal liver failure.View full abstractDownload PDF (67K) -
MIZUHO AOKI, YOSHIYA FURUSAWA, TAKESHI YAMADAArticle type: Regular papers
2000 Volume 41 Issue 2 Pages 163-175
Published: 2000
Released on J-STAGE: July 26, 2001
JOURNAL FREE ACCESSWe investigated the relationship between the LET values and cell death, defined as either apoptosis or loss of reproductive integrity (reproductive death), using Chinese hamster V79 cells. The cells were irradiated with X-rays or carbon-ion beams from the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS). Apoptosis was defined based on the morphological change upon treating of cells with caffeine. The apoptotic index, the ratio of apoptotic cells to the total, after exposure to 2 Gy of X-rays was 0.043. Upon irradiation with carbon-ion beams, the index was gradually increased with increasing LET values, reaching a maximum of 0.076 at 110 keV/μm, and then decreased to 0.054 at 237 keV/μm. An analogous pattern of the LET dependence was observed between reproductive death and apoptotic death. The cell-survival values obtained after 2 Gy exposure (SF2) were 0.64, 0.13, and 0.24, respectively. A similar trend was found for the RBE values calculated from the initial slope for both apoptosis and reproductive death. These results strongly suggest that the target for both types of cell death is the same.View full abstractDownload PDF (226K)
Book Review
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Toshiyasu Hirama, Makoto AkashiArticle type: Reviews
2000 Volume 41 Issue 2 Pages 177-178
Published: 2000
Released on J-STAGE: July 26, 2001
JOURNAL FREE ACCESSDownload PDF (15K)
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