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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 1
Displaying 1-6 of 6 articles from this issue
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Special Award Review Articles
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REIKO KANDAArticle type: Others
2000 Volume 41 Issue 1 Pages 1-8
Published: 2000
Released on J-STAGE: July 24, 2001
JOURNAL FREE ACCESSThe frequency of chromosome aberrations in circulating lymphocytes is accepted as being the most reliable indicator of the absorbed dose of radiation. Researches done to improve the accuracy of cytogenetic analysis are described in this review. These include investigations of in vitro factors that affect the yield of radiation-induced aberrations and of in vivo factors that affect the chromosomal radiosensitivity of individuals. Improved chromosome-painting methods for accurate judgment of dicentrics and translocations are introduced. The practicality of these advanced cytogenetic techniques is shown by examinations of individuals exposed in the radiation accident at Tokaimura in 1999.View full abstractDownload PDF (348K) -
HIROSHI TAUCHIArticle type: Others
2000 Volume 41 Issue 1 Pages 9-17
Published: 2000
Released on J-STAGE: July 24, 2001
JOURNAL FREE ACCESSNijmegen breakage syndrome (NBS) is a rare autosomal recessive disorder characterized by microcephaly, combined immunodeficiency, and a high incidence of lymphoid tumor. Cells from NBS patients show chromosomal instability, hypersensitivity to ionizing radiation and abnormal p53-mediated cell cycle regulation. We cloned the underlying gene for NBS, designated NBS1, by complementation-assisted positional cloning from the candidate region 8q21. Large genomic sequencing, as well as a search using computer programs, provides a powerful approach for identifying the underlying gene for a disease. The NBS1 gene encodes a protein of 754 amino acids that has FHA and BRCT domains which often are conserved in cell-cycle checkpoint proteins. The gene has weak homology to the yeast (Saccharomyces cerevisiae) Xrs2 protein in the N-terminus region. Like yeast Xrs2, the NBS1 protein forms a complex with hRAD50/hMRE11, and the complex is condensed as foci in the nucleus after irradiation, indicative that this triple-complex is a crucial factor in DNA repair. Functional analysis of the NBS1 protein is in progress and it should provide further clues to understanding the repair mechanism of radiation-induced DNA double-strand breaks.View full abstractDownload PDF (237K)
Regular Papers
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EZAT ASGARANI, HIROAKI TERATO, KENJIRO ASAGOSHI, HAMID REZA SHAHMOHAMM ...Article type: Regular papers
2000 Volume 41 Issue 1 Pages 19-34
Published: 2000
Released on J-STAGE: July 24, 2001
JOURNAL FREE ACCESSRubrobacter radiotolerans is an extremely radioresistant bacterium. It exhibits higher resistance than the well-known radioresistant bacterium Deinococcus radiodurans, but the molecular mechanisms responsible for the radioresistance of R. radiotolerans remain unknown. In the present study, we have demonstrated the presence of a novel DNA repair enzyme in R. radiotolerans cells that recognizes radiation-induced DNA damages such as thymine glycol, urea residues, and abasic sites. The enzyme was purified from the crude cell extract by a series of chromatography to an apparent physical homogeneity. The purified enzyme showed a single band with a molecular mass of approximately 40 kDa in SDS-polyacrylamide gel electrophoresis, and was designated as R-endonuclease. R-Endonuclease exhibited repair activity for thymine glycol, urea residues, and abasic sites present in plasmid DNA, but did not act on intact DNA, UV-irradiated DNA and DNA containing reduced abasic sites. The substrate specificity together with the salt and pH optima suggests that R-endonuclease is a functional homolog of endonuclease III of Escherichia coli.View full abstractDownload PDF (176K) -
ZHAXYBAY ZHUMADILOV, BORIS I. GUSEV, JUN TAKADA, MASAHARU HOSHI, AKIRO ...Article type: Regular papers
2000 Volume 41 Issue 1 Pages 35-44
Published: 2000
Released on J-STAGE: July 24, 2001
JOURNAL FREE ACCESSFrom 1949 through 1989 nuclear weapons testing carried out by the former Soviet Union at the Semipalatinsk Nuclear Test Site (SNTS) resulted in local fallout affecting the residents of Semipalatinsk, Ust-Kamenogorsk and Pavlodar regions of Kazakstan. To investigate the possible relationship between radiation exposure and thyroid gland abnormalities, we conducted a case review of pathological findings of 7271 urban and rural patients who underwent surgery from 1966-96. Of the 7271 patients, 761 (10.5%) were men, and 6510 (89.5%) were women. The age of the patients varied from 15 to 90 years. Overall, a diagnosis of adenomatous goiter (most frequently multinodular) was found in 1683 patients (63.4%) of Semipalatinsk region, in 2032 patients (68.6%) of Ust-Kamenogorsk region and in 1142 patients (69.0%) of Pavlodar region. In the period 1982-96, as compared before, there was a noticeable increase in the number of cases of Hashimoto's thyroiditis and thyroid cancer. Among histological forms of thyroid cancer, papillary (48.1%) and follicular (33.1%) predominated in the Semipalatinsk region. In later periods (1987-96), an increased frequency of abnormal cases occurred among patients less than 40 years of age, with the highest proportion among patients below 20 in Semipalatinsk and Ust-Kamenogorsk regions of Kazakstan. Given the positive findings of a significant cancer-period interaction, and a significant trend for the proportion of cancer to increase over time, we recommend more detailed and etiologic studies of thyroid disease among populations exposed to radiation fallout from the SNTS in comparison to non-exposed population.View full abstractDownload PDF (50K) -
KIMIO TANAKA, NAILYA J. TCHAIJUNUSOVA, TOSHIHIRO TAKATSUJI, BORIS I. G ...Article type: Regular papers
2000 Volume 41 Issue 1 Pages 45-54
Published: 2000
Released on J-STAGE: July 24, 2001
JOURNAL FREE ACCESSThe Semipalatinsk area is highly contaminated with radioactive fallout from 40 years of continuous nuclear testing. The biological effects on human health in this area have not been studied. Significant remaining radioactivities include long-lived radioisotopes of 238,239,400Pu, 137Cs and 90Sr. To evaluate the long-term biological effects of the radioactive fallout, the incidence of micronuclei in lymphocytes from residents of the area was observed. Blood was obtained from 10 residents (5 females and 5 males, aged 47 to 55 years old) from each of the 3 areas of Znamenka, Dolon and Semipalatinsk, which are about 50-150 km from the nuclear explosion test site. For micronucleus assay, PHA-stimulated lymphocytes were cultured for 72 h and cytochalasin B was added at 44 h for detecting binuclear lymphocytes. Five thousand binuclear lymphocytes in each resident were scored. The means of micronucleus counts in 1,000 lymphocytes in residents of Semipalatinsk, Dolon and Znamenka were 16.3, 12.6, and 7.80, respectively, which were higher than those of the normal Japanese persons (4.66). These values were equivalent to the results obtained from 0.187-0.47 Gy of chronic exposure to γ-rays at a dose rate of 0.02 cGy/min. The high incidence of micronuclei in residents of the Semipalatinsk nuclear test site area was mainly caused by internal exposure rather than external exposure received for the past 40 years.View full abstractDownload PDF (63K) -
MUTSUMI MATSUU, KAZUKO SHICHIJO, YASUKO NAKAMURA, YUJI IKEDA, SHINJI N ...Article type: Regular papers
2000 Volume 41 Issue 1 Pages 55-65
Published: 2000
Released on J-STAGE: July 24, 2001
JOURNAL FREE ACCESSTo evaluate the effect of the sympathetic nervous system on radiation-induced apoptosis in jejunal crypt cells, apoptosis levels were compared in spontaneously hypertensive rats (SHR), animals which are a genetic hyperfunction model of the sympathetic nervous system, and normotensive Wistar-Kyoto rats (WKY). SHR and WKY were exposed to whole body X-ray irradiation at doses from 0.5 to 2 Gy. The apoptotic index in jejunal crypt cells was significantly greater in SHR than in WKY at each time point after irradiation and at each dose. WKY and SHR were treated with reserpine to induce sympathetic dysfunction, and were subsequently exposed to irradiation. Reserpine administration to SHR or WKY resulted in a significant suppression of apoptosis. p53 accumulation was detected in the jejunum in both WKY and SHR after irradiation by Western blotting analysis. There were no significant differences in the levels of p53 accumulation in irradiated intestine between WKY and SHR. These findings suggested that hyperfunction of the sympathetic nervous system is involved in the mechanism of high susceptibility to radiation-induced apoptosis of the jejunal crypt cells.View full abstractDownload PDF (596K)
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