著者

大竹 正徳 WILLIAM J. SCHULL

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.32, no.SUPPLEMENT, pp.283-293, 1991 (Released:2006-05-31)

参考文献数

38

被引用文献数

9 20

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This report reviews the relationship of ionizing radiation to the occurrence of cataracts (posterior lenticular opacities) among the A-bomb survivors in Hiroshima and Nagasaki. The new DS86 doses are available for 1, 983 (93.4%) of the 2, 124 A-bomb survivors analyzed in 1982. The DS86 kerma neutron component for Hiroshima is much smaller than its comparable T65DR component, but still 4.2 fold higher (0.38 Gy at 6 Gy) than that in Nagasaki (0.09 Gy at 6 Gy). Thus, if the eye is especially sensitive to neutrons, there may yet be some useful information on their effects, particularly in Hiroshima. Under the best fitting dose-response model, an L(gamma)-L(neutron) with two thresholds, both the gamma and neutron regression coefficients of the occurrence of cataracts on dose are positive and highly significant for the DS86 eye organ doses. The DS86 gamma coefficient is almost the same as that associated wih the T65DR gamma dose, the ratio of the two coefficients being 1.1 (95% confidence limits: 0.5-2.3) for DS86 kerma in the individual dose data, and if the risks based on the DS86 eye organ dose and DS86 kerma are compared, the ratio is 1.3 (0.6-2.8). However, the risk estimates associated with neutron exposure are 6.4 (2.2-19.2) fold higher for the DS86 kerma than the T65DR kerma and 1.6 (0.5-2.3) fold higher for the DS86 eye organ dose than for the DS86 kerma.

著者

JUN TAKADA MASAHARU HOSHI SHOZOH SAWADA MASANOBU SAKANOUE

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.24, no.3, pp.229-236, 1983-09-15 (Released:2006-06-16)

参考文献数

14

被引用文献数

9 11 9

---

Uranium isotopes were studied to clarify the fallout from the Hiroshima atomic bomb. The 234U/238U activity ratios of uranium leached from the soil in the Hiroshima fallout area were significantly higher than those of other areas according to alpha ray spectrometry. The correlation of specific activity of the fission product 137Cs and the 234U/238U activity ratios was studied. Two different correlations were established inside and outside the fallout area. The results of this study suggest that manifestations of fallout from the Hiroshima atomic bomb are still detectable in the “black rain” area.

著者

Deborshi BHATTACHARJEE Alexander I. IVANNIKOV Kassym ZHUMADILOV Valeriy F. STEPANENKO Kenichi TANAKA Satoru ENDO Megu OHTAKI Shin TOYODA Joyeeta BHATTACHARYYA Masaharu HOSHI

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.50, no.6, pp.559-565, 2009 (Released:2009-12-04)

参考文献数

24

---

Electron spin resonance (ESR) dosimetry of teeth is used extensively for dose estimation following exposure to radiation. The population inhabiting the northeast region of India is prone to different cancers of the head and neck, and their prevalence is several times the national average. The objective of this study was to determine the role of radiation in the causation of this high cancer incidence by performing ESR spectroscopic measurements of tooth samples collected from the general population living in and around the city of Silchar. Nineteen tooth samples were used, and the age of the patients was 13-60 years. The excess dose, determined by subtraction of the natural background dose from the dose absorbed by the enamel, was found to the extent of 123 ± 43 mGy. However, the individual excess dose was found to be higher in subjects who consumed lime (5/6) than in non-lime-consuming subjects (2/13). It is not entirely clear if radiation is the cause of this excess cancer in this region of India. Therefore there is a need for wider studies including consideration of tobacco consumption as well as a larger number of samples for tooth enamel dosimetry.

著者

Dinara ZHARLYGANOVA Hironori HARADA Yuka HARADA Sergey SHINKAREV Zhaxybay ZHUMADILOV Aigul ZHUNUSOVA Naylya J. TCHAIZHUNUSOVA Kazbek N. APSALIKOV Vadim KEMAIKIN Kassym ZHUMADILOV Noriyuki KAWANO Akiro KIMURA Masaharu HOSHI

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.49, no.5, pp.549-555, 2008 (Released:2008-09-19)

参考文献数

33

被引用文献数

18

---

It is known that bone marrow is a sensitive organ to ionizing radiation, and many patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) have been diagnosed in radiation-treated cases and atomic bomb survivors in Hiroshima and Nagasaki. The AML1/RUNX1 gene has been known to be frequently mutated in MDS/AML patients among atomic bomb survivors and radiation therapy-related MDS/AML patients. In this study, we investigated the AML1 mutations in radiation-exposed patients with MDS/AML among the residents near the Semipalatinsk Nuclear Test Site (SNTS), where the risk of solid cancers and leukemias was increased due to the radiation effects. AML1 mutations were identified in 7 (39%) of 18 radiation-exposed MDS/AML patients. In contrast, no AML1 mutation was found in 13 unexposed MDS/AML cases. The frequency of AML1 mutations in radiation-exposed patients with MDS/AML was significantly higher compared with unexposed patients (p < 0.05).We also found a significant correlation between individual estimated doses and AML1 mutations (p < 0.05). Considering these results, AML1 point mutations might be a useful biomarker that differentiates radio-induced MDS/AML from spontaneous MDS/AML.

著者

Zhaxybay ZHUMADILOV

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.47, no.SupplementA, pp.A183-A187, 2006 (Released:2006-03-28)

参考文献数

12

被引用文献数

2

---

The risk of radiation-induced nodules is higher than the risk for radiation-induced cancer. Risk factors and specific modifiers of the dose-response relationship may vary among different populations and not be well recognized. Many thyroid studies have considered thyroid nodularity itself, but not specific morphological types of thyroid nodules. There are many specific types of thyroid nodules which follow a morphological classification of thyroid lesions, including some congenital and tumor-like conditions. Modern equipment and technique can help us to identify particular specific types of thyroid nodules. In this study we report some results of a clinically applicable approach to materials derived from three studies. From 1999 through 2002, we have screened 571 current residents from 4 exposed and 1 control village near the Semipalatinsk Nuclear Test Site area, who were of similar ages (<20) at the time of major radiation fallout events at the SNTS. Prevalent nodules were identified by ultrasound and fine-needle aspiration biopsy, cytopathology results. Analysis of ultrasound images and cytopathology of thyroid lesions among exposed and non-exposed population allowed us to distinguish some interesting ultrasound features for specific types of thyroid nodules. We believe that it would be interesting and possibly more informative for thyroid dosimetry studies to consider specific morphological types of thyroid nodules. We need more detailed research to clarify the feasibility of applying these findings for study of the dose-response relationship.

著者

Sobue Tomotaka Lee Valerie S. Ye Weimin TANOOKA HIROSHI MIFUNE MASAAKI SUYAMA AKIHIKO KOGA TAEKO MORISHIMA HIROSHIGE KONDO SOHEI

出版者

日本放射線影響学会

雑誌

Journal of radiation research (ISSN:04493060)

巻号頁・発行日

vol.41, no.2, pp.81-92, 2000-06

被引用文献数

3 17

---

In 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.

著者

Yamamoto Tetsuo Kinoshita Manabu Shinomiya Nariyoshi HIROI Sadayuki SUGASAWA Hidekazu MATSUSHITA Yoshitaro MAJIMA Takashi SAITOH Daizoh SEKI Shuhji

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of radiation research (ISSN:04493060)

巻号頁・発行日

vol.51, no.2, pp.145-156, 2010-03-16

被引用文献数

38

---

While bone marrow or stem cell transplantation can rescue bone marrow aplasia in patients accidentally exposed to a lethal radiation dose, radiation-induced irreversible gastrointestinal damage (GI syndrome) is fatal. We investigated the effects of ascorbic acid on radiation-induced GI syndrome in mice. Ascorbic acid (150 mg/kg/day) was orally administered to mice for 3 days, and then the mice underwent whole body irradiation (WBI). Bone marrow transplantation (BMT) 24 h after irradiation rescued mice receiving a WBI dose of less than 12 Gy. No mice receiving 14 Gy-WBI survived, because of radiation-induced GI syndrome, even if they received BMT. However, pretreatment with ascorbic acid significantly suppressed radiation-induced DNA damage in the crypt cells and prevented denudation of intestinal mucosa; therefore, ascorbic acid in combination with BMT rescued mice after 14 Gy-WBI. DNA microarray analysis demonstrated that irradiation up-regulated expressions of apoptosis-related genes in the small intestine, including those related to the caspase-9-mediated intrinsic pathway as well as the caspase-8-mediated extrinsic pathway, and down-regulated expressions of these genes in ascorbic acid-pretreated mice. Thus, pretreatment with ascorbic acid may effectively prevent radiation-induced GI syndrome.

著者

遠藤 暁 HOSHI M. TAUCHI H. TAKEOKA S. KITAGAWA K. SUGA S. MAEDA N. KOMATSU K. SAWADA S. IWAMOTO B. SAKAMOTO S. TAKEYAMA K. OMURA M.

出版者

日本放射線影響学会

雑誌

Journal of radiation research (ISSN:04493060)

巻号頁・発行日

vol.36, no.2, pp.91-102, 1995-06

参考文献数

13

被引用文献数

10 24

---

A neutron generator (HIRRAC) for use in radiobiology study has been constructed at the Research Institute for Radiation Biology and Medicine, Hiroshima University (RIRBM). Monoenergetic neutrons of which energy is less than 1.3 MeV are generated by the ^7Li(p,n)^7Be reaction at proton energies up to 3 MeV. The protons are accelerated by a Schenkel-type-accelerator and are bombared onto the ^7Li-target. An apparatus for the irradiation of biological material such as mice, cultured cells and so on, was designed and will be manufactured. Neutron and gamma-ray dose rates were measured by paired (TE-TE and C-GO2) ionization chambers. Contamination of the gamma ray was less than about 6% when using 10-dum-thick ^7Li as a target. Maximum dose rates for the tissue equivalent materials was 40 cGy/min at a distance of 10 cm from the target. Energy distributions of the obtained neutrons have been measured by a ^3He-gas proportion-al counter. The monoenergetic neutrons within an energy region from 0.1 to 1.3 MeV produced by thin ^7Li or ^7LiF targets had a small energy spread of about 50 keV (1 Gσ width of gaussian). The energy spread of neutrons was about 10% or less at an incident proton energy of 2.3 MeV. We found that HIRRAC produces small energy spread neutrons and at sufficient dose rates for use in radiobiology studies.

著者

Ban-nai Tadaaki Muramatsu Yasuyuki Yoshida Satoshi

出版者

日本放射線影響学会

雑誌

Journal of radiation research (ISSN:04493060)

巻号頁・発行日

vol.45, no.2, pp.325-332, 2004-06-15

被引用文献数

1 13

---

Mushrooms are known to accumulate radiocesium. To estimate the intake of radiocesium through the eating of mushrooms, about 30 samples belonging to 4 commonly consumed species (Lentinula edodes, Hyp-sizigus marmoreus, Grifola frondosa, and Tricholoma matsutake), were analyzed for ^<137>Cs and 40K. The concentration ranges were 0.060-29 Bq kg^<-1> (wet wt) for ^<137>Cs and 38-300 Bq kg^<-1> (wet wt) for ^<40>K. The geometric mean concentration for ^<137>Cs was 0.56 Bq kg^<-1> (wet wt), and the mean concentration for ^<40>K was 92 Bq kg^<-1> (wet wt). The ^<137>Cs concentrations in L. edodes cultivated in mushroom beds (sawdust-rice bran media) were lower than those cultivated on bed logs (natural wood with bark). The annual intake of ^<137>Cs per person through mushrooms was calculated, by using the current analytical results and food consumption data in Japan, to be 3.1 Bq for ^<137>Cs, which is about 28% of the total dietary intake of this nuclide. The effective dose equivalent of ^<137>Cs through mushrooms was estimated to be 4.0×10^<-8> Sv, which is about the half the value obtained in our previous study. The decrease of the ^<137>Cs intake through mushrooms is probably related to changes in cultivation methods in recent years, from the use of bed logs to mushroom beds.

著者

望月 肇 賀田 恒夫

出版者

日本放射線影響学会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.23, no.3, pp.403-410, 1982-09

被引用文献数

4

---

We formerly showed that human placenta contained strong antimutagenic factors working on radiation and chemically induced mutations in bacteria We are actually examining, in several aspects, if these factors might have certain physiological functions in mammals or not. In this communication, we report that our preparations made from the human placenta tissues greatly restore lethal injuries in X-ray-irradiated mice. Three placenta specimens of healthy women were obtained from the Shimada Hospital (Mishima City). Each tissue was first washed with aqueous KCl (0.15 M) solution, homogenized without any supplementation and centrifuged at 14,000 x g for 20 minutes. The supernantant was then treated with 20 μig/ml pronase at 370C for 20 minutes, followed by dialysis overnight in distilled water. The dialysate was then heated in boiling water for 30 minutes to denature proteic constituents and centrifuged at 3000 x g for 20 minutes. The cellular supernatant solution in a total volume of 10 ml was loaded first on a column (2×20 cm) of Amberlite IR-120B resin and the column was eluted with 500 ml of distilled water.

著者

Shiga Takeki Suzuki Hiroyuki Yamamoto Ayumi YAMAMOTO Hiroaki YAMAMOTO Kazuo

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of radiation research (ISSN:04493060)

巻号頁・発行日

vol.51, no.4, pp.405-415, 2010-07-16

被引用文献数

1 12

---

Previously, we have shown that phenyl hydroquinone, a hepatic metabolite of the Ames test-negative carcinogen <i>o</i>-phenylphenol, efficiently induced aneuploidy in <i>Saccharomyces cerevisiae</i> by arresting the cell cycle at the G2/M transition as a result of the activation of the Hog1 (p38 MAPK homolog)-Swe1 (Wee1 homolog) pathway. In this experiment, we examined the aneuploidy forming effects of hydroquinone, a benzene metabolite, since both phenyl hydroquinone and hydroquinone are Ames-test negative carcinogens and share similar molecular structures. As was seen in phenyl hydroquinone, hydroquinone induced aneuploidy in yeast by delaying the cell cycle at the G2/M transition. Deficiencies in <i>SWE1</i> and <i>HOG1</i> abolished the hydroquinone-induced delay at the G2/M transition and aneuploidy formation. Furthermore, Hog1 was phosphorylated by hydroquinone, which may stabilize Swe1. These data indicate that the hydroquinone-induced G2/M transition checkpoint, which is activated by the Hog1-Swe1 pathway, plays a role in the formation of aneuploidy.

著者

小松 賢志 樋口 昌孝 粟冠 正利

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.22, no.2, pp.226-241, 1981-07-15 (Released:2006-06-16)

参考文献数

38

被引用文献数

11

---

Accumulation of tritium in aquatic organisms was estimated through a model food chain such as; tritiated water (THO) → diatoms → brine shrimps → Japanese killifish. Tritium accumulations in each organism as organic bound form are expressed as the R value which is defined as the ratio of tritium specific activity in lyophilized organisms (μCi/gH) to that in water (μCi/gH). The maximum R values were 0.5 in diatoms, Chaetoceros gracilis, 0.5 in brine shrimps, Artamia salina, and 0.32 in Japanese killifish, Oryzias latipes under the growing condition where tritium accumulation took place from tritiated water without tritiated diets. Brine shrimps and Japanese killifish, which grew from larvae to adult in tritiated sea water with feeding on tritiated diets (model food chain), had the R value at 0.70 and 0.67 respectively, indicating that more tritium accumulation in consumer populations with tritiated diets than those without tritiated diets. In addition, the R values of each organ of Japanese killifish, of DNA and the nucleotides purified rfom brine shrimps growing under the condition with or without our model food chain were measured to estimate the tritium distribution in the body or various components of the organism. These results did not indicate the seeking characteristic of tritium to some specific organs of compounds.

著者

TAKEO OHNISHI KEN OHNISHI AKIHISA TAKAHASHI YOSHITAKA TANIGUCHI MASARU SATO TAMOTSU NAKANO SHUNJI NAGAOKA

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.43, no.S, pp.S133-S136, 2002 (Released:2003-05-02)

参考文献数

7

被引用文献数

20

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Although physical monitoring of space radiation has been accomplished, we aim to measure exact DNA damage as caused by space radiation. If DNA damage is caused by space radiation, we can detect DNA damage dependent on the length of the space flight periods by using post-labeling methods. To detect DNA damage caused by space radiation, we placed fixed human cervical carcinoma (HeLa) cells in the Russian Mir space station for 40 days and in an American space shuttle for 9 days. After landing, we labeled space-radiation-induced DNA strand breaks by enzymatic incorporation of [3H]-dATP with terminal deoxyribo-nucleotidyl transferase (TdT). We detected DNA damage as many grains on fixed silver emulsion resulting from β-rays emitted from 3H-atoms in the nuclei of the cells placed in the Mir-station (J/Mir mission, STS-89), but detected hardly any in the ground control sample. In the space shuttle samples (S/MM-8), the number of cells having many grains was lower than that in the J/Mir mission samples. These results suggest that DNA damage is caused by space radiation and that it is dependent on the length of the space flight.

著者

Muzahir Ali BALOCH Aziz Ahmed QURESHI Abdul WAHEED Muhammad ALI Nawab ALI Muhammad TUFAIL Saima BATOOL Muhammad AKRAM Poonam IFTIKHAR Hamza QAYYUM Shahid MANZOOR Hameed Ahmed KHAN

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.53, no.3, pp.411-421, 2012 (Released:2012-06-01)

参考文献数

55

被引用文献数

20

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The Khewra Salt Mines, the second largest salt mines in the world, are located 160 km south of Islamabad, the capital of Pakistan. Around 1000 workers are involved in the removal of salt from these mines. More than 40,000 visitors come annually to see the mines. The visitors and workers are directly exposed to the internal and external radiological hazards of radon and gamma rays in these mines. The general public is affected by the intake of the salt containing the naturally occurring radionuclides. Therefore the concentration of radon (222Rn) in the Khewra Salt Mines and activity concentrations of the naturally occurring radionuclides in the salt samples from these mines were measured. Both active and passive techniques were employed for the measurement of radon with Radon Alpha Detector (RAD-7) and SSNTD respectively. The concentration of 222Rn was 26 ± 4 Bq m–3 measured by the active method while 43 ± 8 Bq m–3 was measured by the passive method. The activity concentration of the radionuclides was measured using gamma ray spectrometry with HPGe detector. The mean activity of 40K in salt samples was found to be 36 ± 20 Bq kg–1 and the concentration of 226Ra and 232Th in the salt samples was below the detection limits. Gamma radiation hazard was assessed in terms of the external gamma dose from salt slabs and the rooms made of salt and the annual effective dose due to gamma radiation. The exposure to radon daughters, annual effective dose and excessive lifetime cancer risk due to radon in the mines were estimated. The mean annual effective dose due to an intake of 40K from the salt was calculated as 20.0 ± 11.1 μSv, which is lower than the average annual effective dose rate of 0.29 mSv, received by the ingestion of natural radionuclides. Due to the low concentration values of primordial radionuclides in the salt and radon (222Rn) in the mines, a ‘low level activity measurement laboratory' is suggested to be established in these mines.

著者

三宅 泰雄 猿橋 勝子 葛城 幸雄 金沢 照子

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.2, no.1, pp.25-28, 1961-06-01 (Released:2006-08-29)

参考文献数

11

被引用文献数

14

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Concentration of Cs-137 and Sr-90 in the western North Pacific was determined. The content of Cs-137 ranged from 0.8 to 4.8 μμc/l while Sr-90 of 0.6 to 3.1 μμc/l was observed. These values are much higher than those obtained in the Atlantic and the eastern part of the North Pacific. The cause of higher contamination is due to the direct flowout of the fission product from the proving grounds in the tropical region of the Pacific. The reason for the lower ratio of Cs-137/Sr-90 in sea water is also discussed.

著者

Qiang LIU Bo JIANG Li-Ping JIANG Ying WU Xiao-Guang WANG Feng-Ling ZHAO Bao-Hua FU Turai ISTVAN Enhai JIANG

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.49, no.1, pp.63-69, 2008 (Released:2008-02-01)

参考文献数

12

被引用文献数

47

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On 26 April 1999, three persons were accidentally exposed by high dose 60Co irradiation. They suffered from severe (one case) or moderate (two cases) hemopoietic form of acute radiation sickness (ARS). As part of the comprehensive treatment, strict reverse isolation and granulocyte-macrophage colony-stimulating factor (GM-CSF) therapy were applied. All the patients recovered after an appropriate treatment for 83 days. In our experience, the correct diagnosis and effective treatment at an early stage proved to be helpful to the patients in pulling out from the critical stage of acute radiation sickness. To avoid menstruation by the female patient just in the critical stage, we modified her menstruation cycle by testosterone. In our view, GM-CSF should be given as early as possible with enough dosage for promoting early hematological reconstruction. The experience obtained from the medical management of these patients is valuable for the treatment of such patients in the future.

著者

佐伯 哲哉 町田 勇

出版者

日本放射線影響学会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.32, no.4, pp.366-377, 1991-12

被引用文献数

2

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After the photoaddition of mono- and bifunctional furocoumarins to G1 phase cells, most gene conversion and crossing-over occurred without post-irradiation incubation of these cells in incision-proficient strains. In contrast, incision-deficient cells showed marked induction of both recombinational events only after treated cells had been incubated for several hours before selection. These results indicate that when furocoumarins are photoadded to G1 cells, initiation of recombinational events occurs during the same G1 phase in the incision-proficient cells; whereas, it occurs only after post-irradiation DNA replication in incision-deficient cells. The action of the PSO2 gene product specific for the repair of DNA crosslinks in recombination induction is discussed and compared to the actions of the excision repair genes RAD1 and RAD2.

著者

神谷 研二 CLIFTON KELLY H. GOULD MICHAEL N. YOKORO KENJIRO

出版者

Journal of Radiation Research 編集委員会

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.32, no.2, pp.181-194, 1991

被引用文献数

2

---

We have developed an in vitro-in vivo transplantation assay for measuring the concentration of clonogenic epithelial cells in cell suspensions of rat mammary tissue. Rat mammary clonogens from organoid cultures are capable of the same degree of PLDR as clonogens in vivo. The growth and differentiation of mammary clonogens to alveolar colonies or ductal colonies is regulated as follows: a) in the presence of E<SUB>2</SUB> and high prolactin (Prl), cortisol induces mammary clonogens to proliferate and differentiate to form alveolar colonies which secrete milk and begin losing clonogenic potential, b) in cortisol deficient rats, Prl and E<SUB>2</SUB> synergistically stimulate non-secretory ductal colonies, formation of which retain clonogenic potential, c) E<SUB>2</SUB> without progesterone stimulates alveolar colony formation in the presence of cortisol and high Prl, d) progesterone inhibits mammary clonogen differentiation to milk-producing cells and induces ductogenesis in a dose responsive fashion in the presence of E<SUB>2</SUB>, cortisol and high Prl. High prolactin levels coupled with glucocorticoid deficiency increases the susceptibility to mammary carcinogenesis following low dose radiation exposure by increasing the number of total mammary clonogens which are the presumptive target cells and by stimulating their proliferation after exposure.

著者

Gen SUZUKI Ichiro YAMAGUCHI Hiromitsu OGATA Hideo SUGIYAMA Hidenori YONEHARA Fumiyoshi KASAGI Saeko FUJIWARA Yoshimi TATSUKAWA Ippei MORI Shinzo KIMURA

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.51, no.6, pp.683-689, 2010 (Released:2010-11-23)

参考文献数

23

被引用文献数

28

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In two previous nation-wide surveys in the late 1980s and early 1990s, Japanese indoor radon concentrations increased in homes built after the mid 1970s. In order to ascertain whether this trend continued, a nation-wide survey was conducted from 2007 to 2010. In total 3,900 houses were allocated to 47 prefectures by the Neyman allocation method and 3,461 radon measurements were performed (88.7% success). The fraction of reinforced concrete / concrete block buildings was 32.4%, similar to the value from national statistics. Arithmetic mean (standard deviation, SD) and geometric mean (geometric SD) of radon concentration after adjusting for seasonal fluctuation were 14.3 (14.7) and 10.8 (2.1) Bq/m3. The corresponding population-weighted values were 13.7 (12.3) and 10.4 (2.0) Bq/m3, respectively. It was estimated that only 0.1% of dwellings exceed 100 Bq/m3, a new WHO reference level for indoor radon. Radon concentrations were highest in houses constructed in the mid 1980s and decreased thereafter. In conclusion, arithmetic mean indoor radon in the present survey was slightly lower than in previous surveys and significant reductions in indoor radon concentrations in both wooden and concrete houses can be attributed to alterations in Japanese housing styles in recent decades.

著者

井上 義和 岩倉 哲男

出版者

Journal of Radiation Research Editorial Committee

雑誌

Journal of Radiation Research (ISSN:04493060)

巻号頁・発行日

vol.31, no.4, pp.311-323, 1990-12-15 (Released:2006-06-16)

参考文献数

15

被引用文献数

15

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Polished rice samples harvested in 1985 were collected from 25 prefectures throughout Japan. Concentrations of both tissue free water tritium (TFWT) and organically bound tritium (OBT) were determined. Nearly uniform distribution of the TFWT and OBT concentrations was observed in Japan, taking into account a relatively large counting error. The average values for all Japanese polished rice were 2.69 ±0.74 Bq/L for the TFWT concentration, 2.01 ±0.78 Bq/L for the OBT concentration and 0.83 ±0.32 for the specific activity ratio. The TFWT concentration was within the range of tritium concentration of the land water reported by other researchers. The specific activity ratio below unity also confirmed by analyses of the 4 Chinese polished rice samples suggests that OBT in the rice is not equilibrated with TFWT or HTO in the environment because of isotope discrimination.