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April 2006 - January 2008
Publications
Publications (87)
This study investigated the induction of DNA double-strand breaks (DSBs) in the hTERT-immortalized normal human diploid epithelial cells (RPE1-hTERT) continuously exposed to 6000 Bq/ml of tritiated water (HTO) and organically bound tritium (OBT). The relationship of the DSBs induction with the intracellular amount as well as the localization of tri...
Senescence-like growth arrest (SLGA), which is a radiation-induced cell death pathway, is induced in immortalized normal human epithelial cell (hTERT-RPE1) by the daily fractionated X-irradiation with 1.5 Gy within 30 times. We here demonstrate that pre-treatment induces acquired radioresistance (ARR) that can survive from the lethal fractionated r...
To quantitatively investigate the effects of chronic low-dose internal exposure to Cesium-137 on DNA damage, carcinogenicity, and offspring over multiple generations. The potential genetic risk in humans was predicted based on next-generation murine mutation rates to confirm the reasonableness of the current Cesium-137 dose limits for food. Cesium-...
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Importance of the evaluation of the physician’s eye exposure to radiation during ¹⁹⁸Au grain brachytherapy, given that the eye dose limit has been reduced drastically from 150 to 20 mSv/year.
Abstract
Brachytherapy is a practical, effective procedure for the local treatment of cancer; it delivers a high radiation dose to a lim...
We quantified the level of backscatter radiation generated from physicians’ heads using a phantom. We also evaluated the shielding rate of the protective eyewear and optimal placement of the eye-dedicated dosimeter (skin surface or behind the Pb-eyewear). We performed diagnostic X-rays of two head phantoms: Styrofoam (negligible backscatter radiati...
After the Fukushima nuclear power plant accident in 2011, many types of survey meters were used, including Geiger–Müller (GM) survey meters, which have long been used to measure β-rays. Recently, however, a novel radiation survey meter that uses a plastic-scintillation sensor has been developed. Although manufacturers’ catalog data are available fo...
Given the new recommendations for occupational eye lens doses, various lead glasses have been used to reduce irradiation of interventional radiologists. However, the protection afforded by lead glasses over prescription glasses (thus over-glasses-type eyewear) has not been considered in detail. We used a phantom to compare the protective effects of...
How does chronic low-dose internal exposure to Cesium-137 radiation over multiple generations affect offspring? In this study, we sought to infer the effects on humans from experiments on mice, whose spontaneous mutation rate in the next generation is very similar to that of humans. Cesium-137 water (100 Bq/mL) was provided as drinking water to A/J...
Although interventional radiology (IVR) is preferred over surgical procedures because it is less invasive, it results in increased radiation exposure due to long fluoroscopy times and the need for frequent imaging. Nurses engaged in cardiac IVR receive the highest lens radiation doses among medical workers, after physicians. Hence, it is important...
The signal intensities of CO2− radicals in teeth can be utilised as an individual indicator of the cumulative external dose for animals. To accurately determine the external dose, it is desirable to analyse the CO2− radical intensity and improve its detection limit. We recently reported a dose–response in the range of 0–200 mGy and estimated the ab...
The International Commission on Radiological Protection has lowered the annual equivalent eye-lens dose to 20 mSv. Although occupational exposure can be high in nuclear medicine (NM) departments, few studies have been conducted regarding eye-lens exposure among NM staff. This study aimed to estimate the annual lens doses of staff in an NM departmen...
The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (aka Nihonzaru or snow monkey) due to the Fukushima nuclear power plant accident. Images of a male Japanese macaque weighing ~10 kg were acquired using a multi-slice computed tomography (CT) scan with a 64-row segment detector. The CT images were used to c...
Mobile radiography allows for the diagnostic imaging of patients who cannot move to the X-ray examination room. Therefore, mobile X-ray equipment is useful for patients who have difficulty with movement. However, staff are exposed to scattered radiation from the patient, and they can receive potentially harmful radiation doses during radiography. W...
In 2011, the International Commission on Radiological Protection (ICRP) recommended a significant reduction in the lens-equivalent radiation dose limit, thus from an average of 150 to 20 mSv/year over 5 years. In recent years, the occupational dose has been rising with the increased sophistication of interventional radiology (IVR); management of IV...
Radiation protection/evaluation during interventional radiology (IVR) poses a very important problem. Although IVR physicians should wear protective aprons, the IVR physician may not tolerate wearing one for long procedures because protective aprons are generally heavy. In fact, orthopedic problems are increasingly reported in IVR physicians due to...
Since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, we have established an archive system of livestock and wild animals from the surrounding ex‐evacuation zone. Wildlife within the alert zone have been exposed to low‐dose‐rate (LDR) radiation for a long continuous time. In this study, we analysed the morphological characteristics of t...
In recent years, endovascular treatment of aortic aneurysms has attracted considerable attention as a promising alternative to traditional surgery. Hybrid operating room systems (HORSs) are increasingly being used to perform endovascular procedures. The clinical benefits of endovascular treatments using HORSs are very clear, and these procedures ar...
The aim of this study was to determine parameters for estimating the internal exposure of all organs in mouse experiments from the radioactivity concentration in organs. The estimation of internal exposure rate conversion coefficients and absorbed fractions for 137Cs, 134Cs and 90Sr by the Particle and Heavy Ion Transport code System (PHITS) with a...
The relationship between the CO2 radical intensity and the absorbed dose (dose response curve) of tooth enamel of Japanese macaque was observed by electron spin resonance and the detection limit of our system was estimated to be 33.5 mGy. Using the dose response curve, external exposure dose for seven wild Japanese macaques captured in Fukushima pr...
In order to understand the effect of chronic exposure to low-dose-rate radiation on female fertilities and the risk of heritable genetic effects on domestic animals after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident, we assessed the developmental ability of oocytes, and examined the histological characters and structure of ovaries. We...
Insoluble radioactive particles have been found in the terrestrial, aquatic and aerial environments. Hot particles are well known as insoluble radioactive particles found after the nuclear tests and the accident at Chernobyl Nuclear Power Plant (CNPP). Hot particles are highly radioactive pieces and mainly composed of nuclear fuel. Insoluble radioa...
Cumulative dose of external and internal exposures following the Fukushima Daiichi Nuclear Power Plant (FNPP) accident was estimated for Japanese macaques (Macaca fuscata) around FNPP. Conversion factors for Japanese macaques modeled as ellipsoids were estimated for external exposure from contaminated ground and internal exposure uniformly distribu...
The Fukushima nuclear power plant (FNPP) accident raised worldwide attention to the health risk of radiation exposure and to its potential transgenerational effects. Here, we analysed transgenerational effects on calf spermatogenesis and on blood plasma metabolome in order to detect alterations associated with paternal exposure to low-dose-rate (LD...
To monitor radiocesium activity in skeletal muscle of live cattle, the animals were given radiocesium-contaminated feed continuously, then switched to contamination-free feed after radiocecium concentration in peripheral blood (PB) reached plateau. Radioactivity in skeletal muscles of neck and rump was measured by attaching the probe of a NaI surve...
Abstract Several populations of wild Japanese macaques (Macaca fuscata) inhabit the area around Fukushima Daiichi Nuclear Power Plant (FNPP). To measure and control the size of these populations, macaques are captured annually. Between May 2013 and December 2014, we performed a haematological analysis of Japanese macaques captured within a 40-km ra...
The Fukushima Daiichi Nuclear Power Plant (FNPP) accident, the largest nuclear incident since the 1986 Chernobyl disaster, occurred when the plant was hit by a tsunami triggered by the Great East Japan Earthquake on March 11, 2011. The subsequent uncontrolled release of radioactive substances resulted in massive evacuations in a 20-km zone. To bett...
Chromosome rearrangement is clinically and physiologically important because it can produce oncogenic fusion genes. Chromosome rearrangement requires DNA double-strand breaks (DSBs) at two genomic locations and misrejoining between the DSBs. Before DSB misrejoining, two DSB-containing chromatin regions move and pair with each other; however, the mo...
In this study we analyzed the effect of chronic and low-dose-rate (LDR) radiation on spermatogenic cells of large Japanese field mice ( Apodemus speciosus ) after the Fukushima Daiichi Nuclear Power Plant (FNPP) accident. In March 2014, large Japanese field mice were collected from two sites located in, and one site adjacent to, the FNPP ex-evacuat...
The effect of the Fukushima Daiichi Nuclear Power Plant (FNPP) accident on humans and the environment is a global concern. We performed biochemical analyses of plasma from 49 Japanese Black cattle that were euthanized in the ex-evacuation zone set within a 20-km radius of FNPP. Among radionuclides attributable to the FNPP accident, germanium gamma-...
Correlation analysis between dose rate and cumulative dose of the individual cattle in the ex-evacuation zone.
r and p is Pearson’s correlation coefficient and p values, respectively.
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Representative gamma-spectrometry profile of the skeletal muscle and soil.
134Cs and 137Cs were vast majority of radionuclides in both skeletal muscle of cattle and soil because 5 months or more had passed since the FNPP accident. Sampling of the skeletal muscle and the soil was performed on January 2012 and July 2012 at the same place in the ex-ev...
Correlation analysis between cumulative dose from radiocesium and plasma component levels in cattle of the ex-evacuation zone.
r is Pearson’s correlation coefficient. p values are Shown in S4 Table.
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137Cs concentrations in the peripheral blood and the skeletal muscle of cattle in the ex-evacuation zone.
The dot plot shows the correlation of the 137Cs concentration of peripheral blood with that of the skeletal muscle in cattle in the ex-evacuation zone. r indicates coefficient of determination. p value is below 0.001.
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Correlation coefficient between dose rate and plasma components in cattle of the ex-evacuation zone.
r and p is Pearson’s correlation coefficient and p value, respectively.
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Radiocesium concentrations in the skeletal muscle of individual cattle and that in the soil where cattle were captured.
Numbers in red indicate the values calculated from radiocesium concentration of blood.
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Correlation coefficient between oxidative stress markers and other plasma components in cattle of the ex-evacuation zone.
r and p is indicate Pearson’s correlation coefficient and p values, respectively.
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Histological findings observed in each tissue.
a-e. H&E staining. f. Iron staining by Prussian blue staining. a, b. Sarcocystis cysts in the H1 biceps femoris muscle. c. inflammatory cell infiltration in the L6 liver. d. inflammatory cell infiltration of kidney in the L2 kidney. e, f. Hemosiderin deposition in the L5 Spleen.
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Cumulative dose of internal and external exposure of radiocesium.
Cumulative dose from 134Cs and 137Cs during certain duration were calculated as a calculation formula written on this Table.
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Correlation coefficient between cumulative dose and plasma components in cattle of the ex-evacuation zone.
r and p is Pearson’s correlation coefficient and p values, respectively.
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Histological findings in 12 cattle of the ex-evacuation zone.
S, Sarcocystis cyst; N, no abnormalities; -, no histological analysis; H, Hemosiderin deposition; I, Inflammatory cell infiltration.
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It is not an exaggeration to say that, without nuclear accidents or the analysis of radiation therapy, there is no way in
which we are able to quantify radiation effects on humans. Therefore, the livestock abandoned in the ex-evacuation zone and
euthanized due to the Fukushima Daiichi Nuclear Power Plant (FNPP) accident are extremely valuable for a...
We aimed to investigate the effect of chronic radiation exposure associated with the Fukushima Daiichi Nuclear Power Plant
(FNPP) accident on the testes of boar and inobuta (a hybrid of Sus scrofa and Sus scrofa domestica). This study examined the contamination levels of radioactive caesium (Cs), especially 134Cs and 137Cs, in the testis of both bo...
Standard fractionated radiotherapy for the treatment of cancer consists of daily irradiation of 2-Gy X-rays, 5 days a week for 5 to 8 weeks. To understand the characteristics of radioresistant cancer cells and to develop more effective radiotherapy, we established a series of novel, clinically relevant radioresistant (CRR) cells, which continue to...
Downstream factors that regulate the decision between senescence and cell death have not been elucidated. Cells undergo senescence through three pathways, replicative senescence (RS), stress-induced premature senescence (SIPS) and oncogene-induced senescence. Recent studies suggest that the ataxia telangiectasia mutant (ATM) kinase is not only a ke...
We aimed to investigate the effect of chronic radiation exposure associated with the Fukushima Daiichi Nuclear Plant accident on the testis from 2 bulls. Estimated dose of internal exposure in one bull was 0.7-1.2 mGy ((134)Cs) and 0.4-0.6 mGy ((137)Cs) and external exposure was 2.0 mGy ((134)Cs) and 0.8 mGy ((137)Cs) (196 days). Internal dose in t...
Foci of phosphorylated histone H2AX and ATM are the surrogate markers of DNA double strand breaks. We previously reported that the residual foci increased their size after irradiation, which amplifies DNA damage signals. Here, we addressed whether amplification of DNA damage signal is involved in replicative senescence of normal human diploid fibro...
Neural stem cells (NSCs) are highly susceptible to DNA double-strand breaks; however, little is known about the effects of radiation in cells surviving radiation. Although the nestin-positive NSCs predominantly became glial fibrillary acidic protein (GFAP)-positive in differentiation-permissive medium, little or no cells were GFAP positive in proli...
Senescence-like growth arrest in human solid carcinomas is now recognized as the major outcome of radiotherapy. This study was designed to analyze cell cycle during the process of senescence-like growth arrest in mammary carcinoma cells exposed to X-rays.
Fluorescent ubiquitination-based cell cycle indicators were introduced into the human mammary...
It is well documented that deficiency in ataxia telangiectasia mutated (ATM) protein leads to elevated frequency of chromosome translocation, however, it remains poorly understood how ATM suppresses translocation frequency. In the present study, we addressed the mechanism of ATM-dependent suppression of translocation frequency. To know frequency of...
Cell cycle checkpoints are essential cellular process protecting the integrity of the genome from DNA damaging agents. In the present study, we developed a microcolony assay, in which normal human diploid fibroblast-like cells exposed to ionizing radiation, were plated onto coverslips at very low density (3 cells/cm(2)). Cells were grown for up to...
Asymmetric division of the SAGM-grown cells. A, Scheme of cell divisions. Representative data obtained by time-lapse imaging of cell cycle are shown. ACD: asymmetric cell division, SCD: symmetric cell division. 6.1% of the cells showed asymmetric division after first division. Total 198 cells were analyzed. B, Representative images after asymmetric...
Time-course expression of lineage-specific markers.
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Colony formation in SAGM after FACS.
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While identification and isolation of adult stem cells have potentially important implications, recent reports regarding dedifferentiation/reprogramming from differentiated cells have provided another clue to gain insight into source of tissue stem/progenitor cells. In this study, we developed a novel culture system to obtain dedifferentiated proge...
We describe a protocol for creating localized DNA double-strand breaks (DSBs) with minimal requirements that can be applied in cell biology and molecular biology. This protocol is based on the combination of 5-bromo-2'-deoxyuridine (BrdU) labeling and ultraviolet C (UVC) irradiation through porous membranes. Cells are labeled with 10 μM BrdU for 48...
DNA double strand breaks induced by DNA damaging agents, such ionizing radiation, are repaired by multiple DNA repair pathways including non-homologous end-joining (NHEJ) repair and homologous recombination (HR) repair. ATM-dependent DNA damage checkpoint regulates a part of DNA repair pathways, however, the exact role of ATM activity remains to be...
Colocalization of the foci of phosphorylated proteins. Synchronized normal human diploid cells in G1 were electroporated with Pvu II (100 U) as described in METHODS. The cells were incubated for 12 hours before fixation.
An ataxia-telangiectasia mutated (ATM)-dependent DNA damage signal is amplified through the interaction of various factors, which are recruited to the chromatin regions with DNA double-strand breaks. Spatial and temporal regulation of such factors is analysed by fluorescence microscopy in combination with laser micro-irradiation. Here we describe a...
Secretory clusterin (sCLU) is a pro-survival factor that can be induced by cellular stress, including ionizing radiation (IR),
many cytotoxic agents, and during cellular replicative or low doses of stress-induced senescence. sCLU expression changes
with tumor stage and grade in various types of cancer. Previously our laboratory found that sCLU was...
Replicative senescence is a fundamental feature in normal human diploid cells and results from dysfunctional telomeres at the Hayflick cell division limit. Ionizing radiation (IR) prematurely induces the same phenotypes as replicative senescence prior to the Hayflick limit. This process is known as stress-induced premature senescence (SIPS). Since...
Replicative senescence is a fundamental feature in normal human diploid cells and results from dysfunctional telomeres at the Hayflick cell division limit. Ionizing radiation (IR) prematurely induces the same phenotypes as replicative senescence prior to the Hayflick limit. This process is known as stress-induced premature senescence (SIPS). Since...
The microenvironment is consisted both of soluble factors involving growth factors and of insoluble factors. Stroma cells contribute to form the microenvironment through a secretion of these factors. Fibroblast, which is known as stroma cells, also secretes various soluble/ insoluble factors, but the secretion level is significantly up-regulated wh...
As the molecular processes in signal transduction during cell stress and senescence (aging), and cancer progression are elucidated, it is clear that certain elements are common amongst these cellular events. Our working hypothesis is that specific cell stress processes activated during the stress of cellular replicative senescence become permanentl...
Histone H2AX is phosphorylated and forms foci in response to exposure to ionizing radiation. It has been thought that phosphorylated histone H2AX foci reflect unrepaired DNA double-strand breaks; however, we report here the localization of phosphorylated histone H2AX foci at the site of rejoined DNA double-strand breaks. We observed that phosphoryl...
Various stresses including ionizing radiation give normal human fibroblasts a phenotype of senescence-like growth arrest (SLGA), manifested by p53-dependent irreversible G1 arrest. To determine the mechanism of persistent activation of p53, we examined phosphorylated Ataxia telangiectasia mutated (ATM) and phosphorylated histone H2AX foci formation...
We examined the delayed induction of telomere instability in hTERT-immortalized normal human fibroblast (BJ1-hTERT) cells exposed to X-rays. BJ1-hTERT cells were irradiated with 2 Gy of X-rays, and chromosome aberrations were analyzed 24 hours after irradiation and in the surviving cells 14 days after X-ray exposure. We found that the X-ray-survivi...
The p53 protein is accumulated and activated as a transcription factor in response to various types of stress. Posttranslational modification, such as phosphorylation and acetylation, are involved in this process. After X-irradiation, for example, the p53 protein at Ser15 is phosphorylated by the ATM kinase, which recognizes DNA double-strand break...
