Yuko Kinashi

Kyoto University, Kioto, Kyoto, Japan

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Publications (149)307.75 Total impact

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    ABSTRACT: Boron neutron capture therapy (BNCT) is a particle radiation therapy that involves the use of a thermal or epithermal neutron beam in combination with a boron (10B)-containing compound that specifically accumulates in tumor. 10B captures neutrons and the resultant fission reaction produces an alpha (4He) particle and a recoiled lithium nucleus (7Li). These particles have the characteristics of high linear energy transfer (LET) radiation and therefore have marked biological effects. High-LET radiation is a potent inducer of DNA damage, specifically of DNA double-strand breaks (DSBs). The aim of the present study was to clarify the role of DNA ligase IV, a key player in the non-homologous end-joining repair pathway, in the repair of BNCT-induced DSBs. We analyzed the cellular sensitivity of the mouse embryonic fibroblast cell lines Lig4−/− p53−/− and Lig4+/+ p53−/− to irradiation using a thermal neutron beam in the presence or absence of 10B-para-boronophenylalanine (BPA). The Lig4−/− p53−/− cell line had a higher sensitivity than the Lig4+/+ p53−/−cell line to irradiation with the beam alone or the beam in combination with BPA. In BNCT (with BPA), both cell lines exhibited a reduction of the 50 % survival dose (D 50) by a factor of 1.4 compared with gamma-ray and neutron mixed beam (without BPA). Although it was found that 10B uptake was higher in the Lig4+/+ p53−/− than in the Lig4−/− p53−/− cell line, the latter showed higher sensitivity than the former, even when compared at an equivalent 10B concentration. These results indicate that BNCT-induced DNA damage is partially repaired using DNA ligase IV.
    No preview · Article · Nov 2015 · Biophysik
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    ABSTRACT: Purpose: Research and development of various accelerator-based irradiation systems for boron neutron capture therapy (BNCT) is underway throughout the world. Many of these systems are nearing or have started clinical trials. Before the start of treatment with BNCT, the relative biological effectiveness (RBE) for the fast neutrons (over 10 keV) incident to the irradiation field must be estimated. Measurements of RBE are typically performed by biological experiments with a phantom. Although the dose deposition due to secondary gamma rays is dominant, the relative contributions of thermal neutrons (below 0.5 eV) and fast neutrons are virtually equivalent under typical irradiation conditions in a water and/or acrylic phantom. Uniform contributions to the dose deposited from thermal and fast neutrons are based in part on relatively inaccurate dose information for fast neutrons. This study sought to improve the accuracy in the dose estimation for fast neutrons by using two phantoms made of different materials in which the dose components can be separated according to differences in the interaction cross sections. The development of a “dual phantom technique” for measuring the fast neutron component of dose is reported.
    No preview · Article · Nov 2015 · Medical Physics
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    ABSTRACT: It is important that improvements are made to depth dose distribution in boron neutron capture therapy, because the neutrons do not reach the innermost regions of the human body. Here, we evaluated the dose distribution obtained using multiple-field irradiation in simulation. From a dose volume histogram analysis, it was found that the mean and minimum tumor doses were increased using two-field irradiation, because of improved dose distribution for deeper-sited tumors. Copyright © 2015. Published by Elsevier Ltd.
    No preview · Article · Jul 2015 · Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine
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    ABSTRACT: At the Kyoto University Research Reactor Institute (KURRI), a clinical study of boron neutron capture therapy (BNCT) using a neutron irradiation facility installed at the research nuclear reactor has been regularly performed since February 1990. As of November 2014, 510 clinical irradiations were carried out using the reactor-based system. The world’s first accelerator-based neutron irradiation system for BNCT clinical irradiation was completed at this institute in early 2009, and the clinical trial using this system was started in 2012. A shift of BCNT from special particle therapy to a general one is now in progress. To promote and support this shift, improvements to the irradiation system, as well as its preparation, and improvements in the physical engineering and the medical physics processes, such as dosimetry systems and quality assurance programs, must be considered. The recent advances in BNCT at KURRI are reported here with a focus on physical engineering and medical physics topics.
    No preview · Article · Jul 2015 · Journal- Korean Physical Society
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    ABSTRACT: An important application of neutron beam is boron neutron capture therapy(BNCT). Many facilities have recently been planning to use an accelerator for BNCT, in which cancer cells as well as normal cells near a cancerous region may be exposed to neutron beams with different energy profiles. In the present study, the cell killing effect and induction of DNA double-strand breaks(DNA-dsb) by neutron beams of different energy profiles were studied in Chinese hamster ovary(CHO-K1) cells and their radiosensitive mutant(xrs-5) cells. A neutron beam with mean energy 2MeV generated by the Neutron Exposure Accelerator System for Biological Effect Experiments(NASBEE) was more effective for cell killing than the thermal to epithermal neutron beams generated by the Heavy Water Facility of the Kyoto University Research Reactor(KUR-HWF). A focus assay of the repair protein of 53BP1 revealed a significant induction of DNA-dsb by these two neutron beams, but no significant difference in the induction and repair capabilities was noted between the two. These data suggest that an increase in the mean energy of neutron beam from thermal to fast neutrons increases cell killing effects, but not the induction of DNA-dsb.
    No preview · Article · Jan 2015 · Radioisotopes
  • Keiko Seki · Yuko Kinashi · Sentaro Takahashi
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    ABSTRACT: The tumor suppressor gene p53 is mutated in glioblastoma. We studied the relationship between the p53 gene and the biological effects of boron neutron capture therapy (BNCT). The human glioblastoma cells; A172, expressing wild-type p53, and T98G, with mutant p53, were irradiated by the Kyoto University Research Reactor (KUR). The biological effects after neutron irradiation were evaluated by the cell killing effect, 53BP1 foci assay and apoptosis induction. The survival-fraction data revealed that A172 was more radiosensitive than T98G, but the difference was reduced when boronophenylalanine (BPA) was present. Both cell lines exhibited similar numbers of foci, suggesting that the initial levels of DNA damage did not depend on p53 function. Detection of apoptosis revealed a lower rate of apoptosis in the T98G. BNCT causes cell death in glioblastoma cells, regardless of p53 mutation status. In T98G cells, cell killing and apoptosis occurred effectively following BNCT. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.
    No preview · Article · Jan 2015 · Anticancer research
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    ABSTRACT: Aim: In this study, we investigated γH2AX foci as markers of DSBs in normal brain and brain tumor tissue in mouse after BNCT. Background: Boron neutron capture therapy (BNCT) is a particle radiation therapy in combination of thermal neutron irradiation and boron compound that specifically accumulates in the tumor. 10B captures neutrons and produces an alpha (4He) particle and a recoiled lithium nucleus (7Li). These particles have the characteristics of extremely high linear energy transfer (LET) radiation and therefore have marked biological effects. High LET radiation causes severe DNA damage, DNA DSBs. As the high LET radiation induces complex DNA double strand breaks (DSBs), large proportions of DSBs are considered to remain unrepaired in comparison with exposure to sparsely ionizing radiation. Materials and methods: We analyzed the number of γH2AX foci by immunohistochemistry 30. min or 24. h after neutron irradiation. Results: In both normal brain and brain tumor, γH2AX foci induced by 10B(n,α)7Li reaction remained 24h after neutron beam irradiation. In contrast, γH2AX foci produced by γ-ray irradiation at contaminated dose in BNCT disappeared 24h after irradiation in these tissues. Conclusion: DSBs produced by 10B(n,α)7Li reaction are supposed to be too complex to repair for cells in normal brain and brain tumor tissue within 24h. These DSBs would be more difficult to repair than those by γ-ray. Excellent anti-tumor effect of BNCT may result from these unrepaired DSBs induced by 10B(n,α)7Li reaction.
    Full-text · Article · Oct 2014 · Reports of Practical Oncology and Radiotherapy
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    ABSTRACT: Background: Conventional therapies for diseases that are associated with protein aggregation typically prevent rather than clear protein aggregates. We have proposed neutron dynamic therapy (NDT) as a physical clearance therapy for protein aggregates. Advanced glycation end-products (AGEs), which are aggregated proteins, have been implicated in diabetes, Alzheimer's, and heart disease. Herein, we report the use of the boron tracedrug UTX-51, under thermal neutron irradiation, as an NDT for the targeted clearance of glycated bovine serum albumin (Gly-BSA), a model of AGEs. Materials and methods: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was performed to detect Gly-BSA decomposition by thermal neutron irradiation treated with UTX-51. Results: The combination of UTX-51 with neutron irradiation showed a decrease in band intensity of Gly-BSA. Conclusion: We present our NDT strategy, which has been used for the targeted clearance of Gly-BSA, suggesting that NDT with boron tracedrugs can be used for the treatment of AGEs-related disease.
    No preview · Article · Aug 2014 · Anticancer research
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    ABSTRACT: Radiation doses during boron neutron capture therapy for body-trunk tumors were estimated for various internal organs, using data from patients treated at Kyoto University Research Reactor Institute. Dose-volume histograms were constructed for tissues of the lung, liver, kidney, pancreas, and bowel. For pleural mesothelioma, the target total dose to the normal lung tissues on the diseased side is 5 Gy-Eq in average for the whole lung. It was confirmed that the dose to the liver should be carefully considered in cases of right lung disease.
    No preview · Article · Jun 2014 · Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine
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    ABSTRACT: It is important to measure the microdistribution of 10B in a cell to predict the cell-killing effect of new boron compounds in the field of boron neutron capture therapy. Alpha autoradiography has generally been used to detect the microdistribution of 10B in a cell. Although it has been performed using a reactor-based neutron source, the realization of an accelerator-based thermal neutron irradiation field is anticipated because of its easy installation at any location and stable operation. Therefore, we propose a method using a cyclotron-based epithermal neutron source in combination with a water phantom to produce a thermal neutron irradiation field for alpha autoradiography. This system can supply a uniform thermal neutron field with an intensity of 1.7×109 (cm−2 s−1) and an area of 40 mm in diameter. In this presentation, we give an overview of our proposed system and describe a demonstration test using a mouse liver sample injected with 500 mg/kg of boronophenyl-alanine.
    No preview · Article · Jun 2014 · Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine
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    ABSTRACT: We report the radiation doses encountered by 59 Kyoto University Research Reactor Institute (KURRI) staff members who had been dispatched to screen refugees for radiation at emergency evacuation sites 45–80 km from the Tokyo Electric Power Co. (TEPCO) Fukushima Daiichi Nuclear Power Plant. From March 20 to April 30, 2011, 42 members were dispatched to the emergency evacuation sites located 45–80 km from the power plant to examine the radioactive contamination affecting refugees. Continuously, from May 10 to May 23, 2011, 17 members were dispatched to Fukushima Prefecture to establish the Kyoto University Radiation Mapping (KURAMA) system. Body burdens of radioactive nuclides were estimated using a whole-body counter. The first team dispatched showed 1,300–1,929 Bq internal radiation activity from cesium (including 137Cs and 134Cs) and 48–118 Bq 131I. The internal doses of four members of the first team were estimated to be 24–39 μSv. The doses from internal exposure were almost similar to the cumulative external doses for the dispatch period (March 20–22, 2011) The external radiation doses of members dispatched after the second team had decreased from one third to less than one tenth of the external doses of the first dispatched team. The internal radiation doses of 55 members after the second team showed that 51 cases were undetectable and 4 cases showed doses of 2–15 μSv.
    No preview · Chapter · Jan 2014
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    ABSTRACT: It is generally said that low LET radiation produce high dose-rate effect, on the other hand, no significant dose rate effect is observed in high LET radiation. Although high LET radiations are produced in BNCT, little is known about dose-rate effect of BNCT. T98G cells, which were tumor cells, were irradiated by neutron mixed beam with BPA. As normal tissue derived cells, Chinese hamster ovary (CHO-K1) cells and DNA double strand breaks (DNA-DSBs) repair deficient cells, xrs5 cells were irradiated by the neutrons (not including BPA). To DNA-DSBs analysis, T98G cells were stained immunochemically with 53BP1 antibody. The number of DNA-DSBs was determined by counting 53BP1 foci. There was no dose-rate effect in xrs5 cells. D0 difference between 4cGy/min and 20cGy/min irradiation were 0.5 and 5.9 at the neutron and gamma-ray irradiation for CHO-K1, and 0.3 at the neutron for T98G cells. D0 difference between 20cGy/min and 80cGy/min irradiation for T98G cells were 1.2 and 0.6 at neutron irradiation plus BPA and gamma-ray. The differences between neutron irradiations at the dose rate in T98G cells were supported by not only the cell viability but also 53BP1 foci assay at 24h following irradiation to monitor DNA-DSBs. Dose-rate effect of BNCT when T98G cells include 20ppm BPA was greater than that of gamma-ray irradiation. Moreover, Dose-rate effect of the neutron beam when CHO-K1 cells did not include BPA was less than that of gamma-ray irradiation These present results may suggest the importance of dose-rate effect for more efficient BNCT and the side effect reduction.
    No preview · Article · Dec 2013 · Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine
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    ABSTRACT: We retrospectively review outcomes of applying boron neutron capture therapy (BNCT) to unresectable advanced or recurrent head and neck cancers. Patients who were treated with BNCT for either local recurrent or newly diagnosed unresectable head or neck cancers between December 2001 and September 2007 were included. Clinicopathological characteristics and clinical outcomes were retrieved from hospital records. Either a combination of borocaptate sodium and boronophenylalanine (BPA) or BPA alone were used as boron compounds. In all the treatment cases, the dose constraint was set to deliver a dose <10-12 Gy-eq to the skin or oral mucosa. There was a patient cohort of 62, with a median follow-up of 18.7 months (range, 0.7-40.8). A total of 87 BNCT procedures were performed. The overall response rate was 58% within 6 months after BNCT. The median survival time was 10.1 months from the time of BNCT. The 1- and 2-year overall survival (OS) rates were 43.1% and 24.2%, respectively. The major acute Grade 3 or 4 toxicities were hyperamylasemia (38.6%), fatigue (6.5%), mucositis/stomatitis (9.7%) and pain (9.7%), all of which were manageable. Three patients died of treatment-related toxicity. Three patients experienced carotid artery hemorrhage, two of whom had coexistent infection of the carotid artery. This study confirmed the feasibility of our dose-estimation method and that controlled trials are warranted.
    Full-text · Article · Aug 2013 · Journal of Radiation Research
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    ABSTRACT: Since 1990, Boron Neutron Capture Therapy (BNCT) has been used for over 400 cancer patients at the Kyoto University Research Reactor Institute (KURRI). After BNCT, the patients are radioactive and their 24Na and 38Cl levels can be detected via a Na-I scintillation counter. This activity is predominantly due to 24Na, which has a half-life of 14.96 h and thus remains in the body for extended time periods. Radioactive 24Na is mainly generated from 23Na in the target tissue that is exposed to the neutron beam in BNCT. The purpose of this study is to evaluate the relationship between the radioactivity of blood 24Na following BNCT and the absorbed gamma ray dose in the irradiated field. To assess blood 24Na, 1 ml of peripheral blood was collected from 30 patients immediately after the exposure, and the radioactivity of blood 24Na was determined using a germanium counter. The activity of 24Na in the blood correlated with the absorbed gamma ray doses in the irradiated field. For the same absorbed gamma ray dose in the irradiated field, the activity of blood 24Na was higher in patients with neck or lung tumors than in patients with brain or skin tumors. The reasons for these findings are not readily apparent, but the difference in the blood volume and the ratio of bone to soft tissue in the irradiated field, as well as the dose that leaked through the clinical collimator, may be responsible.
    Full-text · Article · Feb 2013 · Journal of Radiation Research
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    ABSTRACT: Boron neutron capture therapy is one of the radiation therapy using high intensity neutron up to 109 (cm− 2 s− 1). To evaluate prescript dose, it is important to separately detect thermal neutron flux and gamma dose. In our institute, Thermo-Luminescence Dosimeter (TLD) with the low sensitivity for thermal neutron to detect gamma ray dose, gold foil to detect thermal neutron flux have been used. TLD for detecting gamma ray dose at mixed field of intense neutrons can not be available because of discontinued products. Furthermore, we have successfully established the accelerator based neutron source for BNCT, it is desirable to develop new dosimeter instead of TLD. We propose the method using Glass Rod Dosimeter (GRD) with thermal neutron shielding. In order to evaluate thermal neutron fluence, the combination with GRD and boron nitride as a thermal neutron converter was also developed. Overview of new detection method and the results of performance test report in this paper.
    No preview · Chapter · Jan 2013
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    ABSTRACT: Reirradiation is rarely applied to locally recurrent tumor in the previously irradiated region due to the expectation of severe side effects. Boron neutron capture therapy (BNCT) can deposit a large dose with a steep gradient between the tumor and surrounding normal tissues. We treated a patient with recurrent lung cancer in the previously irradiated chest wall with two-fractionated BNCT. In this case, most of the tumor regressed at seven months after the BNCT. No acute or late adverse events were observed. Locally re-recurrent tumor was found at the margin of the radiation field due to the inhomogeneous distribution of the neutron beam in the beam field. Although two-fractionated BNCT may be feasible for the treatment of locally recurrent shallow-seated tumors, especially from the view of palliation, attempts to improve the dose distribution should be considered.
    No preview · Article · Oct 2012
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    ABSTRACT: Understanding the biological effects of neutron mixed-beam irradiation used for boron neutron capture therapy (BNCT) is important in order to improve the efficacy of the therapy and to reduce side effects. In the present study, cell viability and DNA double-strand breaks (DNA-DSBs) were examined in Chinese hamster ovary cells (CHO-K1) and their radiosensitive mutant cells (xrs5, Ku80-deficient), following neutron mixed-beam irradiation for BNCT. Cell viability was significantly impaired in the neutron irradiation groups compared to the reference gamma-ray irradiation group. The relative biological effectiveness for 10% cell survival was 3.3 and 1.2 for CHO-K1 and xrs5 cells, respectively. There were a similar number of 53BP1 foci, indicators of DNA-DSBs, in the neutron mixed-beam and the gamma-ray groups. In addition, the size of the foci did not differ between groups. However, neutron mixed-beam irradiation resulted in foci with different spatial distributions. The foci were more proximal to each other in the neutron mixed-beam groups than the gamma-ray irradiation groups. These findings suggest that neutron beams may induce another type of DNA damage, such as clustered DNA-DSBs, as has been indicated for other high-LET irradiation.
    Full-text · Article · Sep 2012 · Journal of Radiation Research
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    ABSTRACT: To evaluate the effects of employing a (10)B-carrier and manipulating intratumour hypoxia on local tumour response and lung metastatic potential in boron neutron capture therapy (BNCT) by measuring the response of intratumour quiescent (Q) cells. B16-BL6 melanoma tumour-bearing C57BL/6 mice were continuously given 5-bromo-2'-deoxyuridine (BrdU) to label all proliferating (P) cells. The tumours received reactor thermal neutron beam irradiation following the administration of a (10)B-carrier [L-para-boronophenylalanine-(10)B (BPA) or sodium mercaptoundecahydrododecaborate-(10)B (BSH)] in combination with an acute hypoxia-releasing agent (nicotinamide) or mild temperature hyperthermia (MTH). Immediately after the irradiation, cells from some tumours were isolated and incubated with a cytokinesis blocker. The responses of the Q and total (P+Q) cell populations were assessed based on the frequency of micronuclei using immunofluorescence staining for BrdU. In other tumour-bearing mice, macroscopic lung metastases were enumerated 17 days after irradiation. BPA-BNCT increased the sensitivity of the total tumour cell population more than BSH-BNCT. However, the sensitivity of Q cells treated with BPA was lower than that of BSH-treated Q cells. With or without a (10)B-carrier, MTH enhanced the sensitivity of the Q cell population. Without irradiation, nicotinamide treatment decreased the number of lung metastases. With irradiation, BPA-BNCT, especially in combination with nicotinamide treatment, showed the potential to reduce the number of metastases more than BSH-BNCT. BSH-BNCT in combination with MTH improves local tumour control, while BPA-BNCT in combination with nicotinamide may reduce the number of lung metastases.
    Full-text · Article · Mar 2012 · The British journal of radiology
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    ABSTRACT: At Kyoto University Research Reactor Institute, clinical studies of around 400 of Boron Neutron Capture Therapy (BNCT) have been performed using research reactor. On the other hand, we have developed cyclotron based epithermal neutron source. To improve the quality of treatment, it is necessary to perform the detection of two dimensional thermal neutron distribution before and during treatment as quality control. Generally, the method of activation using gold foiVwire and germanium semiconductor detector is applied to detection of thermal neutron flux at several positions. However, the activation method using semiconductor detector takes some time to decide the thermal neutron flux. Therefore, we propose the method using multi-wire proportional counter for detection of two dimensional thermal neutron distribution. We constructed the system consisting of multi-wire detection head, multi-channel preamplifier, multi-channel discriminator, centroid calculation circuit, and data acquisition system. Detection efficiency for BNCT irradiation field was evaluated using Am-Be neutron source with moderator for producing thermal neutrons. Furthermore, two dimensional thermal neutron distribution was demonstrably obtained.
    No preview · Conference Paper · Jan 2012

  • No preview · Article · Jan 2012 · Radioisotopes

Publication Stats

1k Citations
307.75 Total Impact Points


  • 1990-2015
    • Kyoto University
      • Research Reactor Institute
      Kioto, Kyoto, Japan
  • 2006-2009
    • The University of Tokushima
      • • Department of Biological Science and Technology
      • • Faculty of Engineering
      Tokusima, Tokushima, Japan
  • 2007
    • Gifu Pharmaceutical University
      • Laboratory of Pharmaceutical Physical Chemistry
      Gihu, Gifu, Japan
  • 2001
    • Kinki University
      • Faculty of Medicine
      Ōsaka, Ōsaka, Japan
  • 1993-1995
    • Harvard Medical School
      Boston, Massachusetts, United States