H. Kobayashi

Tokyo Medical and Dental University, Edo, Tōkyō, Japan

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Publications (363)857.36 Total impact

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    ABSTRACT: Periodontitis is a multifactorial disease in which bacterial, lifestyle, and genetic factors are involved. Although previous genetic association studies identified several susceptibility genes for periodontitis in European populations, there is little information for Asian populations. Here, we conducted a genome-wide association study and a replication study consisting of 2,760 Japanese periodontitis patients and 15,158 Japanese controls. Although single-nucleotide polymorphisms that surpassed a stringent genome-wide significance threshold (P < 5 × 10(-8)) were not identified, we found 2 suggestive loci for periodontitis: KCNQ5 on chromosome 6q13 (rs9446777, P = 4.83 × 10(-6), odds ratio = 0.82) and GPR141-NME8 at chromosome 7p14.1 (rs2392510, P = 4.17 × 10(-6), odds ratio = 0.87). A stratified analysis indicated that the GPR141-NME8 locus had a strong genetic effect on the susceptibility to generalized periodontitis in Japanese individuals with a history of smoking. In conclusion, this study identified 2 suggestive loci for periodontitis in a Japanese population. This study should contribute to a further understanding of genetic factors for enhanced susceptibility to periodontitis. © International & American Associations for Dental Research 2015.
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    ABSTRACT: By monitoring coherent transition radiation (CTR) with a Michelson interferometer, bunch length measurement was investigated. Less-than-20-fs electron bunches were generated by a photocathode-based linear accelerator (linac) and a magnetic bunch compressor. From the femtosecond electron bunch of 2.1 pC and 32 MeV, CTR was measured using a Michelson interferometer that had two detectors with different spectral ranges, which enhanced the detection spectral range of CTR (ranging from 3 to 50 THz) and enabled us to determine the bunch length of the electron bunch. A model based on the interferometer's frequency sensitivity was proposed and introduced to analyze the measured interferograms. The measured interferograms and the frequency spectra were explained using the model.
    Physical Review Special Topics - Accelerators and Beams 07/2014; 17(7). DOI:10.1103/PhysRevSTAB.17.072803 · 1.52 Impact Factor
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    ABSTRACT: Objective: B7-H1 (CD274) is one of ligands for a co-inhibitory immunoreceptor PD-1. B7-H1 is induced on various non-lymphoid tissue cells as well as immune cells at inflammatory sites. We here investigated the roles of B7-H1 in the pathogenesis of acute and chronic periodontal tissue inflammation using murine models of gingivitis and periodontitis. Method: Wild type (wt), B7-H1/PD-1 double knockout (WKO), and B7-H1 transgenic (Tg) mice under the control of K14 promoter (B7-H1/K14tg) in the BALB/c background were used. Porphyromonas gingivalis (P.g, TDC 60) isolated from a patient with severe periodontitis was either topically painted or injected into the gingival tissues to induce acute and chronic periodontal tissue inflammation. Histology, cytokine expression by real-time PCR, TDC 60-specific serum IgG, and alveolar bone loss was examined. Result: In the B7-H1/K14tg mice, gingival epithelial cells expressed high levels of B7-H1. P.g enhanced histological infiltration and capillaries, and proinflammatory cytokine (IL-1b and TNF-a) expression in wt mice at acute phase (day 7), but these were inhibited in B7-H1/K14tg mice. In contrast, gingival inflammatory responses were markedly enhanced in the B7-H1/PD-1 WKO mice. At chronic phase (7 weeks), all groups of mice showed marked enhancement of P.g-specific total IgG, IgG1 and IgG2a production in serum. Wt and B7-H1/PD-1 WKO mice showed alveolar bone loss, but B7-H1/K14tg mice did not clearly exhibit alveolar bone loss. Conclusion: Our results suggest that B7-H1 overexpressed on gingival epithelial cells protect from acute and chronic gingival inflammation and alveolar bone loss.
    IADR Asia/Pacific Region (APR) Regional Meeting and Co-Annual Scientific Meeting of IADR Divisions 2013; 08/2013
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    ABSTRACT: Objectives: Periodontal disease is considered to be a risk factor for preterm low birth weight (PLBW), but underlying mechanisms have not yet been elucidated. The purpose of this study was to determine the presence of periopathogenic bacteria in placenta tissue and their effect on pregnancy outcomes. Methods: Oral (plaque and saliva) and placenta samples were taken from 13 women who had PLBW deliveries, compared with 51 samples from full term and healthy weight deliveries. The periodontal parameters were recorded. A. actinomycetemcomitans and P. gingivalis were identified both in placenta samples and oral samples by using polymerase chain reaction. Serum antibodies of A. actinomycetemcomitans and P. gingivalis were detected by using enzyme linked immune sorbent assay. Results: PLBW group had significant higher oral P. gingivalis detection frequency than healthy delivery group. Of 64 subjects, 3 subjects had placenta with P. gingivalis positive, 2 of them were in PLBW group and also with oral P. gingivalis positive. Antibody against P. gingivalis was higher in PLBW group than in healthy delivery group. Two subjects in healthy delivery group were detected with oral A. actinomycetemcomitans, one of them also detected with A. actinomycetemcomitans in placenta. Conclusions: Present study suggested that P. gingivalis and A. actinomycetemcomitans may colonize in placenta tissue and infection with P.gingivalis and its antibody might be a risk factor for PLBW.
    IADR/AADR/CADR General Session and Exhibition 2013; 03/2013
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    ABSTRACT: Objectives: The Er:YAG laser has been effectively applied in periodontal therapy. Previous studies reported that low-level laser irradiation promotes cell proliferation and wound healing. However, the mechanisms still remain unclear. In the present study, we analyzed the differential protein expression in human gingival fibroblasts (HGFs) following low-level Er:YAG laser irradiation by proteomic analysis, providing basic evidence on mechanisms of photobiomodulatory effects. Methods: HGFs were obtained from outgrowth culture of gingival tissue. Following 24 h subculture, serum starvation was carried out with 0.5% FBS DMEM for 24 h. The cells were treated with low-level Er:YAG laser irradiation with various energy densities. On day 3, cell proliferation and damage were evaluated by WST-8 assay and lactate dehydrogenase (LDH) levels. Proteomic analysis was also performed using HGFs 24 h after irradiation. Peptides were enzymatically digested from HGFs, and after purification, they were analyzed by a hybrid ion-trap Fourier transform mass spectrometer (LC/MS/MS). The MASCOT search engine was used to identify proteins from the mass and tandem mass spectra of peptides. Peptide mass data were matched by searching the UniProtKB database. Also, some of the expression-increased proteins in the cells were quantified following irradiation by real time RT-PCR and Western blotting. Results: A significant increase in cell proliferation was observed following irradiation without increasing LDH level. Approximately three hundred proteins were identified in HGFs by LC/MS/MS. Among these, over 60 proteins showed change in expressions, and out of the 60 proteins, several ones, such as Galectin-7, which are reportedly associated with the process of wound healing were included. In the irradiated HGFs, mRNA and protein level of Galectin-7 were increased. Conclusions: The results indicate that low-level Er:YAG laser irradiation promotes HGFs proliferation and the change in expression of various proteins in HGFs following irradiation may partly contribute to the increased cell proliferation.
    IADR/AADR/CADR General Session and Exhibition 2013; 03/2013
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    ABSTRACT: The magnetoresistance of λ-(BETS)2FeCl4 was measured along the needle axis of the crystal to determine the pressure and magnetic field dependences of the coupled metal-insulator and antiferromagnetic transition temperature (TMI, TN). TMI decreases when applying pressure and/or magnetic field. The TMI vs H curve shows an inflection point (H1). The anomaly observed around 1 T (H1) corresponds to the spin-flop transition observed by the SQUID measurements. The magnetization (M) of the oriented polycrystalline sample of λ-(BETS)2FeCl4 was measured at 2–15 K in a magnetic field of 0.01–7 T. The magnitude of the characteristic drop of M observed for the field parallel to the c axis (ΔM∥) becomes small above 1.2 T but remains almost constant above 4.5 T.
    Solid State Communications 01/2013; DOI:10.1016/S0038-1098(97)10189-2 · 1.70 Impact Factor
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    ABSTRACT: Magnetic torque measurements have been carried out for two-dimensional magnetic-field-induced organic superconductor λ-(BETS)2FeCl4, where BETS stands for bis(ethylenedithio)tetraselenafulvalene, to investigate the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. The in-plane upper critical field of the field-induced-superconducting phase steeply decreases with decreasing temperature below 2.2 K. The in-plane field dependence of the diamagnetic susceptibility shows a significant decrease below 25 T at low temperatures, showing that magnetic fluxes are less excluded from the sample. These results show the presence of the FFLO phase with the tricritical point between the FFLO, homogeneous superconducting, and paramagnetic metallic phases at 2.2 K and 23 T. The stability of the FFLO phase is also investigated as a function of the magnetic field angle and compared with theories.
    Physical review. B, Condensed matter 05/2012; 85(17). DOI:10.1103/PhysRevB.85.174530 · 3.66 Impact Factor
  • Y. Tobe, S. Imaizumi, N. Aoki, H. Kobayashi
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    ABSTRACT: In this paper, an efficient data hiding scheme for printed color images is proposed that visualizes on printed color images embedded data that is invisible on a monitor. We accomplished this scheme by using the differences of color gamut between a monitor and printer. The proposed scheme visualizes embedded data by converting one piece of color information, either L*, a*, or b*, to a fixed value when printing. This feature can be easily applied to copyright protection for printed images. Simulation results show the effectiveness of our scheme.
    Intelligent Signal Processing and Communications Systems (ISPACS), 2012 International Symposium on; 01/2012
  • S. Imaizumi, N. Aoki, H. Kobayashi, H. Kiya
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    ABSTRACT: We propose a key assignment scheme and applying it to control hierarchical access to multimedia content. By introducing a modified hash chain, the proposed scheme manages one key composed of a single segment. The managed key is not distributed to any users, providing security against key leakage. Collusion attacks are prevented by the order of key assignment. Our scheme also reduces the number of hash calculations. Analysis of performance demonstrated this scheme is valid.
    Intelligent Information Hiding and Multimedia Signal Processing (IIH-MSP), 2012 Eighth International Conference on; 01/2012
  • H. Kobayashi, M. Iwahashi, H. Kiya
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    ABSTRACT: This paper proposes an extended median cut quantization method with special median values, which does not have a restriction that the number of signals after quantization is a power of 2. The proposed quantization performs fast and the quantization error of it becomes smaller than that of the linear quantization for images with sparse histogram. When the number of the quantization levels is large, it is confirmed that the quantization error of the proposed quantization becomes smaller than the median cut quantization, and becomes almost the same as the Lloyd-Max quantization for general images. Finally, we apply to a high bit rate lossy data compression system for sparse histogram images using the proposed quantization.
    Intelligent Signal Processing and Communications Systems (ISPACS), 2012 International Symposium on; 01/2012
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 12/2010; 24(50). DOI:10.1002/chin.199350325
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    ABSTRACT: A deposition from binary vapors (DBV) has been developed into a novel technique for the growth of polycrystalline thin films of SrGa2S4 by employing simultaneous evaporation of gallium sulfide (Ga2S3) and cerium-activated strontium sulfide (SrS). The growth kinetics of SrGa2S4 was studied by investigating the crystallographic structure and composition of evaporated films as a function of the substrate temperature and impingement flux ratio with the aid of energy-dispersive x-ray microanalysis and x-ray diffraction measurements. With regard to uniform crystalline structure and stoichiometric compositiion, a Ca2S3/SrS flux ratio in the 60 to 100 range was empirically found to give the best results for a substrate temperature of 460 degrees C. The Ce-doped SrGa2S4 films exhibit the characteristic photoluminescent emission which is dominated by the D-2-F-2(5/2) transition within the Ce3+ ions occurring at 445 nm in the blue region.
    ChemInform 10/2010; 28(43). DOI:10.1002/chin.199743007
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    ABSTRACT: Objectives: Wnt signaling molecules play important roles in bone biology, apoptosis, chronic inflammation and wound healing. Recent studies have suggested an association of these molecules with various disorders including cardiovascular diseases, rheumatoid arthritis, and osteoarthritis. We previously demonstrated that Wnt5a mRNA expression was upregulated in chronic periodontitis tissue when compared to non-periodontitis tissue. In this study, we investigated the modulation of Wnt5a mRNA expression by periodontopathic bacteria. Methods: Human monocytic cell line THP-1 cells were stimulated with Porphyromonas gingivalis, its lipopolysaccharide (LPS), Aggregatibacter actinomycetemcomitans, TNF-a and IFN-g. To investigate the involvement of NF-kB and JAK/STAT pathways in the modulation of Wnt5a expression, techniques were used including inhibition assay, transfection, luciferase assay, and EMSA. The levels of Wnt5a mRNA were determined by real-time RT-PCR. Results: P. gingivalis LPS upregulated Wnt5a and NF-kB expression in THP-1 cells. P. gingivalis LPS-induced Wnt5a mRNA levels were suppressed by a JAK/STAT inhibitor (AG490), a STAT1 inhibitor (fludarabine) and two different NF-kB pathway inhibitors. Furthermore, the induction of Wnt5a mRNA expression was augmented by co-stimulation with IFN-g and overexpression of STAT1, but was suppressed by STAT1 siRNA. Conclusion: Our study suggests that Wnt5a upregulation by P. gingivalis LPS in THP-1 cells is dependent upon NF-kB and STAT1. The modulation of Wnt5a expression by P. gingivalis may play an important role in the periodontal inflammatory process. (This study was supported by grants from the Japanese Ministry of Education (GCOE) Program, International Research Center for Molecular Science in Tooth and Bone Diseases, and the JSPS Invitation Fellowship for Research in Japan)
    IADR General Session 2010; 07/2010
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 07/2010; 27(27). DOI:10.1002/chin.199627157
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    ABSTRACT: Shubnikov–de Haas and angular dependent magnetoresistance oscillations have been used to explore the role of anion size, magnetic moment, and disorder in the organic conductors κ‐(BETS)2GaBr4κ‐(BETS)2GaBr4 and κ‐(BETS)2FeCl2Br2κ‐(BETS)2FeCl2Br2 in the isomorphic class κ‐(BETS)2Ga1‐xFexCl4‐yBryκ‐(BETS)2Ga1‐xFexCl4‐yBry. The results, combined with previous work, show correlations between the anion composition (Ga1‐xFexCl4‐yBry)(Ga1‐xFexCl4‐yBry) and the superconducting transition temperature, effective mass, Fermi surface topology, and the mean free path.
    Physica B Condensed Matter 06/2010; 405(11):S295–S298. DOI:10.1016/j.physb.2009.11.050 · 1.28 Impact Factor
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    ABSTRACT: The four-probe resistivity measurements were performed on the molecular crystals of TMTTeN (=tetramethyltetratelluronaphthalene) and [Ni(ptdt)2] (ptdt=propylenedithio tetrathiafulvalenedithiolate) by using a diamond anvil cell (DAC) up to 30 and 21GPa, respectively. In spite of extremely large enhancement of room-temperature conductivity (∼350Scm−1 at 25.4GPa) and metallic behavior at low temperatures (25–65K at 25.4GPa), the pressure-induced metallic state could not be observed in TMTTeN up to 30GPa at least around room temperature. The resistivity of [Ni(ptdt)2] decreased with increasing pressure and became approximately 10−2Ωcm at 18Gpa. The temperature dependence of the resistivity exhibited a weakly semiconducting behavior. At around 19.5GPa, [Ni(ptdt)2] showed weakly metallic behavior down to low temperature. However, this pressure-induced metallic state was not stable. At 20.7GPa, the resistivity increased again below 40K.The four-probe resistance measurements were also performed on the extremely brittle thin-plate microcrystals of single-component antiferromagnetic molecular conductor [Au(tmdt)2]. The resistance (R) decreased continuously with decreasing temperature (T). Except for a slight bending of the R−T curve at around the magnetic transition temperature (TN=110K), no resistance anomaly was observed. Nonetheless, the existence of the metallic state below TN was confirmed for the first time from the results of single-crystal resistance measurement.The precise crystal structure examinations were performed on [Au(tmdt)2] by the powder X-ray diffraction data at the temperature range of 9–300K.
    Physica B Condensed Matter 06/2010; 405(11). DOI:10.1016/j.physb.2010.02.004 · 1.28 Impact Factor
  • H. TANAKA, A. KOBAYASHI, H. KOBAYASHI
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 05/2010; 29(18). DOI:10.1002/chin.199818285
  • H. B. Cui, D. Graf, J. S. Brooks, H. Kobayashi
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    ABSTRACT: A Reply to the Comment by Dafang Li, Yanming Ma, and Jun Yan.
    Physical Review Letters 04/2010; 104(13). DOI:10.1103/PhysRevLett.104.139702 · 7.73 Impact Factor
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    ABSTRACT: Periodontitis is a chronic inflammatory disease characterized by the enhanced expression of inflammatory mediators leading to alveolar bone resorption. Osteoprotegerin (OPG) plays a suppressive role in cytokine-induced osteoclastogenesis. In osteoblasts, OPG expression is upregulated by beta-catenin but downregulated by the transcription factor activator protein-1 (AP-1; c-fos/c-jun). The purpose of this study was to examine the roles of beta-catenin and AP-1 in interleukin-1alpha (IL-1alpha) -induced OPG production in human gingival fibroblasts (hGFs) and periodontal ligament (PDL) cells. Expression of c-fos and c-jun messenger RNA was measured by reverse transcription-polymerase chain reaction and OPG production was analysed by enzyme-linked immunosorbent assay. The nuclear AP-1 activity was quantified using an AP-1 microplate assay. The effect of the Wnt canonical pathway on OPG production was evaluated using small interfering (si) RNA for beta-catenin and the effect of AP-1 on OPG production was evaluated using the AP-1 inhibitor curcumin. Levels of c-fos messenger RNA and nuclear AP-1 activity were higher in PDL cells than in hGFs. When stimulated with IL-1alpha, PDL cells had significantly higher c-fos expression and lower OPG production compared with hGFs. The siRNA for beta-catenin suppressed the IL-1alpha-induced OPG production in both PDL cells and hGFs, whereas the AP-1 inhibitor curcumin augmented the IL-1alpha-induced OPG production in PDL cells, but not in hGFs. The present study suggests that beta-catenin enhances IL-1alpha-induced OPG production in both PDL cells and hGFs, whereas AP-1 suppresses IL-1alpha-induced OPG production in PDL cells. Higher expression of c-fos in PDL cells than in hGFs may implicate a role of PDL cells in alveolar bone resorption in periodontitis.
    Oral Microbiology and Immunology 11/2009; 24(5):384-9. DOI:10.1111/j.1399-302X.2009.00529.x · 2.81 Impact Factor
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    ABSTRACT: Shubnikov-de Haas and angular dependent magnetoresistance oscillations have been used to explore the role of anion size, magnetic moment, and disorder in the organic conductors kappa-(BETS)_2GaBr_{4} and kappa-(BETS)_2FeCl_{2}_Br_{2} in the isomorphic class kappa-(BETS)_2Ga_{1-x}Fe_{x}Cl_{4-y}_Br_{y}. The results, combined with previous work, show correlations between the anion composition (Ga_{1-x}Fe_{x}Cl_{4-y}_Br_{y}) and the superconducting transition temperature, effective mass, Fermi surface topology, and the mean free path. Comment: 5 pages, 6 figures

Publication Stats

5k Citations
857.36 Total Impact Points

Institutions

  • 1997–2015
    • Tokyo Medical and Dental University
      • • Department of Periodontology
      • • Department of Internal Medicine
      Edo, Tōkyō, Japan
    • Saitama Cancer Center
      Saitama, Saitama, Japan
  • 2014
    • Osaka University
      • Institute of Scientific and Industrial Research
      Suika, Ōsaka, Japan
  • 2013
    • Health Sciences University of Hokkaido
      • Department of Periodontology and Endodontology
      Tōbetsu, Hokkaidō, Japan
  • 2012–2013
    • Chiba University
      • • Department of Molecular Diagnosis
      • • Graduate School of Advanced Integration Science
      Tiba, Chiba, Japan
  • 2009–2012
    • Nihon University
      • Department of Chemistry
      Edo, Tōkyō, Japan
  • 1998–2010
    • Tottori University
      • Department of Electrical and Electronic Engineering
      TTJ, Tottori, Japan
  • 1984–2010
    • Toho University
      • • Department of Chemistry
      • • Faculty of Science
      Edo, Tōkyō, Japan
  • 2006–2008
    • Tokushima Bunri University
      Tokusima, Tokushima, Japan
    • Jichi Medical University
      • Division of Endocrinology and Metabolism
      Totigi, Tochigi, Japan
  • 2007
    • Khon Kaen University
      • Faculty of Dentistry
      Kawn Ken, Khon Kaen, Thailand
  • 1991–2007
    • Institute for Molecular Science
      Okazaki, Aichi, Japan
    • Utsunomiya University
      • Division of Electrical and Electronic Engineering
      Totigi, Tochigi, Japan
    • Paul Sabatier University - Toulouse III
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 1999–2006
    • Rikkyo University
      • Institute for Atomic Energy
      Edo, Tōkyō, Japan
    • Shinshu University
      Shonai, Nagano, Japan
    • Tokyo Women's Medical University
      • Department of Urology
      Edo, Tōkyō, Japan
  • 2005
    • Japan Science and Technology Agency (JST)
      Edo, Tōkyō, Japan
    • Japan Red Cross Fukuoka Hospital
      Hukuoka, Fukuoka, Japan
  • 2004
    • Hokkaido University
      Sapporo, Hokkaidō, Japan
  • 2003
    • Nagoya University
      Nagoya, Aichi, Japan
    • Pioneer Corporation
      Kawasaki Si, Kanagawa, Japan
    • Kyoto University
      Kioto, Kyōto, Japan
  • 2001–2003
    • Florida State University
      • Department of Physics
      Tallahassee, Florida, United States
    • Tsukuba Research Institute
      Edo, Tōkyō, Japan
  • 1983–2003
    • The University of Tokyo
      • Institute for Solid State Physics
      Tōkyō, Japan
  • 1998–2001
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 2000
    • University of Malaya
      • Department of Physics
      Kuala Lumpur, Kuala Lumpur, Malaysia
    • Nippon Zenyaku Kogyo Co., Ltd.
      Hukusima, Fukushima, Japan
  • 1995–2000
    • High Energy Accelerator Research Organization
      • Accelerator Laboratory
      Tsukuba, Ibaraki-ken, Japan
  • 1996
    • Tokai University
      • School of Medicine
      Hiratuka, Kanagawa, Japan
  • 1993–1995
    • Gakushuin University
      • Department of Physics
      Edo, Tōkyō, Japan
    • Tokyo University of Science
      Edo, Tōkyō, Japan
    • Niigata University
      • Division of Neuropathology
      Niahi-niigata, Niigata, Japan