Osamu Hashimoto

Kurume University, Куруме, Fukuoka, Japan

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Publications (262)461.5 Total impact

  • K Sasaki · Y Isimura · K Fujii · K Wake · S Watanabe · M Kojima · R Suga · O Hashimoto
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    ABSTRACT: Measurement of the dielectric properties of ocular tissues up to 110 GHz was performed by the coaxial probe method. A coaxial sensor was fabricated to allow the measurement of small amounts of biological tissues. Four-standard calibration was applied in the dielectric property measurement to obtain more accurate data than that obtained with conventional three-standard calibration, especially at high frequencies. Novel data of the dielectric properties of several ocular tissues are presented and compared with data from the de facto database.
    Physics in Medicine and Biology 08/2015; 60(16):6273-6288. DOI:10.1088/0031-9155/60/16/6273 · 2.76 Impact Factor
  • Shinya KITAGAWA · Ryosuke SUGA · Kiyomichi ARAKI · Osamu HASHIMOTO
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    ABSTRACT: Vertical- and horizontal-polarization RCS of a dipole antenna was reduced using a switchable reflector. The switchable reflector can switch reflection level for the vertical-polarization and have absorption for the horizontal-polarization. The reflection level of the reflector for the vertical-polarization can be switched using pin diodes and the reflection for the horizontal-polarization can be reduced using resistor on the surface. The switchable reflector was designed to operate at 9 GHz and fabricated. The vertical-polarized reflection coefficient was switched -28 dB with OFF-state diodes and -0.7 dB with ON-state diodes, and horizontal-polarized one was less than -18 dB at 9 GHz. The reflector with ON-state diodes was applied to an antenna reflector of a dipole antenna and comparable radiation pattern to that with a metal reflector was obtained at 9 GHz. Moreover the reflector with OFF-state diodes was applied to the reflector of the dipole antenna and the RCS of the dipole antenna was reduced 18 dB for the vertical-polarization and 16 dB for the horizontal-polarization. Therefore the designed switchable reflector can contribute to antenna RCS reduction for dual-polarization at the operating frequency without degrading antenna performance.
    IEICE Transactions on Electronics 01/2015; E98.C(7):701-708. DOI:10.1587/transele.E98.C.701 · 0.28 Impact Factor
  • Shinya Kitagawa · Ryosuke Suga · Osamu Hashimoto
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    ABSTRACT: A switchable reflector using pin diodes for the radar cross section (RCS) reduction of an antenna reflector was proposed. The reflection coefficient of the proposed reflector was able to be switched between less than -20 dB with OFF-state diodes and more than -0.8 dB with ON-state diodes around 9 GHz. The proposed reflector with ON-state diodes was applied to the reflector of a dipole array antenna and equivalent radiation pattern to one with a metal reflector was obtained. Moreover, it with OFF-state diodes reduces the antenna RCS more than 10 dB at 9 GHz. Therefore it can contribute to the antenna RCS reduction at the radiation frequency without degrading antenna performance.
    2014 15th International Radar Symposium (IRS); 06/2014
  • Shinya Kitagawa · Ryosuke Suga · Osamu Hashimoto
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    ABSTRACT: A switchable reflector using pin diodes for the radar cross section (RCS) reduction of an antenna reflector was proposed. The reflection coefficient of the proposed reflector was able to be switched between less than -25 dB with OFF-state diodes and more than -0.8 dB with ON-state diodes around 5 GHz. The proposed reflector with ON-state diodes was applied to a dipole antenna reflector and gave equivalent radiation pattern to with a metal reflector. It can contribute to the antenna RCS reduction at the radiation frequency without degrading antenna performance.
    2014 IEEE Radar Conference (RadarCon); 05/2014
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    ABSTRACT: Preclinical studies in rodent models of chronic liver fibrosis have shown that transplantation of peripheral blood (PB) CD34(+) cells leads to hepatic regeneration and a reduction of liver fibrosis by suppressing hepatic stellate cell activity and increasing matrix metalloproteinase activity. The aim of this study was to examine the safety and clinical efficacy of intrahepatic transplantation of autologous granulocyte-colony stimulating factor (G-CSF)-mobilized PB-CD34(+) cells in patients with decompensated liver cirrhosis. PB-CD34(+) cells were isolated from G-CSF-mobilized apheresis products. Ten patients were treated with G-CSF-mobilized PB-CD34(+) cells (treatment group) and 7 patients were treated with standard medical therapy. For mobilization, patients in the treatment group received subcutaneous injections of 10 μg G-CSF /kg/day for 5 days. The cells were then injected at three different doses (5×10(5) , 1×10(6) and 2×10(6) cells/kg) through the hepatic artery. Thereafter, all patients were followed-up for 24 months. G-CSF treatment and leukapheresis were well tolerated and no serious adverse events were observed. Patients in the treatment group had a significant but transient splenomegaly. After 24 weeks, serum albumin was significantly increased in patients who had received middle- or high-doses of CD34(+) cells compared to baseline. Doppler-US showed a significant increase in hepatic blood flow velocity and blood flow volume after CD34(+) cell therapy. The hepatic vein pressure gradient decreased in 2 patients who received high-dose CD34(+) cells at week 16. CD34(+) cell therapy is feasible, safe and effective in slowing the decline of hepatic reserve function.
    Journal of Gastroenterology and Hepatology 04/2014; 29(10). DOI:10.1111/jgh.12622 · 3.50 Impact Factor
  • Shinya Kitagawa · Ryosuke Suga · Osamu Hashimoto
    IEICE Transactions on Electronics 01/2014; E97.C(7):683-688. DOI:10.1587/transele.E97.C.683 · 0.28 Impact Factor
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    ABSTRACT: It is agreed that many of the antitumor effects of (-)-epigallocatechin gallate (EGCG) are mediated by various other effects. We report a new finding, namely, the antiproliferation potential and mechanism of methylated-(3'')-epigallocatechin gallate analog (MethylEGCG) having a stronger anti-oxidation effect than EGCG. MethylEGCG inhibited activity of vascular endothelial growth factor (VEGF)-depended VEGF receptor 2 and p42/44 MAPK, cell proliferation, and tube formation in human umbilical vascular endothelial cells (HUVECs) at 1 μ M. Even low- dose (1.1 mg/kg i.p. 8.3 mg/kg p.o.) administration suppressed tumor growth in xenografted Huh7 hepatoma mice by 50%. CD31 positive cells, visualized in blood vessels, were reduced in tumors by 18%, suggesting high antitumor activity via inhibition of angiogenesis. This study indicated that the modification of the 3'' position methylation of EGCG (MethylEGCG) could reduce cell growth effects at a low concentration in vivo.
    Nutrition and Cancer 09/2013; 66(4). DOI:10.1080/01635581.2013.783601 · 2.32 Impact Factor
  • Cancer Research 08/2013; 73(8 Supplement):890-890. DOI:10.1158/1538-7445.AM2013-890 · 9.33 Impact Factor
  • Journal of Hepatology 04/2013; 58:S130-S131. DOI:10.1016/S0168-8278(13)60313-X · 11.34 Impact Factor
  • K Sasaki · H Segawa · M Mizuno · K Wake · S Watanabe · O Hashimoto
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    ABSTRACT: The free space method using a pair of lens antennas was modified for the complex permittivity measurement of biological samples from 20 to 110 GHz. Two methodologies were used to obtain the complex permittivities by the free space method, which were based on the reflection and transmission coefficients. The measurement results obtained with the two methodologies were compared with each other. The measured complex permittivities of the biological samples from the free space method were then compared with those measured using the coaxial probe method. Finally, the measurement data were also compared with those from measurement methods developed in past literatures.
    Physics in Medicine and Biology 03/2013; 58(5):1625-33. DOI:10.1088/0031-9155/58/5/1625 · 2.76 Impact Factor
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    ABSTRACT: Background and AimIn cirrhosis, sinusoidal endothelial cell injury results in increased endothelin-1 (ET-1) and decreased nitric oxide synthase (NOS) activity, leading to portal hypertension. However, the effects of transplanted endothelial progenitor cells (EPCs) on the cirrhotic liver have not yet been clarified. We investigated whether EPC transplantation reduces portal hypertension. Methods Cirrhotic rats were created by the administration of carbon tetrachloride (CCl4) twice weekly for 10 weeks. From week 7, rat bone marrow-derived EPCs were injected via the tail vein in this model once a week for 4 weeks. Endothelial NOS (eNOS), vascular endothelial growth factor (VEGF) and caveolin expressions were examined by Western blots. Hepatic tissue ET-1 was measured by a radioimmunoassay (RIA). Portal venous pressure, mean aortic pressure, and hepatic blood flow were measured. ResultsEndothelial progenitor cell transplantation reduced liver fibrosis, α-smooth muscle actin-positive cells, caveolin expression, ET-1 concentration and portal venous pressure. EPC transplantation increased hepatic blood flow, protein levels of eNOS and VEGF. Immunohistochemical analyses of eNOS and isolectin B4 demonstrated that the livers of EPC-transplanted animals had markedly increased vascular density, suggesting reconstitution of sinusoidal blood vessels with endothelium. Conclusions Transplantation of EPCs ameliorates vascular dysfunction and portal hypertension, suggesting this treatment may provide a new approach in the therapy of portal hypertension with liver cirrhosis.
    Journal of Gastroenterology and Hepatology 01/2013; 28(1). DOI:10.1111/j.1440-1746.2012.07238.x · 3.50 Impact Factor
  • H. Onoue · N. Kamiya · R. Suga · O. Hashimoto
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    ABSTRACT: This paper presents a broadband metal-plate lens with a short focal length by considering radiated electric field near a primary radiator. The gain and radiation pattern of the proposed lens antenna was measured to be equivalent characteristics of a conventional lens antenna. As a result, the proposed lens can be moved 35 cm to the primary radiator compared with the conventional lens. Moreover, the gain of the proposed lens antenna is simulated to be higher than 20 dBi up to 10 GHz.
    Radar Conference (EuRAD), 2013 European; 01/2013
  • T. Suzuki · R. Suga · O. Hashimoto
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    ABSTRACT: In this paper, the transmission and leakage loss of post-wall waveguide depending on the thickness of porous substrate was evaluated. The transmission loss for various thickness of the porous waveguide was simulated in millimeter-wave band by using EM simulator. The valid substrate thickness for improving transmission loss by air-holes was studied. The leakage of the waveguide was also evaluated as a function of substrate thickness, and the relationship between transmission loss and leakage was discussed.
    Microwave Conference Proceedings (APMC), 2013 Asia-Pacific; 01/2013
  • IEICE Transactions on Electronics 01/2013; E96.C(1):77-83. DOI:10.1587/transele.E96.C.77 · 0.28 Impact Factor
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    ABSTRACT: Most of fundamental biological tissues and organs, such as skin, muscle, and brain, are wet and solid. Water evaporation on the sample surfaces generally deteriorates the measurement of complex permittivities, especially in quasi-millimeter wave and millimeter wave bands. This letter, therefore, introduces a new sample preparation procedure for avoiding the water-evaporation effect. This method is first validated with liquid biological tissue, i.e., whole blood, and then applied to a wet and solid biological tissue, i.e., crystalline lenses. The results show that the new method enables reproducible measurements of the complex permittivities of wet and solid biological samples.
    IEEE Transactions on Electromagnetic Compatibility 12/2012; 54(6):1298-1301. DOI:10.1109/TEMC.2012.2212443 · 1.30 Impact Factor
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    ABSTRACT: A new wideband wave absorber with translucent structure using carbon fibers is presented in this paper. The absorber is composed of bundled short carbon fibers which are arranged in front of a back metal and a spacer. Absorption characteristics of the one-layered absorber showed that matching frequencies can be controlled by the thickness of the spacer and the length of the carbon fibers. To further improve the characteristics, multi-layered absorbers are designed with the same procedure as one-layered absorber. The designed absorber showed 15 dB absorption characteristics from 1.0 to 10.0 GHz. Then a small anechoic chamber with the inside dimension of 200 cm x 200 cm x 200 cm was fabricated using ninety-six proposed absorbers. The electrical power in the chamber was measured at 2.45 GHz and the results showed that the variation of the power was less than 4 dB inside a circle with radius of 60 cm as work space for electromagnetic measurements.
    IEICE Transactions on Communications 12/2012; E95.B(12):3830-3836. DOI:10.1587/transcom.E95.B.3830 · 0.23 Impact Factor
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    ABSTRACT: VEGF, EGF, and TGF-α are expressed in hepatocellular carcinomas (HCC) and play a role in its growth. Vandetanib, a multikinase inhibitor, suppresses the phosphorylation of VEGF receptor 2 (VEGFR-2) and EGF receptor (EGFR). The aim of this study was to clarify the antitumor effect of vandetanib in mouse HCCs. We evaluated the effects of vandetanib on proliferation of human umbilical vein endothelial cells (HUVEC) and three hepatoma cell lines, as well as the phosphorylation of VEGFR-2 and EGFR in these cells. Mice were implanted with hepatoma cells subcutaneously or orthotopically in the liver and treated with 50 or 75 mg/kg vandetanib. We analyzed the effects of treatment on tumor cell proliferation and apoptosis, vessel density, phosphorylation of VEGFR-2 and EGFR, and production of VEGF, TGF-α, and EGF in tumor tissues. Adverse events on vandetanib administration were also investigated. Vandetanib suppressed phosphorylation of VEGFR-2 in HUVECs and EGFR in hepatoma cells and inhibited cell proliferation. In tumor-bearing mice, vandetanib suppressed phosphorylation of VEGFR-2 and EGFR in tumor tissues, significantly reduced tumor vessel density, enhanced tumor cell apoptosis, suppressed tumor growth, improved survival, reduced number of intrahepatic metastases, and upregulated VEGF, TGF-α, and EGF in tumor tissues. Treatment with vandetanib was not associated with serious adverse events, including alanine aminotransferase abnormality, bone marrow suppression, or body weight loss. The antitumor effects of vandetanib in mice suggest that it is a potentially suitable and safe chemotherapeutic agent for HCCs.
    Clinical Cancer Research 05/2012; 18(14):3924-33. DOI:10.1158/1078-0432.CCR-11-2041 · 8.72 Impact Factor
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    ABSTRACT: We investigated whether transplantation of purified human peripheral blood CD34(+) cells could reduce established liver fibrosis and up-regulate therapeutic regeneration. Human peripheral blood CD34(+) cells were isolated from total mononuclear cells of healthy volunteers by magnetic cell sorting. Recipient nude rats were injected intraperitoneally with carbon tetrachloride (CCl(4)) twice weekly for 3 weeks before single administration of CD34(+) cells. CCl(4) was then re-administered twice weekly for 3 more weeks, and the nude rats were sacrificed. Saline (control group), 1 × 10(5) (low-dose group), 5 × 10(5) (middle-dose group), or 2 × 10(6) (high-dose group) CD34(+) cells/kg body weight were intrasplenically transplanted after CCl(4) treatment for 3 weeks. Reverse transcriptase-polymerase chain reaction analysis of the freshly isolated CD34(+) cells revealed the expression of CD31, keratin19, α-smooth muscle actin (α-SMA), and epithelial growth factor, but not other liver related markers. The transplanted cells differentiated into vascular and sinusoidal endothelial cells, and vascular smooth muscle cells. CD34(+) cell transplantation reduced liver fibrosis in a dose-dependent fashion, with decreased collagen type-I and α-SMA-positive cells after 6 weeks of CCl(4) treatment by Mallory's Azan and immunohistochemical staining. Gelatin zymography showed that the expression levels of active matrix metalloproteinase-2 and -9 in CD34(+) cell transplanted livers were significantly stronger than those in saline-infused livers. In recipients of high-doses of CD34(+) cells, the number of PCNA-positive hepatocyte increased 6 weeks after CCl(4) treatment compared with saline-infused livers. We conclude that human peripheral blood CD34(+) cell transplantation halts established liver fibrosis and promotes hepatic regeneration in CCl(4)-induced chronic liver injury.
    Journal of Cellular Physiology 04/2012; 227(4):1538-52. DOI:10.1002/jcp.22873 · 3.84 Impact Factor
  • Takenori Yasuzumi · Yusuke Omote · Tomoki Uwano · Osamu Hashimoto
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    ABSTRACT: This paper presents an ultra-wideband (UWB) bandpass filter (BPF) with sharp attenuation slope characteristics. The circuit structure consists of an inter-digital finger resonator, parallel-coupled lines and phase matching line. The design of the bandwidth was described by using the even and odd mode characteristic impedances in the resonator structure. The parallel-coupled lines were also designed in the same manner. The parameters of the resonator and two parallel-coupled lines in combination as the BPF were then optimized by the simulation with HFSS. The designed BPF was experimentally fabricated and its measured performances showed the bandwidth from 3.6 to 10GHz with the 20dB outband rejection. For the U.S. UWB band design, the matching line was inserted between the two parallel-coupled lines. The matching at both band edges was then qualitatively analyzed on the smithchart. The HFSS simulation results of the structure realized the bandwidth from 3.1 to 10.6GHz with sharp attenuation slope characteristics for SWR < 2.0. The measurement results agree well with the simulation results.
    IEICE Transactions on Electronics 02/2012; 95-C(2):268-274. DOI:10.1587/transele.E95.C.268 · 0.28 Impact Factor
  • Takenori Yasuzumi · Tomoki Uwano · Osamu Hashimoto
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    ABSTRACT: A planar high-pass filter (HPF) by using cross-couplings in multi-layer structure is proposed in this paper. The HPF consists of parallel plate and gap type capacitors and inductor lines on the bottom conductor. The one block of the HPF has a ladder T-section in the bridge T configuration. The one block HPF is, thus, coarsely designed in the manner of the proto-type HPF and the performance is optimized by circuit simulator. With the gap capacitor adjusted the proposed HPF illustrates the steep slope characteristics near the cut-off frequency by the attenuation pole. In order to improve the stopband performance, the cascaded two block HPF is examined. Its measured results show the good agreement with the simulated ones giving the second attenuation pole by an inductive cross-coupling.
    IEICE Transactions on Electronics 02/2012; 95-C(2):313-316. DOI:10.1587/transele.E95.C.313 · 0.28 Impact Factor

Publication Stats

2k Citations
461.50 Total Impact Points


  • 1997–2014
    • Kurume University
      • • Research Center for Innovative Cancer Therapy
      • • Division of Gastroenterology
      • • Department of Pathology
      • • School of Medicine
      Куруме, Fukuoka, Japan
  • 1993–2014
    • Aoyama Gakuin University
      • • Department of Electrical Engineering and Electronics
      • • College of Science and Engineering
      • • Graduate School of Science and Engineering
      Edo, Tōkyō, Japan
  • 1998–2005
    • Kyushu University
      • Division of Cancer Genetics
      Hukuoka, Fukuoka, Japan
  • 2001–2004
    • Universität Stuttgart
      • Institute of Radio Frequency Technology
      Stuttgart, Baden-Württemberg, Germany
  • 2003
    • Social Insurance Chukyo Hospital
      Nagoya, Aichi, Japan
    • Yokohama Rubber Co. Ltd.
      Yokohama, Kanagawa, Japan
  • 1984–1985
    • Gifu University Hospital
      Gihu, Gifu, Japan