72 research outputs found

    High Speed Turn-on Gate Driving for 4.5kV IEGT without Increase in PiN Diode Recovery Current

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    4.5 kV IEGT turn-on loss reduction is experimentally and numerically achieved by employing the proposed simple two step gate drive method without affecting PiN diode reverse recovery performance. It was found that 14% of turn-on loss is reduced only by the simple method. This study determines, for the first time, the optimum gate driving in the two step gate drive which can reduce IEGT turn-on loss maximally without affecting PiN diode reverse recovery performance by TCAD simulation. The method is simple yet effective for reducing switching loss of high voltage IEGT.2013 25th International Symposium on Power Semiconductor Devices & IC\u27s (ISPSD), May 26-30, 2013, Ishikawa Ongakudo, Kanazawa. Japan

    High Speed Turn-on Gate Driving for 4.5kV IEGT without Increase in PiN Diode Recovery Current

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    2013 25th International Symposium on Power Semiconductor Devices & IC's (ISPSD), May 26-30, 2013, Ishikawa Ongakudo, Kanazawa. Japan.4.5 kV IEGT turn-on loss reduction is experimentally and numerically achieved by employing the proposed simple two step gate drive method without affecting PiN diode reverse recovery performance. It was found that 14% of turn-on loss is reduced only by the simple method. This study determines, for the first time, the optimum gate driving in the two step gate drive which can reduce IEGT turn-on loss maximally without affecting PiN diode reverse recovery performance by TCAD simulation. The method is simple yet effective for reducing switching loss of high voltage IEGT

    Enterococcus hirae vacuolar ATPase is expressed in response to pH as well as sodium

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    AbstractThe Enterococcus hirae ntp operon encodes both a vacuolar ATPase, which transports Na+ as well as Li+, and the KtrII K+ transporter. A plasmid, in which the chloramphenicol acetyltransferase gene (CAT) was placed downstream of the ntp promoter, was introduced into a mutant totally defective in Na+ extrusion. The CAT activity of this transformant was increased preferentially by addition of NaCl, but not by LiCl, in the media or by elevating the medium pH, correlating well with the increase in amounts of the ATPase subunits observed by Western blotting. The physiological significance of these responses of the ntp promoter is discussed

    ヒト肝細胞癌においてherpesvirus entry mediatorの発現がもたらす影響

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    BACKGROUND: Herpes virus entry mediator (HVEM), also known as tumour necrosis factor receptor (TNFR) superfamily 14, regulates a variety of physiological and pathological responses in both innate and acquired immunity. Although HVEM is also suggested to be a critical regulator in tumours, actual roles in human cancer are largely unknown. This study aimed to clarify clinical importance of HVEM in human hepatocellular carcinoma (HCC). PATIENTS AND METHODS: We studied HVEM expression in 150 HCC patients to explore its clinical relevance, and we examined tumour infiltrating T cells and local immune status of them. RESULTS: HVEM was expressed in HCC cells, while no or only limited expression was observed in normal tissues in the liver. Tumour HVEM expression was significantly correlated with age, serum protein induced by vitamin K absence or antagonist-II (PIVKA-II) level, vascular invasion and tumour node metastasis (TNM) stage. Furthermore, tumour HVEM expression significantly correlated with postoperative recurrence and survival. Importantly, multivariate analysis indicated that the HVEM status had an independent prognostic value. Furthermore, HVEM status was inversely correlated with tumour-infiltrating CD4(+), CD8(+) and CD45RO(+) lymphocytes. In addition, it was also associated with reduced expression of perforin, granzyme B and interferon-γ (IFN-γ). Taken together, tumour-expressing HVEM plays a functionally important role in HCC. CONCLUSION: Tumour-expressing HVEM plays a critical role in human HCC, possibly through regulating immune evasion. Therefore, targeting HVEM may be a novel promising therapeutic strategy for HCC.博士(医学)・乙第1359号・平成27年5月28日Copyright © 2014 Elsevier Ltd

    PD-1とVEGFR2の同時阻害による相乗的抗腫瘍効果

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    Recent basic and clinical studies have shown that the programmed death ligand (PD-L)/PD-1 pathway has a significant role in tumour immunity, and its blockade has a therapeutic potential against several human cancers. We hypothesized that anti-angiogeneic treatment might augment the efficacy of PD-1 blockade. To this end, we evaluated combining the blockade of PD-1 and vascular endothelial growth factor receptor 2 (VEGFR2) in a murine cancer model using Colon-26 adenocarcinoma. Interestingly, simultaneous treatment with anti-PD-1 and anti-VEGFR2 monoclonal antibodies (mAbs) inhibited tumour growth synergistically in vivo without overt toxicity. Blocking VEGFR2 inhibited tumour neovascularization significantly, as demonstrated by the reduced number of microvessels, while PD-1 blockade had no impact on tumour angiogenesis. PD-1 blockade might promote T cell infiltration into tumours and significantly enhanced local immune activation, as shown by the up-regulation of several proinflammatory cytokine expressions. Importantly, VEGFR2 blockade did not interfere with T cell infiltration and immunological activation induced by PD-1 blockade. In conclusion, simultaneous blockade of PD-1 and VEGFR2 induced a synergistic in-vivo anti-tumour effect, possibly through different mechanisms that might not be mutually exclusive. This unique therapeutic strategy may hold significant promise for future clinical application.博士(医学)・甲第600号・平成25年5月29日発行元の猶予期間終了の後、本文を登録予定(2014.06

    ヒト膵癌におけるNectin-4発現の腫瘍増殖、血管新生に対する効果と臨床的意義

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    BACKGROUND: Nectin-4 belongs to the nectin family that has diverse physiological and pathological functions in humans. Recent studies have also suggested some roles for Nectin-4 in several human cancers. However, the precise roles and clinical relevance of Nectin-4 in tumors are largely unknown. METHODS: Nectin-4 expression was investigated in 123 patients with pancreatic cancer by immunohistochemistry. Furthermore, we investigated the association of Nectin-4 in pancreatic cancer with tumor proliferation, angiogenesis and immunity by using immunohistochemistry and siRNA interference method. RESULTS: Patients with high Nectin-4 expression had poorer postoperative prognosis than those with low expression. Importantly, multivariate analysis indicated that Nectin-4 expression had a significant independent prognostic value in pancreatic cancer (HR = 1.721, 1.085-2.730; P = 0.021). Tumor Nectin-4 expression was significantly correlated with Ki67 expression. In addition, siRNA-mediated gene silencing of Nectin-4 significantly inhibited the cell proliferation in human pancreatic cancer cells, Capan-2 and BxPC-3. Furthermore, Nectin-4 expression was also positively correlated with VEGF expression and intratumoral microvessel density. However, there were no significant correlations of tumor Nectin-4 expression with tumor-infiltrating T cells. CONCLUSION: Nectin-4 is a significant prognostic predictor, and may play a critical role in pancreatic cancer. Nectin-4 may be novel therapeutic target for pancreatic cancer.博士(医学)・乙第1400号・平成29年6月28日Copyright © Nishiwada et al.; licensee BioMed Central. 2015 : This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated

    Proximal nail fold flap for digital mucous cyst excision

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    The skin covering a digital mucous cyst is often very thin and is often excised with the cyst. Thus, transfer of a skin flap is needed for the defect. We have developed a proximal nail fold flap technique by which the thin skin covering the cyst can be preserved. We conducted a retrospective study to assess the effectiveness and reliability of this technique for digital mucous cyst excision. The study group comprised 26 patients treated for 28 digital mucous cysts. The flap was elevated on the nail matrix to expose the distal interphalangeal joint capsule. To preserve the skin in cases in which the skin covering the cyst was exceptionally thin, we did not excise the upper part of the cyst wall. Excision of the cyst and stalk was successful in all cases. Additional excision of the joint capsule or osteophyte(s) was achieved in 20 cases and 5 cases, respectively. No flap necrosis, skin defect or nail deformity resulted. Three of the cysts recurred and were treated successfully by reoperation involving the same flap elevation technique. We conclude that the proximal nail fold flap is useful for excision and reliable for wound coverage after digital mucous cyst excision
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