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413 results on '"Hibino, Hiroshi"'

101. In VivoReal-Time Simultaneous Examination of Drug Kinetics at Two Separate Locations Using Boron-Doped Diamond Microelectrodes

Author

Hanawa, Ai, Ogata, Genki, Sawamura, Seishiro, Asai, Kai, Kanzaki, Sho, Hibino, Hiroshi, and Einaga, Yasuaki

Abstract

Methylcobalamin, which is used for the clinical treatment of patients with neuropathy, can have an impact on the sensorineural components associated with the cochlea, and it is possible that the auditory threshold in a certain population of patients with deafness may be recovered. Nonetheless, it remains uncertain whether the action site of methylcobalamin is localized inside or outside the cochlea and which cellular or tissue element is targeted by the drug. In the present work, we developed a method to realize in vivoreal-time simultaneous examination of the drug kinetics in two separate locations using boron-doped diamond microelectrodes. First, the analytical performance of methylcobalamin was studied and the measurement protocol was optimized in vitro. Then, the optimized protocol was applied to carry out real-time measurements inside the cochlea and the leg muscle in live guinea pigs while systemically administering methylcobalamin. The results showed that the methylcobalamin concentration in the cochlea was below the limit of detection for the microelectrodes or the drug did not reach the cochlea, whereas the compound clearly reached the leg muscle.

Published
2020
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104. Expression of an inwardly rectifying [K.sup.+] channel, Kir4.1, in satellite cells of rat cochlear ganglia

Author

HIBINO, HIROSHI, HORIO, YOSHIYUKI, FUJITA, AKIKAZU, INANOBE, ATSUSHI, DOI, KATSUMI, GOTOW, TAKAHIRO, UCHIYAMA, YASUO, KUBO, TAKESHI, and KURACHI, YOSHIHISA

Subjects
Cochlea -- Research, Rats -- Physiological aspects, Ganglia -- Research, Immunohistochemistry -- Research, Neuroglia -- Research, Biological sciences
Abstract

Hibino, Hiroshi, Yoshiyuki Horio, Akikazu Fujita, Atsushi Inanobe, Katsumi Doi, Takahiro Gotow, Yasuo Uchiyama, Takeshi Kubo, and Yoshihisa Kurachi. Expression of an inwardly rectifying [K.sup.+] channel, Kir4.1, in satellite cells of rat cochlear ganglia. Am. J. Physiol. 277 (Cell Physiol. 46): C638-C644, 1999.--Satellite cells are glial cells wrapped around somata of sensory and autonomic ganglion neurons. Neither their functional roles nor electrical properties have been fully clarified so far. Using immunohistochemistry, we found that inwardly rectifying [K.sup.+] channel subunit Kir4.1 (also called Kirl.2 or [K.sub.AB]-2) was expressed prominently in the satellite cells of cochlear ganglia. The Kir4.1 immunoreactivity was localized specifically at the myelin sheaths of satellite cells wrapping the somata of the ganglion neurons. Developmental expression of Kir4.1 in satellite cells paralleled development of the action potential in the auditory nerve. These results suggest that this channel in satellite cells may be responsible for the regulation of [K.sup.+] extruded from the ganglion neurons during excitation. myelin sheaths; potassium-buffering action; immunohistochemistry; development; audition

Published
1999

107. Heterozygous mutation ofUsh1g/Sansin mice causes early-onset progressive hearing loss, which is recovered by reconstituting the strain-specific mutation inCdh23

Author

Miyasaka, Yuki, primary, Shitara, Hiroshi, additional, Suzuki, Sari, additional, Yoshimoto, Sachi, additional, Seki, Yuta, additional, Ohshiba, Yasuhiro, additional, Okumura, Kazuhiro, additional, Taya, Choji, additional, Tokano, Hisashi, additional, Kitamura, Ken, additional, Takada, Toyoyuki, additional, Hibino, Hiroshi, additional, Shiroishi, Toshihiko, additional, Kominami, Ryo, additional, Yonekawa, Hiromichi, additional, and Kikkawa, Yoshiaki, additional

Published
2016
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111. Negatively Charged Amino Acids Near and in Transient Receptor Potential (TRP) Domain of TRPM4 Channel Are One Determinant of Its Ca2+ Sensitivity.

Author

1000050596864, Yamaguchi, Soichiro, Tanimoto, Akira, 1000040344494, Otsuguro, Ken-ichi, 1000070314317, Hibino, Hiroshi, 1000040109509, Ito, Shigeo, 1000050596864, Yamaguchi, Soichiro, Tanimoto, Akira, 1000040344494, Otsuguro, Ken-ichi, 1000070314317, Hibino, Hiroshi, 1000040109509, and Ito, Shigeo

Abstract

Transient receptor potential (TRP) channel melastatin subfamily member 4 (TRPM4) is a broadly expressed nonselective monovalent cation channel. TRPM4 is activated by membrane depolarization and intracellular Ca2+, which is essential for the activation. The Ca2+ sensitivity is known to be regulated by calmodulin and membrane phosphoinositides, such as phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). Although these regulators must play important roles in controlling TRPM4 activity, mutation analyses of the calmodulin-binding sites have suggested that Ca2+ binds to TRPM4 directly. However, the intrinsic binding sites in TRPM4 remain to be elucidated. Here, by using patch clamp and molecular biological techniques, we show that there are at least two functionally different divalent cation-binding sites, and the negatively charged amino acids near and in the TRP domain in the C-terminal tail of TRPM4 (Asp-1049 and Glu-1062 of rat TRPM4) are required for maintaining the normal Ca2+ sensitivity of one of the binding sites. Applications of Co2+, Mn2+, or Ni2+ to the cytosolic side potentiated TRPM4 currents, increased the Ca2+ sensitivity, but were unable to evoke TRPM4 currents without Ca2+. Mutations of the acidic amino acids near and in the TRP domain, which are conserved in TRPM2, TRPM5, and TRPM8, deteriorated the Ca2+ sensitivity in the presence of Co2+ or PI(4,5)P2 but hardly affected the sensitivity to Co2+ and PI(4,5)P2. These results suggest a novel role of the TRP domain in TRPM4 as a site responsible for maintaining the normal Ca2+ sensitivity. These findings provide more insights into the molecular mechanisms of the regulation of TRPM4 by Ca2+.

Published
2014

112. Negatively Charged Amino Acids Near and in Transient Receptor Potential (TRP) Domain of TRPM4 Channel Are One Determinant of Its Ca2+ Sensitivity.

Author

Yamaguchi, Soichiro, Tanimoto, Akira, Otsuguro, Ken-ichi, Hibino, Hiroshi, Ito, Shigeo, Yamaguchi, Soichiro, Tanimoto, Akira, Otsuguro, Ken-ichi, Hibino, Hiroshi, and Ito, Shigeo

Abstract

Transient receptor potential (TRP) channel melastatin subfamily member 4 (TRPM4) is a broadly expressed nonselective monovalent cation channel. TRPM4 is activated by membrane depolarization and intracellular Ca2+, which is essential for the activation. The Ca2+ sensitivity is known to be regulated by calmodulin and membrane phosphoinositides, such as phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). Although these regulators must play important roles in controlling TRPM4 activity, mutation analyses of the calmodulin-binding sites have suggested that Ca2+ binds to TRPM4 directly. However, the intrinsic binding sites in TRPM4 remain to be elucidated. Here, by using patch clamp and molecular biological techniques, we show that there are at least two functionally different divalent cation-binding sites, and the negatively charged amino acids near and in the TRP domain in the C-terminal tail of TRPM4 (Asp-1049 and Glu-1062 of rat TRPM4) are required for maintaining the normal Ca2+ sensitivity of one of the binding sites. Applications of Co2+, Mn2+, or Ni2+ to the cytosolic side potentiated TRPM4 currents, increased the Ca2+ sensitivity, but were unable to evoke TRPM4 currents without Ca2+. Mutations of the acidic amino acids near and in the TRP domain, which are conserved in TRPM2, TRPM5, and TRPM8, deteriorated the Ca2+ sensitivity in the presence of Co2+ or PI(4,5)P2 but hardly affected the sensitivity to Co2+ and PI(4,5)P2. These results suggest a novel role of the TRP domain in TRPM4 as a site responsible for maintaining the normal Ca2+ sensitivity. These findings provide more insights into the molecular mechanisms of the regulation of TRPM4 by Ca2+.

Published
2014

115. NKCCs in the fibrocytes of the spiral ligament are silent on the unidirectional K+ transport that controls the electrochemical properties in the mammalian cochlea

Author

Yoshida, Takamasa, primary, Nin, Fumiaki, additional, Ogata, Genki, additional, Uetsuka, Satoru, additional, Kitahara, Tadashi, additional, Inohara, Hidenori, additional, Akazawa, Kohei, additional, Komune, Shizuo, additional, Kurachi, Yoshihisa, additional, and Hibino, Hiroshi, additional

Published
2014
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119. 1 聴覚はどのようにして起こるか（シンポジウム 難聴治療への取組, 第682回新潟医学会）

Author

日比野, 浩, Hibino, Hiroshi, 日比野, 浩, and Hibino, Hiroshi

Abstract

聴覚は, ヒトをはじめとした動物にとって不可欠な感覚である. 音は, 外耳を通り, 鼓膜や耳小骨からなる中耳を経て, 内耳の蝸牛に受容される. 現在, 日本では約数百万人が聴覚障害に苦しんでいるが, その多くは内耳の障害に起因する. 難聴患者数は, 高齢化社会を確実に迎える我国において増大するのは必至であり, 避けることのできない問題である. 従って, 難聴は克服すべき最優先課題の一つである. 難聴の病態解明や効果的な治療法の開発のためには, 蝸牛における音伝達機構を理解する必要がある. 蝸牛には, 音の周波数分析を行う仕組み, 音の機械的刺激を電気信号に変換する機能, 音シグナルを増幅する機構が備わっている. 本稿では, 哺乳類の蝸牛における音伝達のプロセスを紹介する.

Published
2013

120. 内耳を満たす特殊体液の電位環境の成立機序

Author

日比野, 浩, Hibino, Hiroshi, 日比野, 浩, and Hibino, Hiroshi

Abstract

聴覚は動物に必須である. 音は, 外・中耳を介して内耳蝸牛に到達し, 基底膜の振動として受容される. この機械的な刺激は, 聴覚の一次受容器である有毛細胞により電気信号に変換され, 脳へと伝達される. その際に, 蝸牛は, 内リンパ液と呼ばれる細胞外液の特殊な電位・イオン環境を用いて, 効率的かつ感受性高く有毛細胞を興奮させる. 従って内リンパ液環境は, 内耳機能に不可欠である. 本稿では, 高度に分化した基底膜と有毛細胞の機能を概略した後, 筆者の研究主題である内リンパ液環境の生理的役割と成立機構を紹介し, 内耳聴覚研究の面白さを示す.

Published
2011

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