University 【 display / non-display 】

University 【 display / non-display 】

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Graduate School 【 display / non-display 】

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Research Areas 【 display / non-display 】

Published Papers 【 display / non-display 】

Published Papers 【 display / non-display 】

• One-Stage Cochlear Implantation for Adhesive Otitis Media

  Higa Teruyuki, Ganaha Akira, Kondo Shunsuke, Oyakawa Yoshiki, Agena Shinya, Hirakawa Hitoshi, Suzuki Mikio

  Practica Oto-Rhino-Laryngologica ( The Society of Practical Otolaryngology )  114 ( 12 ) 909 - 916   2021 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  <p>Cochlear implant surgery has been introduced successfully and is now one of the commonly performed surgeries. However, the surgical strategy of cochlear implantation in patients with chronic middle ear diseases, such as chronic otitis media and cholesteatoma, has not yet been fully established. In the present report, we describe the surgical technique adopted and prognosis of two patients with severe adhesive otitis media who underwent cochlear implant surgeries. Both underwent one-stage cochlear implantation combined with external auditory canal closure (blind-sac closure). Mastoidectomy with removal of the whole canal wall was performed to remove the otitis lesion thoroughly, and external auditory canal wall closure was performed to prevent recurrence of the lesion. A pneumatized tympanic cavity was observed and canal wall closure was maintained in both cases. Both patients acquired fair hearing ability with the cochlear implants. No severe complications have occurred until now, four years since the cochlear implantation. Although external ear canal closure destroys the natural structure of the external ear, one-stage cochlear implant surgery combined with canal closure is useful for elderly patients with systemic complications who desire shortening of hearing-deprived period.</p>

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• Measurement of stapes footplate thickness in otosclerosis by ultra-high-resolution computed tomography.

  Akazawa Y, Ganaha A, Higa T, Kondo S, Oyakawa Y, Hirakawa H, Suzuki M, Yamashiro T

  Acta oto-laryngologica ( Acta Oto-Laryngologica )  140 ( 11 ) 899 - 903   2020.11 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  BACKGROUND: Ultra-high-resolution computed tomography (U-HRCT) utilizes a 1024 × 1024 matrix with 0.25-mm section thickness, offering better spatial resolution than conventional multi-detector row CT to detect anatomic data for otologic surgery. AIMS: We examined stapes footplate thickness using U-HRCT in relation to stapedotomy to predict the difficulty of the surgical procedure. MATERIALS AND METHODS: Subjects were 12 otosclerosis patients and 25 controls who underwent diagnostic U-HRCT. A profile curve (Hounsfield units) was used to measure stapes footplate thickness along a perpendicular line across the stapes footplate in a plane parallel to the lateral semicircular canal. RESULTS: Footplate thickness was smaller at the midpoint than just before the anterior crus and just after the posterior crus. Interobserver variability was lowest at the midpoint, where foot plate thickness was significantly greater in the affected ear in otosclerosis patients compared with controls (0.60 ± 0.09 mm vs 0.46 ± 0.04 mm; p < .001). Otosclerosis patients were detected using U-HRCT with a high area under the curve. Difficulty in the stapes opening procedure correlated with stapes footplate thickness. CONCLUSIONS: Footplate thickness on U-HRCT correlated with temporal bone anatomy and corresponded to surgical difficulty. Significance: U-HRCT-derived anatomic data is useful for evaluating the stapes.

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• Up-regulation of DUSP5 and DUSP6 by gonadotropin-releasing hormone in cultured hypothalamic neurons, GT1-7 cells.

  Higa T, Takahashi H, Higa-Nakamine S, Suzuki M, Yamamoto H

  Biomedical research (Tokyo, Japan) ( バイオメディカルリサーチプレス )  39 ( 3 ) 149 - 158   2018 [ Peer Review Accepted ]

  Type of publication: Research paper (scientific journal)

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  <p>Gonadotropin-releasing hormone (GnRH) is secreted from hypothalamic neurons (GnRH neurons) and stimulates anterior pituitary gonadotrophs to synthesize and secrete gonadotropins. In addition to gonadotrophs, GnRH neurons also express GnRH receptors, and the autocrine action of GnRH is reportedly involved in the regulation of functions of GnRH neurons. There is accumulating evidence that extracellular signal-regulated kinase (ERK), one of mitogen-activated protein kinases (MAPKs), is activated by GnRH and involved in various effects of GnRH in GnRH neurons. In the present study, we performed microarray analysis to examine the types of genes whose expression was regulated by GnRH in immortalized mouse GnRH neurons (GT1-7 cells). We found that 257 genes among 55,681 genes examined were up-regulated after 30-min treatment of GT1-7 cells with GnRH. These up-regulated genes included four dual-specificity MAPK phosphatases (DUSPs), DUSP1, DUSP2, DUSP5, and DUSP6. Reverse transcription-polymerase chain reaction analysis confirmed that the mRNA levels of DUSP5 and DUSP6 were robustly increased within 30 min. U0126, an inhibitor of ERK activation, completely inhibited the increases in the mRNA levels of DUSP5 and DUSP6. Immunoblotting analysis revealed that ERK activation peaked at 5 min and declined steeply at 60 min, whereas DUSP5 and DUSP6 proteins were increased from 60 min. It was notable that down-regulation of DUSP6 augmented GnRH-induced ERK activation approximately 1.7-fold at 60 min. These results suggested that the up-regulation of DUSP6 regulates the duration of ERK activation at least in part.</p>

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