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Dive into the research topics where Hiroyuki Yamada is active.

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Featured researches published by Hiroyuki Yamada.


Otology & Neurotology | 2007

Valacyclovir and prednisolone treatment for Bell's palsy: a multicenter, randomized, placebo-controlled study.

Naohito Hato; Hiroyuki Yamada; Hisashi Kohno; Shuichi Matsumoto; Nobumitsu Honda; Kiyofumi Gyo; Satoshi Fukuda; Yasushi Furuta; Fumio Ohtani; Hiroshi Aizawa; Masaru Aoyagi; Hiroo Inamura; Tsutomu Nakashima; Seiichi Nakata; Shingo Murakami; Jun Kiguchi; Koji Yamano; Taizo Takeda; Masashi Hamada; Kazuhiro Yamakawa

Objective: To investigate the effects of valacyclovir and prednisolone in comparison with those of placebo and prednisolone for the treatment of Bells palsy, excluding zoster sine herpete. Study Design: Prospective, multicenter, randomized placebo-controlled study. Setting: Six academic tertiary referral centers. Patients: Ultimately, 221 patients with Bells palsy who were treated within 7 days of the onset. Serological and polymerase chain reaction examinations were performed to distinguish Bells palsy from zoster sine herpete. Intervention: The patients were treated with either valacyclovir (dosage, 1,000 mg/d for 5 days) plus prednisolone (VP [n = 114]) or placebo plus prednisolone (PP [n = 107]) administered orally. Main Outcome Measure: Recovery from the palsy was defined as a score higher than 36 using Yanagihara 40-point scoring system without facial contracture or synkinesis. The patients were followed up until complete recovery occurred or for more than 6 months in cases with a poor prognosis. Results: The overall rate of patient recovery among those treated with VP (96.5%) was significantly better (p < 0.05) than the rate among those treated with PP (89.7%). The rate of patient recovery was also analyzed by classifying the initial severity of facial palsy. In cases of complete or severe palsy, the rates of patients treated with VP and PP who recovered were 95.7% (n = 92) and 86.6% (n = 82), respectively; the recovery rate for treatment with VP was significantly better than that with PP (p < 0.05). Conclusion: The valacyclovir and prednisolone therapy was more effective in treating Bells palsy, excluding zoster sine herpete, than the conventional prednisolone therapy. To our knowledge, this is the first controlled study of an antiviral agent in the treatment of a sufficient number of Bells palsy cases based on an etiologic background.


Journal of Clinical Investigation | 2006

Induction of myasthenia by immunization against muscle-specific kinase

Kazuhiro Shigemoto; Sachiho Kubo; Naoki Maruyama; Naohito Hato; Hiroyuki Yamada; Chen Jie; Naoto Kobayashi; Katsurni Mominoki; Yasuhito Abe; Norifumi Ueda; Seiji Matsuda

Muscle-specific kinase (MuSK) is critical for the synaptic clustering of nicotinic acetylcholine receptors (AChRs) and plays multiple roles in the organization and maintenance of neuromuscular junctions (NMJs). MuSK is activated by agrin, which is released from motoneurons, and induces AChR clustering at the postsynaptic membrane. Although autoantibodies against the ectodomain of MuSK have been found in a proportion of patients with generalized myasthenia gravis (MG), it is unclear whether MuSK autoantibodies are the causative agent of generalized MG. In the present study, rabbits immunized with MuSK ectodomain protein manifested MG-like muscle weakness with a reduction of AChR clustering at the NMJs. The autoantibodies activated MuSK and blocked AChR clustering induced by agrin or by mediators that do not activate MuSK. Thus MuSK autoantibodies rigorously inhibit AChR clustering mediated by multiple pathways, an outcome that broadens our general comprehension of the pathogenesis of MG.


IEICE Transactions on Information and Systems | 2006

A Model for Detecting Cost-Prone Classes Based on Mahalanobis-Taguchi Method

Hirohisa Aman; Naomi Mochiduki; Hiroyuki Yamada

In software development, comprehensive software reviews and testings are important activities to preserve high quality and to control maintenance cost. However it would be actually difficult to perform comprehensive software reviews and testings because of a lot of components, a lack of manpower and other realistic restrictions. To improve performances of reviews and testings in object-oriented software, this paper proposes a novel model for detecting cost-prone classes; the model is based on Mahalanobis-Taguchi method---an extended statistical discriminant method merging with a pattern recognition approach. Experimental results using a lot of Java software are provided to statistically demonstrate that the proposed model has a high ability for detecting cost-prone classes.


Auris Nasus Larynx | 2011

Incidence of long-term ipsilateral and contralateral ototoxicity following radiotherapy for nasopharyngeal carcinoma.

Hiroyuki Wakisaka; Hiroyuki Yamada; Kazumi Motoyoshi; Toru Ugumori; Hirotaka Takahashi; Masamitsu Hyodo

OBJECTIVE To characterize the long-term adverse effects of radiotherapy on the ears in patients with nasopharyngeal carcinoma (NPC), we investigated ipsilateral and contralateral ototoxicities in the external, middle, and inner ear. METHODS The records of 48 ears in 24 radiotherapy-treated NPC patients were retrospectively analyzed. Radiotherapy doses varied between 60 and 70 Gy in 2-Gy fractions at 5 fractions/week. Ototoxicities were identified by otoscope and pure-tone audiograms conducted at 2-3 month intervals for ≥12 months. The relationship between radiation dosage and sensorineural threshold deterioration was statistically compared using the Mann-Whitney U-test. RESULTS Post-radiotherapy, 50% of all ears (3 of 6) that developed severe otitis externa were on the contralateral side. There was a post-radiotherapy increase in contralateral otitis media with effusion (OME) (1-7 ears), but a decrease in ipsilateral cases (16-12 ears), with 2 ears on either side subsequently developing chronic otitis media (COM). All ears that showed sensorineural hearing loss (SNHL) before radiotherapy exhibited a further threshold deterioration of more than 15 dB. No statistically significant difference (p=0.086) in average radiation dose was seen between ears with sensorineural threshold deterioration (50.0 Gy) and those without (48.2 Gy). CONCLUSION Long-term ototoxicity following radiotherapy for NPC can occur in either the ipsilateral or contralateral ears. Pathophysiology varies between and within each side. The post-therapy increase in OME on the contralateral side was thought to be due to radiotherapy-induced Eustachian tube damage, and the sensorineural threshold deterioration in at least 4 ears was thought to be due to chronic cochlea damage secondary to COM.


Laryngoscope | 2010

Facial synkinesis after experimental compression of the facial nerve comparing intratemporal and extratemporal lesions

Hiroyuki Yamada; Naohito Hato; Shingo Murakami; Nobumitsu Honda; Hiroyuki Wakisaka; Hirotaka Takahashi; Kiyofumi Gyo

The anatomical configuration of the facial nerve differs greatly between the intratemporal and extratemporal portions. The purpose of this study was to investigate the incidence of facial synkinesis and misdirection on clamping the facial nerve at the intratemporal or extratemporal portion of the facial nerve in guinea pigs.


Auris Nasus Larynx | 2003

A case of bilateral cervical lymph node metastasis of thyroglossal duct cancer

Hiroyuki Yamada; Akihiko Katoh; Hajime Ishinaga

UNLABELLED We reported a case of thyroglossal duct cancer, which metastasized to the bilateral cervical lymph nodes. The cervical lymph node metastases were detected in the upper portion of the neck. According to the results obtained in the preoperative fine needle aspiration cytology, the lymph node metastases were classified as group V and a diagnosis of papillary carcinoma was made. The preoperative studies with 123I revealed no concentration in the submittal tumor. In our surgical procedure, bilateral supraomohyoid neck dissection was added to excision of the tumor. CONCLUSION In view of the fact that thyroglossal duct cancer metastasized bilaterally to cervical lymph nodes in the present case, we experienced an extremely rare case.


Archives of Otolaryngology-head & Neck Surgery | 2013

Role of nitric oxide in the onset of facial nerve palsy by HSV-1 infection.

Naohito Hato; Hisashi Kohno; Hiroyuki Yamada; Hirotaka Takahashi; Kiyofumi Gyo

IMPORTANCE Although herpes simplex virus type 1 (HSV-1) is a causative agent of Bell palsy, the precise mechanism of the paralysis remains unknown. It is necessary to investigate the pathogenesis and treatment of Bell palsy due to HSV-1 infection. OBJECTIVE This study elucidated the role of nitric oxide (NO) in the incidence of facial nerve paralysis caused by HSV-1 in mice and to evaluate the possible role of edaravone, a free radical scavenger, in preventing the paralysis. DESIGN, SETTING, PARTICIPANTS Sixty-two mice served as animal models of Bell palsy in this laboratory study conducted at an academic institution. INTERVENTIONS Levels of NO in the facial nerve were measured using high-performance liquid chromatography and absorption photometry. The incidence of facial palsy was assessed following administration of edaravone immediately after HSV-1 inoculation and daily for 11 days thereafter. MAIN OUTCOMES AND MEASURES The ratio of NO (inoculated side to control side) and incidence of facial palsy. RESULTS Before the onset of facial palsy, no substantial difference in the NO level was noted between the HSV-1-inoculated side and the control side. When facial palsy occurred, usually at 7 days after inoculation, the NO level was significantly higher on the inoculated side than on the control side. Following recovery from the palsy, the high NO level of the inoculated side decreased. No increase in the NO level was observed in animals without transient facial palsy. When edaravone was administered, the incidence of facial palsy decreased significantly. CONCLUSIONS AND RELEVANCE These findings suggest that NO produced by inducible NO synthase in the facial nerve plays an important role in the onset of facial palsy caused by HSV-1 infection, which is considered a causative virus of Bell palsy. Hato and colleagues elucidate the role of nitric oxide in HSV-1–related facial nerve paralysis in mice and evaluate the role of edaravone, a free radical scavenger, in preventing the paralysis.


Auris Nasus Larynx | 2015

A case of hypertrophic cranial pachymeningitis associated with invasive Aspergillus mastoiditis

Masahiro Okada; Naohito Hato; Yoko Okada; Eriko Sato; Hiroyuki Yamada; Nobuhiro Hakuba; Kiyofumi Gyo

We report a rare case of hypertrophic cranial pachymeningitis (HCP) associated with invasive Aspergillus mastoiditis. A 63-year-old man with diabetes mellitus underwent mastoidectomy because of chronic discharge from his left ear. The mastoidectomy was unsuccessful in resolving purulent otorrhea; moreover, 7 months later, the patient developed left abducens nerve palsy. Magnetic resonance imaging revealed HCP at the left middle cranial fossa. Although the pathogen could not be identified, an Aspergillus infection was considered based on elevated serum β-d-glucan and a positive Aspergillus antigen test result. Voriconazole treatment resolved diplopia and left otorrhea and dramatically improved HCP.


IEICE Transactions on Information and Systems | 2005

A Simple Predictive Method for Discriminating Costly Classes Using Class Size Metric

Hirohisa Aman; Naomi Mochiduki; Hiroyuki Yamada; Matu-Tarow Noda

Larger object classes often become more costly classes in the maintenance phase of object-oriented software. Consequently class would have to be constructed in a medium or small size. In order to discuss such desirable size, this paper proposes a simple method for predictively discriminating costly classes in version-upgrades, using a class size metric, Stmts. Concretely, a threshold value of class size (in Stmts) is provided through empirical studies using many Java classes. The threshold value succeeded as a predictive discriminator for about 73% of the sample Java classes.


Experimental Gerontology | 2018

WITHDRAWN: Serum uric acid and prevalence of age-related hearing loss in the Japanese population: Baseline data from the Aidai Cohort Study in Yawatahama

Daiki Takagi; Shinya Furukawa; Masahiro Okada; Keiko Tanaka; Hidenori Senba; Masato Teraoka; Hiroyuki Yamada; Naohito Hato; Yoshihiro Miyake

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

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Hirohisa Aman

Center for Information Technology

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