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Kiyofumi Gyo

Publications and source records attributed to Kiyofumi Gyo.

13 recordsLinked to original sources
PubMed2003

AMPA/kainate-type glutamate receptor antagonist reduces progressive inner hair cell loss after transient cochlear ischemia.

We investigated the effect of glutamate receptor antagonists on progressive inner hair cell (IHC) loss following transient cochlear ischemia in gerbils. Transient cochlear ischemia was induced by 15-min bilateral vertebral artery occlusion. An alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/kainate-type glutamate receptor antagonist, 6-7-dinitroquinoxaline-2,3-dione (DNQX), or an N-methyl-D-aspartate (NMDA)-type receptor antagonist, MK-801, was administered 10 min before the ischemic insult. Hearing was assessed by sequentially recording compound action potentials (CAPs) before, during, and after the ischemia. The degree of hair cell loss in the organ of Corti was evaluated in specimens stained with rhodamine-phalloidin and Hoechst 33342. On the seventh day after ischemia, the increases in the CAP threshold and the progressive IHC loss were significantly reduced in cochleae treated with DNQX, while MK-801 was ineffective. These results suggest that the AMPA receptor plays a critical role in the development of the progressive IHC loss induced by ischemia/reperfusion injury in the cochlea.

Acoustic Stimulation↗
PubMed2003

Transient cochlear ischemia causes delayed cell death in the organ of Corti: an experimental study in gerbils.

To elucidate whether ischemia-reperfusion can cause delayed cell death in the cochlea, the effects of transient cochlear ischemia on hearing and on neuronal structures in the cochlea were studied in Mongolian gerbils. Ischemia was induced by bilaterally occluding the vertebral arteries for 5 minutes in gerbils, which lack posterior cerebral communicating arteries. In gerbils, the labyrinthine arteries are fed solely by the vertebral arteries. Occlusion of the vertebral arteries caused a remarkable increase in the threshold of compound action potentials (CAPs), which recovered over the following day. However, 7 days after the onset of reperfusion, the threshold began to increase again. Morphologic changes in the hair cell stereocilia were revealed by electron microscopy. The number of nuclear collapses was counted in cells stained for DNA and F-actin to evaluate the degree of cell death in the organ of Corti. Changes in spiral ganglion cell (SGC) neuron number were detected, whether or not progressive neuronal death occurred in the SGC. These studies showed that sporadic fusion of hair cells and the disappearance of hair cell stereocilia did not begin until 4 days after ischemia. On subsequent days, the loss of hair cells, especially inner hair cells (IHCs), and the degeneration of SGC neurons became apparent. Ten days after ischemia, the mean percentage cell loss of IHCs was 6.4% in the basal turn, 6.4% in the second turn, and 0.8% in the apical turn, respectively, and the number of SGC neurons had decreased to 89% of preischemic status. These results indicate that transient ischemia causes delayed hearing loss and cell death in the cochlea by day 7 after ischemia.

Action Potentials↗
PubMed2003

Effect of single-drug treatment on idiopathic sudden sensorineural hearing loss.

OBJECTIVES: In order to evaluate the effect of a medical administration for the sudden deafness patients, single-drug treatment for idiopathic sudden sensorineural hearing loss (ISSHL) was assessed at multi-centers participating in the Acute Severe Hearing Loss Study Group sponsored by the Ministry of Health, Labor and Welfare of Japan. METHODS: The subjects consisted of ISSHL patients who were (1) 20 years of age or older, (2) diagnosed within 2 weeks after the onset of hearing loss, (3) showing a mean hearing level of 40-90 dB at five frequencies from 250 to 4000 Hz, (4) previously untreated, and (5) with normal for age in hearing of the opposite ear. The drugs used in this study were ATP, alprostadil, hydrocortisone and amidotrizoate, which were administered intravenously, and beraprost sodium and betamethasone, which were given orally. Two drugs were assigned to each center, one of which was selected according to the code hidden in envelopes and administered for 1 week. The treatment after the single-drug administration was conducted at the discretion of each center. The hearing gain and recovery rate at 1 week after the initiation of single-drug treatment and at 1 month or over when the hearing level was fixed, were evaluated based on the criteria for hearing recovery prepared by the Acute Severe Hearing Loss Study Group. RESULTS: There was no statistically significant difference in the recovery rate among drugs either at 1 week after the initiation of single-drug treatment or at the time of fixed hearing level. At the time when the hearing level was fixed, a statistically significant difference in the complete recovery rate was detected only between amidotrizoate and beraprost sodium. CONCLUSION: From these results, we could not find any specific drugs recommended for ISSNHL. In evaluating the effect of the drugs, however, several problems in the clinical trial for ISSHL should be considered.

Adenosine Triphosphate↗
PubMed2003

A new method for closing tympanic membrane perforations using basic fibroblast growth factor.

OBJECTIVE: To present a new method for closing tympanic membrane perforations using basic fibroblast growth factor (bFGF) combined with an atelocollagen/silicone bilayer membrane as a patch material. STUDY DESIGN: Closure of tympanic membrane perforations was attempted using bFGF, which is thought to facilitate the growth of fibroblasts and collagen fibers at the margin of the perforation. METHODS: Under an operating microscope, the margin of the perforation was trimmed, and a piece of an atelocollagen/silicone bilayer membrane infiltrated with 0.2 mL Trafermin (0.1% solution) (bFGF group) or saline (control group) was then placed in the perforation with the silicon layer facing outward. Nine patients were treated with bFGF, and five were treated with saline. Data obtained from patient records included patient age, perforation size, and duration of treatment, with a focus on hearing improvement and complete tympanic membrane closure. RESULTS: The mean perforation size before treatment was 16.5% in the bFGF group and 9.6% in the control group. Closure of the tympanic membrane perforation was achieved in all cases in the bFGF group, whereas it was achieved in only two of five cases in the control group. With bFGF treatment, the tympanic membrane perforations closed completely within 3.7 weeks, and hearing improved by 13.3 dB in the bFGF group. CONCLUSION: The study demonstrated that bFGF combined with an atelocollagen/silicone bilayer membrane is effective for the conservative treatment of tympanic membrane perforation.

Adult↗
PubMed2003

Lateralization of the tympanic membrane as a complication of canal wall down tympanoplasty: a report of four cases.

OBJECTIVE: To describe the pathophysiology and treatment of the lateralized tympanic membrane that occurs after canal wall down tympanoplasty. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral hospital. PATIENTS: Four patients in whom lateralization of the tympanic membrane developed as a complication of canal wall down tympanoplasty. RESULTS: The patients had undergone middle ear surgery 20 to 34 years before their first visit to the authors. A Bondy operation with soft-wall reconstruction of the ear canal had been performed in three patients and a modified radical mastoidectomy in one patient. They all had severe conductive hearing loss. Common findings were anterior canal sulcus blunting, good tubal function, normal middle ear mucosa, and mobile stapes. At revision surgery, the lateralized tympanic membrane was removed, and the temporalis fascia was grafted medial to the malleus manubrium. The exposed bony surface in the ear canal was covered with a split-thickness skin graft, and the ear canal and the mastoid cavity were tightly packed to secure the graft. All the patients regained good hearing after the revision. Although deterioration of the anterior tympanic ring was presumed to be the primary cause of the graft lateralization, the lack of a posterior bony ear canal might have facilitated this condition. CONCLUSION: Lateralization of the tympanic membrane can occur even in an ear with a radicalized mastoid cavity, especially when the anterior tympanic ring is torn and the posterior ear canal is reconstructed with soft tissue.

Bone Conduction↗
PubMed2002

Apoptotic hair cell death after transient cochlear ischemia in gerbils.

The mechanisms of cochlear hair cell death following exposure to transient inner ear ischemia were investigated in gerbils histologically. The animals were subjected to ischemic insult by occluding both vertebral arteries for 15 min. Hoechst 33342 nuclear staining showed that inner hair cells (IHCs) underwent sporadic degeneration via nuclear condensation, which peaked 12 hours after the ischemia. Furthermore, nuclear DNA fragmentation was noted by the terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labeling method. Transmission electron microscopy revealed morphological changes in the IHCs characteristic of apoptosis, including karyopyknosis, chromatin condensation. These findings suggest that apoptotic cell death is the major process in hair cell degeneration in this animal model.

Animals↗
PubMed2002

Demyelination associated with HSV-1-induced facial paralysis.

In 1995, we developed an animal model of transient homolateral facial nerve paralysis by inoculating Herpes simplex virus type 1 (HSV-1) into the auricle of mice. This study examined the mechanism of facial nerve paralysis in this model histopathologically. Using the immunofluorescence technique with anti-HSV-1 antibody, the time course of viral spread and the site of viral replication were investigated over the entire course of the facial nerve. Furthermore, viral replication and nerve degeneration at the site of viral replication were observed by electron microscopy. On the 7th day after inoculation, facial paralysis was observed in more than 60% of mice. Immunofluorescence study revealed HSV-1 in the geniculate ganglion, the descending root, and the facial nucleus at this stage. On the 9th day, the descending root in the sections stained with osmium looked pale, because prominent demyelination had occurred in this region; electron micrographs showed many degenerated oligodendrocytes and large naked axons. In contrast, the facial nucleus neurons showed no remarkable degeneration, despite HSV-1 particles in their cytoplasm. From these findings, we concluded that facial nerve paralysis in this model is caused mainly by facial nerve demyelination in the descending root.

Animals↗
PubMed2002

Swelling of the intratemporal facial nerve in Ramsay Hunt syndrome.

Although Ramsay Hunt syndrome is one of the most important diseases causing peripheral facial palsy, the detailed pathology of the disease in the intratemporal facial nerve remains unclear. The purpose of this study was to increase knowledge of the pathogenesis of the syndrome by means of surgical findings. Between April 1976 and March 1997 we performed subtotal decompression of the facial nerve in 74 patients with severe Ramsay Hunt syndrome. The grade of nerve swelling was assessed using a microscope and recorded in a standardized form. The relationships between nerve swelling, the timing of surgery and the swelling of each segment were analyzed. Pronounced neural swelling, involving the geniculate ganglion and the horizontal segment, was consistent finding in the acute phase. Although the incidence of pronounced swelling of the horizontal segment gradually declined with time after onset, in most cases nerve swelling persisted even beyond the 16th week after onset. These data suggest that diffuse viral neuritis occurs throughout the intratemporal facial nerve. We assume that the viral inflammatory swelling involving the geniculate ganglion and horizontal segment is mostly responsible for the acute facial palsy in the acute phase.

Adult↗
PubMed2002

Labyrinthine fistula as a late complication of middle ear surgery using the canal wall down technique.

OBJECTIVES: To evaluate the clinical features of labyrinthine fistulae occurring as a late complication of middle ear surgery using the canal wall down technique. STUDY DESIGN: This was a retrospective study of the past 23 years, conducted at a single tertiary care center. The authors evaluated the backgrounds, clinical features, and surgical findings in 25 patients with labyrinthine fistulae, who had a history of ear surgery using the canal down technique and who underwent a second operation at their hospital. INTERVENTIONS: All the patients underwent revision surgery because of persistent or recurrent vertigo caused by labyrinthine fistulae, circumscribed labyrinthitis, or suppurative labyrinthitis. MAIN OUTCOME MEASURES: The clinical features of this disease entity were assessed by history, surgical findings, and the results of audiovestibular testing. RESULTS: The patients had a long history of repetitive postoperative aural discharge before experiencing vertigo, which initially occurred 4 to 64 years (average, 20.2 years) after the previous operation. At the first visit to the authors' clinic, the results of a fistula test conducted with a Politzer's bulb were positive in 14 patients and negative in 5 patients. In the remaining 6 ears, pressure loading of the ear canal induced the sensation of vertigo without accompanying nystagmus. Surgical intervention showed that the fistulae were located at the lateral semicircular canal in 19 ears, at the footplate of the stapes in 4 ears, and at the promontory in 2 ears. Labyrinthine fistulae were closed with conchal cartilage, bone paste (bone dust mixed with fibrin glue), and/or temporalis fascia. In some patients, the fistulae were further covered with pedicled temporalis muscle. In 2 cases complicated by acute suppurative labyrinthitis, the mastoid cavity was obliterated after completion of the labyrinthectomy. The postoperative courses in all patients were uneventful. CONCLUSIONS: A labyrinthine fistula may be created by repeated and insidious infection of a mastoid cavity that has been exposed to the outside during canal wall down surgery. Intensive care of the opened mastoid cavity is essential to avoid this late complication.

Adolescent↗
PubMed2002

Pathophysiology of facial nerve paralysis induced by herpes simplex virus type 1 infection.

Herpes simplex virus type 1 (HSV-1) has been proven to be a cause of Bell's palsy; however, the underlying pathophysiology of the facial nerve paralysis is not fully understood. We established a mouse model with facial nerve paralysis induced by HSV-1 infection simulating Bell's palsy and investigated the pathophysiology of the facial nerve paralysis. The time course of the R1 latency in the blink reflex tests paralleled the recovery of the facial nerve paralysis well, whereas electroneurographic recovery tended to be delayed, compared to that of the paralysis; these responses are usually seen in Bell's palsy. On histopathologic analysis, intact, demyelinated, and degenerated nerves were intermingled in the facial nerve in the model. The similarity of the time course of facial nerve paralysis and the electrophysiological results in Bell's palsy and the model strongly suggest that the pathophysiological basis of Bell's palsy is a mixed lesion of various nerve injuries.

Animals↗
PubMedDate not supplied

Ossicular reconstruction using hydroxyapatite prostheses with interposed cartilage.

PURPOSE: Despite the excellent biocompatibility of hydroxyapatite ossicular prostheses, extrusion of the prosthesis may be found during long-term follow-up, mainly due to the retraction of the eardrum. Although interposition of autologous cartilage between the eardrum and the prosthesis is empirically used to prevent extrusion, the clinical effect of this procedure has not been confirmed. The purpose of this study was to evaluate the effect of interposing a cartilage on the extrusion rate and hearing outcome. MATERIALS AND METHODS: Fifty-four ears in which cartilage was interposed with a hydroxyapatite prosthesis were compared with 53 ears without interposition. Three years after surgery, the otoscopic findings and hearing outcome were evaluated. RESULTS: The extrusion rate was 1.9% in the group with interposition and 13.2% in the group without interposition. The difference between the two groups was statistically different (chi(2) = 4.986; P =.03). There was no significant difference between the two groups in the postoperative air-bone gap. CONCLUSION: This procedure is an effective method for reducing the extrusion rate of hydroxyapatite prostheses without reducing the hearing gain resulting from ossiculoplasty.

Adolescent↗
PubMedDate not supplied

Chromametric assessment of nasal mucosal color and its application in patients with nasal allergy.

The color of the nasal mucosa was evaluated quantitatively in patients with nasal allergy and was compared with that in normal subjects. The chromaticity of the inferior turbinate was measured with the aid of a chromometer coupled with a light projection unit. Chromaticity was indicated by two parameters: the x and y values, which indicate the proportions of the red and green components of a color, respectively. Subjects included patients with Japanese cedar pollinosis (CP; n = 70) and perennial allergic rhinitis (PAR; n = 49), and normal subjects (n = 60). Mucosal blood flow in the inferior turbinate also was measured with a laser Doppler flowmeter in normal subjects. In normal subjects, the x value ranged between 0.4013 and 0.4539, and they value ranged between 0.3065 and 0.3379. The averages of the x and y values were 0.4264 +/- 0.0119 and 0.3204 +/- 0.0067, respectively. Age and sex were not related to the chromaticity value. Application of 0.1% epinephrine (0.12 mL) by aerosol spray decreased the x value significantly, in association with a significant decrease in blood flow in normal subjects. The x value of chromaticity in PAR patients was significantly lower than that in normal subjects; this showed the reduced red component of the color. There was no significant difference in the y value between PAR patients and the normal group. In the CP group, the x and y values were not significantly different from values in normal subjects. However, the x value in the first week after the onset of symptoms was significantly greater than that in the normal group. It subsequently decreased to the normal level in the second week and fell to a significantly lower level thereafter. This study found that the chromaticity of the nasal mucosa reflects local blood flow and that the circulatory dynamics in CP patients changes with time luring the pollinosis season.

Adolescent↗