Publications (15) View all
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Article: WDR1 expression in normal and noise-damaged sprague-dawley rat cochleae.
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ABSTRACT: WD40 repeat protein 1 (WDR1) has been suggested as a protective mechanism or a sign of regeneration in avian cochlea. However, its role in mammalian cochlea has yet to be determined. Hence we investigated WDR1 expression in sound-overstimulated Sprague-Dawley rats. Rats were divided into 3 groups [the permanent- and temporary threshold shift (PTS and TTS) groups and the control group], according to the extent of noise exposure and euthanized immediately, 3- or 7 days after noise exposure for cochlear harvest. Immunocytochemistry localized WDR1 to outer hair cells, Deiter's cells, outer sulcus cells and Reissner's membrane in the control group, and the PTS and TTS groups exhibited stronger WDR1 expression in the same cochlear regions than the controls. Moreover, WDR1 expression in these noise-exposed groups was extended to inner hair cells and basal cells of the stria vascularis. The expression of WDR1 in the PTS and TTS groups showed differences in intensity and shifts of localization, based on exposure length and recovery duration. Contrary to the avian cochlea, hair cell regeneration does not naturally occur in the acoustically damaged mammalian cochlea. Therefore, elevated WDR1 expression after acoustic overstimulation in the current experiments may provide a mechanism for protection against noise exposure. J. Comp. Neurol., 2012. © 2012 Wiley Periodicals, Inc.The Journal of Comparative Neurology 07/2012; · 3.81 Impact Factor -
Article: Increased activity of mitochondrial respiratory chain complex in noise-damaged rat cochlea.
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ABSTRACT: Functional changes of mitochondrial respiratory chain (MRC) and hearing threshold shifts were observed after noise exposure and the pattern was different depending on the extent of the noise damage. The aim of this study was to reveal any functional changes of the MRC enzyme in outer hair cells after noise damage. Sprague-Dawley rats were used and divided into three groups including normal control group and noise exposure for 1 h and 5 h. White band noise was used with 120 dB SPL. We measured hearing threshold and activity of succinate dehydrogenase (SDH) before noise exposure, and immediately and 1, 3, 7, and 14 days after noise exposure in each group. Immunostaining using monoclonal anti-MRC complex V subunit α was performed. Transmission electron microscopy (TEM) was carried out. The hearing threshold level changed depending on the exposure time in both the noise-exposed groups. In the 1 h group, hearing was improved after 1 day, and in the 5 h group, hearing was measured after 7 days. Changes in SDH activity were observed at the third day in the 1 h group and at the seventh day in the 5 h group. The expression level of MRC complex V was increased after noise exposure. TEM showed mitochondrial damage.Acta oto-laryngologica 06/2012; 132 Suppl 1:S134-41. · 0.98 Impact Factor -
Article: Early combination treatment with intratympanic steroid injection in severe to profound sudden sensorineural hearing loss improves speech discrimination performance.
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ABSTRACT: The objective of the study was to determine the therapeutic efficacy of early combined treatment with intratympanic steroid injection (ITSI) in patients with severe to profound sudden sensorineural hearing loss (SSNHL), who did not respond to initial systemic steroid treatment (SST). The study design included historical controlled trials (retrospective analysis for the SST group). Patients (n = 73; 38 women and 35 men) diagnosed with severe to profound SSNHL at the time of their first visit in tertiary referral centers were recruited. Among these 73 patients, 30 patients who showed no early response within a week after the start of initial SST were prospectively included as the ITSI group. ITSI was performed twice a week for two consecutive weeks. In contrast, 43 patients with the same condition who did not receive ITSI were retrospectively included as the SST group. For each group, pure-tone audiogram (PTA) and speech discrimination score (SDS) tests were performed before SST and more than 2 months after termination of treatment in each group. After termination of each treatment, the final average gain on PTA showed no significant difference between the two groups; however, the final average gain of SDS demonstrated a significantly better recovery in the ITSI group. ITSI as part of an early combined therapy represents an effective treatment in terms of the improvement of SDS in severe to profound SSNHL showing no early response to initial SST.Archives of Oto-Rhino-Laryngology 12/2011; 269(10):2173-8. · 1.29 Impact Factor -
Article: Cross-modal and compensatory plasticity in adult deafened cats: a longitudinal PET study.
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ABSTRACT: Although much is known about the cerebral neural plasticity that occurs after deafness, it is unclear how much time is required for its development or what other cortical changes may consequently occur. This study provides a longitudinal assessment of cerebral cortical neural plasticity, as manifested in adult deafened cats. A total of 5 male cats were subjected to whole cortex analysis of glucose metabolic activity via 2-deoxy-2[(18)F] fluoro-D-glucose (FDG) micro-positron emission tomography (PET). The imaging was performed at the baseline state of normal hearing and then at 4, 9, 24, and 33 months after the induction of deafness. We compared glucose metabolism between the normal hearing state and each deafened state by using voxel-based statistical analysis (P<0.005). Significant changes were observed in the primary auditory (A1) and primary visual (V1) cortices. A bilateral metabolic decrease was observed in A1 areas and in temporal auditory fields, the extent of which was significantly increased at Month 9. Then it was declined at Month 24. And finally it was disappeared by Month 33. Auditory cortical plasticity subsequent to deafness was thus demonstrated. Furthermore, a significant metabolic upsurge occurred in bilateral occipital areas at Month 33. This increase, involving bilateral occipital and thalamic areas of V1, suggests compensatory hyperactivity of the visual cortex after deafness.Brain research 10/2010; 1354:85-90. · 2.46 Impact Factor -
Article: Temporomandibular joint herniation into the external auditory canal.
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ABSTRACT: Herniation of the temporomandibular joint (TMJ) into the external auditory canal (EAC) is a very rare condition, and it mostly occurs in patients with bony wall defects in the anterior EAC. The purpose of this study was to evaluate the clinical and radiological findings and the treatment results of TMJ herniation into the EAC by reviewing a large sample of temporal bone computed tomography (CT) scans. A retrospective study. We reviewed 985 adult temporal bone CT scans and evaluated the presence of defects, the size and location of defects, and TMJ herniation. We enrolled 23 cases with anterior EAC wall defects. Twenty-three (2.3%) patients from the 985 temporal bone CT cases revealed an anterior wall defect involving the EAC. We identified the causes for the defects, such as canal cholesteatoma and trauma, in eight of the 23 cases. We observed 15 (1.5%) patients with patent foramen of Huschke. The mean defect size was 3.06 × 2.69 mm. Among the patients with these lesions, six had a TMJ herniation into the EAC. Four of the six cases were surgically reconstructed using a titanium mesh via a preauricular approach, whereas the remaining two cases were managed with endaural removal and skin graft. TMJ herniation into the EAC is very rare and may not occur even if an anterior wall defect of the EAC is present. Lesions can be successfully managed with surgical reconstruction of the TMJ via a preauricular approach, whereas small lesions can be managed using an endaural approach.The Laryngoscope 08/2010; 120(11):2284-8. · 1.75 Impact Factor
