Yasuyuki Hashimoto

A model of two-stage newborn hearing screening with automated auditory brainstem response.

Our purpose was to evaluate a two-stage newborn hearing screening program using automated auditory brainstem response (AABR) before discharge and to describe our follow-up program. This study used 4085 infants born in the Seirei-Hamamatsu and Mikatahara General Hospitals during a 2-year period. The initial screening test was performed 2 or 3 days after birth at an intensity of 35 dBnHL. For the infants who were referred from this test, the re-screening test was performed 5 or 6 days after birth. Diagnostic work-up with auditory brainstem response (ABR), otoacoustic emissions (OAE), and a conditioned orientation reflex audiometry (COR) test were performed by the age of 3-6 months. The referral rate was 1.20% (49/4085 infants) in the first test and 0.71% (29/4085 infants) in the two-stage screening. The two-stage screening procedure was able to reduce the false-positive rate from 0.83 to 0.34%. The incidence of bilateral and unilateral congenital hearing loss diagnosed by ABR was 8/4085 (0.20%) infants and 7/4085 (0.17%) infants, respectively. One infant with congenital cytomegalovirus infection, who passed the two-stage AABR tests, was diagnosed with hearing loss 1 month after birth, using ABR. The two-stage measurement of AABR is effective and time efficient due to significant decreases in the referral rate and the false-positive rate.

Ultrastructural co-localization of cochlin and type II collagen in the rat semicircular canal.

Cochlin and type II collagen are major constituents of the inner ear extracellular matrix. To investigate the morphological relation of cochlin and type II collagen in the rat semicircular canal, immuno-electronmicroscopic analysis was performed using the post-embedding immunogold method. Immunolabeling for cochlin was detected in the fibrillar substance underlying the supporting epithelium of the sensory cells and beneath the epithelial cells facing the endolymph in the semicircular canals. Immunolabeling for type II collagen was observed in the same fibrillar substance in the subepithelial area. The co-localization of cochlin and type II collagen in the fibrillar substance in the subepithelial area indicate that cochlin may play a role in the structural homeostasis of the vestibule acting in concert with the fibrillar type II collagen bundles.

Pattern of cochlear damage caused by short-term kanamycin application using the round window microcatheter method

Conclusion. Short-term local application of kanamycin by the microcatheter method can control the region and severity of drug effect on the cochlea by changing the concentration and administration time. Objectives. To investigate the effect of short-term round window administration of kanamycin by the microcatheter method on cochlear stereociliary bundle loss in a guinea pig model. Materials and methods. Two concentrations and two time periods were used for drug administration to the inner ear. In groups of six animals, a total dose of 172.5 mg/ml or 345 mg/ml of kanamycin was instilled at the rate of 0.1 ml/h into the round window niche over either a 1 h or 2 h period by the microcatheter method. One group of six animals received a saline infusion as a control. The animals were sacrificed after 4 days and stereociliary bundle loss was observed by SEM. Functional changes were evaluated by auditory brainstem response. Results. With regard to the severity of the damage, higher drug concentrations were associated with more severe effects. The severity of damage was the same when the same total dose was used; however, it was found that when the dose was administered over a longer period, the damage region was wider. The functional changes also corresponded with the morphological changes.

Localization of megalin in rat vestibular dark cells and endolymphatic sac epithelial cells.

Conclusion: Megalin immunoreactivity was observed in kidney proximal tubule cells, vestibular dark cells, and epithelial cells of the endolymphatic sac. Endocytic mechanisms appear to differ between the endolymphatic sac and proximal tubule cells. We speculate that megalin is secreted by a certain type of cell into the endolymphatic space, and is then absorbed from the endolymphatic space by another type of cell to maintain endolymphatic sac homeostasis. Objectives: We previously detected megalin immunoreactivity in the rat cochlear duct. Megalin may be involved in endocytosis in the vestibular organ and endolymphatic sac. To examine this possibility, we extended our immunocytochemical investigation to the rat inner ear cells with special attention to vestibular dark cells and endolymphatic sac. Materials and methods: We observed immunoreactivity of megalin under light and electron microscopy. The primary antibody was rabbit polyclonal antibody that had been raised against rat immunoaffinity-purified megalin. Results: The luminal membrane and subapical area of dark cells in the semicircular canal were immunolabeled. The stainable substance in the endolymphatic space was strongly stained. The cytoplasm of epithelial cells was also stained in various patterns.

Ultrastructural Localization of Cochlin in the Rat Cochlear Duct

Cochlin, a product of the COCH gene, is a major constituent of the inner ear extracellular matrix. Type II collagen, a protein that contributes to structural stability, is also a component of this extracellular matrix. In this study, using the postembedding immunogold method, we demonstrate the localization of cochlin and type II collagen in the cochlear duct at the ultrastructural level. The immunolabeling of cochlin was observed in the fibrillar substance in the spiral limbus, beneath the inner sulcus cells, and in the basilar membrane, the spiral prominence and the spiral ligament. Immunolabeling of type II collagen was observed in the same fibrillar substance in the extracellular matrix of the cochlear duct. This localization of cochlin is consistent with the expected localization of type II collagen. The localization of cochlin and type II collagen indicates the important roles played by these proteins in the hearing process.

Efficacy of Onon (pranlukast hydrate) for theImprovement of Quality of Life in Patients with Allergic Rhinitis

The aim of this study was to evaluate the effects of novel leukotriene antagonist, pranlukast hydrate on improvement of quality of life (QOL) as well as reduction of clinical symptoms in patients with allergic rhinitis.Fifty patients with perennial and/or seasonal allergic rhinitis were administered 450mg pranlukast hydrate daily for at least 4 weeks. The severity of clinical symptoms and QOL were assessed before and after treatment.After a 4-week period of treatment, the QOL score significantly improved from 2.1±1.5 to 1.2±1.7 (P<0.0001). In addition, the treatment itself did not affect the QOL of the patients. The severity of symptoms was also significantly reduced (P<0.001). The improvement rates were 66.0% (sneezing), 72.0% (rhinorrea), and 82.0% (nasal obstruction).In conclusion, pranlukast hydrate improves QOL and reduces symptoms in patients with allergic rhinitis.

Long-term audiological feature in pendred syndrome caused by SLC26A4 mutation

Abstract Objectives: Pendred syndrome is inherited as an autosomal recessive form and may account for 10% of hereditary hearing loss. It is likely that there is a great variation in hearing loss. We report a case of Pendred syndrome in which a mutation in SLC26A4 gene was detected and show the characteristics of long-term audiological changes. Methods: A 27-year-old woman was followed since March 1979 at Hamamatsu University School of Medicine. She first experienced vertigo at the age of 1 1/2 years and her parents were concerned about her poor response to sound. Mild hearing loss was diagnosed in another clinic at the age of 4 years. Results: Long-term audiological observation over 20 years showed that a 45 dB in the right ear and 41.2 dB in the left ear increased as the average threshold with fluctuation and marked progression combined with vertigo occurred before the age of 12. After that, the threshold moved to the stable. The audiogram indicated an asymmetric pattern and sensorineural hearing loss predominantly. A caloric test revealed a normal response on both sides. Corticosteroids were not effective in improving hearing loss. A diffuse goiter was noticed at the age of 15 years. The goiter slightly enlarged over the 12 years follow-up period. Conclusion: Although the His723Arg missense mutation is a change at unconserved position in the pendrin protein, it is a pathological mutation in our case because it was found in the homozygous state. It is possible that different mutations within the same gene lead to different phenotypes.

A model of two-stage newborn hearing screening with automated auditory brainstem response

Our purpose was to evaluate a two-stage newborn hearing screening program using automated auditory brainstem response (AABR) before discharge and to describe our follow-up program. This study used 4085 infants born in the Seirei-Hamamatsu and Mikatahara General Hospitals during a 2-year period. The initial screening test was performed 2 or 3 days after birth at an intensity of 35 dBnHL. For the infants who were referred from this test, the re-screening test was performed 5 or 6 days after birth. Diagnostic work-up with auditory brainstem response (ABR), otoacoustic emissions (OAE), and a conditioned orientation reflex audiometry (COR) test were performed by the age of 3-6 months. The referral rate was 1.20% (49/4085 infants) in the first test and 0.71% (29/4085 infants) in the two-stage screening. The two-stage screening procedure was able to reduce the false-positive rate from 0.83 to 0.34%. The incidence of bilateral and unilateral congenital hearing loss diagnosed by ABR was 8/4085 (0.20%) infants and 7/4085 (0.17%) infants, respectively. One infant with congenital cytomegalovirus infection, who passed the two-stage AABR tests, was diagnosed with hearing loss 1 month after birth, using ABR. The two-stage measurement of AABR is effective and time efficient due to significant decreases in the referral rate and the false-positive rate.