Masao Yagi

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Glial cell line-derived neurotrophic factor (GDNF) overexpression in the inner ear can protect hair cells against degeneration induced by aminoglycoside ototoxicity. The protective efficiency of GDNF increases when it is combined with co-factors such as transforming growth factor beta1 (TGF-beta1), a ubiquitous cytokine. The aim of this study was to(More)
This study demonstrates the attenuation of aminoglycoside ototoxicity by cochlear infusion of dexamethasone (Dex) using a microcannulation-osmotic pump delivery system. The results indicate that treating the cochlea with Dex both before and after kanamycin administration was more effective in preventing ototoxicity than Dex treatment only after kanamycin(More)
The protective effect of dexamethasone (DEX) against noise-induced trauma, as reflected in hair cell destruction and elevation in auditory brainstem response (ABR) sensitivity, was assessed in guinea pigs. The animals were administered DEX (1, 10, 100, and 1000 ng/ml) or artificial perilymph (AP) via a mini-osmotic pump directly into scala tympani and, on(More)
Brief cochlear excitotoxicity produces temporary neural swelling and transient deficits in auditory sensitivity; however, the consequences of long-lasting excitotoxic insult have not been tested. Chronic intra-cochlear infusion of the glutamate agonist AMPA (a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) resulted in functional deficits in the(More)
Antidepressant treatments have been described to induce neurotrophic factors (NTFs) and reverse the cell loss observed in rodent stress models. Amitriptyline (AT), a tricyclic antidepressant agent, has been reported in recent studies to induce glial cell line-derived neurotrophic factor (GDNF) synthesis and release in rat C6 glioblastoma cells. GDNF has(More)
The histological characteristics of the vestibule in a strain of new-mutant mice were studied under light microscopy. These new-mutant mice, manifesting drawing back, circling, head-tossing and hyperactive behavior arose as a spontaneous mutation in the C3H/He stock. For our study, 36 of these mice ranging in age from 10 days to 18 months were used. At 10(More)
The hearing ability and histological characteristics of the cochlea of a strain of new-mutant mice were analyzed. This new mutant arose as a spontaneous mutation in the C3H/He stock. The genetic mode is autosomal recessive and the animals show abnormal behavior such as circling, head-tossing and hyperactivity. The audiological findings exhibited no(More)
CONCLUSION We characterized side population (SP) cells in the cochlear nucleus (CN). Some genes of stem/progenitor markers in sorted SP cells were identified by microarray analysis and RT-PCR. Furthermore, some cells in the CN also demonstrated self-renewal and clonal expansion activities. These results suggest that tissue stem/ progenitor like cells would(More)