Biomedical subjects

Masafumi Taniguchi

Publications and source records attributed to Masafumi Taniguchi.

3 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

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↗

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↗