Biomedical subjects

K Hisashi

Publications and source records attributed to K Hisashi.

4 recordsLinked to original sources

PubMed1992

Interlay method for myringoplasty.

Sixty-nine ears with perforation of the tympanic membrane were reviewed. All had undergone myringoplasty by the interlay method. The average period for complete epithelization was 16.1 days after surgery. Neither blunting of the anterior tympanomeatal angle nor lateralization of the tympanic membrane was observed. The success rate was 94.2% for the initial surgery, when "success" is defined as closure of the perforation and complete epithelization (dry ear). The surgical technique and various advantages of the interlay method of myringoplasty are described.

Adolescent↗

PubMed1992

Importance of atticotomy in chronic otitis media with fixation of ossicles.

Seventy-seven patients with chronic otitis media were reviewed. Of the 77 patients, 42 underwent tympanoplasty with a columella, and 35 underwent myringoplasty and atticotomy. Twenty-five of the latter 35 patients showed less than 10 dB of hearing improvement with a patch test before operation. The ossicular chain was not disconnected in any of the 25 patients, but the mobility was severely restricted. It was interesting that fixation of the malleus was found at surgery in 80% (20/25) of the patients, whereas the stapes was immobilized in only 16% (4/25). Myringoplasty and atticotomy instead of tympanoplasty with a columella was sufficient to achieve hearing improvement in most of such cases. However, conventional atticotomy was not able to achieve improvement in the mobility of the ossicles because the mobility is usually severely restricted at the malleus. Removal of the anterior tympanic spine is the key to recovery of the mobility of the malleus, resulting in hearing improvement. Rate of success was obtained in 24 of 25 ears (96%).

Auditory Threshold↗

PubMed1991

Ototoxic effect of potassium canrenoate on the guinea pig cochlea.

Potassium canrenoate (PC) is a diuretic with antialdosterone action, reducing the reabsorption of sodium in the efferent renal tubules. This drug has been reported to damage only the marginal cells of the stria vascularis in the cochlea. The perilymphatic space of the guinea pig cochlea was perfused with an artificial perilymph containing 5 x 10(-3) M potassium canrenoate. Following the onset of perfusion, the endocochlear dc potential (EP) gradually declined to around 10 mV but did not become negative even when the perfusion was continued. A similar decrease in EP was observed in kanamycin-deafened guinea pigs. When the respirator was turned off and perfusion discontinued, a large negative EP appeared during 5 min of anoxia in normal guinea pigs but not in the kanamycin-deafened guinea pigs. The decreased EP recovered to preanoxic level after resumption of ventilation. The cochlear microphonics (CM) also gradually declined in parallel with the EP. The summating potential (SP) showed only a minor change. The potassium ion activity in the endolymph decreased slightly but the sodium ion activity remained unchanged during perfusion. These findings suggest that the main target of the PC is the cells of the stria vascularis.

Animals↗

PubMed1990

[Effect of potassium canrenoate on the EP and Na+, K+ activities in endolymph].

The perilymphatic space was perfused with artificial perilymph containing 5 x 10(-3)M potassium canrenoate. The EP, K+ and Na+ activities in the scala media were measured with double barrelled K+ or Na+ selective microelectrode. Following the onset of the perfusion, the EP gradually declined and was stable after about 20 minutes. K+ activity also declined gradually but Na+ activity was unchanged. When the EP became stable, the artificial ventilation was stopped. The EP dropped to a large negative potential and K+ activity decreased gradually, but Na+ activity increased by degrees. The same results were observed in the untreated animals when the ventilation was stopped. There are no pathological changes both in the TEM view of the stria vascularis and in the SEM view of the hair cell. These results suggest that this drug may affect K+ conductance of the stria vascularis specifically.

Animals↗