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Biomedical subjects

S Komune

Publications and source records attributed to S Komune.

9 recordsLinked to original sources
PubMed1992

Effects of Ca2+ antagonists and aminoglycoside antibiotics on Ca2+ current in isolated outer hair cells of guinea pig cochlea.

The effects of various Ca2+ antagonists and aminoglycoside antibiotics on the Ca2+ channel in isolated outer hair cells of the guinea pig were investigated using a whole-cell patch-clamp technique. The inhibitory action was in the order of La3+ much greater than Cd2+ much greater than Ni2+ greater than Co2+ for inorganic Ca2+ antagonists, and flunarizine = nicardipine greater than omega-conotoxin greater than methoxyverapamil = diltiazem much greater than amiloride for organic ones. Aminoglycoside antibiotics also had antagonistic effects on the Ca2+ channel.

Aminoglycosides↗
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

Calcium channel in isolated outer hair cells of guinea pig cochlea.

The physiological and pharmacological properties of the Ca2+ channel in outer hair cells (OHCs) freshly isolated from guinea pig cochlea were investigated using a whole-cell patch-clamp technique. The Ca2+ current (ICa) was activated from a membrane potential of -20 mV and reached peak value around +20 mV in external solution containing 20 mM Ca2+ at a holding potential of -70 mV. The peak amplitude of ICa increased in a hyperbolic manner with increasing extracellular Ca2+ concentration. The ion selectively was Ba2+ much greater than Ca2+ greater than or equal to Sr2+. It was concluded that the Ca2+ channel in OHCs of guinea pig is of the L-type.

Action Potentials↗
PubMed1991

Excitatory amino acid response in isolated spiral ganglion cells of guinea pig cochlea.

1. The physiological and pharmacological properties of excitatory amino acid (EAA)-induced responses were investigated in acutely isolated spiral ganglion cells of guinea pig by a conventional patch-clamp technique combined with a rapid drug application (Y-tube) method. 2. L-glutamate (Glu) and its agonists, quisqualate (QA) and kainate (KA), induced inward currents in a concentration-dependent manner at a holding potential (VH) of -70 mV. The values of half-maximal concentration (EC50) were 4.0 x 10(-4) M for Glu, 2.3 x 10(-5) M for QA, and 1.4 x 10(-4) for KA. The Hill coefficients were 0.96, 1.00, and 1.56 for Glu, QA, and KA, respectively. However, one of Glu agonists, N-methyl-D-aspartate (NMDA), and another excitatory amino acid, L-aspartate (Asp), did not induce any responses even in Mg2(+)-free external solution containing 10(-6) M glycine (Gly). 3. The current-voltage (I-V) relationships for the Glu-, QA-, and KA-induced responses were linear, and these reversal potentials were near 5 mV. 4. Kynurenic acid (Kyn), 6,7-dichloro-3-hydroxy-2-quinoxalinecarboxylic acid (diCl-HQC), and quinoxalinediones such as 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 6,7-dinitro-quinoxaline-2,3-dione (DNQX) suppressed the Glu-, QA-, and KA-induced currents in a concentration-dependent manner. The inhibitory potency was in the order of DNQX = CNQX greater than diCl-HQC greater than Kyn. 5. CNQX antagonized the Glu-, QA-, and KA-induced currents without affecting the maximum responses showing no voltage-dependency, indicating the competitive inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
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↗
PubMed1991

[Neuro-otological study of Laurence-Moon-Biedl syndrome].

Two siblings of Laurence-Moon-Biedl (L-M-B) syndrome with nystagmus and/or sensorineural hearing loss were reported. One sibling had a slight hearing impairment as well as gaze and rebound nystagmus. The auditory brainstem responses (ABR) showed increased latencies of wave V on both ears. The optokinetic nystagmus (OKN) was limited toward the both horizontal sides. Nystagmus was superimposed on the eye tracking movement. Ocular hypermetria was observed, with bilateral weakness of caloric responses and even a failure of visual fixation suppression. Another sibling had a left-beating spontaneous nystagmus. The latencies of wave V of ABR were prolonged in both ears. The leftward OKN was limited and bilateral saccadic pursuits observed on eye tracking test. These results suggest that cerebellar of brain-stem lesions may be involved in L-M-B syndrome.

Adult↗