Search PubMed⌕ Search

Biomedical subjects

S Komune

Publications and source records attributed to S Komune.

At least 37 records · Page 2Linked to original sources
PubMed1999

Recording of mechano-electrical transduction currents by a nystatin perforated-patch method.

Mechano-electrical transduction (MET) currents in isolated cochlear hair cells of chicks were recorded by use of a nystatin perforated-patch method. The membrane of a cell-attached patch was permeabilized by nystatin in the patch pipette, thus providing electrical continuity between the pipette and the cytoplasm of the cell without loss of cytoplasmic compounds. The current-voltage relationship was linear for the inward-going MET current at negative membrane potentials, but outward currents were reduced at positive membrane potentials, evidence of inward-going rectification. Elevation of the intracellular concentration of calcium at positive membrane potential, mediated via a voltage-dependent Ca2+ channel, may suppress the outward-going MET current by acting from within the cell.

Animals↗
PubMed1999

[Clinical experiences and postoperative results with partially implantable middle ear implant].

A partially implantable middle ear implant using an ossicular vibrator of a piezoelectric ceramic bimorph has recently been developed in Japan as a new rehabilitative method for hearing. Four patients at the Miyazaki Medical College Hospital were implanted with this device between September 1994 and October 1996. Implantation of the internal component was performed under local anesthesia after confirmation of sufficient sensitivity to the ossicular vibrator in an intraoperative vibratory hearing test. All patients regained socially useful hearing with the middle ear implant without any foreign body reactions or recurrence of otitis media. None of the cases showed any elevations of bone conduction thresholds 2 to 4 years postoperatively. Natural and clear sounds without interference noise and howling due to acoustic feedback were highly satisfactory in all patients. However, the first case, who had an implant in an ear following cholesteatoma surgery using the intact canal wall technique, experienced about a 10dB deterioration of the average hearing level with the implant 2 years after implantation. Gradual deterioration appeared to be caused by the retracted tympanic membrane interfering with the mobility of the ossicular vibrator. The following three cases were implanted in ears previously operated on by radical mastoidectomy, showing stable or improving hearing results with the implant. Closure of the external canal skin at the cartilaginous portion at the time of implantation seemed appropriate to maintain a sufficient middle ear space for the ossicular vibrator to work properly. Our case study confirms that the partially implantable middle ear implant is a safe and useful tool for patients with mixed deafness which cannot be satisfactorily rehabilitated by tympanoplasty and/or a conventional hearing aid.

Deafness↗
PubMed1998

High potassium-induced glutamate release in the cochlea: in vivo microdialysis study combined with on-line enzyme fluorometric detection of glutamate.

The time course of changes in perilymphatic glutamate release and their Ca2+-dependency were studied in the guinea pig cochlea during high K+-evoked depolarization. The glutamate concentration was analyzed continuously by an enzyme-linked fluorometric assay combined with microdialysis. Two peaks of glutamate increase were found in response to perfusion for 10 min. In the absence of Ca2+, the first peak was diminished, whereas the inhibition of the second peak was minimal.

Animals↗
PubMed1998

Elevation of intracellular calcium induced by the intrapipette perfusion technique modifies membrane ion currents in the chick cochlear hair cell.

The concentration of intracellular calcium ion ([Ca2+]i) was altered in the same hair cell dissociated from a chick cochlea by the intrapipette perfusion technique. At a membrane potential of -40 mV, the elevation of [Ca2+]i generated outward-going currents within 60 sec when the intrapipette solution was based on KCl. In controls, at membrane potentials more positive than -50 mV, outward K+ currents were observed and at large positive potentials, the outward K+ current decreased, showing an N-shaped I-V relationship. This outward K+ current was increased by elevation of [Ca2+]i and was partially suppressed by a TEA-containing extracellular solution. We suggest that the Ca2+ increased by the intrapipette perfusion technique operates directly inside the cell membrane and activates Ca(2+)-activated K+ currents.

Animals↗
PubMed1998

Changes of perilymphatic glutamate and cochlear blood flow following ischemia.

Dynamic changes of perilymphatic glutamate and cochlear blood flow were measured simultaneously in the guinea pig following cochlear ischemia. Glutamate was measured by the microdialysis technique with a probe inserted into the scala tympani at the basal turn. Cochlear blood flow was monitored with a laser-Doppler probe on the lateral wall of the second cochlear turn. Both parameters were measured before and after electrocauterization of the anterior inferior cerebellar artery and other vessels supplying the internal auditory canal. In four animals, glutamate increased with a decline of cochlear blood flow and then decreased with recovery of blood flow. No normalization of glutamate was observed in seven animals with a persistent decrease of blood flow. The results of this study indicate that the glutamate regulating system in the cochlea is dependent on cochlear blood flow.

Animals↗
PubMed1998

Effects of trimetaphan-induced deliberate hypotension on human cochlear blood flow.

In order to observe the reaction of cochlear blood flow (CBF) to trimetaphan (TMP)-induced hypotension, CBF was measured with laser-Doppler flowmetry in 7 human subjects during general anaesthesia for middle ear surgery. All subjects showed a decrease in mean arterial pressure (MAP) during intravenous infusion of TMP, followed by a gradual return to the baseline level after termination of the infusion. The CBF generally followed the MAP changes with the same pattern. Three of the seven subjects demonstrated a CBF change larger than the maximum MAP change, indicating the lack of a local autoregulatory mechanism in CBF. On the other hand, CBF changes were smaller in magnitude than the maximum change in MAP for the rest of the subjects, suggesting an autoregulatory mechanism in CBF. However, since the audiograms from these subjects indicated profound damage along the cochlear basal turn probably due to middle ear inflammation, concomitant vascular damage in this region offers another possible explanation for the inappropriate CBF changes. The present observations may also suggest that deliberately TMP-induced hypotension has a potentially harmful effect on CBF during otological surgery that attempts to preserve or improve hearing.

Adult↗
PubMed1998

Cochlear implantation in a patient with profound hearing loss with the A1555G mitochondrial mutation.

OBJECTIVE: This study aimed to describe the performance of a cochlear implant in a patient with profound hearing loss with the A1555G mitochondrial mutation. SETTING: The study was conducted at two university hospitals. PATIENT: A 50-year-old Japanese man in whom bilateral profound hearing loss developed after administration of streptomycin at the age of 23 participated. The pedigree of the family showed exclusively maternal transmission of hearing impairment. INTERVENTION: Genetic study and auditory rehabilitation with a cochlear implant were performed. RESULTS: The A1555G point mutation was identified from the patient's mitochondrial DNA. Since activation of the implant, the patient has been using it successfully with a monosyllable recognition score of 78% using Japanese word lists for speech audiometry. CONCLUSIONS: The current case indicated that cochlear implantation may be a valuable choice of therapy for the patient with profound hearing loss with the A1555G mutation. The excellent auditory performance with a cochlear implant suggests that hearing loss associated with this mutation is primarily caused by insult to the cochlear tissue containing rich mitochondria (i.e., hair cells or stria vascularis or both), not to the cochlear nerve and its central connections.

Antibiotics, Antitubercular↗
PubMed1996

Gadolinium blocks mechano-electric transducer current in chick cochlear hair cells.

We investigated the effects of gadolinium ion (Gd3+) on the mechano-electrical transduction (MET) current using a whole-cell patch electrode voltage clamp technique in dissociated cochlear hair cells of chicks. Gd3+ blocked the MET channel in a concentration- and voltage-dependent manner. At -50 mV, Gd3+ blocked the MET channel, with a Hill coefficient of 1.14 and a dissociation constant (KD) of 1.01 x 10(-5) M. Adaptation of the MET current disappeared after the introduction of Gd3+, a change that may be due to a decrease in inward going MET currents, specifically the Ca2+ component.

Animals↗
PubMed1996

[Sudden sensorineural hearing loss associated with anticardiolipin antibody].

We experienced three female patients with sudden sensorineural hearing loss. All the patients showed elevation of anticardiolipin antibody in the serum. Immunoglobulin (Ig) M anticardiolipin antibody was present in case 1 (a 34-year old woman). IgG anticardiolipin antibodies were present in cases 2 (a 50-year-old woman) and 3 (a 9 year old girl). The patient in case 1 showed hearing disturbance of low tone in the left ear and normal vestibular function in both ears. The case 2 patient had an average hearing level of 81.7dB at 0.5. 1, and 2kHz and severe canal paresis in the right ear. In case 3 the patient showed an average hearing level of 53.3dB in the right ear and normal vestibular function in both ears. It was suggested that thrombosis which might have been induced by anticardiolipin antibody could have caused the sudden sensorineural hearing loss in these patients. Steroid therapy cured the hearing disturbance completely in case 1. Steroid and prostaglandin E1 therapy did not improve the hearing disturbance in case 2. Steroid, prostaglandin E1, and ticlopidine hydrochloride therapy improved the hearing disturbance in case 3. It appears that not only steroids but also prostaglandin E1 and ticlopidine hydrochloride therapy may be effective in patients with sensorineural hearing loss associated with anticardiolipin antibody.

Acute Disease↗
PubMed1995

Measurement of intracellular free Ca2+ concentration in guinea pig spiral ganglion cells.

Intracellular free Ca2+ concentration ([Ca2+]i) in spiral ganglion cells (SGC) of guinea pig was measured using the fura-2 fluorescence method. Application of high-K+ external solution increased [Ca2+]i. [Ca2+]i elevation was suppressed by either depletion of external Ca2+ or application of the dihydropyridine Ca2+ channel antagonist, nicardipine. One of the putative hair cell afferent nerve neurotransmitters, L-glutamate (Glu), induced [Ca2+]i elevation in SGC. Pharmacological studies suggested that the Glu receptor may be a non-NMDA subtype. Glu-induced response was suppressed by either depletion of external Ca2+ or application of nicardipine, indicating that Glu-induced [Ca2+]i elevation is mainly carried out by the voltage-dependent Ca2+ channel in SGC.

Animals↗
PubMed1995

Voltage-dependent Ca2+ channels in the spiral ganglion cells of guinea pig cochlea.

Voltage-dependent Ca2+ channels in spiral ganglion cells (SGCs) isolated from guinea pig cochlea were investigated using the patch-clamp technique in a whole-cell recording mode. The voltage-dependent Na+ and K+ currents were blocked by adding tetrodotoxin, 4-aminopyridine, and tetraethylammonium to the external solution and by using choline or Cs+ in the external and internal solutions instead of Na+ or K+, respectively. The depolarizing voltage steps evoked inward currents with slow current decay. The maximum amplitude of the inward current increased in a hyperbolic manner with increasing extracellular Ca2+ concentration, indicating that the inward current was a voltage-dependent Ca2+ current (ICa). In 5 mM Ca2+ external solution, the ICa activated from a membrane potential around -60 mV and reached full activation at about -10 mV. The ICa inactivated from about -60 mV and became fully inactivated at about O mV, consistent with the high-voltage-activated Ca2+ channel subtype. Ionic selectivities for Ca2+ channels in SGCs were as follows: Ca2+ > Ba2+ > Sr2+. Effects of both inorganic and organic Ca2+ antagonists also were examined. The inhibitory strength was as follows: La3+ > Cd2+ > Ni2+ > or = Co2+ for inorganic Ca2+ antagonists, and flunarizine > nicardipine > methoxyverapamil > diltiazem for organic ones.

4-Aminopyridine↗
PubMed1995

Case report: the first report of idiopathic hypereosinophilic syndrome involved with lung and middle ear.

It has been reported that various organs are involved in idiopathic hypereosinophilic syndrome. Frequently, the heart, lung, skin, and nervous system are involved. Involvement of the middle ear, however, has not yet been reported. In this article, the authors describe the first case of hypereosinophilic syndrome involving the lung and middle ear. A 39-year-old woman had a 4-month history of low grade fever, non-productive cough, and a feeling of fullness and hearing loss in both ears. Peripheral blood cell count showed eosinophilia. Bilateral tympanic cavities were obstructed with granulation tissue, and she was diagnosed as obliterative otitis media. The granulation tissue consisted of foamy histiocytes and eosinophils. Chest X-ray film and computed tomography showed patchy infiltrative shadow in the lung. Histologic examination of the open lung biopsied specimen showed alveolar spaces infiltrated by eosinophils. After treatment with 30 mg oral prednisolone daily, there was a rapid improvement in her clinical condition. Based on the clinical course and the histologic findings of this case, obliterative otitis media may be caused by eosinophilic infiltration and eosinophilic pneumonia.

Adult↗
PubMed1995

Disturbance of regulation of sodium by cis-diamminedichloroplatinum in perilymph of the guinea pig cochlea.

We studied the acute effects of cis-diamminedichloroplatinum (CDDP) on the cochlear partition and inner ear fluid in the guinea pig. At 48 hours after the administration of a single intramuscular injection of CDDP, 12.5 mg/kg of body weight, the endocochlear resting potential (EP) was significantly decreased to 32.1 +/- 1.8 mV in the treated animals, versus 80.6 +/- 1.0 mV in the control animals. There was a significant rise in potassium (K+), sodium (Na+), and chlorine (Cl-) in the endolymph of the animals treated with CDDP as compared with the control animals. Only Na+ was found to increase significantly in the perilymph, reaching more than twice the level of the control animals; both K+ and Cl- remained within the normal range. Serum electrolytes also remained within the normal range. Evaluation of modified ionic permeabilities across the endolymph-perilymph barrier showed an apparent increase in Na+ permeability and a normal range of K+ and Cl- permeabilities. Histopathologic examination of the cochlea showed a moderate collapse of the endolymphatic space, with atrophy of the stria vascularis and destruction of the outer hair cells. The findings suggest that the acute changes produced in the cochlea by administration of CDDP were attributable to a breakdown in the regulation of Na+ metabolism in the perilymph.

Animals↗
PubMed1995

[Steroid-responsive sensorineural hearing loss with low tone loss].

Five cases of sensorineural hearing loss of sudden onset were reviewed. They were not responsive to administration of ATP and Vit. B12, but very responsive to steroid administration. All the patients were male and showed hearing loss in low frequencies in pure tone audiogram. Administration of steroid recovered hearing impairment immediately. However, cessation of steroid aggravated the recovered hearing. Serological and immunological examinations did not show any abnormal findings on all the patients. It was considered that these five patients had characteristics of both steroid-sensitive and low tone-loss type sensorineural hearing losses.

Administration, Oral↗
PubMed1994

Ionic properties of IK,n in outer hair cells of guinea pig cochlea.

The ionic properties of voltage-dependent K+ current activated at the resting membrane potential (IK,n) of outer hair cells (OHC) isolated from the guinea pig cochlea were studied using a patch-clamp technique in a whole-cell recording mode. The reversal potential of IK,n indicated a high selectivity for K+, and the relative permeability ratios for various monovalent cations were K+:Rb+:NH4+ = 1:1.21:0.13. Decrease in extracellular Cl- inhibited the IK,n. IK,n was blocked by Cs+ and Ba2+, although the inhibitory manner of Cs+ and Ba2+ were voltage-dependent and voltage-independent, respectively. By the use of puff-application method, the local application of Ba2+ to basolateral surface of OHC shifted the holding current level in an inward direction, whereas the application to apex and hair showed little change. Indicating that the IK,n channels preferentially locate at the basolateral region of cell membrane.

Ammonia↗
PubMed1994

A 16-year survey of changes in bacterial isolates associated with chronic suppurative otitis media.

Bacteria were isolated and cultured from the ears of outpatients with chronic suppurative otitis media (OMC) who attended the otologic clinics of Kyushu University Hospital from 1976 to 1991. Bacterial isolates were analyzed retrospectively to determine their incidences and antibiotic sensitivities. Staphylococcus aureus and Pseudomonas aeruginosa were the most commonly isolated organisms. The incidence of S. aureus infections gradually rose over 16 years, while the incidence of Proteus infections gradually declined. The frequency of isolation of glucose non-fermenting gram-negative rod (NF-GNR) species, fungi and anaerobic bacteria gradually increased. The species of bacteria isolated from OMC cases with acute and chronic infections, cholesteatoma and postoperative infections were compared. Over the 16 years, the isolation of S. aureus increased in frequency. The differences in each type of OMC ceased to exist. S. aureus were quite sensitive to most of the antibiotics tested, whereas Ps. aeruginosa and NF-GNR showed poor sensitivity.

Acute Disease↗