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Biomedical subjects

S Komune

Publications and source records attributed to S Komune.

At least 73 records · Page 4Linked to original sources
PubMed1987

Effects of kanamycin sulfate on cochlear potentials and potassium ion permeability through the cochlear partitions.

The cochlear microphonics (CM), endocochlear potential (EP) and potassium ion activities in the endolymph and perilymph were measured in guinea pigs which received daily successive intramuscular injections of 500 mg/kg of body weight of kanamycin sulfate. Preyer's reflex threshold at 8 kHz began to increase after the 5th day of kanamycin treatment and disappeared on the 11th day. The maximum output of CM at 8 kHz began to decrease with a time course similar to Preyer's reflex. The potassium ion activities in the endolymph and perilymph and the EP did not change appreciably through all experimental days. The magnitude of the negative EP decreased in parallel with the reduction in CM and the relative potassium conductance (GK) between the endolymph and perilymph. These results lend support to the hypothesis that the site of production of the negative EP is probably in the hair cells and that the negative EP is mainly dependent on the permeability of the potassium ions in the organ of Corti.

Animals↗
PubMed1986

Recurrent meningitis due to spontaneous cerebrospinal fluid otorrhea. A case report.

Bilateral congenital deafness was observed in a 9-year-old girl with recurrent meningitis. A careful workup, including polytomograph, CT scanning and Radioisotope (RI)-cisternography revealed an inner ear dysplasia of the Mondini type, viz. dilation of the lateral semicircular canal, vestibule and cystic degeneration of cochlea on both ears. RI-cisternography demonstrated an abnormal accumulation of radioisotope in the left mastoid region, suggesting spontaneous cerebrospinal fluid (CSF) otorrhea. At exploratory tympanotomy of the left ear, the CSF leak was found from a round defect in the center of the stapedial foot plate. The CSF leak was treated successfully by packing the vestibule with temporal fascia. Spontaneous CSF otorrhea is seldom the cause of meningitis but has to be considered especially if associated with a dead ear and with recurrent meningitis. The diagnosis and management are discussed.

Cerebrospinal Fluid Otorrhea↗
PubMed1986

Two cases of intratemporal facial nerve neurilemmomas.

The patients with neurilemmomas of the facial nerve within the temporal bone were treated. Although most of cases of the facial nerve neurilemmoma in the temporal bone present with a facial palsy, a few cases have normal facial nerve function and are especially difficult to diagnose preoperatively because of few symptoms. Case 1, a 31-year-old man, developed progressive left facial palsy with protrusion of the posterior wall of the external auditory meatus over a five-month period. Case 2, a 64-year-old man, complained of only fullness and tinnitus of the right ear without any facial nerve symptoms. Polytomography of the temporal bone demonstrated no abnormal findings in both cases. However, computed tomography revealed a soft-tissue density area in the left mastoid cavity with destruction of the posterior wall of the external auditory meatus in case 1. A similar soft-tissue density mass was found in the right tympanic cavity in case 2, suggesting the presence of the tumor in the temporal bone. At operation, the tumors were found to originate from the vertical portion of the facial nerve in both cases. It was assumed that normally existing dehiscences of fallopian canal might account for why some patients have normal facial nerve function.

Adult↗
PubMed1985

Dissociation of the cochlear microphonics and endocochlear potential after injection of ethacrynic acid.

The cochlear microphonics (CM), endocochlear potential (EP) and summating potential (SP) were simultaneously recorded for 60 min after injection of 30 mg/kg body weight of ethacrynic acid. The EP decreased parallel with the CM for about 20 min after injection, but they differed in the recovery stage. Even when the EP was still negative, the output of CM for 500 Hz acoustic stimulus recovered to its original level and was supernormal. A large SP observed in the recovery stage of CM and EP seemed to suggest that some functional change in the hair cells might be connected with the supernormal CM. Four minutes of anoxia during the supernormal CM decreased CM to only 68% of its level prior to anoxia. A cathodal polarization of the scala media, to change the polarity of the dc potential gradient, reversed the polarity of CM in the anoxic guinea-pig cochlea but not in the guinea-pig cochlea administered ethacrynic acid. These results suggest that supernormal CM observed in this experiment may not be dependent on the dc potential gradient, but due to some functional change in the hair cells after the injection of ethacrynic acid, although CM is essentially dependent on the dc potential gradient between the scala media and the inside of the hair cells.

Acoustic Stimulation↗
PubMed1985

A possible site of production of the negative endocochlear DC potential.

The scala vestibuli or the scala tympani of guinea pigs was perfused with artificial perilymph containing 1, 5, 10, 20, 30, 40 and 50 mM of potassium chloride in a total concentration of 150 mM with the background composed of sodium chloride. With the perfusion of the scala vestibuli, each concentration failed to alter the magnitude of the negative endocochlear DC potential produced by anoxia or the intravenous injection of 100 mg/kg of body weight of furosemide. With the perfusion of the scala tympani, the negative endocochlear DC potential disappeared precipitously and the maximum output of the cochlear microphonic was severely depressed with concentrations of potassium chloride of 30 mM or greater. The magnitude of the negative endocochlear DC potential appears to be closely related to the maximum output of the cochlear microphonic. These results suggest that the site of production of the negative EP is in the hair cells of the organ of Corti.

Animals↗
PubMed1983

Mechanism of the production of the negative endocochlear DC potential in the guinea pig.

Changes in endocochlear DC potential (EP) and potassium ion concentrations in endolymph were measured simultaneously during anoxia or during perfusion of the perilymphatic space with furosemide, 10(-2)M, in normal and kanamycin-deafened guinea pigs. The potassium ion conductance (Gk) through the cochlear partitions was calculated. Thirty minutes after the onset of anoxia, the Gk is 22.1 microM/min/mV in normal guinea pigs and 4.8 microM/min/mV in kanamycin-deafened guinea pigs. At that time the EP is -29.5 mV in normal guinea pigs and 1.4 mV in kanamycin-deafened guinea pigs. In the early stage of anoxia the rate of potassium ion concentration decrease in the endolymph per unit time is greater in normal guinea pigs than in kanamycin-deafened guinea pigs. These results suggest a rapid increase in the permeability of potassium ions in the organ of Corti in the early stage of anoxia might produce a large negative potassium ion diffusion potential or negative EP in normal guinea pigs and the failure to develop the negative EP in kanamycin-deafened guinea pigs might be due to the lack of such a rapid increase in the permeability because of the loss of the hair cells.

Animals↗
PubMed1982

Nature of the endocochlear dc potential in kanamycin-poisoned guinea pigs.

The endocochlear dc potential (EP) was measured in normal guinea pigs and in a group poisoned with kanamycin sulfate for 60 minutes after the administration of furosemide intravenously (IV) or by perfusion into the scala tympani. The EP decreased rapidly and developed a large negative potential after IV administration of furosemide, but the EP decreased more slowly and did not develop a negative potential in kanamycin-poisoned animals. With perfusion of the scala media, the EP declined slowly and did not develop a large negative potential in either group. With perfusion of the scala tympani, the EP declined slowly in the kanamycin-poisoned animals and did not develop a large negative potential, while in the normal animals the EP declined rapidly and developed a large negative potential.

Animals↗
PubMed1982

Dynamics of the flow of perilymph in the cochlea of the guinea pig.

The dynamics of perilymph flow in the cochlea was studied in guinea pigs. After placement of sodium chloride crystals on the round window membrane, the potassium ion concentration in the scala vestibuli in the basal turn does not change. The potassium ion concentrations in the scala tympani in the basal turn increases rapidly, while the potassium ion concentration in the scala tympani in the third turn increases slowly and to a lesser extent. The cochlear microphonic potential decreases in the basal turn and to a lesser extent in the third turn. After placement of sodium chloride on the fenestra in the scala tympani of the third turn, the chochlear microphonic potential in the basal turn does not change. These data lend support to the theory of longitudinal flow of perilymph in the scala tympani.

Animals↗
PubMed1981

Potentiating effects of cisplatin and ethacrynic acid in ototoxicity.

Seven milligrams per kilogram of body weight of cisplatin and 50 mg/kg of body weight of ethacrynic acid were given intravenously to guinea pigs. The threshold for Preyer's reflex, the cochlear microphonics (CM), and the endocochlear dc potential (EP) were measured during a four-day period after the injection. The changes in Preyer's reflex audiometry and the CM were more severe than that of the EP. These changes are greater than those that occur with the administration of each agent independently. The ototoxic interaction seemingly has a greater effect on the hair cells than on the stria vascularis. Baseline and periodic audiometry should be performed when both of these drugs are administered clinically.

Animals↗
PubMed1980

Vestibular fenestration and stapedioplasty in congenital stapes and vestibular window abnormality.

In this paper the results of vestibular fenestration and stapedioplasty in cases of congenital stapes deformity and vestibular window abnormality are presented. The problems in the surgical reconstruction of the middle ear transmission system, especially the importance of the areal ratio between the tympanic membrane and the vestibular window and the ossicular lever action, are discussed. The following conclusions were reached: 1. The area of the new vestibular window should be greater than 2.0 x 1.0 mm, i.e., one third of normal. 2. Hearing gain was about 1.5 times better after incus-stapedioplasty than after malleus-stapedioplasty. It is recommended that an effort be made to adopt incus stapedioplasty whenever possible.

Adolescent↗
PubMed1980

Laryngeal angiomyoma (vascular leiomyoma): clinicopathological findings.

Two cases of laryngeal angiomyoma which developed in 51 and 52-year-old men are reported. One was a tumor found in the supraglottic area of the larynx and the other was in the subglottic space. Each was a spherical tumor with a smooth surface. The chief complaints of these patients were sudden dyspnea, hoarseness, and laryngeal pain. The tumors were removed through direct laryngoscopy under general anesthesia; but in both cases, considerable bleeding occurred during and after surgery. Histological examination showed that the tumor was covered by squamous epithelium and a fibrous capsule. The parenchyma of the tumor was composed of proliferated fibers of smooth muscle, and dilated blood vessels in abundance. The tumor is of benign nature and recurrence is rare. For therapy, therefore, complete extirpation of the tumor is adequate, but the likelihood of profuse bleeding must be considered.

Hemangiosarcoma↗
PubMedDate not supplied

Anticardiolipin antibody-induced sudden profound sensorineural hearing loss.

INTRODUCTION: A link between sensorineural hearing loss (SNHL) and autoimmune disease is postulated. The association of SNHL in a patient with systemic lupus erythematosus is reported. METHODS: An adolescent female with left lateral medullary syndrome and right internuclear ophthalmoplegia was diagnosed with systemic lupus erythematosus. Treatment with prednisolone markedly improved her symptoms. Two years later, profound SNHL developed in the right ear. Extensive serologic testing was undertaken. RESULTS: Serologic tests for syphilis were false-positive. Enzyme-linked immunosorbent assay to the immunoglobulin (Ig)G anticardiolipin antibody was positive. The anticardiolipin antibody is strongly correlated with episodes of recurrent venous or arterial thrombosis. CONCLUSIONS: It appears that the anticardiolipin antibody may be associated with sudden profound sensorineural hearing loss in patients with autoimmune disease.

Adolescent↗
PubMedDate not supplied

Petrous high jugular bulb: a histological study.

PURPOSE: A high jugular bulb (JB) is thought to affect structures of the inner ear and possibly cause symptoms there, but clear histological findings of an anatomical relationship between a high JB and the inner ear have not yet been described. MATERIALS AND METHODS: We surveyed horizontal sections of 1,591 temporal bones from the collection of the Otopathology Laboratory at the University of Minnesota in Minneapolis, Minnesota, defining a high JB as a JB extending above the inferior margin of the basal cochlear turn. RESULTS: In 65 specimens (16%), we found a high JB with its vascular wall obviously thinner than that of a low JB. Bony resorption was occasionally observed around high JBs. Sixteen specimens showed a bony deshiscence between the JB and the endolymphatic sac. Clinical charts showed no obvious symptoms associated with a high JB. CONCLUSIONS: Our findings suggest that the JB may have potential to expand upward postnatally. Although our study confirmed occasional bony dehiscence between the JB and the endolymphatic sac, JBs with this involvement may have only a minor effect on function in the inner ear.

Adolescent↗
PubMedDate not supplied

Isepamicin sulfate-induced sensorineural hearing loss in patients with the 1555 A-->G mitochondrial mutation.

A mitochondrial mutation at nucleotide 1555 has been reported to be susceptible to aminoglycoside antibiotics as well as one of the causes of nonsyndromic sensorineural hearing loss. We herewith report 2 cases bearing the 1555 A-->G mitochondrial mutation who had hearing loss after short-term exposure to the new aminoglycoside antibiotic, isepamicin sulfate. Even when using aminoglycoside antibiotics with milder side effects, careful attention should be paid in applying them to patients with particular genetic backgrounds.

Adult↗
PubMedDate not supplied

Intracellular calcium suppresses mechano-electrical transduction current in chick cochlear hair cells.

Intracellular calcium concentration ([Ca2+]i) was elevated by photolysis of the caged calcium compound, Nitr-5, and by use of the intrapipette perfusion technique in hair cells dissociated from the chick cochlea. An increase in [Ca2+]i induced an outward-going current at a membrane potential of -40 mV, as recorded with an intracellular medium of 160 mM KCl. This current was carried by the Ca2+-activated K+ current. In contrast, an increase of [Ca2+]i induced an inward-going current at -50 mV with a 160 mM CsCl-based intracellular medium. This inward-going current was carried by the Ca2+-activated non-selective cation current. The amplitude of the mechano-electrical transduction current was suppressed by the increase of [Ca2+]i, achieved both by photolysis and by use of the intrapipette perfusion method.

Animals↗
PubMedDate not supplied

Development of monovalent ions in the endolymph in mouse cochlea.

The present study was designed to clarify the chronological developmental process of monovalent ions (Na(+), K(+), Cl(-)) in the endolymph of the mouse in relation to the development of the endocochlear potential (EP). The EP and ionic concentrations were measured simultaneously with the ion-sensitive double-barreled microelectrodes from the scala media of the basal turn. The EP increased abruptly 7 days after birth (DAB) and reached approximately 80 mV 14 DAB. In the earliest postnatal days, the endolymphatic Na(+) concentration was significantly higher than that in adult mice, however, the K(+) and the Cl(-) concentrations were lower. The concentrations of all the monovalent ions in endolymph reached adult levels at 7 DAB when the EP was still under 20 mV. These data strongly suggest the presence of a different mechanism between the production of monovalent ions, especially of high K(+) in the endolymph and that of EP.

Animals↗