Biomedical subjects

J Kusakari

Publications and source records attributed to J Kusakari.

At least 73 records · Page 4Linked to original sources

PubMed1987

Early effects of acetazolamide on anionic activities of the guinea pig endolymph: evidence for active function of carbonic anhydrase in the cochlea.

The effect of acetazolamide (ACZ) on HCO3- and Cl- activities in inner ear fluid was investigated by ion-selective microelectrode methods. The endocochlear potential, at 81.6 +/- 1.5 mV under normal conditions, was reduced by 4.9 +/- 0.9 mV in 30 min following the ACZ injection. The HCO3- concentrations by 11.5 +/- 1.7 mM in 30 min, while the change of Cl- level was not consistent but showed a tendency toward slight increase in average. The calculated PCO2 in endolymph was 39.6 mmHg. ACZ induced a constant elevation of the endolymph PCO2, with an increase in the venous PCO2 during the initial 20 min and thereafter the endolymph PCO2 attained a plateau despite the continuous increase of the venous PCO2. We postulate that the HCO3- secretion into the endolymph is mediated by carbonic anhydrase (CAH) and is decreased by ACZ due to the inhibition of CAH.

Acetazolamide↗

PubMed1987

Clinical report: cylindrical cell papilloma of the paranasal sinus.

We report a case of cylindrical cell papilloma of the paranasal sinuses. This tumor originated in the medial wall of the left maxillary sinus of a 69-year-old man and extended to the surrounding tissues. Pathological study of tissue sections from the tumor showed typical findings of cylindrical cell papilloma with no evidence of associated malignancy. Histochemical and electron microscopic examinations revealed a large number of mitochondria in the cytoplasm of the tumor cells. The tumor was removed through a Denker's approach. The patient did well following surgery and there has been no sign of recurrence in a 2-year follow-up study.

Aged↗

PubMed1987

Extracranial chondroma of the skull base.

We report a case of an extracranial chondroma of the skull base. This tumor occupied mainly the skull base, the nasopharynx and the parapharyngeal space. Magnetic resonance imaging was effective in diagnosis and determining the extent of the lesion. Total extirpation of the lesion was performed via an external cervical approach. A survey of the available literature revealed only three similar cases treated to date.

Aged↗

PubMed1987

The Ca2+ activity of cochlear endolymph of the guinea pig and the effect of inhibitors.

The Ca2+ concentrations in cochlear perilymph and endolymph of the guinea pig were measured with double-barreled Ca2+-selective microelectrodes and showed 1.76 +/- 0.74 X 10(-3) M and 2.20 +/- 0.19 X 10(-5) M, respectively. The electrochemical potential gradient for Ca2+ between perilymph and endolymph was 23.2 mV and the existence of an active transport mechanism from the former to the latter was suggested. Vanadate given perilymphatically decreased the Ca2+ concentration in endolymph with a slight elevation of the endocochlear potential and was suspected of blocking the active transport. The Ca2+ concentration in endolymph was abruptly increased by anoxia or the intravenous administration of 60 mg/kg furosemide and was slightly increased by the intravenous administration of 30 mg/kg furosemide or 100 mg/kg acetazolamide. The endolymphatic pH measured with pH-microelectrodes under various conditions indicates that the mechanism of increase in the Ca2+ concentration is attributed not to the liberation of Ca2+ from the surrounding tissues caused by a fall in pH but to the increased influx of Ca2+ from perilymph due to the depression of the endocochlear potential.

Acetazolamide↗

PubMed1987

Pathophysiology and prognosis of sudden deafness with special reference to the N1 latency.

Electrocochleography (ECochG) was performed in 84 patients with sudden deafness which were classified into 3 groups according to the ECochG findings, i.e. the unchanged N1 latency, the prolonged N1 latency and the absence of N1 response. The cause of hearing loss in the first group was thought to be strial, postsynaptic or mild cochlear damage and that in the second to be vascular, sensory or neural damage. The first group showed a better prognosis than those of the other two.

Adolescent↗

PubMed1987

Sensorineural hearing loss associated with hypoparathyroidism.

The hearing loss of 21 patients with hypoparathyroidism was investigated by pure tone audiometry, short increment sensitivity index (SISI) test, Békésy audiometry, speech audiometry, and auditory brain stem response. Sensorineural hearing loss was found in 7 of 21 patients (13 of 42 ears) receiving no treatment for hypoparathyroidism or having chronic hypocalcemia. The high SISI score, presence of recruitment, and prolongation of the wave I (N1) latency suggested that the inner ear is responsible for hearing loss in these cases. Inner ear dysfunction was probably due to the low calcium level in inner ear fluid and/or the direct effect of vitamin D deficiency on the inner ear.

Adolescent↗

PubMed1987

Time-related changes in cochlear potentials in guinea pigs with experimentally induced endolymphatic hydrops.

In order to examine the changes in cochlear function occurring in hydropic ears over time, endolymphatic hydrops was provoked by obliterating the endolymphatic sac in 62 albino guinea pigs. Cochlear potentials (EP, CM, SP and AP) were recorded in the 1st, 2nd, 4th and 12th postoperative weeks, respectively. A significant reduction in the level of EP was already observed in the 2nd week and the potential was further suppressed by the 4th week. There was no significant difference between the levels of the 4th and 12th weeks. The amplitudes of CM and AP decreased progressively as time elapsed after the surgery. In sharp contrast to the other potentials, the abnormality in SP was most frequently observed in the 1st week. These results are discussed in the light of the available literature.

Action Potentials↗

PubMed1987

Effect of hypothermia on the cochlear potentials.

The effects of hypothermia upon the cochlear potentials were studied in 30 guinea pigs. Particular attention was paid to the transient increase in AP amplitude at a moderate temperature. CM and AP were recorded via an Ag-AgCl lead placed on the round window membrane. Although the CM amplitude and threshold, and the AP latency and threshold were both impaired concomitant with the lowering of body temperature, the AP amplitude exhibited a transient increase at the beginning of cooling (peak at 30 degrees C) and a decrease thereafter. Narrow-band analysis of AP revealed that this phenomenon was most prominent in the high-frequency region. When the cochlear efferent fibers (crossed and uncrossed olivocochlear bundle) were cut, this transient increase in AP amplitude disappeared. This phenomenon seems to be due to the difference in sensitivity to hypothermia between the efferent and afferent fiber systems.

Action Potentials↗

PubMed1987

Cochlear potentials of guinea pigs with experimentally induced renal failure.

In order to investigate the relationship between renal failure and hearing loss, the authors made a guinea pig model with experimentally induced renal failure and examined cochlear potentials (N1, CM and EP). When renal damage was greater, the amplitudes of N1 and CM were decreased and the latency of N1 was prolonged, but EP was within normal range. The sensory cells of the cochlea were considered responsible for the hearing loss in the guinea pig model. No pathological alterations of the cochlea were revealed by a light microscopy. It is suggested that the etiology of the hearing loss was due mainly to metabolic disturbances such as uremic toxins, electrolyte imbalance or endocrine abnormalities.

Acute Kidney Injury↗

PubMed1987

The effect of vitamin D deficiency on the cochlear potentials and the perilymphatic ionized calcium concentration of rats.

Sensorineural hearing loss has been frequently reported in patients with renal failure but its etiology has not yet been established. Disturbance of Ca metabolism is present in renal failure and seems to cause hearing loss. The purpose of the present study was to determine whether the disturbance of Ca metabolism has any effect on cochlear function. The cochlear potentials were measured in 19 rats fed with a vitamin D deficient diet. The pathological findings showed prolongation of N1 latency with unchanged N1 amplitude and pseudothreshold, depression of CM amplitude and elevation of the CM pseudothreshold. The latencies of narrow-band APs were prolonged in the entire cochlear partition. Ca2+ concentration in perilymph was 3.2 X 10(-4) M (n = 4) in vitamin D deficient rats and 7.4 X 10(-4) M (n = 4) in the controls. These findings were milder than those obtained in surgically induced renal failure. It was concluded that although vitamin D deficiency is one cause of hearing loss in renal failure, other major factors must be involved. The authors postulate that hearing loss in vitamin D deficiency is mainly attributable to the depression of the Ca2+ concentration in perilymph.

Action Potentials↗

PubMed1987

Sound perception in the ultrasonic region.

The mechanism of ultrasonic perception was investigated electrocochleographically in guinea pigs (1) to compare AP responses in normal animals with those in kanamycin-poisoned animals with a damaged outer hair cell system; (2) and to analyse the masking property of continuous ultrasonic sound upon the AP evoked by burst stimuli within the auditory field. The study revealed several facts indicating the breakdown of cochlear sharp frequency analysis in the transduction of ultrasonic sound. We concluded that the sound perception in the ultrasonic region could be performed by the inner hair cell system without any enhancement or modulation of the outer hair cell system, which was regarded as an important process in a recent model of cochlear micromechanics.

Action Potentials↗

PubMed1987

Topographic diagnosis of facial paralysis by the assay of lysozyme concentration in tears.

Lysozyme in tears is secreted from the main lacrimal gland innervated by a parasympathetic nerve via the greater petrosal nerve. Lysozyme activity in tears was analysed in 10 cases of unilateral facial paralysis due to the cerebellopontine angle (CPA) tumor and 10 normal cases. The lysozyme concentration in tears on the paralysed side collected by Schirmer No. 2 test was significantly lower than that on the healthy side, or bilateral sides of normal subjects. This decreased concentration on the paralysed side is due to the interruption of the reflex are at the level of CPA. It is concluded that our new method is more useful for topographical diagnosis of facial paralysis than is the conventional Schirmer's filter paper test.

Adult↗

PubMed1987