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Biomedical subjects

J Kusakari

Publications and source records attributed to J Kusakari.

At least 91 records · Page 5Linked to original sources
PubMed1985

Ultrasonic electrocochleography in guinea pig.

In order to obtain information about how ultrasonic stimuli are perceived (USP) in man, guinea pig cochleae were stimulated by bone conduction with frequencies (98.8 and 143.5 kHz) above the normal auditory field of this animal. The cochlear potentials recorded consisted of CM, SP and AP originating from the basal turn of the cochlea, and were found to be influenced by asphyxia, administration of ethacrynic acid, hypothermia and change of interstimulus interval. In addition, in kanamycin-treated animals the mean AP amplitude decreased to about one fourth of the normal value, and the mean AP latency increased significantly. These findings suggest that there is no special sense organ for the detection of USP but that such sounds activate hair cells in the basal turn of the cochlea.

Animals↗
PubMed1985

Gas analysis of the middle ear cavity in normal and pathological conditions.

The gas of the tympanic bulla was measured using 18 normal and 14 tube-obstructed guinea pigs. The concentrations of CO2 and O2 were 4.8 +/- 1.0% and 7.2 +/- 1.8% in normal animals, and 4.3 +/- 1.6% and 8.1 +/- 2.0% in tube-obstructed animals, respectively. The bulla was opened to room air and then closed again. The recovery process of each gas was examined. In normal animals, CO2 and O2 were exponentially changed toward the pre-open value with time. The time constants of this recovery process were 15 min and 97 min in CO2 and O2, respectively. In tube-obstructed animals, however, this quick recovery of CO2 was significantly delayed (time constant, 50 to 80 min), although there was no effect upon the recovery of O2. This delayed recovery of CO2 is likely to be due to the edema of the mucous membrane.

Animals↗
PubMed1985

[A case of basal encephalomeningocele (a transethmoidal type) containing the olfactory nerve].

An experience of operative case of basal (transethmoidal type) encephalomeningocele is reported. A 3-year-old boy complained of continuous, spontaneous cerebrospinal fluid rhinorrhea and right intranasal mass lesion. The rhinorrhea began when one year old. He suffered from meningitis at the age of two. When he was three years old, the intranasal mass and CSF rhinorrhea were perceived. On admission he had normal general status and no abnormality in neurological examination. The usual axial computed tomography showed a small mass in the intranasal cavity. But the continuity between the mass and brain parenchyma was not detected in this study. Metrizamide CT cisternography demonstrated it. Coronal CT scan visualized it more directly. We performed operation using bifrontal craniotomy and subfrontal approach. Brain parenchyma did not protrude into the frontal cranial base and expanding right olfactory nerve penetrated into the small defect at the right cribriform plate. The olfactory nerve was extracted as much as possible. The defect was filled with a few piece of muscle and coating with the adhesive agent was performed. Histological findings of operative specimen were abnormal olfactory nerve, normal brain tissue and arachnoid membrane. Post-operative state was uneventful. CSF rhinorrhea disappeared. Post-operative direct sagittal computed tomography visualized the encephalomeningocele extremely. Biopsy of the intranasal mass revealed brain tissue covered by normal nasal epithelium. Basal encephalocele is rare in Japan. We found 10 cases in the literature. It is important that we do not forget basal encephalocele in the difference of intranasal tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed1984

Effect of kainic acid upon N1 latency.

Although the N1 latency of whole nerve action potential is one of the important pieces of information obtained from ECochG, there are some conflicting opinions as to whether or not it is prolonged in sensorineural hearing loss. Kainic acid (KA) is known to destroy neurons selectively through an action at glutamatergic synapses. Therefore, a model of "neural deafness" was made by perfusing the scala tympani with KA solution. The effect of KA upon cochlear microphonics was minimal. Although the N1 amplitude was markedly suppressed by KA, the N1 latency was neither prolonged nor shortened. The result obtained in the present study strongly suggests that the N1 latency is not prolonged in "neural deafness."

Animals↗
PubMed1984

Effect of hypothermia upon the electrocochleogram and auditory evoked brainstem response.

The effects of hypothermia upon electrocochleogram (ECochG) and auditory evoked brainstem response (ABR) were studied in 10 children who underwent the open heart surgery under hypothermic anesthesia. The latencies of N1, waves III and V in response to click of 115 dB p.e. SPL were prolonged at the rate of 0.12 +/- 0.02, 0.25 +/- 0.04 and 0.43 +/- 0.05 msec/degree C, respectively. The N1 amplitude was initially increased, returned to the precooling value at about 26 degrees C and decreased thereafter. SP was increased in amplitude by hypothermia and never disappeared throughout the observation. At the time of rewarming, SP appeared first, followed by N1 and finally by waves III and V. The results obtained in the present study were discussed in the light of the sensitivity of the sensory hair cells, peripheral nerves and CNS to the hypothermic condition.

Anesthesia, General↗
PubMed1983

Generation mechanism of the negative endocochlear potential during early stage of anoxia.

To investigate the generation mechanism of the -EP in anoxic cochlea, the perilymphatic space was perfused with solution of various K+ concentrations in 38 guinea pigs when the -EP was maximally reduced by anoxia. Although the perfusion of scala tympani and vestibuli with Ringer-Locke solution or that of scala vestibuli with 154 mM K+ solution did not have any effect upon the -EP, the potential was elevated to 0 mV when the scala tympani was perfused with 154 mM K+ solution. Furthermore, the elevation of the potential was less remarkable when the K+ concentration in perfusate was reduced. The level of the potential during perfusion was closely related to K+ concentration in perfusates. The present results strongly suggest that the -EP is the result of the K+ diffusion potential and this diffusion mechanism is performed through the organ of Corti.

Animals↗