Biomedical subjects

K Hisashi

Publications and source records attributed to K Hisashi.

23 records · Page 2Linked to original sources

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↗

PubMed1990

[Effect of potassium canrenoate on the EP and Na+, K+ activities in endolymph].

The perilymphatic space was perfused with artificial perilymph containing 5 x 10(-3)M potassium canrenoate. The EP, K+ and Na+ activities in the scala media were measured with double barrelled K+ or Na+ selective microelectrode. Following the onset of the perfusion, the EP gradually declined and was stable after about 20 minutes. K+ activity also declined gradually but Na+ activity was unchanged. When the EP became stable, the artificial ventilation was stopped. The EP dropped to a large negative potential and K+ activity decreased gradually, but Na+ activity increased by degrees. The same results were observed in the untreated animals when the ventilation was stopped. There are no pathological changes both in the TEM view of the stria vascularis and in the SEM view of the hair cell. These results suggest that this drug may affect K+ conductance of the stria vascularis specifically.

Animals↗

PubMed1989

Balloon test occlusion of the internal carotid artery with monitoring of compressed spectral arrays (CSAs) of electroencephalogram.

We used the compressed spectral arrays (CSAs) of the electroencephalogram (EEG) to monitor cerebral blood flow related events in balloon test occlusion of the internal carotid artery (balloon Matas test). Reliability of the CSAs was examined in 22 patients subjected to the test. Of 9 patients who underwent subsequent permanent carotid occlusion, in 6 there was no change on CSAs and/or in neurological conditions. In 2 patients, there was a slowing on CSAs prior to the appearance of neurological deterioration during clinical testing. CSAs transformed these EEG changes into a succinct graphic display. In 1 of the 2, for whom the Matas test was repeated 1 year later, there was a change from positive to negative and delayed cerebral infarction occurred after carotid occlusion. In the other patient, an ischemic insult occurred during the balloon occlusive procedures. The third patient had a fatal delayed ischaemic complication 3 days after surgical ligation of the cervical carotid artery, despite the negative balloon Matas test. Complications in these 3 patients were presumably related to thromboembolic mechanisms. The balloon Matas test monitored by CSAs is useful for detecting change in brain functions attributed to an inadequate blood flow. However, this test is unreliable for predicting thrombo-embolic complications.

Aged↗

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

Movement of monovalent ions across the membranes of marginal cells of the stria vascularis in the guinea pig cochlea.

The resting potential and monovalent ions in the marginal cells and scala media were measured before and 20 min after the onset of anoxia using ion-sensitive microelectrodes. The resting potential of the marginal cells decreased from 62.7 to -2.4 mV. The K+ activity decreased from 77.7 to 53.2 mEq/l, while the Na+ activity increased from 2.6 to 24.7 mEq/l. The Cl- activity did not change significantly. In the scala media, the endocochlear potential decreased rapidly from 80.9 to -28.0 mV after the onset of anoxia. The K+ activity decreased from 119.0 to 96.5 mEq/l, the Na+ activity increased from 1.3 to 9.5 mEq/l and that of Cl- decreased from 127.0 to 115.1 mEq/l. The electrochemical gradients determined for each ion based on the ionic changes in the scala media and marginal cells, suggested the existence of an Na/K pump and Na-K-2Cl cotransport at the basolateral membrane of the marginal cells, and a rheogenic K pump and Na-K-2Cl transport at the luminal membrane of the marginal cells. The Na+ and K+ must be recycled at the basolateral membrane and luminal membrane of marginal cells, respectively.

Animals↗