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Biomedical subjects

K Hozawa

Publications and source records attributed to K Hozawa.

At least 37 records · Page 2Linked to original sources
PubMed1991

Effect on cochlear potentials of lateral semicircular canal destruction.

Recording of the cochlear potentials was successfully performed during experimental labyrinthectomy in the guinea pig and in three patients with acoustic neuromas during translabyrinthine removal of the tumors. In the guinea pig, complete interruption of the duct of the lateral semicircular canal including the endolymphatic canal caused little change in the endocochlear DC potential of the first cochlear turn and input-output function curve of the N1 component of the compound action potential elicited by 8-kHz tone bursts. Further drilling of the vestibular labyrinth in the guinea pig caused decline of these potentials when the vestibular was opened. In patients with acoustic neuromas, the interruption of the duct of the lateral semicircular canal hardly altered the N1 input-output function curve and N1 input-latency function curve during the 1-hour observation period. Consistent preservation of cochlear function even after interruption of lateral semicircular canals suggests the possibility of partial surgical labryrinthectomy with preservation of hearing for lesions involving semicircular canals.

Acoustic Stimulation↗
PubMed1991

The mechanism of irritative nystagmus and paralytic nystagmus. A histochemical study of the guinea pig's vestibular organ and an autoradiographic study of the vestibular nuclei.

To establish the difference of mechanism between irritative and paralytic nystagmus, alterations of Na-K-ATPase and succinic dehydrogenase activity in the vestibular sensorineural elements were investigated for 20 guinea pigs, and glucose uptake of the vestibular nuclei for 13 guinea pigs were measured by the [14C]-2-deoxy-D-glucose method. Irritative and paralytic nystagmus were experimentally provoked by introducing K+ into the perilymphatic space. From the results it was concluded that irritative nystagmus is provoked by increased excitability of vestibular sensory cells, while paralytic nystagmus is provoked by decreased excitability. However, the direction of nystagmus was eventually decided by the tonus imbalance between the bilateral vestibular nuclei. The ipsilateral vestibular nucleus was predominant during irritative nystagmus, while the contralateral vestibular nucleus was predominant during paralytic nystagmus.

Animals↗
PubMed1991

Vestibular sympathetic nervous system in guinea pig.

The vestibular sympathetic fibers were examined in 20 guinea pigs by immunohistochemical demonstration of tyrosine hydroxylase and dopamine beta-hydroxylase. The vestibular sympathetics originated in the ipsilateral superior cervical ganglion and entered the internal auditory meatus along the labyrinthine artery. At the Schwann-glial border, some of the sympathetic fibers left the artery and went into both the superior and inferior divisions of the vestibular nerves and made a loose mesh-work among the Scarpa's ganglion cells while other fibers followed the labyrinthine artery. Both types of fibers entered the crista ampularis and otoconial macula after several bifurcations in the cribrosa and terminated either near the capillaries beneath the sensory epithelial or among the vestibular nerve fibers. These fibers traveled freely in the vestibular labyrinth and were not restricted to following blood vessels or vestibular nerve fibers. Some sympathetic fibers made direct contact with the vestibular efferent fibers or the vestibular afferent fibers at the node of Ranvier. Sympathetic fibers were not observed in the sensory epithelia and semicircular canals and were rarely found in the vicinity of the dark cells: however, they were found to be distributed in the endolymphatic sac.

Animals↗
PubMed1991

Microtubule subunits of guinea pig vestibular epithelial cells.

Guinea pig cochlear supporting cells have microtubules which are composed of 15, instead of the ordinary 13, protofilaments. The microtubules form a large and stiff bundle involving abundant actin filaments to provide effective rigidity to the cell specialized for transduction of extremely high-frequent mechanical stimuli. We examined microtubules in guinea pig vestibular end organs with the transmission electron microscopy after treatment with tannic acid. Solitary microtubules occurred abundantly in the supranuclear region of type I hair cells, but sparsely in type II hair cells. Individual microtubules consisted of an ordinary set of 13 protofilaments in these hair cells as well as in the supporting cells. Supporting cells were characterized by cytoskeletal bundles of 2 to 30 microtubules which were found to be connected with actin filaments via cross-linking units. Results from the present investigation indicate that such less-organized microtubules of 13 protofilaments are sufficient for vestibular supporting cells which are specialized for detection of lower-frequency vibration together with fellow sensory cells.

Actins↗
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

Effect of high perilymphatic potassium concentration on the guinea pig vestibular sensory epithelium.

The 'rupture theory' has been proposed to explain the vertiginous attack of Meniere's disease, and the high perilymphatic potassium concentration was thought to be the most important factor in this theory. In this investigation, potassium ion was introduced through the round window into the perilymphatic space in guinea pigs by means of iontophoresis, to investigate the effect of high perilymphatic potassium concentrations on the vestibular sensory epithelium, histochemically. Following the iontophoretic procedure, spontaneous nystagmus was observed, directed toward the iontophoretic side (irritative nystagmus) for the first 10 min, and then toward the unaffected side (paralytic nystagmus) for 24 h. Both these nystagmus types were quite reversible and left no morphological change in sensory cells. However, histochemical analysis revealed an increased ATPase activity during the irritative nystagmus and decreased ATPase activity during the paralytic nystagmus in the synaptic area between the hair cells and the nerve endings of the vestibular sensory epithelium on the iontophoretic side. Judging by these results, high perilymphatic potassium concentration is assumed to affect the synaptic area of the sensory epithelium, leading to reversible nystagmus.

Animals↗
PubMed1987

Biological property of immune complex to prolong the duration of otitis media with effusion.

This study was designed to evaluate the biological properties of a light molecular weight immune complex, in comparison with that of a heavy molecular weight immune complex. Soluble immune complexes were obtained by mixing horseradish peroxidase (HRP) with guinea pig antiserum to HRP and were divided by gel filtration into several fractions according to their molecular weight (MW). After the chemotactic activity of each fraction was examined in vitro, the lightest and the heaviest MW immune complexes were injected into a guinea pig's left and right superior bulla, respectively. Although a middle ear effusion developed in both the bulla, the histopathological feature of an experimentally induced otitis media with effusion varied with the MW of the injected immune complex. The light MW immune complex proved to be a stronger inducer for a macrophage than the heavy MW immune complex, both in vitro and in vivo, and to have a tendency to persist longer in the tympanic cavity than the heavy MW immune complex. These results suggested that otitis media had a tendency to persist when a light MW immune complex was formed in a middle ear. The light MW immune complex was suspected to be involved in the pathogenesis of otitis media with effusion.

Animals↗
PubMed1987

Ultrastructural pathology of the middle ear mucosa in otitis media with effusion.

To elucidate the histopathological features of the middle ear mucosa in otitis media with effusion (OME), 33 specimens were obtained from OME patients (28 from children and 5 from adults) at the time of the ventilation tube insertion, and examined by light- and electron-microscopy. The mucosa from both pediatric and adult OME patients with glue effusion consisted mostly of non-ciliated cells containing numerous low electron-dense granules with or without a core, and many macroapocrine sections were observed on the apical surface of the cells. The mucosa with mucoid effusion showed various secretory activity, but macroapocrine secretions were rarely found. The intercellular space was intact and the junctional complex was well preserved. In serous otitis cases, the epithelia consisted mostly of cuboid ciliated cells and non-ciliated cells without definite secretory activity. But the intercellular space became widened and the junctional complex was occasionally damaged, indicating that the epithelium was quite permeable. We concluded that there was no significant histopathological difference between the OME mucosa of children and that of adults, although the nature of the effusion was closely correlated with the morphological features of the epithelial linings.

Adult↗
PubMed1987

Sensation of aural fullness and its treatment with an autonomic nerve blocking agent.

One hundred and eighteen patients (143 ears) complaining of a full sensation in the ear without any evidence of other ear diseases were selected for treatment with an autonomic nerve blocking agent and were analysed clinically. Females were extremely predominant in number, 79% of the cases. Sixty-five of 143 ears (45.4%) showed normal hearing and 54 ears (37.8%) had sensorineural hearing loss in low tone. Four mg of butropium bromide, Coliopan, an anti-cholinergic routinely used as an antispastic agent, was injected intravenously. Subsequently, the aural fullness diminished or disappeared in 72.7% (104/143) and 33.5% (48/143) was dramatically relieved within 30 min after the injection. Sensorineural hearing loss in low tone which was recognized in 57 ears in this series also improved remarkably in 57.9% (33/57). These results suggest a close relationship between the autonomic nervous system, aural fullness and sensorineural hearing loss in low tone. According to this study, we recommend anti-cholinergics as the treatment for patients, especially for women, complaining chiefly of aural fullness but with normal otoscopic findings and normal tympanogram, and with or without sensorineural hearing loss in low tone.

Adolescent↗
PubMed1986

Experimental studies on mechanism of the Menière's attack: investigation into vestibulo-cochlear response of the guinea pig induced by potassium ion.

After introducing potassium ion through the round window into the perilymphatic space of 40 guinea pigs by means of iontophoresis, physiological and histochemical investigations were performed to determine the role of the high perilymphatic potassium concentration in the vertiginous attack of Ménière's disease. About 15 min after the iontophoretic procedure, electronystagmography revealed irritative nystagmus for the first 5 min and then paralytic nystagmus for the following 6 to 24 hr. Histochemical analysis of the vestibular sensory epithelia revealed the increased activity of succinic dehydrogenase and Na-K-ATPase during irritative nystagmus and the decreased activity during paralytic nystagmus. The Na-K-ATPase activity was dominant in the synaptic area between the hair cells and the nerve-endings of the vestibular sensory epithelia. There was some delay between the reversal of nystagmus-direction and the change of enzyme activity. This delay was thought to be produced by the central regulatory mechanism for the disturbed tonus-balance in the vestibular nucleus. On the other hand, electrocochleography revealed the decrease of the action potential without any initial irritative cochlear sign, and the enzyme activity of the cochlear sensory cells was decreased from the beginning.

Animals↗
PubMed1986

Mast cell degranulation in nasal polyps.

Light- and electronmicroscopic observations as well as immunohistochemical studies were made on nasal polyps from 15 patients. The patients included 2 cases of aspirin intolerance (AA), 6 cases of allergic rhinitis (NA) and 7 cases of chronic rhinitis (CS) with negative skin tests against major inhalant allergens. Nasal polyps commonly contained many inflammatory cells such as neutrophils (PMN), eosinophils, plasma cells, mast cells, lymphocytes and macrophages. Two morphological features were conspicuous in our study: 1) PMN migration and attachment to the basal lamina, 2) accelerated degranulation of mast cells. Mean values of degranulated granules were 0.532473/micron2 in AA, 0.492615/micron2 in NA and 0.253591/micron2 in CS. These results indicate that mast cell degranulation in CS is much less than that in AA and NA. Immunohistochemical investigations revealed very few IgE-positive cells in both AA and NA, and none in CS. On the other hand IgG and IgA were frequently observed in all cases of nasal polyps. The present study suggests that mast cell degranulation plays an important role in the formation of nasal polyps, but it may not only be an IgE-dependent mechanism. To elucidate other possibilities, more extensive immunological studies will be required.

Cytoplasmic Granules↗
PubMed1985

Histopathological changes of the eustachian tube in OME animal models.

To determine whether or not stimulations of various inflammatory irritants such as endotoxin and/or immune complexes (IC) play a role in the pathogenesis of otitis media with effusion (OME), experimental animal models were examined under light and electron microscopy. Horseradish peroxidase (HRP) was chosen as an antigen and anti-HRP sera were obtained from the animals immunized by emulsions of HRP and Freund's complete adjuvant. Seventy-three albino guinea pigs and 41 chinchillas were used in this experiments. One hundred and fourteen animals were divided into three groups: forty in the active Arthus (AA) group, 61 in the passive Arthus (PA) group and 13 in the control group. According to the chronological changes of the tympanograms, it was confirmed that the pathological changes in the middle ear cleft of the OME animals persisted for at least 10-14 days after the injection, whereas those in the control animals recovered within 3-4 days. Histological examinations of both PA- and AA-group animals revealed that electron-dense HRP-positive cells, most of which were non-ciliated, were widely dispersed in the epithelium. Many inflammatory cells such as polymorphonuclear leukocyte (PMN), macrophage and plasma cells were seen in the lamina propria and some PMNs were attached to the basal lamina. Intra-epithelial infiltration of PMNs and epithelial cell degeneration associated with the disrupted basal lamina were also observed. Most conspicuous changes were found in the Eustachian tube.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗