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Biomedical subjects

H Shinkawa

Publications and source records attributed to H Shinkawa.

At least 55 records · Page 3Linked to original sources
PubMed1995

Expression of substance P, CGRP, and GABA in the vestibular periphery, with special reference to species differences.

The present study was conducted to elucidate species differences in the distribution of neuroactive substances, including substance P (SP), calcitonin gene-related peptide (CGRP) and gamma-aminobutyric acid (GABA), in the vestibular periphery of various animals (chicken, pigeon, rat, guinea pig and squirrel monkey). SP-like immunoreactivity was found in a subset of the primary vestibular afferents with no marked species differences in the staining pattern. In contrast, the localization of CGRP- and GABA-like immunoreactivities in the efferent nerve fibers varied according to species. This difference in the distribution pattern of neuroactive substances, found in the efferent system, may indicate that each species has a chemically (and probably functionally) distinct efferent system which is related to its specific environment and/or evolution.

Animals↗
PubMed1995

Neuroactive substances in the human vestibular end organs.

In order to evaluate the involvement of neuroactive substances in the human vestibular periphery, the immunocytochemical distribution of substance P (SP), calcitonin gene-related peptide (CGRP), and choline acetyltransferase (ChAT) was examined. SP-like immunoreactivity (LI) was present around and beneath sensory hair cells, probably corresponding to their afferent nerve endings. SP-LI was found predominantly in subpopulations of the primary afferents distributed in the peripheral region of the end organs. ChAT-LI and CGRP-LI were found throughout as small puncta below the hair cell layer, probably corresponding to efferent endings. The present results indicate that these neuroactive substances, previously described in animals, are also distributed in the human vestibular periphery, and almost certainly contribute to human vestibular function.

Calcitonin Gene-Related Peptide↗
PubMed1995

Observation of positional nystagmus with infrared CCD camera.

Using infrared CCD camera and electronystagmography we analyzed positional nystagmus in 33 patients with peripheral positional vertigo. Patients were classified into three types; (a) lateral type: nystagmus occurs in lateral position, (b) sagittal type: nystagmus occurs in head-hanging position (so-called benign paroxysmal positional vertigo, BPPV), and (c) mixed type. Nystagmus in the lateral type was horizontal and that in the sagittal type was rotatory. In all types, the vertigo and nystagmus began with a few seconds' latency after head tilt and briefly increased to a maximum, and then gradually decreased. The duration of horizontal nystagmus in the lateral and mixed type was significantly longer than that of rotatory nystagmus in the sagittal type mixed type. The mean value of the former was 90.6 s and that of the latter 18.1 s. We suggest that the velocity storage mechanism of the horizontal vestibulo-ocular reflex (VOR) is considerably different from that in the vertical VOR.

Adolescent↗
PubMed1994

MSG5, a novel protein phosphatase promotes adaptation to pheromone response in S. cerevisiae.

Pheromone-stimulated yeast cells and haploid gpa1 deletion mutants arrest their cell cycle in G1. Overexpression of a novel gene called MSG5 suppresses this inhibition of cell division. Loss of MSG5 function leads to a diminished adaptive response to pheromone. Genetic analysis indicates that MSG5 acts at a stage where the protein kinases STE7 and FUS3 function to transmit the pheromone-induced signal. Since loss of MSG5 function causes an increase in FUS3 enzyme activity but not STE7 activity, we propose that MSG5 impinges on the pathway at FUS3. Sequence analysis suggests that MSG5 encodes a protein tyrosine phosphatase. This is supported by the finding that recombinant MSG5 has phosphatase activity in vitro and is able to inactivate autophosphorylated FUS3. Thus MSG5 might stimulate recovery from pheromone by regulating the phosphorylation state of FUS3.

Adaptation, Physiological↗
PubMed1994

[Vestibular function in bilateral idiopathic progressive sensorineural hearing loss].

To investigate vestibular function in patients with bilateral progressive sensorineural hearing loss (BPSHL), we examined 5 cases using electronystagmography. Cases 1, 2 and 3 were adult type, cases 4 and 5 were juvenile type. All patients had dizzy spells in the early stage of the disease, and showed spontaneous nystagmus. Bilateral reduction of caloric response and very low VOR (vestibulo-ocular reflex) gain on rotation testing were observed in cases 1, 2 and 3. Case 4 showed right canal paresis on the caloric test and left directional preponderance on the rotation test. Case 5 showed good responses to both tests. Optokinetic afternystagmus (OKAN) in cases 2, 3 and 5 was not brisk, and cases 1 and 4 showed directional preponderance of OKAN. Although OKAN is useful for detecting directional preponderance, it does not always reflect peripheral vestibular function. We suggest the existence of two types of BPSHL which correlate with vestibular function. One type is associated with high grade vestibular dysfunction while, in the other, vestibular function is fair.

Adolescent↗
PubMed1994

[Influence of superior cervical ganglion stimulation of vestibular function].

The sympathetic nervous system, which originates in the superior cervical ganglion (SCG) and is distributed in vestibular end organs, has been proposed to have some influence on vestibular function. The present investigation was conducted to assess the effects of unilateral electrical stimulation of the SCG, administration of a vasopressor drug, and introduction of KCl (0.7 M/ml) into the tympanic cavity on vestibular function in alert guinea pigs. Nystagmus was not observed as result of electrical irritation of the SCG (22 test animals), infusion of the KCl solution into the middle ear cavity (5 test animals), or the combination of SCG stimulation and vasopressor drug administration (7 test animals). However, when the SCG was stimulated electrically after introduction of the KCl solution into the ipsilateral cavity, nystagmus and postural deviation were observed (5 out of 12 animals). Furthermore, after the administration of a vasopressor drug to these 12 animals, irrespective of the manifestation of nystagmus, the same changes took place in response to the electrical stimulation (7 animals). These results suggest that SCB stimulation is a provocative factor for nystagmus, that infusion of KCl solution into the tympanic cavity induces a hypersensitive state in the inner ear, and that high blood pressure increases this hypersensitivity.

Animals↗
PubMed1993

Differences in size and shape between the right and left sigmoid sinuses.

Whether or not the shape and size of the sigmoid sinus are affected by middle ear inflammation is still controversial. Using high-resolution computed tomography (CT), we examined the shape and cross-sectional area of the sigmoid sinus in 80 patients with unilateral chronic otitis media. Forty patients had right otitis media, and the others left otitis media. Whether chronic inflammation involved the right or left ear, a protrusive type of sigmoid sinus was found more frequently on the right than the left, while the cross-sectional area was significantly greater on the right. These findings suggest that a side difference affecting the sigmoid sinus would thus appear not to be caused by postnatal otitis media, but to originate in fetal life. The shape of the sigmoid sinus greatly varies among individuals and according to whether it is on the right or the left. Findings also indicate that a temporal bone CT is desirable to optimize surgical safety.

Adult↗
PubMed1993

Immunocytochemical localization of substance P and neurofilament proteins in the guinea pig vestibular ganglion.

To examine the cytochemical features of primary vestibular afferent neurons, we examined the immunocytochemical distribution of substance P(SP) and neurofilament proteins (NFP) in the guinea pig vestibular endorgans and ganglion. 84.9% of vestibular ganglion cells showed SP-like immunoreactivity. SP immunoreactive cells were small in diameter (25.4 microns), and randomly distributed in the ganglia. NFP immunoreactive cells (34.2%) were relatively large in diameter (31.1 microns). By double-staining immunocytochemistry it was possible to distinguish three different cell types: SP-positive/NFP-negative, SP-negative/NFP-positive, and SP/NFP-positive vestibular ganglion cells. Vestibular ganglion cells can thus be classified on the basis of size and immunocytochemical characteristics. These chemically distinct subpopulations of vestibular ganglion cells may be an indication of functional differences within vestibular afferent neurons.

Animals↗
PubMed1993

Immunocytochemical localization of intermediate filaments in the guinea pig vestibular periphery with special reference to their alteration after ototoxic drug administration.

The present study examined the immunocytochemical localization of various intermediate filaments (IFs), 68 kDa, 160 kDa and 200 kDa neurofilament protein (NFP), cytokeratin (CK) 1, 8, 10 and 19, vimentin, and glial fibrillary acidic protein (GFAP) in the vestibular end-organs and ganglia of normal and streptomycin-treated guinea pigs. In normal animals, 68 kDa, 160 kDa and 200 kDa NFP were found in afferent nerve fibers and nerve terminals (probably nerve chalices). Fine nerve fibers (probably efferent and/or sympathetic nerve fibers) were also immunoreactive to NFP. In the vestibular ganglia, 68 kDa and 160 kDa NFP were predominantly distributed in larger cells, whereas 200 kDa NFP was also found in some small ganglion cells. Cytokeratin 8 and 19 were located in supporting cells, transitional cells, dark cells of vestibular end-organs, and the epithelial cell lining of the membranous labyrinth. Vimentin was observed in the hair cells distributed in the central region of the end organs, supporting cells, most connective tissue cells, and Schwann cells of the vestibular ganglion. Although GFAP-like immunoreactivity was evident in glial cells of the proximal vestibular nerve, no immunoreactivity was detected in the distal portion of the vestibular nerve, vestibular ganglion, or vestibular end-organs. These highly distinct staining patterns of IFs indicated that they may play different roles in the different cell types, and that they may serve as a specific marker for each cell type. In streptomycin-treated guinea pigs, immunoreactivities for NFP and vimentin (found in the hair cells) decreased after treatment, whereas immunoreactivities for the other IFs were not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Middle ear inflation with a gas mixture.

We studied the middle ear (ME) pressure in 13 atelectatic ears to evaluate the effect of politzerization or ME inflation by a catheter using both room air and a gas mixture. The gas contained 12% O2, 6% CO2 and 82% N2. Tympanometry was performed before and after the treatment. The elevated ME pressure induced by the treatments, whether with room air or the gas mixture, declined rapidly within the first 30 min. However, at 35 and 45 min after the treatment with room air, the mean decrease in pressure was significantly greater than with the gas mixture, which might be due to slow oxygen absorption through the ME mucosa.

Acoustic Impedance Tests↗
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

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↗
PubMed1991

Microtubules of guinea pig cochlear epithelial cells.

By tannic acid staining, the 13-protofilament composition of cochlear hair cell microtubules, an impressive contrast against the 15-protofilament microtubules in cochlear pillar cells, was verified. The 15-protofilament microtubules formed a large and stiff cytoskeletal bundle in pillar cell bodies involving abundant actin filaments. The bundles were always situated vertically, i.e., longitudinally to the cell body axis, and were most numerous in the outer as well as the inner pillar cells in the basal turn, decreasing gradually toward the apex. Such gradient architecture of the pillar cell cytoskeleton can be correlated with the tuning mechanism for traveling waves of sound containing variable frequencies.

Animals↗
PubMed1990

The effects of pressure on cochlear microphonics in experimentally induced hydropic ears in the guinea pig.

The effect of perilymphatic pressure on the cochlear microphonics (CM) threshold was examined in guinea pigs with experimentally induced hydrops. When a pressure of 300 mm H2O was applied to the scala tympani of the basal turn, the 500 Hz CM threshold shifts in ears during the 1st week following obliteration of the endolymphatic sac and duct were significantly smaller when compared with shifts in normal ears. Larger threshold shifts were then regained at 4-12 weeks after surgery. When acetazolamide was administered to hydropic animals, the effect of the increase of perilymphatic pressure on the CM threshold was also investigated. During the 1st postoperative week (4-7 days after surgery), CM threshold shifts were larger when compared to changes in hydropic animals without medication. The CM depression as the result of pressure is probably due to a mechanical effect on the intracochlear partition.

Acetazolamide↗
PubMed1990

Changes in tympanograms after middle ear inflation.

To determine the effects of politzerization or middle ear (ME) inflation by a catheter, we studied the ME pressures in 35 ears with retracted tympanic membranes (29 patients). Serial tympanometries were performed prior to the ME inflation and immediately, 10, 20, 30 and 60 min after the procedure. The present study showed that the more negative the ME pressure was before the inflation, the greater the pressure change was after the treatment. The elevated ME pressure induced by the procedure declined rapidly within the first 20 min after the inflation. This was probably caused mainly by spontaneous elimination of ME gas through the eustachian tube and gas absorption from the ME mucosa. During the post-inflation course, some ears demonstrated more negative pressures in the ME cavity than those before the inflation. The present investigation demonstrated that the use of inflation to treat secretory otitis media had short-term benefits which could be improved by minimizing gas absorption.

Acoustic Impedance Tests↗
PubMed1990

Is change in middle ear air volume following ventilation tube insertion a reliable prognostic indicator?

Ninety ears (52 patients, aged 3-11 years) affected by secretory otitis media (SOM) were treated by insertion of a ventilation tube (VT). Following VT insertion, the middle ear air volume of these ears was estimated by using an impedance audiometer, at 1, 3, and 6 months postoperatively, and every 6 months thereafter. The middle ear air volume, expressed as the compliance value, increased rapidly for the first 3 months, followed by a gradual increase thereafter. A great difference was observed among the compliance values of ears, ranging from over 10 cc to below 1.5 cc at 6 months, postoperatively. Twelve percent of the ears had compliance values of less than 1.5 cc, and in this group, CT showed opacified and poorly developed mastoid cells. Although the association of upper respiratory disorders such as chronic sinusitis, nasal allergies and cleft palate were found to be more frequent in cases of ears with smaller compliance values, this was not statistically significant. Small compliance values (middle ear air volume) were correlated with the early onset of acute or secretory otitis media, repeated otorrhea after VT insertion and high recurrence rates after the extrusion of the VT.

Child↗
PubMed1990

[Middle ear air volume and prognosis of secretory otitis media].

Ninety ears (52 patients, aged 3-11 years) affected by secretory otitis media (SOM) were treated by insertion of ventilation tubes (VT). Following insertion of the VT, middle ear air volume of these ears was estimated using an impedance audiometer, at 1, 3, and 6 months postoperatively, and every 3 months thereafter. The middle ear air volume, expressed as the compliance value, increased rapidly for the first 3 months followed by a gradual increase thereafter. A great difference among the compliance values of ears was observed, values ranging from over 10 cc to below 1.5 cc at 6 months, postoperatively. Twelve percent of the ears had compliance values of less than 1.5 cc, and in this group, CT showed opacified and poorly developed mastoid cells. Although the association of upper respiratory disorders such as chronic sinusitis, nasal allergies and cleft palates were found to be more frequent in cases of ears with smaller compliance values, this was not statistically significant. Small compliance values (middle ear air volume) were correlated with the early onset of acute or secretory otitis media, repeated otorrhea after VT insertion and high recurrence rates after the extrusion of the VT.

Air↗