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Biomedical subjects

T Morimitsu

Publications and source records attributed to T Morimitsu.

At least 19 recordsLinked to original sources
PubMed1992

Venous drainage through the internal auditory meatus of the guinea pig cochlea.

The angioarchitecture of the guinea pig cochlea has been investigated closely using light microscopy and resin injections. However, detailed information concerning the vasculature of the modiolus is still unavailable, and even the existence of venous drainage through the internal auditory meatus is not agreed upon. In the present investigation, vascular casts of guinea pig temporal bones were studied using scanning electron microscopy. A vessel, formed by the confluence of the vascular network on the modiolar wall and having a spiral course into the internal auditory meatus was found in the modiolus of the basal turn. The vessel had a venous pattern on its cast surface and, after existing from the internal auditory meatus, drained finally into the dural sinus. These scanning electron microscopic findings were confirmable by serial sections of the dural veins in the internal auditory meatus and the modiolus. The vessel found may correspond to the so-called internal auditory vein, but it would be more appropriate to call it "the vein of the internal auditory meatus," since it appears to be an independent route of venous drainage from the modiolus.

Animals↗
PubMed1992

Histopathology of eighth cranial nerve of mass stranded dolphins at Goto Islands, Japan.

We examined four dolphins (Grampus griseus) of 582 mass-stranded. Almost no contents were found in the alimentary canal. Nasitrema gondo and Crassicauda grampicola were found in the tympanic cavity. Severe degeneration of the eighth cranial nerve was observed microscopically in all animals and an egg of Nasitrema was found in a tissue crevice of the nerve. We propose that the nerves were damaged directly by Nasitrema.

Animals↗
PubMed1992

Clinical application of a newly developed surveying system for designing and fabricating removable partial dentures.

In this paper, some problems in commercially available surveying systems were discussed, and a clinical technique for designing and fabricating clasps by using an improved 'Digital Surveyor' and a computer system were presented. This system has the advantages as follows: (1) morphological factors on abutment teeth could be measured and evaluated using the improved 'Digital Surveyor' and its accessories set, (2) clasps providing with proper mechanical properties according to various conditions in the mouth could be designed and fabricated precisely and easily. It became clear that conventional surveying methods involved empirical rules should be re-examined and replaced by the more rational surveying method like this system.

Computer-Aided Design↗
PubMed1992

Three dimensional shape measurement system for residual ridges.

It is very important for design and construction of complete dentures to evaluate the condition of residual ridges of edentulous patients objectively and precisely. The authors have been developing a shape measurement system for residual ridges. In this study, the outline of the system is described and the accuracy of the system is evaluated. The system consists of a high precision laser displacement meter, a working table and its controller, and a personal computer. The working table, on which a plaster model is placed, can move until the end of the moving range at a speed of 0.7 mm/sec. The height of the plaster model was measured intermittently with a frequency of 7 points/sec. To determine the accuracy of this system, experimental plaster models, which simulated the simplified shape of residual ridge, were measured and analyzed. The measurement error was 2.5%, which seemed to be highly accurate. The accuracy of the measurement decreased with the darkness of the color of the plaster model.

Alveolar Bone Loss↗
PubMed1991

Myringoplasty in children.

Our 11 years of experience of myringoplasty in 87 children aged 3 to 14 years were retrospectively studied. The children were followed up over a period of 3 years. Children in the 3-to-12-year-old age group had a success rate of 57.7%. Graft-take rate was 100% in children operated on at the age of 13 and 14 years. Revision surgery was needed in 33 ears, and ultimate success was achieved in 88.9%. Within the same period, 38 ears were conservatively treated and 20 perforations of them were spontaneously closed. The state of the opposite ear and the perforation size were not a decisive factor in the results of myringoplasty. Children between 7 and 10 years old with small mastoid pneumatization had a statistically lower graft-take rate. We concluded that myringoplasty is warranted for children 13 years of age and older or children aged 7 to 12 years with large mastoid pneumatization.

Adolescent↗
PubMed1990

Long term effects of intense sound on endocochlear DC potential.

Changes in endocochlear DC potential (EP) after single and repeated intense sound exposure and negative EP induced by anoxia were observed in guinea pigs with passage of time. The intense sound used was a pure tone of 2 kHz at 145 dB SPL for 4 h. The single exposure group was divided into 8 groups of 1, 2, 5, 10, 20, 30, 45, and 60 days after sound exposure. The EP level dropped remarkably in the 1 and 2 day groups and recovered almost completely in the remaining groups. In the 60 day group, EP was significantly higher than that of the control group. The double exposure group consisted of 1, 2, 5, 10, 20, and 30 day groups after the second exposure at an interval of 30 to 40 days. EP in the 1, 2, 5, and 10 day groups was significantly lower than the control level and in the 20 and 30 day groups was almost the same as that of the controls. In all groups after single and double sound exposure, disappearance of negative EP during anoxia was observed. The EP decrease after sound exposure was apparently caused by a mechanical but reversible lesion at the stria vascularis. The disappearance of negative EP after sound exposure was thought to be induced by an irreversible lesion of Corti's organ.

Animals↗
PubMed1990

Long-term effects of intense sound on hair cells of Corti's organ and endocochlear DC potential.

Cochleograms of guinea pig ears were made 30-40 days after exposure to intense pure tones of 300 Hz, 500 Hz, 2 kHz, or 4 kHz at 130-150 dB SPL for 4-24 h. At 4 kHz, hair cells in the basal turn disappeared totally, in the second turn moderately, and were relatively undamaged in the third and apical turns. At 500 Hz, hair cells in the second and third turns were almost completely injured and at 300 Hz moderately damaged in the third and apical turns although the basal turn remained undamaged. At 2 kHz for 9 h, hair cells were almost completely injured in all turns. Negative endocochlear DC potential (negative EP) induced by furosemide was observed in the basal turn but not in the third turn of animals exposed to 300 Hz. Contrarily, negative EP was observed in the third turn but not in the basal turn of animals exposed to 4 kHz. We conclude that the hair cells of Corti's organ play an essential role in the production of negative EP.

Acoustic Stimulation↗
PubMed1990

[Phinocerebral mucormycosis--report of a case].

Rhinocerebral mucormycosis is a rare and fatal deep fungus infection occurring in debilitated patients. Its reports have been recently increased because of the increase of such conditions as uncontrolled diabetics, leukemia, and cancer. A 60-year-old male suffering from continuous headache and fever was diagnosed as meningitis, and repeated culture of cerebrospinal fluid was negative. Antibiotic therapy was ineffective. CT scan revealed brain abscess in the right frontal lobe and bone defect over the right posterior ethmoidal sinuses. Both maxillary and ethmoidal sinuses were operated on 38 years ago. The patient was suspected to have rhinologic brain abscess. We intended to remove the source of infection in the right posterior ethmoidal sinuses beneath the base of the skull and to repair the defect of dura mater. The operation was tried on the 6th hospital day. There was a cyst in the posterior ethmoidal sinuses and an intact denuded dura mater over the cyst. The causative organism was not detected by smear test, bacteriological and fungal culture. He relapsed into lethargy, and died on the 21st hospital day due to the vast cerebral infarction. Autopsy revealed rhinocerebral mucormycosis. The literature on this disease was also reviewed and discussed.

Brain Abscess↗
PubMed1990

[Electron microscopic study on calcification of porous hydroxyapatite ceramics implanted in the submandibular glands of rats].

This study was primarily designed to determine the tissue responses and the initial calcification profiles after the implantation of porous hydroxyapatite ceramics (HAP), and secondly, to find out the effects of chronic isoproterenol (IPR) administration on them. For the experiment 1, several granules of HAP were implanted in the submandibular glands of rats and for another experiment 2, chronic IPR administration was carried out to rats implanted HAP. The surrounding tissues of HAP implanted and the insides of its pores were observed and analyzed with a light microscope, an electron microscope and an analytical electron microscope one and three days, and five, eight and ten weeks after treatment. The results were as follows: 1. The outer layer of HAP was encapsulated by granulation tissues due mainly to the infiltration of inflammatory cells one and three days after treatment. Subsequently, the encapsulation was further enhanced by fibrous cells and collagen fibers, whereas no obstructive reactions were seen in the surrounding tissues of HAP implanted. 2. From the first day after treatment, tissue fluid-like matrix substances permeated inside HAP and at the same time, blood cells, phagocytic and mesenchymal cells were detected within the whole HAP. 3. Especially, in the layer within 100-200 microns inside the pores of HAP, a number of fibroblasts, collagen fibers and osteoblast-like cells were observed. 4. Within the pores with cells infiltrated into HAP, a layer, suggestive of the precipitation of calcium-phosphate salts, was formed from one week after treatment. By five weeks, particularly within the layer, amorphous substances with the high density were observed in general and, by eight and ten weeks, the substances were further increased in thickness. 5. By eight and ten weeks, amorphous substances with the high density were observed in a line with collagen fibers and around the cells within HAP. 6. The amorphous substances with the high density were calcified substances consisting of mainly Ca and P, as observed by an elemental analysis. 7. By administration of IPR, most of the acinar cells and the cells in the pores became degenerative after about five weeks and less calcified substances were observed along the collagen fibers. However, as seen in the experiment 1, calcified substances were also found in the precipitated layer within matrix-like substances of the pores.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

The effects of anesthesia of the tympanic membrane on eustachian tube function.

In our previous histological studies of the tympanic membrane, we reported the presence of encapsulated nerve corpuscles that are capable of detecting middle ear pressure. Based on these findings, the relation between sensory receptors in the tympanic membrane and tubal function was examined in a clinical study. Tubal function was tested during Valsalva maneuvers and its active equilibration. Function was recorded as a change of the static compliance of the tympanic membrane on an otoadmittance meter. To paralyze the sensory receptors in the tympanic membrane, iontophoresis was used to induce anesthesia of the drum. Forty ears of 20 subjects were tested. All ears were able to equalize positive middle ear pressure without or with a single swallowing. After anesthesia, 13 ears needed more than two swallows and 4 ears failed to equalize middle ear pressure in spite of repeated swallowings. As eustachian tube function changed following anesthesia of the tympanic membranes, a neural connection between sensory receptors in the tympanic membrane and tubal muscles is suggested.

Acoustic Impedance Tests↗
PubMed1989

Pathogenesis of cholesteatoma based on clinical results of anterior tympanotomy.

A new conception of the pathogenesis of cholesteatoma is proposed based on clinical results of anterior tympanotomy, a procedure developed in order to prevent recurrence of cholesteatoma following retraction pocket formation after canal-up operation. In the cholesteatomatous ear, there is always a long, thick bony septum between the epitympanum and the supratubal recess. This septum is called the anterior attic bony plate, forming the tympanic diaphragm together with the tensor tympani mucosal fold. In anterior tympanotomy, this bony plate is removed finishing intact canal wall mastoidectomy, making a new ventilating route to the eustachian tube. With this technique, the rate of recurrence was reduced from 17 to 5%. Based on these results it is proposed that the real pathogenesis of cholesteatoma is not tubal dysfunction, but the osseous tympanic diaphragm.

Cholesteatoma↗
PubMed1989

[Effect of bite plane on electromyographic activity of masticatory muscles. 1. Muscle activity during tapping movement].

The purpose of this study is to examine the influence of the insertion of bite plane on masticatory muscle activity during tapping movement, and find out useful parameters for examination and diagnosis of stomatognathic dysfunction. The subjects in this study were twenty normal subjects with intact dentition and no signs of mandibular dysfunction as the control group, and twelve subjects with unilateral temporomandibular joint pain during jaw opening or closing movement as the patient group. Electromyographic activity in the bilateral anterior temporal and masseter muscles and mandibular movement using the Mandibular Kinesiograph were recorded simultaneously during tapping movement. The usefulness of the 61 items used in this study was evaluated. The results were summarized as follows: 1. In the patient group, a significant correlation between the jaw opening degree during tapping movement and the maximal jaw opening one without pain was recognized. 2. The total muscle activity in the patient group decreased significantly by the insertion of the bite plane. 3. Many subjects of the patient group showed a significant difference between the right and left activity of each muscle. 4. A significant difference between the two groups was found in the duration of muscle activity before and after Silent period, those coefficients of variation and the difference between those durations of the right and left muscle activity. This study suggests that the above factors are very useful parameters for examination and diagnosis of temporomandibular joint dysfunction.

Humans↗
PubMed1989

[Application of occlusal splint for the patient with temporomandibular joint dysfunction. An application of silane coupling treatment: a case report].

The bite plane therapy has been one of the most useful treatment methods for patients with temporomandibular joint (TMJ) dysfunction. But the bite plane usually causes esthetic and articulation disturbances and it is occasionally difficult to use during mastication. The authors have fabricated a new type of bite plane, named occlusal splints, which covers each side of the premolars and molars. The occlusal splint was constructed by a hard-resin for the occlusal part and cast clasps for the retentive part and these parts were adhered after a pre-treatment of metal by the use of a silane coupling agent (Silicoater system). The patient was a 35 year-old man, with a chief complaint of left side reciprocal TMJ clicking. The anterior repositioning type of bite plane was applied for the treatment with the diagnosis of anterior disk displacement with reduction. But he complained of esthetic and articulation disturbances especially during working and eating. After four months we fabricated an occlusal splint that can be used for a long period of time. The patient was satisfied to use this occlusal splint and no symptoms of TMJ dysfunction were found with this appliance. It is suggested that the occlusal splint consisting of a hard-resin and cast clasps is a useful appliance especially for the purpose of use during working and eating, and for evaluating the properness of mandibular position.

Adult↗
PubMed1989

[Relationship between orofaciocranial morphologic factors and electromyographic activities of the masticatory muscles].

The purpose of this study is to evaluate the relationship between orofaciocranial morphologic and functional factors. The lateral cephalograms of 10 normal subjects were taken and traced. The authors divided cephalometric parameters into linear and angular measurements. Electromyographic (EMG) activities were recorded from bilateral anterior temporal and masseter muscles during tapping movement. Then the total muscle activity of both muscles, and the masseter muscle activity ratio in the total muscle activity were measured. The correlation coefficients between cephalometric measurements and EMG parameters were analyzed. The results of this study are as follows: 1) The total muscle activity revealed positive correlation with all the linear measurements. Especially, the total muscle activity significantly correlated with the size of mandible, such as Co-Go and Go-Me. 2) The total muscle activity showed a tendency to increase when the angles among SN plane, FH plane, maxillary base plane and mandibular border plane became small, and when S-N-A and S-N-B became large. 3) There was no correlation between masseter muscle activity ratio and cranial morphologic measurments. But masseter muscle activity ratio correlated with tooth position and anteroposterior inclination of the anterior teeth. These results suggest that the consideration of the relationship between orofaciocranial morphologic factors and EMG parameters is necessary for examining the masticatory muscle activity.

Cephalometry↗
PubMed1988

The significance of stapedial reflex test in facial nerve paralysis.

The stapedial reflex of 30 patients with peripheral facial nerve paralysis was compared with the results of facial paralysis scores. The stapedial reflex was measured with an oto-reflex analyser, RS-06A. The stimulation frequencies in the stapedial reflex test were 500, 1,000 and 2,000 Hz for both ipsilateral and contralateral stimulation. The stapedial reflex test at 500 Hz for contralateral stimulation seemed to be useful for evaluating the degree of facial paralysis. With 500 Hz or 1,000 Hz contralateral stimulation, the stapedial reflex test seemed to be useful for predicting the prognosis for facial nerve paralysis. In these stimulations, cases with a positive reflex within 2 weeks showed complete recovery within 12 weeks, and cases with positive reflex within 4 weeks showed recovery within 24 weeks.

Adolescent↗
PubMed1988

Studies on amidotrizoate therapy in sudden deafness (1978-1987).

The therapeutic effects of amidotrizoate in 47 sudden deafness patients from 1978 to 1987 were studied. The therapeutic results were investigated in terms of each of four variables: time from onset, degree of hearing loss, type of audiogram, and vertigo. Results showed that patients who had no vertigo, and were treated within 1 week of onset had satisfactory results. The degree of hearing loss did not influence recovery, although, all those with total loss type according to audiogram remained unchanged. Twenty-four of 34 cases (71%) treated within 2 weeks showed either complete or marked recovery; this proportion was not much different from the results in our previous investigations.

Adolescent↗
PubMed1988

Effects of vanadate on EP and its distribution in guinea pig cochlea.

Effects of sigma-sodium vanadate on endocochlear d.c. potential (EP) and cochlear microphonic potential (CM) were examined and its distribution was observed by an X-ray microanalyzer in the guinea pig cochlea. The perilymphatic space was perfused with 1, 5, and 10 mM solutions of sodium vanadate, using a Harvard Microperfusion pump. By perfusing the scala vestibuli, EP and CM showed a rapid decrease. On the other hand, by perfusing the scala tympani, EP showed an overshoot at first, then a gradual decrease, while CM showed only a gradual decrease. The rates of decrease of EP and CM were dependent upon perfusion time and vanadate concentration. After the electrophysiological examinations, the specimen of the cochlea was observed by X-ray microanalyzer. An accumulation of vanadium was confirmed, especially in the stria vascularis and the hair cells. From the results obtained, the possibility of the responsibility of vanadate for a hypothetical sudden deafness originating in the stria vascularis was discussed.

Animals↗