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Biomedical subjects

M Amatsu

Publications and source records attributed to M Amatsu.

At least 55 records · Page 3Linked to original sources
PubMed1989

Effect of GABA (gamma-aminobutyric acid) on neurotransmission in inferior colliculus slices from the guinea pig.

Inferior colliculus (IC) slices from guinea pigs were prepared by cutting the IC parasagittally and incubating the obtained slices in the standard medium. Postsynaptic field potentials (PSFP) were recorded in the superficial layer of the pericentral nucleus (PN) by stimulating the deep layer of the PN. GABA (gamma-aminobutyric acid) and its agonists (muscimol and baclofen) and antagonist (bicuculline) were applied in the perfusion medium. GABA (1-12.5 mM), muscimol (1-200 microM) and (-)-baclofen (0.1-20 microM) reduced the amplitude of the PSFP in a dose-dependent manner. Bicuculline (1-10 microM) enhanced the amplitude of the PSFP and evoked the epileptiform burst discharge (EBD). The incubation of IC slices with methoxypyridoxin (100 microM) and 3-mercaptopropionic acid (100 microM) for 2 h reduced the GABA level of the slice to about 50% of the initial value, at which point a distinct EBD appeared. The application of GABA (5 mM) to the medium in this condition blocked the EBD completely. The removal of chloride from the medium as well as the application of furosemide (100 microM) enhanced the amplitude of the PSFP and also elicited the EBD; GABA application in this case did not block the EBD. These results indicate that GABA plays an inhibitory role in the IC, and that the reduction of GABA and the blockade of GABA function cause the appearance of EBD in the IC.

Action Potentials↗
PubMed1989

[Conservative treatment of Bell's palsy--high dose steroid infusion with low-molecular dextran].

The etiology of Bell's palsy has not been as yet completely elucidated and the treatment is empirical and controversial. The two most common forms of treatment are steroid therapy and surgery. On the basis of the pathophysiology of Bell's palsy that edema as well as primary or secondary ischemia lead to both compression and hypoxia, Stennert employed high doses of cortisone for a strong antiphlogistic and anti-edematous effect, and dextran in combination with pentoxifylline to increase peripheral nerve perfusion and reported high recovery rate. Since the past 3 years, we have been treating patients with Bell's palsy with a high dose of steroid plus low-molecular dextran (SD therapy). Hydrocortisone was added directly to 500 ml of dextran solution with ATP and vitamins, starting with 500 mg and finally down with 100mg during 7 days. Before we had adopted this regimen, the patients with Bell's palsy were treated with orally-administrated steroid. A half dose of steroid was administrated in the latter regimen. SD therapy was employed in 120 cases of Bell's palsy, and its results were compared with those of 82 cases with orally-administrated steroid. In a total of 67 cases with incomplete palsy, all cases obtained complete recovery within one month after the onset regardless of the mode of treatment. Each patients with complete palsy was examined with a nerve excitability test (NET) at the first visit and one week later. According to the response of NET, the patients with complete palsy were divided into the following three groups; "good", "poor" and "absent". In "good" group, all cases with SD therapy had complete recovery, while the recovery rate of 31 cases with orally-administrated steroid therapy was 90%. This difference was statistically significant (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1988

The clinical features and pathogenesis of myringitis granulosa.

Myringitis granulosa is not a rare pathologic condition of the tympanic membrane. However, the condition can be misdiagnosed as chronic suppurative otitis media, since intermittent purulent discharge is the commonest symptom in both disorders. Although the clinical features of myringitis granulosa have been well described by several authors, its pathogenesis is still obscure. In this study, 40 cases of myringitis granulosa were examined in detail to clarify the clinical features and the pathogenesis present. No drum perforations, no hearing impairments and normal X-ray findings indicated that myringitis granulosa had no relation to chronic suppurative otitis media. The other areas of the affected tympanic membrane, except for the site of granulation, showed such pathologic conditions as atrophy, clouding and calcifications. In these pathologic tympanic membranes, epithelial migration was disturbed to a high degree. We suggest that the granulation process on the tympanic membrane should be divided into two stages: (1) injury reaching the lamina propria of the tympanic membrane; and (2) disturbed epithelization of the tympanic membrane. The disturbance of epithelial migration of the tympanic membrane occurs with both stages.

Diagnosis, Differential↗
PubMed1988

Medical treatment of Bell's palsy. Oral vs. intravenous administration.

Infusion therapy using low-molecular dextran in combination with high-dose cortisone was modified from Stennert's original protocol and indicated in 50 cases of Bell's palsy. The effects of infusion were compared with the outcome in 36 cases treated by orally-administered steroids and vasodilators. In the case of incomplete palsy, the recovery rate was excellent regardless of the mode of treatment. If the palsy is not progressive, it is not necessary for patients with this condition to have infusion therapy. In the case of complete palsy, 95% of those with normal nerve excitability (NE) experienced complete recovery when treated by infusion. However, only 71% of this group experienced complete recovery when treated with oral administration. In the group with diminished or absent NE, complete recovery was obtained in 58% of the patients treated with infusion, whereas only 18% recovered completely when given oral administration. Thus, the recovery rate increased sharply in the case of infusion therapy. Therefore, the above-mentioned method of infusion therapy is indicated in cases of complete or progressively incomplete Bell's palsy except in those cases where its use is contra-indicated for some other reason.

Adenosine Triphosphate↗
PubMed1987

Discrepancies between clinical and histopathologic diagnoses in T3 pyriform sinus cancer.

The various ways in which pyriform sinus cancer extends to laryngeal structures were analyzed by whole-organ serial-sectioning. The problems regarding vocal cord fixation (T3) by this cancer are discussed. This study found that vocal cord fixation in pyriform sinus cancer is due mainly to the involvement of the intrinsic laryngeal muscles and not to the involvement of the arytenoid cartilage or the cricoarytenoid joint. A tumor originating in the medial wall tends to extend medially and to invade the intrinsic laryngeal muscles. This causes vocal cord fixation (T3) before classification as T2. However, a tumor originating in the lateral wall extends laterally beyond the thyroid ala (T4) with a mobile cord. Therefore, it is suggested that the T classification of the vocal cord fixation (T3) of pyriform sinus cancer may not reflect the actual cancer involvement.

Arytenoid Cartilage↗
PubMed1986

Epithelial migration on the tympanic membrane and external canal.

An ink dot staining method was used to examine epithelial migration in normal ears, in pathologic tympanic membranes, and in external auditory canal cholesteatoma. The direction of the epithelial migration was found to coincide with that of the vessels in normal ears. This suggested that epithelial migration was controlled by the vessels which supply the epidermal layer of the tympanic membrane. In pathologic tympanic membranes and external auditory canal cholesteatomas, epithelial migration was disturbed to various degrees and depended on the local conditions. In these pathologic conditions, the tympanic membrane showed less vascularization. Based on our findings, we believe that a poor blood supply is the major etiologic factor for the epithelial migratory disturbances of the tympanic membrane.

Cholesteatoma↗
PubMed1986

Pitch perturbation measures of voice production of laryngectomees after the Amatsu tracheoesophageal shunt operation.

Twenty tracheoesophageal speakers, 5 esophageal speakers, and 10 laryngeal speakers were subjected to pitch perturbation measurement in the sustained vowel production. Mean jitter, jitter ratio, average perturbation, and relative average perturbation were calculated from the successive vocal period. Jitter ratio values were 9.7 for laryngeal speakers, 29.6 for tracheoesophageal speakers, and 58.3 for esophageal speakers. Relative average perturbation values were 6.1 X 10(-3) for laryngeal speakers, 18.2 X 10(-3) for tracheoesophageal speakers, and 38.1 X 10(-3) for esophageal speakers. Results indicate that tracheoesophageal speech using exhaled pulmonary air is more stable than conventional esophageal speech.

Adult↗
PubMed1985

Stomal recurrence--etiologic factors and prevention.

Out of a total of 340 laryngectomies performed in the Department of Otorhinolaryngology at Kobe University Hospital from 1969 to 1982, there were 20 stomal recurrences. In the preoperative tracheostomy group, 6 out of 52 patients (11.5%) developed stomal recurrence compared to 14 out of 288 (4.9%) in the operative tracheostomy group. Of these 20 stomal recurrences, 7 were supraglottic with 1 subglottic extension, 9 were glottic with 8 subglottic extensions, and 4 were primary subglottic cancers. The mean interval between the laryngectomy and stomal recurrence was 16 months and ranged from 20 days to 55 months after laryngectomy. We analyzed our series together with recent material which had been subjected to pretracheal and paratracheal lymphatic dissection. Reports from the literature were also used. Tumor cell inoculation in the tracheostomy wound and persistent pretracheal and paratracheal lymph node lesion are the two most likely major etiologic factors. The above evaluation leads us to propose the following preventive measures: 1) thorough irrigation of the wound following the removal of the larynx, 2) complete excision of the tracheostomy tract for preoperatively tracheostomized patients, 3) pretracheal and paratracheal lymphatic dissection for subglottic lesion, 4) in the above cases, laryngectomy should be followed by peristomal radiotherapy.

Adult↗
PubMed1985

Primary tracheoesophageal shunt operation for postlaryngectomy voice restoration--a sphincter mechanism against aspiration.

Out of a total of 113 consecutive tracheoesophageal (TE) shunt operations for postlaryngectomy voice restoration in the past 8 years performed at the Department of Otorhinolaryngology, 92 patients (81%) succeeded in the postoperative TE speech. The essential part of this surgery consists of the construction of the TE shunt using the membraneous part of the trachea obtained at surgery. In the course of 8 years, important changes have been employed for the prevention of aspiration. We attempted to combine primary cancer surgery with the creation of intelligible voice, but without aspiration. For the above purpose, we have employed the bilateral esophageal muscle flaps (BEMF) against aspiration in combination with the TE shunt construction for phonation. Sixteen of 18 patients thus operated on complained of no aspiration even with a drop of saliva and dietary fluids. As far as the mechanism against aspiration is concerned, both dilatation and elevation of the cervical esophagus during deglutition, together with the BEMF, seem to approximate the sphincter mechanism against tracheal reflux. A proper case selection may achieve high success rates for preserving normal deglutition and restoring speech after total laryngectomy.

Adult↗
PubMed1984

Evaluation of speech of laryngectomees after the Amatsu tracheoesophageal shunt operation.

Fourteen patients were evaluated by a number of tests to analyze the voice produced following the senior author's surgical technique for speech rehabilitation. The parameters used were sustained duration of the prolonged vowel, counting per breath, syllables per breath, words per breath, and words per minute for quantitative determination. The qualitative parameters used were pronunciation accuracy, level of intelligibility and adequacy. The results obtained were better than those of esophageal speakers and approximate laryngeal voice. A comparison of relative advantage over other rehabilitative procedures is presented.

Aged↗
PubMed1980

A one stage surgical technique for postlaryngectomy voice rehabilitation.

A new one-stage surgical technique for postlaryngectomy speech was applied to 30 patients and its results are described. The essential part of this technique consists of the construction of a tracheoesophageal shunt using the posterior part of the trachea exposed at the time of the laryngectomy to reestablish an air communication between the trachea and the esophagus. Twenty-three of the 30 patients operated on developed conversational ability equivalent to that of a normal subject, except that they had to use a finger during speaking for the occlusion of the tracheal opening. The duration of phonation averaged 15 seconds. Speech developed in an average of 20 days after the operation was performed. Aspiration of liquids during deglutition was recognized in 9 patients. This was effectively controlled by digital pressure on the shunt during deglutition. The technique as described is applicable to nearly all candidates for total laryngectomy, with radical neck dissection and preoperative irradiation therapy.

Adult↗
PubMed1978

A new one-stage surgical technique for postlaryngectomy speech.

A new one-stage surgical technique for the postlaryngectomy speech applied to the 17 patients and its results are described herein. The essential part of this technique consists of the construction of a tracheo-esophageal shunt using only the remainder of the trachea obtained at the time of laryngectomy to reestablish an air communication between the trachea and the gullet. Fourteen patients of the 17 patients thus operated upon developed conversational abilities equivalent to the normal subject, except that they use a finger during the speech for the occlusion of the tracheal opening. This technique can be applied to almost all candidates for total laryngectomy with or without neck dissection. The initial speech was developed in 25 days after operation in average. The inflow of the salivas and/or fluids into trachea is not problematic in these patients. It has been well known that an air communication reestablished between the natural air way and the gullet could reproduce a vocal function after total laryngectomy [5]. Despite very few surgical techniques for this purpose have been described and applied clinically, although a tremendous effort has been made for the complete removal of the malignancy and the avoidance of recurrence up to the present [1--4, 6]. A new surgical method for achieving a tracheo-esophageal shunt for the postoperative vocal function is described herein.

Esophagus↗