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Biomedical subjects

J Okubo

Publications and source records attributed to J Okubo.

At least 19 recordsLinked to original sources
PubMed1992

[Exostosis of the external auditory canal and sensorineural hearing loss in professional divers].

Audiometric survey and endoscopic study of the external auditory canal were performed on a group of 31 professional divers, all of whom had experienced frequent exposure to dysbaric conditions. The results are as follows. 1) Over 40% had exostosis of the external auditory canal. There was no relationship between the incidence of the exostosis and the length of their occupational career as a diver. Many of the divers had hearing loss whether they had exostosis or not. 2) Over 70% had sensorineural hearing loss, taking into account hearing loss due to aging. Most had no experience of inner ear barotrauma on descent, causing sudden a shift in hearing threshold. Deafness was related to the length of their occupational career as a diver. In conclusion, we speculate that repetitive small changes in barometric pressure on the outer ear influences the pressure on the middle ear and further on that of the perilymph, finally damaging the inner ear auditory system.

Adult↗
PubMed1990

Aeration of the tympanomastoid cavity and the Eustachian tube.

Physiological changes in body position affect the degree of opening and closing of human auditory tubes. Notable changes were observed in lateral body position concerning the opening rate of the auditory tubes, which corresponds to the changes in pressure within the lower portion of the middle ear cavity. This physiological mechanism seems to be related with the anatomical direction of the auditory tube and the natural mechanism for the protection of the middle ear cavity. When a change takes place which moves the compliance of the eardrum to the positive side (e.g. head position change or static lateral body position), observation suggests the possibility of venostatis and production of gas. Measurement of the oxygen tension in the middle ear cavity under atmospheric pressure revealed the existence of constant gas production which maintains the pressure in the middle ear cavity at the same level as atmospheric pressure. This result denies the influx of gas from the atmospheric environment into the middle ear cavity. These results stem from the intrinsic physiologic mechanism of the middle ear cavity, namely maintenance of effective auditory sound conduction (a function to keep eardrum compliance as close to zero as possible), by keeping the pressure within the middle ear cavity below the atmospheric pressure, either at the same level as or slightly higher than that of the environment pressure. Gas emission from the middle ear cavity in the atmospheric environment and a low oxygen tension are a natural physiologic mechanism to protect the middle ear cavity from infection and other hazards.

Adult↗
PubMed1988

Physiology and pathophysiology of air-filled ear space and Eustachian tube function.

The function of the Eustachian tube under atmospheric pressure, on the grounds of our studies, is discussed as follows: (1) Criteria of natural valvular function of the auditory tube under a normal pressure environment. (2) Opening action of the Eustachian tube and mode of swallowing movement in comparison with soft palate movement. (3) High pressure environment and (opening action of) Eustachian tube. (4) Children undergoing tubing and their Eustachian tube function. (5) Ventilatory function of the Eustachian tube under normal pressure conditions. (6) Factors influencing changes in pressure in the tympanic cavity.

Adult↗
PubMed1988

Epidemiological studies on benign paroxysmal positional vertigo in Japan.

In 1980, the Research Committee of Peripheral Vestibular Disorders in Japan, which is supported by the Ministry of Health and Welfare, was founded by 24 members, from several districts in Japan. The Committee's first task was to draft the diagnostic criteria for several peripheral vestibular disorders, such as benign paroxysmal positional vertigo (BPPV), and vestibular neuronitis. For the national epidemiological survey, they then collected the data on 101 cases of BPPV out of some 783 vestibular disorder patients. In addition, data on 103 patients of BPPV out of 559 vestibular disorder patients were also collected from the Neuro-otological Clinic of the Toyama Medical and Pharmaceutical University Hospital. From these epidemiological surveys, the incidence of BPPV in Japan was estimated at 10.7 per 100,000 population, while that of BPPV in Toyama was estimated at 17.3 per 100,000 population. The ratio of BPPV was higher in female than male patients in both surveys. The age at the onset of BPPV peaked in the fourth decade in both males and females. Compared with the other epidemiological features of Meniere's disease and sudden deafness with vertigo in the same surveys, it appeared that the characteristic features of BPPV are epidemiologically similar to those of Meniere's disease, but different from those of sudden deafness.

Female↗
PubMed1987

Fibers supplying the laryngeal musculature in the cranial root of the rabbit accessory nerve: nucleus of origin, peripheral course, and innervated muscles.

The location of the rabbit laryngeal motoneurons whose axons traverse the cranial root of the accessory nerve was studied with injection of HRP or nuclear yellow into the laryngeal muscles in combination with the intracranial severing of either the rootlets of the vagus nerve or those of the cranial root. The motoneurons were located in the diffuse cell group that forms a subnucleus occupying the caudal two-thirds of the nucleus ambiguus and sending fibers to the inferior laryngeal nerve. The caudal one-third of the diffuse cell group supplying the lateral cricoarytenoid muscle, was occupied only by these motoneurons, whereas in its rostral two-thirds, they were intermingled with motoneurons having axons that traversed the vagal rootlets. The thyroarytenoid and posterior cricoarytenoid motoneurons are present in the rostral two-thirds of the diffuse cell group; axons of the former traversed the rootlets of the cranial root, and of the latter traversed the vagal rootlets. On the other hand, the medial scattered cell group, located in the rostral one-third of the nucleus ambiguus and sending fibers to the cricothyroid muscle via the superior laryngeal nerve, contained only motoneurons with axons traversing the vagal rootlets. The above findings clarified that fibers of the cranial root enter the inferior laryngeal nerve after joining the vagus, and then reach the adductor muscles for the vocal fold, with their neurons of origin in a caudal portion of the nucleus ambiguus. The vagal rootlet fibers, with their neurons of origin situated more rostrally in the nucleus, innervate the tensor and abductor muscles via the superior and inferior laryngeal nerve, respectively.

Accessory Nerve↗
PubMed1987

Localization of rabbit laryngeal motoneurons in the nucleus ambiguus.

The localization of rabbit laryngeal motoneurons in nucleus ambiguus was investigated using injection of a fluorescent labeling substance, i.e., nuclear yellow, into the individual laryngeal muscles. The nucleus ambiguus of the rabbit comprises four subnuclei, CoG, SGm, SGl, and DiG. The CoG is a group of compactly arranged neurons, and is situated in the rostral one-half of the nucleus. The SG, situated in its rostral one-third, is scattered around the CoG, with a subdivision into SGm and SGl. These subdivisions are medial and lateral to the CoG, respectively. The DiG is formed by diffusely arranged neurons, and is located in the caudal two-thirds of the nucleus. All labeled motoneurons were found in the ipsilateral nucleus ambiguus. The motoneurons supplying the cricothyroid muscle, which is innervated by the superior laryngeal nerve, were present in the SGm, with a clear rostralward segregation from the other motoneurons. The motoneurons supplying the muscles innervated by the inferior laryngeal nerve were located in the DiG, where they displayed a rostrocaudal myotopical arrangement in the order posterior cricoarytenoid, thyroarytenoid, and lateral cricoarytenoid. The posterior cricoarytenoid motoneurons were intermingled with the thyroarytenoid motoneurons in the rostral two-thirds of the DiG, and the former tended to be concentrated more rostrally than the latter. The lateral cricoarytenoid motoneurons were confined to the most caudal one-third of the DiG.

Animals↗
PubMed1987

Sonotubometric measurement of the eustachian tube function by means of band noise. A clinical view of the acoustic measurement of the eustachian tube.

The Eustachian tube is well known as an organ serving the ventilation and drainage of the tympanic cavity and mastoid. Ventilation is carried out by the opening and closing of the Eustachian tube accompanying swallowing movements. Until now there has been no instrument to quantify these motor activities of the tube necessary for its function as a ventilator. The author developed a generally applicable sonotubometer Model WIO-01 with the help of Siemens Hearing Institute K.K. for automatic measurement of the aforesaid tubal function with the use of 7 kHz full-octave band noise. In a sonotubometric trial with 32 adult female subjects, the duration of patency of the Eustachian tube was 288.5 +/- 1.38.5 ms, and the amplitude eliciting response was 16.4 +/- 8.3 dB. The positive response rate was 89.1%. In 89 children aged 4-12 years, a positive response was detected in 117 ears (61.9%). The mean duration of patency was 337.7 +/- 154.4 ms, and the amplitude 16.3 +/- 7.2 dB. It is physiological to have tubal opening and closing during natural swallowing. It is therefore important to understand the tubal function when dealing with tympanoplasty and diseases caused by tubal dysfunction.

Acoustic Stimulation↗
PubMed1987

[A study of eustachian tube function in fishermen (oikomi-gyohoh) divers].

The intranasal pressure at the opening of the auditory tube was compared by Valsalva's method with that of normal adults under atmospheric pressure to find the auditory tubal function of divers often exposed to hyperbaric conditions. It was found that the mean auditory tube opening pressure was higher in professional divers than in normal adults who had never been exposed to hyperbaric pressure. There are two ways of accommodating human auditory tubal ventilation: active opening and passive opening--the former is predominant in adults, the latter in children. The function of professional divers resembles the child type. This finding suggested that they were frequently exposed to a hyperbaric environment, and their auditory tube might not be opened and closed with each swallowing movement under atmospheric pressure, or the auditory tube and the middle ear themselves have been changed into a condition whereby they no longer needed the opening with each swallowing movement might under atmospheric pressure. Moreover, divers take various postures while they are diving, and in rapid dive, they often take a head-down posture. It was obvious that the auditory tube opens less readily in the head-down position. This phenomenon appears to represent the effect of hydrostatic venous pressure in water.

Adult↗
PubMed1986

An HRP study of the motoneurons supplying the rat hypobranchial muscles: central localization, peripheral axon course and soma size.

The locations of motoneurons (MNs) supplying the rat hypobranchial muscles (lingual, geniohyoid, and infrahyoid) and the peripheral courses of axons of these MNs were investigated by using a method of HRP injection into the hypoglossal nerve or these muscles in combination with severing of the hypoglossal and/or cervical components of the plexus hypoglossocervicalis. Moreover, some sizes of the MNs were investigated in both transverse and horizontal sections. The hypobranchial MNs formed a sequence of cell columns extending caudally from the hypoglossal nucleus, via the supraspinal nucleus, to the medial and then the ventrolateral subnuclei of the ventral horn of C1 to C3. The lingual and geniohyoid MNs were located in the hypoglossal nucleus. The majority of their axons passed solely through the hypoglossal nerve, whereas a small number of axons, whose somata lay in the caudal hypoglossal nucleus, passed through the first cervical nerve and then through the ansa cervicalis to reach the hypoglossal nerve. The infrahyoid MNs were located in the supraspinal nucleus and the ventral horn, and their axons passed through the first to third cervical nerves. The hypobranchial MNs were divided into three groups according to their size: the lingual, the geniohyoid and thyrohyoid, and lastly the other infrahyoid MNs, in order of smaller to larger size. The sizes of lingual, geniohyoid, and thyrohyoid MNs displayed a unimodal distribution both in transverse and horizontal sections, whereas the other infrahyoid MNs showed a bimodal distribution.

Animals↗
PubMed1986

The influence of eye movements and tactile information on postural sway in patients with peripheral vestibular lesions.

The statokinesigram of the 16 benign paroxysmal positional vertigo (BPPV) patients and the 28 vestibular deficits (VDS) patients were analyzed in comparison with the 20 normal subjects (NS). Velocity of the track (LNG/T), root mean square (RMS), and standard deviation area (SD-Area) were used as parameters. Fourteen different tests were done. When the result for each subject group were analyzed there were interesting differences between the compensated VDS and BPPV patients and between the untreated period and the compensated stage in each patient group. Comparing the data between NS and BPPV at the compensated stage, the latter group was unstable while watching LED with OKN on the tactile information plate (S-G plate). The significant differences were for RMS and SD-Area. The data of the NS and the untreated VDS show that the latter group was more unstable while watching LED with OKN than in the dark on the S-G plate. According to the data of the NS and the VDS at the compensated stage, the latter group was more unstable during OKN or watching LED which was almost the same as in the dark on both plate conditions. And it was more unstable while watching LED than during OKN on the S-G plate. The significant differences were for velocity of body sway (LNG/T). The neural region for compensation in BPPV patients might be on the visuo-oculomotor pathway through the peripheral retina. One of the most important regions for compensation in VDS patients might be in the rombencephalic reticular formation.

Eye Movements↗
PubMed1979

Epidemiological survey of definite cases of Meniere's disease collected by the seventeen members of the Meniere's Disease Research Committee of Japan in 1975--1976.

Between Aril 1975 and December 1976, the second nationwide survey of Meniere's disease in Japan was made by the 17 members of the Meniere's Disease Research Committee of Japan. The epidemiological data from 520 patients with definite Meniere's disease were analyzed in comparison with those from the 126 patients in the non-Meniere vertiginous group (Control A) and the 228 patients in the rhinolaryngological group (Control B). The male:female ratio of definite cases of Meniere's disease was almost the same, and the age distribution peaked at the age group of 40--49 years for males, while the peak for females was at the age group of 30--39 years. 5.8% of the 520 patients had a close relative who also suffered from Meniere's disease. From the epidemiological features, it may appear that the occurrence of vertiginous attacks in Meniere's disease is influenced much more by individual than by environmental factors. However, this feature can be considered as another evidence of the psychosomatic disorders involved in Meniere's disease.

Age Factors↗