Tadashi Iwano

Quantitative immunocytochemical localization of Na+,K+-ATPase alpha-subunit in the lateral wall of rat cochlear duct.

Ultrastructural localization of the alpha-subunit of Na+,K+-ATPase on the lateral wall of rat cochlear duct was investigated quantitatively by the protein A-gold method, using affinity-purified antibody against the alpha-subunit of rat kidney Na+,K+-ATPase. In the stria vascularis, gold particles were sparse over the endolymphatic luminal surface of the marginal cells but were numerous over the basolateral membrane. The labeling density of the basolateral membrane was almost equal to that of the same domain of the distal tubule cells of kidney. The intermediate cells were studded with a large number of gold particles on the plasma membrane domain facing the basolateral domain of the marginal cells. On the luminal surfaces of the other epithelial cells, including those of Reissners membrane, no significant amount of gold particles was found. Many gold particles were localized on all the plasma membranes of the spiral prominence stromal cells and on the intracellular membrane domain of the external sulcus cells.

Otitis Media with Effusion and Eustachian Tube Dysfunction in Adults and Children

Eustachian tube (ET) function was studied in 162 ears with otitis media with effusion (OME) and chronic otitis media (COM), using tubo-tympanoaerodynamic graphy, patency and pressure equilibration test in the inflation-deflation test. Severe impairment of active opening function was found in both OME children and adults compared with that of COM patients. This impairment in active opening was thought to result from functional obstruction of the ET in 71.8% of OME children and 51.8% of OME adults. However, 45.6% of OME adults had an organic obstruction while such was present only in 28.2% of OME children. We deduce from this study that impaired active opening function of the ET in both OME children and adults is the result of functional obstruction rather than organic obstruction, but organic obstruction is considered to be related to the pathogenesis of OME in adults.

Quantitative immunogold localization of Na+,K(+)-ATPase alpha-subunit in the tympanic wall of rat cochlear duct.

Ultrastructural localization of Na+,K(+)-ATPase was quantitatively investigated in the tympanic wall of rat cochlear duct by use of the protein A-gold method, using an affinity-purified antibody against the alpha-subunit of rat kidney Na+,K(+)-ATPase. A moderate number of gold particles were found on the basolateral membrane of the interdental cells of the spiral limbus. A small number of gold particles were found on the basolateral surfaces of the border cells and Hensens cells. On the inner and outer sensory hair cells, however, the plasma membranes were rarely labeled by gold particles. The general pattern of labeling densities in cochlear structures determined here and in a previous communication from our laboratory shows good correlation with the distribution of Na+,K(+)-ATPase activity as previously estimated biochemically, cytochemically, and autoradiographically.

Tubal compliance — changes with age and in tubal malfunction

OBJECTIVE It is known that eustachian tubal compliance has influence on the tubal function. We applied the direct measurement method to ascertain whether or not aging and tubal diseases are related to the compliance of the cartilaginous part of the eustachian tube. METHODS We developed a method for directly measuring tubal compliance by inserting a balloon catheter, which is inflated with water, into the eustachian tube and comparing the change in balloon pressure with the balloon volume. This method is advantageous in that one can directly measure tubal compliance in the cartilaginous part of the eustachian tube. Using this method we examined tubal compliance in 16 normal young volunteer ears, 21 normal elderly volunteer ears, 11 elderly ears with patulous tube and 12 elderly ears with stenotic tube including otitis media with effusion. RESULTS In adults the tubal compliance increases in value with age. Tubal compliance of the elderly patulous tube was significantly higher than that of the normal elderly one, on the other hand the compliance of the elderly stenotic tube was significantly lower than that of the normal one. CONCLUSION Tubal compliance was considered to be changed with aging and influence of the patulous and stenotic tubes.

Quantitative immunoelectron microscopic localization of (Na+,K+)ATPase in rat parotid gland.

Distribution of (Na+,K+)ATPase on the cell membranes of acinar and duct cells of rat parotid gland was investigated quantitatively by immunoelectron microscopy using the post-embedding protein A-gold technique. In acinar cells, ATPase was localized predominantly on the basolateral plasma membranes. A small but significant amount of (Na+,K+)ATPase was, however, detected on the luminal plasma membranes, especially on the microvillar region of the acinar cells; the surface density on the luminal membrane was approximately one third of that on the basolateral membranes. In duct cells, many gold particles were found on the basolateral membrane, especially along the basal infoldings of the plasma membranes, whereas no significant gold particles were found on the luminal plasma membranes, suggesting unilateral distribution of ATPase in duct cells. We suggest that in acinar cells sodium ion is not only transported paracellularly but is also actively transported intracellularly into the luminal space by the (Na+,K+)ATPase located on the luminal plasma membranes, and that water is passively transported to the luminal space to form a plasma-like isotonic primary saliva, while in the duct cells the same ion is selectively re-absorbed intracellularly by (Na+,K+)ATPase found in abundance along the many infoldings of the basal plasma membranes, thus producing the hypotonic saliva.

Eustachian Tube Function Tests and their Diagnostic Potential in Normal and Diseased Ears

We have summarized various methods for testing Eustachian tube function since the 1980s. There have been numerous contributions to our knowledge on Eustachian tube and middle ear functions, and the pathophysiology of disorders of the middle ear has been clarified. Understanding of the Eustachian tube function and controlling the Eustachian tube dysfunction are mandatory for adequate clinical management and for improvement of the prognosis.

Active opening function of the human eustachian tube: comparison between sonotubometry and pressure equilibration test.

Sonotubometry and pressure equilibration test are representative test methods to evaluate the active opening capacity of the Eustachian tube. We applied these tests to 72 ears with otitis media with effusion and 21 ears with chronic otitis media. In 73 ears, both tests showed identical results (11 ears with good active function and 62 ears with poor function). Twenty ears showed good active opening by sonotubometry despite inability to relieve applied negative pressure by swallowing. This inconsistency is believed to result from a too short duration of the tubal opening, by which sound is transmitted through the Eustachian tube, without pressure change in the middle ear cavity. We propose that sonotubometry is a suitable method of detecting impairment of the tubal active opening function, but that a good result by sonotubometry does not always indicate a satisfactory pressure equilibration capacity of the Eustachian tube.

Direct Measurement of Eustachian Tube Compliance

We developed a method by which tubal compliance can be directly measured, and using this method we examined tubal compliance in 18 adults with a disease-free ear and 8 adults with chronic otitis media. This method is advantageous in that one can directly measure tubal compliance in the cartilaginous part of the eustachian tube. It is our view that each eustachian tube has its own compliance which is not influenced by mucosal swelling or muscle tension around the tube.

Sensation of Ear Fullness Caused by Eustachian Tube Dysfunctions

One hundred and ninety-four patients with a sensation of ear fullness were examined with the audiometry, tympanometry, and tubotympanoaero-dynamic graphy (TTAG) as a eustachian tube ventilatory test. In 74 cases of 194, the eustachian tube dysfunction was thought to cause an ear fullness sensation and patulous tube was found in 19 patients which is more frequent than expected. Functional unbalance of the both eustachian tubes which results from minimum ventilatory disturbance on the complaining side was also thought to be one of the causes of this symptom. The eustachian tube dysfunctions like stenotic or patulous tube could not be fully diagnosed by the audiometry and tympanometry because most patients with the eustachian tube dysfunctions showed normal middle ear pressure measured by the tympanometry. From our study, it could be concluded that eustachian ventilatory test like TTAG was very available in the patient with an ear fullness feeling which is one of the most common symptoms in the otolaryngological field.

Animal model of otitis media with effusion

A rat model of otitis media with effusion (OME) was developed by intratympanic injection of E. coli endotoxin and section of the third branch of the trigeminal nerve (V3). The period of fluid retention induced by the endotoxin was prolonged for 5 days or longer, in cases when tubal function was impaired by cutting of V3. Three Eustachian tube function tests (patency test of inflation-deflation tests, forced response test and negative pressure test) were carried out before and after the endotoxin inoculation and V3 sectioning. At 4 days after these procedures, passive opening pressure (Po), closing pressure (Pc) and tubal resistance (R2) were significantly lowered. The negative pressure test showed impaired capacity of active opening. This model of Eustachian tube dysfunction is considered to reveal functional obstruction, a condition similar to that of clinical cases of OME. The study shows that both inflammation in the middle ear and tubal dysfunction, such as functional obstruction, are factors in the development and prolongation of OME.