Mitsuaki Takahashi

Analysis of immunocompetent cells following inner ear immunostimulation

Immunohistochemical methods were used to investigate the development of inner ear immunocompetent cells in healthy, BALB/c mice over a 3‐week period as a result of a secondary inner ear response against keyhole limpet hemocyanin. Antibodies against murine macrophages and granulocytes (anti‐Mac‐1), T‐cells (anti‐Lyt‐1, anti‐Lyt‐2), and immunoglobulins (anti‐IgM, anti‐IgG, anti‐IgA) were used. Mac‐1 positive (Mac‐1   + ) cells were observed at 6 hours post‐challenge in the endolymphatic sac and cochlea and rapidly increased in both sites. Lyt‐1   + cells gradually increased in the endolymphatic sac after challenge, peaking at 2 and 3 weeks post‐challenge. In the cochlea, Lyt‐1   + cells were detected at 1 day post‐challenge and then increased. Lyt‐2   + cells were detectable in the endolymphatic sac and the cochlea by 3 weeks post‐challenge. The predominant immunoglobulin‐bearing cell in the endolymphatic sac was IgG, followed by IgM, with IgA seen late in the response. We conclude that the inner ear has the capacity to mount an immune response through the accumulation of the needed immunocompetent cells for antigen processing, antibody production, and modulation of the response through T‐helper and suppressor cell activity.

Anatomic distribution and localization of immunocompetent cells in normal mouse endolymphatic sac.

The distribution and anatomic localization of immunocompetent cells in normal mouse endolymphatic sac (ES) were examined by immunohistochemical methods. Antibodies against T cells (anti-Thy-1, -Lyt-1, -Lyt-2), macrophage (anti-Mac-1) and immunoglobulins (anti-IgM, -IgG, -IgA) were employed in an indirect technique utilizing strept-avidin-biotin complex. In the normal mouse ES, each of these cells could be detected by a difference in its frequency and distribution within and around the ES. Thy-1 positive (Thy-1+) cells are the most predominant in this tissue and can be seen throughout the ES. Lyt-1+ cells were found within the ES epithelium and in the perisaccular region, whereas Lyt-2+ cells were rarely present. Mac-1+ cells were present primarily in the lumen of the distal portion of the ES. IgM-bearing (IgM+) cells were seen in the subepithelial region, IgG+ cells were occasionally detected in the lumen and only a few IgA+ cells were present in the perisaccular region. This study revealed that the ES has the necessary immunological components for antigen processing and the generation of local immune responses within the inner ear.

Immunohistochemical Study of Murine Middle Ear and Eustachian Tube

The localization of the immunocompetent cells and secretory component (SC) of the middle ear and Eustachian tube (ET) was investigated in healthy, non-immunized BALB/c mice, using immunohistochemical methods. Utilizing specific antisera against murine cell associated antigens and SC, we investigated the distribution of macrophages and granulocytes (Mac-1+ cells), helper T cells (Lyt-1+ cells), suppressor/cytotoxic T cells (Lyt-2+ cells), immunoglobulin-bearing cells (IgA, IgG, IgM) and SC in the middle ear and ET. Mac-1+ cells were found to be the most predominant cell type, followed in descending order by Lyt-1+ cells, IgA+ cells, Lyt-2+ cells, IgG+ cells and IgM+ cells. Lyt-1+ cells were found in the lamina propria, whereas Lyt-2+ cells were detectable in the epithelium of the ET. SC was seen predominantly within the tubal and glandular epithelial cells. These findings suggest that the distribution of the immunocompetent cells and SC in the ET is similar to that seen in secretory immune sites elsewhere in the body.

Experimental Study on the Effects of Gentamicin Injection on the Guinea-pig: Electrophysiological Studies

The inner ear distortion induced by gentamicin (GM), a type of aminoglycoside antibiotic, was examined in guinea-pigs. Previous studies which investigated the function of the eighth cranial nerve and organ of Corti using cochlear microphonics (CM) and compound action potential (CAP) reported ototoxicity following experimental exposure to GM. In this report, the effects of GM on the cochlea and the eighth cranial nerve were investigated systematically by measuring CM, CAP, summating potentials induced by 90 dB (SPL) tone burst, endocochlear potential (EP) and K+ ion concentration of the endolymph. Guinea-pigs were treated with a daily intramuscular injection of GM (60 mg in 1.5 cc) at a dose of 60 mg/kg during different treatment periods. The maximum output voltage of AP was decreased by injection of GM (60 mg/kg x 24). A decrease in the CM maximum output voltage and the elevation of CM pseudothreshold were typically seen after GM injection at a test frequency of 8 kHz and a decrease in CAP was also observed. Changes in EP during 3 min anoxia were observed, in particular a decrease in the absolute value of the negative potential. The endolymph K+ ion concentration remained unchanged. These findings indicate that the diffusion potentials decreased at the same time as reduction of maximum output voltage in CM induced by GM injection.

Secretory Component and IgA in the Endolymphatic Sac

Immunohistochemical methods were used to investigate secretory component (SC) and immunoglobulin A within the inner ears of Sprague Dawley rats and BALB/c mice. Utilizing specific antisera against SC and IgA, the distribution and localization of SC and IgA were studied in normal, non-immunized ears of both animal species. The kinetics of SC and IgA were also investigated during a secondary immune response following keyhole limpet hemocyanin (KLH) challenge of murine inner ears. In the non-immunized murine inner ear, neither SC or IgA were found. In contrast, SC was localized within the epithelial cells and lumen of the endolymphatic sac (ES) in non-immunized rats and faint luminal IgA staining was seen in one-third of the animals, as well as an occasional IgA-bearing cell in the ES. In the inner ear secondary immune response, SC was found only within the endolymphatic sac of approximately 50% of the immunized mice 14 days after KLH challenge. IgA-bearing cells were also observed within the ES 2 to 3 weeks following KLH challenge. We conclude that there are species differences in the distribution of SC and IgA within the inner ear, and that under pathological conditions the endolymphatic sac may be a site of IgA and SC induction.

Regeneration of the damaged endolymphatic sac epithelium

The regeneration of endolymphatic sac (ES) epithelium after epithelial damage was examined using 5‐bromo‐2′‐deoxyuridine (BrdUrd). Guinea pigs and anti‐BrdUrd, antikeratin, and anti‐basement membrane (BM) component antibodies were used. Animals were sacrificed at 3, 7, and 14 days following an immune injury of the ES. The animals were sacrificed after an administration of BrdUrd at the designated times. Decalcified temporal bones were examined immunohistochemically. At day 3, epithelial loss without subepithelial BM was seen in the region of marked cell infiltration. BrdUrd‐positive cells could be detected in the epithelium at the edge of the wound. At day 7, cell infiltration decreased, and the epithelial lining with BM was repaired. These results reveal that the epithelium of the ES can regenerate within 7 days after an immune injury.

A case of tiger bite injury with unilateral internal jugular vein reconsruction

We reported a very rare case of tiger bite injury. The patient was a 57-year-old male who was a keeper at Asahiyama zoological park in Asahikawa city. He was attacked by an Amur tiger which seriously injured upper half of his body, including intracranial trauma. We performed an operation to save his life. There was severe bleeding from the cervical wound because the left internal jugular vein was severed, therefore, it was clamped and occluded with ligatures. We treated his many wounds, but the intracranial bleeding was not relieved. We considered that ascending intracranial pressure by occlusion of the left internal jugular vein caused the bleeding. Left internal jugular vein reconstruction was performed by neurosurgeons. They used an artificial graft initillay, and then used the greater saphenous vein as a graft. We considered the patients left internal vein as the dominant side.

Steroid-Responsive Sensorineural Hearing Loss in a Patient with Idiopathic Thrombocytopenic Purpura.

A 43-year-old female with steroid-responsive sensorineural hearing loss (SNHL) was described. She had been treated with steroids for idiopathic thrombocytopenic purpura (ITP) since 1981.The patient complained of sudden hearing loss and tinnitus in the left ear on the 9th of June, 1995, at which time, 2.5mg of prednisolone was administered for ITP. The audiogram showed SNHL of low frequency sounds. Immunological studies showed positive rheumatoid factor and antinuclear antibody, high levels of complement, immune complex, IgG and IgA.The patients hearing improved after initial treatment with 40mg of prednisolone. Fluctuations in hearing loss were observed with changes in the dose of prednisolone. The above clinical course suggested steroid-responsive SNHL.Steroid administration could be reduced with a supplemental administration of Saireito without any significant deterioration of hearing. Laboratory studies and the effect of steroids suggest a causative role in immune-mediated inner ear disorders.

A Case of an Esophageal Foreign Body Found by Chance in X-rays of the Neck.

This report describes a 59-year-old woman with a foreign body in the neck found by chance during an X-ray examination. The foreign body was discovered when she visited a neighbourhood hospital because of a heavy feeling in the posterior region of her neck. When she was referred to our hospital, this complaint had diminished, but surgical removal of the foreign body was conducted. A lateral neck incision revealed a 20 mm long wire, the tip of which was embedded in the esophageal wall. Following removal, the wire was shown to the patient, who indicated that she had not seen it before. We concluded that the foreign body had penetrated the wall of the esophagus when the woman was a child.