Tatsuya Matsunami

Gap Junctions Mediate Glucose Transport Between GLUT1-Positive and -Negative Cells in the Spiral Limbus of the Rat Cochlea

To elucidate the role of the spiral limbus in glucose transport in the cochlea, we analyzed the expression and localization of GLUT1, connexin26, connexin30, and occludin in the spiral limbus of the rat cochlea. GLUT1 and occludin were detected in blood vessels. GLUT1, connexin26, connexin30, and occludin were also expressed in fibrocytes just basal to the supralimbal lining cells. Connexin26 and connexin30 were present among not only these GLUT1-positive fibrocytes but also GLUT1-negative fibrocytes. In vivo glucose imaging using 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-6-deoxyglucose (6-NBDG, MW 342) together with Evans Blue Albumin (EBA, MW 68,000) showed that 6-NBDG was rapidly distributed throughout the spiral limbus, whereas EBA was localized only in the vessels. Moreover, the gap junctional uncoupler heptanol inhibited the distribution of 6-NBDG. These findings suggest that gap junctions play an important role in glucose transport in the spiral limbus, i.e., that gap junctions mediate glucose transport from GLUT1-positive fibrocytes to GLUT1-negative fibrocytes in the spiral limbus.

Roles of gap junctions in glucose transport from glucose transporter 1-positive to -negative cells in the lateral wall of the rat cochlea

Despite the importance of glucose metabolism for auditory function, the mechanisms of glucose transport in the cochlea are not completely understood. We hypothesized that gap junctions mediate intercellular glucose transport in the cochlea in cooperation with facilitative glucose transporter 1 (GLUT1). Immunohistochemistry showed that GLUT1 and the tight junction protein occludin were expressed in blood vessels, and GLUT1, the gap junction proteins connexin26 and connexin30, and occludin were also present in strial basal cells in the lateral wall of the rat cochlea. Gap junctions were found among not only these GLUT1-positive strial basal cells but also GLUT1-negative fibrocytes in the spiral ligaments and strial intermediate cells. Glucose imaging using 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-6-deoxyglucose (6-NBDG, MW 342) together with Evans Blue Albumin (EBA, MW 68,000) showed that 6-NBDG was rapidly distributed throughout the stria vascularis and spiral ligament, whereas EBA was localized only in the vessels. The gap junctional uncouplers heptanol and carbenoxolone inhibited the distribution of 6-NBDG in the spiral ligament without decreasing the fluorescence of EBA in the blood vessels. These findings suggest that gap junctions mediate glucose transport from GLUT1-positive cells (strial basal cells) to GLUT1-negative cells (fibrocytes in the spiral ligament and strial intermediate cells) in the cochlea.

Epidermal cyst of the bony external auditory canal

A previously healthy 3-year-old boy was referred to our hospital because of a mass in the left external auditory canal. He had no complaint and his mother found the mass by chance. On physical examination, left otoscopy showed a white mass in the posterior canal wall (Fig 1A). The mass was smooth-surfaced with unclear borders. The right external auditory canal and both tympanic membranes were normal. Computed tomography scan showed a mass in the posterior wall of the bony external auditory canal, lateral to the tympanic membrane without erosion of the surrounding bony wall (Fig 1B). The middle ear was normal on radiographic examination. With the patient under general anesthesia, the mass was surgically removed via a retroauricular approach. It was ablated from the bony wall and skin, and successfully enucleated en bloc without rupture (Fig 1C). It was lateral to the annulus, and the bone of the external auditory canal was normal in appearance. The enucleated mass was round, firm, and 8 mm 7 mm 5 mm in size. The external auditory canal was packed for 1 week after surgery. The patient had

A Case of Otogenic Brain Abscess

A case of otogenic brain abscess, secondary to cholesteatoma, is reported.Early diagnosis is very important for the treatment of otogenic brain abscess, which is a life-threatening disease. Early diagnosis of this disease is often difficult, because of modification by antibiotics.A 62-year-old male with a longstanding history of chronic left otorrhea with severe headache and fever, was admitted to our hospital. He was diagnosed as having left cholesteatoma, but prolonged headache and high fever did not improve.Unfortunately, we could not detect otogenic brain abscess early in the diagnostic process because of the modification by antibiotics and a lack of recognition for otogenic complications. Six days after admission, brain CT demonstrated a well-encapsulated brain abscess in the left temporal lobe. Although conservative treatment was administered, the diameter of the brain abscess increased daily. There are two therapeutic approaches; one is ear surgery, followed by neurosurgical treatment; the other is intracranial surgery, followed by otogenic treatment, after the general condition of the patient has improved. We selected the latter one to treat our case. The abscess was surgically drained by a neurosurgeon because of the high possibility it would penetrate the cerebral ventricle. The shadow of the brain abscess on CT disappeared after surgical drainage, and the symptoms began to improve. After his general condition improved, removal of cholesteatoma was performed. Two months later, he continuoes to do well.We concluded that this approach was a very useful and reasonable treatment in our case.

A Case of a Huge Antrochoanal Polyp with Profound Mental Retardation.

In patients with severe mental retardation, special surgical treatment should be considered.A giant antrochoanal polyp in a 31-years-old man with severe mental retardation is reported. The polyp discovered accidentally after the patient began exhibiting snore and rhinorrhea, and after a few months observation weight loss due to dysphagia was noted. Surgical treatment without nasal tamponade was planned, since we were concerned that the patient would be unable to cooperate with the necessary postoperative treatment; embolization of a maxillary artery, functional endoscopic sinus surgery (FESS) and Argon Plasma Coagulation. Postoperatively, the patients symptoms and the radiological findings of his sinuses were improved.