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We previously discovered a splice variant of choline acetyltransferase (ChAT) mRNA, and designated the variant protein pChAT because of its preferential expression in peripheral neuronal structures. In this study, we examined the immunohistochemical localization of pChAT in rat cochlea and compared the distribution pattern to those of common ChAT (cChAT) and acetylcholinesterase. Some neuronal cell bodies and fibers in the spiral ganglia showed immunoreactivity for pChAT, predominantly the small spiral ganglion cells, indicating outer hair cell type II neurons. In contrast, cChAT- and acetylcholinesterase-positive structures were localized to fibers and not apparent in ganglion cells. After ablation of the cochlear nuclei, many pChAT-positive cochlear nerve fibers became clearly visible, whereas fibers immunopositive for cChAT and acetylcholine esterase disappeared. These results suggested that pChAT and cChAT are localized in different systems of the rat cochlea; pChAT in the afferent and cChAT in the efferent structures.

Patients with the contralateral type of delayed endolymphatic hydrops (DEH) may undergo an autoimmune attack against the other inner ear. As patients with unilateral juvenile deafness show no progression, despite lengthy observation, the autoantibody against the 68-kDa protein may be unrelated to the pathogenesis of DEH.The contralateral type of DEH is believed to have an autoimmune etiology, and sometimes develops from unilateral juvenile deafness. The purpose of this study was to determine whether autoantibodies are pathogenetically important in DEH.Sera from 9 patients with DEH, 18 patients with profound unilateral juvenile hearing loss and 15 control volunteer without inner ear diseases were investigated by means of Western blot assay against rat inner ear proteins.Among 8 patients with the contralateral type of DEH, 6 (75%) showed at least 1 reactive band on Western blotting. The protein that reacted most frequently had a molecular weight of 28 kDa, which was consistent with our previous results. Among 18 patients with unilateral juvenile deafness, 5 (28%) showed reactive bands, exclusively at 68 kDa.

We report a 48-year-old female with rhabdomyosarcoma in the maxillary sinus. She consulted our clinic with complaints of hemosputum and ophthalmalgia on the right side. Computed tomography and magnetic resonance imaging showed a well-enhanced mass in the superior-lateral portion of the right maxillay sinus with bone destruction of the orbital floor. Transantral biopsy of the tumor demonstrated embryonal rhabdomyosarcoma originating from the maxillary sinus. There was no evidence of metastases from rhabdomyosarcoma. The lesion was classified in group IIIA and stage II according to the Intergroup Rhabdomyosarcoma Study (IRS) classification, which is mostly used for pediatric cases. Treatment was performed according to the IRS IV protocol. She underwent chemotherapy with intravenous injection of vincristine, pirarubicin, cyclophosphamide, actinomycin D and ifosfamid, followed by surgical excision and radiotherapy (60Gy). There has been no evidence of local recurrence or distant metastasis 3 years post-operatively. Since rhabdomyosarcoma in adults is very rare, the standard treatment for the lesion has not been established. The present study suggested that chemotherapy combined with surgical excision and radiotherapy based on the Intergroup Rhabdomyosarcoma Study is also effective in the treatment of adult patients with rhabdomyosarcoma.

Endoscopic resection of nasal and paranasal sinus tumors is more aesthetic and less invasive than conventional resection, such as Luc's operation and lateral rhinotomy. We clarified the effect of radical endoscopic tumor excision and the control of local bleeding hazardous in endoscopic surgery. Subjects were patients with benign lesions in the nasal cavity, medial wall of the maxillary sinus, ethmoid sinus, and/or sphenoid sinus without concurrent malignant lesions. Although patients selection for malignant tumor excision was based on (1) possible en bloc resection, (2) low-grade malignant tumors, and (3) tumors in the nasal cavity and adjoining paranasal sinus, the final decision was made individual. Subjects were 23 patients with benign tumor (10 inverted papilloma, 9 hemangioma, 2 juvenile angiofibroma, and 2 other tumors) and 4 with malignant tumor (olfactory neuroblastoma, acinic cell carcinoma, squamous cell carcinoma, and chondroid chordoma) in the nasal and paranasal sinus. The tumor was resected en bloc except for patients with inverted papilloma (2 cases) and chondroid chordoma. Recurrence in benign tumors was zero during a mean observation of 21 months. One with chondroid chordoma, however, suffered a recurrent lesion 7 months after the initial operation. The lesion was successfully salvaged by a similar endoscopic procedure and subsequently treated with electron beam irradiation. Preoperative arterial embolization, laser coagulation, and ligation of the sphenopalatine artery were very useful in reducing blood loss during surgery and maintaining a clear endoscopic view. In intraoperative bleeding volume, less than 100 ml of bleeding occurred during surgery in 23 of 27 patients. The endoscopic excision of benign lesions in the nasal and paranasal sinus is thus as effective as conventional radical surgery. Endoscopic removal of malignant lesions remains controversial because of the small number of patients and short postoperative observation.

We evaluated the effectiveness of two navigation systems with optical tracking in endoscopic sinus surgery (ESS). The Signa SP/i Intraoperative navigation system (General Electric Co., Intraoperative NS) is advantageous in acquiring both real time and high-resolution images during surgery, compared to conventional image-guided navigation (Stealth Station TREON, Medtronic Inc., IGNS) that rely entirely on preoperative three-dimensional images. We studied the following in 14 patients treated with intraoperative NS and 19 treated with IGNS: 1) additional time for navigation system implementation, 2) available instrumentations in ESS, and 3) navigation system accuracy. Navigation systems required additional time to prepare ESS. The time lapse from admittance to the operating room to ESS onset was measured in patients under both systems and controls undergoing ESS without any image guidance. Preparation of the intraoperative NS required an additional 52 min and IGNS required 17 min compared to the control group. Based on operative instruments, the intraoperative NS has some limitations arising from the application of a high magnetic field. Surgical instruments must not be attracted by the magnetic field in the operating room. So those used in our study were thoroughly examined and some remanufactured using MR safe materials. All instruments in ESS could be used in surgical guidance during surgery in the IGNS. Anatomic landmarks were accurately visualized using intraoperative NS and IGNS. Intraoperative NS renews the image during surgery, so surgeons could confirm the surgical outcome during ESS. Since the average distant error in both systems was between 1 mm and 2.5 mm, we confirmed that accuracy obtained with both navigation system was suitable for ESS completion. The intraoperative NS renewed the image during navigation. In conclusion, both navigation systems are sufficient for accurate image navigation in ESS, but navigation systems must be selected based on the individual case.

It is reported that the prognosis of relapse nasal lymphoma is invariably fatal, and high-dose chemotherapy using autologous peripheral blood stem cell transplantation (auto-PBSCT) has been established as an effective treatment for patients with relapsing aggressive non-Hodgkin’s lymphoma. We experienced a case with T-cell lymphoma in the nasal cavity that relapsed after the initial treatment consisting of chemotherapy and radiation therapy. We treated with high-dose chemotherapy and auto-PBSCT to the patient. The patient has been disease free without therapy for 30 months following auto-PBSCT. Our experience suggests that high-dose chemotherapy using auto-PBSCT may be one of effective treatment option for relapsed nasal T-cell lymphoma when conventional chemotherapy fails.

We evaluated the advantages and disadvantages of interventional magnetic resonance (IVMR) image-guided endoscopic endonasal surgery for several diseases. Twelve patients, including nine with paranasal mucoceles, one with recurrence of chronic sinusitis, one with maxillary cancer, and one with dysthyroid ophthalmopathy were endonasally operated on with IVMR image guidance from May 2000 to April 2002. When the anatomy was distorted by previous surgery and the surgeons felt difficulty in orientating the lesions endoscopically, the usefulness of IVMR image-guided endoscopic endonasal surgery was sufficiently recognized. The following disadvantages, however, were also pointed out. The images on real-time were rougher than the usual MR images. Additional time was necessary for us to set up equipment and instruments, unless the surgeon and the room-staffs were familiar with the system. Furthermore, each instrument must be individually manufactured, often by hand, involving expense to the companies and a small potential market. It is concluded that the system is useful as a surgical supporting device for endoscopic endonasal surgery; the intranasal marsupialization of complicated paranasal mucoceles and verification of the position of the orbital contents in particular.

Granular cell tumor (GCT) is a relatively uncommon soft tissue tumor first described by Abrikossoff in 1926. In this report, we present one case of granular cell tumor in the inferior auricular region. A 54-year-old female complained of left subaural mass and enbloc resection was performed. Histopathological features of the specimen included proliferation of large, polygonal cells with an eosinophilic granular cytoplasm in the dermis and subcutaneous tissue. Immunohistochemically, the tumor cells were positive for S-100 protein, and this tumor is thought to derive from Schwann's cell. The boundary between the tumorous and non-tumorous part was indistinct since the tumor cells invaded into adjacent connective tissue. The treatment of choice is radical resection with clear surgical margins. To rule out late recurrences, patients should be followed by annual physical examinations.

Peritonsillar abscess is the most common deep neck infection in adults. However, pediatric patients have a smaller anatomy and are often unable to cooperate with examination and treatment. This article describes two cases of peritonsillar abscess in children. The first patient (5-year-old boy) complained of sore throat and pyrexia. CT findings suggested a peritonsillar abscess. Emergent transoral drainage was performed under general anesthesia. He was discharged without any complications. The second patient (7-year-old boy) complained of pyrexia and sore thoat. In this case, we also performed the emergent drainage under general anesthesia because of the peritonsillar abscess. Early diagnosis and adequate treatment lead to a considerable decrease in this morbidity. Especially in the pediatric age group, abscess drainage such as surgery under general anesthesia is sometimes required.

We reported a patient with cavernous hemangioma of the internal auditory canal. A 47-year-old man demonstrated progressive hearing loss and facial palsy on the left hand side over 4 years. A small tumor was detected in his left internal auditory canal by magnetic resonance imaging (MRI). The lesion displayed iso-signal intensity in T1-weighted images, high signal intensity in T2-weight images, and positive Gadolinium enhancement. Under tentative diagnosis as neurinoma, the tumor was totally removed by the translabyrinthine approach. The red tumor had compressed the facial and cochlear nerves, and adhered to the vestibular nerve in the internal auditory canal. It was diagnosed as cavernous hemangioma by immunohistochemical examination. There has not been any sign of recurrent tumors, but hearing loss and left facial palsy persisted after surgery. A cavernous hemangioma of the internal auditory canal tends to manifest with progressive hearing loss and facial palsy based on a review of past reports.

Patients with sudden onset deafness usually show marked hearing restoration, but in patients with sudden onset total deafness or near total deafness full hearing is sometimes not recovered.Between 1978 and 2000, we treated 247 patients with sudden deafness at our hospital, of which 71 had total deafness or near total deafness at the initial visit. In this retrospective study we divided patients into two groups: a total or near total deafness group (TD group), and the others group (O group). An analysis of case reports gave the following findings:1) There were no significant differences in age, sex, or the number of days from disease onset to initial visit between the two groups.2) The incidence of sudden deafness patients with vestibular symptoms in the TD group was significantly higher than in the O group.3) In the TD group, the rate of complete recovery and marked improvement was significantly lower than that in the O group.4) The rate of complete recovery and marked improvement in the TD patients with vestibule symptoms was significantly lower compared to those with similar symptoms in the O group.5) Hearing prognosis in sudden deafness patients with Grade 4a at the initial visit was poorer compared to patients with other Grades. However, 43.5% of sudden deafness Grade 4b patients recovered to Grade 1.

The anti-diuretic hormone, vasopressin, has been shown to be important in regulating inner ear fluid. We report on the involvement between Meniere's disease and vasopressin. We designed an experiment to determine whether vasopressin directly affects the fluid level. We chronically infused this hormone in rats and examined them for morphological signs of endolymphatic hydrops. Vasopressin infusion significantly increased the scala media area by 5.9±7.1% (P

We report a rare case of intracranial complication originating from the frontal sinusitis. The patient was a 32 year-old-male who initially presented with a high fever and anumb feeling in his head. A sudden onset of right upper limb dyskinesia appeared several days after the initial symptoms. Magnetic resonance imaging (MRI) was useful to reveal an epidural abscess in the frontal region of the head and a subdural abscess near the falx cerebri. These Lesions ware considered to arise from the direct extension of the frontal sinusitis via a posterior wall defect of the frontal sinus, and phlebitis of the diploic vein around the frontal sinus. The intracranial abscess and frontal sinusitis ware eliminated using Neurosurgical and Otolaryngological techniques.Even with the development of antibiotics, this condition can still be fatal; thus, we suggest that it is important to increase physician's awareness of this condition.

To clarify the clinical features of sudden deafness in the elderly, we investigated patients' profile and the prognosis of sudden deafness retrospectively. Of 224 patients with sudden deafness between 1978 and 1999, twenty-five patients more than 65 years of age were studied. The following results were obtained:1. The mean age of the patients was 70.8 years old, and there was no predominance in gender. The frequency of sudden deafness in the elderly has increased since 1998.2. Of 25 patients, 10 (40%) carried other systemic diseases at the onset of sudden deafness, such as diabetes mellitus, hypertension and liver dysfunction.3. The recovery of hearing loss in aged patients with sudden deafness was significantly worse than that in patients under 65 years of age.4. The aged patients tended to have various hearing losses in the contralateral ears. A poor prognosis of sudden deafness was noted in patients with hearing loss in the contralateral ear.

The endolymphatic-perilymphatic shunt operation between the scala media and scala tympani was performed in 22 guinea pigs with endolymphatic hydrops induced by the silver nitrate injection method 2 months before the operation. Two (n = 10), 7 (n = 6), and 28 (n = 6) days after the operation, the condition of the fistula and the inner ear pathology were studied histopathologically. In half of the animals, the fistula was open, whereas in the other half, the fistula was closed. In the group examined after 2 postoperative days, the animals with open fistulas showed a slight collapse of Reissner's membrane, which might indicate that excess endolymph escaped through the fistula into the scala tympani. In the groups examined later, especially in the group examined after 28 postoperative days, the animals showed distention of hydrops despite preservation of the fistula. Moderate-to-severe degenerative changes of the organ of Corti, macula sacculi, and stria vascularis were observed in the vicinity of the fistula. We conclude from this study that the endolymphatic-perilymphatic fistula created inside the cochlea apparently was not sufficient to reduce the hydrops. Rather, it caused degenerative changes of the inner ear structure. This type of surgery is not suitable for Meniere's disease.

212 patients diagnosed with sudden deafness between October, 1978 and April, 1998 were reported in our department. In order to clarify the relationship between sudden deafness and diabetes mellitus, the treatment course of 18 patients with sudden deafness, who were affected by diabetes, was analyzed retrospectively. The patients with sudden deafness were divided into two groups (diabetic and non-diabetic) and were analyzed. The following results were obtained:1) The mean age of patients in the diabetic group was 51.8 years, approximately 8 years older than the non-diabetic group. The number of patients with diabetes mellitus increased markedly in the last 10 years.2) There was no significant difference in hearing improvement after treatment as well as in hearing levels between the two groups.3) The rate of patients with dizziness or vertigo in the diabetic group was significantly higher than in the non-diabetic group. The patients with dizziness or vertigo showed a poorer prognosis in their hearing loss.4) There was no relationship between the duration of diabetes and the prognosis of hearing loss. The patients with retinopathy due to diabetes tended to show less hearing improvement.5) Steroid therapy for sudden deafness patients with diabetes was executed without worsening the diabetic condition if insulin was administered adequately.

We reported 10 patients with deafness due to mumps. The diagnosis was made according to the criteria for the diagnosis of mumps deafness determined by the Acute Profound Deafness Committee set up by the Ministry of Health and Welfare, Japan. We reviewed the clinical features and observed the following:1) The mean age of the patients was 18.1 years. The mean time of the onset of hearing loss was 6.1 days after the appearance of parotid swelling. All 10 cases had unilateral total or profound sensorineural hearing loss. Seven cases complained of dizziness.2) Nine cases were treated with steroid hormones, gamma globulin and vitamins. Hearing loss of eight cases did not improve, but one case recovered hearing in the low tone range. Dizziness disappeared in six cases, but in one case, dizziness persisted.3) In one case, delayed endolymphatic hydrops of the ipsilateral type was found 10 months after the onset of hearing loss due to mumps.

CATCH22 syndrome, as defined by D. I. Wilson, is associated with the following features: Cardiac anomalies, Abnormal facies, Thymic hypoplasia, Cleft palate, and Hypocalcemia resulting from microdeletions of chromosome 22q11. We encountered a patient with chronic otitis media, who was diagnosed as having CATCH22. We performed a right tympanoplasty and reported subsequent findings in this CATCH22 patient.The case was a 9-year-old female who complained of bilateral otorrhea. She was diagnosed with CATCH22 syndrome on the basis of clinical findings and a genetic analysis before visiting our clinic. Tympanoplasty revealed the handle of the malleus to be severely bent and ossicular movements seemed to be slightly restricted. Other anomalies were not observed. She was discharged without any further symptoms.

The atrial natriuretic peptide family (ANP family) is comprised of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP). These peptides regulate body fluid and blood pressure homeostasis as a neuropeptide in the central nervous system as well as a cardiac hormone in the periphery. To assess the possible physiological role of the ANP family, we investigated the immunohistochemical localization of these peptides in the rat inner ear. ANP-like and CNP-like immunoreactivities were observed in the spiral ligament just beneath the stria vascularis, spiral limbus, dark cell area, endolymphatic sac, spiral ganglion cells and vestibular ganglion cells. We could not detect specific BNP-like immunoreactivity in the inner ear. These observations were consistent with our previous study concerning the ANP family gene expression. The results suggest that the ANP family influences the metabolism of the inner ear fluid as well as afferent nerve activities in the inner ear.

We analyzed 14 patients who showed a further progression of hearing loss after an initial examination of 214 patients with sudden deafness. They were divided into 2 groups based on the type of hearing loss progression. Group I consisted of six patients who displayed a rapid progression after increased hearing loss had begun. Group II consisted of eight patients who showed transient hearing improvement before an increase in hearing loss. The clinical features of the 14 patients were from a earlier visit to the clinics experiencing dizziness and/or vertigo with less recovery of hearing loss than the other patients. However, more than 60% of the 14 patients showed complete recovery or a marked hearing improvement. The predominant type of hearing loss was high tone loss at the initial audiological assessment in both groups. The flat type hearing loss was usually noted at the time when the patients experienced their greatest hearing loss. Although the details of the etiology of hearing loss progression remain unclear, group I was thought to be the slow type sudden deafness, whereas the deterioration of hearing loss in group II may be due to a circulatory disturbance of the inner ear.

Vasoactive intestinal polypeptide (VIP) is a 28 amino acid peptide that was originally isolated from porcine duodenum. The presence of VIP has been demonstrated in the central nervous system and peripheral tissues. However, there have been few reports on VIP as a neurotransmitter, especially in the inner ear. To investigate the function of VIP in the rat inner ear, we examined the expression of VIP and the VIP receptor by immunohistochemistry. Using the anti-VIP and VIP receptor antibodies, scattered fibres in the cochlear nerve trunk demonstrating VIP-like immunoreactivity were found, and the spiral ganglion cells demonstrated ring-shaped VIP-like immunoreactivity. Immunoreactivity for the VIP receptor was predominantly found in the spiral ganglion cells. Our results suggest that VIP may play an important role as a possible neurotransmitter not only in the local control of cochlear blood flow, but also in the auditory system.

Between 1985 and 1995, 134 patients presented to our clinic with complaints of either dry mouth, decreased salivary flow or salivary gland swelling of unknown origin. These patients were diagnosed retrospectively based on the criteria established by the Sjögren's disease research committee (1977), and 30 patients were definitively diagnosed with Sjögren's disease while 23 were considered suspect. The gender distribution of these 30 patients was 25 female (83%) and 5 male (17%). The average patient age was 55.8 years for females and 42.6 years for males. Of 30 patients, 10 (33.3%) had only sicca syndrome and the other 20 (66.7%) had various complications such as collagen diseases, autoimmune diseases, and malignant lymphoid infiltration. Subjects included 14 cases of rheumatoid arthritis (RA), 1 case of systemic lupus erythematosus (SLE), 1 case of RA with periarteritis nodosa (PN), 1 case of progressive systemic sclerosis (PSS) with SLE, 1 case of PSS with Hashimoto disease, 1 case of malignant lymphoma and 1 case of RA with Waldenström's macroglobulinemia. Positive blood tests showed a relatively high incidence of elevated erythrocyte sedimentation ratios (ESR) (75%), elevated IgG levels (69.2%), positive anti-nuclear antibody (52.3%), positive anti SS A antibody (75%) and positive anti-SS B antibody (50%).

The diagnostic criteria for bilateral involvement of Meniere's disease delineated in our previous study were used to evaluate patients' anxieties and doctors' impressions in 135 cases of Meniere's disease with bilateral fluctuant hearing loss. These patients tended to have anxieties about disruption of their daily activities and their doctors tended to have the impression that their response to the therapy with diuretics, steroids or hospitalization was poor. Thus, the early diagnosis of bilaterality of the disease and intensive treatment such as sac op-eration or drug therapy is necessary.

Isosorbide (ISO) has proved to be one of the most effective agents in the appropriate period of administration for patients taking ISO, we have done follow-up interviews and examinations of 30 Meniere's cases (48 affected ears) for one year after they had taken ISO for at least half a year. Deterioration of clinical symptoms was found in 14 patients. Our observations indicate that patients who experience vertigo attacks during the initial 6-month treatment period and have good hearing (less than 40dB) in their affected ears should continue long-term treatment with ISO.

The anti-diuretic hormone vasopressin has been shown to be important in regulating inner ear fluid. The diuretic hormone, CNP, and its receptor, ANP-B receptor, may also function in the regulation of inner ear fluid. To determine whether vasopressin directly affects the fluid level, we infused this hormone to rat and assay of V2-AVP receptor mRNA by semiquantitative RT-PCR demonstrated a significantly lower level of this transcript in vasopressin-infused animals than in saline-infused animals. The levels of CNP and ANP-B receptors mRNA, however, were the same in both groups of rats. Results suggest that high plasma levels of vasopressin may be a principal causal factor of endolymphatic hydrops in Meniere's disease, perhaps by down-regulating the number of vasopressin receptors.

Although mechanisms regulating inner ear fluid have not been yet elucidated, control of blood flow has been thought to be of great importance. Vasoactive intestinal polypeptide (VIP) was the first neuropeptide demonstrated in cerebrovascular nerves. To study the possible role of VIP in regulation of inner ear fluid, we investigated the presence of mRNA for VIP and VIP receptor in the rat inner ear using a reverse transcription-polymerase chain reaction (RT-PCR) method. A single band of the size expected for VIP and its receptor was detected in mRNA from the rat inner ear by using primers specific for VIP and the receptor. The nucleotide sequences of the subcloned RT-PCR products were identical to those of rat VIP and the rat lung VIP receptor. These results indicate that both VIP and VIP receptor are expressed in the inner ear of the rat and suggest that VIP may be implicated in regulation of fluid in the inner ear.

Our department conducted an examination of the clinical characteristics of Menière's disease with bilateral fluctuant hearing loss, using data obtained in a survey involving sixteen institutes associated with the Vestibular Disorder Research Committee, Japan. A total of 480 cases were surveyed, of which 204 showed normal hearing in the second ear, and were thus classified as unilateral Menière's disease, or Menière's disease with unilateral involvement; 135 cases showed fluctuating cochlear symptoms in the second ear, and were therefore classified as Menière's disease with bilateral fluctuant hearing loss or bilateral involvement. Our results show that patients with bilateral involvement experience increased disruption of daily life activities, and respond poorly to therapy with diuretics or steroids. Hospitalization is often considered for these patients. For these reasons it is especially important that bilaterality be diagnosed as early as possible, and that intensive treatment be carried out. ENT specialists must recognize the seriousness of bilateral involvement, and take particular precautions against its occurrence.

INTRODUCTION Connexin26, a gap junction protein that spreads in the inner ear, is thought to be mainly responsible for nonsyndromic hereditary deafness. In the Caucasian population, 30delG is the most frequent mutation. 233delC is the most frequent, however, in the Japanese population. We studied 233delC mutations with restriction enzyme Apa I. SUBJECTS Subjects were 61 patients visiting the hospital between March 1997 and October 1999 suspected of hereditary deafness. All gave written informed consent for participation. METHODS Genomic DNA was extracted from peripheral blood cells and amplified by polymerase chain reaction (PCR) using 1 set of primers targeting the connexin26 gene (nucleotide--36 to 256). After ethanol precipitation, the PCR product was digested by restriction enzyme Apa I and analyzed through agarose gel electrophoresis. The wild gene is digested by Apa I and appeared to be shorter than the original PCR product, i.e., judged to be normal. RESULTS Three patients had 233delC mutations--1 homozygous and 2 heterozygous. These mutant alleles were confirmed to have 233delC mutations by direct sequence. CONCLUSIONS In targeting the mutation 233delC of the connexin 26 gene, restriction enzyme Apa I appears to be the most useful and economic method.

To assess the possible physiological role of the atrial natriuretic peptide (ANP) family, we investigated the expression of mRNA of ANP, brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), and their receptors in rat inner ear using the reverse transcription-polymerase chain reaction method. ANP and CNP message bands were detected in the inner ear, but the BNP message band was not. Amplification products of the expected sizes of ANP-A, ANP-B, and ANP-C receptors were detected in the inner ear. These results suggest that natriuretic peptide family may influence the function of the inner ear through the ANP-A, ANP-B, and ANP-C receptors.

The cause of endolymphatic hydrops, a characteristic finding in Meniere's disease, is not known. To study the possible involvement of the neurohormones vasopressin and oxytocin in this condition, we investigated whether transcripts of the genes encoding the arginine vasopressin (AVP) and oxytocin receptors are expressed in the rat inner ear. Utilizing the reverse transcription-polymerase chain reaction (RT-PCR) method, primers specific for each receptor showed a single message band of the expected size in the rat inner ear. When the PCR products were cloned, the sequences were identical to those of the real-type (V2) AVP receptor and oxytocin receptor transcripts. The finding of vasopressin and oxytocin receptor mRNAs in the inner ear suggests that these neurohypophyseal hormones may have roles in the regulation of inner ear fluid. In particular, the presence of vasopressin receptor mRNA in the inner ear supports the hypothesis of a relationship between high plasma vasopressin levels and endolymphatic hydrops.

C-Type natriuretic peptide (CNP) is the third member of the natriuretic peptide family which plays an important role in body fluid homeostasis. To determine a possible role of CNP in regulation of an inner ear fluid, we investigated the expression of CNP and atrial natriuretic peptide B receptor (ANP-B receptor) mRNAs in rat inner ear using a reverse transcription polymerase chain reaction (RT-PCR) method. Amplification products with sizes expected for CNP and ANP-B were detected in the inner ear. After cloning and analysis, the sequences for PCR products were identical to those of CNP or ANP-B receptor in the brain. These results indicate that both CNP and ANP-B receptor are expressed in the inner ear of the rat and suggest that CNP may play a role in inner ear function (such as regulation of inner ear fluid) in an autocrine and/or paracrine manner.