Noriyuki Yanagita

Risk factors for sudden deafness: a case-control study

In order to investigate risk factors for idiopathic sudden sensorineural hearing loss (sudden deafness), a case-control study was done in 109 patients with sudden deafness who visited our hospital between 1992 and 1994, with 109 controls matched to each patient by gender and age. Odds ratio (OR) and 95% confidence interval (CI) for smoking habits, drinking habits, dietary habits, environmental noise, past history of disease, sleeping hours, appetite, fatigue, incidence of common cold were obtained. Fatigue (OR: 3.28; 95% CI: 1.36-7.90) and loss of appetite (OR: 8:00; 95% CI: 1.00-64.0) elevated the risk for sudden deafness. Those who ate many fresh vegetables were at a decreased risk (OR: 0.48; 95% CI: 0.24-0.96 for light-colored vegetables, OR: 0.55; 95% CI: 0.30-1.02 for green-yellow vegetables). Personal histories of hypertension and thyroid disease, and susceptibility to colds appeared to be positively associated with the risk (0.05 < P < 0.10). Smoking habits, drinking habits and environmental noise had no significant association with sudden deafness. These results suggested that environmental factors, including diet, may be importantly involved in the genesis of sudden deafness.

The effect of furosemide on evoked otoacoustic emissions in guinea pigs

After recording transiently evoked otoacoustic emissions (TEOAEs) to a click stimulus in guinea pigs by using the IL088 which was developed by Bray and Kemp (1987) for easy recording and analysis of TEOAE, the changes after intravenous administration of furosemide (30 mg/kg or 50 mg/kg) were examined. The wave of the TEOAE could be detected from 20 of 24 ears (83%). After the i.v. injection of furosemide (30 mg/kg), TEOAE powers (total echo power and highest peak power in FFT pictures) decreased quickly and showed minimum values after 5-10 min. Then they increased rapidly and recovered normally within 60 min after injection. However, no ears showed TEOAEs during the 5- to 10-min period following the injection of the 50-mg/kg dose of furosemide. They then recovered slowly as compared with the group treated with the lower dose of furosemide (30 mg/kg). These changes are similar to those of the endocochlear potential (EP) after furosemide injection. These data support the notion that the EP can contribute to the mechanism of TEOAE generation.

A substrain of NZB mouse as an animal model of autoimmune inner ear disease

A substrain of an autoimmune-prone mouse, NZB/kl, was found to show spontaneous elevation of the auditory brainstem response (ABR) threshold with age. Morphological examination of the inner ear in NZB/kl mice with high ABR thresholds revealed pathological changes confined to the stria vascularis, including marked thickening of the capillary basement membrane which contained many foamy structures, and vacuolar degeneration of the intermediate cells. Circular or granular IgM deposits and some IgG deposits were found in the stria vascularis in the mice with high ABR thresholds, suggesting that deposits of immune complexes (mainly IgM antibodies) could cause strial damage that resulted in the ABR threshold elevation. Another substrain of NZB mice, NZB/san, showed lower levels of IgM immune complexes and anti-ss DNA antibodies, and did not develop either inner ear morphological changes or a high ABR threshold. NZB/kl mice may provide a useful animal model for studying the mechanism of autoimmune inner ear disease.

Soluble ICAM‐1 as a regulator of nasal allergic reaction under natural allergen provocation

Background: Intercellular adhesion molecule‐1 (ICAM‐1) plays a key role in the early stage of the signal cascade leading to cellular extravasation and the development of an inflammatory response. Recently, it has been reported that the soluble form of this adhesion molecule is present in human sera, possibly mediating biological actions.

Cell type-oriented differential modulatory actions of saikosaponin-d on growth responses and DNA fragmentation of lymphocytes triggered by receptor-mediated and receptor-bypassed pathways

We examined the immunoregulatory action of saikosaponin-d (SSd), which was isolated from the root of Bupleurum talcatum L. and had a steroid-like structure, on murine thymocytes, and compared the action with that on spleen cells. Constitutive DNA synthesis or the growth response stimulated with anti-CD3mAb of thymocytes were down-regulated by 3 micrograms/ml SSd, whereas with spleen cells these were up-regulated by the same concentration of SSd. On the other hand, 3 micrograms/ml of SSd greatly up-regulated the growth response and interleukin 2 (IL-2)/interleukin 4 (IL-4) production induced through a receptor-bypassed pathway by calcium ionophore A23187 plus phorbol 12-myristate 13-acetate (PMA) in thymocytes, whereas it only slightly up-regulated them in spleen cells. Moreover, the same concentration of SSd inhibited DNA fragmentation in thymocytes induced by A23187 or PMA. These results suggest a unique cell type-dependent immuno-modulatory action of SSd.

Factors affecting hearing results after stapes surgery

Factors affecting auditory improvement after stapes surgery were investigated retrospectively on a study group of 106 otosclerotic ears (86 subjects). While the closure of the air-bone (A-B) gap after surgery was good at 2 kHz and 4 kHz, it was poor at 8 kHz and at frequencies lower than 1 kHz. Under 1 kHz, the lower the frequency, the worse the A-B gap after surgery. Stapedotomy and partial stapedectomy showed better post-operative hearing gain at 4 kHz than total stapedectomy. Total stapedectomy scored significantly better at 250 Hz and 500 Hz than stapedotomy. There was a close relationship between the pre-operative and post-operative A-B gap at frequencies under 1 kHz. The smaller the pre-operative A-B gap, the better the closure of the post-operative A-B gap at these frequencies. It was speculated that otosclerotic ears with a larger pre-operative airbone gap might have another lesion in the middle ear other than the oval window.

Auditory and Vestibular Disorders Due to Barotrauma

In order to investigate auditory and vestibular disorders caused by barotrauma, 12 guinea pigs were exposed to compression and decompression between 1 absolute pressure (ATA) and 2 ATA in a pressure chamber. During the atmospheric pressure change spontaneous nystagmus occurred in two thirds of the animals. Auditory dysfunction that showed the difference between the right and left ears was confirmed by auditory brain stem response and Preyers reflex in the animals with spontaneous nystagmus. Damage to the organ of Corti was the most significant cause for the auditory dysfunction. Though findings attributed to the rupture of the round window membrane were recognized in four ears, the rupture or hemorrhage of the round window membrane was not the direct cause of the auditory dysfunction. The significance of the round window membrane rupture is discussed.

Blood flow in the cochlea, vestibular apparatus and facial nerve

Blood flow in the cochlea, vestibular apparatus and facial nerve was investigated in the 12 temporal bones of 6 guinea pigs using non-radioactive microspheres. The cochlear blood flow volume was 1.80 +/- 0.82 microliters/min and the blood flow volume of the vestibular apparatus was 0.43 +/- 0.16 microliters/min. The blood flow volume of the facial nerve in the temporal bone was 0.29 +/- 0.17 microliter/min. Regarding these blood flow volumes, the difference between the right and left was not significant, although there were large interanimal differences. The distribution of the blood flow in the cochlea, vestibular apparatus and facial nerve is also described.

Cochlear and renal pathology in the autoimmune strain mouse.

This study was designed to investigate the role of immunologic mechanisms in sensorineural hearing disorders and the relationship between inner ear and renal disorders. Autoimmune strain (NZB/kl) mice, in which autoimmune disease can be spontaneously induced, were used in this study. The mice were tested for acoustic brain stem responses, cochlear and renal disorders, and circulating immune complex serology by means of enzyme immunoassay. Pathologic studies consisted of observation of tissue changes following hematoxylin and eosin staining and indirect immunofluorescence staining under light microscopy. Compared to controls, the hearing was impaired in NZB/kl mice. Indirect fluorescence staining showed immunoglobulin G deposits in the stria vascularis. There was a correlation between the degree of hearing impairment and the severity of stria vascularis lesions. The NZB/kl mouse can provide a model for sensorineural hearing disorders secondary to immunologic disorders.

Estimated Annual Number of Patients Treated for Sensorineural Hearing Loss in Japan Results of a Nationwide Epidemiological Survey in 1987

We mailed questionnaires to 98 university hospitals and 939 hospitals with 200 beds or more throughout Japan asking for information on patients treated for sensorineural hearing loss between January 1 and December 31, 1987. The number of patients treated for sensorineural hearing loss in 1987 in Japan was estimated 13,900-19,600, ii) idiopathic bilateral progressive sensorineural hearing loss 13,900-19,600, ii) idiopathic bilateral progressive sensorineural hearing loss in 800-2,000, iii) perilymphatic fistula in 200-310, iv) mumps deafness in 200-400, and v) unilateral profound deafness in 2,000-3,000. Sex ratio (men over women) was 0.9 in sudden deafness and mumps deafness, 1.1 in idiopathic bilateral progressive sensorineural hearing loss and 1.5 in perilymphatic fistula. Patients were distributed with a definite peak from 50 to 59 years old in sudden deafness, from 30 to 39 years old in perilymphatic fistula, and two apparent peaks in teenagers and those aged 60-69 years in idiopathic bilateral progressive sensorineural hearing loss.