Hearing loss in humans drinking tube well water with high levels of iron in arsenic-polluted area.

Well water for drinking with increased levels of iron in arsenic-polluted areas has been reported worldwide. Oral exposure to arsenic has been shown to be associated with hearing loss, while there is no evidence for an association between excessive exposure to iron and hearing loss in humans. In this study, we determined iron and arsenic levels in biological samples and hearing levels by pure tone audiometry (PTA) in subjects in a control area and an arsenic-polluted area in Bangladesh.

cVEMP correlated with imbalance in a mouse model of vestibular disorder.

Background: Cervical vestibular evoked myogenic potential (cVEMP) testing is a strong tool that enables objective determination of balance functions in humans. However, it remains unknown whether cVEMP correctly expresses vestibular disorder in mice.

Objective: In this study, correlations of cVEMP with scores for balance-related behavior tests including rotarod, beam, and air-righting reflex tests were determined in ICR mice with vestibular disorder induced by 3,3'-iminodipropiontrile (IDPN) as a mouse model of vestibular disorder.

Improvement of balance in young adults by a sound component at 100 Hz in music.

About 80% of young people use personal listening devices (PLDs) including MP3 players to listen to music, which consists of sound components with various frequencies. Previous studies showed that exposure to noise of high intensities affected balance in humans. However, there is no information about a frequency-dependent effect of sound components in music from a PLD on balance in young people.

Manganese in toenails is associated with hearing loss at high frequencies in humans.

Purpose: Elevated hearing thresholds from high frequencies are known to be one of the hallmarks of age-related hearing loss. Our recent study showed accumulation of manganese (Mn) in inner ears resulting in acceleration of age-related hearing loss in mice orally exposed to Mn. However, there is no evidence showing an association between Mn in non-invasive biological samples and hearing loss in humans evaluated by pure tone audiometry (PTA).

Increased expression level of Hsp70 in the inner ears of mice by exposure to low frequency noise.

Previous studies showed that people in urban areas are possibly exposed to 60-110 dB of low frequency noise (LFN) defined as noise of ≤100 Hz in their daily life. Previous studies also showed increased health risks by exposure to high levels (130-140 dB) of LFN in animals. However, little is known about the health effects of exposure to an ordinary level of LFN.

[Development of Preventive Therapy by Clarification of Mechanisms of Environmental-Factor-Mediated Diseases].

Environmental factors affecting human health are generally classified into physical, chemical and biological factors. In this review article, we focus on ultraviolet (UV) as a physical factor, heavy metals as a chemical factor and Japanese cedar pollens as a biological factor. Since we believe that progress based on both fieldwork research and experimental research is essential in hygiene study, we included the results of both the research approached.

Hearing impairments caused by genetic and environmental factors.

Impairments of hearing and balance are major problems in the field of occupational and environmental health. Such impairments have previously been reported to be caused by genetic and environmental factors. However, their mechanisms have not been fully clarified.

Exposure to low-dose barium by drinking water causes hearing loss in mice.

Purpose: We continuously ingest barium as a general element by drinking water and foods in our daily life. Exposure to high-dose barium (>100mg/kg/day) has been shown to cause physiological impairments. Direct administration of barium to inner ears by vascular perfusion has been shown to cause physiological impairments in inner ears.

Chronic exposure to low frequency noise at moderate levels causes impaired balance in mice.

We are routinely exposed to low frequency noise (LFN; below 0.5 kHz) at moderate levels of 60-70 dB sound pressure level (SPL) generated from various sources in occupational and daily environments. LFN has been reported to affect balance in humans.

c-Ret-mediated hearing losses.

About 120 million people worldwide suffer from congenital (early-onset) hearing loss. Thirty percent of them have syndromic hearing loss and the remaining 70% have non-syndromic hearing loss. In addition, a large number of elderly people worldwide suffer from age-related (late-onset) hearing loss.

[Ultraviolet irradiation-mediated malignant melanoma induction with RET tyrosine kinase activation].

We previously established a RET-transgenic mouse line (304/B6), in which skin melanosis, benign melanocytic tumors and malignant melanoma spontaneously develop. We found that the activities of RET tyrosine kinase, Erk and c-Jun are definitely upregulated in malignant melanoma in the RET-transgenic mice of line 304/B6. We also established another RET-transgenic mouse line (192), in which skin melanosis and benign melanocytic tumors, but not malignant melanoma, spontaneously develop.