Cell and Gene
|
Our exquisite hearing system is realized by the motility of the outer hair cells (OHCs) in the cochlea, which amplifies the sound entering the ear. The origin of this OHC motility is believed to be a motor protein expressed in the plasma membrane of the OHCs. This motor protein has a diameter of one-thousandth of a hair width and is thought to transform its own size. In the laboratory, we are attempting to elucidate its transformation mechanism and to develop a new technology for manipulating this motor protein.
|
|---|
|
The motility of outer hair cells (OHCs) is thought to be based on the motor protein prestin. However, structure of prestin has not yet been clarified.
|
|
|---|---|
|
The lateral walls of the outer hair cells (OHCs) have been shown to be densely covered with particles about 10 nm in diameter, these particles being believed to be the motor protein prestin. However, since there are many kinds of intrinsic membrane proteins other than prestin in the plasma membranes of OHCs and CHO cells, it was impossible to clarify which structures observed in such membranes were prestin.
|
|
|
Recently, it has been found that the outer hair cells (OHCs) can be protected from traumatic noise exposure by prior sublethal conditioning with heat stress. However, the mechanisms of such protective effect have not yet been clarified.
|
|
Diagnostic Apparatus
|
In our laboratory, based on knowledge of mechanical engineering and auditory mechanics, we would like to contribute to the area of human health by developing unique and effective diagnostic systems. The middle ear, which transmits the sound entering the external ear to the inner ear, is difficult to directly observe and thus the diagnosis of middle ear diseases is difficult. Therefore, we are attempting to develop a non-invasive diagnostic system for such diseases. Furthermore, we are focused on applying this system to neonates for early detection of hearing dysfunction.
|
|---|
|
Hearing disorders are reported to occur in about 1-2 out of every 1,000 neonates. Early diagnosis and treatment of such disorders in neonates is highly effective for realization of linguistic competence and intellectual development. Current procedures used for hearing screening programs include otoacoustic emissions (OAEs) and automated auditory brainstem response (ABR). Their diagnostic sensitivities have been reported to be high. Unfortunately, however, it is impossible to diagnose the type of hearing loss such as conductive hearing loss and sensorineural hearing loss by these methods.
|
|
|---|
Simulation
|
Computer simulation is a useful method to analyze a phenomenon which is difficult to experimentally measure and to predict an unknown phenomenon from a known one. Our hearing system is extremely mechanical and shows tiny vibrating behavior of the nanometer level. We are developing finite element models of the mammalian hearing system and attempting to clarify the mechanism of sound perception. Furthermore, we are aiming to elucidate clinical issues such as hearing loss caused by traumatic noise exposure, ototoxic acid, diseases and so on.
|
|---|
|
As many as 12,000 sensory cells called outer hair cells exist in the mammalian inner ear. There are three rows of such cells, and they amplify the hearing sensitivity by several ten thousand times by moving in synchrony with the sound delivered in the inner ear． However, the effects of such coordinated movement on the cochlear amplification is unknown.
|
|
|---|