Prevention is best way to avert hearing loss
Salvi tells "UB at Sunrise" audience research aims to restore hearing, prevent loss

By JENNIFER LEWANDOWSKI
Reporter Staff

The best way to prevent hearing loss is through prevention, Richard Salvi, co-director of the UB Center for Hearing and Deafness, told a recent "UB at Sunrise" audience.

"Prevention is the most important and easiest way," said Salvi, a professor of communicative disorders and sciences, noting that when individuals use a lawnmower or shoot a rifle, for example, the noise produced has the potential to damage hearing. Protective measures-such as wearing ear protectors-should be taken, he advised.

However, hearing loss often occurs as the result of other factors, such as aging, disease or medications, Salvi said. The focus of his research, and that of his UB colleagues, is on restoring hearing capabilities and preventing hearing loss from occurring.

Salvi explained to the audience how hearing loss occurs, and described some of the warning signs of hearing loss.

He said there are two types of sensory cells-the outer and inner hair cells-that are responsible for hearing.

"When these cells are lost, we lose our hearing," he said. Damage to the outer hair cells-which are not connected to the brain-will cause partial deafness, he said, while damage to the inner hair cells-which "transmit sound information into the brain"-can lead to profound hearing loss. "We don't hear with our ear, we hear with our brain," he noted.

As a result of damaged or destroyed sensory cells, several conditions can occur, Salvi said. High-frequency hearing loss; intolerance of loud noises; tinnitus, or ringing of the ears, which he believes may originate in the brain, and the inability to discriminate sounds all are signs of hearing loss.

And while a hearing aid may help some of the problems, Salvi and his colleagues are looking at more innovative ways to cope with and prevent hearing loss.

Leupeptin, a protease inhibitor, was shown to prevent hearing loss in a study done at UB on chinchillas exposed to loud noises, Salvi said. Leupeptin inhibits proteases called calpains, Salvi explained, which are responsible for breaking down protein inside the cell that can lead to the death of the cell. The ultimate goal, he said, would be to develop a pill form of leupeptin that could be taken by someone like a pilot to prevent hearing loss while flying.

Moreover, cancer patients who take carboplatin, one of the most common chemotherapy drugs, often suffer hair-cell loss and auditory-nerve-fiber damage, Salvi said.

"We have compounds now that can be potentially given to cancer patients to prevent hearing loss," he said, adding that while research is ongoing, it could be years before a workable "cure" materializes.

But the primary research focus of the Center for Hearing and Deafness is on regeneration of sensory cells, Salvi said. Researchers are working with chickens, which naturally regenerate hair cells when the ear is damaged, he said.

"The main question we are asking is, if the hair cells regenerate, does the bird's hearing completely recover or are there any hearing, anatomical or physiological deficits?" he asked. When the damage isn't so severe, Salvi said, the birds seem to recover most of their hearing capabilities. But in more traumatic cases, hearing is not recovered. He said researchers are trying to discover what drugs can be infused into the inner ear that will allow new hair cells to be produced, thus restoring some hearing capabilities.

"This is going to be a very difficult problem to solve because it involves some of the most complex problems in cell biology-some of the same problems that cancer researchers are working on," Salvi said.

In addition, molecular biologists at UB have identified more than 30 genes that play a role in hereditary hearing loss, he said. And scientists also are working on "neuroplasticity," or the way in which inner-ear damage will affect the way the central auditory system works.

"The central auditory brain may reorganize itself, adjusting the chemicals it makes in response to the amount of stimulation it gets from the inner ear," Salvi said. "This has important implications for future techniques of restoring hearing."

For more information on research being done by center researchers, visit the center's Web site at http://wings.buffalo.edu/faculty/research/chd/.