Science Daily: Structure of inner-ear protein is key to both hearing and inherited deafness

Thousands of microscopic hair cells located in the cochlea of the inner ear are extremely sensitive structures. Stereocilia are hair-like structures located on the hair cells and tip-links are filaments that connect the stereocilia in bundles. These structures are involved in the depolarization process, which ultimately leads to the excitation of the auditory nerve resulting in physiologic percept of sound.

ScienceDaily.com released an article on April 17, 2010 about new studies from the labs of David Corey, professor of neurobiology at Harvard Medical School and Howard Hughes Medical Institute investigator, and Rachelle Gaudet, associate professor of molecular and cellular biology at Harvard University's Faculty of Arts and Sciences. The group performed studies on one of two proteins, cadherin-23, that join to form each tip-link. Their studies show how mutations of the protein can make this otherwise extremely strong protein to weaken in its calcium bonding, resulting in inherited deafness. When weak, stress can cause this bond to "break in billionths of a second."

"Still image from a simulation that "stretches" the two end-most segments of the cadherin-23 protein, much as loud noise might do to its real-life counterpart in the inner ear. Such extreme stress can cause cadherin-23 to break in billionths of a second. (Credit: Marcos Sotomayor)"

Read the awesome article: Structure of inner-ear protein is key to both hearing and inherited deafness

via Science Daily

Link between Painkillers and Hearing Loss

Can taking common over-the-counter painkillers lead to hearing loss? The results of a study published last month in the American Journal of Medicine investigated this question. Participants included about 27,000 men who were tracked every 2 years for 18 years enrolled in the Health Professionals’ Follow-Up study. The data collected included medical information, use of analgesics, and hearing loss among other data.  

Acetaminophen

Researchers found that men below 50 years of age who regularly took acetaminophen (found in Tylenol) more than two times per week had about double the risk of hearing loss compared to men who did not take the medicine regularly.

Ibuprofen (main ingredient in Advil) and Non-Steroidal Anti-Inflammatory Drugs (NSAID)

Men younger than 60 years who regularly took ibuprofen and NSAID at least twice a week had almost two-thirds higher risk of hearing loss compared to men to took it less often.

For men younger than 50 years, the risk of hearing loss was higher by 33 percent using aspirin, 61 percent with use of NSAIDs and 99 percent with use of acetaminophen, compared to men of the same age who used these drugs less often (all based on taking painkillers twice a week). 

Why does this happen? According to one of the researchers, Dr. Sharon G. Curhan, of Channing Laboratory and Brigham and Women's Hospital mentions that high doses of painkillers are known to have a toxic effects on the ear leading to hearing loss and tinnitus or ringing in the ears.

A positive finding for men 60 years and older was that they did not show a greater risk for hearing loss when compared to the findings for younger men.

The take home message is that you should consult with your physician about the risks of taking over-the-counter or prescription medication. If you think you have a hearing problem, you can have your hearing tested by an audiologist. 

Via Yahoo! Health

Revisiting the Dancing Outer Hair Cell

Back in 2007, I posted a link to the video of a hair cell located in the cochlea, which is the sensory organ of hearing. I find the auditory system so fascinating, that I had to post it again.

A UK Scientist by the name of Jonathon Ashmore was able to isolate a single outer hair cell and make it dance! That's right, dance! Check out the dancing outer hair cell.

Read an explanation of movie from Ashmore's website here: http://www.physiol.ucl.ac.uk/ashmore/hairexpl.htm

Study published about genes that influence age-related hearing loss

A new study by House Ear Institute and other institutions, published in the journal Human Molecular Genetics, has found genes related to hearing loss risk. 

You can read more about this interesting study at the Los Angeles Times website:  http://latimesblogs.latimes.com/booster_shots/2008/12/gene-that-influ.html

Here is another news brief about the same study:

Science Daily