Anatomy Shared Article Research

This blog exists for the Anatomy students at Tree of Life Christian School. We will be reading various scientific articles, summarizing our research, and then commenting on others' summaries. We hope to broaden our view of the current research surrounding the human body, and to help others see how truly amazing the design of the human body is.

Thursday, October 16, 2008

Now Hear This: New Research Aims to Restore Lost Hearing

Summary:

At fourteen months old, Peter Steyer’s life hung between life and death as he lay in a hospital bed. By injecting intravenous doses of streptomycin, an antibiotic, the doctors could save Peter’s life, but this lifesaving antibiotic could have lifelong side affects/consequences. Peter’s parents chose to give their son the antibiotic and he lived to tell about it; however Steyger suffered hearing loss, which he says has virtually affected every area of his life, even his career choice.

Now Steyger investigates hearing at Oregon Health and Science University in Portland. He says, “What I’m doing is explaining why I’m deaf,” referring to his research.

Steyger’s research deals with how drugs, such as streptomycin, enter into the body and kill hair cells, which are sensory cells in the inner ear that are crucial to hearing. All hair cells have a bundle of hairlike extensions that protrude out from the inner surface of the cochlea, which is a snail-shaped coil of tissue deep in the inner ear. What happens is sounds pass into the ear and their vibrations rumble the cochlear fluid, which then results in the back and forth movement of the hair cells. The cells then translate every back and forth motion into an electrical signal that travels through nerve fibers to the brain. In the brain these signals are decoded as hearing.

People are born with about 16,000 hair cells. During the normal aging process, some of these 16, 000 hair cells eventually wear out and die. Most cases of acquired loss are due to the death of hair cells, but deafness can also be a result of other cause, for example: glitches in nerves that connect from the ear to the brain.

Previously scientists have believed that peoples hair cells-and good hearing-are irreplaceable. However, now genetic research deals with stem cells and studies of the fragile architecture of the inner ear propose that replacing lost hair cells, which would restore hearing, may in fact be possible.

Although human hair cells do not grow back after they wear out and die, animal hair cells do grow back. Most vertebrates are capable of growing hair cells back after old ones die, but eventually all mammals lose this innate replacement plan.

Scientists have been investigating genes that participate in hair cell information such as: hair cell development prompting, eliminating, stem cells, and the capacity to regenerate hair cells. Another important factor in the ability of hair cells to function efficiently is the exact positioning of the cell.

So far scientists are investigating cures, but what people like Steyger, who lost their hearing due to life-saving antibiotics, need is prevention of the damage in the first place; not to say that all their investigations are useless, but the ideal discovery would be a way to prevent life-saving antibiotics from having this lifelong consequence/side affect. For people who have already lost their hearing to life-saving antibiotics it is too late for prevention obviously, but in the future it will be very useful.

The way ototoxic antibiotics kill hair cells is by leaching into the cochlear fluid from the blood, collecting the hair cells inside, and killing them with their high concentrations. Steyger says that it is uncertain as to how ototoxic drugs get inside the hair cells. Some scientists believe that the cells take up the drugs using endocytosis, but experiments have shown that endocytosis is not the only process used to take in the drugs, because it occurs too qucickly for endocytosis to be the only process present. One of Steyger’s experiments suggests that ototoxic drugs enter cells by way of ion channels.

By continuing to study and experiment with animals, scientists may by able to develop a drug that can be given prior to or with ototoxic drugs that would close ion channels, preventing the drugs from entering into, and killing the cells.


My Response:

I thought this article was interesting because I guess I never really thought about actually “restoring” hearing, or preventing it from being lost in the first place. I guess I thought it couldn’t be done and that’s why people who are hard of hearing use hearing aids. Also it is very unfortunate that many life-saving antibiotics are ototoxic, or hair cell killing, but life is more valuable than the ability to hear.

I think that it would be difficult to try and come up with a cure and then eventually a solution by experimenting on animals because scientists have already established that the way humans and animals hear, and how their hearing works is different. A certain solution that works to restore an animals hearing, may not be able to restore a humans hearing. I suppose that once they find a solution on animals hearing loss, it will help them further in their research pertaining to a solution for human hearing loss.

http://findarticles.com/p/articles/mi_m1200/is_20_169/ai_n16533041/pg_1?tag=artBody;col1

3 Comments:

Blogger Heather said...

I had never thought about vaccinations impairing a person's hearing, so it was interesting to read about that. I definitely agree with Hannah that life is more important than hearing. This summary has given me knowledge about hearing that I didn't know. It's interesting that researchers are trying to find a "cure" for loss of hearing or a prevention for it, but I don't know that they ever will.

Thursday, October 23, 2008 6:52:00 PM  
Anonymous Anonymous said...

I certainly agree with Hannah and Heather, life is much more important than hearing vs. deafness, but unfortunately the gift of life is slightly overshadowed by not being able to hear. I'm sure that was a tough decision for the parents, but I'm glad they decided to take the risk with the medicine anyway. It was really interesting to read how sound is translated into what we actually perceive as sound, though to know even more about it would be even more intriguing, I believe. I wonder if doctors will ever find a way prevent or reverse the damage done by streptomycin...?

Thursday, October 23, 2008 7:11:00 PM  
Anonymous Anonymous said...

As Hannah & Heather said, hearing is certainly important, but by no measure does it take precedent over a person's life. I imagine it was hard for the parents to make a decision on the medicine, but I'm glad they chose life over hearing, partially because their son aided in the research of the streptomycin and its side-effects (other obvious fact of preservation of the sanctity of life). It was neat to read how sound gets translated into what we actually hear, though it did make me curious for more knowledge on it. Hopefully doctors will one day figure out a way to reverse, if not avoid altogether the effects of the drug.

Thursday, October 23, 2008 7:46:00 PM  

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