Featured Research

from universities, journals, and other organizations

UT Southwestern Researchers See Hope For Treating Blindness In Preemies

Date:
March 7, 2005
Source:
University Of Texas Southwestern Medical Center At Dallas
Summary:
Hoping to prevent blindness in premature babies, UT Southwestern Medical Center researchers have identified a protein that responds to oxygen levels in cells and tissues and also affects the developing eye.

UT Southwestern researchers have discovered that a particular protein involved in responding to low oxygen levels plays a major role in the developing eye. Dr. Joseph Garcia (right), assistant professor of internal medicine, and Dr. Kan Ding, postdoctoral fellow in internal medicine, studied the eyes of newborn mice lacking HIF-2α and found that they were blind by one month of age.
Credit: Photo courtesy of UT Southwestern Medical Center

DALLAS - Feb. 22, 2005 - Hoping to prevent blindness in premature babies, UT Southwestern Medical Center researchers have identified a protein that responds to oxygen levels in cells and tissues and also affects the developing eye.

Premature birth carries the risk of multiple disabilities, including retinopathy of prematurity, or ROP. ROP affects the retina, the part of the eye that detects light before it is trans-formed in the brain to an image. ROP babies have poor vision, and in many cases, go blind.

In a study to be published online and in the March issue of Investigative Ophthalmology and Visual Science, Dr. Joseph Garcia, assistant professor of internal medicine at UT Southwestern, and colleagues, have identified a protein in mice called HIF-2α, which is important in retina formation. Controlling this protein, which is also found in humans, may help doctors treat or even prevent ROP before it happens.

Dr. Garcia examined the eyes of mice genetically engineered to lack the HIF-2α gene. These mice could not make HIF-2α protein and had multiple visual defects associated with blindness. They were blind by 1 month of age.

"These mice initially behaved as if they were blind," Dr. Garcia said. "And indeed, when we examined them, we found they had severe retinopathy."

Physiological studies using light, conducted by Dr. David Birch, collaborating scientists from the Retina Foundation of the Southwest and adjunct professor of ophthalmology atUT Southwestern, determined how their eyes were failing. Photoreceptors were poorly developed throughout the periphery of the retina and the retina wasn't processing visual information. Additional investigation of the mice lacking HIF-2α revealed extensive malformation of the blood vessels in their eyes, leading to ischemia, or reduced blood flow.

HIF-2α belongs to a class of proteins called transcription factors, which turn specific genes in the cell nucleus on in response to signals from the environment. Genes activated by HIF-2α create proteins that help the cell respond to noxious stimuli. For HIF-2α, the stimulus is hypoxia, a condition in which oxygen levels are too low. While appropriate hypoxia is required for proper development in many cases, inappropriate or prolonged hypoxia can damage cells and tissues. HIF-2α acts on genes that help deal with the low oxygen environment by stimulating the production of antioxidant molecules and promoting blood and blood vessel formation to deliver much-needed oxygen.

Biochemical tests revealed that antioxidant genes turned on by HIF-2α were inefficiently activated when HIF-2α was missing. In addition, the gene for erythropoietin (Epo), essential for blood and blood vessel development, was also affected when HIF-2α was missing.

For premature babies, it's not the lack of HIF-2α but the hyperactivity of the protein that may influence the development of ROP, Dr. Garcia said.

Preemies often have difficulty breathing due to under-developed lungs and are housed in special incubators that contain a higher percentage of oxygen than found in normal air. Exposure to this artificial environment tricks their bodies into accepting the high concentration of oxygen as normal.

When they are healthy enough, preemies can leave their incubators and start breathing normally. Their bodies, however, accustomed to higher oxygen, perceive normal oxygen as too low, and their bodies set off the protective hypoxic response. In the retina, HIF-2α may be triggered inappropriately, Dr. Garcia suggested, and unnecessary blood vessels are created. "Finding a way to shut down HIF-2α in ROP babies could prevent blindness when they come back down to regular oxygen," he said.

Dr. Yu-Guang He, assistant professor of ophthalmology at UT Southwestern, sees ROP babies in his clinical practice. "Of preemies weighing less than 2.75 pounds, 50 percent will develop ROP, and of these, 10 percent develop the most severe type, which leads to blindness. Dr. Garcia's work reveals an important mechanism in the development of ROP, with potential to prevent this devastating ailment. It provides new hope for these babies," he said.

Previous studies showed that antioxidant enzymes are regulated by HIF-2α. Antioxidant enzymes are vitally important for protecting against oxygen radicals, the levels of which are high in ischemic tissues such as in the eyes of mice lacking HIF-2α, Dr. Garcia said.

"The ability of HIF-2α to control multiple essential genes may be required for proper eye development," he said. "Furthermore, there may be additional, and as of yet unidentified, HIF-2α controlled genes that also are important for eye development."

Other contributors to this research were Dr. Kan Ding, postdoctoral fellow in internal medicine at UT Southwestern, Dr. Marzia Scortegagna, former postdoctoral fellow in internal medicine, and Robyn Seaman, research assistant at the Retina Foundation of the Southwest.

The study was supported by the National Heart, Lung, and Blood Institute, the American Heart Association, the American Cancer Society, the National Institute of Mental Health, the National Eye Institute, the Donald W. Reynolds Foundation and the Foundation Fighting Blindness.


Story Source:

The above story is based on materials provided by University Of Texas Southwestern Medical Center At Dallas. Note: Materials may be edited for content and length.


Cite This Page:

University Of Texas Southwestern Medical Center At Dallas. "UT Southwestern Researchers See Hope For Treating Blindness In Preemies." ScienceDaily. ScienceDaily, 7 March 2005. <www.sciencedaily.com/releases/2005/02/050224111440.htm>.
University Of Texas Southwestern Medical Center At Dallas. (2005, March 7). UT Southwestern Researchers See Hope For Treating Blindness In Preemies. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2005/02/050224111440.htm
University Of Texas Southwestern Medical Center At Dallas. "UT Southwestern Researchers See Hope For Treating Blindness In Preemies." ScienceDaily. www.sciencedaily.com/releases/2005/02/050224111440.htm (accessed July 22, 2014).

Share This




More Health & Medicine News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

TheStreet (July 21, 2014) New research shows Gilead Science's drug Sovaldi helps in curing hepatitis C in those who suffer from HIV. In a medical study, the combination of Gilead's Hep C drug with anti-viral drug Ribavirin cured 76% of HIV-positive patients suffering from the most common hepatitis C strain. Hepatitis C and related complications have been a top cause of death in HIV-positive patients. Typical medication used to treat the disease, including interferon proteins, tended to react badly with HIV drugs. However, Sovaldi's %1,000-a-pill price tag could limit the number of patients able to access the treatment. TheStreet's Keris Lahiff reports from New York. Video provided by TheStreet
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. Video provided by Newsy
Powered by NewsLook.com
Tooth Plaque Provides Insight Into Diets Of Ancient People

Tooth Plaque Provides Insight Into Diets Of Ancient People

Newsy (July 19, 2014) Research on plaque from ancient teeth shows that our prehistoric ancestor's had a detailed understanding of plants long before developing agriculture. Video provided by Newsy
Powered by NewsLook.com
Contaminated Water Kills 3 Babies in South African Town

Contaminated Water Kills 3 Babies in South African Town

AFP (July 18, 2014) Contaminated water in South Africa's northwestern town of Bloemhof kills three babies and hospitalises over 500 people. The incident highlights growing fears over water safety in South Africa. Duration: 02:22 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins