Featured Research

from universities, journals, and other organizations

Added Oxygen During Stroke Reduces Brain Tissue Damage

Date:
October 20, 2009
Source:
Ohio State University
Summary:
Scientists have countered findings of previous clinical trials by showing that giving supplemental oxygen to animals during a stroke can reduce damage to brain tissue surrounding the clot. The timing of the delivery of 100 percent oxygen -- either by mask or in a hyperbaric chamber -- is critical to achieving the benefit, however.

Scientists have countered findings of previous clinical trials by showing that giving supplemental oxygen to animals during a stroke can reduce damage to brain tissue surrounding the clot.

The timing of the delivery of 100 percent oxygen – either by mask or in a hyperbaric chamber – is critical to achieving the benefit, however.

"The use of supplemental oxygen after blood flow is restored in the brain appears to actually cause harm by unleashing free radicals," said Savita Khanna, assistant professor of surgery at Ohio State University and principal investigator of the research. "The resulting tissue damage was worse than stroke-affected tissue that received no treatment at all."

Previous clinical trials in humans have suggested that administering oxygen under pressure could harm stroke patients. But the studies did not take into account the status of blood flow in the brain at the time the oxygen was delivered, Khanna noted.

The types of stroke under study are ischemic, meaning a clot is blocking blood flow in the brain, rather than hemorrhagic, strokes that occur when blood vessels rupture in the brain.

The new Ohio State study showed that the use of pure oxygen that was delivered by mask during stroke was also effective, making for easier clinical application of such a therapy when the time for that is right.

However, technology doesn't yet allow for quick and continuous real-time measurement of blood flow in the brain in a hospital. This means clinicians treating stroke patients cannot risk administering hyperbaric oxygen that could do more harm than good if it is not timed properly.

"Hyperbaric oxygen during stroke shows the promise of being an effective tool, but there are things that need to occur before this can be applied in a clinical setting," said Cameron Rink, assistant professor of surgery at Ohio State and a co-investigator on the research. "We need to find better ways to monitor blood flow in humans in real time."

Rink presented the research October 19 during a poster session at the Society for Neuroscience annual meeting in Chicago.

Stroke is the third-leading cause of death in the United States, and an effective treatment remains elusive. So-called "clot-busting" drugs dissolve the clots, but typically must be administered within three hours of the stroke's onset. The average time between the start of a stroke and a patient's arrival at a hospital is about four hours – which adds to the treatment challenge, according to the researchers.

Khanna, Rink and colleagues tested the effects of supplemental oxygen therapy on five groups of rats in which the scientists induced a 90-minute ischemic stroke and then restored blood flow in the animals' brains.

Two groups of animals received either normal oxygen or pressurized oxygen while blood flow was blocked in the brain. Two other sets of rats received normal or pressurized oxygen after blood flow was restored. A control group received no supplemental oxygen, breathing room air instead.

Two days later, the researchers examined the rats' brains using powerful 4.7-Tesla magnetic resonance imaging to calculate the volume of damaged tissue. The images showed the size of the infarct, or the area of tissue susceptible to stroke damage as a result of poor oxygenation.

The images showed that the animals that received supplemental oxygen treatment while blood flow was blocked had a significantly smaller amount of tissue damage compared to the rats that received oxygen after blood flow was restored, Khanna said.

By further examining images of the rats' brains, the scientists determined that the supplemental oxygen during the active period of a stroke specifically reduced the death of neurons and prevented the damage that free radicals can cause to lipids that help protect those brain cells. By comparison, more dead neurons and oxidative stress were found in the brains of rats receiving oxygen only after blood flow was restored.

"Ultimately, the supplemental oxygen after blood flow is restored is more than the tissue can handle, and is more than it needs. Why add oxygen on top of tissue that's already oxygenated?" Rink said. "Supplemental oxygen during the blockage, on the other hand, is highly protective."

The researchers are using other technologies to determine how the loss of oxygen affects the functions of genes in the brain. Of the approximately 30,000 genes investigated to date, at least 6,000 are either inactivated or highly activated when a stroke reduces the oxygen in the brain. Their future work will explore the ramifications of those changed gene functions.


Story Source:

The above story is based on materials provided by Ohio State University. Note: Materials may be edited for content and length.


Cite This Page:

Ohio State University. "Added Oxygen During Stroke Reduces Brain Tissue Damage." ScienceDaily. ScienceDaily, 20 October 2009. <www.sciencedaily.com/releases/2009/10/091019172333.htm>.
Ohio State University. (2009, October 20). Added Oxygen During Stroke Reduces Brain Tissue Damage. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2009/10/091019172333.htm
Ohio State University. "Added Oxygen During Stroke Reduces Brain Tissue Damage." ScienceDaily. www.sciencedaily.com/releases/2009/10/091019172333.htm (accessed April 17, 2014).

Share This



More Mind & Brain News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Are School Dress Codes Too Strict?

Are School Dress Codes Too Strict?

AP (Apr. 16, 2014) Pushing the limits on style and self-expression is a rite of passage for teens and even younger kids. How far should schools go with their dress codes? The courts have sided with schools in an era when school safety is paramount. (April 16) Video provided by AP
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com
Couples Who Sleep Less Than An Inch Apart Might Be Happiest

Couples Who Sleep Less Than An Inch Apart Might Be Happiest

Newsy (Apr. 16, 2014) A new study by British researchers suggests couples' sleeping positions might reflect their happiness. Video provided by Newsy
Powered by NewsLook.com
Cognitive Function: Is It All Downhill From Age 24?

Cognitive Function: Is It All Downhill From Age 24?

Newsy (Apr. 15, 2014) A new study out of Canada says cognitive motor performance begins deteriorating around age 24. Video provided by Newsy
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