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Science Forum Index » Medicine Forum » Carefully Killing Kids...
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| ironjustice... |
 Posted: Wed Jul 02, 2008 4:09 am |
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Source: UT Southwestern Medical Center
Resuscitation Technique After Brain Injury May Do More Harm than Good
The current standard practice of giving infants and children 100
percent oxygen to prevent brain damage caused by oxygen deprivation
may actually inflict additional harm, researchers at UT Southwestern
Medical Center have found.
UT Southwestern Medical Center
Dr. Steven Kernie (seated) led a team of researchers, including Dr.
Joshua Koch, which demonstrated that the current standard pediatric
practice of giving patients 100 percent oxygen to prevent brain damage
caused by oxygen deprivation may actually inflict additional harm.
Newswise — The current standard practice of giving infants and
children 100 percent oxygen to prevent brain damage caused by oxygen
deprivation may actually inflict additional harm, researchers at UT
Southwestern Medical Center have found.
Brain damage caused by oxygen deprivation, known as hypoxic-ischemic
brain injury, is one of the most common causes of death and long-term
neurological damage among infants and children. This can happen during
birth trauma, near drowning and other crises.
The UT Southwestern researchers found that mice treated with less than
a minute of 100 percent oxygen after a hypoxic-ischemic brain injury
suffered far greater rates of brain-cell death and coordination
problems similar to cerebral palsy than those allowed to recover with
room air.
“This study suggests 100 percent oxygen resuscitation may further
damage an already compromised brain,” said Dr. Steven Kernie,
associate professor of pediatrics and developmental biology and senior
author of the study, which appears in the July issue of the Journal of
Cerebral Blood Flow & Metabolism.
Most of the damage involved cells that create myelin, a fatty
substance that insulates nerve cells and allows them to transmit
electrical signals quickly and efficiently. Infants have much less
myelin than adults; as myelin develops in children they become more
coordinated. Areas of the brain with dense areas of myelin appear
white, hence the term “white matter.”
“Patients with white-matter injuries develop defects that often result
in cerebral palsy and motor deficits,” Dr. Kernie said.
Myelin comes from cells called glial cells, or glia, which reach out
and wrap part of their fatty membranes around the extensions of nerve
cells that pass electrical signals. The brain creates and renews its
population of glial cells from a pool of immature cells that can
develop into mature glia.
In their study, the researchers briefly deprived mice of oxygen, then
gave them either 100 percent oxygen or room air, which contains about
21 percent oxygen, 78 percent nitrogen and 1 percent other gases.
After 72 hours, mice given 100 percent oxygen fared worse than those
given room air. For example, they experienced a more disrupted pattern
of myelination and developed a motor deficit that mimicked cerebral
palsy.
The population of immature glial cells also diminished, suggesting
that the animals would have trouble replacing the myelin in the long
term.
“We wanted to determine whether recovery in 100 percent oxygen after
this sort of brain injury would exacerbate neuronal injury and impair
functional recovery, and in these animals, it did impair recovery,”
Dr. Kernie said. “Our research shows even brief exposure to 100
percent oxygen during resuscitation actually worsens white-matter
injuries.”
Dr. Kernie said adding pure oxygen to the damaged brain increases a
process called oxidative stress, caused by the formation of highly
reactive molecules. The researchers found, however, that administering
an antioxidant, which halts the harmful oxidation process, reversed
the damage in the mice given 100 percent oxygen.
“Further research is needed to determine the best possible
concentration of oxygen to use for optimal recovery and to limit
secondary brain injury,” Dr. Kernie said. “Research is now being done
to determine the best way to monitor this sort of brain damage in
humans so we can understand how it correlates to the mouse models.
There are many emerging noninvasive technologies that can monitor the
brain.”
Other UT Southwestern researchers involved in the study were Dr.
Joshua Koch, a pediatric clinical care fellow and lead author of the
study; Darryl Miles, a pediatric clinical instructor; Jennifer Gilley,
a student research assistant in pediatrics and developmental biology;
and Dr. Cui-Pang Yang, a postdoctoral researcher in pediatrics and
developmental biology.
The research was funded by the National Institutes of Health.
Visit http://www.utsouthwestern.org/neurosciences to learn more about
UT Southwestern’s clinical services in neuroscience.
Dr. Steven Kernie -- http://www.utsouthwestern.edu/findfac/professional/0,2356,13845,00.html
Dr. Darryl Miles -- http://www.utsouthwestern.edu/findfac/professional/0,2356,55956,00.html
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