There is currently only one treatment for stroke – a clot-busting drug known as tPA (tissue plasminogen activator). But it must be given within 4.5 hours of the onset of symptoms to be beneficial. As well, therapy can’t commence until after certain medical tests, including a brain scan, confirm the patient is suffering from an ischemic stroke caused by a clot that blocks blood flow to part of the brain. There is good reason to do these time-consuming precautionary tests; if tPA is given to patients with hemorrhagic strokes – or brain bleeds – it will kill them.
Less than 10 per cent of patients get tPA within 4.5 hours, at which point the brain can suffer permanent damage. As time passes, the loss of oxygen-rich blood sets in motion a chain of chemical reactions that produce toxic free radicals, which kill nerve cells.
The experimental drug – called Tat-NR2B9c – puts a halt to this destructive process.
“We’re blocking these reactions, and when you don’t get an accumulation of free radicals, the cells don’t die,” said Dr. Tymianski, who has been developing the drug for more than a decade.
His team’s study, published this week in the journal Nature, showed that the drug prevents brain cell death and preserves brain function in non-human primates.
Related Article: Added Oxygen During Stroke Reduces Brain Tissue Damage
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.”
Additional Research: Stopping stroke with extra oxygen: NetWellness
…The research showed the way that adding in extra oxygen helped. This discovery had to do with the normal brain molecule, glutamate. In stroke, this molecule is released in excess as the body’s attempt to keep the brain working.
The problem is that extra glutamate acts like a poison to nerve cells and causes damage. Adding more oxygen helps to convert the excess glutamate into much-needed energy for the cells. A special protective factor called “GOT” (glutamate oxaloacetate transaminase) facilitates the conversion of glutamate into fuel for the brain. GOT makes the system work even under conditions of lower oxygen so the brain doesn’t release too much toxic glutamate and damage the nerve cells.
This research, conducted at The Ohio State University Medical Center was funded by a pilot grant from The Ohio State Center for Clinical and Translational Science which is funded by the NIH to accelerate the process of turning scientific discovery into cures. This pilot award has added important information to explain how adding oxygen during stroke can reduce damage showing:
1) the right time frame for giving oxygen and
2) how oxygen converts toxic glutamate into fuel for brain cells
These two keys have opened the door for next steps and rapid translation to clinical research and treatment.
Originally posted 2012-03-20 13:59:37.
Robert July 4th, 2016
Posted In: Oxygen Health