In a second group of rats, Zhu used microspheres, tiny balls of polystyrene labeled with radioactive isotopes, to assess blood flow. He injected the microspheres, which were just large enough to get stuck in the capillaries of the brain, into the rat's hearts. He then counted the number of microspheres in key brain regions to assess blood flow.
By matching a detailed inventory of physiological characteristics between the two groups of rats, including heart rate, blood pressure, pH and concentration of oxygen and carbon dioxide, Zhu could estimate brain blood flow in the group whose brain temperatures he had assessed. His results closely matched the predictions of Sukstankii's theory.
"Now that we know our theory is valid, we can use what we know about blood flow in various types of patients, calculate the characteristic length of this cold shield and make predictions on what the temperature distribution in the brain will be like," Yablonskiy says.
"We now also understand why attempts to use hypothermia for brain injury treatment in rats were encouraging," he adds. "Rats have quicker metabolism and higher blood flow, making their characteristic shielding length proportionally smaller. But the rat brain is already so much smaller that this still leaves room for cooling to penetrate throughout its brain."
Yablonskiy and colleagues including co-author Joseph J.H. Ackerman, Ph.D., the William Greenleaf Eliot Professor and chair of chemistry in the School of Arts and Sciences, have been developing a way to use magnetic resonance imaging units to assess temperature non-invasively in the human brain. Yablonskiy, Ackerman, who is also professor of radiology and research professor of chemistry in medicine, and their colleagues hope to apply this approach soon to further validate their theories.
Yablonskiy anticipates that his research group will have further opportunities to help fine-tune attempts tPage: 1 2 3 4 Related medicine news :1
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