Hyperbaric biomedical research probes new depths of understanding

See 3.2-ton hyperbaric chamber moved!

Tampa, FL (March 20, 2007) — USF Health recently became home to one of the country’s leading hyperbaric cell biology laboratories – where researchers are probing the effects of too much oxygen on the central nervous system (CNS).

Jay Dean, PhD, one of the world’s leading experts in hyperbaric neurophysiology, has attracted more than $4 million in external funding since 1997 from the National Institutes of Health, the Department of Defense, the Office of Naval Research (ONR), and private foundations. Dr. Dean, a professor in Molecular Pharmacology and Physiology, came to USF this summer from Wright State University, where he was the Brage Golding Distinguished Professor of Research. His research at USF continues to be funded by the NIH and soon the ONR Undersea Medicine Program, for a total of $1.2 million.

“The hyperbaric biomedical core research laboratory directed by Dr. Dean is second to none in the United States and a great asset for this University and this region,” said Abdul Rao, MD, MA, DPhil, senior associate vice president for USF Health and vice dean for research and graduate affairs at COM. “He joins our Interdisciplinary Signature Program in Neurosciences as a leader in his field, a very entrepreneurial faculty member, and a successful competitor for federal research funding. His team will work with existing faculty to advance our strategic efforts to continue to improve USF’s research capacity.”

Dr. Dean’s laboratory houses five different styles of pressure chambers, which mimic the environmental conditions challenging divers who breathe pure oxygen under high barometric (hyperbaric) pressure. As divers swim deeper the oxygen pressure in their lungs and blood increases along with outside water pressure. Breathing high-pressure oxygen for long periods increases the likelihood of CNS oxygen toxicity, which can ultimately result in grand mal type seizures. Besides affecting deep-sea divers, oxygen toxicity can be a severe complication for patients undergoing hyperbaric oxygen therapy for burns, non-healing wounds, acute gas embolism, certain infections and other conditions.

“Most people think of oxygen as a good thing, but too much oxygen for too long is actually dangerous to the brain, lungs and retina,” Dr. Dean said. “We’ve discovered that the brain cells that control breathing and blood pressure are extremely sensitive to excess oxygen. We’re investigating at the cellular level what makes these cells so sensitive to excess oxygen and why that stimulus is harmful.”

Such research may lead to the development of tools to predict which divers or patients are most vulnerable to CNS oxygen toxicity and prevent the onset of seizures. The researchers are also studying the neurophysiological effects of other gases such as nitrogen and carbon dioxide under varying pressures on brain cell function.

The researchers’ findings have implications for not only hyperbaric and diving medicine, but also for understanding how oxidative stress, in general, affects the neural control of respiration and cardiovascular function. Oxidative stress—an excess of renegade oxygen generated molecules called free radicals—can damage the body and induce neuron injury and death. Understanding the effects of oxidative stress on neurons regulating breathing has implications for understanding such disorders as sleep apnea and Sudden Infant Death Syndrome (SIDS).

Using fine-tipped electrodes inserted into thin slices of rat brain, Dr. Dean and his colleagues measure electrical impulses produced by single brain cells during their exposure to increasing levels of hyperbaric oxygen and observe how the brain cell functions change. In the past, the basic design of hyperbaric chambers hindered effective electrical recordings of brain cell activity because researchers had trouble quickly accessing the electrodes without disrupting carefully controlled gas pressures and temperatures inside the sealed chambers. But over the years Dr. Dean has worked with manufacturers on redesigns to improve recording stability.

“The design of our chambers lets us open or close them in about 20 seconds, so that the electrodes can be changed or manipulated as needed,” Dr. Dean said. “We can control physical stability inside the chamber and limit vibrations, which previously disrupted brain cell recordings.”

Dr. Dean is now adapting atomic force microscopy (AFM) to his most recently acquired 3.25 ton hyperbaric chamber. The use of hyperbaric AFM will enable Dean and his colleague, Dr. Dominic D’Agostino, to investigate the effects of hyperbaric gases on the physical properties of the cell membrane and other cellular structures.

Dr. Dean is writing a book on the physiology of high altitude flight during World War II, tentatively titled Aviator versus the Environment: Learning to Protect the Health of the High Altitude Aviator During WWII. His impressive collection of historical documents, books, films and other artifacts details the history of hypobaric and hyperbaric medicine and high-altitude flight. Dr. Dean became interested in the history of aviation medicine while working on his PhD in physiology at The Ohio State University. His interest was further stimulated by 15 years of living and working near Ohio’s Wright Patterson Air Force Base, which served as a military epicenter for the aviation medicine during WWII.

At 6,500 pounds, Dr. Dean’s newest hyperbaric chamber, shown here being transported to his lab, is the largest of five. It is designed to be used with an atomic force microscope and patch clamping apparatus to help researchers determine how gases and anesthetics with different lipid solubility affect brain cell function. The design, fabrication and installation of the chamber was supported by the Department of Defense and Office of Naval Research, Undersea Medicine Program.

“Hey, I thought you said this thing could turn on a dime!” Dr. Dean said during one particularly strenuous joint effort to maneuver the 3.2 ton chamber through the COM courtyard to the Hyperbaric Biomedical Research Lab. “I said it could FLATTEN a dime!” quipped Clayton Grable of Reimers Systems Inc, the company that designed and built the chamber.

Jay Dean, PhD, (top center) professor of Molecular Pharmacology and Physiology, poses in his lab with graduate students and staff who helped with the Big Move.

– USF Health –

USF Health is a partnership of the University of South Florida’s colleges of medicine, nursing, and public health; the schools of basic biomedical sciences and physical therapy & rehabilitation sciences; and the USF Physicians Group. It is a partnership dedicated to the promise of creating a new model of health and health care. One of the nation’s top 63 public research universities as designated by the Carnegie Foundation for the Advancement of Teaching, USF received more than $310 million in research contracts and grants last year. It is ranked by the National Science Foundation as one of the nation’s fastest growing universities for federal research and development expenditures.