Working to help people with traumatic brain injury from left are Drs. Gang Wu,  Vladimir Berka,  and Ah-Lim Tsai,  of UTHealth, and Dr. James Tour,  of Rice University. (CREDIT: Rice University)
Working to help people with traumatic brain injury from left are Drs. Gang Wu, Vladimir Berka, and Ah-Lim Tsai, of UTHealth, and Dr. James Tour, of Rice University. (CREDIT: Rice University)

Ever heard the expression too much of a good thing? That applies to the body’s response to serious head injuries too.

When your brain is injured, your body sends extra oxygen to O2 – deprived areas. The problem is that this extra oxygen can make a bad situation worse. Its byproducts – reactive oxygen species (ROS) including superoxide free radical – contribute to oxidative stress.

Dr. Ah-Lim Tsai, professor of internal medicine, is working on a tiny solution for this big issue associated with traumatic brain injury or TBI. In 2010, TBI was linked to about 2.5 million emergency department visits, hospitalizations or deaths in the United States, reports the Centers for Disease Control and Prevention.

Tsai’s solution involves particles measured in billionths of a meter designed to neutralize the superoxide free radicals. Appropriately called antioxidants, they are comprised of polyethylene glycol-hydrophilic carbon clusters or PEG-HCCs and are produced at Rice University.

Tsai and his collaborators – Rice University chemist Dr. James Tour and Baylor College of Medicine neurologist Dr. Thomas Kent – reported in the Proceedings of the National Academy of Sciences that PEG-HCCs mitigated the effects of overoxidation in a test.

Not limited to the treatment of people with head trauma, Tsai believes these nanoparticles could also be of benefit to people suffering stroke, reperfusion injury, diabetes or cancer.

The researchers used an electron paramagnetic resonance spectroscopy technique that gets direct structure and rate information for superoxide radicals by counting unpaired electrons in the presence or absence of PEG-HCC’s antioxidants. Parallel assays with oxygen-sensing electrode and a peroxidase plus red dye confirmed the particles’ ability to catalyze superoxide conversion to oxygen and hydrogen peroxide.

An individual PEG-HCC nanoparticle catalyzed the conversion of 20,000 to a million superoxide molecules per second rivaling the activity of human Cu/Zn superoxide dismutase. “The next step in the research is to elucidate the detailed reaction mechanism of this non-metal, non-protein antioxidant catalyst,” Tsai said.

“PEG-HCCs have enormous capacity to convert superoxide to oxygen and the ability to quench reactive intermediates while not affecting nitric oxide molecules that are beneficial in normal amounts,” Kent said. “So they hold a unique place in our potential armamentarium against a range of diseases that involve loss of oxygen and damaging levels of free radicals.”

Dr. Vladimir Berka, senior research scientist at UTHealth, was one of the co-lead authors of the study. Dr. Gang Wu, an instructor in Tsai’s group also participated in this study.

Tsai is a professor in the Division of Hematology at McGovern Medical School and member of The University of Texas Graduate School of Biomedical Sciences at Houston. He is also an adjunct faculty member of Department of Biochemistry and Cell Biology at Rice University.

-Rob Cahill, Office of Public Affairs
This article includes information from a Rice University news release.