Joseph A. Helpern, Ph.D., and his co-authors from New York University (NYU) School of Medicine were published in the peer reviewed international scientific journal, Nature Physics, published online March 6.

The paper describes a mathematical relationship between biological membrane permeability and how it affects the movement (diffusion) of water or other molecules that has gone unknown for more than 70 years. Helpern states that "knowledge about biological (cell) membrane permeability can help us understand how biological tissues function, when they are healthy, and more importantly when they are not, like in diseases such as cancer, stroke and multiple sclerosis, etc." It is thought that this new discovery will provide a new approach to studying diseases. The research for his publication began at NYU School of Medicine prior to Helpern joining the faculty at MUSC as vice chairman for radiology research, CoEE Endowed Chair in Brain Imaging and director of the new Center for Biomedical Imaging.

Helpern explained the significance of this work in a recent interview. "Membranes exist in most every material. To function properly, biological tissues (cells) depend on the properties of membranes. Membrane-like barriers also exist in other materials like porous media (oil shale, ceramics and cement) where their properties can be important for oil retention and material strength. One of the most fundamental properties of any membrane is its permeability (leakiness) to liquid substances like water. As a water molecule randomly moves around and bumps into a membrane, sometimes it passes through and sometimes it does not. Whether or not it does depends on the membrane permeability."

For years, no one had been able to figure out how to measure membrane permeability without disturbing or destroying the biological tissue (living organism) or porous media. "Since diffusion of molecules can be probed by either passing an electric current through the sample or by using magnetic resonance imaging, this new result makes possible, for the first time, the non-invasive measurement of membrane permeability," said Helpern. The mathematical relationship is derived by borrowing advanced theoretical techniques from an area of science called condensed matter physics.
Helpern and his colleagues are developing non-invasive imaging methods that will be used to diagnose diseases such as Alzheimer's disease, attention-deficit hyperactivity disorder, cancer and stroke. Visit http://dx.doi.org/10.1038/nphys1936.