Physiology

Dr. Russell Witte, a native Tucsonan, received a BS degree with honors in physics from the University of Arizona in Tucson (1993). Following travel abroad in Europe and Brazil, he began graduate studies in bioengineering at Arizona State University. His doctoral thesis (PhD, 2002) used chronic microelectrode arrays to describe sensory coding and learning-induced plasticity in the mammalian brain. He then moved to the University of Michigan in Ann Arbor and, as a post doc in the Biomedical Ultrasonics Laboratory, developed novel hybrid imaging techniques that integrate ultrasound, light, and/or microwaves for medical applications. In 2007, Dr. Witte returned to Tucson and is now Associate Professor of Medical Imaging, Optical Sciences and Biomedical Engineering at the University of Arizona. Dr. Witte’s Experimental Ultrasound and Neural Imaging Laboratory (EUNIL) devises cutting-edge imaging technology, integrating light, ultrasound and microwaves to diagnose and treat diseases ranging from chronic tendon disorders (tendinopathies) and irregular cardiac rhythms (arrhythmias) to breast cancer. By integrating different forms of energy, special effects are created that enable ultrasound imaging of optical absorption deep in tissue (photoacoustic imaging), mapping current source densities in the beating heart (acoustoelectric imaging), and elasticity imaging of human muscle and tendon for quantifying tissue mechanical properties. Dr. Witte's research further extends into nanotechnology and smart contrast agents, which have applications to functional brain imaging, cardiovascular disease, and cancer. Dr. Witte works closely with collaborators in the Colleges of Engineering, Optical Sciences and Medicine, as well as industry, to develop cutting-edge imaging technologies that potentially improve patient care. Dr. Witte is also a member of the Arizona Cancer Center, Sarver Heart Center and School of Mind, Brain, and Behavior, as well as the Neuroscience, Applied Mathematics, and Biomedical Engineering graduate interdisciplinary programs (GIDPs). Dr. Witte's vision is to develop a new generation of young investigators steeped in multiple disciplines branching from neuroscience, neural engineering, biochemistry, mathematics, biomedical imaging and, physics. He welcomes dreamers, brainstormers and problems solvers to join his team in search of the next great discovery in physics and medicine. Keywords: Biomedical Engineering/Medical Imaging

Karen Schumaker, PhD, understands that activities of living organisms require the performance of chemical, mechanical, osmotic or electrical work. The energy required for this work is supplied by metabolism, respiration, photosynthesis and fermentation. Adenosine triphosphate (ATP) has long been recognized as the universal energy currency, with metabolism supporting the synthesis of ATP and the hydrolysis of ATP being used for the subsequent work. However, ATP is not the only energy currency in living organisms. A second and very different energy currency links metabolism to work by a current of ions passing from one side of a membrane to the other. These ion currents play a major role in energy capture and they support a range of physiological processes from the active transport of nutrients to the removal of toxic ions. To more efficiently capture and utilize energy, it will be necessary to uncover mechanisms regulating these ion currents. In a project funded by the Physical Biosciences Program of the Office of Basic Energy Sciences at the Department of Energy, Dr. Schumaker asks how calcium-binding proteins regulate the activity of specific secondary active transporters to control cellular sodium ion homeostasis during plant growth in saline conditions.The build-up of salt in agricultural soils is a widespread problem that limits the growth and yield of important crop species worldwide. While genetic variation for plant growth in salinity (salt tolerance) exists, little is known about the genes and pathways underlying this variation. In a project funded by the Physiological and Structural Systems Cluster in the Division of Integrative Organismal Systems at the National Science Foundation, Dr. Schumaker’s lab analyzes the molecular evolution of the genes and associated networks that control plant adaptation to soil salinity. To do this, they are assessing the evolutionary forces acting on plant salt tolerance and mapping and isolating genes that underlie natural variation for this trait.