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Research Focus Bioengineering, Transport Phenomena, Membrane Separations The common theme of our research group is the application of engineering principles to biological materials or systems. Most of the problems we work on are motivated by a desire to understand normal or pathophysiological processes occurring in the body, and their implications for the prevention, diagnosis, or treatment of human disease. Much of the work entails collaboration with physicians, physiologists, and other biological scientists. One area of focus involves the fundamentals of water and macromolecule transport in liquid-filled spaces of molecular dimensions. This is important for understanding mass transfer in body tissues, as well as for designing membranes or other separation devices. A key objective of our work is to develop models to predict transport hindrances in porous or fibrous materials, based on the size, shape, and electrical charge of the permeating molecule and the nanostructural properties of the material. The theoretical models are tested using membranes or gels of well-defined structure. They are used also to interpret experiments that probe the permeability properties of mammalian kidney capillaries in health and disease. We are endeavoring to relate the ultrastructure of those capillaries to their transport characteristics, through detailed analyses of convection and diffusion at the cellular and subcellular levels. Another area of interest is transport and reaction of nitric oxide (NO) in biological systems. It has been shown in recent years that NO is synthesized throughout the body and that it is a key intercellular messenger molecule (e.g., in the regulation of blood pressure). Transient increases in NO synthesis are important also in the response of the immune system to infection, in that the toxicity of NO helps to kill invading microorganisms. However, sustained high levels of NO synthesis (as may occur with chronic infection or inflammation) carries with it the risk of collateral damage to host tissues, including mutational changes that may lead to cancer. To provide insight into the biological effects of NO and of the various reactive NOx species derived from NO, we are studying reaction kinetics and diffusion in aqueous solutions and cell cultures. Using such data, we are developing computational models to predict the consequences of NO synthesis by cells in vivo or in vitro. Representative Publications & Lectures "Analysis of the effects of cell spacing and liquid depth on nitric oxide and its oxidation products in cell cultures," Chem. Res. Toxicol., 14, 135-147 (2001), (with B. Chen). "Concentration polarization in stirred ultrafiltration cells," AIChE J., 47, 1115-1125 (2001), (with S.T. Johnston and K.A. Smith). "Equilibrium partitioning of flexible macromolecules in fibrous membranes and gels," Macromolecules, 33, 8504-8511 (2000), (with J.A. White). "Effects of multisolute steric interactions on membrane partition coefficients," J. Colloid Interface Sci., 226, 112-122 (2000), (with M.J. Lazzara and D. Blankschtein). "Ultrastructural model for size selectivity in glomerular filtration," Am. J. Physiol., 276, F892-F902 (1999), (with A. Edwards and B.S. Daniels). "Diffusion and reaction of nitric oxide in suspension cell
cultures," Biophys. J., 75, 745-754 (1998), (with B. Chen
and M. Keshive). |
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