Plenary Talks

09:50 - 10:35 : Friedman, Avner (P) (Mathematical Biosciences Institute, Ohio State University)
-Title: What is mathematical biology and how useful is it?
I shall define what is meant by 'mathematical biology', and then proceed to illustrate the degree of its usefulness by examples taken from projects developed at the Mathematical Biosciences Institute: chronic wound healing; modeling of the immune rheostat of macrophages in the lung in response to infection; neointimal hyperplasia occurring in dialysis, tuberculosis as a disease with prognosis which depends on the age of the patient, and viral treatment of glioblastoma. All these examples are modeled by systems of differential equations, and the challenges are: 1) Researching the biological literature in order to set up a mathematical model; 2) Determining the rate parameters; 3) Simulating the model. The final test is to show good fit with experimental results, after which the model can be used to suggest new biologically testable hypotheses.

10:35 - 11:20 : Alber, Mark S. (P) (Center for the Study of Biocomplexity, University of Notre Dame)
-Title: Multiscale Modeling in Biology
A multiscale model of blood clot formation will be described which combines a detailed tissue factor pathway submodel of blood coagulation, a blood flow submodel and a stochastic discrete cell submodel [1,2]. It will be shown that low levels of FVII in blood result in a significant delay in thrombin production demonstrating that FVII plays an active role in promoting clot development at an early stage. We will also describe a new subcellular element method for simulating cellular blood components. In addition, multiscale models of chemotactic cell motion [3] and bacterial swarming will be discussed [4].
[1]. Xu, Z., J. Lioi, J. Mu, X. Liu, M.M. Kamocka, E.D. Rosen, D.Z. Chen and M.S. Alber, A Multiscale Model of Venous Thrombus Formation with Surface-Mediated Control of Blood Coagulation Cascade, Biophysical Journal (to appear).
[2]. Xu, Z., Chen, N., , Kamocka, M.M., Rosen, E.D., and M.S. Alber [2008], Multiscale Model of Thrombus Development, Journal of the Royal Society Interface, 5 705-722.
[3]. Lushnikov, P.P., Chen, N., and M.S. Alber [2008], Macroscopic dynamics of biological cells interacting via chemotaxis and direct contact, Phys. Rev. E. 78, 061904
[4]. Wu, Y., Jiang, Y., Kaiser, D., and M. Alber [2009], Periodic reversal of direction allows Myxobacteria to swarm, Proc. Natl. Acad. Sci. USA, 106 4 1222-1227 (featured in the Nature News, January 20th, 2009, doi:10.1038/news.2009.43).

5:15 - 6:00 : Sander, Leonard M. (P) (Physics, University of Michigan-Ann Arbor)
-Title: Biomechanics of cell motility in Dictyostelium
The mechanics of cell motility has a number of surprising features that need to be included in models of the process. Recent experiments on the motion of the ameba Dictyostelium discoideum in chemotaxis show that contractile forces on the substrate are two orders of magnitude larger than the force necessary to propel the cell forward against fluid friction. Most of the work done by the cell goes towards peeling it from the substrate (breaking the adhesive bonds); viscoelastic effects and friction are completely negligible. We give a new mechanical model based on this idea, and show how it agrees with experimental results on the cell speed of wild-type and mutated dicty.