Sat, 26 Jul 2008 03:22:17 BST CiteULike: matthewhflamm adhesion http://www.citeulike.org/user/matthewhflamm/tag/adhesion CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/matthewhflamm/article/2602843 <i></i><br /><br />A theoretical framework is proposed for the analysis of adhesion between cells or of cells to surfaces when the adhesion is mediated by reversible bonds between specific molecules such as antigen and antibody, lectin and carbohydrate, or enzyme and substrate. From a knowledge of the reaction rates for reactants in solution and of their diffusion constants both in solution and on membranes, it is possible to estimate reaction rates for membrane-bound reactants. Two models are developed for predicting the rate of bond formation between cells and are compared with experiments. The force required to separate two cells is shown to be greater than the expected electrical forces between cells, and of the same order of magnitude as the forces required to pull gangliosides and perhaps some integral membrane proteins out of the cell membrane. Models for the Specific Adhesion of Cells to Cells George Bell 2008-03-27T17:56:32-00:00 adhesion detachment receptor http://www.citeulike.org/user/matthewhflamm/article/2599533 <i>Langmuir, Vol. 12, No. 9. (1 May 1996), pp. 2271-2282.</i><br /><br />Abstract: In biological adhesion experiments, cells use surface receptors to attach to ligand-coated substrata, and forces, such as centrifugation or shear forces, are used to remove cells. Receptors bind with a high-affinity lock-and-key mechanism, and their bonds are weaker than covalent bonds. The magnitude of the force at which the cell relents is quoted as the strength of adhesion. However, the character or direction of the force, which depends on the adhesion assay, can affect the results of an adhesion assay, even if forces of precisely the same magnitude are applied in the different assays. We demonstrate this principle by simulating the detachment of receptor-coated hard spheres from ligand-coated surfaces using normal, tangential, and shear forces after the particles are allowed to bind to steady state. For a single bond, a 20-fold greater force is required to detach the particle if a normal, rather than tangential, force is applied. At high receptor densities, tangential forces can be as much as 56 times more disruptive than normal forces in removing cells from surfaces. The higher sensitivity to tangential forces is because body forces exerted tangentially are focused on bonds at the back edge of contact and because the ratio of bond length to bead radius is small, which constrains the bonds in an orientation near to normal to the substrate and results in large axial bond tensions. Hydrodynamic shear, and with its associated torque, is only slightly more disruptive than a tangential force of the same magnitude. Forces applied at an angle to the substrate from 0 (tangent) to 80 are as effective as a tangential force at detaching a particle. Our simulations provide a rational means for comparing the results between different adhesion assays. Influence of Direction and Type of Applied Force on the Detachment of Macromolecularly-Bound Particles from Surfaces KC Chang DA Hammer doi:10.1021/la950690y Langmuir, Vol. 12, No. 9. (1 May 1996), pp. 2271-2282. 2008-03-26T19:04:47-00:00 1996 Langmuir 12 9 2271 2282 adhesion http://www.citeulike.org/user/matthewhflamm/article/2599451 <i>Proceedings of the National Academy of Sciences, Vol. 97, No. 21. (10 October 2000), pp. 11262-11267.</i><br /><br />10.1073/pnas.200240897 The state diagram for cell adhesion under flow: Leukocyte rolling and firm adhesion Kai-Chien Chang David Tees Daniel Hammer doi:10.1073/pnas.200240897 Proceedings of the National Academy of Sciences, Vol. 97, No. 21. (10 October 2000), pp. 11262-11267. 2008-03-26T18:31:31-00:00 2000 Proceedings of the National Academy of Sciences 97 21 11262 11267 adhesion flow leukocyte