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J. P. Mills^1,1, L. Qie^2,2, M. Dao^1,1, C. T. Lim^2,2, S. Suresh^1,3
Molecular & Cellular Biomechanics, Vol.1, No.3, pp. 169-180, 2004, DOI:10.3970/mcb.2004.001.169
Abstract Studies of the deformation characteristics of single biological cells can offer insights into the connections among mechanical state, biochemical response and the onset and progression of diseases. Deformation imposed by optical tweezers provides a useful means for the study of single cell mechanics under a variety of well-controlled stress-states. In this paper, we first critically review recent advances in the study of single cell mechanics employing the optical tweezers method, and assess its significance and limitations in comparison to other experimental tools. We then present new experimental and computational results on shape evolution, force--extension curves, elastic properties and viscoelastic response… More >

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Tanmay Lele^1,1, Philmo Oh^1,1, Jeffrey A. Nickerson^1,1,2,2, Donald E. Ingber^1,1,3,3
Molecular & Cellular Biomechanics, Vol.1, No.3, pp. 181-190, 2004, DOI:10.3970/mcb.2004.001.181
Abstract The estimation of binding constants and diffusion coefficients of molecules that associate with insoluble molecular scaffolds inside living cells and nuclei has been facilitated by the use of Fluorescence Recovery after Photobleaching (FRAP) in conjunction with mathematical modeling. A critical feature unique to FRAP experiments that has been overlooked by past mathematical treatments is the existence of an `equilibrium constraint': local dynamic equilibrium is not disturbed because photobleaching does not functionally destroy molecules, and hence binding-unbinding proceeds at equilibrium rates. Here we describe an improved mathematical formulation under the equilibrium constraint which provides a more accurate estimate of molecular reaction… More >

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H. Gregersen¹, G.S. Kassab², Y.C. Fung²
Molecular & Cellular Biomechanics, Vol.1, No.3, pp. 191-200, 2004, DOI:10.3970/mcb.2004.001.191
Abstract During the last decades, it has become increasingly common to make balloons distension in visceral organs in vivo. In particular this is true for studies of gastrointestinal motor function and biomechanics. Balloon distension is often used for assessment of small intestinal compliance and tension based on Laplace's law for cylindrical pressure pipes. This commonly used law is valid only when the balloon-distended intestine is cylindrical. Experimentally, it is seen that the diameter of the balloon-distended intestine is not a constant, but variable in the axial direction. Hence, it is necessary to improve Laplace's law for intestinal investigation. In this paper… More >

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701

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Roger D. Kamm^1,1,2,2, Mohammad R. Kaazempur-Mofrad^1,1
Molecular & Cellular Biomechanics, Vol.1, No.3, pp. 201-210, 2004, DOI:10.3970/mcb.2004.001.201
Abstract Much is currently known about the signaling pathways that are excited when cells are subjected to a mechanical stimulus, yet we understand little of the process by which the mechanical perturbation is transformed into a biochemical signal. Numerous theories have been proposed, and each has merit. While cells may possess many different ways of responding to stress, the existence of a single unifying principle has much appeal. Here we propose the hypothesis that cells sense mechanical force through changes in protein conformation, leading to altered binding affinities of proteins, ultimately initiating an intracellular signaling cascade or producing changes in the… More >

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677

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Min Yue^1,1, Jeanne C. Stachowiak^1,1,2,2, Arunava Majumdar^1,1,3,3
Molecular & Cellular Biomechanics, Vol.1, No.3, pp. 211-220, 2004, DOI:10.3970/mcb.2004.001.211
Abstract Microchips;ontaining arrays of cantilever beams have been used to mechanically detect and quantitatively analyze multiple reactions of DNA hybridization and antigen-antibody binding simultaneously. The reaction-induced deflection of a cantilever beam reflects the interplay between strain energy increase of the beam and the free energy reduction of a reaction, providing an ideal tool for investigating the connection between mechanics and chemistry of biomolecular reactions. Since free energy reduction is common for all reactions, the cantilever array forms a universal platform for label-free detection of various specific biomolecular reactions. A few such reactions and their implications in biology and biotechnology are discussed. More >

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710

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Alvaro Valencia¹
Molecular & Cellular Biomechanics, Vol.1, No.3, pp. 221-232, 2004, DOI:10.3970/mcb.2004.001.221
Abstract Flow dynamics play an important role in the pathogenesis and treatment of intracranial aneurysms. The evaluation of the velocity field in the aneurysm dome and neck is important for the correct placement of endovascular coils, and the temporal and spatial variations of wall shear stress in the aneurysm are correlated with its growth and rupture. This numerical investigation describes the hemodynamic in two models of terminal aneurysm of the basilar artery. Aneurysm models with a aspect ratio of 1.0 and 1.67 were studied. Each model was subject to physiological representative waveform of inflow for a mean Reynolds number of 560.… More >

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