Vol.4, No.1, 2007-Table of Contents
  • Orientation of Apical and Basal Actin Stress Fibers in Isolated and Subconfluent Endothelial Cells as an Early Response to Cyclic Stretching
  • Abstract We investigated the response of apical and basal actin stress fibers (SFs) and its dependency on cell confluency for endothelial cells subjected to cyclic stretching. Porcine aortic endothelial cells from the 2nd and 5th passages were transferred to a fibronectin-coated silicone chamber with 5000–8000 cells/cm2(isolated condition), positioning the cells apart, or with 25,000–27,000 cells/cm2(subconfluent condition), allowing cell-to-cell contact. The substrate was stretched cyclically by 0.5 Hz for 2 h with a peak strain on the substrate that was 15% in the stretch direction and –4% in the transverse direction. The actin filaments (AFs) were stained with rhodamine phalloidin and their… More
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  • Mechanical Loading by Fluid Shear Stress Enhances IGF-1 Receptor Signaling in Osteoblasts in A PKC ζ -Dependent Manner
  • Abstract Maintenance of optimal bone physiology requires the coordinated activity of osteoclasts that resorb old bone and osteoblasts that deposit new bone. Mechanical loading of bone and the resulting movement of interstitial fluid within the spaces surrounding bone cells is thought to play a key role is maintaining optimal bone mass. One way in which fluid movement may promote bone formation is by enhancing osteoblast survival. We have shown previously that application of fluid flow to osteoblasts in vitro confers a protective effect by inhibiting osteoblast apoptosis (Pavalko et al., 2003, J. Cell Physiol., 194: 194-205). To investigate the cellular mechanisms… More
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  • Theoretical Analysis of Thermal Damage in Biological Tissues Caused by Laser Irradiation
  • Abstract A bioheat transfer approach is proposed to study thermal damage in biological tissues caused by laser radiation. The laser light propagation in the tissue is first solved by using a robust seven-flux model in cylindrical coordinate system. The resulting spatial distribution of the absorbed laser energy is incorporated into the bioheat transfer equation for solving temperature response. Thermal damage to the tissue is assessed by the extent of denatured protein using a rate process equation. It is found that for the tissue studied, a significant protein denaturation process would take place when temperature exceeds about 53oC. The effects of laser… More
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  • Numerical Simulations of Pulsatile Flow in an End-to-Side Anastomosis Model
  • Abstract A potential interaction between the local hemodynamics and the artery wall response has been suggested for vascular graft failure by intimal hyperplasia (IH). Among the various hemodynamic factors, wall shear stress has been implicated as the primary factor responsible for the development of IH. In order to explore the role of hemodynamics in the formation of IH in end-to-side anastomosis, computational fluid dynamics is employed. To validate the numerical simulations, comparisons with existing experimental data are performed for both steady and pulsatile flows. Generally, good agreement is observed with the velocity profiles whereas some discrepancies are found in wall shear… More
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  • Inflation of An Artery Leading to Aneurysm Formation and Rupture
  • Abstract Formation and rupture of aneurysms due to the inflation of an artery with collagen fibers distributed in two preferred directions, subjected to internal pressure and axial stretch are examined within the framework of nonlinear elasticity. A two layer tube model with a fiber-reinforced composite based incompressible anisotropic hyperelastic constitutive material is employed to model the stress-strain behavior of the artery wall with distributed collagen fibers. The artery wall takes up a uniform inflation deformation, and there are no aneurysms in the artery under the normal condition. But an aneurysm may be formed in arteries when the stiffness of the fibers… More
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