Atherosclerotic lesions are found opposite vascular flow dividers at sites of low shear stress and oscillatory flow. Since endothelial proinflammatory genes prominent in lesions are regulated by oxidation-sensitive transcriptional control mechanisms, we examined the redox state of cultured human umbilical vein endothelial cells after either oscillatory or steady laminar fluid shear stress. Endo...

The vascular endothelium is exposed to a spectrum of fluid mechanical forces generated by blood flow; some of these, such as fluid shear stress, can directly modulate endothelial gene expression. Previous work by others and in our laboratory, using an in vitro uniform laminar shear stress model, has identified various shear stress response elements (SSREs) within the promoters of certain endoth...

The ability to discriminate cell adhesion molecule expression between healthy and inflamed endothelium is critical for therapeutic intervention in many diseases. This study explores the effect of laminar flow on TNFα-induced E-selectin surface expression levels in human umbilical vein endothelial cells (HUVECs) relative to IL-1β-induced expression via flow chamber assays. HUVECs grown in static...

Regions of the arterial tree exposed to laminar flow, which exerts high shear stress, are protected from inflammation, endothelial cell (EC) death and atherosclerosis. TNFalpha activates NF-kappaB transcription factors, which potentially exert dual functions by inducing both proinflammatory and cytoprotective transcripts. We assessed whether laminar shear stress protects EC by modulating NF-kap...

Fluid shear stress is an important regulator of vascular and endothelial cell (EC) functions. Its effect is dependent not only on magnitude but also on flow type. Although laminar flow predominates in the vasculature, transitional flow can occur and is thought to play a role in vascular diseases. While a great deal is known about the mechanisms and signaling cascades through which laminar shear...

The ventricular myocardium consists of a syncytium of myocytes organized into branching, transmurally oriented laminar sheets approximately four cells thick. When systolic deformation is expressed in an axis system determined by the anatomy of the laminar architecture, laminar sheets of myocytes shear and laterally extend in an approximately radial direction. These deformations account for ~90%...

T he vascular endothelium, the major interface of the vessel wall between blood and all tissues, must constantly adapt to fluctuations in environmental cues. Cellular metabolism is one mechanism that may contribute to rapid dynamic changes in cell phenotype. For example, glycolysis, one of the major forms of cellular metabolism that converts glucose to pyruvate, is required for immune cell acti...

In the present work, the effect of Soil-Structure Interaction (SSI) in low frequency structures resting on loose soil, through numerical modelling and shaking table tests have been studied. In theoretical studies two types of models namely fixed base and flexible base structure were subjected to three selected earthquake records. Nonlinear dynamic analysis was employed for all of the numerical ...

We present an analytical model for jets in Fanaroff & Riley Class I (FR I) radio galaxies, in which an initially laminar, relativistic flow is surrounded by a shear layer. We apply the appropriate conservation laws to constrain the jet parameters, starting the model where the radio emission is observed to brighten abruptly. We assume that the laminar flow fills the jet there and that pressure b...

Alterations in the functions of vascular endothelial cells (ECs) induced by fluid shear stress may play a pivotal role in both the development and prevention of vascular diseases. We found that DNA synthesis of bovine aortic and human umbilical vein ECs, determined by [H]thymidine incorporation, was inhibited by steady laminar shear stress (5 and 30 dyne/cm). This growth inhibition due to shear...