The vascular vessel wall is constantly exposed to biomechanical forces, such as shear and tensile stress. Biomechanical forces are important for several physiological and pathological processes and have been shown to regulate a number of fundamental vascular functions, such as vascular tone and remodeling processes. The aim of the present thesis was to study the effects of biomechanical forces ...

IMPACT RESISTANT GLASSY POLYMERS: PRE-STRESS AND MODE II FRACTURE FEBRUARY 2013 JARED STEVEN ARCHER B.S., WESTERN WASHINGTON UNIVERSITY M.S., UNIVERSITY OF MASSACHUSETTS AMHERST Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Alan J. Lesser Model glassy polymers, polymethyl methacrylate (PMMA) and polycarbonate (PC) are used to experimentally probe several aspects of polymer f...

A flow apparatus has been developed for the study of the metabolic response of anchorage-dependent cells to a wide range of steady and pulsatile shear stresses under well-controlled conditions. Human umbilical vein endothelial cell monolayers were subjected to steady shear stresses of up to 24 dynes/cm(2), and the production of prostacyclin was determined. The onset of flow led to a burst in pr...

OBJECTIVES It has been postulated that in the arterial system mean wall shear stress is maintained at a constant value. The present study was performed to investigate the level of wall shear stress in the common carotid artery (CCA) as function of age and possible interactions between diameter and storage capacity, defined as the absolute area change per heart beat, with mean wall shear stress....

OBJECTIVE Fluid shear stress induces cyclooxygenase (COX)-2 gene expression in vascular endothelial cells. We investigated the underlying mechanism of this induction. METHODS AND RESULTS Exposure of human umbilical vein endothelial cells to laminar shear stress in the physiological range (1 to 30 dyne/cm2) upregulated the expression of COX-2 but not COX-1, a constitutive isozyme of COX. The e...

OBJECTIVE Bone morphogenetic protein 4 (BMP-4) is a transforming growth factor beta family member cytokine that exerts proinflammatory effects on the endothelium and is likely to play a role in atherogenesis. Recent studies suggested that atheroprotective levels of shear stress control endothelial BMP-4 expression; however, the underlying mechanisms remained unknown. METHODS AND RESULTS We fo...

Fluid shear stress modulates vascular production of endothelial superoxide anion (O2*-) and nitric oxide (*NO). Whether the characteristics of shear stress influence the spatial variations in mitochondrial manganese superoxide dismutase (Mn-SOD) expression in vasculatures is not well defined. We constructed a three-dimensional computational fluid dynamics model simulating spatial variations in ...

The two-dimensional low-speed structure of a turbulent boundary layer has been clearly visualized by a combination of a shear stress sensor using micro electro mechanical systems and the discrete wavelet transform. The application of two-dimensional discrete wavelet transforms to the visualization of wall shear stress data obtained using the micro shear stress imaging chip is described. The exp...

Aging impairs shear-stress-dependent dilation of arteries via increased superoxide production, decreased SOD activity, and decreased activation of endothelial nitric oxide (NO) synthase (eNOS). In the present study, we investigated whether chronic increases in shear stress, elicited by increases in blood flow, would improve vascular endothelial function of aged rats. To this end, second-order m...