Degree Type

Dissertation

Date of Award

1994

Degree Name

Doctor of Philosophy

Department

Chemical and Biological Engineering

First Advisor

Alison B. Flatau

Abstract

Fifty percent of all the deaths in the Western world can be attributed to diseases of the cardiovascular system. A major player amongst these diseases is atherosclerosis. Atherosclerosis is the localized thickening of the arterial wall and is primarily due to the proliferation of fibrous tissue and smooth muscle cells in conjunction with the deposition of lipids within the wall. The hypothesis investigated was that high frequency, low amplitude vibratory environments similar to those found in regions of disturbed flow, which are coincident with intimal thickenings, the earliest stage of atherosclerosis, do elicit a proliferative response in vascular smooth muscle cells without the introduction of outside agents such as biochemicals derived from endothelial cells or blood borne particles. Research done in this study that provides evidence to lend credence to this hypothesis involved culturing vascular smooth muscle cells in high frequency, small amplitude vibratory environments;An analytical model of the wall of an artery was developed that treated the vessel as a distensible, axisymmetric, curvilinearly-isotropic, straight, semi-infinite, thin-walled cylinder in bending with a circular cross-sectional area. The equations of motion developed for these regions demonstrate that there is a relationship between wall properties and how the wall moves in response to an outside force;A test stand which was capable of subjecting vascular smooth muscle cells to either vibration levels assumed to mimic those found in the regions of disturbed flow, ranging from 45 Hz and 12 [mu]m to 15 Hz and 4 [mu]m, or of isolating them from essentially all vibration was designed and assembled;The in vitro examination done in this study looked at the effects of vibration on vascular smooth muscle cells. Reliable and efficient procedures were developed and followed to isolate, culture, identify, and quantify vascular smooth muscle cells for use in this study. A new method of quantifying cells, alamarBlue[superscript] TM, which had never before been used on vascular smooth muscle cells was evaluated and procedures for its use were developed;Analysis of the data, from 5 different levels of vibration, on the growth rates of vascular smooth muscle cells led to several conclusions. (1) High frequency vibration at various small amplitudes of motion (4 [mu]m and 12 [mu]m at 15 HZ, 8 [mu]m at 30 Hz, and 4 [mu]m at 45 Hz) had no effect on growth rates. (2) Cells that were subjected to vibration levels of 12 [mu]m 45 Hz grew at a significantly higher rate than did cells grown in static conditions. (3) There is a relationship between the dynamic environment of vascular smooth muscle cells and the rates at which they proliferate.

DOI

https://doi.org/10.31274/rtd-180813-12262

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Becky Bellatti Bittle

Language

en

Proquest ID

AAI9518359

File Format

application/pdf

File Size

289 pages

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