Graduation date: 1997

Thesis (Ph. D.)--University of Hong Kong, 2006.

Marfan syndrome, affecting approximately one out of every 5,000 people, is characterized by abnormal bone growth, ectopia lentis, and often-fatal aortic dilation and dissection. The root cause is a faulty extracellular matrix protein, fibrillin-1, which associates with elastin in many tissues. Common carotids from wild-type controls and mice heterozygous for the mgR mutation, the most commonly used mouse model of Marfan syndrome, were studied in a biaxial testing device. Mechanical data in the form of pressure-diameter and force-stretch tests in both the active and passive states were collected, as well data on the functional responses to phenylephrine, carbamylcholine chloride, and sodium nitroprusside. Although little significant difference was found between the heterozygous and wild-type groups in general, the in vivo stretch for both groups was significantly different from previously studied mouse vessels. Although the two groups do not exhibit significant differences, this study comprises a control group for future work with mice homozygous for mgR, which do exhibit Marfan-like symptoms. As treatment of Marfan syndrome improves, more Marfan patients will survive and age, increasing the likelihood that they will develop many of the vascular complications affecting the normal population, including hypertension and atherosclerosis. Therefore, it is imperative to gather biomechanical data from the Marfan vasculature so that clinicians may predict the effects of vascular complications in Marfan patients and develop appropriate methods of treatment.

Nature encourages diversity in life forms (morphologies). The study of morphogenesis deals with understanding those processes that arise during the embryonic development of an organism. These processes control the organized spatial distribution of cells, which in turn gives rise to the characteristic form for the organism. Morphogenesis is a multi-scale modeling problem that can be studied at the molecular, cellular, and tissue levels. Here, we study the problem of morphogenesis at the cellular level by introducing an integrated biomechanical model of cells embedded in the extracellular matrix. The fundamental aspects of mechanobiology essential for studying morphogenesis at the cellular level are the cytoskeleton, extracellular matrix (ECM), and cell adhesion. Cells are modeled using tensegrity architecture. Our simulations demonstrate cellular events, such as differentiation, migration, and division using an extended tensegrity architecture that supports dynamic polymerization of the micro-filaments of the cell. Thus, our simulations add further support to the cellular tensegrity model. Viscoelastic behavior of extracellular matrix is modeled by extending one-dimensional mechanical models (by Maxwell and by Voigt) to three dimensions using finite element methods. The cell adhesion is modeled as a general Velcro-type model. We integrated the mechanics and dynamics of cell, ECM, and cell adhesion with a geometric model to create an integrated biomechanical model. In addition, the thesis discusses various computational issues, including generating the finite element mesh, mesh refinement, re-meshing, and solution mapping. As is known from a molecular level perspective, the genetic regulatory network of the organism controls this spatial distribution of cells along with some environmental factors modulating the process. The integrated biomechanical model presented here, besides generating interesting morphologies, can serve as a mesoscopic-scale platform upon which future work can correlate with the underlying genetic network.

Thesis (Ph. D.)--University of Chicago, Dept. of Chemistry, June 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.)--Virginia Commonwealth University, 2009. / Prepared for: Dept. of Biomedical Engineering. Title from resource description page. Includes bibliographical references.

Thesis (M.Sc.)--York University, 2007. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 119-133). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38842

Thesis (Ph. D.)--University of Missouri--Columbia, 2003. / Typescript. Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri--Columbia, 2003. / "May 2003." Typescript. Vita. Includes bibliographical references.

The objective of the presented research is to examine the relationship between the cellular microenvironment and biochemical response of metastatic cells. Clinically recognized as a trait of cancer progression, the cellular microenvironment can have variable and distinct mechanical properties that are processed via cellular mechanosensing, resulting in a cellular biochemical response. A range of studies investigating the interactions between the cellular micromechanical environment and the cell's molecular response during disease progression have been made, yet remain absent of quantitative characterization of many of these coordinated responses. The fundamental inquiry that drives the following research attempts to elucidate how a cell perceives the physical microenvironment and converts that signal to a biochemical response. With the goal of providing insight to such responses, the presented research seeks to elucidate the following questions: (1) What are the integrated effects of ECM stiffness, ECM architecture, and breast cancer cell metastatic potential on cell migration? (2) How does endogenous tissue transglutaminase (tTG) cross-linking of the ECM scaffold effect ECM mechanical properties? (3) How does the architecture and stiffness of the extracellular matrix (ECM) effect the systems-level cellular migration and signaling response? (4) What are the integrated effects of ECM architecture and the targeted knockdown of integrin [beta]1 and MT1-MMP on cellular metastatic potential? The presented research utilizes an interdisciplinary approach, integrating experimental mechanics, biochemical analysis, cellular biology techniques, covalent chemistry, and various microscopy techniques, to investigate these events. In short, cancerous cells are cultured atop or within synthetic collagen type I ECMs of varying mechanical stiffness and structure. These cells are subsequently analyzed by molecular analysis and immunoassays, including quantitative PCR, Western blotting, and gelatin zymography, to acquire measures of the cellular response to perturbations of micromechanical environment. Time-lapse microscopy experiments and subsequent image analyses enable observations of cellular migratory potential through synthetic ECMs. Results indicate that cooperative synergy between ECM properties, cell-matrix adhesion, and pericellular proteolysis drive cell migratory potential of highly invasive tumorigenic cell populations. Collectively, these findings contribute to the cancer biology and mechanobiology fields by systematically extending current insights of matrix mechanics, cellular signaling, and cellular migratory potential in cancer. / text