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Full-Text Articles in Biomedical Engineering and Bioengineering

A 3d Simulation Of Leukocyte Adhesion In Blood Flow, Tai-Hsien Wu Jun 2018

A 3d Simulation Of Leukocyte Adhesion In Blood Flow, Tai-Hsien Wu

Dissertations

It has been widely acknowledged that further understanding about the dynamics between blood cells and blood flow can help us gain more knowledge about the causes of diseases and discover more effective treatments. Examples of such dynamics include red blood cell (RBC, or erythrocyte) aggregation, white blood cell (WBC, or leukocyte) margination, and WBC extravasation. WBC extravasation is an important multiple-step process in the inflammatory response and therefore has drawn considerable attention over the past two decades. In this multiple-step process, a WBC undergoes at least four steps, including capture, rolling, firm adhesion, and transmigration, and each step is influenced ...


Fabricating Cost-Effective Nanostructures For Biomedical Applications, Erden Ertorer Sep 2013

Fabricating Cost-Effective Nanostructures For Biomedical Applications, Erden Ertorer

Electronic Thesis and Dissertation Repository

In this thesis we described inexpensive alternatives to fabricate nanostructures on planar substrates and provided example applications to discuss the efficiency of fabricated nanostructures.

The first method we described is forming large area systematically changing multi-shape nanoscale structures on a chip by laser interference lithography. We analyzed the fabricated structures at different substrate positions with respect to exposure time, exposure angle and associated light intensity profile. We presented experimental details related to the fabrication of symmetric and biaxial periodic nanostructures on photoresist, silicon surfaces, and ion-milled glass substrates. Behavior of osteoblasts and osteoclasts on the nanostructures was investigated. These results ...


Biomaterial-Microvasculature Interactions, Alisha Sarang-Sieminski, Keith Gooch Apr 2012

Biomaterial-Microvasculature Interactions, Alisha Sarang-Sieminski, Keith Gooch

Alisha L. Sarang-Sieminski

The utility of implanted sensors, drug-delivery systems, immunoisolation devices, engineered cells, and engineered tissues can be limited by inadequate transport to and from the circulation. As the primary function of the microvasculature is to facilitate transport between the circulation and the surrounding tissue, interactionsbetween biomaterials and the microvasculature have been explored to understand the mechanisms controlling transport to implanted objects and ultimately improve it. This review surveys work on biomaterial-microvasculature interactions with a focus on the use of biomaterials to regulate the structure and function of the microvasculature. Several applications in which biomaterial-microvasculature interactions play a crucial role are briefly ...


Epidermal Growth Factor-Induced Contraction Regulates Paxillin Phosphorylation To Temporally Separate Traction Generation From De-Adhesion, Ian C. Schneider, Cristen K. Hays, Clare M. Waterman Jul 2009

Epidermal Growth Factor-Induced Contraction Regulates Paxillin Phosphorylation To Temporally Separate Traction Generation From De-Adhesion, Ian C. Schneider, Cristen K. Hays, Clare M. Waterman

Chemical and Biological Engineering Publications

Directed cell migration is mediated by cycles of protrusion, adhesion, traction generation on the extracellular matrix and retraction. However, how the events after protrusion are timed, and what dictates their temporal order is completely unknown. We used acute epidermal growth factor (EGF) stimulation of epidermal keratinocytes to initiate the cell migration cycle to study the mechanism of the timing of adhesion, traction generation, and de-adhesion. Using microscopic and biochemical assays, we surprisingly found that at ∼2 min after EGF stimulation protrusion, activation of myosin-II, traction generation, adhesion assembly, and paxillin phosphorylation occurred nearly simultaneously, followed by a 10-min delay during ...


Gene Synthesis, Cloning, Expression, Purification And Biophysical Characterization Of The C2 Domain Of Human Tensin, Kiran Sukumar Gajula Oct 2007

Gene Synthesis, Cloning, Expression, Purification And Biophysical Characterization Of The C2 Domain Of Human Tensin, Kiran Sukumar Gajula

Doctoral Dissertations

Tensin is a large "docking" protein found in the adhesive junctions of animal cells and recruited early in the development of cell-substrate contacts. There it binds to the cytoplasmic domain of integrin β1 and caps the barbed ends of filamentous actin. This forms a rational basis for its implication in a direct role in the mechanics of membrane-cytoskeleton interactions. Tensin provides a physical link between the actin cytoskeleton, integrins, and other proteins at the cell-substrate contacts. Its overall biochemical properties are a function of its domain composition and architecture, i.e., the domains that are present and their relative positions ...


Determination Of The Mechanical Properties Of Electrospun Gelatin Based On Polymer Concentration And Fiber Alignment, Leander Taylor Iii Jan 2006

Determination Of The Mechanical Properties Of Electrospun Gelatin Based On Polymer Concentration And Fiber Alignment, Leander Taylor Iii

Theses and Dissertations

The process of electrospinning has given the field of tissue engineering insight into many aspects of tissue engineered scaffolds, including how factors such as fiber diameter and porosity are affected by polymer concentration. However, the affects of fiber alignment upon the material properties of electrospun scaffolds remains unclear. The purpose of this study is to determine how the material properties of electrospun gelatin scaffolds are affected by changes in fiber alignment and starting gelatin concentration. Gelatin scaffolds, with starting concentrations of 80, 100, and 130mg/m1, were electrospun onto a target mandrel rotating at various speeds. Samples of each scaffold ...


Synergistic Effects Of Physical And Chemical Guidance Cues On Neurite Alignment And Outgrowth On Biodegradable Polymer Substrates, Cheryl Miller, Srdija Jeftinija, Surya K. Mallapragada Jan 2002

Synergistic Effects Of Physical And Chemical Guidance Cues On Neurite Alignment And Outgrowth On Biodegradable Polymer Substrates, Cheryl Miller, Srdija Jeftinija, Surya K. Mallapragada

Chemical and Biological Engineering Publications

This article demonstrates that directional outgrowth of neurites is promoted by applying a combination of physical and chemical cues to biodegradable polymer substrates. Films of poly-D,L-lactic acid and poly(lactide-co-glycolide) were micropatterned to form grooves on substrate surfaces, using novel indirect transfer techniques developed specifically for biodegradable polymers that cannot be micropatterned directly. Laminin was selectively adsorbed in the grooves. Whole and dissociated dorsal root ganglia were seeded on the substrates and neurite outgrowth and alignment along the microgrooves were measured. The microgrooves provide physical guidance, whereas laminin provides chemical cues to the neurons. The groove depth and spacing ...


Micropatterned Schwann Cell-Seeded Biodegradable Polymer Substrates Significantly Enhance Neurite Alignment And Outgrowth, Cheryl Miller, Srdija Jeftinija, Surya K. Mallapragada Jan 2001

Micropatterned Schwann Cell-Seeded Biodegradable Polymer Substrates Significantly Enhance Neurite Alignment And Outgrowth, Cheryl Miller, Srdija Jeftinija, Surya K. Mallapragada

Chemical and Biological Engineering Publications

Biomimetic strategies were employed to promote directional outgrowth of neurites in vitro by using a synergistic combination of physical, chemical, and cellular cues. Compression molded and solvent cast biodegradable polymer substrates made of poly(D,L-lactic acid) were micropatterned to form grooves on the substrate surfaces. Laminin was localized in the grooves, and rat sciatic Schwann cells were seeded on the substrates. Whole as well as dissociated rat dorsal root ganglia were seeded on the substrates along with Schwann cells, and neurite outgrowth and alignment were measured. The micropatterns provide physical guidance, laminin provides chemical cues, and the Schwann cells ...


A Quantitative Method Of Measuring Cell-Substrate Adhesion Areas, R. G. Richards, G. Rh Owen, B. A. Rahn, I. Ap Gwynn Jan 1997

A Quantitative Method Of Measuring Cell-Substrate Adhesion Areas, R. G. Richards, G. Rh Owen, B. A. Rahn, I. Ap Gwynn

Cells and Materials

Variability in measurements of the 'cell adhesion strength' of fibroblasts to substrates using mechanical disruption techniques causes difficulty in determining precisely the position, in the cytoskeleton-focal adhesion-matrix -substrate interface, where failure has occurred. In the present study, a quantitative in vitro procedure for measuring the total area and percentage of fibroblast adhesion to biomaterials, using the scanning electron microscope (SEM), is described. The amount of adhesion ofL929 and Balb/c3T3 fibroblasts to discs of stainless steel, commercially pure titanium, and polyethylene terepthalate (Thermanox) was quantified. Cells were fixed, stained with heavy metals, dehydrated and embedded in resin. The resin blocks ...


Cell Adhesion To Crystal Surfaces: A Model For Initial Stages In The Attachment Of Cells To Solid Substrates, D. Hanein, B. Geiger, L. Addadi Jan 1995

Cell Adhesion To Crystal Surfaces: A Model For Initial Stages In The Attachment Of Cells To Solid Substrates, D. Hanein, B. Geiger, L. Addadi

Cells and Materials

This study addresses the mechanism of the chirally-restricted, ROD-independent adhesion of A6 epithelial cells to the {011} faces of calcium {R,R)-tartrate tetrahydrate crystals. The extensive and rapid adhesion of the cells to these surfaces, in the presence or absence of serum proteins, is distinctly different from the extracellular matrix-mediated adhesion to conventional tissue culture surfaces or to the {101} faces of the same crystals. The differences are manifested by insensitivity to ATP depletion, to disruption of microfilaments and microtubules and even to formaldehyde fixation of the cells. Furthermore, trypsin pretreatment does not affect cell attachment to the {011 ...


Quantitative Scanning Electron Microscopy (Sem) To Study The Adhesion And Spreading Of Human Endothelial Cells To Surface-Modified Poly(Carbonate Urethane)S, C. James Kirkpatrick, Tillmann Otterbach, Dirk Anderheiden, Johannes Schiefer, Horst Richter, Hartwig Hartwig Hocker, Christian Mittermayer, Albert Dekker Jan 1992

Quantitative Scanning Electron Microscopy (Sem) To Study The Adhesion And Spreading Of Human Endothelial Cells To Surface-Modified Poly(Carbonate Urethane)S, C. James Kirkpatrick, Tillmann Otterbach, Dirk Anderheiden, Johannes Schiefer, Horst Richter, Hartwig Hartwig Hocker, Christian Mittermayer, Albert Dekker

Cells and Materials

The polymers currently in use as vascular prostheses are, in the native state, poor substrates for endothelial cell (EC) adhesion and growth. This has a negative effect on the success of pre-seeding regimes. One attempt to improve the polymer substrate is to covalently couple reactive molecules to the surface, which can be used as anchorage points for EC or serve as spacer molecule to couple biological signal molecules such as oligopeptides. We have used a digitized image analysis system coupled to a scanning electron microscope to study the adhesion and spreading of human venous EC to unmodified poly(carbonate urethane ...


Image Enhancement And Analysis Of Leukocyte Adhesion, Yee-Ruh Lin May 1991

Image Enhancement And Analysis Of Leukocyte Adhesion, Yee-Ruh Lin

Theses

The image of leukocyte adhesion to microvascular walls in the isolated rat perfused heart model has been observed and processed. Some of the fluorescent labeled leukocytes are barely visible due to microscope focal plane and the motion of objects. The purpose of this thesis is to extract leukocyte from the image of the experimental data using image enhancement and analysis (segmentation) techniques and develop a program to handle automatically counting of leukocytes in a predefined scene.