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Full-Text Articles in Engineering

The Development Of Hyaluronic Acid Biomaterials For Vascular Tissue Engineering, Samir Ibrahim Dec 2008

The Development Of Hyaluronic Acid Biomaterials For Vascular Tissue Engineering, Samir Ibrahim

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Current vascular implant materials poorly interact with medial smooth muscle cells (SMCs) allowing the permanent loss of vascular elastin, eliminated by trauma or disease, a crucial element in maintaining the natural biomechanics of the blood vessel and overall vascular homeostasis. In addition, these materials insufficiently recruit vascular endothelial cells (ECs) to form a normally functional, confluent endothelium that acts as the interface between the blood and vascular tissue and regulates numerous vital vascular processes. As a result, the restenosis, or re-occlusion, rate within these devices has remained fairly high stimulating the investigation of numerous new materials capable of providing the …


Effect Of Clinically Relevant Mechanical Forces On Smooth Muscle Cell Response In Model Of Balloon Angioplasty, Kara Acampora Dec 2008

Effect Of Clinically Relevant Mechanical Forces On Smooth Muscle Cell Response In Model Of Balloon Angioplasty, Kara Acampora

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Restenosis remains a common problem affecting the patency of endovascular intervention such as balloon angioplasty and stent placement as treatments for atherosclerosis. Denudation of the endothelial layer and the increased injury from balloon deployment can cause phenotypic changes in surrounding vascular smooth muscle cells (SMCs) in vivo. The presented work modeled this mechanical environment in vitro to investigate the role of the altered mechanical environment on the phenotypic response of SMCs. Through the system design and CFD channel characterization, a six-independent-channel system providing low oscillating wall shear stress (WSS) was manufactured to apply concurrent shear and tensile forces with uniform …


Human Microvasculature Fabrication Using Thermal Inkjet Printing Technology, Xiaofeng Cui Dec 2008

Human Microvasculature Fabrication Using Thermal Inkjet Printing Technology, Xiaofeng Cui

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The current tissue engineering paradigm is that successfully engineered thick tissues must include vasculature. As biological approaches alone such as VGEF have fallen short of their promises, one may look for an engineering approach to build microvasculature. With the advent of cell printing, one may be able to build precise human microvasculature with suitable bio-ink. Human Microvascular Endothelial Cells (HMVEC) and fibrin were studied as bio-ink for microvasculature construction. Endothelial cells are the only cells to compose the human capillaries and also the major cells of blood vessel intima layer. Fibrin has been already widely recognized as tissue engineering scaffold …


Characterization Of Vascular Smooth Muscle Cell Mechanical And Frictional Properties Using Atomic Force Microscopy, Jason Hemmer Dec 2008

Characterization Of Vascular Smooth Muscle Cell Mechanical And Frictional Properties Using Atomic Force Microscopy, Jason Hemmer

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A working hypothesis within the Laboratory of Vascular Research is that mechanical loading on vascular smooth muscle cells (VSMCs), especially due to solid contact from endovascular devices, contributes to the development of restenosis. In order to better understand the role of mechanical loading on VSMCs in vascular disease development, it is imperative to understand the mechanical properties of VSMCs themselves. To measure the viscoelastic and frictional properties of living VSMCs in an in vitro setting, an atomic force microscope (AFM) was utilized, thereby allowing for mechanical testing of living cells in a fluid environment. In the first phase of research, …


Vascular Tissue Engineering: The Creation Of Living, Non-Thrombogenic, Functional Blood Vessels Based On Elastin Scaffolds, Aditee Kurane Dec 2008

Vascular Tissue Engineering: The Creation Of Living, Non-Thrombogenic, Functional Blood Vessels Based On Elastin Scaffolds, Aditee Kurane

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Cardiovascular diseases are the leading cause of death worldwide. Blood vessel replacement is a common treatment for vascular diseases such as atherosclerosis, restenosis and aneurysm, with over 300,000 bypass procedures performed each year. However, vein grafts are limited due to their availability. Although synthetic vascular replacements have been successful for large diameter arteries, they have shown minimal success in arteries with diameters <6mm. This is because most synthetic materials induce thrombus formation which, within a few months of implantation, causes failure of the vascular graft due to occlusion. Tissue engineering is a promising approach to the fabrication of non-thrombogenic vascular grafts, but a reliable and expandable cell source for tissue-engineered vascular graft (TEVG) has not been established.
The work presented here is motivated by the current unavailability of an ideal tissue engineered blood vessel replacement. Our overall goal is to create a living tissue engineered vascular graft that is biodegradable, non-thromobogenic, presents low antigenicity and …


Ecm Stabilization Strategies For Bioprosthetic Heart Valves For Improved Durability, Devanathan Raghavan Dec 2008

Ecm Stabilization Strategies For Bioprosthetic Heart Valves For Improved Durability, Devanathan Raghavan

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Abstract
Approximately 85,000 heart valve replacement surgeries are performed every year in United States and about 300,000 surgeries worldwide. It is estimated that half of them are mechanical valve replacements and the other half bioprosthetic valve replacements. The use of bioprosthetic heart valves is slowly increasing. Bioprosthetic heart valves are made from porcine aortic valves or bovine pericardium. Commercially these bioprostheses are currently crosslinked using glutaraldehyde (GLUT) to prevent tissue degradation and reduce tissue antigenicity. GLUT crosslinks these bioprostheses by stabilizing the collagen present in the tissue via a Schiff base reaction of the aldehyde with the hydroxylysine / lysine …


The Spaceflight Environment And The Skeletal System, Eric Bandstra Aug 2008

The Spaceflight Environment And The Skeletal System, Eric Bandstra

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The spaceflight environment presents many challenges to the human body. Bone loss in astronauts is a well known consequence of reduced loading in the weightless environment of low-earth orbit. Recent studies have also indicated that spaceflight relevant types of radiation (at relatively high doses) have deleterious effects on trabecular bone. Both of these represent potential skeletal challenges during long-duration spaceflight. The objective of these studies is to examine the response of bone to models of the spaceflight environment.
Astronauts will likely absorb doses of protons and heavy ions during lengthy missions outside the Earth's magnetosphere. Following exposure to a range …


Chitosan Derivatives For Tissue Engineering, Yongzhi Qiu Aug 2008

Chitosan Derivatives For Tissue Engineering, Yongzhi Qiu

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Chitosan, a naturally occurring polysaccharide, and its derivatives have been widely explored for biomedical applications due to their biocompatibility and biodegradability. In our studies, we developed a series of chitosan derivatives through chemical modifications. These chitosan derivatives not only possess better processibility in scaffolds fabrication, but also show excellent potentials in tissue engineering applications, including blood vessel and bone tissue engineering.
The excellent antithrombogenic property is crucial for vascular engineering applications, especially in engineering small-diameter blood vessels. In our studies, chitosan was chemically modified by phthalization and the phthalized chitosan exhibited great antithrombogenic property. Through a wet- phase-inversion process, tubular …


Engineered Micro-Environments And Vibrational Culture Systems For Vocal Fold Tissue Engineering, Jaishankar Kutty Aug 2008

Engineered Micro-Environments And Vibrational Culture Systems For Vocal Fold Tissue Engineering, Jaishankar Kutty

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Voice is produced by the conversion of aerodynamic energy from exhalation to acoustical energy for voice production by the vocal folds (membranous connective tissue) located in the larynx. The quality of voice depends on the biomechanical properties of the multi-layered vocal fold tissue which derive from its extracellular matrix (ECM) organization and composition. The wound healing response to vocal fold injuries is characterized by scarring and subsequent dysphonia due to alterations in the biomechanical properties of the tissue.
The work presented here is motivated by the importance of voice in maintaining quality of life and the inability of current treatment …


Cues For Cellular Assembly Of Vascular Elastin Networks, Chandrasekhar Kothapalli Aug 2008

Cues For Cellular Assembly Of Vascular Elastin Networks, Chandrasekhar Kothapalli

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Elastin, a structural protein distributed in the extracellular matrix of vascular tissues is critical to the maintenance of vascular mechanics, besides regulation of cell-signaling pathways involved in injury response and morphogenesis. Thus, congenital absence or disease-mediated degradation of vascular elastin and its malformation within native vessels due to innately poor elastin synthesis by adult vascular cells compromise vascular homeostasis. Current elastin regenerative strategies using tissue engineering principles are limited by the progressive destabilization of tropoelastin mRNA expression in adult vascular cells and the unavailability of scaffolds that can provide cellular cues necessary to up-regulate elastin synthesis and regenerate faithful mimics …


Assessment Of Fifth Metatarsal Etiology, Daniel Reed Jul 2008

Assessment Of Fifth Metatarsal Etiology, Daniel Reed

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The fifth metatarsal 'Jones Fracture' is a fracture that occurs 3.5cm distal to the tuberosity. It is an injury that is common in athletes, especially those who participate in sports with a lot of lateral movement. The Jones Fracture is known for its difficulty to heal due to non-union and re-fracture. There has been much research recently regarding in-shoe pressure distributions and their relation to shoe type, movement, and shoe surface interaction. However, only the forces along the bottom of the foot have been investigated. Literature and the direction of fracture seem to implicate a force on the lateral portion …


Risedronate Prevents Early Bone Loss Resulting From Whole-Body Irradiation, Eric Livingston Jul 2008

Risedronate Prevents Early Bone Loss Resulting From Whole-Body Irradiation, Eric Livingston

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Osteoporosis is a condition characterized by a reduction in bone strength resulting in an overall increase in the risk of fracture. There are many factors that contribute to the development of this condition, including ionizing radiation exposure. Declines in bone volume and trabecular micro-architecture have been found following exposure to multiple types of radiation. Past research has implicated reduction of osteoblast function and changes to vasculature as the primary sources of bone deterioration. Recently, an early increase in osteoclast number was observed following exposure to low-energy X-rays, identifying an increase in resorption as a possible cause and potential target for …


Biomechanical Evaluation Of Two Methods Of Humeral Shaft Fixation, Joshua Catanzarite Jul 2008

Biomechanical Evaluation Of Two Methods Of Humeral Shaft Fixation, Joshua Catanzarite

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Biomechanical evaluations of fracture fixation devices attempt to determine implant performance by approximating the in vivo conditions. This performance is affected by many factors and relies on the complex bone-implant interface. Biomechanical tests can be designed in a variety of ways in order to evaluate device performance with respect to any number of these bone-implant interactions. Standardized tests, designed by groups such as the American Society for Testing and Materials (ASTM), are often designed either to determine the performance of a specific type of fixation device or for direct comparison between different devices. Additionally, many biomechanical evaluations are designed for …


Quantifying Antalgic Gait Knee Function Using Inertial Sensor Technology, William Mostertz Jul 2008

Quantifying Antalgic Gait Knee Function Using Inertial Sensor Technology, William Mostertz

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The use of body-fixed inertial sensors to analyze human movement may prove useful in the medical field. Improving orthopaedic device design, diagnosing musculoskeletal disorders, and rehabilitation assessment could all benefit from a mobile gait analysis system based on inertial sensors. More specifically, patients recovering from lower limb corrective surgeries tend to adjust gait patterns to accommodate pain, a condition referred to as antalgic gait. Currently there is no quantitative method available to assess recovery for this patient population during post-operative management. A comparison of the inertial sensor system with the camera-based industry standard has confirmed it as a viable method …


Radiation-Induced Osteoporosis: Bone Quantity, Architecture, And Increased Resorption Following Exposure To Ionizing Radiation, Jeffrey Willey May 2008

Radiation-Induced Osteoporosis: Bone Quantity, Architecture, And Increased Resorption Following Exposure To Ionizing Radiation, Jeffrey Willey

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Skeletal complications from radiation therapy have been described for breast, brain, pelvic, and blood cancers. These problems include atrophy, fractures, and osteoradionecrosis. Improved survivorship rates of cancer patients receiving radiotherapy increases the importance of understanding the causal mechanisms and long-term effects of radiation-induced bone loss. One such long-term effect is bone fractures following radiation therapy for cancer treatment. The incidence of hip fractures is significantly increased following targeted radiotherapy for cancer. This decline in bone health can have a severe impact on the patient's functional capabilities. This damage to bone following irradiation is thought to involve damage to both osteoblasts …


Study Of Electrospinning Of Property-Modulated Biomedical Microfibers, Scott Taylor May 2008

Study Of Electrospinning Of Property-Modulated Biomedical Microfibers, Scott Taylor

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Electrospinning technologies have been of great interest in recent years, due in large part to developments in the field of Bioengineering, including the preparation of novel polymers and advances in tissue engineering, specifically for therapeutic applications. The electrospinning process is, in general, a very benign process that allows the preparation, under mild conditions, of micro- and nano-scale fibers from fiberforming materials, as well as traditionally non-fiber forming materials. This process is of specific interest to the biomedical community because it affords an opportunity to create highly-tailored novel constructs with a multitude of possible uses. Some proposed uses for these materials …