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Articles 1 - 30 of 32
Full-Text Articles in Engineering
Identification Of Novel Genes Regulating Elastic Fiber Formation Through Expression Profiling Analysis Of Elastogenic Models, Erin Sproul
All Dissertations
Background: Particularly important to the mechanical performance of native arterial blood vessels is elastin, an extracellular matrix (ECM) protein deposited by VSMCs in the form of elastic fibers, arranged in concentric lamellae in the media of the vessel wall. In addition to serving as major structural elements of arterial walls, providing extensibility and elastic recoil, elastic fibers also influence vascular cell behaviors. For these reasons tissue engineers are attempting to exploit elastic fiber biology to enhance vascular graft design and patency. Therefore, developing a greater understanding of the molecular mechanisms of elastogenesis may offer opportunities to control elastogenesis in tissue …
In Vitro Simulation Of Pathological Bone Conditions To Predict Clinical Outcome Of Bone Tissue Engineered Materials, Duong Nguyen
In Vitro Simulation Of Pathological Bone Conditions To Predict Clinical Outcome Of Bone Tissue Engineered Materials, Duong Nguyen
All Dissertations
According to the Centers for Disease Control, the geriatric population of ≥65 years of age will increase to 51.5 million in 2020; 40% of white women and 13% of white men will be at risk for fragility fractures or fractures sustained under normal stress and loading conditions due to bone disease, leading to hospitalization and surgical treatment. Fracture management strategies can be divided into pharmaceutical therapy, surgical intervention, and tissue regeneration for fracture prevention, fracture stabilization, and fracture site regeneration, respectively. However, these strategies fail to accommodate the pathological nature of fragility fractures, leading to unwanted side effects, implant failures, …
Vascular Nanomedicine: Site Specific Delivery Of Elastin Stabilizing Therapeutics To Damaged Arteries, Aditi Sinha
Vascular Nanomedicine: Site Specific Delivery Of Elastin Stabilizing Therapeutics To Damaged Arteries, Aditi Sinha
All Dissertations
Elastin, a structural protein in the extra-cellular matrix, plays a critical role in the normal functioning of blood vessels. Apart from performing its primary function of providing resilience to arteries, it also plays major role in regulating cell-cell and cell-matrix interactions, response to injury, and morphogenesis. Medial arterial calcification (MAC) and abdominal aortic aneurysm (AAA) are two diseases where the structural and functional integrity of elastin is severely compromised. Although the clinical presentation of MAC and AAA differ, they have one common underlying causative mechanism--pathological degradation of elastin. Hence prevention of elastin degradation in the early stages of MAC and …
Biological Scaffolds For Peripheral Vascular Surgery, George Fercana
Biological Scaffolds For Peripheral Vascular Surgery, George Fercana
All Dissertations
The gold standards for small diameter peripheral vascular graft replacement are autologous arteries or veins; however, one-third of patients lack such vessels due to previous vessel harvesting or advanced vascular disease. A promising approach for patients in this category is tissue engineering with off-the-shelf biological vascular grafts. Three small diameter acellular scaffolds were developed and evaluated as vascular grafts. Porcine renal arteries (2-3 mm diameter, 20 mm length) were decellularized by immersion and stabilized with penta-galloyl glucose (PGG) with and without subsequent heparinization via carbodiimide chemistry. Bovine mammary (4-6 mm ID, 250 mm length) and femoral arteries (6-8 mm ID, …
Engineering Beta-Cell Spheroids For Type 1 Diabetes Treatment, Xiaoyan Liu
Engineering Beta-Cell Spheroids For Type 1 Diabetes Treatment, Xiaoyan Liu
All Dissertations
Diabetes mellitus, the third most common disease in the world, is a chronic metabolic disorder caused by a failure of insulin production and/or an inability to respond to insulin. Specifically, type 1 diabetes is a disorder characterized by targeted autoimmune-directed destruction of a patient's beta-cell population within the pancreatic islets of Langerhans. The current primary treatment for type 1 diabetes is daily multiple insulin injections. However, this treatment cannot provide sustained physiological release, and the insulin amount is not finely tuned to glycemia. Pancreatic transplants or islet transplants would be the preferred treatment method but the lack of donor tissue …
The Effects Of Different Size Gold Nanoparticles On Mechanical Properties Of Vascular Smooth Muscle Cells Under Mechanical Stretching, Tri Kieu
All Theses
The field of nanotechnology research has seen a large growth in the past few decades due to the great potential of novel nano-size material for useful applications such as drug delivery and medical imaging. Also, they are a promising platform for the detection of terrible diseases such as cancer and atherosclerosis. Although these materials hold great promise, there is very limited understanding about the biological effects of these nanoparticles on normal healthy cells, such as vascular smooth muscle cells (VSMCs). The VSMCs are unique cells due to the two distinct phenotype characteristics it can express: a contractile and a synthetic …
Development And Verification Of A Test System To Quantify Strain Of An Optical Displacement Indicator And The Design Of A Strain Indicating Prototype, Josh Lake
All Theses
The organic-rich Middle Devonian Marcellus Shale of the Appalachian basin is a rapidly developing natural gas play. Stratigraphic boundaries of the Marcellus Shale in Westmoreland County, Pennsylvania were identified using geophysical logs from 10 vertical gas-producing wells in a 23 sq. km area. Gamma-ray, bulk density, and resistivity well logs were examined to assess hydrocarbon potential. Values of porosity, total organic carbon (TOC), and water saturation (SW) were derived and mapped by incorporating well-log data into Marcellus-specific formulas. Gamma-ray, penetration (minutes per foot drilled), and mud-logging gas (total gas) from 12 horizontal wells from within the study area were also …
Scratch Damage Evolution On Metals In Total Joint Replacements, Caleb Eljach
Scratch Damage Evolution On Metals In Total Joint Replacements, Caleb Eljach
All Theses
The goal of total joint replacement (TJR) is to replace nonfunctioning joint components and relieve pain, improve quality of life, and to improve joint function. Although TJR is a successful procedure, more than 54,000 knee revisions occur each year due to factors, such as wear, loosening, infection, fracture, instability, and patient related factors (Ranawat, 2010). TJRs consist of components typically composed of polyethylene and a metallic counterface (Navarro, 2008). The sliding contact that occurs between the metal and polyethylene components has been well studied and is shown to produce both surface damage and wear of the implant components (Barbour, 1997; …
Interstitial Cell Seeding And Dynamic Conditioning Of Aortic Heart Valve Scaffolds, Allison Kennamer
Interstitial Cell Seeding And Dynamic Conditioning Of Aortic Heart Valve Scaffolds, Allison Kennamer
All Theses
In 2011, U.S. Markets for Heart Valve Repair and Replacement Products estimated that roughly four million people in the United States are diagnosed with a heart valve disorder annually. And in the following year, the American Heart Association reported that approximately 35,000 deaths in the US were either directly or indirectly attributed to heart valve disease. Diseases of the heart valve are degenerative in nature and therefore progressively worsen unbeknownst to the patient until symptoms become clinically relevant. By this time, the valve is in such poor condition that complete replacement is often the only effective treatment. Current solutions are …
Functional Stroke Recovery Through Tissue Engineered Niche Neural Constructs, Natasha Topoluk
Functional Stroke Recovery Through Tissue Engineered Niche Neural Constructs, Natasha Topoluk
All Theses
According to the Centers for Disease Control and Prevention, stroke is statistically responsible for 1 in every 19 deaths of American citizens.5 Stroke is the leading cause of permanent disability due to the fact that it compromises both cellular and tissue components of the brain, leading to the formation of a physical void within the tissue. Current research approaches address the cellular component by injecting stem cells into this void; however, extremely low cell engraftment, high injected cell death, and overall no matrix regeneration are observed. Additionally, these stem cells do not remain committed to a neural lineage. We propose …
A Novel Hybrid Hydrogel For Scaffold-Mediated Gene Delivery, Jeremy Zhang
A Novel Hybrid Hydrogel For Scaffold-Mediated Gene Delivery, Jeremy Zhang
All Dissertations
Scaffold-mediated nonviral gene delivery avoids several drawbacks of systemic injection such as clearance by the reticulo-endothelial system and serum aggregation. Existing synthetic and natural polymers used in gene delivery scaffolds are primarily derived from other tissue engineering applications with design parameters focused on the physicochemical properties of the scaffold and its biocompatibility. Common synthetic materials used in polymeric scaffolds such as PEG are practically bio-inert with minimal cell and protein interaction. Therefore, an opportunity exists for the rational design novel gene delivery scaffolds with components capable of increasing the expression of incorporated transgene by including scaffold components that interact with …
Feeling For Failure: Haptic Force Perception Of Soft Tissue Constraints In A Simulated Minimally Invasive Surgery Task, Lindsay Long
Feeling For Failure: Haptic Force Perception Of Soft Tissue Constraints In A Simulated Minimally Invasive Surgery Task, Lindsay Long
All Dissertations
In minimally invasive surgery (MIS), the ability to accurately interpret haptic information and apply appropriate force magnitudes onto soft tissue is critical for minimizing bodily trauma. Force perception in MIS is a dynamic process in which the surgeon's administration of force onto tissue results in useful perceptual information which guides further haptic interaction and it is hypothesized that the compliant nature of soft tissue during force application provides biomechanical information denoting tissue failure. Specifically, the perceptual relationship between applied force and material deformation rate specifies the distance remaining until structural capacity will fail, or indicates Distance-to-Break (DTB). Two experiments explored …
Biofabrication Of Scaffolds For Intervertebral Disc (Ivd) Tissue Regeneration, Benjamin Whatley
Biofabrication Of Scaffolds For Intervertebral Disc (Ivd) Tissue Regeneration, Benjamin Whatley
All Dissertations
The ultimate goal of tissue regeneration is to replace damaged or diseased tissue with a cell-based or biomaterial-based tissue that accurately mimics the functionality, biology, mechanics, and cellular and extracellular matrix (ECM) composition of the native tissue. Specifically, the ability to control the architecture of tissue engineered constructs plays a vital role in all of these issues as scaffold architecture has an affect on function, biomechanics, and cellular behavior. Many tissue engineered scaffolds focus on the ability to mimic natural tissue by simulating the ECM due to the fact that in each distinct tissue, the ECM serves as a structural …
Implantable Biosensors For Physiologic Status Monitoring During Hemorrhage, Christian Kotanen
Implantable Biosensors For Physiologic Status Monitoring During Hemorrhage, Christian Kotanen
All Dissertations
Trauma diagnostics and management are major aims of research for implantable amperometric enzyme biosensor technology. Biosensors are capable of monitoring metabolic variables in a minimally invasive manner and have great potential to augment current wireless vital sign monitoring technologies in order to make a more robust physiologic status monitoring platform. The dual responsive Electrochemical Cell-on-a-Chip Microdisc Electrode Array (ECC MDEA 5037) is a recently developed electrochemical transducer for use in a wireless, implantable biosensor system for the continuous measurement of interstitial glucose and lactate. Hyperglycemia arising from insulin resistance and hyperlactatemia arising from anaerobic metabolism both occur following trauma and …
Ion Channel-Mediated Hydrostatic Pressure Mechanotransduction In Urothelial Cells, Kevin Champaigne
Ion Channel-Mediated Hydrostatic Pressure Mechanotransduction In Urothelial Cells, Kevin Champaigne
All Dissertations
A majority of men and women aged 40 and over experience lower urinary tract symptoms, including urgency, incontinence, and frequency, which often affect the individual's quality of life. Although often considered a simple structure, the bladder is a complex system with sophisticated sensory and motor feedback mechanisms that allow for the sensation of fullness and pain, reflexive responses to bladder filling, and conscious control over the time and place of micturition. Although disruptions of these sensory mechanisms are believed to cause certain lower urinary tract dysfunctions, the specific mechanisms involved in sensing bladder fullness, distension, tension, or pressure at the …
Spatial Control Of Magnetic Nanoparticles Integrated With Cellular Spheroids As Tissue Engineered Building Blocks, Brandon Mattix
Spatial Control Of Magnetic Nanoparticles Integrated With Cellular Spheroids As Tissue Engineered Building Blocks, Brandon Mattix
All Dissertations
Magnetic nanoparticles (MNPs) have been investigated in tissue engineering applications to provide in situ imaging, drug delivery, and tissue patterning, but direct and prolonged interaction between cells and MNPs can have adverse effects on cell function. Therefore, methods which reduce or limit the interaction of MNPs with cells, or utilize more biocompatible MNP-based strategies will improve upon the commonly used iron oxide MNPs. We investigated a variety of methods to improve upon the use of MNPS in tissue engineering.
Cell aggregates, or spheroids, have been used as tissue engineered building blocks that can closely mimic the native three-dimensional in vivo …
The Development Of A Rapid Fiber-Based Immunoassay As A Point-Of-Care Or In-Home Diagnostic Test, Christopher Waddell
The Development Of A Rapid Fiber-Based Immunoassay As A Point-Of-Care Or In-Home Diagnostic Test, Christopher Waddell
All Theses
Early diagnosis of conditions allows for physicians to treat patients earlier, and ultimately improve patient outcomes. Two conditions of particular interest for earlier and cheaper diagnosis are the influenza virus and human immunodeficiency virus (HIV). Antiviral treatment administered within the first 48 hours of influenza infection decreases symptom severity, risk of complications, and reduced healthcare costs. Early diagnosis of HIV can decrease the risk of transmission of the virus to HIV negative individuals and allow for earlier administration of highly active antiretroviral treatment (HAART), improving patient quality of life and patient outcomes.
Currently, the 'gold standard' for detection of both …
Problems In The Study And Use Of Ac Dielectrophoresis And Their Consequences: A Study Based On Comsol Multiphysics Modeling, Vandana Devi Pandian Babu
Problems In The Study And Use Of Ac Dielectrophoresis And Their Consequences: A Study Based On Comsol Multiphysics Modeling, Vandana Devi Pandian Babu
All Theses
Dielectrophoresis (or DEP) is an important phenomenon which is induced when a dielectric particle is placed in a non-uniform electric field. The force generated by DEP has been exploited for various micro and nano fluidics applications like positioning, sorting and separation of particles involved in medical diagnostics, drug discovery, cell therapeutics, biosensors, microfluidics, nanoassembly, particle filtration etc. The integration of DEP systems into the microfluidics enables inexpensive, fast, highly sensitive, highly selective, label-free detection and also the analysis of target bioparticles.
This work aims to provide a complete compilation of the factors affecting the DEP force. It elucidates the underlying …
Experimental Development And Analysis Of A Novel Setup For Insulated Dielectrophoresis, Johnie Hodge
Experimental Development And Analysis Of A Novel Setup For Insulated Dielectrophoresis, Johnie Hodge
All Theses
Dielectrophoresis has long been studied and utilized for the manipulation of microscale particles in solution. This phenomenon is due to the induced polarization of dielectric particles subjected to an electric field. When the field is also inhomogeneous in terms of the distribution of its strength through space, the polarized particles move and come to rest in certain areas due to the relationship between their and the solvent's relative permittivities. If the electric field is homogenous, such as within a parallel plate capacitor, the particles are polarized according to their permittivity and the field's frequency, but they will not move.
These …
Extraction Of Antioxidants From Animal Blood And Its Potential Application As A Pet Food Preservative, Chengyi Tu
Extraction Of Antioxidants From Animal Blood And Its Potential Application As A Pet Food Preservative, Chengyi Tu
All Theses
Nowadays, more and more people are having pets as members of their family. To the year of 2012, there are 78.2 million dogs and 86.4 million cats owned in the U.S according to the report of the Humane Society of the U.S. The pet food industry as a result has been prosperous, with an estimated market size of $21 billion in the year of 2013. However, there is a common problem for the industry - fat rancidification. Pet foods usually contain relatively high levels of fat, which, if not well protected, are prone to oxidation and generate unfavorable products including …
Multifunctional Nanophosphors For Tissue Imaging And Drug Delivery, Hongyu Chen
Multifunctional Nanophosphors For Tissue Imaging And Drug Delivery, Hongyu Chen
All Dissertations
X-rays have been used for non-invasive high-resolution imaging of thick biological specimens since their discovery in 1895. They are widely used for structural imaging of bone, metal implants, and cavities in soft tissue. Recently, a number of new contrast methodologies have emerged which are expanding X-ray's biomedical applications to functional as well as structural imaging. However, traditional X-ray imaging provides high spatial resolution imaging through tissue but do not measure chemical concentrations. In this dissertation, we describe an X-ray excited optical luminescence (XEOL) technique which uses a scanning X-ray beam to irradiate Gd2O2S phosphors and detect the resulting visible luminescence …
Sustained Release Of Estrogens From Pegylated Nanoparticles For Treatment Of Secondary Spinal Cord Injury, John Barry
Sustained Release Of Estrogens From Pegylated Nanoparticles For Treatment Of Secondary Spinal Cord Injury, John Barry
All Dissertations
Spinal Cord Injury (SCI) is a debilitating condition which causes neurological damage and can result in paralysis. SCI results in immediate mechanical damage to the spinal cord, but secondary injuries due to inflammation, oxidative damage, and activated biochemical pathways leading to apoptosis exacerbate the injury. The only currently available treatment, methylprednisolone, is controversial because there is no convincing data to support its therapeutic efficacy for SCI treatment. In the absence of an effective SCI treatment option, 17β-estradiol has gained significant attention for its anti-oxidant, anti-inflammatory, and anti-apoptotic abilities, all events associated with secondary. Sadly, 17β-estradiol is associated with systemic adverse …
Evaluating Mechanical Performance Of Hydrogel-Based Adhesives For Soft Tissue Applications, Nitin Balakrishnan
Evaluating Mechanical Performance Of Hydrogel-Based Adhesives For Soft Tissue Applications, Nitin Balakrishnan
All Theses
According to the National Center for Health Statistics, an estimated 22 million women have undergone a hysterectomy procedure in the United States. The most common complication during hysterectomies is accidental laceration of the urinary bladder during the surgery with incidence between 0.2-8.3% with the current gold standard wound repair method being sutures. Yet, sutures come with their own limitations in that they necessitate use of a catheter and collection bag during healing due to preventing proper distention of the bladder tissue at normal pressures. The long-term goal of our study is to eliminate the need for suturing by creating a …
Evaluation Of Angular Velocity Data From Inertial Measurement Units For Use In Clinical Settings, Chelsea Ex-Lubeskie
Evaluation Of Angular Velocity Data From Inertial Measurement Units For Use In Clinical Settings, Chelsea Ex-Lubeskie
All Theses
Evaluating the human gait cycle with inertial measurement units (IMU) may prove beneficial for applications such as diagnoses of musculoskeletal diseases and assessment of rehabilitation regimes. An IMU system is potentially applicable for diagnosing and assessing rehabilitation outcomes for a variety of neuromuscular diseases since it is small, portable, and less expensive than a camera system. IMUs directly measure angular velocity, whereas position data from a camera system must be processed twice to obtain this information. The purpose of this research is to determine repeatability of IMU angular velocity data, and agreement between angular velocity data from an IMU system …
Highly Sensitive Fiber-Based Devices For Gene And Protein Analysis, Victor Maximov
Highly Sensitive Fiber-Based Devices For Gene And Protein Analysis, Victor Maximov
All Dissertations
Single cell probing has found a number of applications in different areas of research. It can help us to better understand cell-to-cell interactions; it has found numerous applications in immunology, cancer research, detection of pathogenic infections and genetic abnormalities. The single cell analysis is very important in stem cells research and development of cells. The main obstacle in the single cell analysis is the small amount of analyte that a single cell could provide. Another difficulty is connected to the cell-to-cell variability inside the uniform population due to the differences of single cells in size, activity, mitotic stage, and functions. …
Development Of An Ex Vivo Tissue Testing System For Three Dimensional Biomechanical Analysis Of Abdominal Aortic Aneurysm, Bradley Johns
Development Of An Ex Vivo Tissue Testing System For Three Dimensional Biomechanical Analysis Of Abdominal Aortic Aneurysm, Bradley Johns
All Theses
Abdominal aortic aneurysms (AAA) are localized, progressive dilations of the aortic wall and are the 13th most common cause of death in the United States (~15,000 per year) and surgery is usually recommended when the aneurysm is 5 cm or larger in diameter. Because of this clinical parameter, previous studies of AAA biomechanics have utilized a one-dimensional analysis that focuses solely on changes in wall diameter and have attempted to model geometric changes with mathematical formulas, generally based on the LaPlace equation. This is not sufficient however, as the mechanical behavior of the tissue at sites of aneurysm have been …
A Regenerative Medicine Approach To Improved Tendon Healing And Repair, Grace Margaret Dion
A Regenerative Medicine Approach To Improved Tendon Healing And Repair, Grace Margaret Dion
All Theses
Surgical repair of torn tendons is a common orthopaedic procedure in the United States, with nearly 400,000 repairs occurring annually. Despite improvements in surgical techniques used to re-attach the tendon to its boney insertion, clinically successful outcomes amongst patients are variable and re-tear rates can be exceedingly high. The use of stem cells as an adjunct to surgical repair to aid in improving tendon healing and repair strength has gained much interest amongst the clinical community. Accordingly, many investigators have begun examining the ability of stem cells to differentiate into tenocytes using various methodologies including the application of growth factors …
Characterization Of Potential Wear Sources In Knee Arthroplasty Prostheses After In Vivo Function, Nicole Durig
Characterization Of Potential Wear Sources In Knee Arthroplasty Prostheses After In Vivo Function, Nicole Durig
All Theses
Total joint arthroplasty (TJA) is a common procedure generally performed in patients with osteoarthritis. While TJA continues to be a successful treatment for degenerative joint disease, there are many studies that demonstrate wear and its sequelae as the major limitation of joint replacement longevity. Previous studies have shown that wear debris originates from four main locations: articulating surfaces, modular component surfaces, surfaces of fixation, and adjuvant fixation devices. Each of these possible wear sources can initiate the cascade of failure associated with wear-induced osteolysis and lead to subsequent revision surgery. The objective of this thesis is to characterize the in …
Post-Market Surveillance Of Total Knee Replacement Combining Clinical Outcomes And Quantitative Image Processing Techniques, Leah Nunez
All Theses
Total knee replacement (TKR) is a successful procedure for the relief of pain, correction of deformity, and restoration of function in patients with knee arthritis.1-3 In the United States, the number of primary TKR surgeries performed in 2030 is projected to be between 2,938,000 to 4,136,000 and revision surgeries between 193,000 to 381,000.4 Osteolysis, pain, and aseptic loosening are the most common causes of revision TKR surgery.5 The purpose of this thesis is to complete assessments for post-market surveillance of total knee replacement (TKR) targeting areas for improving polymer bearings through evaluation of clinical outcomes and analysis of prosthesis retrieved …
Dynamic Transcriptional Response Of Escherichia Coli To Inclusion Body Formation, Faraz Baig
Dynamic Transcriptional Response Of Escherichia Coli To Inclusion Body Formation, Faraz Baig
All Theses
Escherichia coli is used intensively for recombinant protein production due to its many unique advantages, but one key challenge with the use of E. coli is the tendency of recombinant proteins to misfold and aggregate into insoluble inclusion bodies (IBs). The presence of IBs stresses cells and can hinder overall growth. Additionally, IBs contain high concentrations of recombinant protein in an inactive form and thus require recovery steps to salvage functional recombinant protein. Currently, no universally effective method exists to prevent IB formation in recombinant E. coli. Further research into the gene expression response to insoluble recombinant protein may …