Biomedical Engineering and Bioengineering Commons^™

Modeling And Simulation Methodologies For Spinal Cord Stimulation., Saliya Kumara Kirigeeganage

Electronic Theses and Dissertations

The use of neural prostheses to improve health of paraplegics has been a prime interest of neuroscientists over the last few decades. Scientists have performed experiments with spinal cord stimulation (SCS) to enable voluntary motor function of paralyzed patients. However, the experimentation on the human spinal cord is not a trivial task. Therefore, modeling and simulation techniques play a significant role in understanding the underlying concepts and mechanics of the spinal cord stimulation. In this work, simulation and modeling techniques related to spinal cord stimulation were investigated. The initial work was intended to visualize the electric field distribution patterns in …

Rotary Pump Speed Modulation To Produce Pulsatile Flow And Ventricular Volume Unloading., Connor Joseph Smith

Electronic Theses and Dissertations

Background: Continuous-flow (CF) left ventricular assist devices (LVADs) have gained widespread clinical acceptance as a treatment option for advanced heart failure (HF); however, they have also been associated with an increased risk of adverse events, including gastrointestinal bleeding, aortic insufficiency, and hemorrhagic stroke. It has been hypothesized that the increase in adverse event incidence may be due in part to diminished vascular pulsatility and high shear stress when CF-LVADs are operated at fixed speeds. Previous studies have shown that pump speed modulation generates greater levels of pulsatility in rotary pumps than when operated at fixed speeds. The objective of this …

Evaluation Of Drug-Loaded Gold Nanoparticle Cytotoxicity As A Function Of Tumor Tissue Heterogeneity., Hunter Allan Miller

Electronic Theses and Dissertations

The inherent heterogeneity of tumor tissue presents a major challenge to nanoparticle-medicated drug delivery. This heterogeneity spans from the molecular to the cellular (cell types) and to the tissue (vasculature, extra-cellular matrix) scales. Here we employ computational modeling to evaluate therapeutic response as a function of vascular-induced tumor tissue heterogeneity. Using data with three-layered gold nanoparticles loaded with cisplatin, nanotherapy is simulated with different levels of tissue heterogeneity, and the treatment response is measured in terms of tumor regression. The results show that tumor vascular density non-trivially influences the nanoparticle uptake and washout, and the associated tissue response. The drug …

The Effectiveness Of Localized Ultrasound And Aptamer Surface Modification On Nanoemulsions For Drug Delivery To Spheroids., Daniel A. Hodge

Electronic Theses and Dissertations

Cancer is a group of diseases that affects 1.6 million and kills nearly 600,000 Americans each year. The National Cancer Institute defines it as “diseases in which abnormal cells divide without control and can invade nearby tissues” and it is often treated with one or more of the following: chemotherapy, radiation, surgery. The expense for these treatments is expected to rise to $156 billion by 2020. Localized delivery can improve effectiveness and cancer survival rates, decrease the cost of treatment, and decrease the side effects of chemotherapy. This paper addresses models for this localized delivery through nanoemulsions. Nanoemulsions are a …

Investigating The Likelihood Of Pediatric Femur Fracture Due To Falls Through Finite Element Analysis., Keyonna Mckinsey

Electronic Theses and Dissertations

Bone fracture is the second most common injury of child abuse. Studies have generally reported that femur fractures are more likely due to abuse than accidental causes in cases where the child is non-ambulatory. They have also found that household falls are commonly offered as the cause of injury in cases of abuse. In this study, a finite element (FE) pediatric femur model will be developed and used to evaluate likelihood of fracture in common household fall scenarios (bed falls and feet first falls). This will provide greater biomechanical evidence as to the likelihood of femur fracture due to common …

Investigation Of Cardiovascular Tissue Following 56fe-Radiation And Potential Countermeasure Effectiveness., Alexandra R Decarlo

Electronic Theses and Dissertations

Exposure to ionizing radiation is an important medical concern because it can lead to health problems including cancer and cardiovascular issues. In space, astronauts are exposed to ionizing radiation that is not experienced by those who remain on Earth. This radiation can cause health problems such as cardiovascular disease. One way this can happen is through the creation of reactive oxygen species, which can activate TGF-β1, contributing to fibrosis or other cardiovascular problems. Antioxidants can be a potential pharmacological mitigator of these excess reactive oxygen species because of their ability to neutralize reactive oxygen species. One such antioxidant with potential …

Plga-Modified Nanoparticles For The Treatment Of Hypo-Vascularized Hpv-Related Cervical Cancers., Lee B. Sims

Electronic Theses and Dissertations

A major challenge associated with delivery of active agents in the female reproductive tract (FRT) is the ability of agents to efficiently diffuse through the cervicovaginal mucosa (CVM) and reach the underlying sub-epithelial immune cell layer and vasculature. A variety of drug delivery vehicles have been employed to improve the delivery of agents across the CVM and offer the capability to increase the longevity and retention of active agents to treat infections of the female reproductive tract. Nanoparticles (NPs) have been shown to improve retention, diffusion, and cell-specific targeting via specific surface modifications, relative to other delivery platforms. In particular, …

Longitudinal Tracking Of Physiological State With Electromyographic Signals., Robert Warren Stallard

Electronic Theses and Dissertations

Electrophysiological measurements have been used in recent history to classify instantaneous physiological configurations, e.g., hand gestures. This work investigates the feasibility of working with changes in physiological configurations over time (i.e., longitudinally) using a variety of algorithms from the machine learning domain. We demonstrate a high degree of classification accuracy for a binary classification problem derived from electromyography measurements before and after a 35-day bedrest. The problem difficulty is increased with a more dynamic experiment testing for changes in astronaut sensorimotor performance by taking electromyography and force plate measurements before, during, and after a jump from a small platform. A …

Design And Development Of A Multifunctional Surgical Device For Ground And Space-Based Surgical Applications., Brooke Elaine Barrow

Electronic Theses and Dissertations

With the possibility of longer ventures into space, NASA will face many new medical challenges. The ability to surgically treat trauma and other disorders in reduced gravity requires reliable wound access, containment, and visualization. In collaboration with Carnegie Mellon University, the University of Louisville is currently developing the AISS (Aqueous Immersion Surgical System) to increase efficiency and control of the operative field in space-based surgeries. Reliable wound access and containment is achieved by placing a transparent wound-isolation dome securely over the wound-site and pressurizing it with a saline solution. Leak-free trocars provide access ports for various surgical instruments. This system …

Materials Design With Polylactic Acid-Polyethylene Glycol Blends Using 3d Printing And For Medical Applications., Jeremiah R. Bauer

Electronic Theses and Dissertations

This thesis is an examination of two material systems derived from polylactic acid (PLA) and polyethylene glycol (PEG). PLA is a polymer commonly sourced from renewable sources such as starches and sugars. It is a relatively strong, biodegradable polymer, making it ideal for use in the body. Even though it has a relative high strength, PLA is also brittle leading to the use of plasticizers to increase flexibility. One such plasticizer is PEG, which is a material that can exist at room temperature as either a thin liquid, or a hard waxy solid depending on the molecular weight. The first …

Tumor-Targeted Double Emulsions For Ultrasound-Triggered Delivery Of Molecular Therapeutics., Connor S Centner

Electronic Theses and Dissertations

Cancer is the second leading cause of death in the United States, with 1.74 million new cancer cases diagnosed and 610,000 cancer deaths expected in 2018 alone. Current treatments often result in negative systemic effects and ineffective treatment of the tumor. Drug delivery vehicles have been developed for more effective local delivery methods, but many drug delivery vehicles lack spatial and temporal control. Targeted double emulsions are a new class of drug delivery vehicles which present a promising option for a high payload and controlled delivery. The purpose of our project was to develop and characterize an aptamer-chelated double emulsion …

Probing The Effects Of Substrate Stiffness On Astrocytes Mechanics, Ariege Bizanti

Electronic Theses and Dissertations

Astrocytes are among the most functionally diverse population of cells in the central nervous system (CNS) as they are essential to many important neurological functions including maintaining brain homeostasis, regulating the blood brain barrier, and preventing build-up of toxic substances within the brain, for example. Astrocyte importance to brain physiology and pathology has inspired a host of studies focused on understanding astrocyte behavior primarily from a biological and chemical perspective. However, a clear understanding of astrocyte dysfunction and their link to disease has been hampered by a lack of knowledge of astrocyte behavior from a biomechanical perspective. Furthermore, astrocytes (and …

Development Of Low Frequency Electron Paramagnetic Resonance Methods And Instrumentation For Biological Applications, Laura A. Buchanan

Electronic Theses and Dissertations

EPR is a powerful biophysical tool that can be used to measure tumor physiology. With the addition of magnetic field gradients, the spectral properties of paramagnetic species can be mapped. To facilitate EPR imaging, methods and instrumentation at frequencies between 250 MHz and 1 GHz were developed.

At low spin concentrations, the rapid scan background signal is often many times larger than the EPR signal of interest. To help remove the background contribution, a data acquisition procedure that takes advantage of a cross-loop resonator and bipolar power supplies was developed at 250 MHz. In this procedure, two scans are collected. …

Optimization Of Plga And Plga-Dasatinib Particles Through A Taguchi Design Approach, Rayeanne N Balgemann

Electronic Theses and Dissertations

Proliferative vitreoretinopathy (PVR) is a disease of the retina in the human eye. Retinal pigment epithelium cells (RPE) undergo an epithelial to mesenchymal transition in response to retinal trauma. This transition gives the cells mobility and allows them to potentially infiltrate the vitreous chamber and deposit on either side of the retina. Once cell deposition has occurred, along with several other transformed cells derived from cell types such as Müller glia, these migratory cells can form a membrane contiguous with the retinal extracellular matrix and, upon contraction, cause wrinkling of the retina. If left untreated PVR can lead to traction …

Lcd 3d Printing Of A Photocurable Elastomer For Tissue Engineering, Beatriz Luiza De Souza

Electronic Theses and Dissertations

Three-dimensional scaffolding is an emerging research area in biomedical and tissue engineering. Scaffolds provide the possibility of growing tissues in a controlled environment, with desired characteristics and properties towards a specific application. A new method to 3D print biodegradable and biocompatible material called Polyglycerol Sebacate Acrylate (PGSA) is demonstrated. PGSA is essentially an acrylated form of PGS using photoinitiator to become a photocurable resin suitable for liquid crystal display (LCD) 3D printing. PGSA was selected because its rheological and crosslinking behavior (and hence its mechanical properties) can be controlled by changes in curing time, temperature, and pressure. This material has …

Computational Modeling Of Transcatheter Aortic Valves, Mostafa Abbasi

Electronic Theses and Dissertations

Transcatheter aortic valve replacement (TAVR) is an established therapy alternative to surgical valve replacement in high-risk and intermediate-risk patients with severe aortic stenosis. Currently, although TAVR is an alternative and less-invasive treatment for high-risk and intermediate-risk patients, surgical aortic valves replacement (SAVR) was still considered as the gold standard for low-risk patients. TAVR could potentially be applied to lower-risk younger patients if the indications can be safely expanded to the patients and transcatheter aortic valve (TAV) long-term durability can match with that of surgical bioprostheses. In contrast to surgical aortic valves (SAVs), there have been limited clinical data on the …

Predictive Modeling Of Hip Dislocation: Assessment Of Surgical And Patient Factors To Reduce The Occurrence Of Hip Instability And Adverse Clinical Outcomes, Daniel N. Huff

Electronic Theses and Dissertations

Instability and dislocation remain leading indications for revision of primary Total Hip Arthroplasty (THA). Many studies have addressed the links between implant design and propensity for dislocation, however a comprehensive review of the ability of modern THA constructs to protect against joint instability is needed.

Accordingly, the objective of this study is to provide objective data about THA risks to be considered in the treatment algorithm to protect against adverse joint loading conditions and joint instability. Adverse loading conditions were assessed in a population of activities of daily living using data from telemetric hip implant representation in an FE simulation …

Cementless Tibial Base Micromotion During Activities Of Daily Living, Hayden Wilson

Electronic Theses and Dissertations

Initial stability of cementless total knee replacement (TKR) components is directly related to long-term fixation and success, as excess motion hinders bony ingrowth. To assess implant stability, there is a need for more physiologically accurate loading conditions, incorporating forces and displacements in all 6 degrees-of-freedom found in the knee joint, as well as understanding the impact of femoral flexion on conformity of tibiofemoral articulation. Understanding how different activities of daily living generate tibial micromotion yields insight into surgical technique considerations, and rehabilitation strategies post-operatively. ASTM F3141-15, which specifies knee flexion, Internal-External moment, Medial-Lateral, Anterior-Posterior and Superior-Inferior forces during gait and …

Restoring Cholesterol Homeostasis In Familial Hypercholesterolemia Cell Line Model, Lubna Hindi

Electronic Theses and Dissertations

Familial hypercholesterolemia (FH) is an autosomal dominant disorder that results in elevated levels of low-density lipoprotein cholesterol (LDL-C). This increase in serum cholesterol level has been shown to result in premature coronary artery disease (CAD) with devastating symptoms from a young age. Today, the prevalence of heterozygous FH (HeFH) and homozygous FH (HoFH) is estimated to be 1 in 320 and 1 in 160,000 people, respectively. FH is referred to as an underdiagnosed disease due to the large number of mutations that continues to grow. These mutations often exist in one of or a combination of three genes: low-density lipoprotein …