Biomechanics and Biotransport Commons^™

The Role Of Mechanical Loading In Chondrocyte Signaling Pathways, Qiaoqiao Wan

Open Access Dissertations

Chondrocytes are a predominant cell type present in articular cartilage, whose integrity is jeopardized in joint degenerative diseases such as osteoarthritis (OA). In the chondrocytes of patients with OA, the elevated levels of inflammatory cytokines such as interleukin 1β (IL1β) and tumor necrosis factor α (TNFα) have been reported. These cytokines contribute to degradation of cartilage matrix by increasing activities of proteolytic enzymes. In addition to their contribution to proteolytic enzymes, these cytokines adversely affect anabolic activity of chondrocytes by inhibiting the production of proteoglycans and type II collagen. Therefore, blocking the action of these cytokines is a potential strategy …

Fluid Flow Characterization And In Silico Validation In A Rapid Prototyped Aortic Arch Model, Alexandra Mariel Knauer

Master's Theses

Transcatheter aortic heart valve replacement (TAVR) is a procedure to replace a failing aortic valve and is becoming the new standard of care for patients that are not candidates for open-heart surgery [2]. However, this minimally invasive technique has shown to cause ischemic brain lesions, or “silent infarcts”, in 90% of TAVR patients, which can increase the patient’s risk for stroke by two to four times in future years [3]. Claret Medical Inc., a medical device company, has developed a cerebral protection system that filters and captures embolic debris released during endovascular procedures, such as TAVR. This thesis utilized CT …

Functional Comparison Of Conventional Afos With The Dynamic Response Afo, Mitchell Ruble

Master's Theses (2009 -)

Ankle foot orthoses (AFOs) are commonly prescribed to provide stability and foot clearance for patients with weakened or injured musculature. The Dynamic Response AFO (DRAFO) was designed to improve proprioception at heel strike. The design includes a rigid outer shell with a cut out heel and a soft inner lining; it is typically aligned in plantarflexion and may incorporate external heel wedges. The objective of this study was to investigate the effects of the DRAFO design features and contrast its biomechanical function with that of conventional locked and articulating AFOs. The research hypotheses were: 1) DRAFO-assisted gait parameters (e.g. ankle …

Microbubble Generation By Piezoelectric Transducers For Biomedical Studies, Mohammed Alkhazal

Electrical & Computer Engineering Theses & Dissertations

Bubbles induced by blast waves or shocks are speculated as the major cause of damage in biological cells in mild traumatic brain injuries (TBI). Microbubble collapse was found to induce noticeable cell detachment from the cell substrate, changes in focal adhesion, and biomechanics. To better understand the bubble mechanism, a system needs to be constructed which allows clear differentiation on the impact of bubbles from that of shocks. Such a generator needs to be low profile in order to place under a microscope. A piezoelectric transducer system was designed to meet the need. The system uses either a flat or …

Prosthetic Leg Kit For Deployment In Developing Countries, Brian Murphy, Dominique Porcincula, Derek Morgan, Kendall Ruggles, Christian Aguayo

Biomedical Engineering

The World Health Organization estimates that over 30 million people require some sort of prosthetic technology. However, traditional prosthetic fitting practices take a lot of time and cost a lot of money, making them inaccessible to millions of people around the world. StandUP Worldwide is an interdisciplinary project team devoted to creating low-cost prosthetic technologies for use around the world, especially in resource poor areas. They are currently developing a low cost, below-the-knee prosthetic kit that can be easily deployed in a resource-poor area. The following presents their solution for a below-the-knee prosthetic socket, foot, and leg.

The Effects Of Obesity On Resultant Knee Joint Loads For Gait And Cycling, Juan Gutierrez-Franco

Master's Theses

Osteoarthritis (OA) is a degenerative disease of cartilage and bone tissue and the most common form of arthritis, accounting for US$ 10.5 billion in hospital charges in 2006. Obesity (OB) has been linked to increased risk of developing knee OA due to increased knee joint loads and varus-valgus misalignment. Walking is recommended as a weight-loss activity but it may increase risk of knee OA as OB gait increases knee loads. Cycling has been proposed as an alternative weight-loss measure, however, lack of studies comparing normal weight (NW) and OB subjects in cycling and gait hinder identification of exercises that may …

The Role Of Intrinsic Foot Muscles In Three Running Footwear Conditions, Brian T. Groener

Senior Honors Projects, 2010-2019

Running has grown tremendously in popularity and so has running with minimalist shoes. Injuries such as plantar fasciitis (pain and inflammation of a thick band of tissue that runs across the bottom of the foot) are prevalent in runners despite efforts to design footwear to alleviate the impact of running and to reduce the number of injuries. In the past decade, minimalist running shoes have received considerable attention, causing debate amongst runners and scientists as to their utility in injury prevention. While running barefoot or in minimalist shoes reduces initial impact forces, the claim that they lower injury rates remains …

Localized Immunotherapy Delivery Using Injectable In Situ Forming Chitosan Hydrogel, Seth Washispack

Biomedical Engineering Undergraduate Honors Theses

Cytokine-based cancer immunotherapies stimulate a host’s immune system to fight cancer. In particular, interleukin-12 (IL-12), a potent pro-inflammatory cytokine, has demonstrated the ability to eliminate tumors in a number of preclinical models. Toxicities associated with the systemic delivery of IL-12 have precluded its use in the clinic. We are developing a novel chitosan-based hydrogel to maintain high local concentrations of cytokines, such as IL-12, in the tumor while minimizing its systemic dissemination. This hydrogel was found to form spontaneously within ten seconds of mixing two proprietary components. To increase the usefulness of the hydrogel, an efficient mixing and delivery system …

Development And Analysis Of A Statics And Kinematics Demonstration As A Learning Tool In The Biomechanics Classroom, Bethany D. Knight

Biomedical Engineering Undergraduate Honors Theses

This study was done with the objective of determining if students in the biomedical engineering department at the University of Arkansas would gain better understanding of basic biomechanics principles through the implementation of in-class demonstrations. Biomechanics was chosen because it is the first class taken in sequence after the “Introduction to Biomedical Engineering” class. A pre-demonstration survey was administered to gauge how comfortable the students were with the topics on the syllabus. Two demonstrations were done in class and related homework was assigned. The post-semester survey was administered and collected to determine how effective the students felt the presentations to …

Design Of Exercise Equipment For Wheelchair Users: A Case Study In Accessibility Standards, Kate Craddock Rescsanszky

Honors Scholar Theses

Engineers must consider a number of aspects of every project they work on. Accessibility is one aspect that presents a unique challenge. Rather than being based on absolute material parameters, accessibility is based on how people interact with technology and their built environment. Since 1990, the Americans with Disabilities Act has been the predominant standard in accessibility because of its wide reach and legal mandate. In addition to the ADA, the ASTM and the Institute for Universal Design offer helpful guidelines for designing for accessibility. However, in addition to standards, guidelines, and recommendations, it is important to consult the intended …

Hyaluronic Acid-Conjugated Liposome Nanoparticles For Targeted Delivery To Cd44 Overexpressing Glioblastoma Cells, Stephen L. Hayward, Christina L. Wilson, Srivatsan Kidambi

Department of Chemical and Biomolecular Engineering: Faculty Publications

Glioblastoma Multiforme (GBM) is a highly prevalent and deadly brain malignancy characterized by poor prognosis and restricted disease management potential. Despite the success of nanocarrier systems to improve drug/gene therapy for cancer, active targeting specificity remains a major hurdle for GBM. Additionally, since the brain is a multi-cell type organ, there is a critical need to develop an approach to distinguish between GBM cells and healthy brain cells for safe and successful treatment. In this report, we have incorporated hyaluronic acid (HA) as an active targeting ligand for GBM. To do so, we employed HA conjugated liposomes (HALNPs) to study …

A Principal Component Analysis Investigation Of Drop Landings For Defining Anterior Cruciate Ligament Injury Risk Factors, Emily Schaefer

Master's Theses (2009 -)

Injury to the anterior cruciate ligament (ACL) has been widely investigated through observational video analysis and laboratory based cadaveric, motion capture and computer simulation models. With the greater incidence of injury in the female population, recent emphasis has been placed on understanding ACL injury mechanisms in females. By using our understanding of injury mechanisms and prospective studies, injury prediction methods can be created. Once injury can be reliably predicted, training methods can be implemented to reduce likelihood of injury and avoid devastating consequences. There is a need for a reliable way to reduce motion capture data obtained in a laboratory …

Fluid Flow Characterization In Rapid Prototyped Common Iliac Artery Aneurysm Molds, Daniel Cole Greinke

Master's Theses

The goal of this project was to determine whether i) fused deposition modeling could be employed to manufacture molds for vascular constructs, ii) whether vascular constructs could be created from these molds, and iii) to verify practical equivalence between observed fluid velocities. Dye tracking was to be employed to characterize fluid velocity profiles through the in vitro vascular constructs, including a half-vessel model and a full vessel model of an iliac artery aneurysm. A PDMS half-vessel construct was manufactured, and the movement of dye through the construct was tracked by a cellphone camera. Thresholds were applied to each video in …

Expanded 3d Nanofiber Scaffolds: Cell Penetration, Neovascularization, And Host Response, Jiang Jiang, Zhuoran Li, Hongjun Wang, Yue Wang, Mark A. Carlson, Matthew J. Teusink, Matthew R. Macewan, Linxia Gu, Jingwei Xie

Department of Mechanical and Materials Engineering: Faculty Publications

Herein, a robust method to fabricate expanded nanofiber scaffolds with controlled size and thickness using a customized mold during the modified gas-foaming process is reported. The expansion of nanofiber membranes is also simulated using a computational fluid model. Expanded nanofiber scaffolds implanted subcutaneously in rats show cellular infiltration, whereas non-expanded scaffolds only have surface cellular attachment. Compared to unexpanded nanofiber scaffolds, more CD68+ and CD163+ cells are observed within expanded scaffolds at all tested time points post-implantation. More CCR7+ cells appear within expanded scaffolds at week 8 post-implantation. In addition, new blood vessels are present within the expanded scaffolds at …

Protein-Targeted Corona Phase Molecular Recognition, Gili Bisker, Juyao Dong, Hoyoung D. Park, Nicole M. Iverson, Jiyoung Ahn, Justin T. Nelson, Markita P. Landry, Sebastian Kruss, Michael S. Strano

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Corona phase molecular recognition (CoPhMoRe) uses a heteropolymer adsorbed onto and templated by a nanoparticle surface to recognize a specific target analyte. This method has not yet been extended to macromolecular analytes, including proteins. Herein we develop a variant of a CoPhMoRe screening procedure of single-walled carbon nanotubes (SWCNT) and use it against a panel of human blood proteins, revealing a specific corona phase that recognizes fibrinogen with high selectivity. In response to fibrinogen binding, SWCNT fluorescence decreases by >80% at saturation. Sequential binding of the three fibrinogen nodules is suggested by selective fluorescence quenching by isolated sub-domains and validated …

Three-Dimensional Endothelial Spheroid-Based Investigation Of Pressure-Sensitive Sprout Formation, Min Song

Theses and Dissertations--Biomedical Engineering

This study explored hydrostatic pressure as a mechanobiological parameter to control in vitro endothelial cell tubulogenesis in 3-D hydrogels as a model microvascular tissue engineering approach. For this purpose, the present investigation used an endothelial spheroid model, which we believe is an adaptable microvascularization strategy for many tissue engineering construct designs. We also aimed to identify the operating magnitudes and exposure times for hydrostatic pressure-sensitive sprout formation as well as verify the involvement of VEGFR-3 signaling. For this purpose, we used a custom-designed pressure system and a 3-D endothelial cell spheroid model of sprouting tubulogenesis. We report that an exposure …

The Rheological Impact Of Cell Activation On The Flow Behavior Of Neutrophils, Nolan M. Horrall

Theses and Dissertations--Biomedical Engineering

Previously, it was reported that the morphological changes (pseudopod projection) that circulating neutrophils adopt due to cell activation raises peripheral vascular resistance by disrupting microvascular rheology. Studies utilized murine muscle preparations to link neutrophil pseudopod formation to cell activation and a viscous impact on hemodynamic resistance. But because of the complexity associated with the organization of the vasculature and microvasculature in tissues, it was unclear whether the effects of neutrophil activation on hemodynamic resistance were associated with the macro-/micro- circulation. This research describes an in vitro analysis using viscometry and microvascular network mimics (microporous membranes) to assess the rheological impact …

Improved Capability Of A Computational Foot/Ankle Model Using Artificial Neural Networks, Ruchi D. Chande

Theses and Dissertations

Computational joint models provide insight into the biomechanical function of human joints. Through both deformable and rigid body modeling, the structure-function relationship governing joint behavior is better understood, and subsequently, knowledge regarding normal, diseased, and/or injured function is garnered. Given the utility of these computational models, it is imperative to supply them with appropriate inputs such that model function is representative of true joint function. In these models, Magnetic Resonance Imaging (MRI) or Computerized Tomography (CT) scans and literature inform the bony anatomy and mechanical properties of muscle and ligamentous tissues, respectively. In the case of the latter, literature reports …

Retargeting The Clostridium Botulinum C2 Toxin To The Neuronal Cytosol, Benjamin J. Pavlik, Elizabeth J. Hruska, Kevin E. Van Cott, Paul H. Blum

Department of Chemical and Biomolecular Engineering: Faculty Publications

Many biological toxins are known to attack specific cell types, delivering their enzymatic payloads to the cytosol. This process can be manipulated by molecular engineering of chimeric toxins. Using toxins with naturally unlinked components as a starting point is advantageous because it allows for the development of payloads separately from the binding/translocation components. Here the Clostridium botulinum C2 binding/translocation domain was retargeted to neural cell populations by deleting its non-specific binding domain and replacing it with a C. botulinum neurotoxin binding domain. This fusion protein was used to deliver fluorescently labeled payloads to Neuro-2a cells. Intracellular delivery was quantified by …

Reference Point Indentation Of Human Trabecular Bone Treated With Bisphosphonates For Varying Durations, Drew Jones

Theses and Dissertations--Biomedical Engineering

Reference point indentation (RPI), a novel form of micro-indentation, quantifies RPI material parameters which correlate with modulus, yield stress, strength, or toughness. Information linking bisphosphonate treatment length with the material properties of osteoporotic trabecular bone is needed to improve patient treatment. The objectives of this study were to: 1) determine if RPI can be used to successfully evaluate human trabecular bone and if so, determine an optimized test method for using RPI on trabecular bone, and 2) use this method to determine if any RPI parameters are related to the duration of bisphosphonate treatment.

Indentation using a 4 N applied …