Biomedical Engineering and Bioengineering Commons^™

Peracetic Acid Sterilization Of Electrospun Polycaprolactone Scaffolds, Suyog Yoganarasimha

Theses and Dissertations

Sterilization of tissue engineered scaffolds is an important regulatory issue and is at the heart of patient safety. With the introduction of new biomaterials and micro/nano structured scaffolds, it is critical that the mode of sterilization preserve these built-in features. Conventional sterilization methods are not optimal for engineered polymeric systems and hence alternate systems need to be identified and validated. PCL is polyester with a low melting point (heat labile), susceptible to hydrolysis and is popular in tissue engineering. Electrospinning generates some nanoscale features within the scaffold, the integrity of which can be affected by sterilization method. Chapter 1 explores …

Engineering Of Polyamidoamine Dendrimers For Cancer Therapy, Leyuan Xu

Theses and Dissertations

Dendrimers are a class of polymers with a highly branched, three-dimensional architecture comprised of an initiator core, several interior layers of repeating units, and multiple active surface terminal groups. Dendrimers have been recognized as the most versatile compositionally and structurally controlled nanoscale building blocks for drug and gene delivery. Polyamidoamine (PAMAM) dendrimers have been most investigated because of their unique structures and properties. Polycationic PAMAM dendrimers form compacted polyplexes with nucleic acids at physiological pH, holding great potential for gene delivery.

Folate receptor (FRα) is expressed at very low levels in normal tissues but expressed at high levels in cancers …

Polysaccharide-Based Shear Thinning Hydrogels For Three-Dimensional Cell Culture, Vasudha Surampudi

Theses and Dissertations

The recreation of the complicated tissue microenvironment is essential to reduce the gap between in vitro and in vivo research. Polysaccharide-based hydrogels form excellent scaffolds to allow for three-dimensional cell culture owing to the favorable properties such as capability to absorb large amount of water when immersed in biological fluids, ability to form “smart hydrogels” by being shear-thinning and thixotropic, and eliciting minimum immunological response from the host. In this study, the biodegradable shear-thinning polysaccharide, gellan-gum based hydrogel was investigated for the conditions and concentrations in which it can be applied for the adhesion, propagation and assembly of different mammalian …

Neural Network Based Emg Driven Modeling And Control Of Human Walking, Alaa Muheddin Abdulrahman

Theses and Dissertations

Human body modeling (HBM) offers the benefit of replicating human activity into robotics and rehabilitation devices. Gait impairment is a consequence of several diseases like stroke, spinal cord injury, or Parkinson' disease. The modeling techniques developed in robotics have been used to improve gait abnormalities in walking and in building Exoskeletal robots. HBM is resource intensive as it requires setting-up laboratory facilities and using expensive instruments. Further, the data acquired is limited to the number of the participants. In addition, the accuracy of the model is important as it is related to human pathology. In this research, several Matlab based …

Experimental And Theoretical Studies Of Native And Engineered Vascular Tissue Mechanics, Boran Zhou

Theses and Dissertations

Background: Implantation of vascular grafts provides a means to restore blood flow in compromised regions of the circulatory system, and thus is used to treat a wide range of cardiovascular diseases. Despite significant advancements in autologous grafting strategies as well as the engineering of synthetic alternatives, mechanical, structural, and compositional incongruities between the graft and the host artery remain as contributing factors to graft failure. The typical failure modality manifests as proximal anastomotic intimal hyperplasia, which places restrictions on the host vessel size currently treated with grafting strategies (> 5 mm internal diameter). In order to improve long-term clinical outcomes, …

Effect Of Thermal Treatments On Mechanical Properties And Bioactivity Of Third Generation Of Bioactive Glass. A Step For Commercialization Success Of Third Generation Bioactive Glasses, Rajan Pandya

Theses and Dissertations

Unavailability of donors for transplanting bone to help people with orthopedic imparities gave rise to the metal implants that could be made in factories. This seemed like a good solution as it was available to all the people who needed it. It came with limitations such as restricted movement, infection, wear and tear of the surrounding tissue, and rejection. Biologically active implants were introduced by Dr. Larry Hench in 1960s [12]. The field of regenerative medicine has been changing rapidly since then. Biologically active implants facilitate bone regeneration and do not harm the surrounding tissue in any way. The bioactive …

Measurements Of Dna Damage And Repair In Bacillus Anthracis Sterne Spores By Uv Radiation, Chelsea C. Marcum

Theses and Dissertations

Spores of Bacillus anthracis (Ba) sterne were irradiated with 267nm UV light using small light emitting diodes. The pRB373 plasmid with a red fluorescent protein was transformed into Ba sterne cells prior to irradiation. Following irradiation, germination media was added and the spores were incubated for various times, to allow for DNA repair. The pRB373 plasmid was isolated and analyzed using real-time PCR. Primers were designed across the RFP in the plasmid yielding two amplicons, 245bp and 547bp long. PCR amplification was not achieved for germinated samples. Spore samples isolated using bead beating methods were amplified. Results indicate a quicker …

A Three-Dimensional In Vitromodel Of Atherogenesis, Pin Hsuan Chang

Theses and Dissertations

Atherosclerosis is the narrowing of arteries caused by accumulation of cholesterol, calcium and other cellular debris in the inner arterial wall. While extensive studies have been focusing on the inflammatory mechanisms of the disease, pathological and experimental evidence has shown that regions of disturbed flow are susceptible to the atherogenesis. To further understand the relationship between hemodynamics and atherogenesis, this research aims to generate a dynamic, 3D in vitro model of atherogenesis. This will allow for the investigation of specific cellular and molecular mechanisms of plaque formation that will pave the way for new therapies for the disease. A novel …

Developing A Bioreactor For Biaxial Mechanical Testing And Conditioning Of Vascular Tissue, Steve Marcous

Theses and Dissertations

Cardiovascular diseases are known to be one of the major causes of death around the world. One of the major causes of cardiovascular disease is arterial malfunction. Arteries malfunction when they experience chronic perturbations in their local environment above normal levels. Hence, we developed a bioreactor system in order to study the effect of chronic changes in the arterial global parameters (axial force, luminal pressure, and flow rate) on the behavior of local parameters (circumferential stress, axial stress, and flow induced shear stress). The bioreactor system was designed to (i) perform biaxial mechanical testing, (ii) incorporate, for the first time, …

Analyzing Thermal And Mechanical Effects Of Pulsed Laser Irradiation On Tissues, Mohit Ganguly

Theses and Dissertations

Pulsed lasers are known for their spatial and temporal specificity in delivering heat energy to the tissues. This is useful in laser ablation treatment mechanism where damage to the healthy tissues is highly undesired. However, the efficacy of the process is limited by the damage caused by the pulsed laser. A pulsed laser has both photothermal and photomechanical interaction with tissues. Photothermal interaction is caused by the rise in temperature due to the laser irradiation. This includes the denaturation of proteins, increased mitochondrial membrane permeability and ultimately vaporization. Photomechanical interaction causes the generation of pressure waves produced as a result …

Synthesis And Characterization Of Clickable Dendrimer Hydrogels For Ocular Drug Delivery, Jingfei Tian

Theses and Dissertations

Topical medication is a standard treatment for glaucoma. However, frequent dosing makes the therapy inconvenient and patient unfriendly. There is a great need to develop new topical formulations that provide long lasting noninvasive drug release. In this thesis, novel clickable dendrimer hydrogels for anti-glaucoma drug delivery were synthesized and characterized. Polyamidoamine (PAMAM) dendrimers have been widely applied for drug delivery. The physical characteristics they possess include monodispersity, water solubility, encapsulation ability, and a large number of surface groups. Polycationic PAMAM dendrimer G3 was surface modified with alkyne-PEG5-acid and then reacted with polyethylene glycol bisazide (PEG-BA, 1100 gmol-1) through click chemistry …

Mammary Epithelial Cells Cultured Onto Non-Woven Nanofiber Electrospun Silk-Based Biomaterials To Engineer Breast Tissue Models, Yas Maghdouri-White

Theses and Dissertations

Breast cancer is one of the most common types of cancer affecting women in the world today. To better understand breast cancer initiation and progression modeling biological tissue under physiological conditions is essential. Indeed, breast cancer involves complex interactions between mammary epithelial cells and the stroma, both extracellular matrix (ECM) and cells including adipocytes (fat tissue) and fibroblasts (connective tissue). Therefore, the engineering of in vitro three-dimensional (3D) systems of breast tissues allows a deeper understanding of the complex cell-cell and cell-ECM interactions involved during breast tissue development and cancer initiation and progression. Furthermore, such 3D systems may provide a …

Feature Selection On Hyperspectral Data For Dismount Skin Analysis, Lindsay R. Cain

Theses and Dissertations

Many security applications require the ability to accurately identify dismounts based on their distinctive identification properties. A dismount can be identified by many personal characteristics to include clothing, height, and gait. In particular, a dismount's skin can be used as an identifying feature because of the vast variability of skin pigmentation amongst individuals. Hyperspectral data, which is comprised of hundreds of spectral channels sampled from a nearly contiguous electromagnetic spectrum, is used to detect skin spectral variability amongst dismounts. However, hyperspectral data is often highly correlated and computationally expensive to process. Feature selection methods can be employed to reduce the …

An Analysis Of Eye Movements With Helmet Mounted Displays, Kalyn A. Tung

Theses and Dissertations

Helmet or Head-Mounted Displays (HMD) applications have expanded to include a range from advanced military cockpits to consumer glasses. However, users have documented loss of legibility while undergoing vibration. Recent research indicates that undesirable eye movement is related to the vibration frequency a user experiences. In vibrating environments, two competing eye reflexes likely contribute to eye movements. The Vestibulo-ocular Reflex responds to motion sensed in the otoliths while the pursuit reflex is driven by the visual system to maintain the desired image on the fovea. This study attempts to isolate undesirable eye motions that occur while using a HMD by …

Novel Technologies For The Detection And Mitigation Of Drowsy Driving, Samuel Lawoyin

Theses and Dissertations

In the human control of motor vehicles, there are situations regularly encountered wherein the vehicle operator becomes drowsy and fatigued due to the influence of long work days, long driving hours, or low amounts of sleep. Although various methods are currently proposed to detect drowsiness in the operator, they are either obtrusive, expensive, or otherwise impractical. The method of drowsy driving detection through the collection of Steering Wheel Movement (SWM) signals has become an important measure as it lends itself to accurate, effective, and cost-effective drowsiness detection. In this dissertation, novel technologies for drowsiness detection using Inertial Measurement Units (IMUs) …

Identifying Performance Criteria Of Fully Bioresorbable Scaffolds For Endovascular Applications, Jahid Ferdous

Theses and Dissertations

Background: Bioresorbable scaffolds (BRS) have revolutionized percutaneous coronary intervention in clinical cardiovascular medicine. As opposed to permanent alternatives such as metallic stents, BRS have an inherent potential to reduce the occurrence of untoward events such as vessel re-narrowing or thrombosis by virtue of undergoing complete and controlled resorption post- implantation. While BRS platforms demonstrate a clear potential to mitigate risk stemming from incomplete vessel healing, they introduce a new set of considerations to clinical safety and efficacy. Foremost among these issues is the fate of and biological response to material by-products that evolve throughout the scaffold degradation and erosion processes, …

Isolation Of Natural Nrf2 Activators From American Ginseng, Akrm Abdalrahman

Theses and Dissertations

Nuclear factor erythroid-2 related factor 2 (Nrf2), a major transcription factor of the endogenous antioxidant defense system, has been proposed as a potential therapeutic target for the treatment of various diseases. However, a small molecule-driven Nrf2 signaling therapeutic approach remains to be established. Herein, we report one such possibility discovered by the bioassay-based fractionation of American ginseng. Since crude extract of American ginseng was found to suppress the expression of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-inflamed macrophages via activating Nrf2, we further fractioned the crude extract using solvents including hexane, dichloromethane, ethyl acetate, butanol, and water, and found …

Discovery And Characterization Of Multi-Target Directed Ligands As Inhibitors Of Amyloid-Β Aggregation And Regulators Of Alzheimer's Disease, Jui-Heng Tseng

Theses and Dissertations

Alzheimer's disease (AD) is the most common neurodegenerative disease in the world. As the disease advances, symptoms include confusion, language skill breakdown, and long term memory loss - and culminate in death. Existing therapies for AD provide symptomatic benefits but cannot halt or slow the disease pathogenesis.

Increasing evidence reveals the multi-factorial nature of AD. Numerous factors, including amyloid-β (Aβ) aggregation, calcium homeostasis dysregulation, and oxidative stress, contribute to disease development and interplay with each other. Therefore, multi-target directed ligands (MTDLs) may present an effective AD treatment. Among all factors, Aβ aggregation is suggested to play the most crucial role. …

Tissue Engineering Scaffold Fabrication And Processing Techniques To Improve Cellular Infiltration, Casey Grey

Theses and Dissertations

Electrospinning is a technique used to generate scaffolds composed of nano- to micron-sized fibers for use in tissue engineering. This technology possesses several key weaknesses that prevent it from adoption into the clinical treatment regime. One major weakness is the lack of porosity exhibited in most electrospun scaffolds, preventing cellular infiltration and thus hosts tissue integration. Another weakness seen in the field is the inability to physically cut electrospun scaffolds in the frontal plane for subsequent microscopic analysis (current electrospun scaffold analysis is limited to sectioning in the cross-sectional plane). Given this it becomes extremely difficult to associate spatial scaffold …

Android-Based Smartphone Application Simulation And Systematic Design To Reduce Medication Administration Error In Prehospital Emergency Care., Natalie Vazquez

Theses and Dissertations

Since 1999 when the report To Err is Human: Building a Safer Health System was released, medical errors have come into focus (Kohn, 2000). In an effort to reduce medication administration errors in prehospital emergency care, an android-based smartphone application simulation was created. The app has components including QR barcode scanning, text to speech for medication cross-checking, weight-based medication dose calculations, and time stamped medication data wirelessly transferring to a database in real-time. Color standard identification was implemented, aiding to a designed systematic process for patient treatment to reduce medication errors. Direct observation was performed of emergency patient calls with …

The Effect Of Simultaneous, Irrelevant Auditory And Visual Stimuli On A Forced-Attention Dichotic Listening Test, Keri Davis

Theses and Dissertations

Many of the studies examining cognitive control during selective attention across different sensory modalities conflict. This study was designed to study the effect of an irrelevant visual stimulus and an auditory distraction of backward speech on a forced attention dichotic listening test. I predicted that the visual stimulus and backward speech would not have a significant effect on the ear advantage. The results showed that all subjects were able to force their attention to the ear regardless of the visual or auditory distracters. In addition, I found that an irrelevant visual stimulus affects auditory attention more so in the left …

Novel 3d Head And Neck Cancer Model To Evaluate Chemotherapeutic Efficacy, Kelly Morgan

Theses and Dissertations

HNSCC accounts for 7 percent of all new cancer occurrences. Despite currently available treatments, there continues to be a high mortality and recurrence rate in HNSCC. Well over 50 percent of all cancer patients receive chemotherapy as a standard treatment. However, only 5 percent of these cases have been shown to help with treatment of the disease. Formerly, two options were available for drug testing: in vivo animal models, and in vitro two-dimensional models. While in vivo models remain the most representative, their use is burdened by high costs, time constraints, and ethical concerns. 2D models are simple to use …

Development Of A Compact, Low-Cost Wireless Device For Biopotential Acquisition, Graham Kelly

Theses and Dissertations

A low-cost circuit board design is presented, which in one embodiment is smaller than a credit card, for biopotential (EMG, ECG, or EEG) data acquisition, with a focus on EEG for brain-computer interface applications. The device combines signal conditioning, low-noise and high-resolution analog-to-digital conversion of biopotentials, user motion detection via accelerometer and gyroscope, user-programmable digital pre-processing, and data transmission via Bluetooth communications. The full development of the device to date is presented, spanning three embodiments. The device is presented both as a functional data acquisition system and as a template for further development based on its publicly-available schematics and computer-aided …

Analysis And Modeling Of The Roles Of Actin-Myosin Interactions In Bladder Smooth Muscle Biomechanics, Seyed Omid Komariza

Theses and Dissertations

Muscle mechanical behavior potentially plays an important role in some of the most common bladder disorders. These include overactive bladder, which can involve involuntary contractions during bladder filling, and impaired contractility or underactive bladder, which may involve weak or incomplete contractions during voiding. Actin-myosin cross-bridges in detrusor smooth muscle (DSM) are responsible for contracting and emptying the bladder. The total tension produced by muscle is the sum of its preload and active tensions. Studies suggest that actin-myosin cross-links are involved in adjustable preload stiffness (APS), which is characterized by a preload tension curve that can be shifted along the length …

Novel Conditioning Protocols Focusing On Oxygen Manipulation To Enhance Stem Cell Transplantation, Brandon William Hanna

Theses and Dissertations

Musculoskeletal tissue engineering involves the creation of multiple tissue types that interact together to form a particular function related to motion and maintaining the body's frame. In order to create a fully functional musculoskeletal system, a concrete method for the creation of the different tissue types must first be completed. Of the different tissue components related to the function of a musculoskeletal system, these studies deal with preconditioning circumstances of stem cells that will differentiate into cartilage and bone. These studies also deal with methods for the creation of functional bone and cartilage to be combined for the creation of …

Design And Validation Of A Computational Model For Study Of Scapholunate Joint Kinematics, Edward J. Tremols

Theses and Dissertations

As computational power has increased, computational modeling has become a very promising tool to model the biomechanics of complex joint systems. Musculoskeletal computational models have become more complex when compared to original iterations which utilized a number of simplifications. This thesis utilized a three-dimensional computational model of the wrist joint structure to investigate scapholunate kinematics. The model accurately represented the bony anatomy of the wrist and hand and represented soft tissue structures such as ligaments, tendons, and other surrounding tissues. Creation of the model was done using commercially available computer-aided design and medical image processing software, and utilized the rigid …

The Design And Validation Of A Computational Rigid Body Model For Study Of The Radial Head, Cassandra Woodcock

Theses and Dissertations

Rigid body modeling has historically been used to study various features of the elbow joint including both physical and computational models. Computational modeling provides an inexpensive, easily customizable, and effective method by which to predict and investigate the response of a physiological system to in vivo stresses and applied perturbations. Utilizing computer topography scans of a cadaveric elbow, a virtual representation of the joint was created using the commercially available MIMICS(TM) and SolidWorks(TM) software packages. Accurate 3D articular surfaces, ligamentous constraints, and joint contact parameters dictated motion. The model was validated against two cadaveric studies performed by Chanlalit et al. …

Localization Of Auditory Spatial Targets In Sighted And Blind Subjects, Richard Nuckols

Theses and Dissertations

This research was designed to investigate the fundamental nature in which blind people utilize audible cues to attend to their surroundings. Knowledge on how blind people respond to external spatial stimuli is expected to assist in development of better tools for helping people with visual disabilities navigate their environment. There was also interest in determining how blind people compare to sighted people in auditory localization tasks. The ability of sighted individuals, blindfolded individuals, and blind individuals in localizing spatial auditory targets was assessed. An acoustic display board allowed the researcher to provide multiple sound presentations to the subjects. The subjects’ …

Examination Of The Effect Of Different Training Metrics On Performance Of A Minimally Invasive Surgery Transfer Task, Cristofer Madera

Theses and Dissertations

The purpose of this experiment was to determine if there existed techniques to more efficiently train prospective surgeons the skills necessary to capably perform minimally invasive surgical procedures. Also, we wanted to know if trainees could be pushed to cognitively define a laparoscopic environment with a novel hand-eye relationship. To explore these questions, a simulation was setup wherein subjects would perform a laparoscopic transfer task and receive active feedback during training. Different subjects would receive different metrics as feedback and a comparison would be made between subjects with respect to standard metrics. Results of this experiment show that all subjects …

Patient-Specific Modeling Of Adult Acquired Flatfoot Deformity Before And After Surgery, Edward Meade Spratley

Theses and Dissertations

The use of computational modeling is an increasingly commonplace technique for the investigation of biomechanics in intact and pathological musculoskeletal systems. Moreover, given the robust and repeatable nature of computer simulation and the prevalence of software techniques for accurate 3-D reconstructions of tissues, the predictive power of these models has increased dramatically. However, there are no patient-specific kinematic models whose function is dictated solely by physiologic soft-tissue constraints, articular shape and contact, and without idealized joint approximations. Moreover, very few models have attempted to predict surgical effects combined with postoperative validation of those predictions. Given this, it is not surprising …