Biomedical Engineering and Bioengineering Commons^™

Evaluation Of Tissue-Engineered Tendon Enthesis Polymer Constructs, Joshua A. Bundy Bs, Mary Beth Wade Phd, Hitomi Nakao Md, Phillip Mcclellan Phd, Qing Yu Phd, Robin Jacquet-Childs Ms, William J. Landis Phd

Williams Honors College, Honors Research Projects

Both scientists and clinicians have proposed tissue engineering as the future of medicine. The possibilities for tissue engineering, that is, fabrication of tissues and organs in the laboratory and their translation to patients, appear to be endless, and many believe that this new approach in medicine will result in abolishing many common ailments, injuries, and congenital defects. Injuries to a tendon enthesis, the normal tissue connection between tendon and bone, are of particular concern to clinicians because of their frequency and failure to repair as a result of surgery. While these injuries may not be life threatening, they can certainly …

A Nonrigid Registration Method For Correcting Brain Deformation Induced By Tumor Resection, Yixun Liu, Chengjun Yao, Fotis Drakopoulos, Jinsong Wu, Liangfu Zhou, Nikos Chrisochoides

Computer Science Faculty Publications

Purpose: This paper presents a nonrigid registration method to align preoperative MRI with intraoperative MRI to compensate for brain deformation during tumor resection. This method extends traditional point-based nonrigid registration in two aspects: (1) allow the input data to be incomplete and (2) simulate the underlying deformation with a heterogeneous biomechanical model.

Methods: The method formulates the registration as a three-variable (point correspondence, deformation field, and resection region) functional minimization problem, in which point correspondence is represented by a fuzzy assign matrix; Deformation field is represented by a piecewise linear function regularized by the strain energy of a heterogeneous biomechanical …

Interactions Of Peptide Triazole Thiols With Env Gp120 Induce Irreversible Breakdown And Inactivation Of Hiv-1 Virions, Arangassery Bastian, Mark Contarino, Lauren D. Bailey, Rachna Aneja, Diogo Rodrigo Magalhaes Moreira, Kevin Freedman, Karyn Mcfadden, Caitlin Duffy, Ali Emileh

Dartmouth Scholarship

Background: We examined the underlying mechanism of action of the peptide triazole thiol, KR13 that has been shown previously to specifically bind gp120, block cell receptor site interactions and potently inhibit HIV-1 infectivity.

Results: KR13, the sulfhydryl blocked KR13b and its parent non-sulfhydryl peptide triazole, HNG156, induced gp120 shedding but only KR13 induced p24 capsid protein release. The resulting virion post virolysis had an altered morphology, contained no gp120, but retained gp41 that bound to neutralizing gp41 antibodies. Remarkably, HIV-1 p24 release by KR13 was inhibited by enfuvirtide, which blocks formation of the gp41 6-helix bundle during membrane fusion, while …

Layered Long Term Co-Culture Of Hepatocytes And Endothelial Cells On A Transwell Membrane: Toward Engineering The Liver Sinusoid, Young Bok (Abraham) Kang, Siddhartha Rawat, Joseph Cirillo, Michael Bouchard, Hongseok (Moses) Noh

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

This paper presents a novel liver model that mimics the liver sinusoid where most liver activities occur. A key aspect of our current liver model is a layered co-culture of primary rat hepatocytes (PRHs) and primary rat liver sinusoidal endothelial cells (LSECs) or bovine aortic endothelial cells (BAECs) on a transwell membrane. When a layered co-culture was attempted with a thin matrigel layer placed between hepatocytes and endothelial cells to mimic the Space of Disse, the cells did not form completely separated monolayers. However, when hepatocytes and endothelial cells were cultured on the opposite sides of a transwell membrane, PRHs …

Electrotransfer Of Single-Stranded Or Double-Stranded Dna Induces Complete Regression Of Palpable B16.F10 Mouse Melanomas, Loree Heller, Vesba Todorovic, Maja Cemazar

Bioelectrics Publications

Enhanced tumor delivery of plasmid DNA with electric pulses in vivo has been confirmed in many preclinical models. Intratumor electrotransfer of plasmids encoding therapeutic molecules has reached Phase II clinical trials. In multiple preclinical studies, a reduction in tumor growth, increased survival or complete tumor regression have been observed in control groups in which vector or backbone plasmid DNA electrotransfer was performed. This study explores factors that could produce this antitumor effect. The specific electrotransfer pulse protocol employed significantly potentiated the regression. Tumor regression was observed after delivery of single-stranded or double-stranded DNA with or without CpG motifs in both …

Functional 3-D Cellulose & Nitrocellulose Paper-Based, Multiplex Diagnostic Platforms Without Coupling Agents, Mackenzie Elizabeth Tageson

Master's Theses

The purpose of this thesis was to demonstrate device functionality of 3-D paper-based, multiplex platforms, µPADs, without the use of coupling agents between layers. Previously, these platforms were fabricated with double-sided tape and cellulose powder to try to augment proper fluid routing, but difficulties with this method occurred. An acrylic housing unit with strategically placed pressure tabs was designed to aid horizontal and vertical fluid routing through the platform, thus eliminating the inconsistencies associated with coupling agents. Channel characterization studies, a COMSOL^TM simulation, and development time studies were performed to aid device design and demonstrate device functionality.

The implementation …

Formulation Development Of A Polymer-Drug Matrix With A Controlled Release Profile For The Treatment Of Glaucoma, Eric W. Tsoi

Master's Theses

Glaucoma is the leading cause of blindness in the United States accounting for 9-12% of all cases of blindness. Currently, the front line treatment for glaucoma are prostaglandins that may have to be taken up to several times a day. Even with proper treatment, roughly 11% of the patients using the treatment are non-compliant and lose their vision. In this project, ForSight Laboratories has developed a pharmaceutical drug delivering implant with the capability of sustaining long-term release of a prostaglandin as a new way to treat the condition. This project reports the product development of a polymer drug matrix with …

Dopaminergic Modulation Of Memory And Affective Processing In Parkinson Depression, Lee X. Blonder, John T. Slevin, Richard J. Kryscio, Catherine A. Martin, Anders H. Andersen, Charles D Smith, Frederick A. Schmitt

Magnetic Resonance Imaging and Spectroscopy Center Faculty Publications

Depression is common in Parkinson's disease and is associated with cognitive impairment. Dopaminergic medications are effective in treating the motor symptoms of Parkinson's disease; however, little is known regarding the effects of dopaminergic pharmacotherapy on cognitive function in depressed Parkinson patients. This study examines the neuropsychological effects of dopaminergic pharmacotherapy in Parkinsonian depression. We compared cognitive function in depressed and non-depressed Parkinson patients at two time-points: following overnight withdrawal and after the usual morning regimen of dopaminergic medications. A total of 28 non-demented, right-handed patients with mild to moderate idiopathic Parkinson's disease participated. Ten of these patients were depressed according …

Direct Quantitative Analysis Of Biomarkers Using Mass Spectrometry, Morgan N. Mcluckey, Zheng Ouyang

The Summer Undergraduate Research Fellowship (SURF) Symposium

Point-of-care (POC) diagnostics describes a step in the medical treatment process where drugs can be monitored in a patient’s body on-site and in a timely fashion. Mass spectrometry (MS) can provide a quick, efficient, and highly accurate method of analysis of patient biofluids and tissues. Developing methods to bring this diagnostic mechanism to hospitals and clinics has the potential to improve patient care through, for example, personalized medicine. Our goal was to develop a way to effectively introduce internal standard (IS), a necessary chemical for the analytical process, to low-volume biofluid samples. Additionally, the effective direct quantitation of biomarkers with …

Changes In Hemodynamic Responses In Chronic Stroke Survivors Do Not Affect Fmri Signal Detection In A Block Experimental Design, Nutta-On Promjunyakul, Brian D. Schmit, Sheila Schindler-Ivens

Physical Therapy Faculty Research and Publications

The use of canonical functions to model BOLD-fMRI data in people post-stroke may lead to inaccurate descriptions of task-related brain activity. The purpose of this study was to determine whether the spatiotemporal profile of hemodynamic responses (HDRs) obtained from stroke survivors during an event-related experiment could be used to develop individualized HDR functions that would enhance BOLD-fMRI signal detection in block experiments. Our long term goal was to use this information to develop individualized HDR functions for stroke survivors that could be used to analyze brain activity associated with locomotor-like movements. We also aimed to examine the reproducibility of HDRs …

Spectral Discrimination Of Breast Pathologies In Situ Using Spatial Frequency Domain Imaging, Ashley M. Laughney, Venkataramanan Krishnaswamy, Elizabeth J. Rizzo, Mary C. Schwab, Richard J. Barth, David J. Cuccia, Bruce J. Tromberg, Keith D. Paulsen, Brian W. Pogue, Wendy A. Wells

Dartmouth Scholarship

Introduction: Nationally, 25% to 50% of patients undergoing lumpectomy for local management of breast cancer require a secondary excision because of the persistence of residual tumor. Intraoperative assessment of specimen margins by frozen-section analysis is not widely adopted in breast-conserving surgery. Here, a new approach to wide-field optical imaging of breast pathology in situ was tested to determine whether the system could accurately discriminate cancer from benign tissues before routine pathological processing.

Interleukin Expression After Injury And The Effects Of Interleukin-1 Receptor Antagonist, Connie S. Chamberlain, Ellen M. Leiferman, Kayt E. Frisch, Stacey L. Brickson, William L. Murphy, Geoffrey S. Baer

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Ligament and tendon repair involves a complex series of coordinated events orchestrated by various cell types, cytokines and other factors. The repair process extends months to years and results in scar tissue mechanically inferior to native tissue. This is in clear contrast to tissue "regeneration" which would recapitulate the native tissue. Numerous approaches to stimulate a regenerative scenario have been attempted, including tissue-engineering, non-steroidal anti-inflammatories, ultrasonic, or electrical stimulation, but none have resulted in complete regeneration. In pursuit of a more regenerative outcome, it is important to understand the fundamentals of the normal healing process. Previous work from our lab …

Polysaccharide-Based Nanocarriers For Improved Drug Delivery, Nan Zhang

Dissertations - ALL

The field of drug delivery has provided a solution to the limited efficacy and high toxicity of many drugs. Nano-sized drug carriers are popular because their size allows for selective accumulation in the diseased area. Polysaccharides are non-toxic and biodegradable natural polymers that can serve as the basis for these nano-sized carriers. Polysialic acid (PSA) is such a polysaccharide with strong hydrophilicity that may reduce uptake by the reticuloendothelial system and prolong drug circulation. In this study, we developed PSA-based nanocarriers, specifically micelles and nanoparticles, for improved drug delivery with improved efficacy and minimized toxicity. PSA-based micelle systems were developed …

Hybrid Nanostructured Textile Bioelectrode For Unobtrusive Health Monitoring, Pratyush Rai

Graduate Theses and Dissertations

Coronary heart disease, cardiovascular diseases and strokes are the leading causes of mortality in United States of America. Timely point-of-care health diagnostics and therapeutics for person suffering from these diseases can save thousands of lives. However, lack of accessible minimally intrusive health monitoring systems makes timely diagnosis difficult and sometimes impossible. To remedy this problem, a textile based nano-bio-sensor was developed and evaluated in this research. The sensor was made of novel array of vertically standing nanostructures that are conductive nano-fibers projecting from a conductive fabric. These sensor electrodes were tested for the quality of electrical contact that they made …

Efferent Copy And Corollary Discharge Motor Control Behavior Associated With A Hopping Activity, Wangdo Kim, António P. Veloso, Filipa João, Sean S. Kohles

Mechanical and Materials Engineering Faculty Publications and Presentations

Hoppers respond not only to stimuli from the ground surfaces but also to cues generated by their own behaviors. This leads to desensitization because although the afferent and reafferent signals have distinct causes, they are carried by the same sensory channels. From a behavioral viewpoint, it may be necessary to distinguish between signals from the two causes especially when monitoring changes in the external environment separate from those due to self-movement. We were able to separate afferent sensory stimuli from self-generated, reafferent signals using an action oriented perception system and dynamic programming approach. This effort addressed the question of how …

Fluorescence Characterization Of Quantum Dots For Use As Biomarkers, Logan M. Grimes

Materials Engineering

Fluorescence profiles of quantum dots (QDs) were characterized to select the ideal QDs for encapsulation in phospholipids for use as biomarkers to selectively adhere to cancer cells. QDs were synthesized and extracted 0, 30, 60, and 90 seconds after precursor compounds were mixed. These extractions were isolated by extraction time. Portions from each vial were coated in a zinc sulfide shelling procedure, leaving at least half of the QD solution unshelled. These samples were characterized over four days to monitor fluctuations in fluorescence. This was done utilizing an Ocean Optics spectrometer in conjunction with Spectra Suite software. The central wavelength, …

Beach Wheelchair Project, Rory Aronson, Joshua Marcum, Samuel Coyne, Alex Hayes, Alexa Colburn, Max Hessel, Benedikt Strauss, Marvin Rimmele, Marco Pietsch

Mechanical Engineering

The Beach Wheelchair, Sandcrawler, is a machine intended to help give people with disabilities the full beach experience. The non-profit organization Bridge II Sports sponsored this project, and tasked us with developing the design and fabricating a prototype. This chair has several features including a linkage mechanism that raises and lowers a chair relative to an external frame, hand crank drive with Gates Carbondrive belt and sprockets, buoyant Wheeleez balloon tires, and much more.

Evaluation Of The Anterior Talofibular And Calcaneofibular Ligament In Relation To Supination Ankle Sprains, Peter Tran

Biomedical Engineering

Ankle injuries have always posed an issue to a number of athletes. Sports that involve running and jumping accumulate about 25% of injuries correlating to ankle sprains. In most ankle sprains the inversion (supination) of the ankle cause damage to lateral ligaments. The two most common lateral ligaments to experience damage are the anterior talofibular (ATFL) and calcaneofibular (CFL) ligaments. The methods of taping and ankle braces have allowed athletes to prevent recurring sprains from occurring. However, sprains can still occur even when one or both methods are applied. The purpose of each method is to restrict the range of …

Dynamic Dual-Tracer Mri-Guided Fluorescence Tomography To Quantify Receptor Density In Vivo, Scott C. Davis, Kimberley S. Samkoe, Kenneth M. Tichauer, Kristian J. Sexton, Jason R. Gunn, Sophie J. Deharvengt, Tayyaba Hasan, Brian W. Pogue

Dartmouth Scholarship

The up-regulation of cell surface receptors has become a central focus in personalized cancer treatment; however, because of the complex nature of contrast agent pharmacokinetics in tumor tissue, methods to quantify receptor binding in vivo remain elusive. Here, we present a dual-tracer optical technique for noninvasive estimation of specific receptor binding in cancer. A multispectral MRI-coupled fluorescence molecular tomography system was used to image the uptake kinetics of two fluorescent tracers injected simultaneously, one tracer targeted to the receptor of interest and the other tracer a nontargeted reference. These dynamic tracer data were then fit to a dual-tracer compartmental model …

Biomedical Photoacoustic Imaging Using Gas-Coupled Laser Acoustic Detection, Jami Johnson

Student Research Initiative

Several detection methods have been explored for photoacoustic and ultrasound imaging of biological tissues. Piezoelectric transducers are commonly used, which require contact with the sample to be imaged and have limiting bandwidth characteristics. Interferometry detection exhibits improved bandwidth characteristics and resolution, yet generally require complicated optics and the incorporation of a contacting reflective medium. In this paper, we report the use of a noncontact photoacoustic imaging system that does not require the use of a reflective layer. A simple, robust technique known as gas-coupled laser acoustic detection is used, which has previously been applied to evaluation of composite materials. This …

Delayed Thrombus Resolution And Fibroproliferative Vascular Wound Healing From Deficiency Of Type Iii Collagen: A Paradoxical Mechanism For Tissue Fragility, Amy J. Reid

Dissertations and Theses (Open Access)

Vascular Ehlers-Danlos syndrome is a heritable disease of connective tissue caused by mutations in COL3A1, conferring a tissue deficiency of type III collagen. Cutaneous wounds heal poorly in these patients, and they are susceptible to spontaneous and catastrophic rupture of expansible hollow organs like the gut, uterus, and medium-sized to large arteries, which leads to premature death. Although the predisposition for organ rupture is often attributed to inherent tissue fragility, investigation of arteries from a haploinsufficient Col3a1 mouse model (Col3a1^+/-) demonstrates that mutant arteries withstand even supraphysiologic pressures comparably to wild-type vessels. We hypothesize that injury …

Design And Testing Of Novel Mouthguard With Intermediate Nitinol And Foam Layers, Adam Kessler

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is the aim of this study to investigate a novel mouthguard design that incorporates the use of a nickel-titanium (Nitinol) layer and thin foam layer in addition to EVA layers. It is thought that the Nitinol layer can distribute the force of an impact and that the thin foam layer may absorb this distributed force better than a solid EVA mouthguard of the same thickness. Rectangular, flat coupons representative of several mouthguard configurations were constructed for testing using an instrumented drop-weight impact tower. The coupon configurations include a control made of laminated EVA, a group of laminated EVA and …

Closed Loop Control Of A Cylindrical Tube Type Ionic Polymer Metal Composite (Ipmc), Benjamin Mead

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal of this research is to provide a framework for the integration of tube type, cylindrical Ionic Polymer Metal-Composite (IPMC) into conventional devices. IPMCs are one of the most widely used types of electro-active polymer actuator, due to their low electric driving potential and large deformation range. For this research a tube type IPMC was investigated. This IPMC has a circular cross section with four separate electrodes on its surface and a hole through the middle. The four electrodes allow for biaxial bending and accurate control of the tip location. One of the main advantages of using this type …

Design And Implementation Of Wireless Point-Of-Care Health Monitoring Systems: Diagnosis For Sleep Disorders And Cardiovascular Diseases, Se Chang Oh

Graduate Theses and Dissertations

Chronic sleep disorders are present in 40 million people in the United States. More than 25 million people remain undiagnosed and untreated, which accounts for over $22 billion in unnecessary healthcare costs. In addition, another major chronic disease is the heart diseases which cause 23.8% of the deaths in the United States. Thus, there is a need for a low cost, reliable, and ubiquitous patient monitoring system. A remote point-of-care system can satisfy this need by providing real time monitoring of the patient's health condition at remote places. However, the currently available POC systems have some drawbacks; the fixed number …

Low Soluble Drug Encapsulation Based On Architecture Of Layer-By-Layer Assembly For Longer Circulation Time And Targeted Therapy, Pravin Pattekari

Doctoral Dissertations

A combined effect of sonication and layer-by-layer assembly (LbL) enhances the solubility of many poorly soluble inorganic and organic materials by forming stable particles with ca. 200 nm size and up to 90 wt% of loading. The entire method is reproducible, easy-to-handle, and flexible for varying surface properties according to the application of the materials. The method develops good colloidal stability of materials in buffers and maintains architecture for future improvement. A top-down approach, with a combined effect of sonication and LbL assembly, ruptures the material and allows adsorption of oppositely charged polyelectrolytes simultaneously. Thus, the approach is applicable for …

The Effect Of Network Transitions On Spontaneous Activity And Sycnhrony In Devloping Neural Networks, Jude P. J. Savarraj

Doctoral Dissertations

Connectivity patterns of developing neural circuits and the effects of its dynamics on network behavior, particularly the emergence of spontaneous activity and synchrony, are not clear. We attempt to quantify anatomical connectivity patterns of rat cortical cultures during different stages of development. By culturing the networks on dishes embedded with micro electrode arrays, we simultaneously record electrical activity from multiple regions of the developing network and monitor its electrical behavior, particularly its tendency to fire spontaneously and to synchronize under certain conditions. We investigate possible correlations between changes in the network connectivity patterns and spontaneous electrical activity and synchrony. Cocultures …

Tracking Knee Joint Functional Axes Through Tikhonov Filtering And Plűcker Coordinates, Wangdo Kim, Yoon-Hyuk Kim, António P. Veloso, Sean S. Kohles

Mechanical and Materials Engineering Faculty Publications and Presentations

Researchers have reported several compensation methods to estimate bone and joint position from a cluster of skin-mounted markers as influenced by Soft Tissue Artifacts (STA). Tikhonov Regularization Filtering (TRF) as a means to estimate Instantaneous Screw Axes (ISA) was introduced here as a means to reduce the displacement of a rigid body to its simplest geometric form. Recent studies have suggested that the ISA of the knee, i.e., Knee Functional Axes (KFA), might be closely connected to the estimation of constraint forces such as those due to medial and lateral connective tissues. The estimations of ISAs were known to be …

Scanning In Situ Spectroscopy Pplatform For Imaging Surgical Breast Tissue Specimens, Venkataramanan Krishnaswamy, Ashley M. Laughney, Wendy A. Wells, Keith D. Paulsen, Brian W. Pogue

Dartmouth Scholarship

A non-contact localized spectroscopic imaging platform has been developed and optimized to scan 1 x 1 cm² square regions of surgically resected breast tissue specimens with ~150-micron resolution. A color corrected, image-space telecentric scanning design maintained a consistent sampling geometry and uniform spot size across the entire imaging field. Theoretical modeling in ZEMAX allowed estimation of the spot size, which is equal at both the center and extreme positions of the field with ~5% variation across the designed waveband, indicating excellent color correction. The spot sizes at the center and an extreme field position were also measured experimentally using the …

Automated Point-Of-Care Image Processing Methodology For The Diagnosis Of Malaria, Michael B. Jorgensen

Master's Theses

Malaria has profoundly influenced human history for over four thousand years and despite numerous attempts at eradication, the prevention, diagnosis, and treatment of malaria have been largely ineffective. More than five hundred million people are affected by malaria every year resulting in over one million deaths. Drug resistance development by the parasite has diminished the effectiveness of numerous treatment options due, in part, to overtreatment of negative patients based on insufficient clinical algorithms and diagnostic methods. The goal of this research was to develop an image analysis algorithm to diagnose malaria with a high degree of sensitivity and specificity in …

A Hierarchical Method For Removal Of Baseline Drift From Biomedical Signals: Application In Ecg Analysis, Yurong Luo, Rosalyn H. Hargraves, Ashwin Belle, Ou Bai, Xuguang Qi, Kevin R. Ward, Michael Paul Pfaffenberger, Kayvan Najarian

Computer Science Publications

Noise can compromise the extraction of some fundamental and important features from biomedical signals and hence prohibit accurate analysis of these signals. Baseline wander in electrocardiogram (ECG) signals is one such example, which can be caused by factors such as respiration, variations in electrode impedance, and excessive body movements. Unless baseline wander is effectively removed, the accuracy of any feature extracted from the ECG, such as timing and duration of the ST-segment, is compromised. This paper approaches this filtering task from a novel standpoint by assuming that the ECG baseline wander comes from an independent and unknown source. The technique …