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Theses/Dissertations

2011

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Full-Text Articles in Biomedical Engineering and Bioengineering

Cerebral Spasticity Modeled As Disorded Equilibrium Point Control, Darnell Simon Dec 2011

Cerebral Spasticity Modeled As Disorded Equilibrium Point Control, Darnell Simon

Dissertations

Spasticity is a highly complex phenomenon, which has not been defined in precise and quantifiable terms. Although the muscle stretch reflex is thought to play an important role in spasticity generation, the pathophysiologic basis of spasticity is not completely understood. A valid measure of spasticity is one that is chosen within the context of a theory describing the physiological mechanisms underlying the control of posture and movement in healthy individuals and possible impairments of these mechanisms leading to motor disorders. This research’s goal was to determine the role of stretch reflex threshold in the regulation of impaired motor control ...


Neural Differentiation Of Pluripotent Stem Cells And Applications To Micropatterned Agarose Hydrogel For Nerve Guidance, Jamila S. Gittens Dec 2011

Neural Differentiation Of Pluripotent Stem Cells And Applications To Micropatterned Agarose Hydrogel For Nerve Guidance, Jamila S. Gittens

Theses

Many central nervous system (CNS) disorders are attributable to damaged oligodendrocytes, the cells that form the myelin sheath of axons. An effective source of human oligodendrocytes is crucial, making pluripotent stem cells, such as embryonic stem (ES) cells, an attractive source for nerve tissue repair and regeneration due to their unlimited capacity for self-renewal and their ability to differentiate into all major cell lineages. Bioengineered 3-D hydrogel culture systems have the potential to elucidate mechanisms required for regeneration of CNS cells. The goals of this study are: (1) to investigate the effects of retinoic acid (RA), sonic hedgehog (shh) agonist ...


Temperature Elevations Due To Nir Exposure In The Brain Tissue, Ali Ersen Dec 2011

Temperature Elevations Due To Nir Exposure In The Brain Tissue, Ali Ersen

Theses

Near infrared (NIR) lasers have been used in medical applications both for diagnostic and therapeutic purposes. Temperature elevation profile inside the tissue is a critical factor that needs to be better understood in these applications. The purpose of this study is to determine the temperature distribution due to a low power N I R laser irradiation in living neural tissue. Temperature measurements were made directly using a thermocouple probe inside the rat brain cortex within the sagittal plane. The spatial map indicates that N I R light penetrates more readily in the vertical directions than the spreading in the horizontal ...


Soy Protein-Poly (L-Lactic Acid) Blend Nanofibers For Drug Delivery Of Nardostachys Jatamansi, Swetha Tiwari Dec 2011

Soy Protein-Poly (L-Lactic Acid) Blend Nanofibers For Drug Delivery Of Nardostachys Jatamansi, Swetha Tiwari

Theses

Electrospun nanofibers when nanofi bers are impregnated with drugs play a significant role in drug delivery. Nanomedical approaches to drug delivery focus on developing nanoscale particles or molecules to improve the bioavailab ility of a drug.

Biodegradable nanofibers were developed using Poly (L – lactic acid) and Soy protein for the delivery of an ayurvedic drug, Nardostachys jatamansi. A weighed quantity of powdered drug – Nardostachys Jatamansi was subjected to Soxhlet extraction using water and ethanol in equal quantities. Various blends of the drug extract and soy protein solution are prepared and mixed in Poly (L-lactic acid). Nanofibers of Soy Protein – Poly ...


Neuralsta: A Software Tool For Neural Stimulation And Recording Applications With A Laser Control, Rimi Sahu Dec 2011

Neuralsta: A Software Tool For Neural Stimulation And Recording Applications With A Laser Control, Rimi Sahu

Theses

The subject of this thesis is a software tool created in Matlab ® for neural stimulation and recording of the evoked potentials. The stimulation output can be delivered in electrical units for immediate use for neural stimulation or as a power control signal to a laser. NeuralSTA is designed to generate arbitrary waveforms of stimulation and simultaneously record the neural response while implementing the spike triggered averaging (STA) method, hence the name NeuralSTA. The output (stimulation) signal can be created in monophasic, biphasic or inverted monophasic forms (for laser control applications). Controls for pulse modulation allow shaping of the pulse waveform ...


Theoretical Prediction Of Joint Reaction Force In A Dynamic General 3-D Pendulum Tree Model For Human Or Animal Motion, Sucheta Goyal Dec 2011

Theoretical Prediction Of Joint Reaction Force In A Dynamic General 3-D Pendulum Tree Model For Human Or Animal Motion, Sucheta Goyal

Theses

Lagrangian dynamics and the method of superfluous coordinates are applied to predict dynamic joint reaction forces in an idealized flexible model of a branched 3-D pendulum tree system. The number of segments and joints on the tree are adjustable as is the branching tree pattern. The segments that comprise the tree are assumed to be one- dimensional rigid rods containing a discrete set of mass points that is both flexible in number and distribution on the tree. The idealized 3-D pendulum tree system is intended to provide a flexible theoretical framework to model and better understand the dynamics of human ...


Development Of 3-D Liver Model For Drug Screening Applications, Divya Rajendran Dec 2011

Development Of 3-D Liver Model For Drug Screening Applications, Divya Rajendran

Theses

The need for a an in vitro drug screening system that mimics the structural organization of natural liver for multi-functionality and maintenance of hepatocytes has become vital in the drug development process. The objective of this study was to engineer a three-dimensional (3-D) liver model using chitosan-based nanofiber scaffolds and co-culture system (adult rat hepatocytes and 3T3-J2 fibroblasts) to mimic the natural liver and to justify its application for in vitro drug screening. Chitosan nanofiber scaffolds were fabricated by electrospinning technique. In order to promote cell adhesion on the chitosan scaffolds, the scaffolds were coated with a cell adhesion molecule ...


Alendronate Treatment Elicits A Reduction In Fatigue-Life Of Canine Cortical Bone, Joseph Ryan Geissler Dec 2011

Alendronate Treatment Elicits A Reduction In Fatigue-Life Of Canine Cortical Bone, Joseph Ryan Geissler

Theses

Bone serves contradictory needs; bone must be strong yet light, and stiff yet flexible. At the tissue level bone material withstands cyclic loading without failing by dissipating energy via the formation and accumulation of microdamage. Proper removal of this damage in exchange for fresh tissue is vital to bone maintenance, and is achieved through a remodeling process. Imbalanced remodeling leads to osteoporotic fractures. Bisphosphonate drugs are proven to reduce fracture risk. However, the long-term effects of bisphosphonates on tissue-level properties are unknown. This study characterized the fatigue-life of cortical bone tissue after bisphosphonate treatment with alendronate (Aln). 1 1th ribs ...


Computer-Aided, Multi-Modal, And Compression Diffuse Optical Studies Of Breast Tissue, David R. Busch Jr Dec 2011

Computer-Aided, Multi-Modal, And Compression Diffuse Optical Studies Of Breast Tissue, David R. Busch Jr

Publicly Accessible Penn Dissertations

Diffuse Optical Tomography and Spectroscopy permit measurement of important physiological parameters non-invasively through ~10 cm of tissue. I have applied these techniques in measurements of human breast and breast cancer. My thesis integrates three loosely connected themes in this context: multi-modal breast cancer imaging, automated data analysis of breast cancer images, and microvascular hemodynamics of breast under compression. As per the first theme, I describe construction, testing, and the initial clinical usage of two generations of imaging systems for simultaneous diffuse optical and magnetic resonance imaging. The second project develops a statistical analysis of optical breast data from many spatial ...


Enhancing Meniscus Repair Through Biomaterial Design, Lara Ionescu Silverman Dec 2011

Enhancing Meniscus Repair Through Biomaterial Design, Lara Ionescu Silverman

Publicly Accessible Penn Dissertations

The knee meniscus is prone to damage, which leads to pain and inhibits mobility in the joint long term. Due to the minimal vascularity, low cellularity and large mechanical forces imparted on the meniscus with normal use, endogenous repair is limited. Resection of the damaged region of the tissue (meniscectomy) remains the most common treatment for a torn meniscus, but this procedure results in cartilage degradation and other adverse changes in the knee joint. Given the prevalence of meniscus damage, there is thus a pressing need for novel approaches to meniscus repair. To address this issue, this thesis developed in ...


Optimization And Translation Of Msc-Based Hyaluronic Acid Hydrogels For Cartilage Repair, Isaac E. Erickson Dec 2011

Optimization And Translation Of Msc-Based Hyaluronic Acid Hydrogels For Cartilage Repair, Isaac E. Erickson

Publicly Accessible Penn Dissertations

Traumatic injury and disease disrupt the ability of cartilage to carry joint stresses and, without an innate regenerative response, often lead to degenerative changes towards the premature development of osteoarthritis. Surgical interventions have yet to restore long-term mechanical function. Towards this end, tissue engineering has been explored for the de novo formation of engineered cartilage as a biologic approach to cartilage repair. Research utilizing autologous chondrocytes has been promising, but clinical limitations in their yield have motivated research into the potential of mesenchymal stem cells (MSCs) as an alternative cell source. MSCs are multipotent cells that can differentiate towards a ...


Strider, George Cummings, Brian Kreidle, Ricky Lee, Clark Steen Dec 2011

Strider, George Cummings, Brian Kreidle, Ricky Lee, Clark Steen

Mechanical Engineering

No abstract provided.


A Novel Free Form Femoral Cutting Guide, Wesley Andrew Underwood Dec 2011

A Novel Free Form Femoral Cutting Guide, Wesley Andrew Underwood

Masters Theses

Knee arthoplasty is a common procedure that requires the removal of damaged bone and cartilage from the distal femur so that a reconstructive implant may be installed. Traditionally, a five planar resection has been accomplished with a universal cutting box and navigated with either metal jigs or optically tracked computer navigation systems. Free form, or curved, resections have been made possible with surgical robots which control the resection pathway and serve as the navigation system. The free form femoral cutting guide serves as a non powered framework to guide a standard surgical drill along an anatomically defined pathway, resulting in ...


Simulating Ingress And Egress Motion For Heavy Earthmoving Machines, Hyun Jung Kwon Dec 2011

Simulating Ingress And Egress Motion For Heavy Earthmoving Machines, Hyun Jung Kwon

Theses and Dissertations

Design of heavy earthmoving equipment is based primarily on feedback from drivers. Most design studies on ingress and egress focus on the motion itself and rely heavily on experimental data. This process requires physical construction of expensive (in terms of time and money) mockups before any feedback can be obtained. Post-feedback design changes and the analysis of those changes are again expensive processes. Although the design of heavy vehicles requires consideration of human safety and comfort, very little attention has been given to simulating ingress and egress movement for these vehicles. This thesis describes the development of a virtual model ...


Truthmarker: A Tablet-Based Approach For Rapid Image Annotation, Mark Allen Christopher Dec 2011

Truthmarker: A Tablet-Based Approach For Rapid Image Annotation, Mark Allen Christopher

Theses and Dissertations

The development of automated techniques for the analysis of image data is an important and active area of research. To make progress, this research requires annotations of image data to build and validate models used for analysis. Given this requirement, the development of software tools that streamline the collection of annotations would be of great benefit to image analysis researchers. Such tools should meet the following requirements: rapid generation of annotations for large data sets, annotation and data management that is straightforward for users, flexibility for application to many diverse image datasets, configurability to allow the collection of annotations to ...


Course Of Illness And The Development Of Vascular Disease In Individuals With Bipolar Disorder, Jess G. Fiedorowicz Dec 2011

Course Of Illness And The Development Of Vascular Disease In Individuals With Bipolar Disorder, Jess G. Fiedorowicz

Theses and Dissertations

For over a century, there have been suggestions of a link between what is currently called bipolar disorder and cardiovascular mortality. In the contemporary epidemiological literature, this risk has been confirmed and approximates twice that expected based on age and gender. To date, however, this information has come primarily from clinical samples, which carry considerable risk of selection bias. The studies contained in this dissertation sought to assess this relationship using methods less vulnerable to selection bias and to determine the role that course of illness and treatments for illness may play in the development of vascular disease. In a ...


Indication Specific Treatment Modalities For Spinal Disorders - A Comprehensive Biomechanical Investigation, Aditya Vikas Ingalhalikar Dec 2011

Indication Specific Treatment Modalities For Spinal Disorders - A Comprehensive Biomechanical Investigation, Aditya Vikas Ingalhalikar

Theses and Dissertations

The cause and best treatment option for mechanical low back pain due to disc degeneration remains unsolved, despite `spinal fusion' being the gold standard of surgical treatment, post conservative care, for a very long time. However, the potential drawbacks of spinal fusion and the ongoing evolution in the understanding of normal and symptomatic spine biomechanics, biology and mechanobiology in conjunction with the advancements in material sciences, and tissue engineering has led to a change in the clinical perspective towards treatment methodologies for spinal disorders. Clinically, a gradual shift in philosophy is being observed from a `one size fits all', i ...


Large Population Evaluation Of Contact Stress Exposure In Articular Joints For Prediction Of Osteoarthritis Onset And Progression, Andrew M. Kern Dec 2011

Large Population Evaluation Of Contact Stress Exposure In Articular Joints For Prediction Of Osteoarthritis Onset And Progression, Andrew M. Kern

Theses and Dissertations

Contact stress exposure is thought to play a significant role in many aspects of joint degradation and pathology. Effective and accurate contact stress computation in native or pathological subject specific joints is an important tool in determining the role of contact stress in OA onset and worsening as well as eventually developing and monitoring interventions to prevent joint degradation. In the past FEA modeling has allowed for studies to be completed which relate contact stress exposure human ankle joint to the presence of radiographic OA. While promising, contact FEA for subject specific models is significantly limited by the number of ...


A Follower Load As A Muscle Control Mechanism To Stabilize The Lumbar Spine, Byeong Sam Kim Dec 2011

A Follower Load As A Muscle Control Mechanism To Stabilize The Lumbar Spine, Byeong Sam Kim

Theses and Dissertations

Study Design: Computational analyses using optimization finite element (FE) models.

Objective: To determine the spinal muscle forces (MFs) creating compressive follower loads (CFL) in the lumbar spine in various sagittal postures and to investigate if such MFs can maintain the spinal stability.

Summary of Background Data: Biomechanical loads are known closely associated with spinal disorders. Normal spinal loads, however, remains poorly understood due to the lack of knowledge of the MF control mechanism for normal biomechanical functions.

Methods: 3-D optimization and FE models of the spinal system (trunk, lumbar spine, sacrum, pelvis, and 232 muscles) were developed and validated using ...


Biomechanical Effects Of Multi-Level Laminoplasty And Laminectomy: An Experimental And Finite Element Investigation, Swathi Kode Dec 2011

Biomechanical Effects Of Multi-Level Laminoplasty And Laminectomy: An Experimental And Finite Element Investigation, Swathi Kode

Theses and Dissertations

Cervical spondylotic myelopathy is the most common spinal cord disorder in persons over 55 years of age in North America and perhaps in the world. Surgical options are broadly classified into two categories namely, anterior and posterior approaches. This study focuses on the posterior based approach (i.e. laminectomy or laminoplasty) which is considered when multiple levels of the spine have to be decompressed or when most of the cord compression results from posterior pathological conditions. The external and internal behavior of the spine after laminoplasty and laminectomy has been evaluated using both experimental and computational methods. Computationally, a validated ...


Effect Of Size Reduction Parameters In Pharmaceutical Manufacturing Process, Brian Breneman Dec 2011

Effect Of Size Reduction Parameters In Pharmaceutical Manufacturing Process, Brian Breneman

Biomedical Engineering

Within pharmaceutical manufacturing, size reduction is one of the most extensively used and vital unit operations. Size reduction in tablet production is achieved primarily through milling procedures, which allows for attaining product uniformity, optimizing product solubility, and improving bioavailability. Additionally, powders with a narrow range of size distribution can obviate problems in downstream processing as pertains to blending, compression, and coating as well as improve drug performance1. The purpose this study was to characterize the effect of various size reduction parameters as a result of the pharmaceutical milling process on a lactose wet granulation formulation and chemically active extruded ...


Development Of A Dynamic In Vitro Model Of A Stented Blood Vessel To Evaluate The Effects Of Stent Strut Material Selection And Surface Coating On Smooth Muscle Cell Response, Bradley Winn Dec 2011

Development Of A Dynamic In Vitro Model Of A Stented Blood Vessel To Evaluate The Effects Of Stent Strut Material Selection And Surface Coating On Smooth Muscle Cell Response, Bradley Winn

All Dissertations

Cardiovascular disease is the leading cause of mortality in The United States and Europe, accounting for approximately half of all deaths. The most common form of cardiovascular disease is atherosclerosis, which is characterized by the formation of fatty atheromatous plaques that can grow to occlude the vessel lumen, thus causing ischemia distal to the occlusion. This is commonly treated using balloon angioplasty, which is usually done in conjunction with the deployment of a stent. Stent deployment helps hold the vessel open following the local injury caused by balloon inflation and prevents elastic recoil and subsequent negative remodeling. Stenting has been ...


Electrical Coupling Between Micropatterned Cardiomyocytes And Stem Cells, Zhen Ma Dec 2011

Electrical Coupling Between Micropatterned Cardiomyocytes And Stem Cells, Zhen Ma

All Dissertations

To understand how stem cells functionally couple with native cardiomyocytes is crucial for cell-based therapies to restore the loss of cardiomyocytes that occurs during heart infarction and other cardiac diseases. Due to the complexity of the in vivo environment, our knowledge of cell coupling is heavily dependent on cell-culture models. However, conventional in vitro studies involve undefined cell shapes and random length of cell-cell contacts in addition to the presence of multiple homotypic and heterotypic contacts between interacting cells. Thus, it has not been feasible to study electrical coupling corresponding to isolated specific types of cell contact modes.
To address ...


Design And Fabrication Of Nanofluidic Systems For Biomolecule Characterizations, Orain Ansel Hibbert Dec 2011

Design And Fabrication Of Nanofluidic Systems For Biomolecule Characterizations, Orain Ansel Hibbert

Theses and Dissertations

Nanofluidic channel systems were designed and fabricated by combining MEMS microfabrication with AFM nanolithography. In the fabrication process flow, photolithography was first utilized to pattern microfluidic channels and reservoirs on a 4" Pyrex substrate. Subsequently, atomic force microscopy (AFM) based nanolithography was used to mechanically fabricate nanochannels to connect the microreservoirs which formed the inlet and outlet of the nanofluidic system. A Tap190 Diamond-Like Carbon (DLC) AFM tip with a force constant of 48 N/m and a radius of less than 15 nm was used as the nanolithography tool. The resultant nanochannel ranges from 20 to 80 µm in ...


'Exploring The Potential Of Using Antimicrobial Peptides And Copper Nanoparticles In Tackling Surgical Site Infections', Sriram Sankar Dec 2011

'Exploring The Potential Of Using Antimicrobial Peptides And Copper Nanoparticles In Tackling Surgical Site Infections', Sriram Sankar

All Theses

Postoperative wound site infections remain a major source of illness with approximately 500,000 infections per year, among an estimated 27 million surgical procedures. Such infections account for approximately one quarter of the estimated 2 million nosocomial infections in the United States which causes about 90,000 deaths each year. More than 70% of the bacteria that causes such infections are resistant to at least one of the antibiotics and result in longer hospitalization; besides requiring second option treatments that may be less effective, more toxic and expensive. Hence, there is a frenetic search for alternatives and in this regard ...


Characterizing Mechanical Heterogeneity In Cardiovascular Cells, Sandra Deitch Dec 2011

Characterizing Mechanical Heterogeneity In Cardiovascular Cells, Sandra Deitch

All Dissertations

Most tissue-level mechanical models assume homogeneous mechanical properties within a single cell type. However, measurements of cellular mechanical properties show large variability in whole-cell mechanical properties between cells from a single population. This heterogeneity has been observed in many cell populations and with several measurement techniques but the sources are not yet fully understood. Cell mechanical properties are directly related to the composition and organization of the cytoskeleton, which is physically coupled to neighboring cells through adherens junctions and to underlying matrix scaffolds through focal adhesion complexes. As such, we believe that this high level of heterogeneity can be attributed ...


Interfacial Force Field Parameterization Using The Dual Force Field Charmm Program For The Accurate Simulation Of Peptide-Surface Interaction, Nadeem Vellore Dec 2011

Interfacial Force Field Parameterization Using The Dual Force Field Charmm Program For The Accurate Simulation Of Peptide-Surface Interaction, Nadeem Vellore

All Dissertations

Protein adsorption to solid material surfaces is a complex phenomenon and various factors play a role in controlling these processes. Inherent limitations to understand these biological interactions using experimental approaches alone have led to the possibility of exploring these systems using computational molecular simulation methodologies. Before confidence can be placed on these computational protocols, however, rigorous validation of the applicability of these methods to accurately represent protein adsorption processes is needed. In this research, we evaluated the use of all-atom empirical force field (FF) based simulations using the CHARMM simulation program and FF for the study of peptide adsorption processes ...


Comparative Study On Posture And Its Influences On Horizontal Ground Reaction Forces Generated By Muscles: Implications For Crouch Gait, Hoa Xuan Hoang Dec 2011

Comparative Study On Posture And Its Influences On Horizontal Ground Reaction Forces Generated By Muscles: Implications For Crouch Gait, Hoa Xuan Hoang

Masters Theses

Crouch gait decreases walking efficiency due to the increased knee and hip flexion during the stance phase of gait. Crouch gait is generally considered to be disadvantageous for patients with cerebral palsy; however, a crouched posture may afford biomechanical advantages that lead some patients to adopt a crouch gait.

To investigate one possible advantage of crouch gait, a musculoskeletal model created in OpenSim was placed in 15 different postures from upright to severe crouch during initial, middle, and final stance of the gait cycle. A series of optimizations were performed for each posture to maximize ground reaction forces for the ...


A Computational Investigation For Potential Improvements, Angela Grujicic Dec 2011

A Computational Investigation For Potential Improvements, Angela Grujicic

All Theses

Mild traumatic brain injury (mTBI), colloquially known as a concussion, is the most common injury in modern wars. This domination of mTBI is hypothesized to be due to a combination of unconventional explosives and better protection and care of the patients, increasing survivability. While the majority of the body is covered in armor, the head is left relatively unprotected. The current Advanced Combat Helmet (ACH) has been designed to protect the warfighter against ballistic impacts and impacts against a hard surface, with little to no regard to blast loading. Polyureas, a class of microsegregated, elastomeric copolymers, has been shown to ...


Impedance-Based Detection Of Tissue Using A Multi-Electrode Device, Shane Killian Fleshman Dec 2011

Impedance-Based Detection Of Tissue Using A Multi-Electrode Device, Shane Killian Fleshman

Master's Theses and Project Reports

Melanoma skin cancer is the abnormal growth of the melanocytes – the pigmented cells located in the epidermis. The current gold standard diagnostic technique for determining whether a lesion is cancerous involves subjectively examining suspicious lesions and performing an invasive biopsy to confirm melanoma. This method may neglect some lesions or cause scarring from biopsies that turn out to be benign. Thus, impedance-based detection using a multi-electrode device was investigated as a noninvasive technique to diagnose melanoma skin cancer. The multi-electrode device was designed with 8 equally spaced Ag/AgCl electrodes surrounding one central electrode at a 5 mm radius. The ...