Engineering Commons^™

Relationship Between The Foveal Avascular Zone And Foveal Pit Morphology, Adam M. Dubis, Benjamin R. Hansen, Robert F. Cooper, Joseph Beringer, Alfredo Dubra, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Purpose. To assess the relationship between foveal pit morphology and size of the foveal avascular zone (FAZ).

Methods. Forty-two subjects were recruited. Volumetric images of the macula were obtained using spectral domain optical coherence tomography. Images of the FAZ were obtained using either a modified fundus camera or an adaptive optics scanning light ophthalmoscope. Foveal pit metrics (depth, diameter, slope, volume, and area) were automatically extracted from retinal thickness data, whereas the FAZ was manually segmented by two observers to extract estimates of FAZ diameter and area.

Results. Consistent with previous reports, the authors observed significant variation in foveal pit …

Subclinical Photoreceptor Disruption In Response To Severe Head Trauma, Kimberly E. Stepien, Wanda M. Martinez, Adam M. Dubis, Robert F. Cooper, Alfredo Dubra, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Commotio retinae is a transient opacification of the retina due to outer retinal disruption occurring in a contrecoup fashion after blunt trauma.Histological studies in animals and humans after ocular blunt trauma have revealed that disruption occurs at the level of the photoreceptor outer segments and retinal pigment epithelium.Recent reports using optical coherence tomography (OCT) have shown detectable disruption at the level of the photoreceptor inner segment/outer segment junction and retinal pigment epithelium and that these changes may be reversible over time with restoration of normal outer retinal architecture.However, the resolution of existing OCT technology may not be sensitive enough to …

Damage To Mitochondrial Complex I During Cardiac Ischemia Reperfusion Injury Is Reduced Indirectly By Anti-Anginal Drug Ranolazine, Ashish K. Gadicherla, David F. Stowe, William E. Antholine, Meiying Yang, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

Ranolazine, an anti-anginal drug, is a late Na⁺ channel current blocker that is also believed to attenuate fatty acid oxidation and mitochondrial respiratory complex I activity, especially during ischemia. In this study, we investigated if ranolazine's protective effect against cardiac ischemia/reperfusion (IR) injury is mediated at the mitochondrial level and specifically if respiratory complex I (NADH Ubiquinone oxidoreductase) function is protected. We treated isolated and perfused guinea pig hearts with ranolazine just before 30 min ischemia and then isolated cardiac mitochondria at the end of 30 min ischemia and/or 30 min ischemia followed by 10 min reperfusion. We utilized …

Enhanced Charge-Independent Mitochondrial Free Ca2+ And Attenuated Adp-Induced Nadh Oxidation By Isoflurane: Implications For Cardioprotection, Bhawana Agarwal, Amadou K.S. Camara, David F. Stowe, Zeljko J. Bosnjak, Ranjan K. Dash

Biomedical Engineering Faculty Research and Publications

Modulation of mitochondrial free Ca^{2 +} ([Ca^{2 +}]_m) is implicated as one of the possible upstream factors that initiates anesthetic-mediated cardioprotection against ischemia–reperfusion (IR) injury. To unravel possible mechanisms by which volatile anesthetics modulate [Ca^{2 +}]_m and mitochondrial bioenergetics, with implications for cardioprotection, experiments were conducted to spectrofluorometrically measure concentration-dependent effects of isoflurane (0.5, 1, 1.5, 2 mM) on the magnitudes and time-courses of [Ca^{2 +}]_m and mitochondrial redox state (NADH), membrane potential (ΔΨ_m), respiration, and matrix volume. Isolated mitochondria from rat hearts were energized with 10 …

Adding Ros Scavengers To Cold K+ Cardioplegia Reduces Superoxide Emission During 2 H Global Cold Cardiac Ischemia, Mohammed Aldakkak, David F. Stowe, James S. Heisner, Matthias L. Riess, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

We reported that the combination of reactive oxygen species (ROS) quenchers Mn(III) tetrakis (4-benzoic acid) porphyrin (MnTBAP), catalase, and glutathione (MCG) given before 2 hours cold ischemia better protected cardiac mitochondria against cold ischemia and warm reperfusion (IR)-induced damage than MnTBAP alone. Here, we hypothesize that high K⁺ cardioplegia (CP) plus MCG would provide added protection of mitochondrial bioenergetics and cardiac function against IR injury. Using fluorescence spectrophotometry, we monitored redox balance, ie reduced nicotinamide adenine dinucleotide and flavin adenine dinucleotide (NADH/FAD), superoxide (O₂ ^•−), and mitochondrial Ca²⁺ (m[Ca²⁺]) in the left ventricular free …

Persistent Vascular Collagen Accumulation Alters Hemodynamic Recovery From Chronic Hypoxia, Diana M. Tabima, Alejandro Roldan-Alzate, Zhijie Wang, Timothy A. Hacker, Robert C. Molthen, Naomi C. Chesler

Biomedical Engineering Faculty Research and Publications

Pulmonary arterial hypertension (PAH) is caused by narrowing and stiffening of the pulmonary arteries that increase pulmonary vascular impedance (PVZ). In particular, small arteries narrow and large arteries stiffen. Large pulmonary artery (PA) stiffness is the best current predictor of mortality from PAH. We have previously shown that collagen accumulation leads to extralobar PA stiffening at high strain (Ooi et al. 2010). We hypothesized that collagen accumulation would increase PVZ, including total pulmonary vascular resistance (Z₀), characteristic impedance (Z_C), pulse wave velocity (PWV) and index of global wave reflections (P_b/P …

The Latest Lessons Learned From Retrieval Analyses Of Ultra-High Molecular Weight Polyethylene, Metal-On-Metal, And Alternative Bearing Total Disc Replacements, Steven M. Kurtz, Jeffrey M. Toth, Ryan Siskey, Lauren Ciccarelli, Daniel Macdonald, Jorge Isaza, Todd Lanman, Ilona Punt, Marla Marla Steinbeck, Jan Goffin, André Van Ooij

Biomedical Engineering Faculty Research and Publications

Knowledge regarding the in vivo performance and periprosthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following 4 main questions: (1) What are the latest lessons learned from using polyethylene in large joints and how are they relevant to current TDRs? (2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal cobalt-chrome bearings in large joints and how are they relevant to current TDRs? (3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for …

Dc Dielectrophoretic Assisted Anti-Fouling Filtration System, Nathan M. Cohen

Master's Theses

Filtration processes, whether on the microfluidic, clinical treatment systems, or industrial scale (e.g., point-of-care diagnostics, dialysis, and biopharmaceutical manufacturing, respectively), are often inseparable from membrane clogging (fouling). As a consequence, most, if not all, filtration systems require frequent maintenance to maintain functionality and efficiency. The thesis of this project hypothesizes that Dielectrophoresis can be combined with standard filtration to reduce filter fouling, extending membrane life, and enabling continuous operation. This project investigates a method to reduce fouling, add specificity and efficiency, and decrease the cost and challenge of filtration based biofluid separations.

To substantiate this thesis, we designed, fabricated, and …

Development Of A Standardized Method For Comparing Biomechanical Properties Of Various Sternal Closure Techniques, Ramzi P. Hawit

Master's Theses

Background:

33.6% of all deaths in America are caused by cardiovascular disease. An estimated 82.6 million adults (>1 in 3) in America have some form of cardiovascular disease. There were over 400,000 bypass surgeries requiring open-heart surgery. Sternal dehiscence is associated with a morbidity rate of over 47% if mediastinitis supervenes. A rigid closure is required to avoid healing complications, and wire, plates, and bands are all used in an attempt to make a better closure. The purpose of this study it to compare multiple closures and validate a new testing method.

Methods:

Polyurethane foam blocks will be used, …

Novel On-Demand Droplet Generation For Selective Fluid Sample Extraction, Melinda Simon, Jeffrey Fisher, Melinda Simon, Abraham Lee

Faculty Publications

 A novel microfluidic device enabling selective generation of droplets and encapsulation of targets is presented. Unlike conventional methods, the presented mechanism generates droplets with unique selectivity by utilizing a K-junction design. The K-junction is a modified version of the classic T-junction with an added leg that serves as the exit channel for waste. The dispersed phase fluid enters from one diagonal of the K and exits the other diagonal while the continuous phase travels in the straight leg of the K. The intersection forms an interface that allows the dispersed phase to be controllably injected through actuation of an elastomer …

A Multifaceted Analysis Of Early Stage Non-Small Cell Lung Cancer Data, Madhusmita Behera

USF Tampa Graduate Theses and Dissertations

Some early stage NSCLC patients have a better survival prospects than others. In any event, the long-term prognosis for NSCLC patients is poor. Various measures were investigated to gain a better understanding of those patient characteristics that confer better survival or predict disease recurrence. A dataset comprised of stage 1 NSCLC patients (n=162) that underwent resection was investigated. Clinical variables (CVs) and tissue microarray (TMA) images with DNA repair protein and standard H&E expressions were investigated. Patients were dichotomized into two groups by survival characteristics and logistic regression (LR) modeling was used to predict favorable survival outcome. Various patient strata …

New Window On Optical Brain Imaging; Medical Development, Simulations And Applications, Chemseddine Mansouri, Nasser H. Kashou

Biomedical, Industrial & Human Factors Engineering Faculty Publications

In this chapter we hope to give a technological review of near-infrared light and systems, discuss optode design considerations including background on the fiber design as it relates to this field and finally touch on current trends and applications. For the latter, we will focus on diffusion theory and simulation of photon propagation using a head model. We will follow this with concluding remarks.

Sendai Virus-Based Liposomes Enable Targeted Cytosolic Delivery Of Nanoparticles In Brain Tumor-Derived Cells, Veronica Dudu, Veronica Rotari, Maribel Vazquez

Publications and Research

BACKGROUND: Nanotechnology-based bioassays that detect the presence and/or absence of a combination of cell markers are increasingly used to identify stem or progenitor cells, assess cell heterogeneity, and evaluate tumor malignancy and/or chemoresistance. Delivery methods that enable nanoparticles to rapidly detect emerging, intracellular markers within cell clusters of biopsies will greatly aid in tumor characterization, analysis of functional state and development of treatment regimens.

RESULTS: Experiments utilized the Sendai virus to achieve in vitro, cytosolic delivery of Quantum dots in cells cultured from Human brain tumors. Using fluorescence microscopy and Transmission Electron Microscopy, in vitro experiments illustrated that these virus-based …

Quantitative Cherenkov Emission Spectroscopy For Tissue Oxygenation Assessment, Johan Axelsson, Adam K. Glaser, David J. Gladstone, Brian W. Pogue

Dartmouth Scholarship

Measurements of Cherenkov emission in tissue during radiation therapy are shown to enable estimation of hemoglobin oxygen saturation non-invasively, through spectral fitting of the spontaneous emissions from the treated tissue. Tissue oxygenation plays a critical role in the efficacy of radiation therapy to kill tumor tissue. Yet in-vivo measurement of this has remained elusive in routine use because of the complexity of oxygen measurement techniques. There is a spectrally broad emission of Cherenkov light that is induced during the time of irradiation, and as this travels through tissue from the point of the radiation deposition, the tissue absorption and scatter …

Determination Of Effective Training Methods To Learn A Laparoscopic Camera Navigation Task Under Stressful Environments, Devnath Vasudevan

Theses and Dissertations

Stress in surgical environment is generally very high and can result in performance degradation increasing patient risk .Current Training systems for learning minimally invasive surgical skills do not consider the component of stress in their training model. In this study the focus was on developing alternative training models that would allow the learner to effectively perform minimally invasive skill under stress. Two alternate training methods: 1) Training under stress until high performance levels and 2) training until high performance and low cognitive load are achieved were considered for this study. The control group consisted of training under no stress and …

Fabrication Of Biocompatible, Vibrational Magnetoelastic Materials For Controlling Cellular Adhesion, Hal Holmes, Ee Lim Tan, Keat Ghee Ong, Rupak Rajachar

Michigan Tech Publications, Part 1

This paper describes the functionalization of magnetoelastic (ME) materials with Parylene-C coating to improve the surface reactivity to cellular response. Previous study has demonstrated that vibrating ME materials were capable of modulating cellular adhesion when activated by an externally applied AC magnetic field. However, since ME materials are not inherently biocompatible, surface modifications are needed for their implementation in biological settings. Here, the long-term stability of the ME material in an aqueous and biological environment is achieved by chemical-vapor deposition of a conformal Parylene-C layer, and further functionalized by methods of oxygen plasma etching and protein adsorption. In vitro cytotoxicity …

Magnetic Resonance Elastography Methodology For The Evaluation Of Tissue Engineered Construct Growth., Evan Curtis, Simeng Zhang, Vahid Khalilzad-Sharghi, Thomas Boulet, Shadi F. Othman

All Faculty Articles - School of Engineering and Computer Science

Traditional mechanical testing often results in the destruction of the sample, and in the case of long term tissue engineered construct studies, the use of destructive assessment is not acceptable. A proposed alternative is the use of an imaging process called magnetic resonance elastography. Elastography is a nondestructive method for determining the engineered outcome by measuring local mechanical property values (i.e., complex shear modulus), which are essential markers for identifying the structure and functionality of a tissue. As a noninvasive means for evaluation, the monitoring of engineered constructs with imaging modalities such as magnetic resonance imaging (MRI) has seen increasing …

Biomolecular Mechanisms And Functional Characterization Of Nanomaterials In Programmed Cancer Cell Death For Potential Applications In Medicine, Biomedical Sciences, And Bioengineering, Md. Zakir Hossain

Theses and Dissertations

Cancer bionanotechnology is an interdisciplinary area of research in applied biosciences, biomedical engineering, and nano-medicine. Currently, apoptotic cell death inducers and regulators are considered to have significant potential for cancer therapy. The ability to escape apoptosis is one of the key properties of human cancer. Pancreatic cancer that has the highest fatality rates of all cancers is prompt to evade apoptosis. Nanomaterials like Ni NWs have various novel properties that could be very useful in bio-medical applications at the molecular and cellular levels. The overall objective of this research was to investigate the antiproliferative and apoptogenic properties of Ni NWs …

Locomotor Adaptation To Resistance During Treadmill Training Transfers To Overground Walking In Human Sci, Sheng-Che Yen, Brian D. Schmit, Jill M. Landry, Heidi Roth, Ming Wu

Biomedical Engineering Faculty Research and Publications

Treadmill training has been used as a promising technique to improve overground walking in patients with spinal cord injury (SCI). Previous findings showed that a gait pattern may adapt to a force perturbation during treadmill training and show aftereffects following removal of the force perturbation. We hypothesized that aftereffects would transfer to overground walking to a greater extent when the force perturbation was resisting rather than assisting leg swing during treadmill training. Ten subjects with incomplete SCI were recruited into this study for two treadmill training sessions: one using swing resistance and the other using swing assistance during treadmill stepping. …

An Empirical Method For Correcting The Detector Spectral Response In Energy-Resolved Ct, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Energy-resolving photon-counting detectors have the potential for improved material decomposition compared to dual-kVp approaches. However, material decomposition accuracy is limited by the nonideal spectral response of the detectors. This work proposes an empirical method for correcting the nonideal spectral response, including spectrum-tailing effects. Unlike previous correction methods which relied on synchrotron measurements, the proposed method can be performed on the scanner. The proposed method estimates a spectral-response matrix by performing x-ray projection measurements through a range of known thicknesses of two or more calibration materials. Once estimated, the spectral-response matrix is incorporated into conventional material decomposition algorithms. A simulation study …

A Laplace Pressure Based Microfluidic Trap For Passive Droplet Trapping And Controlled Release, Melinda Simon, Robert Lin, Jeffrey Fisher, Abraham Lee

Faculty Publications

Here, we present a microfluidic droplet trap that takes advantage of the net Laplace pressure force generated when a droplet is differentially constricted. Mathematical simulations were first used to understand the working range of the component; followed by finite element modeling using the CFDsoftware package to further characterize the behavior of the system. Controlled release of the trapped droplets is also demonstrated through both a mechanical method and a chemical method that manipulates the total pressure exerted on the trapped droplet. The unique design of this trapping device also provides the capability for selection of a single dropletfrom a train, …

Biomechanics, Brooke A. Slavens, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Biomechanics is a vast discipline within the field of Biomedical Engineering. It explores the underlying mechanics of how biological and physiological systems move. It encompasses important clinical applications to address questions related to medicine using engineering mechanics principles. Biomechanics includes interdisciplinary concepts from engineers, physicians, therapists, biologists, physicists, and mathematicians. Through their collaborative efforts, biomechanics research is ever changing and expanding, explaining new mechanisms and principles for dynamic human systems. Biomechanics is used to describe how the human body moves, walks, and breathes, in addition to how it responds to injury and rehabilitation. Advanced biomechanical modeling methods, such as inverse …

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 through …

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, …

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

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 …

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 …

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 …

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, …

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 …