Biomedical Engineering and Bioengineering Commons^™

Mitigation Of Radiation Induced Pulmonary Vascular Injury By Delayed Treatment With Captopril, Robert C. Molthen, Qingping Wu, Brian L. Fish, John E. Moulder, Elizabeth R. Jacobs, Meetha M. Medhora

Biomedical Engineering Faculty Research and Publications

Background and Objective: A single dose of 10 Gy radiation to the thorax of rats results in decreased total lung angiotensin-converting enzyme (ACE) activity, pulmonary artery distensibility and distal vascular density while increasing pulmonary vascular resistance (PVR) at 2 months post-exposure. In this study, we evaluate the potential of a renin-angiotensin system (RAS) modulator, the ACE inhibitor captopril, to mitigate this pulmonary vascular damage.

Methods: Rats exposed to 10 Gy thorax only irradiation and age-matched controls were studied 2 months after exposure, during the development of radiation pneumonitis. Rats were treated, either immediately or 2 weeks after radiation exposure, with …

First-Order Design Of A Reflective Viewfinder For Adaptive Optics Ophthalmoscopy, Alfredo Dubra, Yusufu N. Sulai

Biomedical Engineering Faculty Research and Publications

Adaptive optics (AO) ophthalmoscopes with small fields of view have limited clinical utility. We propose to address this problem in reflective instruments by incorporating a viewfinder pupil relay designed by considering pupil and image centering and conjugation. Diverting light from an existing pupil optical relay to the viewfinder relay allows switching field of view size. Design methods that meet all four centering and conjugation conditions using either a single concave mirror or with two concave mirrors forming an off-axis afocal telescope are presented. Two different methods for calculating the focal length and orientation of the concave mirrors in the afocal …

Tyrosine Nitration Of Voltage-Dependent Anion Channels In Cardiac Ischemia-Reperfusion: Reduction By Peroxynitrite Scavenging, Meiying Yang, Amadou K.S. Camara, Bassam T. Wakim, Yifan Zhou, Ashish K. Gadicherla, Wai-Meng Kwok, David F. Stowe

Biomedical Engineering Faculty Research and Publications

Excess superoxide (O₂⁻) and nitric oxide (NO) forms peroxynitrite (ONOO⁻) during cardiac ischemia reperfusion (IR) injury, which in turn induces protein tyrosine nitration (tyr-N). Mitochondria are both a source of and target for ONOO⁻. Our aim was to identify specific mitochondrial proteins that display enhanced tyr-N after cardiac IR injury, and to explore whether inhibiting O₂⁻/ONOO⁻ during IR decreases mitochondrial protein tyr-N and consequently improves cardiac function. We show here that IR increased tyr-N of 35 and 15 kDa mitochondrial proteins using Western blot analysis with 3-nitrotyrosine antibody. Immunoprecipitation …

Functional Classification Of Skeletal Muscle Networks. Ii. Applications To Pathophysiology, Yu Wang, Jack Winters, Shankar Subramaniam

Biomedical Engineering Faculty Research and Publications

In our preceding companion paper (Wang Y, Winters J, Subramaniam S. J Appl Physiol. doi: 10.1152/japplphysiol.01514.2011), we used extensive expression profile data on normal human subjects, in combination with legacy knowledge to classify skeletal muscle function into four models, namely excitation-activation, mechanical, metabolic, and signaling-production model families. In this paper, we demonstrate how this classification can be applied to study two well-characterized myopathies: amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD). Using skeletal muscle profile data from ALS and DMD patients compared with that from normal subjects, normal young in the case of DMD, we delineate molecular mechanisms …

Impairments In Sensorimotor Control During Pursuit And Compensatory Tracking In Individuals With Multiple Sclerosis, Scott A. Beardsley, Heenan M., Robert A. Scheidt, D. Woo, J. Bobholz

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Monosynaptic Functional Connectivity In Cerebral Cortex During Wakefulness And Under Graded Levels Of Anesthesia, Jeannette A. Vizuete, Siveshigan Pillay, Kamran Diba, Kristina M. Ropella, Anthony G. Hudetz

Biomedical Engineering Faculty Research and Publications

The balance between excitation and inhibition is considered to be of significant importance for neural computation and cognitive function. Excitatory and inhibitory functional connectivity in intact cortical neuronal networks in wakefulness and graded levels of anesthesia has not been systematically investigated. We compared monosynaptic excitatory and inhibitory spike transmission probabilities using pairwise cross-correlogram (CCG) analysis. Spikes were measured at 64 sites in the visual cortex of rats with chronically implanted microelectrode arrays during wakefulness and three levels of anesthesia produced by desflurane. Anesthesia decreased the number of active units, the number of functional connections, and the strength of excitatory connections. …

Design And Validation Of Bending Test Method For Characterization Of Miniature Pediatric Cortical Bone Specimens, Carolyne Albert, John Jameson, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Osteogenesis imperfecta is a genetic disorder of bone fragility; however, the effects of this disorder on bone material properties are not well understood. No study has yet measured bone material strength in humans with osteogenesis imperfecta. Small bone specimens are often extracted during routine fracture surgeries in children with osteogenesis imperfecta. These specimens could provide valuable insight into the effects of osteogenesis imperfecta on bone material strength; however, their small size poses a challenge to their mechanical characterization. In this study, a validated miniature three-point bending test is described that enables measurement of the flexural material properties of pediatric cortical …

Enhancing The Engineering Curriculum: Defining Discovery Learning At Marquette University, Jay R. Goldberg, Mark L. Nagurka

Biomedical Engineering Faculty Research and Publications

This paper summarizes the results of our investigation into the feasibility of increasing the level of discovery learning in the College of Engineering (COE) at Marquette University. We review the education literature, document examples of discovery learning currently practiced in the COE and other schools, and propose a Marquette COE-specific definition of discovery learn-ing. Based on our assessment of the benefits, costs, and tradeoffs associated with increasing the level of discovery learning, we pre-sent several recommendations and identify resources required for implementation. These recommendations may be helpful in enhancing engineering education at other schools.

Creep Evaluation Of (Orthotic) Cast Materials During Simulated Clubfoot Correction, T. L. Cohen, H. Altiok, Sergey Tarima, P. A. Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

The Ponseti method is a widely accepted and highly successful conservative treatment of pediatric clubfoot that relies on weekly manipulations and cast applications. However, the material behavior of the cast in the Ponseti technique has not been investigated. The current study sought to characterize the ability of two standard casting materials to maintain the Ponseti corrected foot position by evaluating creep response. A dynamic cast testing device (DCTD) was built to simulate a typical pediatric clubfoot. Semi-rigid fiberglass and rigid fiberglass casting materials were applied to the device, and the rotational creep was measured at various constant torques. The movement …

Chronically Inadequate Sleep Results In Abnormal Bone Formation And Abnormal Bone Marrow In Rats, Carol A. Everson, Anne E. Folley, Jeffrey M. Toth

Biomedical Engineering Faculty Research and Publications

Insufficient sleep over long durations of the lifespan is believed to adversely affect proper development and healthful aging, although how this might become manifested is unknown. In the present study, rats were repeatedly sleep-restricted during 72 days to permit maladaptations to evolve, thereby permitting study. Densitometric and histomorphometric analyses were performed on harvested bone. In sleep-restricted rats, bone lined by osteoid was reduced 45-fold and osteoid thickness was decreased, compared with controls. This corresponded to a decrease in osteoblast number and activity. The percentage of bone lined by osteoclasts did not differ from that of controls. Plasma concentrations of an …

Role Of Glutathione In Lung Retention Of 99mtc-Hexamethylpropyleneamine Oxime In Two Unique Rat Models Of Hyperoxic Lung Injury, Said H. Audi, David L. Roerig, Steven Thomas Haworth, Anne V. Clough

Biomedical Engineering Faculty Research and Publications

Rat exposure to 60% O₂ for 7 days (hyper-60) or to >95% O₂ for 2 days followed by a 24-hour in room air (hyper-95R) confers susceptibility or tolerance, respectively, of the otherwise lethal effects of subsequent exposure to 100% O₂. The objective of this study was to determine if lung retention of the radiopharmaceutical agent ^99mTc-HMPAO (hexamethylpropyleneamine oxime) is differentially altered in hyper-60 and hyper-95R rats. Tissue retention of HMPAO is dependent on intracellular content of the antioxidant glutathione (GSH) and mitochondrial function. HMPAO was injected i.v. in anesthetized rats and planar images were acquired. …

Upper Extremity Biomechanical Model For Evaluation Of Pediatric Joint Demands During Wheelchair Mobility, Alyssa J. Paul, Brooke A. Slavens, Adam Graf, Joseph Krzak, Lawrence Vogel, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Current methods for evaluating upper extremity (UE) dynamics during pediatric wheelchair use are limited. We propose a new model to characterize UE joint kinematics and kinetics during pediatric wheelchair mobility. The bilateral model is comprised of the thorax, clavicle, scapula, upper arm, forearm, and hand segments. The modeled joints include: sternoclavicular, acromioclavicular, glenohumeral, elbow and wrist. The model is complete and is currently undergoing pilot studies for clinical application. Results may provide considerable quantitative insight into pediatric UE joint dynamics to improve wheelchair prescription, training and long term care of children with orthopaedic disabilities.

Understanding The In Vivo Uptake Kinetics Of A Phosphatidylethanolamine-Binding Agent 99mTc-Duramycin, Said H. Audi, Zhixin Li, Joseph Capacete, Yu Liu, Wei Fang, Laura G. Shu, Ming Zhao

Biomedical Engineering Faculty Research and Publications

Introduction

^99mTc-Duramycin is a peptide-based molecular probe that binds specifically to phosphatidylethanolamine (PE). The goal was to characterize the kinetics of molecular interactions between ^99mTc-Duramycin and the target tissue.

Methods

High level of accessible PE is induced in cardiac tissues by myocardial ischemia (30 min) and reperfusion (120 min) in Sprague–Dawley rats. Target binding and biodistribution of ^99mTc-duramycin were captured using SPECT/CT. To quantify the binding kinetics, the presence of radioactivity in ischemic versus normal cardiac tissues was measured by gamma counting at 3, 10, 20, 60 and 180 min after injection. A partially inactivated form of …

Storage And Loss Moduli Of Bone In Osteogenesis Imperfecta (Oi), Carolyne Albert, John Jameson, Jeffrey Toth, Peter A. Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Identification Of Hemodynamically Optimal Coronary Stent Designs Based On Vessel Caliber, Timothy J. Gundert, Alison L. Marsden, Weiguang Yang, David S. Marks, John F. Ladisa

Biomedical Engineering Faculty Research and Publications

Coronary stent design influences local patterns of wall shear stress (WSS) that are associated with neointimal growth, restenosis, and the endothelialization of stent struts. The number of circumferentially repeating crowns N_C for a given stent de- sign is often modified depending on the target vessel caliber, but the hemodynamic implications of altering N_C have not previously been studied. In this investigation, we analyzed the relationship between vessel diameter and the hemodynamically optimal N_C using a derivative-free optimization algorithm coupled with computational fluid dynamics. The algorithm computed the optimal vessel diameter, defined as minimizing the area of stent-induced …

Adaptive Optics Scanning Ophthalmoscopy With Annular Pupils, Yusufu N. Sulai, Alfredo Dubra

Biomedical Engineering Faculty Research and Publications

Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing …

Robotic Resistance Treadmill Training Improves Locomotor Function In Human Spinal Cord Injury: A Pilot Study, Ming Wu, Jill M. Landry, Brian D. Schmit, T. George Hornby, Sheng-Che Yen

Biomedical Engineering Faculty Research and Publications

Objective

To determine whether cable-driven robotic resistance treadmill training can improve locomotor function in humans with incomplete spinal cord injury (SCI).

Design

Repeated assessment of the same patients with crossover design.

Setting

Research units of rehabilitation hospitals in Chicago.

Participants

Patients with chronic incomplete SCI (N=10) were recruited to participate in this study.

Interventions

Subjects were randomly assigned to 1 of 2 groups. One group received 4 weeks of assistance training followed by 4 weeks of resistance training, while the other group received 4 weeks of resistance training followed by 4 weeks of assistance training. Locomotor training was provided by …

Repeatability Of In Vivo Parafoveal Cone Density And Spacing Measurements, Robert Garrioch, Christopher S. Langlo, Adam M. Dubis, Robert F. Cooper, Alfredo Dubra, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Purpose. To assess the repeatability and measurement error associated with cone density and nearest neighbor distance (NND) estimates in images of the parafoveal cone mosaic obtained with an adaptive optics scanning light ophthalmoscope (AOSLO).

Methods. Twenty-one participants with no known ocular pathology were recruited. Four retinal locations, approximately 0.65[degrees] eccentricity from the center of fixation, were imaged 10 times in randomized order with an AOSLO. Cone coordinates in each image were identified using an automated algorithm (with or without manual correction) from which cone density and NND were calculated. Owing to naturally occurring fixational instability, the 10 images recorded from …

Within-Subject Joint Independent Component Analysis Of Simultaneous Fmri/Erp In An Auditory Oddball Paradigm, Jain Mangalathu-Arumana, Scott A. Beardsley, E. Liebenthal

Biomedical Engineering Faculty Research and Publications

The integration of event-related potential (ERP) and functional magnetic resonance imaging (fMRI) can contribute to characterizing neural networks with high temporal and spatial resolution. This research aimed to determine the sensitivity and limitations of applying joint independent component analysis (jICA) within-subjects, for ERP and fMRI data collected simultaneously in a parametric auditory frequency oddball paradigm. In a group of 20 subjects, an increase in ERP peak amplitude ranging 1–8 μV in the time window of the P300 (350–700 ms), and a correlated increase in fMRI signal in a network of regions including the right superior temporal and supramarginal gyri, was …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

Upper Extremity Kinematics In Children With Spinal Cord Injury During Wheelchair Mobility, Brooke Slavens, Alyssa Paul, Adam Graf, Joseph Krzak, Lawrence Vogel, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.