Biomedical Engineering and Bioengineering Commons^™

Different Motion Cues Are Used To Estimate Time-To-Arrival For Frontoparallel And Loming Trajectories, Finnegan J. Calabro, Scott A. Beardsley, Lucia M. Vaina

Biomedical Engineering Faculty Research and Publications

Estimation of time-to-arrival for moving objects is critical to obstacle interception and avoidance, as well as to timing actions such as reaching and grasping moving objects. The source of motion information that conveys arrival time varies with the trajectory of the object raising the question of whether multiple context-dependent mechanisms are involved in this computation. To address this question we conducted a series of psychophysical studies to measure observers’ performance on time-to-arrival estimation when object trajectory was specified by angular motion (“gap closure” trajectories in the frontoparallel plane), looming (colliding trajectories, TTC) or both (passage courses, TTP). We measured performance …

Mechanical Characterization Of Fourth Generation Composite Humerus, Prateek Grover, Carolyne Albert, Mei Wang, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Mechanical data on upper extremity surrogate bones, supporting use as biomechanical tools, is limited. The objective of this study was to characterize the structural behaviour of the fourth-generation composite humerus under simulated physiologic bending, specifically, stiffness, rigidity, and mid-diaphysial surface strains. Three humeri were tested in four-point bending, in anatomically defined anteroposterior (AP) and mediolateral (ML) planes. Stiffness and rigidity were derived using load–displacement data. Principal strains were determined at the anterior, posterior, medial, and lateral surfaces in the humeral mid-diaphysial transverse plane of one specimen using stacked rosettes. Linear structural behaviour was observed within the test range. Average stiffness …

Quantifying The Tibiofemoral Joint Space Using X-Ray Tomosynthesis, Benjamin Kalinosky, John M. Sabol, Kelly Piacsek, Beth Heckel, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose: Digital x-ray tomosynthesis (DTS) has the potential to provide 3D information about the knee joint in a load-bearing posture, which may improve diagnosis and monitoring of knee osteoarthritis compared with projection radiography, the current standard of care. Manually quantifying and visualizing the joint space width (JSW) from 3D tomosynthesis datasets may be challenging. This work developed a semiautomated algorithm for quantifying the 3D tibiofemoral JSW from reconstructed DTS images. The algorithm was validated through anthropomorphic phantom experiments and applied to three clinical datasets. Methods: A user-selected volume of interest within the reconstructed DTS volume was enhanced with 1D multiscale …

Effect Of Sensory Feedback From The Proximal Upper Limb On Voluntary Isometric Finger Flexion And Extension In Hemiparetic Stroke Subjects, Gilles Hoffmann, Brian D. Schmit, Jennifer H. Kahn, Derek G. Kamper

Biomedical Engineering Faculty Research and Publications

This study investigated the potential influence of proximal sensory feedback on voluntary distal motor activity in the paretic upper limb of hemiparetic stroke survivors and the potential effect of voluntary distal motor activity on proximal muscle activity. Ten stroke subjects and 10 neurologically intact control subjects performed maximum voluntary isometric flexion and extension, respectively, at the metacarpophalangeal (MCP) joints of the fingers in two static arm postures and under three conditions of electrical stimulation of the arm. The tasks were quantified in terms of maximum MCP torque [MCP flexion (MCP_flex) or MCP extension (MCP_ext)] and activity …

Patterns Of Hypermetria And Terminal Cocontraction During Point-To-Point Movements Demonstrate Independent Action Of Trajectory And Postural Controllers, Robert A. Scheidt, Claude Ghez, Supriya Asnani

Biomedical Engineering Faculty Research and Publications

We examined elbow muscle activities and movement kinematics to determine how subjects combine elementary control actions in performing movements with one and two trajectory segments. In reaching, subjects made a rapid elbow flexion to a visual target before stabilizing the limb with either a low or a higher level of elbow flexor/extensor coactivity (CoA), which was cued by target diameter. Cursor diameter provided real-time biofeedback of actual muscle CoA. In reversing, the limb was to reverse direction within the target and return to the origin with minimal CoA. We previously reported that subjects overshoot the goal when attempting a reversal …

Sensing With The Motor Cortex, Nicholas G. Hatsopoulos, Aaron J. Suminski

Biomedical Engineering Faculty Research and Publications

The primary motor cortex is a critical node in the network of brain regions responsible for voluntary motor behavior. It has been less appreciated, however, that the motor cortex exhibits sensory responses in a variety of modalities including vision and somatosensation. We review current work that emphasizes the heterogeneity in sensorimotor responses in the motor cortex and focus on its implications for cortical control of movement as well as for brain-machine interface development.

Ranolazine Reduces Ca2+ Overload And Oxidative Stress And Improves Mitochondrial Integrity To Protect Against Ischemia Reperfusion Injury In Isolated Hearts, Mohammed Aldakkak, Amadou K.S. Camara, James S. Heisner, Meiying Yang, David F. Stowe

Biomedical Engineering Faculty Research and Publications

Ranolazine is a clinically approved drug for treating cardiac ventricular dysrhythmias and angina. Its mechanism(s) of protection is not clearly understood but evidence points to blocking the late Na⁺ current that arises during ischemia, blocking mitochondrial complex I activity, or modulating mitochondrial metabolism. Here we tested the effect of ranolazine treatment before ischemia at the mitochondrial level in intact isolated hearts and in mitochondria isolated from hearts at different times of reperfusion. Left ventricular (LV) pressure (LVP), coronary flow (CF), and O₂ metabolism were measured in guinea pig isolated hearts perfused with Krebs-Ringer’s solution; mitochondrial (m) O_{2 …}

Bilateral Assessment Of Functional Tasks For Robot-Assisted Therapy Applications, Michelle J. Johnson, Sarah Wang, Ping Bai, Elaine Strachota, Guennady Tchekanov, Jeff Melbye, John Mcguire

Biomedical Engineering Faculty Research and Publications

This article presents a novel evaluation system along with methods to evaluate bilateral coordination of arm function on activities of daily living tasks before and after robot-assisted therapy. An affordable bilateral assessment system (BiAS) consisting of two mini-passive measuring units modeled as three degree of freedom robots is described. The process for evaluating functional tasks using the BiAS is presented and we demonstrate its ability to measure wrist kinematic trajectories. Three metrics, phase difference, movement overlap, and task completion time, are used to evaluate the BiAS system on a bilateral symmetric (bi-drink) and a bilateral asymmetric (bi-pour) functional task. Wrist …

Motion Analysis Of The Upper Extremities During Lofstrand Crutch-Assisted Gait In Children With Orthopaedic Disabilities, Brooke A. Slavens, Neha Bhagchandani, Mei Wang, Peter A. Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background

This paper presents a review of current state-of-the-art dynamic systems for quantifying the kinematics and kinetics of the joints of the upper extremities during Lofstrand crutch-assisted gait. The reviewed systems focus on the rehabilitation of children and adults with myelomeningocele (MM), cerebral palsy (CP), spinal cord injury (SCI), and osteogenesis imperfecta (OI). Forearm crutch systems have evolved from models with single- to multi-sensor hardware systems that can incorporate an increasing number of segments that are in compliance with the standards of the International Society of Biomechanics (ISB).

Methods

The initial system developed by our group was a single, six-axis, …

Upper Extremity Joint Dynamics During Walker Assisted Gait: A Quantitative Approach Towards Rehabilitative Intervention, Katherine A. Konop, Kelly M.B. Strifling, Joseph Krzak, Adam Graf, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background

Many children with spastic diplegic cerebral palsy (CP) use anterior or posterior walkers to aid ambulation. Prolonged use may lead to upper extremity (UE) pathology later in life, including arthritis and joint contractures.

Purpose

This study analyzes the dynamics (kinematics and kinetics) of the shoulder (glenohumeral), elbow, and wrist joints during anterior and posterior walker use. It also examines the dynamic effects of adjusting handle height and grip rotation.

Methods

Ten children with CP underwent motion analysis with upper and lower extremity marker sets and six-degree-of-freedom instrumented walker handles, while using both anterior and posterior walkers. One child underwent …

Analysis Of Push-Off Power During Locomotion In Children With Type 1 Osteogenesis Imperfecta, Joseph Krzak, Adam Graf, Ann Flanagan, Angela Caudill, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background/Purpose

Children with type 1 osteogenesis imperfecta (OI) present with abnormal gait characteristics, including reduced power generation during pushoff. However, the exact biomechanical factors associated with reduced power generation are not clearly understood. The purpose of this study was to investigate the biomechanical factors associated with a reduction in ankle power generation in children with type 1 OI.

Methods

Twenty-four participants with type 1 OI (12.5 ± 3.6 years of age) and 24 typically developing children (12.4 ± 3.7 years of age) were evaluated. Three-dimensional gait analysis, isometric plantar flexion strength using dynamometry, and pedobarography were collected on each participant. …

Current Research And Clinical Applications In Human Motion Analysis, Ken N. Kuo, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Region-Of-Interest Material Decomposition From Truncated Energy-Resolved Ct, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose: Energy-resolved CT using photon-counting detectors has the potential to provide improved material decomposition compared to dual-kVp approaches. However, available photon-counting detectors are susceptible to pulse-pileup artifacts, especially at the periphery of the field of view (FOV) where the object attenuation is low compared to the center of the FOV. Pulse pileup may be avoided by imaging a region-of-interest (ROI) where the dynamic range is expected to be limited. This work investigated performing material decomposition and reconstructing ROI basis images from truncated energy-resolved data.

Methods: A method is proposed to reconstructimages of basis functions primarily contained within the ROI, such …

A Compressed Sensing Algorithm For Sparse-View Pinhole Single Photon Emission Computed Tomography, Paul Arthur Wolf, Emil Y. Sidky, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Single Photon Emission Computed Tomography (SPECT) systems are being developed with multiple cameras and without gantry rotation to provide rapid dynamic acquisitions. However, the resulting data is angularly undersampled, due to the limited number of views. We propose a novel reconstruction algorithm for sparse-view SPECT based on Compressed Sensing (CS) theory. The algorithm models Poisson noise by modifying the Iterative Hard Thresholding algorithm to minimize the Kullback-Leibler (KL) distance by gradient descent. Because the underlying objects of SPECT images are expected to be smooth, a discrete wavelet transform (DWT) using an orthogonal spline wavelet kernel is used as the sparsifying …

A Model For The Evaluation Of Lower Extremity Kinematics With Integrated Multisegmental Foot Motion, Jason T. Long, Mei Wang, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background/Purpose

Current models for assessing lower extremity motion during gait benefit from ease of use in the clinical environment. However, underlying assumptions regarding joint location and distal segment motion limit their effectiveness and accuracy. The aim of this study was to develop a model for lower extremity motion analysis, which integrates functional methods for estimating hip joint center (HJC) location and a multisegmental approach to modeling motion of the foot and ankle. The new model is capable of tracking the motion of six segments (pelvis, bilateral thigh, tibia, hindfoot, forefoot, and hallux) during stance and swing.

Methods

Ten healthy young …

Implications Of Arm Restraint On Lower Extremity Kinetics During Gait, Jason T. Long, John B. Groner, Dan C. Eastwood, Timothy R. Dillingham, Prateek Grover, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background

Literature indicates the importance of the upper extremities in providing stability and propulsion for the body during ambulation. However, the kinetic implications of upper extremity restraint during gait are not as well documented.

Aim

The objective of this study was to examine the effect of arm restraint (unilateral and bilateral) on lower extremity joint kinetics during walking.

Methods

Twenty-three healthy young participants were instrumented for three dimensional motion analysis, and tested in four randomly ordered upper extremity restraint conditions (unrestrained, bilateral restraint, right side restraint, and left side restraint). Temporal spatial parameters and gait/phase-specific lower extremity kinetics and kinematics …

Postoperative Foot And Ankle Kinematics In Rheumatoid Arthritis, Karl Canseco, Carolyne Albert, Jason T. Long, Michael Khazzam, Richard Marks, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Introduction

Rheumatoid arthritis (RA) is a systemic autoimmune disease that can cause weakening and destruction of various joints of the foot and may result in pain and deformity. This clinical presentation can cause eventual loss of function, shoe-wear difficulties, and altered gait patterns.

Purpose

The goal of this prospective study was to quantify changes in temporal-spatial parameters and multisegmental foot and ankle kinematics in a group of patients with RA of the forefoot following surgery.

Methods

Three-dimensional (3-D) motion analysis was conducted preoperatively and postoperatively using a 15-camera Vicon Motion Analysis System (Vicon Motion Systems, Inc.; Lake Forest, CA) on …

Computational Simulations Demonstrate Altered Wall Shear Stress In Aortic Coarctation Patients Previously Treated By Resection With End-To-End Anastomosis, John F. Ladisa, Ronak Jashwant Dholakia, Alberto Figueroa, Irene E. Vignon-Clementel, Frandics P. Chan, Margaret M. Samyn, Joseph Richard Cava, Charles A. Taylor, Jeffrey A. Feinstein

Biomedical Engineering Faculty Research and Publications

Background.  Atherosclerotic plaque in the descending thoracic aorta (dAo) is related to altered wall shear stress (WSS) for normal patients. Resection with end-to-end anastomosis (RWEA) is the gold standard for coarctation of the aorta (CoA) repair, but may lead to altered WSS indices that contribute to morbidity.

Methods.  Computational fluid dynamics (CFD) models were created from imaging and blood pressure data for control subjects and age- and gender-matched CoA patients treated by RWEA (four males, two females, 15 ± 8 years). CFD analysis incorporated downstream vascular resistance and compliance to generate blood flow velocity, time-averaged WSS (TAWSS), and oscillatory shear …

Computational Simulations For Aortic Coarctation: Representative Results From A Sampling Of Patients, John F. Ladisa, Alberto Figueroa, Irene E. Vignon-Clementel, Hyun Jin Kim, Nan Xiao, Laura M. Ellwein, Frandics P. Chan, Jeffrey A. Feinstein, Charles A. Taylor

Biomedical Engineering Faculty Research and Publications

Treatments for coarctation of the aorta (CoA) can alleviate blood pressure (BP) gradients(D), but long-term morbidity still exists that can be explained by altered indices of hemodynamics and biomechanics. We introduce a technique to increase our understanding of these indices for CoA under resting and nonresting conditions, quantify their contribution to morbidity, and evaluate treatment options. Patient-specific computational fluid dynamics (CFD) models were created from imaging and BP data for one normal and four CoA patients (moderate native CoA: D12 mmHg, severe native CoA: D25 mmHg and postoperative end-to-end and end-to-side patients: D0 mmHg). Simulations incorporated vessel deformation, downstream vascular …

Effects Of Wrist Tendon Vibration On Arm Tracking In People Poststroke, Megan O. Conrad, Robert A. Scheidt, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

The goal of this study was to evaluate the influence of wrist tendon vibration on a multijoint elbow/shoulder tracking task. We hypothesized that tendon vibration applied at the wrist musculature would improve upper arm tracking performance in chronic stroke survivors through increased, Ia-afferent feedback to the central nervous system (CNS). To test this hypothesis, 10 chronic stroke and 5 neurologically intact subjects grasped the handle of a planar robot as they tracked a target through a horizontal figure-8 pattern. A total of 36 trials were completed by each subject. During the middle trials, 70-Hz tendon vibration was applied at the …

Spatial And Temporal Variation Of Rod Photoreceptor Reflectance In The Human Retina, Robert F. Cooper, Adam M. Dubis, Ashavini M. Pavaskar, Jungtae Rha, Alfredo Dubra, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Using adaptive optics imaging tools to image the living retina, numerous investigators have reported temporal fluctuation in the reflectivity of individual cone photoreceptors. In addition, there is cone-to-cone (spatial) variation in reflectivity. As it has only recently become possible to image the complete rod photoreceptor mosaic in the living human retina, we sought to characterize the reflectivity of individual rods and compare their behavior to that of foveal/parafoveal cones. Across two subjects, we were able to successfully track the reflectance behavior of 1,690 rods and 1,980 cones over 12 hours. Rod and cone photoreceptors showed similar regional and temporal variability …

Carotid Plaque Regression Following 6-Month Statin Therapy Assessed By 3t Cardiovascular Magnetic Resonance: Comparison With Ultrasound Intima Media Thickness, Raymond Q. Migrino, Mark Bowers, Leanne Harmann, Robert W. Prost, John F. Ladisa

Biomedical Engineering Faculty Research and Publications

Background

Cardiovascular magnetic resonance (CMR) allows volumetric carotid plaque measurement that has advantage over 2-dimensional ultrasound (US) intima-media thickness (IMT) in evaluating treatment response. We tested the hypothesis that 6-month statin treatment in patients with carotid plaque will lead to plaque regression when measured by 3 Tesla CMR but not by IMT.

Methods

Twenty-six subjects (67 ± 2 years, 7 females) with known carotid plaque (> 1.1 mm) and coronary or cerebrovascular atherosclerotic disease underwent 3T CMR (T1, T2, proton density and time of flight sequences) and US at baseline and following 6 months of statin therapy (6 had initiation, …

Global Flow Impacts Time-To-Passage Judgments Based On Local Motion Cues, Scott A. Beardsley, Elif M. Sikoglu, Heiko Hecht, Lucia M. Vaina

Biomedical Engineering Faculty Research and Publications

We assessed the effect of the coherence of optic flow on time-to-passage judgments in order to investigate the strategies that observers use when local expansion information is reduced or lacking. In the standard display, we presented a cloud of dots whose image expanded consistent with constant observer motion. The dots themselves, however, did not expand and were thus devoid of object expansion cues. Only the separations between the dots expanded. Subjects had to judge which of two colored target dots, presented at different simulated depths and lateral displacements would pass them first. Image velocities of the target dots were chosen …

Differential Responses Of Targeted Lung Redox Enzymes To Rat Exposure To 60 Or 85% Oxygen, Zhuohui Gan, David L. Roerig, Anne V. Clough, Said H. Audi

Biomedical Engineering Faculty Research and Publications

Rat exposure to 60% O₂ (hyper-60) or 85% O₂ (hyper-85) for 7 days confers susceptibility or tolerance, respectively, of the otherwise lethal effects of exposure to 100% O₂. The objective of this study was to determine whether activities of the antioxidant cytosolic enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1) and mitochondrial complex III are differentially altered in hyper-60 and hyper-85 lungs. Duroquinone (DQ), an NQO1 substrate, or its hydroquinone (DQH₂), a complex III substrate, was infused into the arterial inflow of isolated, perfused lungs, and the venous efflux rates of DQH₂ and DQ were measured. …

Noninvasive Imaging Of The Human Rod Photoreceptor Mosaic Using A Confocal Adaptive Optics Scanning Ophthalmoscope, Alfredo Dubra, Yusufu N. Sulai, Jennifer L. Norris, Robert F. Cooper, Adam M. Dubis, David R. Williams, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

The rod photoreceptors are implicated in a number of devastating retinal diseases. However, routine imaging of these cells has remained elusive, even with the advent of adaptive optics imaging. Here, we present the first in vivo images of the contiguous rod photoreceptor mosaic in nine healthy human subjects. The images were collected with three different confocal adaptive optics scanning ophthalmoscopes at two different institutions, using 680 and 775 nm superluminescent diodes for illumination. Estimates of photoreceptor density and rod:cone ratios in the 5°–15° retinal eccentricity range are consistent with histological findings, confirming our ability to resolve the rod mosaic by …

Effect Of Ankle Orientation On Heel Loading And Knee Stability For Post-Stroke Individuals Wearing Ankle-Foot Orthoses, M. Barbara Silver-Thorn

Biomedical Engineering Faculty Research and Publications

Background: Those who experience lower extremity weakness or paralysis following a stroke often exhibit gait deviations caused by the inability to completely lift their foot during swing. An ankle-foot orthosis (AFO) is commonly prescribed for individuals post stroke with this mobility impairment.

Study design: Randomized controlled trial.

Objectives: To determine whether significant differences could be observed in post-stroke individuals ambulating with an experimental AFO set at three different ankle orientations.

Methods: Gait analysis was conducted for eight post-stroke individuals ambulating with an experimental AFO set in three different randomly selected ankle orientations: 5° dorsiflexion, 5° plantarflexion, and neutral alignment. Temporospatial …

Salen Mn Complexes Mitigate Radiation Injury In Normal Tissues, Rosalind A. Rosenthal, Brian Fish, Richard P. Hill, Karl D. Huffman, Zelmira Lazarova, Javed Mahmood, Meetha Medhora, Robert C. Molthen, John E. Moulder, Stephen T. Sonis, Philip J. Tofilon, Susan R. Doctrow

Biomedical Engineering Faculty Research and Publications

Salen Mn complexes, including EUK-134, EUK-189 and a newer cyclized analog EUK-207, are synthetic SOD/catalase mimetics that have beneficial effects in many models of oxidative stress. As oxidative stress is implicated in some forms of delayed radiation injury, we are investigating whether these compounds can mitigate injury to normal tissues caused by ionizing radiation. This review describes some of this research, focusing on several tissues of therapeutic interest, namely kidney, lung, skin, and oral mucosa. These studies have demonstrated suppression of delayed radiation injury in animals treated with EUK-189 and/or EUK-207. While an antioxidant mechanism of action is postulated, it …

A Rapid And Computationally Inexpensive Method To Virtually Implant Current And Next-Generation Stents Into Subject-Specific Computational Fluid Dynamics Models, Timothy J. Gundert, Shawn C. Shadden, Andrew R. Williams, Bon-Kwon Koo, Jeffrey A. Feinstein, John F. Ladisa

Biomedical Engineering Faculty Research and Publications

Computational modeling is often used to quantify hemodynamic alterations induced by stenting, but frequently uses simplified device or vascular representations. Based on a series of Boolean operations, we developed an efficient and robust method for assessing the influence of current and next-generation stents on local hemodynamics and vascular biomechanics quantified by computational fluid dynamics. Stent designs were parameterized to allow easy control over design features including the number, width and circumferential or longitudinal spacing of struts, as well as the implantation diameter and overall length. The approach allowed stents to be automatically regenerated for rapid analysis of the contribution of …

Mitochondrial Approaches To Protect Against Cardiac Ischemia And Reperfusion Injury, Amadou K.S. Camara, Martin Bienengraeber, David F. Stowe

Biomedical Engineering Faculty Research and Publications

The mitochondrion is a vital component in cellular energy metabolism and intracellular signaling processes. Mitochondria are involved in a myriad of complex signaling cascades regulating cell death vs. survival. Importantly, mitochondrial dysfunction and the resulting oxidative and nitrosative stress are central in the pathogenesis of numerous human maladies including cardiovascular diseases, neurodegenerative diseases, diabetes, and retinal diseases, many of which are related. This review will examine the emerging understanding of the role of mitochondria in the etiology and progression of cardiovascular diseases and will explore potential therapeutic benefits of targeting the organelle in attenuating the disease process. Indeed, recent advances …

Micro-Ct Characterization Of Human Trabecular Bone In Osteogenesis Imperfecta, John Jameson, Carolyne Albert, Peter Smith, Robert C. Molthen, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Osteogenesis imperfecta (OI) is a genetic syndrome affecting collagen synthesis and assembly. Its symptoms vary widely but commonly include bone fragility, reduced stature, and bone deformity. Because of the small size and paucity of human specimens, there is a lack of biomechanical data for OI bone. Most literature has focused on histomorphometric analyses, which rely on assumptions to extrapolate 3-D properties. In this study, a micro-computed tomography (μCT) system was used to directly measure structural and mineral properties in pediatric OI bone collected during routine surgical procedures. Surface renderings suggested a poorly organized, plate-like orientation. Patients with a history of …