Biomedical Engineering and Bioengineering Commons^™

The Reliability Of Parafoveal Cone Density Measurements, Benjamin S. Liu, Sergey Tarima, Alexis D. Visotcky, Alex Pechauer, Robert F. Cooper, Leah Landsem, Melissa A. Wilk, Pooja Godara, Vikram Makhijani, Yusufu N. Sulai, Najia Syed, Galen Yasumura, Anupam K. Garg, Mark E. Pennesi, Brandon J. Lujan, Alfredo Dubra, Jacque L. Duncan, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Background Adaptive optics scanning light ophthalmoscopy (AOSLO) enables direct visualisation of the cone mosaic, with metrics such as cone density and cell spacing used to assess the integrity or health of the mosaic. Here we examined the interobserver and inter-instrument reliability of cone density measurements.

Methods For the interobserver reliability study, 30 subjects with no vision-limiting pathology were imaged. Three image sequences were acquired at a single parafoveal location and aligned to ensure that the three images were from the same retinal location. Ten observers used a semiautomated algorithm to identify the cones in each image, and this was repeated …

Relationship Between Foveal Cone Specialization And Pit Morphology In Albinism, Melissa A. Wilk, John T. Mcallister, Robert F. Cooper, Adam M. Dubis, Teresa N. Patitucci, Phyllis Summerfelt, Jennifer L. Anderson, Deborah M. Costakos, Thomas B. Connor Jr., William J. Wirostko, Pei-Wen Chiang, Alfredo Dubra, Christine A. Curcio, Murray H. Briliant, C. Gail Summers, Joseph Carroll, Jennifer L. Anderson

Biomedical Engineering Faculty Research and Publications

Purpose. Albinism is associated with disrupted foveal development, though intersubject variability is becoming appreciated. We sought to quantify this variability, and examine the relationship between foveal cone specialization and pit morphology in patients with a clinical diagnosis of albinism.

Methods. We recruited 32 subjects with a clinical diagnosis of albinism. DNA was obtained from 25 subjects, and known albinism genes were analyzed for mutations. Relative inner and outer segment (IS and OS) lengthening (fovea-to-perifovea ratio) was determined from manually segmented spectral domain-optical coherence tomography (SD-OCT) B-scans. Foveal pit morphology was quantified for eight subjects from macular SD-OCT volumes. Ten subjects …

Microscopic Inner Retinal Hyper-Reflective Phenotypes In Retinal And Neurologic Disease, Drew Scoles, Brian P. Higgins, Robert F. Cooper, Adam M. Dubis, Phyllis Summerfelt, David V. Weinberg, Judy E. Kim, Kimberly E. Stepien, Joseph Carroll, Alfredo Dubra

Biomedical Engineering Faculty Research and Publications

Purpose.

We surveyed inner retinal microscopic features in retinal and neurologic disease using a reflectance confocal adaptive optics scanning light ophthalmoscope (AOSLO).

Methods.

Inner retinal images from 101 subjects affected by one of 38 retinal or neurologic conditions and 11 subjects with no known eye disease were examined for the presence of hyper-reflective features other than vasculature, retinal nerve fiber layer, and foveal pit reflex. The hyper-reflective features in the AOSLO images were grouped based on size, location, and subjective texture. Clinical imaging, including optical coherence tomography (OCT), scanning laser ophthalmoscopy, and fundus photography was analyzed for comparison.

Results.

Seven …

Effect Of Lowest Instrumented Vertebra On Trunk Mobility In Patients With Adolescent Idiopathic Scoliosis Undergoing A Posterior Spinal Fusion, Ubong I. Udoekwere, Joseph Krzak, Adam Graf, Sahar Hassani, Sergey Tarima, Mary Riordan, Peter F. Sturm, Kim W. Hammerberg, Purnendu Gupta, Alireza K. Anissipour, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Study Design

Prospective.

Objectives

The goal of this study was to evaluate the effect of posterior spinal fusion surgery terminating at different lowest instrumented vertebrae (LIV) on trunk mobility in individuals with adolescent idiopathic scoliosis (AIS).

Summary of Background Data

Posterior spinal fusion with instrumentation is the standard surgical technique employed in AIS for correcting spine deformities with Cobb angles exceeding 50°. Surgical correction of curve deformity reduces trunk mobility and range of motion. However, conflicting findings from previous studies investigating the impact of different LIV levels on the reduction in trunk mobility after surgery have been reported.

Methods

The …

Measuring Tumor Cycling Hypoxia And Angiogenesis Using A Side-Firing Fiber Optic Probe, Bing Yu, Amy Shah, Bingqing Wang, Narasimhan Rajaram, Quanli Wang, Nirmala Ramanujam, Gregory M. Palmer, Mark W. Dewhirst

Biomedical Engineering Faculty Research and Publications

Hypoxia and angiogenesis can significantly influence the efficacy of cancer therapy and the behavior of surviving tumor cells. There is a growing demand for technologies to measure tumor hypoxia and angiogenesis temporally in vivo to enable advances in drug development and optimization. This paper reports the use of frequency-domain photon migration with a side-firing probe to quantify tumor oxygenation and hemoglobin concentrations in nude rats bearing human head/neck tumors administered with carbogen gas, cycling hypoxic gas or just room air. Significant increase (with carbogen gas breathing) or decrease (with hypoxic gas breathing) in tumor oxygenation was observed. The trend in …

Looking For Your Next Disruptive Technology? Try Student Competitions, Jay R. Goldberg, Phil Weilerstein

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Learning Redundant Motor Tasks With And Without Overlapping Dimensions: Facilitation And Interference Effects, Rajiv Ranganathan, Jon A. Wieser, Kristine M. Mosier, Ferdinando A. Mussa-Ivaldi, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

Prior learning of a motor skill creates motor memories that can facilitate or interfere with learning of new, but related, motor skills. One hypothesis of motor learning posits that for a sensorimotor task with redundant degrees of freedom, the nervous system learns the geometric structure of the task and improves performance by selectively operating within that task space. We tested this hypothesis by examining if transfer of learning between two tasks depends on shared dimensionality between their respective task spaces. Human participants wore a data glove and learned to manipulate a computer cursor by moving their fingers. Separate groups of …

In Vivo Imaging Of Human Cone Photoreceptor Inner Segments, Drew Scoles, Yusufu N. Sulai, Christopher S. Langlo, Gerald A. Fishman, Christine A. Curcio, Joseph Carroll, Alfredo Dubra

Biomedical Engineering Faculty Research and Publications

Purpose.

An often overlooked prerequisite to cone photoreceptor gene therapy development is residual photoreceptor structure that can be rescued. While advances in adaptive optics (AO) retinal imaging have recently enabled direct visualization of individual cone and rod photoreceptors in the living human retina, these techniques largely detect strongly directionally-backscattered (waveguided) light from normal intact photoreceptors. This represents a major limitation in using existing AO imaging to quantify structure of remnant cones in degenerating retina.

Methods.

Photoreceptor inner segment structure was assessed with a novel AO scanning light ophthalmoscopy (AOSLO) differential phase technique, that we termed nonconfocal split-detector, in two healthy …

Electroencephalogram Coherence In Children With And Without Autism Spectrum Disorders: Decreased Interhemispheric Connectivity In Autism, Audrey Meyer Carson, Nicole M.G. Salowitz, Robert A. Scheidt, Bridget K. Dolan, Amy V. Van Hecke

Biomedical Engineering Faculty Research and Publications

Electroencephalogram coherence was measured in children with autism spectrum disorders (ASD) and control children at baseline and while watching videos of a familiar and unfamiliar person reading a story. Coherence was measured between the left and right hemispheres of the frontal, parietal, and temporal-parietal lobes (interhemispheric) and between the frontal and parietal lobes in each hemisphere (intrahemispheric). A data-reduction technique was employed to identify the frequency (alpha) that yielded significant differences in video conditions. Children with ASD displayed reduced coherence at the alpha frequency between the left and right temporal-parietal lobes in all conditions and reduced coherence at the alpha …

Faculty Internships For Capstone Design Instructors: Maintaining An Up-To-Date Capstone Design Course, Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Robotic Resistance/Assistance Training Improves Locomotor Function In Individuals Poststroke: A Randomized Controlled Study, Ming Wu, Jill M. Landry, Janis Kim, Brian D. Schmit, Sheng-Che Yen, Jillian Macdonald

Biomedical Engineering Faculty Research and Publications

Objective

To determine whether providing a controlled resistance versus assistance to the paretic leg at the ankle during treadmill training will improve walking function in individuals poststroke.

Design

Repeated assessment of the same patients with parallel design and randomized controlled study between 2 groups.

Setting

Research units of rehabilitation hospitals.

Participants

Patients (N=30) with chronic stroke.

Intervention

Subjects were stratified based on self-selected walking speed and were randomly assigned to the resistance or assistance training group. For the resistance group, a controlled resistance load was applied to the paretic leg at the ankle to resist leg swing during treadmill walking. …

Feedback Regulation Of Limb Position Characterized Using Fmri, Aaron J. Suminski, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Quantification Of Local Hemodynamic Alterations Caused By Virtual Implantation Of Three Commercially Available Stents For The Treatment Of Aortic Coarctation, Sung Kwon, Jeffrey A. Feinstein, Ronak Jashwant Dholakia, John F. Ladisa

Biomedical Engineering Faculty Research and Publications

Patients with coarctation of the aorta (CoA) are prone to morbidity including atherosclerotic plaque that has been shown to correlate with altered wall shear stress (WSS) in the descending thoracic aorta (dAo). We created the first patient-specific computational fluid dynamics (CFD) model of a CoA patient treated by Palmaz stenting to date, and compared resulting WSS distributions to those from virtual implantation of Genesis XD and modified NuMED CP stents, also commonly used for CoA. CFD models were created from magnetic resonance imaging, fluoroscopy and blood pressure data. Simulations incorporated vessel deformation, downstream vascular resistance and compliance to match measured …

Long-Term Results Of Comprehensive Clubfoot Release Versus The Ponseti Method: Which Is Better?, Peter A. Smith, Ken N. Kuo, Adam Graf, Joseph Krzak, Ann Flanagan, Sahar Hassani, Angela Caudill, Frederick Dietz, Jose Morcuende, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background

Clubfoot can be treated nonoperatively, most commonly using a Ponseti approach, or surgically, most often with a comprehensive clubfoot release. Little is known about how these approaches compare with one another at longer term, or how patients treated with these approaches differ in terms of foot function, foot biomechanics, or quality-of-life from individuals who did not have clubfoot as a child.

Questions/purposes

We compared (1) focused physical and radiographic examinations, (2) gait analysis, and (3) quality-of-life measures at long-term followup between groups of adult patients with clubfoot treated either with the Ponseti method of nonsurgical management or a comprehensive …

A Robotic Test Of Proprioception Within The Hemiparetic Arm Post-Stroke, Lucia Simo, Lior Botzer, Claude Ghez, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

Background: Proprioception plays important roles in planning and control of limb posture and movement. The impact of proprioceptive deficits on motor function post-stroke has been difficult to elucidate due to limitations in current tests of arm proprioception. Common clinical tests only provide ordinal assessment of proprioceptive integrity (eg. intact, impaired or absent). We introduce a standardized, quantitative method for evaluating proprioception within the arm on a continuous, ratio scale. We demonstrate the approach, which is based on signal detection theory of sensory psychophysics, in two tasks used to characterize motor function after stroke.

Methods: Hemiparetic stroke survivors and neurologically intact …

Classification Of Human Retinal Microaneurysms Using Adaptive Optics Scanning Light Ophthalmoscope Fluorescein Angiography, Michael Dubow, Alexander Pinhas, Nishit Shah, Robert F. Cooper, Alexander Gan, Ronald C. Gentile, Vernon Hendrix, Yusufu N. Sulai, Joseph Carroll, Toco Y.P. Chui, Joseph B. Walsh, Rishard Weitz, Alfredo Dubra, Richard B. Rosen

Biomedical Engineering Faculty Research and Publications

Purpose.

Microaneurysms (MAs) are considered a hallmark of retinal vascular disease, yet what little is known about them is mostly based upon histology, not clinical observation. Here, we use the recently developed adaptive optics scanning light ophthalmoscope (AOSLO) fluorescein angiography (FA) to image human MAs in vivo and to expand on previously described MA morphologic classification schemes.

Methods.

Patients with vascular retinopathies (diabetic, hypertensive, and branch and central retinal vein occlusion) were imaged with reflectance AOSLO and AOSLO FA. Ninety-three MAs, from 14 eyes, were imaged and classified according to appearance into six morphologic groups: focal bulge, saccular, fusiform, mixed, …

Comparison Of Adaptive Optics Scanning Light Ophthalmoscopic Fluorescein Angiography And Offset Pinhole Imaging, Toco Y.P. Chui, Michael Dubow, Alexander Pinhas, Nishit Shah, Alexander Gan, Rishard Weitz, Yusufu N. Sulai, Alfredo Dubra, Richard B. Rosen

Biomedical Engineering Faculty Research and Publications

Recent advances to the adaptive optics scanning light ophthalmoscope (AOSLO) have enabled finer in vivo assessment of the human retinal microvasculature. AOSLO confocal reflectance imaging has been coupled with oral fluorescein angiography (FA), enabling simultaneous acquisition of structural and perfusion images. AOSLO offset pinhole (OP) imaging combined with motion contrast post-processing techniques, are able to create a similar set of structural and perfusion images without the use of exogenous contrast agent. In this study, we evaluate the similarities and differences of the structural and perfusion images obtained by either method, in healthy control subjects and in patients with retinal vasculopathy …

Isoflurane Modulates Cardiac Mitochondrial Bioenergetics By Selectively Attenuating Respiratory Complexes, Bhawana Agarwal, Ranjan K. Dash, David F. Stowe, Zeljko J. Bosnjak, Amadou K.S. Camara

Biomedical Engineering Faculty Research and Publications

Mitochondrial dysfunction contributes to cardiac ischemia–reperfusion (IR) injury but volatile anesthetics (VA) may alter mitochondrial function to trigger cardioprotection. We hypothesized that the VA isoflurane (ISO) mediates cardioprotection in part by altering the function of several respiratory and transport proteins involved in oxidative phosphorylation (OxPhos). To test this we used fluorescence spectrophotometry to measure the effects of ISO (0, 0.5, 1, 2 mM) on the time-course of interlinked mitochondrial bioenergetic variables during states 2, 3 and 4 respiration in the presence of either complex I substrate K⁺-pyruvate/malate (PM) or complex II substrate K⁺-succinate (SUC) at physiological …

Diffuse Reflectance Spectroscopy Of Epithelial Tissue With A Smart Fiber-Optic Probe, Bing Yu, Amy Shah, Vivek K. Nagarajan, Daron G. Ferris

Biomedical Engineering Faculty Research and Publications

Diffuse reflectance spectroscopy (DRS) with a fiber-optic probe can noninvasively quantify the optical properties of epithelial tissues and has shown the potential as a cost-effective, fast and sensitive tool for diagnosis of early precancerous changes in the cervix and oral cavity. However, current DRS systems are susceptible to several sources of systematic and random errors, such as uncontrolled probe-to-tissue pressure and lack of a real-time calibration that can significantly impair the measurement accuracy, reliability and validity of this technology as well as its clinical utility. In addition, such systems use bulky, high power and expensive optical components which impede their …

A Lensing Effect Of Inner Retinal Cysts On Images Of The Photoreceptor Mosaic, Christopher S. Langlo, John A. Flatter, Alfredo Dubra, William J. Wirostko, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Biomechanical Model For Evaluation Of Pediatric Upper Extremity Joint Dynamics During Wheelchair Mobility, Alyssa J. Schnorenberg, Brooke A. Slavens, Mei Wang, Lawrence Vogel, Peter Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Pediatric manual wheelchair users (MWU) require high joint demands on their upper extremity (UE) during wheelchair mobility, leading them to be at risk of developing pain and pathology. Studies have examined UE biomechanics during wheelchair mobility in the adult population; however, current methods for evaluating UE joint dynamics of pediatric MWU are limited. An inverse dynamics model is proposed to characterize three-dimensional UE joint kinematics and kinetics during pediatric wheelchair mobility using a SmartWheel instrumented handrim system. The bilateral model comprises thorax, clavicle, scapula, upper arm, forearm, and hand segments and includes the sternoclavicular, acromioclavicular, glenohumeral, elbow and wrist joints. …

Diffusion Tensor Imaging Of The Spinal Cord: Insights From Animal And Human Studies, Aditya Vedantam, Michael B. Jirjis, Brian D. Schmit, Marjorie C. Wang, John L. Ulmer, Shekar N. Kurpad

Biomedical Engineering Faculty Research and Publications

Diffusion tensor imaging (DTI) provides a measure of the directional diffusion of water molecules in tissues. The measurement of DTI indexes within the spinal cord provides a quantitative assessment of neural damage in various spinal cord pathologies. DTI studies in animal models of spinal cord injury indicate that DTI is a reliable imaging technique with important histological and functional correlates. These studies demonstrate that DTI is a noninvasive marker of microstructural change within the spinal cord. In human studies, spinal cord DTI shows definite changes in subjects with acute and chronic spinal cord injury, as well as cervical spondylotic myelopathy. …

Benefits Of Industry Involvement In Multidisciplinary Capstone Design Courses, Jay R. Goldberg, Vikram Cariapa, George Corliss, Kate Kaiser

Biomedical Engineering Faculty Research and Publications

Opportunities for industry involvement in capstone design courses go beyond industry sponsorship of capstone design projects. Representatives from industry can serve as guest lecturers, curriculum advisors, and design project sponsors and team mentors. Since 2000, industry participation has been a core part of the capstone design course at Marquette University. Practicing engineers provide a relevant, practical real-world perspective of their topic, reinforcing its importance to professional engineering practice. Students and faculty benefit from the up-to-date treatment of the topic provided by guest speakers from industry who have expertise in the topic and are willing to share their experiences with students. …

Age-Related Differentiation Of Sensorimotor Control Strategies During Pursuit And Compensatory Tracking, Megan L. Heenan, Robert A. Scheidt, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

Motor control deficits during aging have been well-documented. Various causes of neuromotor decline, including both peripheral and central neurological deficits, have been hypothesized. Here, we use a model of closed-loop sensorimotor control to examine the functional causes of motor control deficits during aging. We recruited 14 subjects aged 19-61 years old to participate in a study in which they performed single-joint compensatory and pursuit tracking tasks with their dominant hand. We found that visual response delay and visual noise increased with age, while reliance on visual feedback, especially during compensatory tracking decreased. Increases in visual noise were also positively correlated …

Submovements During Reaching Movements After Stroke, Lucia S. Simo, Davide Piovesan, Jozsef Laczko, Claude Ghez, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

Neurological deficits after cerebrovascular accidents very frequently disrupt the kinematics of voluntary movements with the consequent impact in daily life activities. Robotic methodologies enable the quantitative characterization of specific control deficits needed to understand the basis of functional impairments and to design effective rehabilitation therapies. In a group of right handed chronic stroke survivors (SS) with right side hemiparesis, intact proprioception, and differing levels of motor impairment, we used a robotic manipulandum to study right arm function during discrete point-to-point reaching movements and reciprocal out-and-back movements to visual targets. We compared these movements with those of neurologically intact individuals (NI). …

Simultaneous Robotic Manipulation And Functional Magnetic Resonance Imaging: Feasibility In Children With Autism Spectrum Disorders, Nicole M.G. Salowitz, Bridget Dolan, Rheanna Remmel, Amy V. Van Hecke, Kristine M. Mosier, Lucia Simo, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

An unanswered question concerning the neural basis of autism spectrum disorders (ASD) is how sensorimotor deficits in individuals with ASD are related to abnormalities of brain function. We previously described a robotic joystick and video game system that allows us to record functional magnetic resonance images (FMRI) while adult humans make goal-directed wrist motions. We anticipated several challenges in extending this approach to studying goal-directed behaviors in children with ASD and in typically developing (TYP) children. In particular we were concerned that children with autism may express increased levels of anxiety as compared to typically developing children due to the …

Simultaneous Robotic Manipulation And Functional Magnetic Resonance Imaging: Feasibility In Children With Autism Spectrum Disorders, Nicole Marie Gregor Salowitz, Bridget K. Dolan, Rheanna Remmel, Amy V. Van Hecke, Kristine M. Mosier, Lucia S. Simo, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

An unanswered question concerning the neural basis of autism spectrum disorders (ASD) is how sensorimotor deficits in individuals with ASD are related to abnormalities of brain function. We previously described a robotic joystick and video game system that allows us to record functional magnetic resonance images (FMRI) while adult humans make goal- directed wrist motions. We anticipated several challenges in extending this approach to studying goal-directed behaviors in children with ASD and in typically developing (TYP) children. In particular we were concerned that children with autism may express increased levels of anxiety as compared to typically developing children due to …

Characterization Of A Human Powered Nebulizer Compressor For Resource Poor Settings, Christopher J. Hallberg, Mary Therese Lysaught, Christopher E. Zmudka, William K. Kopesky, Lars E. Olson

Biomedical Engineering Faculty Research and Publications

Background

Respiratory disease accounts for three of the ten leading causes of death worldwide. Many of these diseases can be treated and diagnosed using a nebulizer. Nebulizers can also be used to safely and efficiently deliver vaccines. Unfortunately, commercially available nebulizers are not designed for use in regions of the world where lung disease is most prevalent: they are electricity-dependent, cost-prohibitive, and not built to be reliable in harsh operating conditions or under frequent use.

To overcome these limitations, the Human Powered Nebulizer compressor (HPN) was developed. The HPN does not require electricity; instead airflow is generated manually through a …

Evaluation Of Upper Extremity Movement Characteristics During Standardized Pediatric Functional Assessment With A Kinect®-Based Markerless Motion Analysis System, Jacob R. Rammer, Joseph J. Krzak, Susan A. Riedel, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

A recently developed and evaluated upper extremity (UE) markerless motion analysis system based on the Microsoft® Kinect® has potential for improving functional assessment of patients with hemiplegic cerebral palsy. 12 typically-developing adolescents ages 12-17 were evaluated using both the Kinect-based system and the Shriners Hospitals for Children Upper Extremity Evaluation (SHUEE), a validated measure of UE motion. The study established population means of UE kinematic parameters for each activity. Statistical correlation analysis was used to identify key kinematic metrics used to develop automatic scoring algorithms. The Kinect motion analysis platform is technically sound and can be applied to standardized task-based …

Virtual Capstone Design Teams: Preparing For Global Innovation (Conference Proceeding), Jay R. Goldberg, Susannah Howe

Biomedical Engineering Faculty Research and Publications

Global innovation requires collaboration between groups of people located in different parts of the world, and is a growing trend in industry. Virtual teams are often used to manage new product development projects. These teams are similar to traditional teams but are geographically separated and rely heavily on virtual methods of communication (email, Skype, teleconferencing, etc.) instead of regular face-to-face meetings. Experience working as a member of a virtual capstone design team can help prepare students for this growing trend. To begin preparing students for work on virtual teams in industry, we co-advised two virtual capstone design projects with students …