Biomedical Engineering and Bioengineering Commons^™

Remapping Hand Movements In A Novel Geometrical Environment, Kristine M. Mosier, Robert A. Scheidt, Santiago Acosta, Ferdinando A. Mussa-Ivaldi

Biomedical Engineering Faculty Research and Publications

The issue of how the Euclidean properties of space are represented in the nervous system is a main focus in the study of visual perception, but is equally relevant to motor learning. The goal of our experiments was to investigate how the properties of space guide the remapping of motor coordination. Subjects wore an instrumented data glove that recorded the finger motions. Signals generated by the glove operated a remotely controlled endpoint: a cursor on a computer monitor. The subjects were instructed to execute movements of this endpoint with controlled motions of the fingers. This required inverting a highly redundant …

Effect Of Chronic Hyperoxic Exposure On Duroquinone Reduction In Adult Rat Lungs, Said H. Audi, Robert D. Bongard, Gary S. Krenz, David A. Rickaby, Steven Thomas Haworth, Jessica Eisenhauer, David L. Roerig, Marilyn P. Merker

Biomedical Engineering Faculty Research and Publications

NAD(P)H:quinone oxidoreductase 1 (NQO1) plays a dominant role in the reduction of the quinone compound 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone, DQ) to durohydroquinone (DQH₂) on passage through the rat lung. Exposure of adult rats to 85% O₂ for ≥7 days stimulates adaptation to the otherwise lethal effects of >95% O₂. The objective of this study was to examine whether exposure of adult rats to hyperoxia affected lung NQO1 activity as measured by the rate of DQ reduction on passage through the lung. We measured DQH₂ appearance in the venous effluent during DQ infusion at different concentrations into …

A Three-Dimensional Reconstruction Algorithm For An Inverse-Geometry Volumetric Ct System, Taly Gilat Schmidt, Rebecca Fahrig, Norbert J. Pelc

Biomedical Engineering Faculty Research and Publications

An inverse-geometry volumetric computed tomography (IGCT) system has been proposed capable of rapidly acquiring sufficient data to reconstruct a thick volume in one circular scan. The system uses a large-area scanned source opposite a smaller detector. The source and detector have the same extent in the axial, or slice, direction, thus providing sufficient volumetric sampling and avoiding cone-beam artifacts. This paper describes a reconstruction algorithm for the IGCT system. The algorithm first rebins the acquired data into two-dimensional (2D) parallel-ray projections at multiple tilt and azimuthal angles, followed by a 3D filtered backprojection. The rebinning step is performed by gridding …

Axial Stent Strut Angle Influences Wall Shear Stress After Stent Implantation: Analysis Using 3d Computational Fluid Dynamics Models Of Stent Foreshortening, John F. Ladisa, Lars E. Olson, Douglas Anthony Hettrick, David C. Warltier, Judy R. Kersten, Paul S. Pagel

Biomedical Engineering Faculty Research and Publications

Introduction

The success of vascular stents in the restoration of blood flow is limited by restenosis. Recent data generated from computational fluid dynamics (CFD) models suggest that the vascular geometry created by an implanted stent causes local alterations in wall shear stress (WSS) that are associated with neointimal hyperplasia (NH). Foreshortening is a potential limitation of stent design that may affect stent performance and the rate of restenosis. The angle created between axially aligned stent struts and the principal direction of blood flow varies with the degree to which the stent foreshortens after implantation.

Methods

In the current investigation, we …

Microfocal X-Ray Computed Tomography Post-Processing Operations For Optimizing Reconstruction Volumes Of Stented Arteries During 3d Computational Fluid Dynamics Modeling, John F. Ladisa, Lars E. Olson, Kristina M. Ropella, Robert C. Molthen, Steven Thomas Haworth, Judy R. Kersten, David C. Warltier, Paul S. Pagel

Biomedical Engineering Faculty Research and Publications

Restenosis caused by neointimal hyperplasia (NH) remains an important clinical problem after stent implantation. Restenosis varies with stent geometry, and idealized computational fluid dynamics (CFD) models have indicated that geometric properties of the implanted stent may differentially influence NH. However, 3D studies capturing the in vivo flow domain within stented vessels have not been conducted at a resolution sufficient to detect subtle alterations in vascular geometry caused by the stent and the subsequent temporal development of NH. We present the details and limitations of a series of post-processing operations used in conjunction with microfocal X-ray CT imaging and reconstruction to …

Interaction Of Visual And Proprioceptive Feedback During Adaptation Of Human Reaching Movements, Robert A. Scheidt, Michael A. Conditt, Emanuele L. Secco, Ferdinando A. Mussa-Ivaldi

Biomedical Engineering Faculty Research and Publications

People tend to make straight and smooth hand movements when reaching for an object. These trajectory features are resistant to perturbation, and both proprioceptive as well as visual feedback may guide the adaptive updating of motor commands enforcing this regularity. How is information from the two senses combined to generate a coherent internal representation of how the arm moves? Here we show that eliminating visual feedback of hand-path deviations from the straight-line reach (constraining visual feedback of motion within a virtual, “visual channel”) prevents compensation of initial direction errors induced by perturbations. Because adaptive reduction in direction errors occurred with …

Alterations In Wall Shear Stress Predict Sites Of Neointimal Hyperplasia After Stent Implantation In Rabbit Iliac Arteries, John F. Ladisa, Lars E. Olson, Robert C. Molthen, Douglas Anthony Hettrick, Phillip F. Pratt, Michael D. Hardel, Judy R. Kersten, David C. Warltier, Paul S. Pagel

Biomedical Engineering Faculty Research and Publications

Restenosis resulting from neointimal hyperplasia (NH) limits the effectiveness of intravascular stents. Rates of restenosis vary with stent geometry, but whether stents affect spatial and temporal distributions of wall shear stress (WSS) in vivo is unknown. We tested the hypothesis that alterations in spatial WSS after stent implantation predict sites of NH in rabbit iliac arteries. Antegrade iliac artery stent implantation was performed under angiography, and blood flow was measured before casting 14 or 21 days after implantation. Iliac artery blood flow domains were obtained from three-dimensional microfocal X-ray computed tomography imaging and reconstruction of the arterial casts. Indexes of …

Circumferential Vascular Deformation After Stent Implantation Alters Wall Shear Stress Evaluated With Time-Dependent 3d Computational Fluid Dynamics Models, John F. Ladisa, Lars E. Olson, Ismail Guler, Douglas Anthony Hettrick, Judy R. Kersten, David C. Warltier, Paul S. Pagel

Biomedical Engineering Faculty Research and Publications

The success of vascular stents in the restoration of blood flow is limited by restenosis. Recent data generated from computational fluid dynamics (CFD) models suggest that stent geometry may cause local alterations in wall shear stress (WSS) that have been associated with neointimal hyperplasia and subsequent restenosis. However, previous CFD studies have ignored histological evidence of vascular straightening between circumferential stent struts. We tested the hypothesis that consideration of stent-induced vascular deformation may more accurately predict alterations in indexes of WSS that may subsequently account for histological findings after stenting. We further tested the hypothesis that the severity of these …

Antegrade Iliac Artery Stent Implantation For The Temporal And Spatial Examination Of Stent-Induced Neointimal Hyperplasia And Alterations In Regional Fluid Dynamics, John F. Ladisa, Heidi T. Meier, Lars E. Olson, Judy R. Kersten, David C. Warltier, Paul S. Pagel

Biomedical Engineering Faculty Research and Publications

Neointimal hyperplasia remains an important problem after stent implantation. Previous investigations examining vascular responses to stent implantation and effects of drugs have used a retrograde deployment approach that may inadvertently alter the local fluid dynamics surrounding the stent. We present a model of antegrade iliac artery stent implantation that facilitates the analysis of stent-induced alterations in neointimal hyperplasia and wall shear stress in vivo. Methods: Stent delivery catheters were inserted through the left carotid artery in anesthetized rabbits (n=37). Catheters were advanced under fluoroscopic guidance to the distal iliac arteries, where the stent was deployed. Hemotoxylin and eosin …

An In Vitro Comparison Of The Rake Angles Between K3 And Profile Endodontic File Systems, David Y. Chow, Sheila E. Stover, James Bahcall, Andris Jaunberzins, Jeffrey M. Toth

Biomedical Engineering Faculty Research and Publications

The purpose of this study was to compare rake angles of the ProFile and K3 file systems. Twenty-five 40/0.06 taper files were obtained for each system. Five files from the same manufacturer were placed perpendicularly into a vial of Epoxicure Resin and left to set for 24 h. The set-ups were removed from the vials and each were sectioned 5 mm from the tip of the files and polished. A photomicrograph was taken of each file with 100× magnification. Five sets of ProFile and five sets of K3 files were processed in this manner. Images were captured digitally, and rake …

A Dynamic Neuro-Fuzzy Model Providing Bio-State Estimation And Prognosis Prediction For Wearable Intelligent Assistants, Yu Wang, Jack M. Winters

Biomedical Engineering Faculty Research and Publications

Background

Intelligent management of wearable applications in rehabilitation requires an understanding of the current context, which is constantly changing over the rehabilitation process because of changes in the person's status and environment. This paper presents a dynamic recurrent neuro-fuzzy system that implements expert-and evidence-based reasoning. It is intended to provide context-awareness for wearable intelligent agents/assistants (WIAs).

Methods

The model structure includes the following types of signals: inputs, states, outputs and outcomes. Inputs are facts or events which have effects on patients' physiological and rehabilitative states; different classes of inputs (e.g., facts, context, medication, therapy) have different nonlinear mappings to a …

A Physiologically Based Clinical Measure For Spastic Reflexes In Spinal Cord Injury, Ela N. Benz, T. George Hornby, Rita K. Bode, Robert A. Scheidt, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

Objective: To test the validity of the Spinal Cord Assessment Tool for Spastic reflexes (SCATS), a clinical tool intended to rate spastic motor behavior after spinal cord injury (SCI).

Design: By using correlational analyses, the SCATS was validated using concurrent measurements of kinematics and electromyograms and traditional assessments of spasms and spastic hypertonia.

Setting: Research laboratory (kinematics and electromyography) and outpatient medical clinic (traditional measures of spastic hypertonia).

Participants: Eleven people with SCI were used for kinematic and electromyographic measurements. Seventeen people with SCI were used for comparison with other clinical scales.

Interventions: Not applicable. …

A Real-Time Haptic/Graphic Demonstration Of How Error Augmentation Can Enhance Learning, Yejun Wei, James L. Patton, Preeti Bajaj, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

We developed a real-time controller for a 2 degree-of-freedom robotic system using xPC Target. This system was used to investigate how different methods of performance error feedback can lead to faster and more complete motor learning in individuals asked to compensate for a novel visuo-motor transformation (a 30 degree rotation). Four groups of human subjects were asked to reach with their unseen arm to visual targets surrounding a central starting location. A cursor tracking hand motion was provided during each reach. For one group of subjects, deviations from the “ideal” compensatory hand movement (i.e. trajectory errors) were amplified with a …

Visual Error Augmentation For Enhancing Motor Learning And Rehabilitative Relearning, Yejun Wei, Preeti Bajaj, Robert A. Scheidt, James L. Patton

Biomedical Engineering Faculty Research and Publications

We developed a real-time controller for a 2 degree-of-freedom robotic system using xPC Target. This system was used to investigate how different methods of performance error feedback can lead to faster and more complete motor learning in individuals asked to compensate for a novel visuo-motor transformation (a 30 degree rotation). Four groups of normal human subjects were asked to reach with their unseen arm to visual targets surrounding a central starting location. A cursor tracking hand motion was provided during each reach. For one group of subjects, deviations from the "ideal" compensatory hand movement (i.e. trajectory errors) were amplified with …

Characterization Of Motor Adaptation And Limb Posture Regulation During Arm Reaching Movements Following Stroke, Robert A. Scheidt, Tina M. Stoeckmann

Biomedical Engineering Faculty Research and Publications

Whether attempting to pour water into a handheld glass, or simply trying to hold a young child's hand, many activities of daily living require interaction with unpredictable or uncertain mechanical environments. Here we describe a systems identification study that used a planar manipulandum to characterize how hemiparetic stroke survivors adapt reaching movements to novel mechanical environments. By analyzing trial-by-trial variations in hand path kinematics, we found that stroke survivors are less likely than neurologically-intact subjects to adjust motor commands for upcoming movements based on hand trajectory errors experienced on previous trials. This ability is most significantly compromised in subjects with …