Medicine, Biosciences, Biotechnology Symposium Chair:
Medicine, Biosciences, Biotechnology Symposium Peer Reviewers:
| Session Codes | ||
|---|---|---|
| *xxxnn | Both an oral presentation and a poster | |
| xxxPnn | Poster Only |
MBB01
Photopolymerized Hydrogel Barriers Prevent Thrombosis and Restenosis after
Balloon Injury: The Roles of Medial and Luminal Growth Factors
Jennifer West, PhD, T.N. Law Assistant Professor, Rice University,
Department of Bioengineering
Jeffrey A. Hubbell, PhD, ETH (Swiss Federal Institute of Technology),
Zurich, Switzerland, Department of Biomedical Engineering
Friday, 9:00am–9:25am
An interfacial photopolymerization technique has been developed to allow the synthesis
of thin (<50 µm) hydrogel barriers on the luminal surface of arteries. These hydrogels
are non-thrombogenic and biodegradable. The polymerization process does not damage the
underlying tissue. Application of hydrogel barriers following balloon injury of the
rat common carotid artery has been shown to eliminate thrombosis (2 hr post-injury,
n = 7, p < 0.005) and to reduce intimal thickening by approximately 80% (14 d post-injury,
n = 7, p < 0.001). The efficacy of this short-term, strictly localized treatment for
prevention of restenosis is believed to be due to the complete blockade of interaction
with thrombus-derived mitogens and chemotactic agents, such as platelet-derived growth
factor (PDGF) and thrombin. To probe this possibility, experiments were carried out
utilizing non-degradable hydrogel barriers to block thrombosis and contact with blood
combined with localized delivery of PDGF and thrombin. Neither of these substances
stimulated intimal thickening in the absence of thrombosis, whereas PDGF delivery in
the presence of thrombosis increased the intimal thickening response approximately two-fold.
Thus, we conclude that while PDGF is a factor in the restenosis cascade, it requires the
activity of a blood-derived cofactor.
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MBB11
Effect of a Novel Keratin Biomaterial on Wound Healing: In Vitro and
Preclinical Results
C.R. Blanchard, PhD, Manager, Materials Development Section, Southwest
Research Institute
H. Cohly, PhD, Research Associate, University of Mississippi Medical Center
A.J. Siller, Scientist, Materials Development Section, Southwest Research Institute
M. Angel, Student, University of Mississippi Medical Center
B. Rogers, Professor, University of Mississippi Medical Center
J. Thompson, Student, University of Mississippi Medical Center
G.E. Abraham III, Student, University of Mississippi Medical Center
R.A. Smith, MD, Plastic Surgeon, Jackson Plastic Surgery Clinic
Friday, 9:30am to 9:55 am
Partial and full thickness wounds often require the application of topical dressings
for protection and to promote healing. Keratins, major structural proteins of all
epithelial cell types, appear to play an important role in the re-epithelialization
process of wound healing. The effect of a new keratin biomaterial (KP) derived from
human hair on proliferation of keratinocytes (K), fibroblasts (F), endothelial cells (E),
and T cells was studied. In addition, CD/hairless rats (N=28) were randomly divided
into two groups. Group A wounds were untreated while Group B wounds were treated with
keratin every other day. The KP powder was prepared by cleaning, drying and comminuting
human hair harvested from 13-19 year old males. Cells exposed to the KP biomaterial
revealed that lymphocytes did not proliferate, activated T cells were not inhibited,
keratinocytes proliferated profusely, fibroblasts proliferated modestly, and microvascular
endothelial cells proliferated profusely. Non-proliferation of lymphocytes is an indication
that the KP biomaterial is non-immunogenic. Failure to inhibit active T cells shows that
the KP biomaterial does not interfere with the body's normal immune response. Clinically
observed epithelialization in the planimetry studies at day 4 indicated 98.5% coverage in
the treated and 76.7% in the non-treated rats (p<0.05). Cellular hyperesponsiveness,
coupled with low antigenicity, demonstrates the enhanced wound healing and mitogenic
characteristics of keratin. The preclinical study demonstrates that KP enhances healing
in partial thickness wounds.
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MBB03
Transmyocardial Laser Revascularization (TMLR)
Kƒmuran A. Kadipasaoglu, PhD, Texas Heart Institute, Cardiovascular
Surgical Research
L.A. Stutts, MA, Texas Heart Institute, Cardiovascular Surgical Research
Laboratories
H.B. Cihan, MD, Texas Heart Institute, Cardiovascular Surgical Research
D. A. Cooley, MD, Texas Heart Institute, Cardiovascular Surgical Research
O.H. Frazier, MD, Texas Heart Institute, Cardiovascular Surgical Research
Friday, 10:00am–10:25am
TMLR for the treatment of refractory angina is performed using a CO2 laser with a fixed power output of 800 W and a variable pulse energy and pulse duration. Laser energy is transmitted via an articulating arm placed in direct contact with the target tissue. The laser delivers single pulses on the R wave of the EKG waveform. The epicardium is exposed via a left anterolateral thoracotomy. Transmural channels are placed in the beating heart. Reversal of ischemia is believed to occur when blood penetrates the changnels during systole and perfuses the subendocardium via the sinusoidal plexus. The procedure is undergoing safety and efficacy evaluation in randomized clinical trials in the US.
TMLR using the 800 W CO2 Laser is safe in the patient population described in this
study, effectively relieves anginal symptoms, improves exercise tolerance, and increases
left ventricular freewall perfusion for at least 12 months.
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MBB04
Cardiopulmonary Bypass Techniques for Neonates and Infants
Akif Undar, PhD, Director, Perfusion Research, Congenital Heart Surgery,
Texas Children's Hospital, and Director, Pediatric Perfusion Research, Cullen
Cardiovascular Research Laboratory, Texas Heart Institute, and Instructor,
Section of Congenital Heart Surgery, Baylor College of Medicine
Alexis Palacios-Macedo, MD, Clinical Fellow, Congenital Heart Surgery,
Texas Children's Hospital and Baylor College of Medicine
Angela Diamond, MD, Clinical Fellow, Congenital Heart Surgery, Texas
Children's Hospital and Baylor College of Medicine
O. Howard Frazier, MD, Chief, Transplantation Service, Director, CV Surgery
Research, Texas Heart Institute
Charles D. Fraser, MD, Chief, Congenital Heart Surgery, Texas Children's
Hospital and Assistant Professor, Department of Surgery, Baylor College of Medicine
Friday, 10:30am–10:55am
Every year, approximately 10,000 neonates are born in the United States with congenital
heart defects, that require a cardiopulmonary bypass (CPB) procedure during infancy.
Although complex surgeries can be done with routine techniques with a lower mortality
rate than ever before; the brain injury after CPB is still a significant problem (among
10 to 30% of post-op pediatric heart patients). The common approach has been to repair
the congenital heart defect treating neonates and infants as small adults. However,
especially neonates, respond to CPB more dramatically and rapidly than adults. For
example, cerebral blood flow (CBF), cerebral metabolism (CMRO2), and the CBF/CMRO2 ratio
in neonates are significantly higher than adults due to the increased metabolic demand
for neuronal growth. Therefore, neonates and infants are not just small adults.
Non-pulsatile perfusion, the level of cerebral perfusion pressure (CPP), acid-base
management technique during cooling and rewarming, rate of pump flow, degree of
hemodilution and hypothermia, and duration of circulatory arrest may influence the
brain injury. All of these parameters are controlled during CPB and a little adjustment
of any of these parameters may have a significant effect for the outcome of the patient.
Currently, the effects of each of these parameters are under investigation by several
institutions to develop a safer cardiopulmonary bypass circuit for neonates and infants.
We will focus on the effects of pulsatile vs. non-pulsatile perfusion during pediatric
open-heart surgery in this paper.
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MBB05
The Future of Diagnostic X-ray and CT Imaging
Frank A. DiBianca, PhD, Director and Crippled Children's Foundation
Professor, University of Tennessee at Memphis, School of Biomedical Engineering
Friday, 1:00pm–1:25pm
The first window into the human body for medical diagnosis was discovered at the end of the nineteenth century when Professor Konrad Roentgen observed that the mysterious "X-rays" he had recently discovered could penetrate through the body and record images of internal human anatomy on photographic film. Other than by means of highly invasive exploratory surgery, this x-ray imaging technique remained the sole method of studying internal anatomy for over half a century until the advent of alternative diagnostic techniques such as ultrasound, nuclear isotope imaging, CT scanning and, most recently, magnetic resonance imaging. Despite these major advances, diagnosis with x-ray beams still remains the most often used technique due to its generality, high resolution and low cost.
This talk will survey the relative strengths of the various imaging techniques, summarize
current directions in x-ray and CT imaging and attempt to prognosticate their future
directions and ability to remain competitive in the 21st century.
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MBB06
Advances in Computer Technology are Creating New Opportunities for
Engineering in Cardiology
Sheryl S. Prucka, PE, President and Founding Partner of Prucka Engineering, Inc.
Friday, 1:30pm–1:55pm
In the past decade, the application of computerized techniques has dramatically improved health care providers ability to diagnose and treat a variety of cardiac conditions. The trend has led toward safer and less invasive diagnostic methods. As an example, echocardiography is now routinely used as a noninvasive preliminary technique for evaluating ventricular function. Previously, catheterization studies were required to perform such an evaluation, exposing the patient to the risk associated with an invasive procedure. In addition to improving diagnostic tools, computerized approaches to support interventional techniques have improved treatment efficacy and reduced both risk to the patient and the cost of procedures.
Current research in cardiology is providing many opportunities for the continued application
of computerized techniques. Several computerized methods for 3-dimentional localization
of catheters have recently been developed, enabling engineers to create accurate 3-D
representations of the chamber, and the catheter within it, during an electrophysiologic study.
New techniques in imaging, including the use of Intra-Vascular Ultrasound (IVUS) are
providing substantial opportunity for the development of new computer-based tools for the
analysis and 3-D reconstruction of the chamber or vessel where the image data is collected.
Recent advances in computer technology are providing engineers with a powerful foundation
which can be effectively used to develop tools to address rapidly changing needs in the
field of cardiology, and in medicine in general.
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*MBB07
Joint Kinematics
Rita M. Patterson, PhD, Assistant Professor
C.K. Hebert, MD, Assistant Professor
William L. Buford, Jr., PhD, Assistant Professor
Steven F. Viegas, MD, Professor, The University of Texas Medical
Branch, Galveston, Department of Orthopaedic Surgery and Rehabilitation
Friday, 2:30pm–2:55pm
Because of the body's structural complexity and morphological variations, a reference database of normal anatomy and kinematics will provide valuable reference information to facilitate diagnosis and treatment of various injuries and diseases.
The skin on fresh frozen cadaver extremities was dissected and triad pins placed into various bones defining different joints. Transverse images of the joint and pins were obtained with a GE 9800 CT generating contiguous slices 1.5 mm thick. The data was processed and then visualized in 3D computer space in AVS on an Evans and Sutherland Graphic workstation. Optoelectronic-stereo-cinephotogrammetry motion analysis (OSMA) was then performed on the joints during motion.
Results of the OSMA motion data were combined with CT geometric data to create an animation of the motion. Range of motion (ROM), angles between bones, and instantaneous screw axes (ISA) were calculated.
This new combination of motion analysis and 3D reconstruction of CT images affords a high
speed, dynamic analysis of kinematics. Human Joint motion is complex consisting of
both rotation and translation components.
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*MBB08
Quantifying Muscle Activation Patterns By Means of Clustering and
Classification
Christina A. Batson, Senior Student, University of Alabama, Department
of Mechanical Engineering
Beth A. Todd, PhD, Assistant Professor, The University of Alabama,
Department of Mechanical Engineering
Tanya G. Cole, Senior Student, The University of Alabama,
Department of Mechanical Engineering
Linda C. Shackelford, MD, Head of the Bone and Mineral Physiology
Laboratory, NASA, Johnson Space Center, Life Sciences Research Laboratories
Friday, 3:00pm–3:25pm
Research has proven that disuse of bones, such as that seen in a non-gravitational
environment, results in bone mineral density (BMD) loss. Under weightless conditions
in orbit, astronauts have a tendency to exhibit bone mineral loss in their spine and
lower extremities with no net changes in the upper extremities. The main areas of
concern include the lumbar spine, femoral neck, and calcaneus regions. It has been
found that heavy resistive exercises are the most successful countermeasures for
increasing BMD in these areas, while chemical therapies are showing potential.
NASA has been exploring these options as a means of preventing BMD loss during space flight.
Effective countermeasures for BMD loss found through this research can also be used to
prevent and treat osteoporotic bone disorders.
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MBB09
Quantifying Muscle Activation Patterns By
Means of Clustering and Classification
Vonda L. Hart, MS, University of Houston, Bioengineering Research Center,
Department of Electrical and Computer Engineering
Ben H. Jansen, PhD, University of Houston, Bioengineering Research Center,
Department of Electrical and Computer Engineering
Demetrios C. Mavrofrides, MS, University of Houston, Bioengineering
Research Center, Department of Electrical and Computer Engineering
Caroline W. Stegink Jansen, PhD, University of Texas Medical Branch,
Galveston, School of Allied Health, Department of Physical Therapy
Friday, 3:30pm–3:55pm
The electromyogram (EMG) provides a measure of a muscle's involvement in the
execution of a motor task. Successful completion of an activity, such as walking,
depends on the efficient motor control of a group of muscles. We have developed a
technique to quantify the intricate phasing and activation levels of a muscle group
during a motor task. At the core of our method is a multidimensional representation
of the EMG activity observed during a single stride. This representation, referred
to as a "trajectory", is obtained by plotting the activity of one muscle against that
of other muscles. A hierarchical clustering procedure is used to identify representative
classes of muscle activity patterns, referred to as "templates". Once the templates
are identified, single strides from the various sessions recorded are classified by
matching them to the templates. Differences in gait patterns between walking conditions
can be reflected by changes in the distribution of strides matching individual templates,
e.g., one condition results in fewer strides matching a particular template than another
condition. Two experimental conditions were used to determine the effectiveness of the
algorithm in differentiating between gait patterns. The conditions were horizontal and
inclined treadmill gait. Data were collected multiple times over several days.
Significant differences between horizontal and inclined gait were found, while the
ithin and between day variability was small.
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MBB10 - Withdrawn
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MBBP01
Integrating Physiological Data and Mathematical Models to
Understand Disease in Cardiac Ventricular Cells
Semahat S. Demir, PhD, Assistant Professor, School
of Biomedical Engineering, University of Tennessee - Memphis
The insights gained and results derived from studies on dogs and rats will enhance
our understanding of the heart, and provide us with better treatments for diseases in
human. Despite nearly five decades of histological, electrophysiological, pharmacological
and biochemical investigations, relatively little is known regarding the ionic mechanisms
underlying the action potential variation in the canine and rat ventricular myocytes
under different pathological conditions. Thus, the action potentials of dog and rat
continue to be a topic of considerable interest in cardiac electrophysiology and
mathematical modeling for several reasons. First, the canine ventricular action
potential is very similar to that of human. On the other hand, the rat ventricular
action potential is shorter and lacks a prominent plateau phase compared to those by
human, dog, guinea pig and rabbit. Second, mathematical modeling for ventricular cells
has been done in guinea pig and relatively less in rat, rabbit and dog. Furthermore,
the differences in ventricular membrane ionic currents, especially outward K+ currents
in different species have very important practical implications. Different drugs are
known to affect different ionic currents and to change action potential waveforms in
various mammalian heart preparations under different pathological (normal, tachycardia
induced heart failure diabetic, altered thyroid, and hypertrophied) conditions. A better
understanding of the role of the ionic currents that control repolarization in the
ventricular myocytes obtained from various species including dog and rat will provide
explanations for species differences in treatment and drug actions, and also promote
pharmacological research that may lead to the development of more specific drugs to be
used in humans. In short, the biophysically detailed quantitative dog and rat ventricular
cell models can provide good insights into the ionic basis of action potential variation
in epicardial and endocardial cells under a variety of disease conditions.
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MBBP02
Electrical Stimulus Application on a Cardiac Pacemaker Cell
Semahat S. Demir, PhD, Assistant Professor, School
of Biomedical Engineering, University of Tennessee - Memphis
A cardiac pacemaker (sinoatrial node, SAN) cell model (Demir et al 1994) was studied
to determine the phase-sensitive response of the sinoatrial node cell to a single
pulse and periodic pulses of hyperpolarizing electrical current. The simulation data
were presented in phase response curves (PRCs) for the single pulse and in entrainment
curves (ECs) for the periodically applied pulses. These graphical representations
provided a quantitative description of the phase-sensitivity behavior of the SAN cell
in rabbit. Our computations showed that the characteristics of the phase-sensitive
effects in PRCs and ECs are dependent upon the intensity of the stimulus and that the
PRCs and ECs represented the perturbations in the membrane properties of the pacemaker
cell caused by the hyperpolarizing stimulus. The mechanisms related to the changes in
the ionic currents due to the hyperpolarizing effects are explained in phase planes, in
terms of current-voltage plots. Our model depends on quantitative voltage clamp and action
potential data, thus it can provide reasonable estimates of the ionic currents and their
interactions in setting the pacemaker rate. We found out that the action potential
threshold determined by ICa,L was not affected by the perturbations. The currents
(INaCa, If, INa and ICa,T) that set the rate of diastolic depolarization were affected
by the perturbations. The changes in INaCa, If, INa and ICa,T during diastole determine
the rate of diastolic depolarization which results in delaying or advancing the following
action potential. This study provides a better understanding of the requirements and
mechanisms for controlling pacemaker activity of the heart during diastole.
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MBBP03 - Withdrawn
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