2009 Symposium Abstracts from Physical Therapy, Medical Technology, and Exercise Science

Normotensive Salt-Resistant Individuals and the Nighttime Dip in Blood Pressure

Michael Holder, Meghan Wenner, Jody Greaney, Juliann Galaszewski, and William B. Farquhar

Introduction: Blood pressure follows a circadian rhythm, peaking in early morning and decreasing, or dipping, at night. If blood pressure does not dip at night, this is considered nondipping, and is associated with a variety of physiological abnormalities. Dietary salt is recognized to negatively alter the nighttime blood pressure response in salt sensitive hypertensive individuals. The following study observes salt resistant normotensive individuals, because they do not have a direct increase in blood pressure when receiving a dietary salt load. Purpose: The purpose of the following study is to determine if a high salt diet attenuates the night time dip in blood pressure, in salt resistant normotensive individuals. Methodology/Results: Fourteen subjects (10 males and 4 females) participated in this study. All had normal blood pressure and were salt resistant. Individuals who were salt resistant were characterized as having less than a 5 mmHg change in blood pressure from a low to a high sodium diet. These subjects were studied during a baseline (100 mmol/day), low salt (20 mmol/day) and high salt (350 mmol/day) period. Twenty-four hour ambulatory blood pressures were measured on the last day of each trial. There was no significant difference in nighttime blood pressure dip between baseline, low and high sodium concentrations. Conclusions: The present study demonstrated that dietary salt did not affect the nighttime dip in blood pressure in normotensive salt resistant subjects. This suggests that in this particular population dietary salt may not play a particular role in the nighttime dip in blood pressure.

Relationship between the bone and muscle disparities in the lower extremities
of individuals with hemiplegic cerebral palsy.

Eleanor A. Kelly, Jacques Riad, Brianne Mulrooney, Joshua T. Kirby, Freeman Miller, and Christopher M. Modlesky

Cerebral palsy (CP), a disorder of movement and posture, causes restricted muscle growth, reduced coordination, and diminishes participation in physical activity. Hemiplegic CP contributes to the underdevelopment of bone, but these consequences are usually limited to the affected extremities. One factor very strongly related to bone development is the force of muscle contraction on bone. However, it is unknown if disparities in bone development in adolescents with hemiplegic CP are due to disparities in muscle mass. The purpose of this study was to determine if muscle groups in the thigh and hip were related to bone volume and strength in the femur of adolescents with hemiplegic CP. Images of the thighs and hips were collected from adolescents with hemiplegic CP using a Phillips 1.5 Tesla MRI scanner. Cortical bone volume and estimated bone strength of the middle third of the femur and muscle mass of the quadriceps, hamstrings and hip adductors were determined using custom software designed with Interactive Data Language (Research Systems, Boulder, CO). Although the quadriceps, hamstring, and hip adductor muscle masses were all related to cortical bone volume and estimated strength in the femur of the affected and unaffected lower extremities of adolescents with hemiplegic CP, only the disparity in quadriceps muscle mass (i.e., lower in the affected side) was related to disparities in bone (i.e., lower in the affected side). Future studies are needed to determine if rehabilitation programs that target specific muscle groups can improve bone development in adolescents with hemiplegic CP. Supported by FoU Kärnsjukhuset Skövde Sweden and the NIH (HD 50530).

Ankle joint compensations to Passive Dynamic Ankle Foot Orthosis use

Alissa V. Kregling¹, Kota Takahashi³, Elisa Schrank², Steven J. Stanhope^1,2,3
¹Department of Health, Nutrition and Exercise Science; ²Department of Engineering; ³Biomechanics and Movement Science Interdisciplinary Program

Passive dynamic ankle foot orthoses (PD-AFOs) are braces that act like rotational springs to mimic muscle moments during gait. Our hypothesized theory of absolute moment substitution predicts individuals will compensate to PD-AFO use by decreasing the magnitude of muscle effort by precisely the level of assistance provided by the PD-AFO. The purpose of my research was to test this theory during normal gait. Gait data from two healthy adults (S1, S2), walking at a constant velocity, were analyzed with and without wearing a PD-AFO designed to replicate 50% of natural ankle stiffness during stance. S1 walked with a consistent velocity (.79 statures/s), while S2 walked with a slightly faster velocity (.88 vs. .91 statures/s; p=.002) with and without the AFO. Peak ankle moments during the stance phase of gait decreased 16.84% (p=.0006) and -4.5% (p=.0773) from un-braced levels for S1 and S2. During the braced condition, the peak AFO moment was well below the 50% un-braced targeted value for both subjects (26.488% and 21.157% of the un-braced peak; p-values < .0005). In addition, ankle ROM was significantly decreased in the braced vs. un-braced condition for S1: 9° vs. 33° and S2: 8° vs. 24°. Both subjects also demonstrated an increased natural ankle moment in early stance during the braced condition and a shorter duration of the second rocker (earlier heel rise), indicating a compensatory strategy requiring an increased utilization of the ankle joint musculature. Therefore, the theory of absolute moment substitution was not supported by the findings of this study.

Interactions of Eristostatin with Natural Killer and Melanoma Cells

Alaa Mahmoud and Mary Ann McLane
Department of Medical Technology

The ability of Natural Killer (NK) cells to lyse cancerous cells has been well documented. Interestingly, it has previously been shown that 4μM eristostatin, a snake venom disintegrin from Eristocophis macmahoni, elicits a 2-fold increase in the lytic ability of TALL-104 (NK-like) cells towards SBcl2, a radial growth phase melanoma cell line. Based on these findings, it was hypothesized that eristostatin can also enhance the lytic ability of NK cells toward melanoma cells (MV3, M24met, SBcl2, C8161, WM164, and 1205Lu). The lytic ability of NK cells toward SBcl2 was enhanced in the presence of 3μM eristostatin as hypothesized, but the other melanoma cell lines did not exhibit this trend. / In addition to the cytotoxicity assays, three-dimensional (3D) experiments were carried out to study the interactions of eristostatin with melanoma cells in a model that more closely resembles in vivo conditions. The 3D studies were carried out in Matrigel®, a basement membrane harvested from Engelbreth-Holm-Swarm mouse sarcoma. Matrigel® is comprised primarily of laminin, followed by collagen IV, heparin sulfate proteoglycans, entactin/nidogen, and growth factors. We carried out a live/dead assay in Matrigel® to see if eristostatin has an effect on live/dead ratios in a 3D environment. Cells in Matrigel® with or without eristostatin did not exhibit a difference in either spatial configuration or live/dead ratios. It should be noted that eristostatin does not have inhibitory activity against cell adhesion to laminin or collagen. Since eristostatin inhibited melanoma cell migration on fibronectin (FN), future experiments will incorporate FN into the matrix.

The Correlation Between Asymmetry and Functional Walking in Stroke Patients.

Jill M McElligott, Christine L Malecka, and Darcy S Reisman
Department of Physical Therapy

An asymmetric gait is most commonly linked to walking dysfunction in people with hemiparesis after a stroke. Spatiotemporal asymmetry has been observed in stance durations between the paretic and non-paretic limbs, step length, and in the duration of double support following a stroke. The consequences, however, of asymmetry in regards to walking, energy cost, balance, and disability remain unclear. The purpose of this project is to investigate the relationship between single limb support (SLS), step length asymmetry and measures of balance, gait function and disability in hopes of determining whether an asymmetrical gait is related to functional walking in stroke survivors. / We hypothesize that in chronic stroke survivors, spatiotemporal gait asymmetry is positively correlated with functional walking ability. Thirteen subjects with right or left hemiparesis ages 60.77 ± 8.85 were asked to walk on a treadmill at their self-selected speed. Results showed a positive correlation between temporal asymmetric gait and energy during walking in persons post stroke (r = 0.74338; SLS and r = 0.63185 stance). Negative correlation was found between temporal asymmetric gait and walking speed in persons post stroke (r = -0.49430; SLS and r = -0.34727 stance). No correlation was found for spatial asymmetry (step length) with either speed or efficiency. In addition, spatiotemporal symmetry did not correlate with measures of functional gait.

A Study into Research in Fields Relating to Neonatal and Pediatric Pulmonology

John Mosko, Thomas Shaffer, M. Elena Rodriguez, Kevin Dysart, Yan Zhu, and Aaron Chidekel,
Nemours Research Lung Center/Biomedical Research Department, Alfred I. DuPont Hospital for Children, Wilmington, DE;
Thomas Jefferson Medical College, Philadelphia, PA; Temple University School of Medicine, Philadelphia, PA

The Summer Scholars Program research opportunity for the summer was spent working in the Nemours Research Lung Center (NRLC) at the A.I. DuPont Hospital for Children under the direction of Thomas Shaffer, MSE, Ph.D. The NRLC has been working on several projects for an extended period of time, for both papers already published and projects awaiting publication. The projects worked with, therefore, include: High Flow Nasal Cannula Animal Studies utilizing different mixtures of gases, under the direction of Kevin Dysart, M.D. performed at the Animal Intensive Care Unit; Respiratory Function Assessment Studies using different lung function techniques in Patients Undergoing One Lung Ventilation, directed by M. Elena Rodriguez, M.D.; Clinical Studies in Patients with Respiratory, Cardiopulmonary and Orthopedic disorders with potential pulmonary complications, studied by Drs. Rodriguez, Shaffer and Chidekel (these clinical studies are performed in the Non-Invasive Pulmonary Evaluation Laboratory (NIPEL) as part of the NRLC); and Calu-3 Cell Culture Studies under the direction of Yan Zhu, M.D. Research was compounded with activities including visits to the Operating Room, Catheterization Laboratory, Neonatal Intensive Care Unit (NICU), working in a specially designated cell-culture room, and visits to the hospital clinic to interact with patients and clinical staff. My primary focus was on the methodology and history of the Calu-3 cells used by the NRLC.

THE EFFECT OF HISTOCHEMICAL STAINING
ON THE QUALITY & YIELD OF RNA IN MUSCLE CELLS OBTAINED WITH LMD

Tammy Mulrooney; Justin Jesse; Bobbie Boyce; and Carol Barone

Delaware Technical & Community College, Histotechnology Core Lab / Nemours, Wilmington DE 19803

Laser microdissection (LMD) is best performed on frozen sections. Routine staining of paraffin embedded tissue can compromise results. Upholding the integrity of the RNA can be difficult because it is easily degraded by staining components which affect both the quality and yield of total RNA produced with staining for LMD. This project focuses on the use of histochemical stains as a possible staining option, verses unstained or routinely stained muscle tissue for LMD. Using standard techniques for the preparation of RNA on frozen tissue, we offer a modified histochemical staining protocol for use with LMD and to determine the affect of histochemical stains on the quality and yield of RNA with LMD. The author would like to thank INBRE (Grant No. 2P20RR016472-09) for their support of this project.

Ankle Motions of Individuals with Hemiparesis in Response to Electrical Stimulation during Walking: a four-footswitch

Thorne-FitzGerald, Dylan J. ¹; Kesar, Trisha M.²; Binder-Macleod, Stuart A.²
¹Department of Health, Nutrition and Exercise Science and ²Department of Physical Therapy, University of Delaware

Individuals who experience a stroke have paresis on one side of their body, which results in asymmetrical walking patterns. A gait training program that has recently been developed at UD, FastFES, combines fast walking on a treadmill with functional electrical stimulation (FES) of the paretic ankle muscles to improve the quality, speed, and efficiency of stroke patients’ gait. FES is delivered based on events of the gait cycle, relayed by footswitch sensors attached to the patients’ shoe. The current footswitch setup for FES uses two footswitches, one under the heel and one under the toe. However, we recently observed that with the current two footswitch setup, dorsiflexion stimulation was initiated while the foot was still on the ground, before true toe-off occured. Due to this premature onset of dorsiflexion stimulation with the two-footswitch setup, the ankle plantarflexion angles at toe-off were adversely affected. Thus, in the current study, to improve the accuracy of delivery of dorsiflexor stimulation, we are testing a novel footswitch setup consisting of four footswitches one under the heel and three footswitches under the forefoot. Walking patterns of 5 post-stroke individuals will be compared during walking with FES using the four- versus two-footswitch setups. The findings of this study will help determine the best method to accurately time the delivery of FES during the gait training program. *Funding for this work was provided by NIH Grant R01 NR010786 and the University of Delaware Life Sciences Undergraduate Research Program .

L-arginine and microvascular function in chronic kidney disease.

Wuroh Timbo, Jennifer DuPont, and David G. Edwards
Department of Healkth, Nutrition and Exercise Science

Cardiovascular disease (CVD) is a major cause of death in chronic kidney disease (CKD) patients. Endothelial dysfunction is a characteristic of CKD, and has been demonstrated to lead to the progression of CKD and CVD. A major contributor to endothelial dysfunction is the vast increase in levels of asymmetric dimethyl-arginine (ADMA) which competes with L-arginine for nitric oxide synthase (NOS) in patients with CKD. The purpose of this study is to determine if a relative deficit of L-arginine contributes to a reduced NO mediated cutaneous vasodilation in patients with moderate to severe CKD. 6 subjects (3 CKD, 3 healthy control) were recruited for study participation. Red blood cell flux is measured via laser Doppler flometry with local heating coupled with 3 intradermal microdialysis sites on the ventral side of the forearm: Ringer’s solution (control), L-NAME (NOS inhibition), and L-arginine (treatment). A standard, non-painful heating protocol is used with baseline temperature set to 33° C, increased 0.5° C every 5 seconds until 42° C is obtained. Cutaneous vascular conductance (CVC) is calculated as FLUX/MAP (mean arterial pressure) and normalized to maximal CVC (%CVCmax) achieved during 28mM sodium nitroprusside (Tloc 43° C ) infusion in all three MD sites. A 2 X 2 ANOVA will be used to compare %CVCmax between L-arginine and Ringer solution in the two groups. Funding was provided by the Howard Hughes Medical Institute, the McNair Scholars Program, and Grant DK80469.

Utilizing Resting Metabolic Rate to Evaluate Safe and Effective Weight Loss

Annette Torre, Simone Church, John Burrows, and Mark Lafferty
Delaware Technical & Community College

Most dieticians make dietary recommendations for total caloric intake base upon height and weight prediction equations. Using indirect calorimetry to determine resting metabolic rate [RMR] we found that 74% [52/70] of the clients we tested were found to have an actual value which was lower than the predicted RMR value, indicating that direct assessment of RMR is superior to the use of prediction equations. Strikingly, the use of overestimated prediction equations for caloric intake can adversely result in the addition of body fat mass [BFM] in clients and subsequent increases in their body mass index [BMI]. RMR values less than that predicted indicates a decrease of lean muscle mass [LMM]. This negative imbalance between LMM and BFM has been shown to have a direct correlation to the onset of Type II diabetes. / We measured BMI and used indirect calorimetry to analyze RMR to determine the specific dietary caloric intake needs of our clients. Clients with RMR values less than predicted were prescribe a higher percentage of resistance training exercises to increase their LMM and RMR. All subjects analyzed thus far demonstrated a decrease in BMI and an increase or stable RMR, indicating an increase in LMM. Additionally, some subjects showed decreased dependency on prescribed medications. / Funding for this project was provided by NIH NCRR INBRE grant to Delaware 2P20RR016472. /

Beri	Gilsdorf	Kregling	Mosko	Torre
Bond	Hall	Lewis	Mulrooney, Ta
Darocki	Holder	Mahmoud	Thorne-FitzGerald
Flynn	Kelly	McElligott	Timbo