Abstracts from Medical Technology,
Physical Therapy, and Psychology
Undergraduate Summer Research Symposium August 14, 2003

Ordered alphabetically by student's last name


 
Movement Variability: A Reflection of Error or Goal-equivalence?
Effect of Movement Speed."

Tyesha Dwight, Jennifer Lynch, and John Scholz
Department of Physical Therapy

This study investigates how the nervous systemís use of motor redundancy is affected when reaching at different velocities, resulting in different joint interaction moments. Seated subjects reached at three different velocities with their left hand to point to targets placed in the left and right workspace within armís length. Movement time was recorded by an analog system and used to give feedback to the subject about movement speed. The uncontrolled manifold approach was used to determine how movement velocity effects joint motion variability. This approach partitions joint configuration variability into two components: (1) goal-equivalent joint combinations that lead to a stable hand path and (2) joint variability that changes the hand path. Preliminary results indicate that at the slower movement speed, overall joint configuration variability is higher than at the fastest condition. Nonetheless, most of that increase in variability is found to represent goal-equivalent joint combinations. This finding supports the notion that the control system is very good at stabilizing movement parameters such as the handís position along its movement path by channeling variability of the motor elements into goal-equivalent directions. TD funded by a Ronald E. McNair Scholarship. JL funded by Charles Peter White Fellowship.


 
 
Venous Hemodynamic Function in Young and Older Adults

Christopher-Michael Gale, Colin Young, Megan Wener, and William B. Farquhar
Department of Health and Exercise Science

While age-related stiffening of the vasculature has been well documented in the arteries of humans, much less is known about age-related alterations in the veins. Venous hemodynamic function is often quantified as "venous compliance;" that is, the slope of the pressure-volume (P-V) relationship. We hypothesized that venous compliance would be lowered in older adults. One older (65 y.o.) and 1 younger (20 y.o.) were studied. A mercury-in-silastic strain gauge was used to record the change in limb volume while a cuff around the thigh was deflated at a rate of 1 mmHg/sec. The P-V relationship was modeled using a quadratic regression, allowing for the estimation of venous compliance. The P-V relationship was shifted to the pressure axis in the older adult. Venous compliance was 65% lower in the older compared to the younger adult (0.08 vs. 0.023 ml/dl/mmHg). Pilot data suggest that venous compliance declines with age. The mechanisms underlying these age-related differences will be the focus of future research. The relationships between decreased venous compliance and vascular composition, sympathetic innervation, and hypertension will be the first to be explored.


 
 
 
Multilimb Coordination in Typically Developing Children

Lauren Glime, Michelle Eichinger, Sarah Trager, and Nancy Getchell
Human Performance Laboratory, Department of Physical Therapy

The purpose of this study is to determine how typically developing children coordinate their limbs while performing simultaneous, multilimb tasks.  In the future this study will be expanded to children with learning disabilities and comparisons will be made. A cross sectional design is being used for this study. Typically developing children of the ages 4, 6, 8, and 10 will be used as subjects as well as adult subjects.  There will be 12 participants of each age.  Participants completed six different conditions of walking and clapping in which both single and dual motor tasks will be completed. During some of the conditions, participants will match the beat of a metronome.  A GAITrite mat/sound system was used to collect the data of children.   The data gathered from this system is then processed through a LABVIEW program. At this point in the study data analyses of the adult subjects has begun. There are several statistics that are available on the adult subjects at this point; mean age is 24 and mean height is 171 cm. More information will be available on the results of the study as data reduction continues. This study was funded through a grant from the UD Research Foundation.


 
 
Visual Looming Selectively Activates a Nucleus in the Brain of Fishes

Vivek Patel, S. P. Gallagher, D.P.M. Northmore
Department of Psychology

Little is known of the function of nucleus isthmi (NI) in fish except that it responds erratically to visual stimulation. This experiment tested the hypothesis that NI specifically detects looming objects. Neural activity in the left NI of sunfish was recorded using a microelectrode. Neural activity was amplified (x 10,000), full wave rectified, and integrated with a time constant of 15ms.  The resulting signal, which represents the ďtotal amountĒ of activity generated by NI, was digitized by computer at 100-500 Hz. Realistic soccer balls were displayed in black and white on a gray background using a laptop computer screen 20 cm from the right eye, which was corrected for myopia in air with a contact lens.  Animation software simulated various trajectories of the ball in 3D space. Comparison was made with a real ball, moved by hand.  Both real and simulated balls approaching the eye generated a build-up of burst-like firing in NI; retreat along the same path usually elicited only a brief, initial burst.  Non-collision trajectories elicited less activity.  Unlike other visual stimuli, looming stimuli produced little habituation of responding. NI may serve a vital function in alerting the animal to the approach of threatening objects.


 
 
Possible Transcriptional Regulation of Melanoma Metastasis by HDAC2

Kari Reese, Carrie Paquette-Straub, and Mary E. Miele
Department of Medical Technology

Cancer progression results from deregulation of normal gene expression in cells.  For cancers to occur, the expression of oncogenes may be increased, and/or the expression of tumor suppressor and metastasis suppressor genes may be decreased.  It is likely that transcriptional regulators play a key role in cancer progression.  Histone deacetylase 2 (HDAC2) is a transcriptional repressor located on the long arm of chromosome 6, a region that is often mutated or deleted in melanoma cells and previously shown by our laboratory to harbor a metastasis-suppressor locus.  The hypothesis tested was that HDAC2 functions as a metastasis suppressor. RT-PCR studies using a variety of melanoma cell lines showed no correlation between RNA levels of HDAC2 and metastatic ability.  Since RNA levels do not necessarily correlate with protein activity, an experiment was designed to measure functional HDAC activity.  Total HDAC activity, determined using a fluorescent HDAC activity assay, was found to be greater in more highly metastatic cells.  These findings do not support the original hypothesis.  Therefore, we will focus future investigations towards other genes in this region as possible metastasis suppressors.  This project was funded by HHMI and PHS-CA 88876.

 
The Relationship of Head and Trunk Control to Shoulder-elbow Coordination 
During the Development of Reaching in Infants

Erin Salo, Anjana Bhat, J. C. Galloway
Department of Physical Therapy

Human infants begin moving as early as 8-10 weeks in utero.  Infants begin to gain head, trunk and limb control during the first months of postnatal life.  Studies suggest a link between head and trunk movements and purposeful control of the arms for reaching.  The purpose of this ongoing study is to investigate the relationship between changes in early arm movements and the associated development of head and trunk control.  Findings from this project provide a foundation for advancing rehabilitation for infants born at risk for developmental movement disorders. Four healthy, full term infants in each age group of 8 weeks, 12 weeks, 16 weeks, and 20 weeks old were observed with high-speed motion analysis and standard video as they interacted with either the experimenter or with toys.  Preliminary results suggest that infants of all ages spent time in multiple positions; 8-week-old infants spent more time leaning to the side or backward whereas 18-week-olds spent more time in the midline and in propped up positions.  Thus, significant changes in head and trunk control occur over these 10 weeks.  Additional analysis will reveal the relationship between these changes in head and trunk control and the development of successful reaching.  The University of Delaware Undergraduate Science and Engineering program provided funding for this study.


 
Point Mutations in Eristostatin, 
a Metastasis Suppressor 
from Snake Venom.

Apoorva Srivastava, Carrie Paquette-Straub,
andMary Ann McLane
Department of Medical Technology

Eristostatin, a disintegrin obtained from the venom of viper Eristicophis macmahoni, is known to suppress metastasis of mouse and human melanoma cell lines.  This project was undertaken to identify the amino acids essential for Eristostatinís suppressive ability.  Using Recombinant DNA technology, the gene for Eristostatin was mutated to code for alanine at targeted amino acid positions (12-18, 30-36).  Megaprimer PCR was used to introduce the mutations into Eristostatin gene containing plasmid which was then transformed into E. coli bacterial cells for cloning or expression of the protein.  K17A is ready for expression in BL-21 whereas R18A, W30A, D33A, Y34A, and T36A have been cloned in XL-10.  The other 6 attempted mutations were unsuccessful and efforts are underway for troubleshooting.  The different Eristostatin mutant proteins, once expressed, will then be compared with unmutated Eristostatin to test their relative in vitro interactions in cell-based assays and the relative suppressive ability in vivo using immunocompromised mice.  We expect to find significant decrease in some Eristostatin mutantsí anti-metastatic ability, indicating a crucial role of the specific amino acid in this inhibition.  The funding for this project was provided by the Howard Hughes Medical Institute and the National Cancer Institute (1R01CA098056-01MCL)


 
 
Molecular Basis of Metastasis Inhibition:  The Venom Protein Eristostatin

Claire Zelinskas, Carrie Paquette-Straub, and Mary Ann McLane
Department of Medical Technology

Eristostatin, from Eristicophis macmahoni, is a disintegrin that can inhibit murine and human melanoma metastasis in vivo.  The mechanism by which this is accomplished remains unknown.  I designed seven alanine mutants of the eristostatin gene in order to provide a panel of recombinant proteins with single amino acid changes.  A megaprimer polymerase chain reaction (PCR) technique which required a mutagenic primer was used.  The primer contained the correct alanine codon, and a restriction endonuclease site to confirm the presence of the mutation.  The mutated eristostatin insert was ligated into the expression vector pGEX-KG.  The cloning bacteria XL10 was transformed with the plasmid, and colony PCR and restriction digests were performed to verify the presence of the insert.  Expression bacteria BL21 were transformed with the plasmid, and colony PCR and restriction digests were used as above.  ErR24A is currently being expressed, and the remaining mutations are at interim stages of this process.  The panel of eristostatin mutants will be tested in functional assays against wildtype eristostatin in binding to human metastatic melanoma cells.  Upon completion of this project, we expect to define the motifs within eristostatin which contribute to its interaction with human melanoma cells.  Project funded by HHMI and NCI. 


 
Whatís the  Big Idea?  Childrenís Use of Actor Intent in Verb Learning

Jennifer M. Zosh and Roberta Michnick Golinkoff
Departments of Psychology and Education

When and how does a child learn that actions are not merely random, but rather that the actor has an intention?  This information is necessary for both the acquisition of language and the development of a theory of mind.  This study aims to examine the ability of children to discern the intent of an actor and to use that intent to learn verbs.  Using the Intermodal Preferential Looking Paradigm, children in two age groups, 19-22 months and 36-39 months, are shown an actor attempting to accomplish a goal (e.g., retrieve a brownie from a jar). They are then shown a scene that may lead to the goal, using actions that are both central (e.g., unscrewing the jar lid) and peripheral (e.g., wiping oneís brow) to the goal while hearing a novel verb label (e.g., Look! Sheís mimming!).  Then, using a split-screen presentation, they are simultaneously shown separate clips of the central and peripheral actions while hearing audio that asks them to look at the previously labeled action.  A preference for the central action (reflected by longer visual fixation times) would reveal both sensitivity to the intentions of others and the ability to exploit this information to learn verbs. JMZ funded by Undergraduate Research Program. Project funding from NSF Grant SBR9615391 to RMG and Kathy Hirsh-Pasek.



Links: Summer 2003 Undergraduate Research Symposium, Symposium Abstracts from other Colleges and Departments,
Undergraduate Research Summer Enrichment ProgramUnversity of Delaware Undergraduate Research Program, Howard Hughes Undergraduate Program.
Created 8 August 2003. Last up dated 20 August 2003 by Hal White
Copyright 2003, University of Delaware