HOUSTON, TX. – 9 Feb 11
USRP Intern Investigates Matters of the Heart
By: Heather L. Ogletree
When Ariane Callender stepped onto the grounds of Johnson Space Center (JSC) in Houston, she did not know what to expect. She was far from her native New Orleans and far from her university, the Georgia Institute of Technology. “Unlike most of the other interns, I didn’t know a bunch of NASA facts before I got here,” recollected Callender. And with a clean slate, Callender began her exploration of the world known as NASA JSC.
In the fall of 2010, the Undergraduate Student Research Project (USRP) offered Callender the opportunity to participate in a 15 week hands-on, mentored project with NASA Mentors Steven Platts and Christian Westby. Together, they worked on a project entitled, “Characterizing Methods of Measuring Flow Mediated Dilation (FMD) of the Brachial Artery.”
Callender explained, “My project deals with methods of monitoring endothelial health.” Endothelium are flat cells that line the interior surface of blood vessels, forming an interface between circulating blood in a vein or artery and the rest of the vessel wall. Endothelial cells ultimately determine the health of your blood vessels and play a major role in preventing cardiovascular disease.
Callender and crew conducted FMD tests on 8 subjects, 4 male and 4 females, to determine the best location for the occlusion cuff, which constricts the brachial artery. It is somewhat likened to an advanced type of blood pressure test. She said, “There has been debate about where the occlusion cuff should be placed; at the upper arm or at the forearm. In the study I conducted, a FMD test was run using both cuff placements.”
During her exit presentation, Callender described the benefits and disadvantages of each placement. By placing it on the upper arm, the flow after occlusion is stronger, but it causes subjects discomfort and does not generate well-defined pictures. By placing the occlusion cuff on the forearm, the flow is weaker, but it produces better images and there is minimal discomfort.
“After analyzing all ultrasound images, no statistical differences were found between the two placements,” noted Callender.
Therefore, it is just as effective to conduct these tests on the forearm as the upper arm, yet the forearm provides the added benefits of clearer images and less discomfort. Callender indicated, “For some time now, the Cardio Lab [at JSC] has been interested in making the switch to measuring FMD at the forearm and now they have the knowledge and proof to do so.”
According to Callender, endothelial dysfunction can be caused by the conditions of long-duration flights, so “an FMD test is a way for the Cardiovascular Lab to monitor endothelial health and the overall health of the cardiovascular system of astronauts.”
Now that Callender is at the end of her 15 week experience, she observed, “Coming in with a blank slate about NASA has made this experience that much more enriching.... I’m glad I’m leaving JSC as more of a NASA-fanatic than when I started.”
Callender is currently studying biomedical engineering at the Georgia Institute of Technology and hopes to one day “establish an engineering firm that designs and develops medical devices and artificial organs.”
When Callender told her friends she was a NASA USRP intern, they asked, “Well aren’t you just doing busy work around the office?” To this she responded, “My experience has been far from that. I’m doing work on a day-to-day basis that is as important as the work being done by my co-workers in the next room. I know when my internship ends that my work will be used in future studies to better monitor cardiovascular health.”