Revacept, an inhibitor of platelet adhesion in symptomatic ...
The Effects of Shear Stress and L- arginine on Platelet Activation and Adhesion
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Transcript of The Effects of Shear Stress and L- arginine on Platelet Activation and Adhesion
Jeffrey Fontenot, REU Student
To seal off any broken or leaking blood vessels
Protecting damaged tissue while it heals
http://biomed.brown.edu/Courses/BI108/BI108_2005_Groups/10/webpages/plateletslink.htm
Over-activity◦ Clots and thrombi
form in unnecessary places or situations
◦ Thrombi may become larger than needed
◦ Heart attack and stroke may result
Under-activity◦ Clots do not form
when needed◦ Excessive bleeding◦ Wounds not healing
quickly or properly
The end goal ◦ Develop processes and devices that
can measure platelet activity◦ Diagnose platelet problems or
dysfunction in the clinical setting Intermediate goal
◦ Show that L-arginine decreases platelet adhesion
◦ Show that higher shear stress will increase platelet adhesion
Reproducing previous results◦ Positive control◦ Constant flow rate◦ Change L-arginine
concentrations from 0 to 25 µM/L
New work◦ Use different shear
stresses ranging from 1 to 15 dynes/cm2
◦ Use two different concentrations of L-arginine, 0 and 20 µM/L
Cut out micro channels Layer-by-Layer self
assembly Manifold and syringe
pump Calculate flow rate from
the desired shear stress◦
Bovine blood is collected and spun down to separate the Platelet Rich Plasma (PRP) which settles on the top
PRP travels down through the channel for one minute. The channels are rinsed with PBSEach channel is dyed with acridine orange
Each channel is photographed 22 times
The images are processed through a MatLab code
The average percent coverage is calculated in Excel
The positive control results
The current work results
Shear stress and L-arginine do have effects on platelet adhesion
Increasing shear stress appears to decrease adhesion◦ Possibly due to sodium citrate,
Yasuo et al. Source of errors
Correct the errors The results appear to
be opposite of the expected
There are more factors than originally expected◦ The anticoagulant may
play a role◦ Is there a delay between
activation and adhesion◦ Is the thrombus forming
and breaking up
Dr. Steven JonesMelanie GroanLouisiana Tech UniversityNational Science Foundation