Blood clotting plays a heavy contribution to the mortality and morbidity in patients with diabetes mellitus. In blood clotting, the interaction between platelet glycoprotein Ib (GPIb) and blood protein von Willebrand Factor (VWF) is a catch bond, a bond whose lifetime increases under tensile force. Current, identification of this single-molecule behavior of a catch bond is useful but insufficient to understand behavior with multiple molecules known as clusters. It is recognized that patients with diabetes mellitus have higher levels of VWF and GPIb but there is no existing flow assay that accurately demonstrates the difference in thrombosis flow in diabetics. In addition, there is no definitive conclusion on the influences of the amount and geometry of the catch bond between GP1b and VWF in clusters. A recent innovation in the Thomas Lab has developed a DNA origami nanostructure that allows control over the number and spacing of ligands in a cluster, facilitating the study of clusters of catch bonds. I designed a method to quantify the nanostructure-presented ligands on a surface using 96-wellplate reader. This method was used to characterize the effect of cluster size on platelet rolling behavior. The result of the method suggests using quenching low concentration of biotin-4-fluorescein had the highest accuracy and was able to be picked up by the 96 well plate reader. The method allows observation seen in platelet rolling behavior over these surfaces that are cluster-size dependent rather than concentration-dependent. This will introduce a new assay for diabetic studies and further our understand difference in platelets rolling behavior over clusters between diabetic patients and non-diabetic patients.

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide and has been established as a risk factor for neurodegenerative diseases such as Alzheimer’s disease (AD). The progression of AD is characterized by intracellular aggregates of phosphorylated tau protein, which is mainly found in neurons and plays an important role in the stabilization of microtubules. One of the mechanisms that may contribute to tau aggregation is decreased tau clearance by the glymphatic system, a pathway that clears solutes from the brain. This fluid movement is facilitated by the astrocytic water channel aquaporin-4 (AQP4) which is primarily localized to the astrocytic endfeet that line perivascular channels surrounding the brain vasculature. Prior studies demonstrate that solute clearance along these pathways is slowed following TBI, and that there is a loss of perivascular localization of AQP4. Based on these findings we hypothesized the loss of perivascular localization of AQP4 may impair interstitial tau clearance and promote neurodegeneration. We first tested this hypothesis by examining whether loss of perivascular AQP4 following TBI promotes tau pathology in a transgenic PS19 mouse that spontaneously develops tau pathology. We then evaluated whether deletion of perivascular AQP4 in an alpha-syntrophin knock-out mouse promotes tau pathology both in the presence and absence of TBI, and when crossed with a PS19 tauopathy mouse. Alpha-syntrophin is a protein that anchors AQP4 and is important in perivascular localization; therefore, deletion of alpha-syntrophin results in loss of localization of AQP4 and impairment of clearance. We assessed levels of pathological tau using histology on the transgenic mice and crosses both with and without TBI. If validated, our findings may suggest that loss of perivascular AQP4 may increase the brain’s vulnerability to tau aggregation and neurodegeneration following TBI and provide the basis for potential treatment to prevent the development of post-traumatic neurodegeneration.