Amyloid beta (Aβ) oligomers and phosphorylated tau (p-tau) aggregates are increasingly identified as potential toxic intermediates in Alzheimer's disease (AD). In cortical AD synapses, p-tau co-localizes with Aβ, but the Aβ and p-tau peptide species responsible for synaptic dysfunction and demise remains unclear. The present experiments were designed to use high-speed cell sorting techniques to purify synaptosome population based on size, and then extend the method to physically isolate Aβ-positive synaptosomes with the goal of understanding the nature of Aβ and tau pathology in AD synapses. To examine the purity of size-gated synaptosomes, samples were first gated on size; particles with sizes between 0.5 and 1.5 microns were collected. Electron microscopy documented a homogenous population of spherical particles with internal vesicles and synaptic densities. Next, size-gated synaptosomes positive for Aβ were collected by fluorescence activated sorting and then analyzed by immunoblotting techniques. Sorted Aβ-positive synaptosomes were enriched for APP and for Aβ oligomers and aggregates; immunolabeling for p-tau showed a striking accumulation of p-tau aggregates compared to the original homogenate and purified synaptosomes. These results confirm co-localization of Aβ and p-tau within individual synaptic terminals and provide proof of concept for the utility of flow sorting synaptosomes.

Discs 1.6 mm in diameter trephined from corneal collagen shields were used to deliver acyclovir (ACV) to the cornea of mice inoculated with herpes simplex virus type 1 (HSV-1). In the first minute after application to the cornea, there was a 23% decrease of ACV in the discs. After the first minute, ACV clearance from the discs appeared to be exponential with a half-life of 21 minutes. Treatment given 3 times a day reduced HSV-1 titer in tear film, corneal tissue, and trigeminal ganglia. This animal model should be useful to conserve novel potential anti-viral drugs undergoing initial screening.

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