Different levels of doxorubicin in the brain were accomplished through alteration of the microbubble concentration. These results are encouraging and provide an important framework for compound screening assay future studies aimed at local disruption of the BBB for delivery of macromolecular agents to the brain.

Several avenues of transcapillary passage after ultrasound sonication have been identified. These include transcytosis, passage through endothelial cell cytoplasmic openings, opening of tight junctions and free passage through injured endothelium [26]. One study investigated the integrity of the tight junctions (TJs) in rat brain microvessels after BBB disruption by ultrasound bursts (1.5-MHz) in combination with Optison

[27]. BBB disruption, as evidenced by leakage of i.v. administered horseradish peroxidase Selumetinib mouse (HRP) and lanthanum chloride, was paralleled by the apparent disintegration of the TJ complexes, the redistribution and loss of the immunosignals for occludin, claudin-5 and ZO-1. At 6 and 24 h after sonication, no HRP or lanthanum leakage was observed and the barrier function of the TJs, as indicated by the localization and density of immunosignals, appeared to be completely restored. The results of these studies demonstrate that the effect of ultrasound upon TJs is very transient, lasting less than 4 h. Although much effort has been undertaken to demonstrate the safety of BBB opening with ultrasound and microbubbles, further work is needed to elucidate the molecular effects of this application. Recent data demonstrate that at the upper thresholds of acoustic pressure for safe BBB opening a reorganization of gap-junctional plaques in both neurons and astrocytes may occur [28]. This is important because gap junctions allow transfer of information between adjacent cells and are responsible for tissue homeostasis. Likewise, there is evidence that focused ultrasound-induced opening of the BBB in the

presence of ultrasound contrast agents can lead to increased ubiquitinylation of proteins in neuronal cells [29], indicating that brain molecular stress pathways are affected by this treatment. Nevertheless, this new technology for delivering drugs across the BBB will offer Methamphetamine exciting opportunities for treatment of a variety of brain diseases in the future. “
“Intravenous thrombolysis with rt-PA is the only approved therapy for treating acute ischemic stroke and needs to be administered within the first 4.5 h after symptom onset [1]. Among other factors, the speed and completeness of recanalization, and successive reperfusion of ischemic brain tissue is associated with final infarct size, restoration of function, and finally clinical outcome. With i.v. rt-PA only, there is a rather low percentage of patients achieving early (30–40%) and complete (18%) recanalization [2].