Effects of Low Intensity Focused Ultrasound on Liposomes Containing Channel proteins.

The ability to reversibly and non-invasively modulate region-specific brain activity in vivo suggests Low Intensity Focused Ultrasound (LIFU) as potential therapeutics for neurological dysfunctions such as epilepsy and Parkinson's disease. While in vivo studies provide evidence of the bioeffects of LIFU on neuronal activity, they merely hint at potential mechanisms but do not fully explain how this technology achieves these effects. One potential hypothesis is that LIFU produces local membrane depolarization by mechanically perturbing the neuronal cell membrane, or activating channels or other proteins embedded in the membrane. Proteins that sense mechanical perturbations of the membrane, such as those gated by membrane tension, are prime candidates for activating in response to LIFU and thus leading to the neurological responses that have been measured. Here we use the bacterial mechanosensitive channel MscL, which has been purified and reconstituted in liposomes, to determine how LIFU may affect the activation of this membrane-tension gated channel. Two bacterial voltage-gated channels, KvAP and NaK2K F92A channels were also studied. Surprisingly, the results suggest that ultrasound modulation and membrane perturbation does not induce channel gating, but rather induces pore formation at the membrane protein-lipid interface. However, in vesicles with high MscL mechanosensitive channel concentrations, apparent decreases in pore formation are observed, suggesting that this membrane-tension-sensitive protein may serve to increase the elasticity of the membrane, presumably because of expansion of the channel in the plane of the membrane independent of channel gating

Cellular Mechanisms of Action Associated with Transcranial Ultrasound for Modulation and its Acoustic Characterization through Skull

Recent in vivo modulation of region-specific brain activity suggests that Low Intensity Focused Ultrasound (LIFU) may be a non-invasive alternative therapy for drug-delivery applications and the treatment of neurological diseases, including epilepsy and Parkinson’s disease.Despite these recent successes, failure to reproduce published results continues to plague the field due to the limited understanding of cellular mechanisms that underlie neuromodulation and the impact of skull on targeting accuracy. The objective of this thesis is to help bridge these knowledge gaps and better understand non-invasive transcranial focused ultrasound modulation. While hypotheses exist explaining the mechanism underlying ultrasound modulation, they largely remain untested. It has been suggested that mechanical perturbation of cellular membranes with embedded protein channels using ultrasound has an impact on ion channel kinetics, resulting in depolarization, and ultimately, increased neural activity. In particular, this thesis investigates the hypothesis explaining the mechanical perturbation as a result of pure acoustic radiation forces using simplified in vitro models, including Large-Conductance Mechanosensitive Channels (MscL) and non-mechanically stimulated channels. The outcome revealed an increase in efflux through proteoliposomes regardless of the channel type except at the highest concentration of mechanosensitive channel (MS) model where a lowering efflux trend was noticed. These unexpected results suggest that focused ultrasound does not modulate the gating of ion channels, but instead effects the permeability of the membrane itself or protein-membrane interface. Also a dual effect of membrane stretch enhancement and pore formation is observed only at high MS channel concentration.In addition, to prepare for in vivo efficacy studies, the present dissertation characterizes the ultrasonic beam scatter and focal shifts that occur as ultrasound passes through a rat skull for a specific set of parameters. The results have shown significant beam shape deformation and target shift due to the skull. This suite of studies improved our understanding of the mechanism associated with LIFU-based stimulation at the molecular level, while also exploring how LIFU can be applied with greater accuracy and precision in vivo. In addition, insights gleaned from this approach are expected to promote new avenues of clinical applications for the treatment of drug delivery, gene therapy and neurological illnesses

Effects of Low Intensity Focused Ultrasound on Liposomes Containing Channel proteins.

The ability to reversibly and non-invasively modulate region-specific brain activity in vivo suggests Low Intensity Focused Ultrasound (LIFU) as potential therapeutics for neurological dysfunctions such as epilepsy and Parkinson's disease. While in vivo studies provide evidence of the bioeffects of LIFU on neuronal activity, they merely hint at potential mechanisms but do not fully explain how this technology achieves these effects. One potential hypothesis is that LIFU produces local membrane depolarization by mechanically perturbing the neuronal cell membrane, or activating channels or other proteins embedded in the membrane. Proteins that sense mechanical perturbations of the membrane, such as those gated by membrane tension, are prime candidates for activating in response to LIFU and thus leading to the neurological responses that have been measured. Here we use the bacterial mechanosensitive channel MscL, which has been purified and reconstituted in liposomes, to determine how LIFU may affect the activation of this membrane-tension gated channel. Two bacterial voltage-gated channels, KvAP and NaK2K F92A channels were also studied. Surprisingly, the results suggest that ultrasound modulation and membrane perturbation does not induce channel gating, but rather induces pore formation at the membrane protein-lipid interface. However, in vesicles with high MscL mechanosensitive channel concentrations, apparent decreases in pore formation are observed, suggesting that this membrane-tension-sensitive protein may serve to increase the elasticity of the membrane, presumably because of expansion of the channel in the plane of the membrane independent of channel gating

Design and Implementation of an Electronic Health Record‐Integrated Hypertension Management Application

Background High blood pressure affects approximately 116 million adults in the United States. It is the leading risk factor for death and disability across the world. Unfortunately, over the past decade, hypertension control rates have decreased across the United States. Prediction models and clinical studies have shown that reducing clinician inertia alone is sufficient to reach the target of ≥80% blood pressure control. Digital health tools containing evidence‐based algorithms that are able to reduce clinician inertia are a good fit for turning the tide in blood pressure control, but careful consideration should be taken in the design process to integrate digital health interventions into the clinical workflow. Methods We describe the development of a provider‐facing hypertension management platform. We enumerate key steps of the development process, including needs finding, clinical workflow analysis, treatment algorithm creation, platform design and electronic health record integration. We interviewed and surveyed 5 Stanford clinicians from primary care, cardiology, and their clinical care team members (including nurses, advanced practice providers, medical assistants) to identify needs and break down the steps of clinician workflow analysis. The application design and development stage were aided by a team of approximately 15 specialists in the fields of primary care, hypertension, bioinformatics, and software development. Conclusions Digital monitoring holds immense potential for revolutionizing chronic disease management. Our team developed a hypertension management platform at an academic medical center to address some of the top barriers to adoption and achieving clinical outcomes. The frameworks and processes described in this article may be used for the development of a diverse range of digital health tools in the cardiovascular space