Scanless two-photon voltage imaging.

Two-photon voltage imaging has long been heralded as a transformative approach capable of answering many long-standing questions in modern neuroscience. However, exploiting its full potential requires the development of novel imaging approaches well suited to the photophysical properties of genetically encoded voltage indicators. We demonstrate that parallel excitation approaches developed for scanless two-photon photostimulation enable high-SNR two-photon voltage imaging. We use whole-cell patch-clamp electrophysiology to perform a thorough characterization of scanless two-photon voltage imaging using three parallel illumination approaches and lasers with different repetition rates and wavelengths. We demonstrate voltage recordings of high-frequency spike trains and sub-threshold depolarizations from neurons expressing the soma-targeted genetically encoded voltage indicator JEDI-2P-Kv. Using a low repetition-rate laser, we perform multi-cell recordings from up to fifteen targets simultaneously. We co-express JEDI-2P-Kv and the channelrhodopsin ChroME-ST and capitalize on their overlapping two-photon absorption spectra to simultaneously evoke and image action potentials using a single laser source. We also demonstrate in vivo scanless two-photon imaging of multiple cells simultaneously up to 250 µm deep in the barrel cortex of head-fixed, anaesthetised mice.

Safety and efficacy comparison of Tenecteplase and Alteplase for clinically suspected large vessel occlusion strokes without thrombectomy.

INTRODUCTION: Tenecteplase is a thrombolytic with higher fibrin affinity, and is potentially better in clot lysis. A higher spontaneous recanalization rate for large vessel occlusions strokes (LVO) had been shown in comparison studies with Alteplase. Results of the LVO studies reflect the composite effect of the thrombolytic and thrombectomy, as patients would be treated by thrombectomy had they not been recanalized by intravenous thrombolysis alone. Thrombectomy is not readily available in many parts of the world. Our study aimed to compare the outcomes of suspected LVO patients treated with Tenecteplase versus Alteplase only, without the confounding effect of thrombectomy. METHODS: This is a retrospective review. Data of patients given Tenecteplase from May 2020 to August 2023, and those given Alteplase 0.9 mg/kg from January 2019 to August 2023 were retrieved. (Due to fluctuation in supply of Tenecteplase during the COVID pandemic, some large vessel occlusion patients were given Alteplase.) Patients with anterior circulation, clinically suspected large vessel occlusion strokes (defined as National Institutes Health Stroke Scale (NIHSS) score >= 6, plus cortical signs or hyperdense vessel sign), with thrombolysis given within 4.5 hours of stroke onset were analyzed. Patients with thrombectomy done were excluded. Safety and efficacy outcomes were compared. RESULTS: There were 245 Tenecteplase treated patients treated between 1st May 2020 and 31st August 2023, and 732 patients were treated with Alteplase between 1st January 2019 to 31st August 2023. Out of these, 148 Tenecteplase patients and 138 Alteplase 0.9 mg/kg patients fulfilled the study criteria. The symptomatic intracerebral haemorrhage rate was non-significantly lower in the Tenecteplase group (2.1% versus 5.8%, p=0.13). There were no significant differences in the rate of >=8 points NIHSS improvement (23.6% versus 23.7%, p=1) or the >= 4 points improvement (40.5% versus 40.7%, p=1) at 24 hours. At 3 months, 21.6% of Tenecteplase patients had good functional outcome (modified Rankin scale (mRS) 0-2), compared to 26.3% in the Alteplase group (p=0.40). CONCLUSION: In this pragmatic study of clinically suspected anterior circulation LVO patients without thrombectomy, outcome solely reflects the effects of Tenecteplase. Tenecteplase showed comparable safety and efficacy to Alteplase. But the result should be interpreted with caution in view of its small sample size and non-randomized study design.

Ionic Hydrogel for Accelerated Dopamine Delivery via Retrodialysis.

Local drug delivery directly to the source of a given pathology using retrodialysis is a promising approach to treating otherwise untreatable diseases. As the primary material component in retrodialysis, the semipermeable membrane represents a critical point for innovation. This work presents a new ionic hydrogel based on polyethylene glycol and acrylate with dopamine counterions. The ionic hydrogel membrane is shown to be a promising material for controlled diffusive delivery of dopamine. The ionic nature of the membrane accelerates uptake of cationic species compared to a nonionic membrane of otherwise similar composition. It is demonstrated that the increased uptake of cations can be exploited to confer an accelerated transport of cationic species between reservoirs as is desired in retrodialysis applications. This effect is shown to enable nearly 10-fold increases in drug delivery rates from low concentration solutions. The processability of the membrane is found to allow for integration with microfabricated devices which will in turn accelerate adaptation into both existing and emerging device modalities. It is anticipated that a similar materials design approach may be broadly applied to a variety of cationic and anionic compounds for drug delivery applications ranging from neurological disorders to cancer.

High-throughput brain activity mapping and machine learning as a foundation for systems neuropharmacology.

Technologies for mapping the spatial and temporal patterns of neural activity have advanced our understanding of brain function in both health and disease. An important application of these technologies is the discovery of next-generation neurotherapeutics for neurological and psychiatric disorders. Here, we describe an in vivo drug screening strategy that combines high-throughput technology to generate large-scale brain activity maps (BAMs) with machine learning for predictive analysis. This platform enables evaluation of compounds' mechanisms of action and potential therapeutic uses based on information-rich BAMs derived from drug-treated zebrafish larvae. From a screen of clinically used drugs, we found intrinsically coherent drug clusters that are associated with known therapeutic categories. Using BAM-based clusters as a functional classifier, we identify anti-seizure-like drug leads from non-clinical compounds and validate their therapeutic effects in the pentylenetetrazole zebrafish seizure model. Collectively, this study provides a framework to advance the field of systems neuropharmacology.

Investigation of the Subcellular Neurotoxicity of Amyloid-ß Using a Device Integrating Microfluidic Perfusion and Chemotactic Guidance.

Alzheimer's disease (AD) is a neurodegenerative disorder with the histopathological hallmark of extracellular accumulation of amyloid-ß (Aß) peptide in brain senile plaques. Though many studies have shown the neural toxicity from various forms of Aß peptides, the subcellular mechanisms of Aß peptide are still not well understood, partially due to the technical challenges of isolating axons or dendrites from the cell body for localized investigation. In this study, the subcellular toxicity and localization of Aß peptides are investigated by utilizing a microfluidic compartmentalized device, which combines physical restriction and chemotactic guidance to enable the isolation of axons and dendrites for localized pharmacological studies. It is found that Aß peptides induced neuronal death is mostly resulted from Aß treatment at cell body or axonal processes, but not at dendritic neurites. Simply applying Aß to axons alone induces significant hyperactive spiking activity. Dynamic transport of Aß aggregates is only observed between axon terminal and cell body. In addition to differential cellular uptake, more Aß-peptide secretion is detected significantly from axons than from dendritic side. These results clearly demonstrate the existence of a localized mechanism in Aß-induced neurotoxicity, and can potentially benefit the development of new therapeutic strategies for AD.

Autonomous system for cross-organ investigation of ethanol-induced acute response in behaving larval zebrafish.

Ethanol is widely consumed and has been associated with various diseases in different organs. It is therefore important to study ethanol-induced responses in living organisms with the capability to address specific organs in an integrative manner. Here, we developed an autonomous system based on a series of microfluidic chips for cross-organ investigation of ethanol-induced acute response in behaving larval zebrafish. This system enabled high-throughput, gel-free, and anesthetic-free manipulation of larvae, and thus allowed real-time observation of behavioral responses, and associated physiological changes at cellular resolution within specific organs in response to acute ethanol stimuli, which would otherwise be impossible by using traditional methods for larva immobilization and orientation. Specifically, three types of chips ("motion," "lateral," and "dorsal"), based on a simple hydrodynamic design, were used to perform analysis in animal behavior, cardiac, and brain physiology, respectively. We found that ethanol affected larval zebrafish in a dose-dependent manner. The motor function of different body parts was significantly modulated by ethanol treatment, especially at a high dose of 3%. These behavioral changes were temporally associated with a slow-down of heart-beating and a stereotyped activation of certain brain regions. As we demonstrated in this proof-of-concept study, this versatile Fish-on-Chip platform could potentially be adopted for systematic cross-organ investigations involving chemical or genetic manipulations in zebrafish model.