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Tools from molecular biology, combined with in vivo optical imaging techniques, provide new mechanisms for noninvasively observing brain processes. Current approaches primarily probe cell-based variables, such as cytosolic calcium or membrane potential, but not cell-to-cell signaling. We devised cell-based neurotransmitter fluorescent engineered reporters (CNiFERs) to address this challenge and monitor in situ neurotransmitter receptor activation. CNiFERs are cultured cells that are engineered to express a chosen metabotropic receptor, use the G(q) protein-coupled receptor cascade to transform receptor activity into a rise in cytosolic [Ca(2+)] and report [Ca(2+)] with a genetically encoded fluorescent Ca(2+) sensor. The initial realization of CNiFERs detected acetylcholine release via activation of M1 muscarinic receptors. We used chronic implantation of M1-CNiFERs in frontal cortex of the adult rat to elucidate the muscarinic action of the atypical neuroleptics clozapine and olanzapine. We found that these drugs potently inhibited in situ muscarinic receptor activity.

We present a cell based system and experimental approach to characterize agonist and antagonist selectivity for ligandgated ion channels (LGIC) by developing sensor cells stably expressing a Ca2+ permeable LGIC and a genetically encoded Förster (or fluorescence) resonance energy transfer (FRET)-based calcium sensor. In particular, we describe separate lines with human α7 and human α4β2 nicotinic acetylcholine receptors, mouse 5-HT3A serotonin receptors and a chimera of human α7/mouse 5-HT3A receptors. Complete concentration-response curves for agonists and Schild plots of antagonists were generated from these sensors and the results validate known pharmacology of the receptors tested. Concentrationresponse relations can be generated from either the initial rate or maximal amplitudes of FRET-signal. Although assaying at a medium throughput level, this pharmacological fluorescence detection technique employs a clonal line for stability and has versatility for screening laboratory generated congeners as agonists or antagonists on multiple subtypes of ligandgated ion channels. The clonal sensor lines are also compatible with in vivo usage to measure indirectly receptor activation by endogenous neurotransmitters. [ABSTRACT FROM AUTHOR]

Understanding the epidemiology and ecology of yellow fever in endemic regions is critical for preventing future outbreaks. Ghana is a high-risk country for yellow fever. In this study we estimate the disease burden, ecological cycles, and areas at risk for yellow fever in Ghana based on historical outbreaks. We identify 2387 cases and 888 deaths (case fatality rate 37.7%) from yellow fever reported in Ghana from 1910 to 2022. During the approximately 30-year periods before and after implementation of routine childhood vaccination in 1992, the reported mean annual number of cases decreased by 80%. The geographic distribution of yellow fever cases has also changed over the past century. While there have been multiple large historical outbreaks of yellow fever in regions throughout Ghana, recent outbreaks have originated in northern regions. Comparing the locations where yellow fever outbreaks have emerged, we find patterns with seasons and different ecological transmission cycles. Using an ecological niche modeling framework, we predict areas in Ghana that are similar to where prior yellow fever outbreaks have originated based on temperature, precipitation, vegetation, and human population density. We find that these predictions differ depending on the ecological cycles of outbreaks. Ultimately, these findings and methods could be used to inform further subnational risk assessments for yellow fever in Ghana and other high-risk countries., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Judson et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)