G protein-coupled receptors (GPCRs) are embedded in phospholipids that strongly influence drug-stimulated signaling. Anionic lipids are particularly important for GPCR signaling complex formation, ...but a mechanism for this role is not understood. Using NMR spectroscopy, we explore the impact of anionic lipids on the function-related conformational equilibria of the human A
adenosine receptor (A
AR) in bilayers containing defined mixtures of zwitterionic and anionic phospholipids. Anionic lipids prime the receptor to form complexes with G proteins through a conformational selection process. Without anionic lipids, signaling complex formation proceeds through a less favorable induced fit mechanism. In computational models, anionic lipids mimic interactions between a G protein and positively charged residues in A
AR at the receptor intracellular surface, stabilizing a pre-activated receptor conformation. Replacing these residues strikingly alters the receptor response to anionic lipids in experiments. High sequence conservation of the same residues among all GPCRs supports a general role for lipid-receptor charge complementarity in signaling.
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•Development of microfluidic reaction scheme for synthesis of fused indoline ring systems by flow chemistry.•Green chemistry approach with clean reaction profile, good yields and ...quick scalability.•Continuous-flow in a microfluidic reactor for interrupted Fischer indolization reaction.•General utility to rapidly produce indoline scaffolds and intermediates of industrial importance.
This study describes our development of a microfluidic reaction scheme for the synthesis of fused indoline ring systems found in several bioactive compounds. We have utilized a continuous-flow microfluidic reactor for the reaction of hydrazines with latent aldehydes through the interrupted Fischer indolization reaction to form fused indoline and azaindoline products. We have identified optimal conditions and evaluated the scope of this microfluidic reaction using various hydrazine and latent aldehyde surrogates. This green chemistry approach can be of general utility to rapidly produce indoline scaffolds and intermediates in a continuous manner.
The development of an in vivo procedure for the induction of massive proliferation, directed migration, and neurodifferentiation (PMD) in the damaged adult central nervous system would hold promise ...for the treatment of human neurodegenerative disorders such as Parkinson's disease. We investigated the in vivo induction of PMD in the forebrain of the adult rat by using a combination of 6-hydroxydopamine lesion of the substantia nigra dopaminergic neurons and infusions of transforming growth factor α (TGFα) into forebrain structures. Only in animals with both lesion and infusion of TGFα was there a rapid proliferation of forebrain stem cells followed by a timed migration of a ridge of neuronal and glial progenitors directed toward the region of the TGFα infusion site. Subsequently, increasing numbers of differentiated neurons were observed in the striatum. In behavioral experiments, there was a significant reduction of apomorphine-induced rotations in animals receiving the TGFα infusions. These results show that the brain contains stem cells capable of PMD in response to an exogenously administered growth factor. This finding has significant implications with respect to the development of treatments for both acute neural trauma and neurodegenerative diseases.
The 826 human G protein‐coupled receptors (GPCRs) are involved in nearly every physiological process and comprise the largest class of “druggable” proteins. For over the past decade, crystal and ...cryo‐EM structures have focused on revealing molecular details of GPCR interactions with small molecules and intracellular partner proteins, which are well‐established regulators of GPCR function. More recently, literature data from biological and biophysical studies have demonstrated that phospholipids found in the endogenous membrane environment also control GPCR function and act as allosteric modulators. In particular, phospholipids with charged headgroups have been reported to be especially important regulators of GPCR function and facilitate the formation of signaling complexes.
Using nuclear magnetic resonance (NMR) spectroscopy in aqueous solutions, we investigated the structural basis for the regulation of GPCR activity by phospholipids in nanodiscs containing the human A2A adenosine receptor (A2AAR), a representative class A GPCR. Lipid nanodiscs containing mixtures of uncharged and charged phospholipids were produced, yielding homogeneous preparations over a wide range of lipid compositions. NMR data of uniformly stable‐isotope labeled A2AAR showed the receptor was properly folded in lipid nanodiscs and shared a similar global conformation to detergent micelle preparations of A2AAR. Using 19F NMR with conformationally‐sensitive probes located at the A2AAR intracellular surface, we systematically investigated the influence of lipid composition over a wide range of mixtures of charged and uncharged phospholipids. A2AAR complexes with antagonists showed almost no response to variation in lipid composition. In striking contrast to this, A2AAR complexes with agonists showed a clear response to changes in the relative proportion of charged phospholipids. NMR data of agonist complexes in nanodiscs containing lower proportions of charged lipids were highly similar to data of antagonist complexes, showing a higher proportion of neutral lipids negated the efficacy of bound agonists. As the proportion of charged phospholipids increased, the relative population of an A2AAR active conformation also increased. The dependence of the receptor response to bound agonists on lipid composition suggested specific interactions between lipid headgroups and charged amino acids at the A2AAR intracellular surface underlie the regulation of activity. Results from this study indicate that lipid composition must be carefully selected in studies of GPCRs in nanodiscs. Our data also provide a potential molecular mechanism for how changes in membrane composition, due to disease for example, can directly impact the efficacy of drugs.
Double-blinded, prospective laboratory animal study.
To examine whether intraoperative spinal cord stimulation (SCS) inhibits the development of spine surgery-induced hypersensitivity.
Managing ...postoperative pain after spine surgery is challenging, and as many as 40% of patients may develop failed back surgery syndrome. Although SCS has been shown to effectively reduce chronic pain symptoms, it is unknown whether intraoperative SCS can mitigate the development of central sensitization that causes postoperative pain hypersensitivity and potentially leads to failed back surgery syndrome after spine surgery.
Mice were randomly stratified into three experimental groups: (1) sham surgery, (2) laminectomy alone, and (3) laminectomy plus SCS. Secondary mechanical hypersensitivity was measured in hind paws using von Frey assay one day before and at predetermined times after surgery. In addition, we also performed a conflict avoidance test to capture the affective-motivational domain of pain at selected time points postlaminectomy.
Mice that underwent unilateral T13 laminectomy developed mechanical hypersensitivity in both hind paws. Intraoperative SCS applied to the exposed side of the dorsal spinal cord significantly inhibited the development of hind paw mechanical hypersensitivity on the SCS-applied side. Sham surgery did not produce any obvious secondary mechanical hypersensitivity in the hind paws.
These results demonstrate that spine surgery for unilateral laminectomy induces central sensitization that results in postoperative pain hypersensitivity. Intraoperative SCS after laminectomy may be able to mitigate the development of this hypersensitivity in appropriately selected cases.
The potential complications associated with gastroparesis in the perioperative setting for patients with multiple sclerosis (MS) are inadequately recognized. While gastroparesis is commonly ...associated with diabetes mellitus-induced neuropathy and postsurgical complications, its prevalence and impact on patients with MS are less understood. This is particularly crucial as the systemic autoimmune nature of MS may extend its neurological effects to the gastrointestinal (GI) tract. In this context, we present a case wherein undiagnosed gastroparesis significantly contributed to postoperative challenges, leading to delayed extubation in a patient with MS. This underscores the importance of considering gastroparesis as a potential differential diagnosis and developing a comprehensive approach to evaluating and managing MS patients, which may help mitigate perioperative complications and inform tailored anesthetic management strategies.
The potential complications associated with gastroparesis in the perioperative setting for patients with multiple sclerosis (MS) are inadequately recognized. While gastroparesis is commonly ...associated with diabetes mellitus-induced neuropathy and postsurgical complications, its prevalence and impact on patients with MS are less understood. This is particularly crucial as the systemic autoimmune nature of MS may extend its neurological effects to the gastrointestinal (GI) tract. In this context, we present a case wherein undiagnosed gastroparesis significantly contributed to postoperative challenges, leading to delayed extubation in a patient with MS. This underscores the importance of considering gastroparesis as a potential differential diagnosis and developing a comprehensive approach to evaluating and managing MS patients, which may help mitigate perioperative complications and inform tailored anesthetic management strategies.
Exchange-coupled interfaces are pivotal in exploiting two-dimensional (2D) ferromagnetism. Due to the extraordinary correlations among charge, spin, orbital and lattice degrees of freedom, layered ...magnetic transition metal chalcogenides (TMCs) bode well for exotic topological phenomena. Here we report the realization of wafer-scale Cr2Te3 down to monolayer (ML) on insulating SrTiO3(111) and/or Al2O3(001) substrates using molecular beam epitaxy. Robust ferromagnetism persists in the 2D limit. In particular, the Curie temperature TC of 2 ML Cr2Te3 increases from 100 K to ~ 120 K when proximitized to topological insulator (TI) (Bi,Sb)2Te3, with substantially boosted magnetization as observed via polarized neutron reflectometry. Our experiments and theory strongly indicate that the Bloembergen-Rowland interaction is likely universal underlying TC enhancement in TI-coupled magnetic heterostructures. The topological-surface-enhanced magnetism in 2D TMC enables further exchange coupling physics and quantu
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