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Designer receptors exclusively activated by designer drugs (DREADDs) are chemogenetic tools for remotely controlling cellular signaling, neural activity, behavior, and physiology. Using a structure-guided approach, we provide a peripherally restricted Gi-DREADD, hydroxycarboxylic acid receptor DREADD (HCAD), whose native receptor is minimally expressed in the brain, and a chemical actuator that does not cross the blood-brain barrier (BBB). This was accomplished by combined mutagenesis, analoging via an ultra-large make-on-demand library, structural determination of the designed DREADD receptor via cryoelectron microscopy (cryo-EM), and validation of HCAD function. Expression and activation of HCAD in dorsal root ganglion (DRG) neurons inhibit action potential (AP) firing and reduce both acute and tissue-injury-induced inflammatory pain. The HCAD chemogenetic system expands the possibilities for studying numerous peripheral systems with little adverse effects on the central nervous system (CNS). The structure-guided approach used to generate HCAD also has the potential to accelerate the development of emerging chemogenetic tools for basic and translational sciences., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The human MRGPRD protein is a member of the Mas-related G protein-coupled receptors (MRGPRs) that is involved in the sensing of pain, itch, and other inflammatory stimuli. As with other MRGPRs, MRGPRD is a relatively understudied receptor with few known agonists. The most potent small-molecule agonist of MRGPRD reported so far is β-alanine, with an affinity in the micromole range, which largely restricts its functional study. Here, we report two MRGPRD agonists, EP-2825 and EP-3945, that are approximately 100-fold more potent than β-alanine and determine the structures of MRGPRD-Gq in complex with EP-2825 and EP-3945, respectively. The structures reveal distinct agonist binding modes of MRGPRD and large conformational plasticity of the orthosteric pocket. Collectively, the discovery of high-affinity MRGPRD agonists and their distinct binding modes will facilitate the functional study and the structure-based design of ligands targeting this understudied receptor., Competing Interests: Declaration of interests A pending patent application has been filed by Escient Pharmaceuticals that includes compounds EP-2825 and EP-3945. B.L.R. is on the scientific advisory board of Escient Pharmaceuticals., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

In pharmaceutical discovery, the "magic methyl" effect describes a substantial improvement in the pharmacological properties of a drug candidate with the incorporation of methyl groups. Therefore, to expedite the synthesis of methylated drug analogs, late-stage, undirected methylations of C(sp 3 )-H bonds in complex molecules would be valuable. However, current methods for site-selective methylations are limited to activated C(sp 3 )-H bonds. Here we describe a site-selective, undirected methylation of unactivated C(sp 3 )-H bonds, enabled by photochemically activated peroxides and a nickel(II) complex whose turnover is enhanced by an ancillary ligand. The methodology displays compatibility with a wide range of functional groups and a high selectivity for tertiary C-H bonds, making it suitable for the late-stage methylation of complex organic compounds that contain multiple alkyl C-H bonds, such as terpene natural products, peptides, and active pharmaceutical ingredients. Overall, this method provides a synthetic tool to explore the "magic methyl" effect in drug discovery., (© 2024. The Author(s).)

Many neurotransmitter receptors activate G proteins through exchange of GDP for GTP. The intermediate nucleotide-free state has eluded characterization, due largely to its inherent instability. Here we characterize a G protein variant associated with a rare neurological disorder in humans. Gα o K46E has a charge reversal that clashes with the phosphate groups of GDP and GTP. As anticipated, the purified protein binds poorly to guanine nucleotides yet retains wild-type affinity for G protein βγ subunits. In cells with physiological concentrations of nucleotide, Gα o K46E forms a stable complex with receptors and Gβγ, impeding effector activation. Further, we demonstrate that the mutant can be easily purified in complex with dopamine-bound D2 receptors, and use cryo-electron microscopy to determine the structure, including both domains of Gα o , without nucleotide or stabilizing nanobodies. These findings reveal the molecular basis for the first committed step of G protein activation, establish a mechanistic basis for a neurological disorder, provide a simplified strategy to determine receptor-G protein structures, and a method to detect high affinity agonist binding in cells., (© 2024. The Author(s).)

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) continues to be a global threat due to its ability to evolve and generate new subvariants, leading to new waves of infection. Additionally, other coronaviruses like Middle East respiratory syndrome coronavirus (MERS-CoV, formerly known as hCoV-EMC), which first emerged in 2012, persist and continue to present a threat of severe illness to humans. The continued identification of novel coronaviruses, coupled with the potential for genetic recombination between different strains, raises the possibility of new coronavirus clades of global concern emerging. As a result, there is a pressing need for pan-CoV therapeutic drugs and vaccines. After the extensive optimization of an HCV protease inhibitor screening hit, a novel 3CLPro inhibitor (MK-7845) was discovered and subsequently profiled. MK-7845 exhibited nanomolar in vitro potency with broad spectrum activity against a panel of clinical SARS-CoV-2 subvariants and MERS-CoV. Furthermore, when administered orally, MK-7845 demonstrated a notable reduction in viral burdens by >6 log orders in the lungs of transgenic mice infected with SARS-CoV-2 (K18-hACE2 mice) and MERS-CoV (K18-hDDP4 mice).

The phosphate modification of drugs is a common chemical strategy to increase solubility and allow for parenteral administration. Unfortunately, phosphate modifications often elicit treatment- or dose-limiting pruritus through an unknown mechanism. Using unbiased high-throughput drug screens, we identified the Mas-related G protein-coupled receptor X4 (MRGPRX4), a primate-specific, sensory neuron receptor previously implicated in itch, as a potential target for phosphate-modified compounds. Using both G q -mediated calcium mobilization and G protein-independent GPCR assays, we found that phosphate-modified compounds potently activate MRGPRX4. Furthermore, a humanized mouse model expressing MRGPRX4 in sensory neurons exhibited robust phosphomonoester prodrug-evoked itch. To characterize and confirm this interaction, we further determined the structure of MRGPRX4 in complex with a phosphate-modified drug through single-particle cryo-electron microscopy (cryo-EM) and identified critical amino acid residues responsible for the binding of the phosphate group. Together, these findings explain how phosphorylated drugs can elicit treatment-limiting itch and identify MRGPRX4 as a potential therapeutic target to suppress itch and to guide future drug design.

As SARS-CoV-2 continues to circulate, antiviral treatments are needed to complement vaccines. The virus's main protease, 3CLPro, is an attractive drug target in part because it recognizes a unique cleavage site, which features a glutamine residue at the P1 position and is not utilized by human proteases. Herein, we report the invention of MK-7845, a novel reversible covalent 3CLPro inhibitor. While most covalent inhibitors of SARS-CoV-2 3CLPro reported to date contain an amide as a Gln mimic at P1, MK-7845 bears a difluorobutyl substituent at this position. SAR analysis and X-ray crystallographic studies indicate that this group interacts with His163, the same residue that forms a hydrogen bond with the amide substituents typically found at P1. In addition to promising in vivo efficacy and an acceptable projected human dose with unboosted pharmacokinetics, MK-7845 exhibits favorable properties for both solubility and absorption that may be attributable to the unusual difluorobutyl substituent.

Despite the increasing number of GPCR structures and recent advances in peptide design, the development of efficient technologies allowing rational design of high-affinity peptide ligands for single GPCRs remains an unmet challenge. Here, we develop a computational approach for designing conjugates of lariat-shaped macrocyclized peptides and a small molecule opioid ligand. We demonstrate its feasibility by discovering chemical scaffolds for the kappa-opioid receptor (KOR) with desired pharmacological activities. The designed De Novo Cyclic Peptide (DNCP)-β-naloxamine (NalA) exhibit in vitro potent mixed KOR agonism/mu-opioid receptor (MOR) antagonism, nanomolar binding affinity, selectivity, and efficacy bias at KOR. Proof-of-concept in vivo efficacy studies demonstrate that DNCP-β-NalA(1) induces a potent KOR-mediated antinociception in male mice. The high-resolution cryo-EM structure (2.6 Å) of the DNCP-β-NalA-KOR-Gi1 complex and molecular dynamics simulations are harnessed to validate the computational design model. This reveals a network of residues in ECL2/3 and TM6/7 controlling the intrinsic efficacy of KOR. In general, our computational de novo platform overcomes extensive lead optimization encountered in ultra-large library docking and virtual small molecule screening campaigns and offers innovation for GPCR ligand discovery. This may drive the development of next-generation therapeutics for medical applications such as pain conditions., (© 2023. The Author(s).)

Background: Uganda surpasses many African nations and the global average in exclusive breastfeeding (EBF) rates. Yet, malnutrition is a critical issue, with stunting impacting roughly 29% of children under 5 years. Enhancing EBF could mitigate such nutritional challenges. This study focused on determining the current EBF prevalence and identifying associated factors across 77 surveyed districts., Methods: Pooled data from the Lot Quality Assurance Sampling (LQAS) surveys conducted in 77 districts in Uganda during 2021 and 2022 were analyzed. The analysis involved 7,210 mothers of children under 6 months, EBF was considered as the proportion of infants who received breast milk only in the 24 hours before the survey. A mother practicing EBF was (1) currently breastfeeding (2) had not started giving foods other than breastmilk (3) had not given any other probed liquids or (4) semi-solid foods the previous day or night. Multivariable logistic regression was used to identify factors associated with EBF, presenting adjusted odds ratios (aOR) with corresponding 95% confidence intervals at a 5% significance level., Results: The prevalence of EBF was 62.3%. In the adjusted analysis, EBF was more common among older mothers 20-24 years, 25-29 years and 30 + years (aOR 1.4; 95% CI 1.2,1.6), (aOR 1.4; 95% CI 1.1, 1.6) and (aOR 1.3; 95% CI 1.1, 1.5) respectively compared to teenage mothers. Also, EBF was more likely among mothers who lived in rural areas compared to urban areas (aOR 1.1; 95% CI 1.0, 1.3) and those who attended antenatal care (ANC) (aOR 2.2; 95% CI 1.5, 3.1). On the contrary, EBF was less common for children aged 3-5 months compared to younger (aOR 0.5; 95% CI 0.5, 0.6) and children who had received Vitamin A supplementation (aOR 0.7; 95% 0.6, 0.8)., Conclusion: The study suggests that most districts in Uganda might not have made significant strides in improving EBF rates over the last twenty years, pointing to possible ongoing hurdles that need urgent attention. Particularly, there's a pressing need to focus on teenage mothers. Maintaining and strengthening programs that advocate EBF, such as ANC, is crucial to bridge the gaps and bring about more equitable rates among different groups., (© 2023. The Author(s).)

Virtual screening was leveraged to identify novel series of histone deacetylase 6 (HDAC6) inhibitors prior to conducting a high-throughput screen. The virtual screen was designed to augment and expand on chemical matter that would otherwise be unavailable for high-throughput screening. Through this effort we succeeded in identifying four novel, potent and highly selective HDAC6 inhibitor series. These series displayed favorable ligand binding efficiencies and good potential for further optimization. The virtual design specifications and results are discussed herein., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Uganda has made notable progress in improving child nutrition indicators, albeit not fast enough to meet global targets. Navigating the landscape of child nutrition in Uganda demands attention, particularly in light of the necessity for a minimum acceptable diet (MAD) for children aged 12-23 months. While the focus on local nutritional planning is crucial, the absence of routine-specific nutritional status data creates a significant information gap. To bridge this void, this study used datasets from the 2021 Lot Quality Assurance Sampling (LQAS) survey. Data were analysed using multilevel mixed-effects logistic regression (clustering districts based on regional boundaries) at a 5% statistical significance level using STATA version 17. Of the 7,111 children surveyed, 3,256 (49.20%) received the minimum meal frequency, 695 (9.80%) received the minimum dietary diversity, and only 380 (5.34%) received the MAD. There was a notable variation in the proportion of children that received the MAD across regions and districts. Children living in urban areas, children whose mothers had a higher education, and children whose mothers had a diverse diet were more likely to receive the MAD. Children were less likely to receive the MAD if they lived in a household that did not receive a health worker visit within the year. These findings suggest a need to prioritize initiatives aimed at increasing dietary diversity among children in Uganda. This could be done through a variety of approaches, such as leveraging the use of home gardens to boost nutrition through diverse crop cultivation, demonstration gardens, and offering nutrition counselling through village health teams., Competing Interests: The authors have declared that no competing interests exist., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

Background: The initiation and use of family planning (FP) services within the first 12 months following childbirth, postpartum family planning (PPFP), promotes safe motherhood by reducing unintended pregnancies and ensuring appropriate pregnancy spacing. However, there is a paucity of information on PPFP uptake from community surveys. This study aimed to quantify the reported use of PPFP and identify predictors and barriers to PPFP uptake from a large community survey., Methods: We analysed data collected from the 2021 Lot Quality Assurance Sampling (LQAS) survey, a cross-sectional community and household survey that covered 68 districts in Uganda. The survey uses small sample sizes to designate health or administrative geographical areas which are assessed to determine whether they achieved the pre-determined target for defined indicators of interest. We abstracted and analysed data collected from mothers of children aged 12 months or younger on reproductive health and FP. PPFP use was defined as the reported use of modern FP by the mother or their partner. Associations were measured using Pearson's chi-square test at 5% significance. Multivariate logistic regression was performed for variables that were significantly associated with PPFP use to identify the predictors of PPFP., Results: Overall, 8103 mothers of children aged less than 12 years were included in the analysis; the majority of mothers, 55.8% (4521/8103) were above 24 years while 11.7% (950/8103) were 19 years and under. 98% (7942/8103) of the mothers attended at least one antenatal care (ANC) visit and 86.3% (6997/8103) delivered at a health facility. Only 10% (814/8103) of mothers who participated in the survey reported PPFP use at the time of the survey. Reporting of PPFP use was 5 times higher among mothers of children aged 7-12 months (AOR 4.9; 95%CI 4.1-5.8), 50% higher among mothers with secondary education (AOR 1.5; 95%CI 1.0-2.3), 80% higher among breastfeeding mothers (AOR 1.8; 95%CI 1.3-2.4) and 30% lower among those that didn't receive a health worker visit within 3 months preceding the survey (AOR 0.7; 95% CI 0.5-0.8). Among 4.6% (372/8103) who stated a reason for non-use of PPFP, the most cited reasons for not using were breastfeeding 43% (161/372), fear of side effects 26.9% (100/372), respondent/partner opposition 17.6% (48/372) and infrequent sex 12.1% (48/372)., Conclusion: The analysis showed a low proportion of PPFP uptake among mothers of children under 12 years. Possible barriers included child age, education, a health worker visit, and side effects and perceived benefits of possibly improperly implementing lactation amenorrhea method. Integration of social, community and health services could provide a more holistic approach to improving PPFP uptake., (© 2023. BioMed Central Ltd., part of Springer Nature.)

The κ-opioid receptor (KOR) represents a highly desirable therapeutic target for treating not only pain but also addiction and affective disorders 1 . However, the development of KOR analgesics has been hindered by the associated hallucinogenic side effects 2 . The initiation of KOR signalling requires the G i/o -family proteins including the conventional (G i1 , G i2 , G i3 , G oA and G oB ) and nonconventional (G z and G g ) subtypes. How hallucinogens exert their actions through KOR and how KOR determines G-protein subtype selectivity are not well understood. Here we determined the active-state structures of KOR in a complex with multiple G-protein heterotrimers-G i1 , G oA , G z and G g -using cryo-electron microscopy. The KOR-G-protein complexes are bound to hallucinogenic salvinorins or highly selective KOR agonists. Comparisons of these structures reveal molecular determinants critical for KOR-G-protein interactions as well as key elements governing G i/o -family subtype selectivity and KOR ligand selectivity. Furthermore, the four G-protein subtypes display an intrinsically different binding affinity and allosteric activity on agonist binding at KOR. These results provide insights into the actions of opioids and G-protein-coupling specificity at KOR and establish a foundation to examine the therapeutic potential of pathway-selective agonists of KOR., (© 2023. The Author(s).)

The NTSR1 neurotensin receptor (NTSR1) is a G protein-coupled receptor (GPCR) found in the brain and peripheral tissues with neurotensin (NTS) being its endogenous peptide ligand. In the brain, NTS modulates dopamine neuronal activity, induces opioid-independent analgesia, and regulates food intake. Recent studies indicate that biasing NTSR1 toward β-arrestin signaling can attenuate the actions of psychostimulants and other drugs of abuse. Here, we provide the cryoEM structures of NTSR1 ternary complexes with heterotrimeric Gq and GoA with and without the brain-penetrant small-molecule SBI-553. In functional studies, we discovered that SBI-553 displays complex allosteric actions exemplified by negative allosteric modulation for G proteins that are Gα subunit selective and positive allosteric modulation and agonism for β-arrestin translocation at NTSR1. Detailed structural analysis of the allosteric binding site illuminated the structural determinants for biased allosteric modulation of SBI-553 on NTSR1.

The human MAS-related G protein-coupled receptor X1 (MRGPRX1) is preferentially expressed in the small-diameter primary sensory neurons and involved in the mediation of nociception and pruritus. Central activation of MRGPRX1 by the endogenous opioid peptide fragment BAM8-22 and its positive allosteric modulator ML382 has been shown to effectively inhibit persistent pain, making MRGPRX1 a promising target for non-opioid pain treatment. However, the activation mechanism of MRGPRX1 is still largely unknown. Here we report three high-resolution cryogenic electron microscopy structures of MRGPRX1-Gαq in complex with BAM8-22 alone, with BAM8-22 and ML382 simultaneously as well as with a synthetic agonist compound-16. These structures reveal the agonist binding mode for MRGPRX1 and illuminate the structural requirements for positive allosteric modulation. Collectively, our findings provide a molecular understanding of the activation and allosteric modulation of the MRGPRX1 receptor, which could facilitate the structure-based design of non-opioid pain-relieving drugs., (© 2022. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Antiretroviral therapy inhibits HIV-1 replication but is not curative due to establishment of a persistent reservoir after virus integration into the host genome. Reservoir reduction is therefore an important HIV-1 cure strategy. Some HIV-1 nonnucleoside reverse transcriptase inhibitors induce HIV-1 selective cytotoxicity in vitro but require concentrations far exceeding approved dosages. Focusing on this secondary activity, we found bifunctional compounds with HIV-1-infected cell kill potency at clinically achievable concentrations. These targeted activator of cell kill (TACK) molecules bind the reverse transcriptase-p66 domain of monomeric Gag-Pol and act as allosteric modulators to accelerate dimerization, resulting in HIV-1 + cell death through premature intracellular viral protease activation. TACK molecules retain potent antiviral activity and selectively eliminate infected CD4 + T cells isolated from people living with HIV-1, supporting an immune-independent clearance strategy.

Reactive oxygen species (ROS) are oxygen derivatives that arise intrinsically from the oxidative phosphorylation process and extrinsically as a response to xenobiotics and pollution. ROS is involved in various conditions such as exercise, aging, inflammation, and neurodegenerative diseases. In the aging process, increased cellular senescence and decreased endogenous antioxidants also occur. Meanwhile, physical activity, specifically exercise, can modulate ROS. The impact of exercise on ROS varies from harmful to beneficial and depends on the type of exercise as they induce different types of ROS. Long-term exercise regulates signaling pathways that enhance antioxidant defense systems and control ROS production. This review will discuss studies on how exercise can regulate ROS and which type of exercise has a role in delaying the aging process. This review also exposes the impact of nutraceutical antioxidant agents that likely enhance the benefit of exercise. The nutraceutical antioxidants agents that likely enhance the benefit of exercise are creatine, whey, and ascorbic acid. Exercise is rewarding for the aging population concerning increasing their quality of life. Special consideration to exercise needs to be given to the type of exercise, and the exercise must be done continuously., Competing Interests: The authors declare that no conflict of interests exists., (© Copyright by the Author(s). Published by Cell Physiol Biochem Press.)

Designer receptors exclusively activated by designer drugs (DREADDs) represent a powerful chemogenetic technology for the remote control of neuronal activity and cellular signalling 1-4 . The muscarinic receptor-based DREADDs are the most widely used chemogenetic tools in neuroscience research. The G q -coupled DREADD (hM3Dq) is used to enhance neuronal activity, whereas the G i/o -coupled DREADD (hM4Di) is utilized to inhibit neuronal activity 5 . Here we report four DREADD-related cryogenic electron microscopy high-resolution structures: a hM3Dq-miniG q complex and a hM4Di-miniG o complex bound to deschloroclozapine; a hM3Dq-miniG q complex bound to clozapine-N-oxide; and a hM3R-miniG q complex bound to iperoxo. Complemented with mutagenesis, functional and computational simulation data, our structures reveal key details of the recognition of DREADD chemogenetic actuators and the molecular basis for activation. These findings should accelerate the structure-guided discovery of next-generation chemogenetic tools., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Serotonin (5-hydroxytryptamine [5-HT]) 5-HT2-family receptors represent essential targets for lysergic acid diethylamide (LSD) and all other psychedelic drugs. Although the primary psychedelic drug effects are mediated by the 5-HT 2A serotonin receptor (HTR2A), the 5-HT 2B serotonin receptor (HTR2B) has been used as a model receptor to study the activation mechanisms of psychedelic drugs due to its high expression and similarity to HTR2A. In this study, we determined the cryo-EM structures of LSD-bound HTR2B in the transducer-free, Gq-protein-coupled, and β-arrestin-1-coupled states. These structures provide distinct signaling snapshots of LSD's action, ranging from the transducer-free, partially active state to the transducer-coupled, fully active states. Insights from this study will both provide comprehensive molecular insights into the signaling mechanisms of the prototypical psychedelic LSD and accelerate the discovery of novel psychedelic drugs., Competing Interests: Declaration of interests The Krogan Laboratory has received research support from Vir Biotechnology, F. Hoffmann-La Roche, and Rezo Therapeutics. N.J.K. has financially compensated consulting agreements with the Icahn School of Medicine at Mount Sinai, New York; Maze Therapeutics; Interline Therapeutics; Rezo Therapeutics; GEn1E Life Sciences, Inc.; and Twist Bioscience Corp. N.J.K. is on the Board of Directors of Rezo Therapeutics and is a shareholder in Tenaya Therapeutics, Maze Therapeutics, Rezo Therapeutics, and Interline Therapeutics. G.S. is co-founder and consultant for Deep Apple Therapeutics., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Although current antiretroviral therapy can control HIV-1 replication and prevent disease progression, it is not curative. Identifying mechanisms that can lead to eradication of persistent viral reservoirs in people living with HIV-1 (PLWH) remains an outstanding challenge to achieving cure. Utilizing a phenotypic screen, we identified a novel chemical class capable of killing HIV-1 infected peripheral blood mononuclear cells. Tool compounds ICeD-1 and ICeD-2 (" i nducer of ce ll d eath-1 and 2"), optimized for potency and selectivity from screening hits, were used to deconvolute the mechanism of action using a combination of chemoproteomic, biochemical, pharmacological, and genetic approaches. We determined that these compounds function by modulating dipeptidyl peptidase 9 (DPP9) and activating the caspase recruitment domain family member 8 (CARD8) inflammasome. Efficacy of ICeD-1 and ICeD-2 was dependent on HIV-1 protease activity and synergistic with efavirenz, which promotes premature activation of HIV-1 protease at high concentrations in infected cells. This in vitro synergy lowers the efficacious cell kill concentration of efavirenz to a clinically relevant dose at concentrations of ICeD-1 or ICeD-2 that do not result in complete DPP9 inhibition. These results suggest engagement of the pyroptotic pathway as a potential approach to eliminate HIV-1 infected cells.

Cystic fibrosis transmembrane regulator (CFTR) is a dynamic membrane protein belonging to the ABC transporter family. It is unusual within this family as it is an ion channel, as opposed to a transporter. Activation of CFTR requires ATP and phosphorylation by PKA, and dysregulation of CFTR mediated salt and water homeostasis can lead to cystic fibrosis. Recent advancements in structural biological methods have led to more than 10 published CFTR structures, and, so far, all of these structures of CFTR, determined by cryo-EM, have been limited to detergent-purified protein preparations. To visualize CFTR in an environment that more closely represents its native membranous environment, we utilized two different lipoprotein particle encapsulation techniques: one in which the ion channel is first purified and then reconstituted using the membrane scaffolding protein Saposin A and another that uses the solubilizing polymer Sokalan CP9 (DIBMA) to extract CFTR directly from membranes. Structures derived from these types of preparations may better correlate to their function, for instance, the single-channel measurements from membrane vesicles.

RNA editing is a process by which post-transcriptional changes of mRNA nucleotides alter protein function through modification of the amino acid content. The 5HT 2C serotonin receptor, which undergoes 32 distinct RNA-editing events leading to 24 protein isoforms, is a notable example of this process. These 5HT 2C isoforms display differences in constitutive activity, agonist/inverse agonist potencies, and efficacies. To elucidate the molecular mechanisms responsible for these effects of RNA editing, we present four active-state 5HT 2C -transducer-coupled structures of three representative isoforms (INI, VGV, and VSV) with the selective drug lorcaserin (Belviq) and the classic psychedelic psilocin. We also provide a comprehensive analysis of agonist activation and constitutive activity across all 24 protein isoforms. Collectively, these findings reveal a unique hydrogen-bonding network located on intracellular loop 2 that is subject to RNA editing, which differentially affects GPCR constitutive and agonist signaling activities., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Serotonin receptors are important targets for established therapeutics and drug development as they are expressed throughout the human body and play key roles in cell signaling. There are 12 serotonergic G protein-coupled receptor members encoded in the human genome, of which the 5-hydroxytryptamine (5-HT) 5A receptor (5-HT 5A R) is the least understood and lacks selective tool compounds. Here, we report four high-resolution (2.73-2.80 Å) structures of human 5-HT 5A Rs, including an inactive state structure bound to an antagonist AS2674723 by crystallization and active state structures bound to a partial agonist lisuride and two full agonists, 5-carboxamidotryptamine (5-CT) and methylergometrine, by cryo-EM. Leveraging the new structures, we developed a highly selective and potent antagonist for 5-HT 5A R. Collectively, these findings both enhance our understanding of this enigmatic receptor and provide a roadmap for structure-based drug discovery for 5-HT 5A R., (© 2022. The Author(s), under exclusive licence to Springer Nature America, Inc.)

The 1,1,2,2-tetrafluoroethylene unit is prevalent in bioactive molecules and functional materials. Despite being in principle a straightforward strategy to access this motif, the direct tetrafluorination of alkynes involves very hazardous or inconvenient reagents. Therefore, safer and convenient alternatives are sought after. We developed a mild and operationally simple perfluorination method converting 1-alkynyl triazenes into 1,1,2,2-tetrafluoro alkyl triazenes, employing cheap and readily accessible reagents. Moreover, a judicious tuning of the reaction conditions enables access to α-difluoro triazenyl ketones. Complementary, electrophilic fluorination of alkynyl triazenes gives rise to the regioisomeric α-difluoro acyl triazenes. These three chemo- and regio-divergent protocols enable access to elusive fluorinated 1-alkyl and 1-acyl triazenes, thus expanding the chemical space for these unusual entities. Furthermore, several reaction intermediates and side products revealed insights on the reaction pathways that may be useful for further fluorination chemistry of alkynes., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Limitations to successful single-particle cryo-electron microscopy (cryo-EM) projects include stable sample generation, production of quality cryo-EM grids with randomly oriented particles embedded in thin vitreous ice and access to microscope time. To address the limitation of microscope time, methodologies to more efficiently collect data on a 200 keV Talos Arctica cryo-transmission electron microscope at speeds as fast as 720 movies per hour (∼17 000 per day) were tested. In this study, key parameters were explored to increase data collection speed including: (1) using the beam-image shift method to acquire multiple images per stage position, (2) employing UltrAufoil TEM grids with R0.6/1 hole spacing, (3) collecting hardware-binned data and (4) adjusting the image shift delay factor in SerialEM . Here, eight EM maps of mouse apoferritin at 1.8-1.9 Å resolution were obtained in the analysis with data collection times for each dataset ranging from 56 min to 2 h. An EM map of mouse apoferritin at 1.78 Å was obtained from an overnight data collection at a speed of 500 movies per hour and subgroup analysis performed, with no significant variation observed in data quality by image shift distance and image shift delay. The findings and operating procedures detailed herein allow for rapid turnover of single-particle cryo-EM structure determination., (© Peck, Fay and Strauss 2022.)

The MRGPRX family of receptors (MRGPRX1-4) is a family of mas-related G-protein-coupled receptors that have evolved relatively recently 1 . Of these, MRGPRX2 and MRGPRX4 are key physiological and pathological mediators of itch and related mast cell-mediated hypersensitivity reactions 2-5 . MRGPRX2 couples to both G i and G q in mast cells 6 . Here we describe agonist-stabilized structures of MRGPRX2 coupled to G i1 and G q in ternary complexes with the endogenous peptide cortistatin-14 and with a synthetic agonist probe, respectively, and the development of potent antagonist probes for MRGPRX2. We also describe a specific MRGPRX4 agonist and the structure of this agonist in a complex with MRGPRX4 and G q . Together, these findings should accelerate the structure-guided discovery of therapeutic agents for pain, itch and mast cell-mediated hypersensitivity., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

The 2-pyrone motif occurs frequently in bioactive natural products and is appreciated as synthetic intermediates. However, only few methods allow for diversifying functional group modifications on this relevant heterocycle. The distinct properties of 1-alkynyl triazenes promote a smooth addition of propiolic acids across the triple bond. Addition of catalytic amounts of silver salt induces cyclization to 2-pyrones. Depending on the reaction temperature, either 6-triazenyl or 5-triazenyl 2-pyrones are selectively formed. The triazenyl unit is subsequently replaced by a variety of valuable groups in a one-pot process yielding for instance 2-fluoro pyrones. The substitution occurs with an intriguing 1,5-carbonyl transposition. Moreover, the triazenyl group serves as traceless activating group for subsequent Diels-Alder cycloadditions and as a constituting unit for rare fused aminopyrazole pyrone heterocycles., Competing Interests: The authors declare no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

The development of catalytic enantioselective transformations, enabling the construction of complex molecular scaffolds from simple precursors, has been a long-standing challenge in organic synthesis. Recent achievements in transition-metal catalyzed enantioselective functionalizations of carbon-hydrogen (C-H) bonds represent a promising pathway toward this goal. Over the last two decades, iridium catalysis has evolved as a valuable tool enabling the stereocontrolled synthesis of chiral molecules via C-H activation. The development of iridium-based systems with various chiral ligand classes, as well as studies of their reaction mechanisms, has resulted in dynamic progress in this area. This review aims to present a comprehensive picture of the enantioselective functionalizations of C-H bonds by chiral iridium complexes with emphasis on the mechanisms of the C-H activation step.

Densely substituted fused aromatic triazenes can be prepared by [2 + 2 + 2] cyclotrimerization reactions of 1-alkynyl triazenes. The Cp*Ru-catalyzed cyclization proceeds well with both simple alkynyl triazenes and tethered 1-diynyl triazenes. Attractively, the methodology can be extended to pyridine synthesis by replacing an alkyne with a nitrile. The reaction is regioselective and yields the sterically more hindered product. The triazene group precisely installed on the synthesized aryl and pyridyl ring is a highly versatile moiety, which is effortlessly converted into the most important and frequently used functional aryl substituents, including fluorides. It is also suited for intramolecular transformations to afford a variety of valuable heterocycles. The coordination chemistry of alkynyl triazenes and Cp*RuCl was studied and led to the structural characterization of a Cp*RuCl(η 2 -alkyne) complex, a Cp*RuCl(η 4 -cyclobutadiene) complex, and an unusual dinuclear Ru complex with a bridging tetramethylfulvene ligand. Complexes of this type are potentially involved in catalyst deactivation pathways.

The cystic fibrosis transmembrane conductance regulator (CFTR) anion channel, crucial to epithelial salt and water homeostasis, and defective due to mutations in its gene in patients with cystic fibrosis, is a unique member of the large family of ATP-binding cassette transport proteins. Regulation of CFTR channel activity is stringently controlled by phosphorylation and nucleotide binding. Structural changes that underlie transitions between active and inactive functional states are not yet fully understood. Indeed the first 3D structures of dephosphorylated, ATP-free, and phosphorylated ATP-bound states were only recently reported. Here we have determined the structure of inactive and active states of a thermally stabilized CFTR, the latter with a very high channel open probability, confirmed after reconstitution into proteoliposomes. These structures, obtained at nominal resolution of 4.3 and 6.6 Å, reveal a unique repositioning of the transmembrane helices and regulatory domain density that provide insights into the structural transition between active and inactive functional states of CFTR. Moreover, we observe an extracellular vestibule that may provide anion access to the pore due to the conformation of transmembrane helices 7 and 8 that differs from the previous orthologue CFTR structures. In conclusion, our work contributes detailed structural information on an active, open state of the CFTR anion channel.

The application of magnification devices in endodontics is mainly meant for visual enhancement and improved ergonomics. This is crucial especially when long hours are spent in a narrow operating space to treat obscure microanatomy. Nevertheless, application of magnification in endodontics has yet to be introduced into the mainstream practice due to various influences in behavioral patterns. By conducting an extensive literature search in the PubMed database, this narrative review paper depicts the present state of magnification devices, their applications within the endodontic practice, factors that influence their usage, the advantages, and shortcomings, as well as the significances of magnification in the field of endodontics. This review paper will encourage clinicians to employ magnification in their practice for improved outcome., Competing Interests: There are no conflicts of interest.

Objective: To assess variability in the use of surgical sterilization among privately insured U.S. men and women., Study Design: We queried the MarketScan Commercial Claims database using CPT, ICD9, and HCPCS codes to identify 658,509 individuals between 18-65 years old (0.37% of total) who underwent male or female sterilization between 2009-2014. We examined annual trends using Cochran-Mantel-Haenszel test. We analyzed differences in age, geographic distribution, and family size using Wilcoxon sum-rank and generalized chi-squared tests., Results: Between 2009-2014, 422,290 men (0.55% of total men) and 236,219 women (0.24% of total women) with employer-sponsored insurance underwent male and female sterilization, respectively. Annual male sterilizations decreased from 77,565 (0.60%) in 2009 to 61,436 (0.51%) in 2014 (p<.001), while annual female sterilizations decreased from 43,766 (0.26%) to 30,465 (0.19%) (p<.001) over the same time period. Median age at time of male or female sterilization was 38 and 37 years, respectively. The decision to undergo sterilization at age 35 or older was associated with family size of 4 or more individuals (p<.001). Sterilization was more common in urban areas, with 84% of male sterilizations and 79% of female sterilizations performed in urban areas. 79% of men compared to 60% of women who underwent sterilization were the primary policyholders of their employer-sponsored healthcare plans (p<.001)., Conclusion: Male sterilization was twice as common as female sterilization in this privately insured cohort. Use of surgical sterilization was associated with increased age and larger family size. There was a decline in the annual number of male and female sterilizations during the study period., Implications: Male sterilization is more common among US men with employer-based insurance than among the general population. The decline in sterilization may reflect cultural factors and the rise of long-acting reversible contraception. Analyzing the sociodemographic factors impacting sterilization may provide insight into contraceptive choice and improve reproductive health services., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The cystic fibrosis transmembrane conductance regulator (CFTR) is an asymmetric ATP-binding cassette transporter in which ATP hydrolysis occurs only at the second of the two composite nucleotide-binding sites whereas there are noncanonical substitutions of key catalytic residues in the first site. Therefore, in widely accepted models of CFTR function, ATP is depicted as remaining bound at the first site while it is hydrolyzed at the second site. However, the long lifetime of ATP at nucleotide-binding domain 1 (NBD1) had been measured under conditions where the channel had not been activated by phosphorylation. Here we show that phosphorylation by protein kinase A (PKA), obligatory for channel activation, strongly accelerates dissociation of the unhydrolyzed ATP from NBD1 of both full-length and NBD2-deleted CFTR. This stimulation of nucleotide release results from phosphorylation of the CFTR regulatory domain (residues 634-835) (R-domain). Mimicking phosphorylation by mutating the eight phosphorylation sites in the R-domain (8SE) has the same robust effect on accelerating the dissociation of ATP from NBD1. These findings provide new insight into relationships between R-domain phosphorylation and ATP binding and hydrolysis, the two main CFTR regulatory pathways.

G-protein-coupled receptors (GPCRs) control vital cellular signaling pathways. GPCR oligomerization is proposed to increase signaling diversity. However, many reports have arrived at disparate conclusions regarding the existence, stability, and stoichiometry of GPCR oligomers, partly because of cellular complexity and ensemble averaging of intrareconstitution heterogeneities that complicate the interpretation of oligomerization data. To overcome these limitations, we exploited fluorescence-microscopy-based high-content analysis of single proteoliposomes. This allowed multidimensional quantification of intrinsic monomer-monomer interactions of three class A GPCRs (β 2 -adrenergic receptor, cannabinoid receptor type 1, and opsin). Using a billion-fold less protein than conventional assays, we quantified oligomer stoichiometries, association constants, and the influence of two ligands and membrane curvature on oligomerization, revealing key similarities and differences for three GPCRs with decidedly different physiological functions. The assays introduced here will assist with the quantitative experimental observation of oligomerization for transmembrane proteins in general., (Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.)

Using the HIV-1 protease binding mode of MK-8718 and PL-100 as inspiration, a novel aspartate binding bicyclic piperazine sulfonamide core was designed and synthesized. The resulting HIV-1 protease inhibitor containing this core showed an 60-fold increase in enzyme binding affinity and a 10-fold increase in antiviral activity relative to MK-8718 ., Competing Interests: The authors declare no competing financial interest.

Objective: To describe the relationship between severe diminished ovarian reserve (DOR) and assisted reproductive technology outcomes., Study Design: Retrospective cohort including all United States’ fertility centers reporting to the CDC National ART Surveillance System, 2004–2012. Among women aged <41 (504,266 fresh autologous IVF cycles), we calculated cancellation rate/cycle and pregnancy rate/transfer, stratified by age, by maximum follicle-stimulating hormone (FSH). Cancellation rate per cycle and pregnancy, live birth, and miscarriage rates per transfer were compared among women with and without DOR. We used multivariable log binomial regression, stratified by age, to calculate adjusted relative risk (aRR) for the association between DOR and these outcomes and, within DOR groups, between stimulation type and outcomes., Results: Cancellation rate/cycle increased with increasing FSH and with DOR severity. For women aged <35 who underwent transfer, aRR for pregnancy and live birth indicated slightly reduced likelihood of these outcomes (severe vs. no DOR); confidence intervals approached the null. Among women with severe DOR, stimulation type was not associated with likelihood of pregnancy or live birth per transfer in any group except women ages 38–40., Conclusion: Women with severe DOR are at significantly increased risk of cancellation; however, those who undergo transfer have pregnancy and live birth chances similar to those of women without DOR after controlling for cycle characteristics.

K ATP channels are metabolic sensors that couple cell energetics to membrane excitability. In pancreatic β-cells, channels formed by SUR1 and Kir6.2 regulate insulin secretion and are the targets of antidiabetic sulfonylureas. Here, we used cryo-EM to elucidate structural basis of channel assembly and gating. The structure, determined in the presence of ATP and the sulfonylurea glibenclamide, at ~6 Å resolution reveals a closed Kir6.2 tetrameric core with four peripheral SUR1s each anchored to a Kir6.2 by its N-terminal transmembrane domain (TMD0). Intricate interactions between TMD0, the loop following TMD0, and Kir6.2 near the proposed PIP 2 binding site, and where ATP density is observed, suggest SUR1 may contribute to ATP and PIP 2 binding to enhance Kir6.2 sensitivity to both. The SUR1-ABC core is found in an unusual inward-facing conformation whereby the two nucleotide binding domains are misaligned along a two-fold symmetry axis, revealing a possible mechanism by which glibenclamide inhibits channel activity.

The human cannabinoid receptor, CB 1 , has been difficult to purify in a functional form, hampering structural and biophysical studies. Here, we present our approaches for obtaining pure, detergent solubilized, functional CB 1 . We also discuss our site-directed fluorescence labeling (SDFL) methods for identifying different structural changes that CB 1 can undergo upon binding different cannabinoid ligands. To identify optimal CB 1 constructs for these studies (those with the best expression levels, solubility in detergent and function), we first screened various CB 1 -green fluorescent protein chimeras in a mammalian expression system. Once identified, we then tagged the best candidates with the 1D4 epitope (the C-terminus of rhodopsin) and purified them using a single-step immunoaffinity process. The resulting, highly pure proteins retain their ability to activate G-protein, and are ~85% functional, as assessed by radioligand binding studies. The SDFL studies involve introducing single cysteine residues at key places in the receptor, then labeling them with a small fluorophore, bimane. The spectral properties of the bimane probe are then monitored before and after addition of cannabinoid ligands. Changes in fluorescence of the attached probe indicate regions of the receptor undergoing conformational changes upon ligand binding. Together, these approaches set the stage for a deeper understanding of the structure and function of CB 1 . Access to pure, functional CB 1 makes subsequent structural studies possible (such as crystallography and single-particle EM analysis), and the SDFL studies enable a better structural and mechanistic understanding of this key receptor and the dynamic changes it undergoes during activation and attenuation., (© 2017 Elsevier Inc. All rights reserved.)

Here, we describe two insights into the role of receptor conformational dynamics during agonist release (all-trans retinal, ATR) from the visual G protein-coupled receptor (GPCR) rhodopsin. First, we show that, after light activation, ATR can continually release and rebind to any receptor remaining in an active-like conformation. As with other GPCRs, we observe that this equilibrium can be shifted by either promoting the active-like population or increasing the agonist concentration. Second, we find that during decay of the signaling state an active-like, yet empty, receptor conformation can transiently persist after retinal release, before the receptor ultimately collapses into an inactive conformation. The latter conclusion is based on time-resolved, site-directed fluorescence labeling experiments that show a small, but reproducible, lag between the retinal leaving the protein and return of transmembrane helix 6 (TM6) to the inactive conformation, as determined from tryptophan-induced quenching studies. Accelerating Schiff base hydrolysis and subsequent ATR dissociation, either by addition of hydroxylamine or introduction of mutations, further increased the time lag between ATR release and TM6 movement. These observations show that rhodopsin can bind its agonist in equilibrium like a traditional GPCR, provide evidence that an active GPCR conformation can persist even after agonist release, and raise the possibility of targeting this key photoreceptor protein by traditional pharmaceutical-based treatments., Competing Interests: The authors declare no conflict of interest.

Over the past year, the Zika virus, an arthropod-borne Flavivirus , has transitioned from a relatively unknown tropical disease to the cause of a public health emergency. The Zika virus is transmitted by the Aedes species of mosquito as well as by sexual intercourse. Although the symptoms of acute Zika virus infection are usually mild and self-limited, it causes fetal microcephaly in pregnant women, and is associated with an increased risk of Guillain-Barré syndrome. The risk of microcephaly from Zika virus infection is estimated to be highest in women who are infected during the first trimester of pregnancy. The Zika virus has been shown to have significant neurotrophism in vivo and in vitro , although further study is needed to characterize its mechanisms of pathogenesis. Zika virus has previously caused two known outbreaks in the Pacific region prior to the current epidemic in South and Central America, and the current epidemic has affected at least 440,000 to 1,300,000 people. The population of the vector for the current epidemic, Aedes aegypti , varies seasonally in the United States, however there have been few documented cases of local spread of the Zika infection in the United States and it is unclear whether epidemic spread of Zika will occur within the United States., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

A novel HIV protease inhibitor was designed using a morpholine core as the aspartate binding group. Analysis of the crystal structure of the initial lead bound to HIV protease enabled optimization of enzyme potency and antiviral activity. This afforded a series of potent orally bioavailable inhibitors of which MK-8718 was identified as a compound with a favorable overall profile.

G protein-coupled receptors (GPCRs) are surprisingly flexible molecules that can do much more than simply turn on G proteins. Some even exhibit biased signaling, wherein the same receptor preferentially activates different G-protein or arrestin signaling pathways depending on the type of ligand bound. Why this behavior occurs is still unclear, but it can happen with both traditional ligands and ligands that bind allosterically outside the orthosteric receptor binding pocket. Here, we looked for structural mechanisms underlying these phenomena in the marijuana receptor CB1. Our work focused on the allosteric ligand Org 27569, which has an unusual effect on CB1-it simultaneously increases agonist binding, decreases G--protein activation, and induces biased signaling. Using classical pharmacological binding studies, we find that Org 27569 binds to a unique allosteric site on CB1 and show that it can act alone (without need for agonist cobinding). Through mutagenesis studies, we find that the ability of Org 27569 to bind is related to how much receptor is in an active conformation that can couple with G protein. Using these data, we estimated the energy differences between the inactive and active states. Finally, site-directed fluorescence labeling studies show the CB1 structure stabilized by Org 27569 is different and unique from that stabilized by antagonist or agonist. Specifically, transmembrane helix 6 (TM6) movements associated with G-protein activation are blocked, but at the same time, helix 8/TM7 movements are enhanced, suggesting a possible mechanism for the ability of Org 27569 to induce biased signaling.

Insulin-like growth factor plays a paracrine/autocrine role in regulating testicular function in the stallion, but its presence in the equine epididymis remains unknown. The aim of this study was to test the hypothesis that insulin-like growth factor-I (IGF-I) and IGF-I receptor (IGF-IR) are localized in the caput, corpus, and cauda of the epididymis in an age-dependent manner. Immediately after castration, epididymal tissue was fixed, paraffin-embedded, and processed for immunohistochemistry (IHC). Western blot was also performed using equine epididymal extracts to verify the specificity of the antibodies against IGF-I and IGF-IR. Immunolabeling of IGF-I was observed in the cytoplasm of principal and basal cells in the caput, corpus, and cauda at the pre-pubertal (3-7 months), pubertal (12-18 months), post-pubertal (2-4 years), and adult stages (4.5-8 years). Immunolabeling of IGF-IR was observed in the cytoplasm of principal cells in all regions of the epididymis in each age group. Immunolabeling of IGF-IR was also detected in the cytoplasm of basal cells from animals of all ages. Bands observed by Western blot corresponded to the molecular weights of IGF-I and IGF-IR, ~23 kDa and 95 kDa, respectively. These results suggest that IGF-I might function as an autocrine and/or paracrine factor during the development, maintenance and/or secretions of the stallion epididymis.

Background: The lifetime cost of a child with an orofacial cleft is estimated at $101,000, which amounts to $697 million total for those born each year with orofacial clefts. There has been a trend toward outpatient procedures for cleft lip repair (CLR) and alveolar bone grafting (ABG), and studies have shown no disparities in safety or outcome between inpatient and ambulatory treatment. The financial implications of outpatient versus inpatient procedures have not been compared., Methods: Financial data were collected for outpatient (n = 33) and inpatient (n = 2) CLR, as well as outpatient (n = 7) and inpatient (n = 5) ABG during a 5-year period at our institution. We examined hospital charges and reimbursement for these procedures by private insurance plans and Medicaid Managed Care (MMC) plans., Results: The average total reimbursements for inpatient and outpatient CLR were similar at $6848 and $5557, respectively. Average facility reimbursement for CLR was greater for inpatient ($5344) than outpatient ($4291) procedures. Average professional reimbursement was similar between inpatient ($1504) and outpatient ($1266) CLR.For ABG, the average total inpatient reimbursement was $14,573, whereas outpatient was $8877. Average facility reimbursements were greater for inpatient ($12,398) than outpatient ($7183) ABG. Average professional reimbursement was similar between inpatient ($2175) and outpatient ($1693) ABG, with 35% and 31% of charges reimbursed, respectively.A substantial difference existed between reimbursements based on insurance types for both outpatient CLR and outpatient ABG. On average for CLR, commercial payers reimbursed 52% ($7344) of overall charges, whereas Medicaid and MMC reimbursed 9% ($1447). For ABG, commercial payers reimbursed an average of 78% ($11,950) of overall charges, whereas Medicaid and MMC reimbursed 10% ($1192)., Conclusions: Fewer patients' insurance companies are reimbursing for inpatient stays; in many cases, even patients who remain hospitalized up to 48 hours are treated as "day surgery" from a reimbursement perspective. For outpatient surgery, a greater percentage of CLR and ABG charges were successfully recouped compared to inpatient surgery. Awareness of higher payment for inpatient surgery and potential savings through use of the outpatient setting is crucial for hospitals and the US health care system as a whole.

Proteoliposome reconstitution is a standard method to stabilize purified transmembrane proteins in membranes for structural and functional assays. Here we quantified intrareconstitution heterogeneities in single proteoliposomes using fluorescence microscopy. Our results suggest that compositional heterogeneities can severely skew ensemble-average proteoliposome measurements but also enable ultraminiaturized high-content screens. We took advantage of this screening capability to map the oligomerization energy of the β2-adrenergic receptor using ∼10(9)-fold less protein than conventional assays.

Various studies have implicated the concave surface of arrestin in the binding of the cytosolic surface of rhodopsin. However, specific sites of contact between the two proteins have not previously been defined in detail. Here, we report that arrestin shares part of the same binding site on rhodopsin as does the transducin Gα subunit C-terminal tail, suggesting binding of both proteins to rhodopsin may share some similar underlying mechanisms. We also identify two areas of contact between the proteins near this region. Both sites lie in the arrestin N-domain, one in the so-called "finger" loop (residues 67-79) and the other in the 160 loop (residues 155-165). We mapped these sites using a novel tryptophan-induced quenching method, in which we introduced Trp residues into arrestin and measured their ability to quench the fluorescence of bimane probes attached to cysteine residues on TM6 of rhodopsin (T242C and T243C). The involvement of finger loop binding to rhodopsin was expected, but the evidence of the arrestin 160 loop contacting rhodopsin was not. Remarkably, our data indicate one site on rhodopsin can interact with multiple structurally separate sites on arrestin that are almost 30 Å apart. Although this observation at first seems paradoxical, in fact, it provides strong support for recent hypotheses that structural plasticity and conformational changes are involved in the arrestin-rhodopsin binding interface and that the two proteins may be able to interact through multiple docking modes, with arrestin binding to both monomeric and dimeric rhodopsin.

The human cannabinoid receptor, CB1, a G protein-coupled receptor (GPCR), contains a relatively long (∼110 a.a.) amino terminus, whose function is still not defined. Here we explore a potential role for the CB1 N-terminus in modulating ligand binding to the receptor. Although most of the CB1 N-terminus is not necessary for ligand binding, previous studies have found that mutations introduced into its conserved membrane proximal region (MPR) do impair the receptors ability to bind ligand. Moreover, within the highly conserved MPR (∼ residues 90-110) lie two cysteine residues that are invariant in all CB1 receptors. We find these two cysteines (C98 and C107) form a disulfide in heterologously expressed human CB1, and this C98-C107 disulfide is much more accessible to reducing agents than the previously known disulfide in extracellular loop 2 (EL2). Interestingly, the presence of the C98-C107 disulfide modulates ligand binding to the receptor in a way that can be quantitatively analyzed by an allosteric model. The C98-C107 disulfide also alters the effects of allosteric ligands for CB1, Org 27569 and PSNCBAM-1. Together, these results provide new insights into how the N-terminal MPR and EL2 act together to influence the high-affinity orthosteric ligand binding site in CB1 and suggest that the CB1 N-terminal MPR may be an area through which allosteric modulators can act.

Aim: To establish the range of normal stereoacuity thresholds and evaluate the diagnostic reliability of stereoacuity tests in preschool-aged children., Methods: 1606 children, aged 24-72 months, had detailed eye examinations and stereoacuity testing. Lang-Stereotest II (LangII) was attempted on all children, Stereo Smile Stereoacuity II Test (SSST) was conducted on children aged < 30 months and on older children who could not complete the Randot Preschool Stereoacuity Test (RPST). The RPST was conducted on children aged ≥ 30 months and on some younger children who passed both the LangII and SSST., Results: Modes for the age groups 24-47 months and 48-72 months were: 200 arcsec for both age groups with the LangII test; 120 arcsec and 60 arcsec, respectively, with the SSST; 100 arcsec and 60 arcsec, respectively, with the RPST. Age-adjusted areas under the curve for detecting amblyopia, strabismus and anisometropia were: for the LangII test, 0.72, 0.68 and 0.60, respectively; for the SSST, 0.73, 0.80 and 0.57, respectively; for the RPST, 0.92, 0.82 and 0.73, respectively., Conclusions: Normative data for the LangII, RPST and SSST stereoacuity tests were determined for children aged 24-72 months. Sensitivity and specificity at individual disparity levels for detecting anisometropia, amblyopia and strabismus were also determined for RPST and SSST. Using area under age-adjusted receiver operating curves, the RPST was found to be the most reliable in detecting ocular conditions compared with the LangII and SSST tests.

Allosteric ligands that modulate how G protein-coupled receptors respond to traditional orthosteric drugs are an exciting and rapidly expanding field of pharmacology. An allosteric ligand for the cannabinoid receptor CB1, Org 27569, exhibits an intriguing effect; it increases agonist binding, yet blocks agonist-induced CB1 signaling. Here we explored the mechanism behind this behavior, using a site-directed fluorescence labeling approach. Our results show that Org 27569 blocks conformational changes in CB1 that accompany G protein binding and/or activation, and thus inhibit formation of a fully active CB1 structure. The underlying mechanism behind this behavior is that simultaneous binding of Org 27569 produces a unique agonist-bound conformation, one that may resemble an intermediate structure formed on the pathway to full receptor activation.