Constrained catecholamines gain ß2AR selectivity through allosteric effects on pocket dynamics.

G protein-coupled receptors (GPCRs) within the same subfamily often share high homology in their orthosteric pocket and therefore pose challenges to drug development. The amino acids that form the orthosteric binding pocket for epinephrine and norepinephrine in the ß1 and ß2 adrenergic receptors (ß1AR and ß2AR) are identical. Here, to examine the effect of conformational restriction on ligand binding kinetics, we synthesized a constrained form of epinephrine. Surprisingly, the constrained epinephrine exhibits over 100-fold selectivity for the ß2AR over the ß1AR. We provide evidence that the selectivity may be due to reduced ligand flexibility that enhances the association rate for the ß2AR, as well as a less stable binding pocket for constrained epinephrine in the ß1AR. The differences in the amino acid sequence of the extracellular vestibule of the ß1AR allosterically alter the shape and stability of the binding pocket, resulting in a marked difference in affinity compared to the ß2AR. These studies suggest that for receptors containing identical binding pocket residues, the binding selectivity may be influenced in an allosteric manner by surrounding residues, like those of the extracellular loops (ECLs) that form the vestibule. Exploiting these allosteric influences may facilitate the development of more subtype-selective ligands for GPCRs.

Developmental Monitoring and Referral for Low-Income Children Served by WIC: Program Development and Implementation Outcomes.

OBJECTIVE: To develop, implement, and assess implementation outcomes for a developmental monitoring and referral program for children in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). METHODS: Based on Centers for Disease Control and Prevention's Learn the Signs. Act Early. campaign, the program was developed and replicated in two phases at 20 demographically diverse WIC clinics in eastern Missouri. Parents were asked to complete developmental milestone checklists for their children, ages 2 months to 4 years, during WIC eligibility recertification visits; WIC staff referred children with potential concerns to their healthcare providers for developmental screening. WIC staff surveys and focus groups were used to assess initial implementation outcomes. RESULTS: In both phases, all surveyed staff (n = 46) agreed the program was easy to use. Most (≥ 80%) agreed that checklists fit easily into clinic workflow and required ≤ 5 min to complete. Staff (≥ 55%) indicated using checklists with ≥ 75% of their clients. 92% or more reported referring one or more children with potential developmental concerns. According to 80% of staff, parents indicated checklists helped them learn about development and planned to share them with healthcare providers. During the second phase, 18 of 20 staff surveyed indicated the program helped them learn when to refer children and how to support parents, and 19 felt the program promoted healthy development. Focus groups supported survey findings, and all clinics planned to sustain the program. CONCLUSIONS: Initial implementation outcomes supported this approach to developmental monitoring and referral in WIC. The program has potential to help low-income parents identify possible concerns and access support.

Leveraging nonstructural data to predict structures and affinities of protein-ligand complexes.

Over the past five decades, tremendous effort has been devoted to computational methods for predicting properties of ligands-i.e., molecules that bind macromolecular targets. Such methods, which are critical to rational drug design, fall into two categories: physics-based methods, which directly model ligand interactions with the target given the target's three-dimensional (3D) structure, and ligand-based methods, which predict ligand properties given experimental measurements for similar ligands. Here, we present a rigorous statistical framework to combine these two sources of information. We develop a method to predict a ligand's pose-the 3D structure of the ligand bound to its target-that leverages a widely available source of information: a list of other ligands that are known to bind the same target but for which no 3D structure is available. This combination of physics-based and ligand-based modeling improves pose prediction accuracy across all major families of drug targets. Using the same framework, we develop a method for virtual screening of drug candidates, which outperforms standard physics-based and ligand-based virtual screening methods. Our results suggest broad opportunities to improve prediction of various ligand properties by combining diverse sources of information through customized machine-learning approaches.

Binding pathway determines norepinephrine selectivity for the human ß1AR over ß2AR.

Beta adrenergic receptors (ßARs) mediate physiologic responses to the catecholamines epinephrine and norepinephrine released by the sympathetic nervous system. While the hormone epinephrine binds ß1AR and ß2AR with similar affinity, the smaller neurotransmitter norepinephrine is approximately tenfold selective for the ß1AR. To understand the structural basis for this physiologically important selectivity, we solved the crystal structures of the human ß1AR bound to an antagonist carazolol and different agonists including norepinephrine, epinephrine and BI-167107. Structural comparison revealed that the catecholamine-binding pockets are identical between ß1AR and ß2AR, but the extracellular vestibules have different shapes and electrostatic properties. Metadynamics simulations and mutagenesis studies revealed that these differences influence the path norepinephrine takes to the orthosteric pocket and contribute to the different association rates and thus different affinities.

Structure and selectivity engineering of the M1 muscarinic receptor toxin complex.

Muscarinic toxins (MTs) are natural toxins produced by mamba snakes that primarily bind to muscarinic acetylcholine receptors (MAChRs) and modulate their function. Despite their similar primary and tertiary structures, MTs show distinct binding selectivity toward different MAChRs. The molecular details of how MTs distinguish MAChRs are not well understood. Here, we present the crystal structure of M1AChR in complex with MT7, a subtype-selective anti-M1AChR snake venom toxin. The structure reveals the molecular basis of the extreme subtype specificity of MT7 for M1AChR and the mechanism by which it regulates receptor function. Through in vitro engineering of MT7 finger regions that was guided by the structure, we have converted the selectivity from M1AChR toward M2AChR, suggesting that the three-finger fold is a promising scaffold for developing G protein-coupled receptor modulators.

An allosteric modulator binds to a conformational hub in the ß2 adrenergic receptor.

Most drugs acting on G-protein-coupled receptors target the orthosteric binding pocket where the native hormone or neurotransmitter binds. There is much interest in finding allosteric ligands for these targets because they modulate physiologic signaling and promise to be more selective than orthosteric ligands. Here we describe a newly developed allosteric modulator of the ß2-adrenergic receptor (ß2AR), AS408, that binds to the membrane-facing surface of transmembrane segments 3 and 5, as revealed by X-ray crystallography. AS408 disrupts a water-mediated polar network involving E1223.41 and the backbone carbonyls of V2065.45 and S2075.46. The AS408 binding site is adjacent to a previously identified molecular switch for ß2AR activation formed by I3.40, P5.50 and F6.44. The structure reveals how AS408 stabilizes the inactive conformation of this switch, thereby acting as a negative allosteric modulator for agonists and positive allosteric modulator for inverse agonists.

Structure of a D2 dopamine receptor-G-protein complex in a lipid membrane.

The D2 dopamine receptor (DRD2) is a therapeutic target for Parkinson's disease1 and antipsychotic drugs2. DRD2 is activated by the endogenous neurotransmitter dopamine and synthetic agonist drugs such as bromocriptine3, leading to stimulation of Gi and inhibition of adenylyl cyclase. Here we used cryo-electron microscopy to elucidate the structure of an agonist-bound activated DRD2-Gi complex reconstituted into a phospholipid membrane. The extracellular ligand-binding site of DRD2 is remodelled in response to agonist binding, with conformational changes in extracellular loop 2, transmembrane domain 5 (TM5), TM6 and TM7, propagating to opening of the intracellular Gi-binding site. The DRD2-Gi structure represents, to our knowledge, the first experimental model of a G-protein-coupled receptor-G-protein complex embedded in a phospholipid bilayer, which serves as a benchmark to validate the interactions seen in previous detergent-bound structures. The structure also reveals interactions that are unique to the membrane-embedded complex, including helix 8 burial in the inner leaflet, ordered lysine and arginine side chains in the membrane interfacial regions, and lipid anchoring of the G protein in the membrane. Our model of the activated DRD2 will help to inform the design of subtype-selective DRD2 ligands for multiple human central nervous system disorders.

Structure-guided development of selective M3 muscarinic acetylcholine receptor antagonists.

Drugs that treat chronic obstructive pulmonary disease by antagonizing the M3 muscarinic acetylcholine receptor (M3R) have had a significant effect on health, but can suffer from their lack of selectivity against the M2R subtype, which modulates heart rate. Beginning with the crystal structures of M2R and M3R, we exploited a single amino acid difference in their orthosteric binding pockets using molecular docking and structure-based design. The resulting M3R antagonists had up to 100-fold selectivity over M2R in affinity and over 1,000-fold selectivity in vivo. The crystal structure of the M3R-selective antagonist in complex with M3R corresponded closely to the docking-predicted geometry, providing a template for further optimization.

Structure-based discovery of selective positive allosteric modulators of antagonists for the M2 muscarinic acetylcholine receptor.

Subtype-selective antagonists for muscarinic acetylcholine receptors (mAChRs) have long been elusive, owing to the highly conserved orthosteric binding site. However, allosteric sites of these receptors are less conserved, motivating the search for allosteric ligands that modulate agonists or antagonists to confer subtype selectivity. Accordingly, a 4.6 million-molecule library was docked against the structure of the prototypical M2 mAChR, seeking molecules that specifically stabilized antagonist binding. This led us to identify a positive allosteric modulator (PAM) that potentiated the antagonist N-methyl scopolamine (NMS). Structure-based optimization led to compound '628, which enhanced binding of NMS, and the drug scopolamine itself, with a cooperativity factor (α) of 5.5 and a KB of 1.1 µM, while sparing the endogenous agonist acetylcholine. NMR spectral changes determined for methionine residues reflected changes in the allosteric network. Moreover, '628 slowed the dissociation rate of NMS from the M2 mAChR by 50-fold, an effect not observed at the other four mAChR subtypes. The specific PAM effect of '628 on NMS antagonism was conserved in functional assays, including agonist stimulation of [35S]GTPγS binding and ERK 1/2 phosphorylation. Importantly, the selective allostery between '628 and NMS was retained in membranes from adult rat hypothalamus and in neonatal rat cardiomyocytes, supporting the physiological relevance of this PAM/antagonist approach. This study supports the feasibility of discovering PAMs that confer subtype selectivity to antagonists; molecules like '628 can convert an armamentarium of potent but nonselective GPCR antagonist drugs into subtype-selective reagents, thus reducing their off-target effects.

Structure-Based Design and Discovery of New M2 Receptor Agonists.

Muscarinic receptor agonists are characterized by apparently strict restraints on their tertiary or quaternary amine and their distance to an ester or related center. On the basis of the active state crystal structure of the muscarinic M2 receptor in complex with iperoxo, we explored potential agonists that lacked the highly conserved functionalities of previously known ligands. Using structure-guided pharmacophore design followed by docking, we found two agonists (compounds 3 and 17), out of 19 docked and synthesized compounds, that fit the receptor well and were predicted to form a hydrogen-bond conserved among known agonists. Structural optimization led to compound 28, which was 4-fold more potent than its parent 3. Fortified by the discovery of this new scaffold, we sought a broader range of chemotypes by docking 2.2 million fragments, which revealed another three micromolar agonists unrelated either to 28 or known muscarinics. Even pockets as tightly defined and as deeply studied as that of the muscarinic reveal opportunities for the structure-based design and the discovery of new chemotypes.

A randomized controlled trial to evaluate outcomes of a workplace self-management intervention and an intensive monitoring intervention.

The purpose of this study was to determine and compare outcomes of two voluntary workplace health management methods: an adapted worksite self-management (WSM) approach and an intensive health monitoring (IM) approach. Research participants were randomly assigned to either the WSM group or the IM group by a computer-generated list (n = 180; 92 WSM and 88 IM). Participants completed baseline, 3 and 12-month follow-up surveys. Individuals receiving workplace WSM and IM improved in self-efficacy and nearly all health behaviors and health status variables after the intervention, compared to before the intervention. Individuals in the WSM group improved in depression symptoms at 3 and 12 months (P < 0.0001, P < 0.0001), and individuals in the IM group did not improve at either time period (P < 0.1488, P < 0.0521). Participants in the WSM group reported more improvement in physical activity and energy, health interfering less with personal life and daily activities and fewer depression symptoms at follow up, compared to participants in the IM group. This study provided additional support for worksite-based health promotion programs to promote healthy lifestyles and improve health status, and documented effectiveness of both methods, with superior performance and greater scalability for the WSM program.

Racial/Ethnic Differences in the Use of Primary Care Providers and Preventive Health Services at a Midwestern University.

Many universities seek to improve the health and wellbeing of their faculty and staff through employer wellness programs but racial/ethnic disparities in health care use may still persist. The purpose of this research was to identify racial/ethnic disparities in the use of preventive health services at a Midwestern university. A record review was conducted of self-reported health data from University employees, examining the use of primary care and common screening procedures collected in a Personal Health Assessment conducted by the University's wellness program. Results show that there were significant racial/ethnic differences in the use of primary care and participation in screening. Notably, Asian employees in this sample were less likely to have a primary care provider and participate in routine cancer screenings. The observed racial/ethnic differences in screening behavior were mediated by the use of primary care. Together, these data show that despite equal access to care, racial and ethnic disparities in screening persist and that having a primary care provider is an important predictor of screening behavior. Results suggest that health communications designed to increase screening among specific racial/ethnic minority groups should target primary care use.

Act Healthy: promoting health behaviors and self-efficacy in the workplace.

Chronic health conditions and multiple health risk factors afflict Americans and burden employers, but effective, affordable, workplace-based health promotion interventions have not been widely implemented. This is the first study to adapt the empirically validated Chronic Disease Self-Management Program for a general employee population in a workplace setting with an emphasis on disease prevention and health promotion. A quasi-experimental, wellness standard of care comparison, prospective cohort design was used among employee participants at a large University employer. Ninety-one individuals participated in the program. Participants reported significantly increased health behavior frequency and self-efficacy after the intervention, compared with their pre-intervention scores, and improvements were sustained at 3-month follow-up [self-rated abilities for health practices scale (SRA): F = 30.89, P < 0.001; health promoting lifestyle profile-II (HPLP-II): F = 36.30 P < 0.001]. Individuals in the intervention group reported improved self-efficacy and health behaviors compared with the wellness standard of care comparison group at post intervention (SRA: F = 12.45, P < 0.001; HPLP-II: F = 25.28, P < 0.001). Adapting lay-facilitated self-management for the workplace offers promise as a replicable, scalable, affordable model for culture change in organizations.

C7ß-methyl analogues of the orvinols: the discovery of kappa opioid antagonists with nociceptin/orphanin FQ peptide (NOP) receptor partial agonism and low, or zero, efficacy at mu opioid receptors.

Buprenorphine is a successful analgesic and treatment for opioid abuse, with both activities relying on its partial agonist activity at mu opioid receptors. However, there is substantial interest in its activities at the kappa opioid and nociceptin/orphanin FQ peptide receptors. This has led to an interest in developing compounds with a buprenorphine-like pharmacological profile but with lower efficacy at mu opioid receptors. The present article describes aryl ring analogues of buprenorphine in which the standard C20-methyl group has been moved to the C7ß position, resulting in ligands with the desired profile. In particular, moving the methyl group has resulted in far more robust kappa opioid antagonist activity than seen in the standard orvinol series. Of the compounds synthesized, a number, including 15a, have a profile of interest for the development of drug abuse relapse prevention therapies or antidepressants and others (e.g., 8c), as analgesics with a reduced side-effect profile.

Nucleus accumbens shell excitability is decreased by methamphetamine self-administration and increased by 5-HT2C receptor inverse agonism and agonism.

Methamphetamine profoundly increases brain monoamines and is a widely abused psychostimulant. The effects of methamphetamine self-administration on neuron function are not known for the nucleus accumbens, a brain region involved in addictive behaviors, including drug-seeking. One therapeutic target showing preclinical promise at attenuating psychostimulant-seeking is 5-HT2C receptors; however, the effects of 5-HT2C receptor ligands on neuronal physiology are unclear. 5-HT2C receptor agonism decreases psychostimulant-mediated behaviors, and the putative 5-HT2C receptor inverse agonist, SB 206553, attenuates methamphetamine-seeking in rats. To ascertain the effects of methamphetamine, and 5-HT2C receptor inverse agonism and agonism, on neuronal function in the nucleus accumbens, we evaluated methamphetamine, SB 206553, and the 5-HT2C receptor agonist and Ro 60-0175, on neuronal excitability within the accumbens shell subregion using whole-cell current-clamp recordings in forebrain slices ex vivo. We reveal that methamphetamine self-administration decreased generation of evoked action potentials. In contrast, SB 206553 and Ro 60-0175 increased evoked spiking, effects that were prevented by the 5-HT2C receptor antagonist, SB 242084. We also assessed signaling mechanisms engaged by 5-HT2C receptors, and determined that accumbal 5-HT2C receptors stimulated Gq, but not Gi/o. These findings demonstrate that methamphetamine-induced decreases in excitability of neurons within the nucleus accumbens shell were abrogated by both 5-HT2C inverse agonism and agonism, and this effect likely involved activation of Gq-mediated signaling pathways.

Health care transition services for youth with autism spectrum disorders.

OBJECTIVE: Little is known about accessibility to health care transition (HCT) services (HCT) for youth with autism spectrum disorders (ASD). This study examined how often youth with ASD receive HCT services and how access varied by individual, family, and health system characteristics. METHOD: Questionnaires were completed by 101 parents of youth with ASD (ages 12-17 years) enrolled in a national online autism registry. Descriptive statistics and bivariate analysis were used to examine a composite HCT variable and its components. RESULTS: Fewer than 15% of youth received HCT services. Although 41% received at least 1 HCT discussion, only 3% received all 3. One-quarter had a discussion with their health care provider about transitioning to an adult provider, adult health care needs, or insurance retention, and 31% of providers encouraged youth to take on more responsibilities. Most caregivers reported not needing 1 or more of the discussions. RESULTS varied significantly when the sample was divided by age, with older youth more likely to have received transition services than younger adolescents. CONCLUSIONS: These findings indicate a significant disparity in access to HCT services for youth with ASD. Further research is needed to understand this disparity and develop interventions to improve HCT both for youth with ASD and those with other disabling health conditions. Additionally, many caregivers do not recognize the importance of HCT services. Education and training for caregivers, youth, and providers is essential to ensure all parties are working together to address transition issues early and often.

Selectively promiscuous opioid ligands: discovery of high affinity/low efficacy opioid ligands with substantial nociceptin opioid peptide receptor affinity.

Emerging clinical and preclinical evidence suggests that a compound displaying high affinity for µ, κ, and δ opioid (MOP, KOP, and DOP) receptors and antagonist activity at each, coupled with moderate affinity and efficacy at nociceptin opioid peptide (NOP) receptors will have utility as a relapse prevention agent for multiple types of drug abuse. Members of the orvinol family of opioid ligands have the desired affinity profile but have typically displayed substantial efficacy at MOP and or KOP receptors. In this study it is shown that a phenyl ring analogue (1d) of buprenorphine displays the desired profile in vitro with high, nonselective affinity for the MOP, KOP, and DOP receptors coupled with moderate affinity for NOP receptors. In vivo, 1d lacked any opioid agonist activity and was an antagonist of both the MOP receptor agonist morphine and the KOP receptor agonist ethylketocyclazocine, confirming the desired opioid receptor profile in vivo.

Characterization of BU09059: a novel potent selective κ-receptor antagonist.

Kappa-opioid receptor (κ) antagonists are potential therapeutic agents for a range of psychiatric disorders. The feasibility of developing κ-antagonists has been limited by the pharmacodynamic properties of prototypic κ-selective antagonists; that is, they inhibit receptor signaling for weeks after a single administration. To address this issue, novel trans-(3R,4R)-dimethyl-4-(3-hydroxyphenyl) piperidine derivatives, based on JDTic, were designed using soft-drug principles. The aim was to determine if the phenylpiperidine-based series of κ-antagonists was amenable to incorporation of a potentially metabolically labile group, while retaining good affinity and selectivity for the κ-receptor. Opioid receptor binding affinity and selectivity of three novel compounds (BU09057, BU09058, and BU09059) were tested. BU09059, which most closely resembles JDTic, had nanomolar affinity for the κ-receptor, with 15-fold and 616-fold selectivity over µ- and δ-receptors, respectively. In isolated tissues, BU09059 was a potent and selective κ-antagonist (pA2 8.62) compared with BU09057 (pA2 6.87) and BU09058 (pA2 6.76) which were not κ-selective. In vivo, BU09059 (3 and 10 mg/kg) significantly blocked U50,488-induced antinociception and was as potent as, but shorter acting than, the prototypic selective κ-antagonist norBNI. These data show that a new JDTic analogue, BU09059, retains high affinity and selectivity for the κ-receptor and has a shorter duration of κ-antagonist action in vivo.

The relationship between the medical home and unmet needs for children with autism spectrum disorders.

The purpose of this study was to examine the relationship between having access to a medical home and unmet needs for specialty care services for children with autism spectrum disorders (ASD). Parents of children enrolled in a national autism registry were invited to complete an online Access to Care Questionnaire. The resulting sample consisted of 371 parents-child dyads. Bivariate and hierarchical regression analyses were conducted to determine whether having a medical home was associated with the number of unmet needs for specialty care. Less than one in five children with ASD had a medical home (18.9%). Nearly all parents reported that their child had a personal doctor or nurse as well as a usual source of care, but less than one-third received coordinated care (29.9%) and less than one-half received family-centered care (47.1%). Many children had unmet needs (63%), and the highest unmet need was for behavioral therapy. Having a medical home was associated with fewer unmet specialty care needs, even after demographic, child and family characteristics were taken into account. Children with ASD who have a medical home are more likely to have adequate access to needed services. Unfortunately, relatively few children have a medical home that includes family-centered and coordinated care. Enhancements in the delivery of primary care for children with ASD may make a real difference in access to needed specialty care services, potentially improving child and family outcomes.