Bedside Magnetocardiography with a Scalar Sensor Array.

Decades of research have shown that magnetocardiography (MCG) has the potential to improve cardiac care decisions. However, sensor and system limitations have prevented its widespread adoption in clinical practice. We report an MCG system built around an array of scalar, optically pumped magnetometers (OPMs) that effectively rejects ambient magnetic interference without magnetic shielding. We successfully used this system, in conjunction with custom hardware and noise rejection algorithms, to record magneto-cardiograms and functional magnetic field maps from 30 volunteers in a regular downtown office environment. This demonstrates the technical feasibility of deploying our device architecture at the point-of-care, a key step in making MCG usable in real-world settings.

Primary caregiver education level and sleep problems in children with autism spectrum disorder.

In children with autism spectrum disorder, there have been equivocal results regarding primary caregiver education level and its influence on sleep. Thus, we assessed if lower primary caregiver education level is associated with more sleep problems. We evaluated 4,636 children with autism spectrum disorder in the Autism Speaks Autism Treatment Network's United States and Canadian registry, whose caregivers completed the Children's Sleep Habits Questionnaire. Using regression analysis, there was an association between lower primary caregiver education level and more sleep problems. Secondary analyses demonstrated that younger age, Hispanic ethnicity, higher IQ, autism diagnosis and lower adaptive function were also associated with more sleep problems. The finding that lower primary caregiver education level was associated with increased sleep problems in a large sample of children with autism spectrum disorder highlights the importance of screening for risk factors affecting sleep to help moderate sleep problems.

Child Behavior Problems and Parenting Stress in Underserved Families of Children with ASD: Investigation of Family Resources and Parenting Self-efficacy.

Behavior problems in children with autism spectrum disorder (ASD) may exacerbate parenting stress. Parenting self-efficacy and family resources may influence this association. We examined cross-sectional statistical mediation effects of parenting self-efficacy on the relationship between child behavior problems and parenting stress and hypothesized that family-level resources moderated this indirect effect. Participants included 132 underserved (Medicaid-eligible) children with ASD (ages 3-13) with racial/ethnic diversity; many (63%) had intellectual disability. Greater externalizing problems were linked with lower parenting self-efficacy, which in turn was associated with increased parenting stress. A larger mediation effect was observed for families with fewer resources. A plausible alternative model (parenting stress mediating parenting self-efficacy) exhibited poorer fit. Implications for family supports and benefits of longitudinal follow-up are discussed.

Quantitative proteomic analysis of human substantia nigra in Alzheimer's disease, Huntington's disease and Multiple sclerosis.

The substantia nigra plays important roles in the brain function and is critical in the development of many diseases, particularly Parkinson's disease. Pathological changes of the substantia nigra have also been reported in other neurodegenerative diseases. Using a quantitative proteomic approach, we investigated protein expressions in the substantia nigra of Alzheimer's disease, Huntington's disease, and Multiple sclerosis. The expression level of one hundred and four proteins that were identified in at least three samples of each group were compared with the control group, with nineteen, twenty-two and thirteen proteins differentially expressed in Alzheimer's diseases, Huntington's disease and Multiple sclerosis respectively. The result indicates that the substantia nigra also undergoes functional adaption or damage in these diseases.

Parent Training for Dental Care in Underserved Children With Autism: A Randomized Controlled Trial.

OBJECTIVE: Children with autism spectrum disorder (ASD) have difficulty participating in dental care and experience significant unmet dental needs. We examined the efficacy of parent training (PT) for improving oral hygiene and oral health in underserved children with ASD. METHOD: Families of Medicaid-eligible children with ASD (ages 3-13 years, 85% boys, 62% with intellectual disability) reporting difficulty with dental care participated in a 6-month randomized controlled trial comparing PT (n = 60) with a psychoeducational dental toolkit (n = 59). Primary outcomes were parent-reported frequency of twice-daily toothbrushing and dentist-rated visible plaque. Secondary outcomes included parent-reported child behavior problems during home oral hygiene and dentist-rated caries. Dentists were blind to intervention assignment. Analyses were intention to treat. RESULTS: Retention was high at posttreatment (3 months, 93%) and 6-month follow-up (90%). Compared with the toolkit intervention, PT was associated with increased twice-daily toothbrushing at 3 (78% vs 55%, respectively; P < .001) and 6 (78% vs 62%; P = .002) months and a reduction in plaque at 3 months (intervention effect, -0.19; 95% confidence interval [CI], -0.36 to -0.02; P = .03) and child problem behaviors at 3 (-0.90; 95% CI, -1.52 to -0.28; P = .005) and 6 (-0.77; 95% CI, -1.39 to -0.14; P = .02) months. Comparatively fewer caries developed in children receiving the PT intervention over 3 months (ratio of rate ratios, 0.73; 95% CI, 0.54 to 0.99; P = .04). CONCLUSIONS: PT represents a promising approach for improving oral hygiene and oral health in underserved children with ASD at risk for dental problems.

Understanding the Link Between Obesity and Severe COVID-19 Outcomes: Causal Mediation by Systemic Inflammatory Response.

BACKGROUND: Obesity is an established risk factor for severe COVID-19 outcomes. The mechanistic underpinnings of this association are not well-understood. OBJECTIVE: To evaluate the mediating role of systemic inflammation in obesity-associated COVID-19 outcomes. METHODS: This hospital-based, observational study included 3828 SARS-CoV-2-infected patients who were hospitalized February to May 2020 at Massachusetts General Hospital (MGH) or Columbia University Irving Medical Center/New York Presbyterian Hospital (CUIMC/NYP). We use mediation analysis to evaluate whether peak inflammatory biomarkers (C-reactive protein [CRP], erythrocyte sedimentation rate [ESR], D-dimer, ferritin, white blood cell count and interleukin-6) are in the causal pathway between obesity (BMI ≥ 30) and mechanical ventilation or death within 28 days of presentation to care. RESULTS: In the MGH cohort (n = 1202), obesity was associated with greater likelihood of ventilation or death (OR = 1.73; 95% CI = [1.25, 2.41]; P = 0.001) and higher peak CRP (P < 0.001) compared with nonobese patients. The estimated proportion of the association between obesity and ventilation or death mediated by CRP was 0.49 (P < 0.001). Evidence of mediation was more pronounced in patients < 65 years (proportion mediated = 0.52 [P < 0.001] vs 0.44 [P = 0.180]). Findings were more moderate but consistent for peak ESR. Mediation by other inflammatory markers was not supported. Results were replicated in CUIMC/NYP cohort (n = 2626). CONCLUSION: Findings support systemic inflammatory pathways in obesity-associated severe COVID-19 disease, particularly in patients < 65 years, captured by CRP and ESR. Contextualized in clinical trial findings, these results reveal therapeutic opportunity to target systemic inflammatory pathways and monitor interventions in high-risk subgroups and particularly obese patients.

A REDCap-based model for online interventional research: Parent sleep education in autism.

INTRODUCTION: The use of online platforms for pediatric healthcare research is timely, given the current pandemic. These platforms facilitate trial efficiency integration including electronic consent, randomization, collection of patient/family survey data, delivery of an intervention, and basic data analysis. METHODS: We created an online digital platform for a multicenter study that delivered an intervention for sleep disorders to parents of children with autism spectrum disorder (ASD). An advisory parent group provided input. Participants were randomized to receive either a sleep education pamphlet only or the sleep education pamphlet plus three quick-tips sheets and two videos that reinforced the material in the pamphlet (multimedia materials). Three measures - Family Inventory of Sleep Habits (FISH), Children's Sleep Habits Questionnaire modified for ASD (CSHQ-ASD), and Parenting Sense of Competence (PSOC) - were completed before and after 12 weeks of sleep education. RESULTS: Enrollment exceeded recruitment goals. Trial efficiency was improved, especially in data entry and automatic notification of participants related to survey completion. Most families commented favorably on the study. While study measures did not improve with treatment in either group (pamphlet or multimedia materials), parents reporting an improvement of ≥3 points in the FISH score showed a significantly improved change in the total CSHQ (P = 0.038). CONCLUSION: Our study demonstrates the feasibility of using online research delivery platforms to support studies in ASD, and more broadly, pediatric clinical and translational research. Online platforms may increase participant inclusion in enrollment and increase convenience and safety for participants and study personnel.

Factors Associated With Seizure Onset in Children With Autism Spectrum Disorder.

BACKGROUND AND OBJECTIVES: Children with autism spectrum disorder (ASD) have a higher prevalence of epilepsy compared with general populations. In this pilot study, we prospectively identified baseline risk factors for the development of seizures in individuals with ASD and also identified characteristics sensitive to seizure onset up to 6 years after enrollment in the Autism Speaks Autism Treatment Network. METHODS: Children with ASD and no history of seizures at baseline who either experienced onset of seizures after enrollment in the Autism Treatment Network or remained seizure free were included in the analysis. RESULTS: Among 472 qualifying children, 22 (4.7%) experienced onset of seizures after enrollment. Individuals who developed seizures after enrollment exhibited lower scores at baseline on all domains of the Vineland Adaptive Behavior Scales, greater hyperactivity on the Aberrant Behavior Checklist (25.4 ± 11.8 vs 19.2 ± 11.1; P = .018), and lower physical quality of life scores on the Pediatric Quality of Life Inventory (60.1 ± 24.2 vs 76.0 ± 18.2; P < .001). Comparing change in scores from entry to call-back, adjusting for age, sex, length of follow-up, and baseline Vineland II composite score, individuals who developed seizures experienced declines in daily living skills (-8.38; 95% confidence interval -14.50 to -2.50; P = .005). Adjusting for baseline age, sex, and length of follow-up, baseline Vineland II composite score was predictive of seizure development (risk ratio = 0.95 per unit Vineland II composite score, 95% confidence interval 0.92 to 0.99; P = .007). CONCLUSIONS: Individuals with ASD at risk for seizures exhibited changes in adaptive functioning and behavior.

Racial and Ethnic Differences in Behavioral Problems and Medication Use Among Children With Autism Spectrum Disorders.

We examined racial and ethnic differences in the prevalence of behavioral problems measured by the Child Behavioral Checklist (CBCL), sleep disturbances measured by the Child Sleep Habits Questionnaire (CSHQ), and medication use among children with Autism Spectrum Disorders (ASD). We analyzed data from the Autism Treatment Network (ATN) dataset for 2,576 children ages 6 to 18 years of age diagnosed with ASD. Multivariable logistic regression accounting for age, gender, Diagnostic and Statistical Manual of Mental Disorders (4th Edition - Text Revision), diagnosis (Autistic Disorder, PDD-NOS, Asperger's Disorder), and parents' education did not show any racial or ethnic differences in behavioral challenges, conduct problems, or sleep disturbances for any of the groups, but Black children had lower odds of Total Problem Behaviors and Asian children had lower odds of Hyperactivity compared to White children. As a group, children from racial and ethnic minorities had lower odds of Total Problem Behaviors and Conduct Problems compared to White children. Hispanic children had lower odds of medication use for Behavioral Challenges, Total Problem Behaviors, Hyperactivity, and Conduct Problems. Asian children had lower odds of medication use for Behavioral Challenges, Total Problem Behaviors, and Hyperactivity; and had close to lower odds in medication use for Conduct Problems. Black children had lower odds for medication use for Total Problem Behaviors only. As a group, children from racial and ethnic minorities had lower odds for medication use for Behavioral Challenges, Total Problem Behaviors, Hyperactivity, and Conduct problems, but not for Sleep Disturbances. While these results are consistent with previous studies showing that White children are significantly more likely to receive psychotropic medication compared to children from racial and ethnic minority groups, we found no such differences for sleep challenges, suggesting that they are more consistently identified and equitably treated than other behavioral problems associated with ASD. We draw upon Andersen's (1995) Behavioral Model of Healthcare Use to suggest predisposing, enabling, and needs factors that may contribute to this pattern of racial and ethnic differences in the use of medications among children ASD.

Higher Acuity Resource Utilization With Older Age and Poorer HIV Control in Adolescents and Young Adults in the HIV Research Network.

BACKGROUND: Adolescents and young adults (AYA) with HIV experience poorer health outcomes compared with adults. To improve care for AYA with HIV, information about patterns of costly health care resource utilization is needed. METHODS: Among 13-30 year olds in the US HIV Research Network, we stratified outpatient visits, emergency department (ED) visits, and inpatient days/person-year (PY) by HIV acquisition model [perinatal (PHIVY) and nonperinatal (NPHIVY)], age (13-17, 18-23, and 24-30 years), CD4 strata (<200, 200-499, and ≥500 cells/µL), and viral load (VL) suppression (<, ≥400 copies/mL [c/mL]) combined with antiretroviral (ARV) use. RESULTS: Among 4540 AYA (PHIVY: 15%; NPHIVY: 85%), mean follow-up was 2.8 years. Among PHIVY, most person-time (PT) was spent between ages 13 and 23 years (13-17 years: 43%; 18-23 years: 45%), CD4 ≥500/µL (61%), and VL <400 c/mL (69%). Among NPHIVY, most PT was spent between ages 24 and 30 years (56%), with CD4 ≥500/µL (54%), and with VL <400 c/mL (67%). PT spent while prescribed ARVs and with VL ≥400 c/mL was 29% (PHIVY) and 24% (NPHIVY). For PHIVY and NPHIVY, outpatient visit rates were higher at younger ages (13-17 years and 18-23 years), lower CD4 (<200 and 200-499/µL), and among those prescribed ARVs. Rates of ED visits and inpatient days were higher during PT spent at older ages (18-23 years and 24-30 years), lower CD4 (<200 and 200-499/µL), and VL ≥400 c/mL. Utilization was higher among PHIVY than NPHIVY (outpatient: 12.1 vs. 6.0/PY; ED: 0.4 vs. 0.3/PY; inpatient: 1.5 vs. 0.8/PY). CONCLUSIONS: More ED visits and inpatient days were observed during time spent at older ages, lower CD4 count, and VL ≥400 c/mL. Interventions to improve virologic suppression and immune response may improve outcomes, and thus decrease costly resource utilization, for AYA with HIV.

Massachusetts general hospital Covid-19 registry reveals two distinct populations of hospitalized patients by race and ethnicity.

OBJECTIVE: To evaluate differences by race/ethnicity in clinical characteristics and outcomes among hospitalized patients with Covid-19 at Massachusetts General Hospital (MGH). METHODS: The MGH Covid-19 Registry includes confirmed SARS-CoV-2-infected patients hospitalized at MGH and is based on manual chart reviews and data extraction from electronic health records (EHRs). We evaluated differences between White/Non-Hispanic and Hispanic patients in demographics, complications and 14-day outcomes among the N = 866 patients hospitalized with Covid-19 from March 11, 2020-May 4, 2020. RESULTS: Overall, 43% of patients hospitalized with Covid-19 were women, median age was 60.4 [IQR = (48.2, 75)], 11.3% were Black/non-Hispanic and 35.2% were Hispanic. Hispanic patients, representing 35.2% of patients, were younger than White/non-Hispanic patients [median age 51y; IQR = (40.6, 61.6) versus 72y; (58.0, 81.7) (p<0.001)]. Hispanic patients were symptomatic longer before presenting to care (median 5 vs 3d, p = 0.039) but were more likely to be sent home with self-quarantine than be admitted to hospital (29% vs 16%, p<0.001). Hispanic patients had fewer comorbidities yet comparable rates of ICU or death (34% vs 36%). Nonetheless, a greater proportion of Hispanic patients recovered by 14 days after presentation (62% vs 45%, p<0.001; OR = 1.99, p = 0.011 in multivariable adjusted model) and fewer died (2% versus 18%, p<0.001). CONCLUSIONS: Hospitalized Hispanic patients were younger and had fewer comorbidities compared to White/non-Hispanic patients; despite comparable rates of ICU care or death, a greater proportion recovered. These results have implications for public health policy and the design and conduct of clinical trials.

Factors associated with DSM-5 severity level ratings for autism spectrum disorder.

The newest edition of the Diagnostic and Statistical Manual of Mental Disorders (5th ed., DSM-5) introduced substantial changes to the diagnostic criteria for autism spectrum disorder, including new severity level ratings for social communication and restricted and repetitive behavior domains. The purpose of this study was to evaluate the use of these new severity ratings and to examine their relation to other measures of severity and clinical features. Participants included 248 children with autism spectrum disorder who received diagnostic evaluations at one of six Autism Treatment Network sites. Higher severity ratings in both domains were associated with younger age, lower intelligence quotient, and greater Autism Diagnostic Observation Schedule-Second Edition domain-specific symptom severity. Greater restricted and repetitive behavior severity was associated with higher parent-reported stereotyped behaviors. Severity ratings were not associated with emotional or behavioral problems. The new DSM-5 severity ratings in both domains were significantly associated with behavioral observations of autism severity but not with measures of other behavioral or emotional symptoms. However, the strong associations between intelligence quotient and DSM-5 severity ratings in both domains suggest that clinicians may be including cognitive functioning in their overall determination of severity. Further research is needed to examine clinician decision-making and interpretation of these specifiers.

Probiotics for Gastrointestinal Symptoms and Quality of Life in Autism: A Placebo-Controlled Pilot Trial.

Objective: A randomized pilot trial of gastrointestinal (GI) symptoms targeting probiotic for quality of life in autism spectrum disorder (ASD). Methods: Thirteen children, 3-12 years of age with ASD, anxiety, and GI symptoms, were randomized into a probiotic crossover trial of 8 weeks each on VISBIOME and placebo separated by a 3-week washout. VISBIOME contains eight probiotic species, mostly Lactobacillus and Bifidobacterium. Primary outcome was the Pediatric Quality of Life Inventory (PedsQL) GI module. Secondary outcomes included gut microbiota analysis, the Parent-Rated Anxiety Scale for ASD (PRAS-ASD), and parent-selected target symptoms. A mixed analysis model was applied. Results: Thirteen children were randomized, with 10 completing the study (77% retention): 6 in probiotic/placebo sequence, 4 in placebo/probiotic sequence. Adherence to study treatment was 96%. There were no serious adverse events (AEs), and more nonserious AEs occurred with placebo than with probiotic, including those attributable to treatment. Only 6 of the 10 guessed the correct treatment at the end of week 8. Over the 19-week trial, each outcome improved from baseline and PedsQL correlated significantly with abundance of Lactobacillus without discernable changes to microbiota composition/diversity. Although probiotic showed more improvement than placebo, PedsQL and PRAS-ASD were not statistically significant, as expected at this sample size. PedsQL effect size was d = 0.49 by the general model and d = 0.79 by simple comparison of week 8 changes. A parent-selected target symptom showed significant improvement in GI complaints on probiotic compared with placebo (p = 0.02, d = 0.79). Probiotic effects carried over through the 3-week washout. Conclusion: The VISBIOME formulation was safe and suggested a health benefit in children with ASD and GI symptoms who retained Lactobacillus. The moderate effect size compared with placebo warrants a larger trial using a parallel-group design.

Structural basis for GPR40 allosteric agonism and incretin stimulation.

Activation of free fatty acid receptor 1 (GPR40) by synthetic partial and full agonists occur via distinct allosteric sites. A crystal structure of GPR40-TAK-875 complex revealed the allosteric site for the partial agonist. Here we report the 2.76-Å crystal structure of human GPR40 in complex with a synthetic full agonist, compound 1, bound to the second allosteric site. Unlike TAK-875, which acts as a Gαq-coupled partial agonist, compound 1 is a dual Gαq and Gαs-coupled full agonist. compound 1 binds in the lipid-rich region of the receptor near intracellular loop 2 (ICL2), in which the stabilization of ICL2 by the ligand is likely the primary mechanism for the enhanced G protein activities. The endogenous free fatty acid (FFA), γ-linolenic acid, can be computationally modeled in this site. Both γ-linolenic acid and compound 1 exhibit positive cooperativity with TAK-875, suggesting that this site could also serve as a FFA binding site.

Synthesis and Pharmacological Characterization of C4ß-Amide-Substituted 2-Aminobicyclo[3.1.0]hexane-2,6-dicarboxylates. Identification of (1 S,2 S,4 S,5 R,6 S)-2-Amino-4-[(3-methoxybenzoyl)amino]bicyclo[3.1.0]hexane-2,6-dicarboxylic Acid (LY2794193), a Highly Potent and Selective mGlu3 Receptor Agonist.

Multiple therapeutic opportunities have been suggested for compounds capable of selective activation of metabotropic glutamate 3 (mGlu3) receptors, but small molecule tools are lacking. As part of our ongoing efforts to identify potent, selective, and systemically bioavailable agonists for mGlu2 and mGlu3 receptor subtypes, a series of C4ß-N-linked variants of (1 S,2 S,5 R,6 S)-2-amino-bicyclo[3.1.0]hexane-2,6-dicarboxylic acid 1 (LY354740) were prepared and evaluated for both mGlu2 and mGlu3 receptor binding affinity and functional cellular responses. From this investigation we identified (1 S,2 S,4 S,5 R,6 S)-2-amino-4-[(3-methoxybenzoyl)amino]bicyclo[3.1.0]hexane-2,6-dicarboxylic acid 8p (LY2794193), a molecule that demonstrates remarkable mGlu3 receptor selectivity. Crystallization of 8p with the amino terminal domain of hmGlu3 revealed critical binding interactions for this ligand with residues adjacent to the glutamate binding site, while pharmacokinetic assessment of 8p combined with its effect in an mGlu2 receptor-dependent behavioral model provides estimates for doses of this compound that would be expected to selectively engage and activate central mGlu3 receptors in vivo.

A Prospective Study of the Concordance of DSM-IV and DSM-5 Diagnostic Criteria for Autism Spectrum Disorder.

The transition from DSM-IV to DSM-5 criteria for autism spectrum disorder (ASD) sparked considerable concern about the potential implications of these changes. This study was designed to address limitations of prior studies by prospectively examining the concordance of DSM-IV and final DSM-5 criteria on a consecutive sample of 439 children referred for autism diagnostic evaluations. Concordance and discordance were assessed using a consistent diagnostic battery. DSM-5 criteria demonstrated excellent overall specificity and good sensitivity relative to DSM-IV criteria. Sensitivity and specificity were strongest for children meeting DSM-IV criteria for autistic disorder, but poor for those meeting criteria for Asperger's disorder and pervasive developmental disorder. Higher IQ, older age, female sex, and less pronounced ASD symptoms were associated with greater discordance.

Computationally Designed Bispecific Antibodies using Negative State Repertoires.

A challenge in the structure-based design of specificity is modeling the negative states, i.e., the complexes that you do not want to form. This is a difficult problem because mutations predicted to destabilize the negative state might be accommodated by small conformational rearrangements. To overcome this challenge, we employ an iterative strategy that cycles between sequence design and protein docking in order to build up an ensemble of alternative negative state conformations for use in specificity prediction. We have applied our technique to the design of heterodimeric CH3 interfaces in the Fc region of antibodies. Combining computationally and rationally designed mutations produced unique designs with heterodimer purities greater than 90%. Asymmetric Fc crystallization was able to resolve the interface mutations; the heterodimer structures confirmed that the interfaces formed as designed. With these CH3 mutations, and those made at the heavy-/light-chain interface, we demonstrate one-step synthesis of four fully IgG-bispecific antibodies.

Synthesis and pharmacological characterization of C4-disubstituted analogs of 1S,2S,5R,6S-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate: identification of a potent, selective metabotropic glutamate receptor agonist and determination of agonist-bound human mGlu2 and mGlu3 amino terminal domain structures.

As part of our ongoing research to identify novel agents acting at metabotropic glutamate 2 (mGlu2) and 3 (mGlu3) receptors, we have previously reported the identification of the C4α-methyl analog of mGlu2/3 receptor agonist 1 (LY354740). This molecule, 1S,2S,4R,5R,6S-2-amino-4-methylbicyclo[3.1.0]hexane-2,6-dicarboxylate 2 (LY541850), exhibited an unexpected mGlu2 agonist/mGlu3 antagonist pharmacological profile, whereas the C4ß-methyl diastereomer (3) possessed dual mGlu2/3 receptor agonist activity. We have now further explored this structure-activity relationship through the preparation of cyclic and acyclic C4-disubstituted analogs of 1, leading to the identification of C4-spirocyclopropane 5 (LY2934747), a novel, potent, and systemically bioavailable mGlu2/3 receptor agonist which exhibits both antipsychotic and analgesic properties in vivo. In addition, through the combined use of protein-ligand X-ray crystallography employing recombinant human mGlu2/3 receptor amino terminal domains, molecular modeling, and site-directed mutagenesis, a molecular basis for the observed pharmacological profile of compound 2 is proposed.

Synthesis and Pharmacological Characterization of C4-(Thiotriazolyl)-substituted-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylates. Identification of (1R,2S,4R,5R,6R)-2-Amino-4-(1H-1,2,4-triazol-3-ylsulfanyl)bicyclo[3.1.0]hexane-2,6-dicarboxylic Acid (LY2812223), a Highly Potent, Functionally Selective mGlu2 Receptor Agonist.

Identification of orthosteric mGlu(2/3) receptor agonists capable of discriminating between individual mGlu2 and mGlu3 subtypes has been highly challenging owing to the glutamate-site sequence homology between these proteins. Herein we detail the preparation and characterization of a series of molecules related to (1S,2S,5R,6S)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate 1 (LY354740) bearing C4-thiotriazole substituents. On the basis of second messenger responses in cells expressing other recombinant human mGlu2/3 subtypes, a number of high potency and efficacy mGlu2 receptor agonists exhibiting low potency mGlu3 partial agonist/antagonist activity were identified. From this, (1R,2S,4R,5R,6R)-2-amino-4-(1H-1,2,4-triazol-3-ylsulfanyl)bicyclo[3.1.0]hexane-2,6-dicarboxylic acid 14a (LY2812223) was further characterized. Cocrystallization of 14a with the amino terminal domains of hmGlu2 and hmGlu3 combined with site-directed mutation studies has clarified the underlying molecular basis of this unique pharmacology. Evaluation of 14a in a rat model responsive to mGlu2 receptor activation coupled with a measure of central drug disposition provides evidence that this molecule engages and activates central mGlu2 receptors in vivo.