Early Colonoscopy in Hospitalized Patients With Acute Lower Gastrointestinal Bleeding: A Nationwide Analysis.

Background: Performing colonoscopy within 24 h of presentation to the hospital is the accepted standard of care for patients with an acute lower gastrointestinal bleed (LGIB). Previous studies have failed to demonstrate the benefit of early colonoscopy (EC) on mortality. In this study, we wanted to see if there was a change in inpatient deaths (primary outcome), length of stay (LOS), and hospitalization charges (TOTCHG) (secondary outcomes) with EC compared to previous studies. Methods: Adults diagnosed with LGIB were identified using the International Classification of Disease 10th Revision codes from the National Inpatient Sample database for 2016 to 2019. EC was defined as the procedure performed within 24 h of hospitalization. Delayed colonoscopy (DC) was defined as a procedure performed after 24 h of presentation. The patient population was divided into EC and DC groups, and the effects of several covariates on outcomes were measured using binary logistic and multivariate regression analysis. Inverse probability treatment weighting (IPTW) was performed to adjust for confounding covariates. Results: There were 1,549,065 cases diagnosed with LGIB, of which 285,165 cases (18.4%) received a colonoscopy. A total of 107,045 (6.9%) patients received early colonoscopies. EC was associated with decreased inpatient deaths (0.9% in EC, and 1.4% in DC, P < 0.001). However, upon IPTW, this difference was not present. EC was associated with a decreased LOS (median 3 days vs. 5 days, P < 0.001) and TOTCHG (median $32,037 vs. $44,092, P < 0.001). Weekend admissions (WA) were associated with fewer EC (31.6% in WA, and 39.5% in non-WA, P < 0.001). WA did not affect inpatient deaths. Conclusions: EC was not associated with decreased inpatient deaths. There was no difference in endoscopic interventions in both EC and DC groups. The difference in inpatient deaths observed between the two groups was not evident upon adjusting the results for confounders. EC was associated with a decreased LOS, and TOTCHG in patients with LGIB.

Investigation of orexin-2 selective receptor antagonists: Structural modifications resulting in dual orexin receptor antagonists.

In an ongoing effort to explore the use of orexin receptor antagonists for the treatment of insomnia, dual orexin receptor antagonists (DORAs) were structurally modified, resulting in compounds selective for the OX2R subtype and culminating in the discovery of 23, a highly potent, OX2R-selective molecule that exhibited a promising in vivo profile. Further structural modification led to an unexpected restoration of OX1R antagonism. Herein, these changes are discussed and a rationale for selectivity based on computational modeling is proposed.

Discovery of highly potent and selective orexin 1 receptor antagonists (1-SORAs) suitable for in vivo interrogation of orexin 1 receptor pharmacology.

While a correlation between blockade of the orexin 2 receptor (OX2R) with either a dual orexin receptor antagonist (DORA) or a selective orexin 2 receptor antagonist (2-SORA) and a decrease of wakefulness is well established, less is known about selective blockade of the orexin 1 receptor (OX1R). Therefore, a highly selective orexin 1 antagonist (1-SORA) with suitable properties to allow in vivo interrogation of OX1R specific pharmacology in preclinical species remains an attractive target. Herein, we describe the discovery of an optimized 1-SORA series in the piperidine ether class. Notably, a 4,4-difluoropiperidine core coupled with a 2-quinoline ether linkage provides OX1R selective compounds. The combination with an azabenzimidazole or imidazopyridine amide substituent leads to analogs 47 and 51 with >625-fold functional selectivity for OX1R over OX2R in rat. Compounds 47 and 51 possess clean off-target profiles and the required pharmacokinetic and physical properties to be useful as 1-SORA tool compounds.

Novel oxazolidinone calcitonin gene-related peptide (CGRP) receptor antagonists for the acute treatment of migraine.

In our efforts to develop CGRP receptor antagonists as backups to MK-3207, 2, we employed a scaffold hopping approach to identify a series of novel oxazolidinone-based compounds. The development of a structurally diverse, potent (20, cAMP+HS IC50=0.67 nM), and selective compound (hERG IC50=19 µM) with favorable rodent pharmacokinetics (F=100%, t1/2=7h) is described. Key to this development was identification of a 3-substituted spirotetrahydropyran ring that afforded a substantial gain in potency (10 to 35-fold).

Identification of MK-8133: An orexin-2 selective receptor antagonist with favorable development properties.

Antagonism of orexin receptors has shown clinical efficacy as a novel paradigm for the treatment of insomnia and related disorders. Herein, molecules related to the dual orexin receptor antagonist filorexant were transformed into compounds that were selective for the OX2R subtype. Judicious selection of the substituents on the pyridine ring and benzamide groups led to 6b; which was highly potent, OX2R selective, and exhibited excellent development properties.

Discovery of piperidine ethers as selective orexin receptor antagonists (SORAs) inspired by filorexant.

Highly selective orexin receptor antagonists (SORAs) of the orexin 2 receptor (OX2R) have become attractive targets both as potential therapeutics for insomnia as well as biological tools to help further elucidate the underlying pharmacology of the orexin signaling pathway. Herein, we describe the discovery of a novel piperidine ether 2-SORA class identified by systematic lead optimization beginning with filorexant, a dual orexin receptor antagonist (DORA) that recently completed Phase 2 clinical trials. Changes to the ether linkage and pendant heterocycle of filorexant were found to impart significant selectivity for OX2R, culminating in lead compound PE-6. PE-6 displays sub-nanomolar binding affinity and functional potency on OX2R while maintaining >1600-fold binding selectivity and >200-fold functional selectivity versus the orexin 1 receptor (OX1R). PE-6 bears a clean off-target profile, a good overall preclinical pharmacokinetic (PK) profile, and reduces wakefulness with increased NREM and REM sleep when evaluated in vivo in a rat sleep study. Importantly, subtle structural changes to the piperidine ether class impart dramatic changes in receptor selectivity. To this end, our laboratories have identified multiple piperidine ether 2-SORAs, 1-SORAs, and DORAs, providing access to a number of important biological tool compounds from a single structural class.

Discovery of MK-3697: a selective orexin 2 receptor antagonist (2-SORA) for the treatment of insomnia.

Orexin receptor antagonists have demonstrated clinical utility for the treatment of insomnia. The majority of clinical efforts to date have focused on the development of dual orexin receptor antagonists (DORAs), small molecules that antagonize both the orexin 1 and orexin 2 receptors. Our group has recently disclosed medicinal chemistry efforts to identify highly potent, orally bioavailable selective orexin 2 receptor antagonists (2-SORAs) that possess acceptable profiles for clinical development. Herein we report additional SAR studies within the 'triaryl' amide 2-SORA series focused on improvements in compound stability in acidic media and time-dependent inhibition of CYP3A4. These studies resulted in the discovery of 2,5-disubstituted isonicotinamide 2-SORAs such as compound 24 that demonstrated improved stability and TDI profiles as well as excellent sleep efficacy across species.

Synthesis and evaluation of carbon-linked analogs of dual orexin receptor antagonist filorexant.

Analogs of the dual orexin receptor antagonist filorexant were prepared. Replacement of the ether linkage proved highly sensitive toward modification with an acetylene linkage providing compounds with the best in vitro and in vivo potency profiles.

Discovery of 5''-chloro-N-[(5,6-dimethoxypyridin-2-yl)methyl]-2,2':5',3''-terpyridine-3'-carboxamide (MK-1064): a selective orexin 2 receptor antagonist (2-SORA) for the treatment of insomnia.

The field of small-molecule orexin antagonist research has evolved rapidly in the last 15 years from the discovery of the orexin peptides to clinical proof-of-concept for the treatment of insomnia. Clinical programs have focused on the development of antagonists that reversibly block the action of endogenous peptides at both the orexin 1 and orexin 2 receptors (OX1 R and OX2 R), termed dual orexin receptor antagonists (DORAs), affording late-stage development candidates including Merck's suvorexant (new drug application filed 2012). Full characterization of the pharmacology associated with antagonism of either OX1 R or OX2 R alone has been hampered by the dearth of suitable subtype-selective, orally bioavailable ligands. Herein, we report the development of a selective orexin 2 antagonist (2-SORA) series to afford a potent, orally bioavailable 2-SORA ligand. Several challenging medicinal chemistry issues were identified and overcome during the development of these 2,5-disubstituted nicotinamides, including reversible CYP inhibition, physiochemical properties, P-glycoprotein efflux and bioactivation. This article highlights structural modifications the team utilized to drive compound design, as well as in vivo characterization of our 2-SORA clinical candidate, 5''-chloro-N-[(5,6-dimethoxypyridin-2-yl)methyl]-2,2':5',3''-terpyridine-3'-carboxamide (MK-1064), in mouse, rat, dog, and rhesus sleep models.

Discovery of 2,5-diarylnicotinamides as selective orexin-2 receptor antagonists (2-SORAs).

The orexin (or hypocretin) system has been identified as a novel target for the treatment of insomnia due to the wealth of biological and genetic data discovered over the past decade. Recently, clinical proof-of-concept was achieved for the treatment of primary insomnia using dual (OX1R/OX2R) orexin receptor antagonists. However, elucidation of the pharmacology associated with selective orexin-2 receptor antagonists (2-SORAs) has been hampered by the lack of orally bioavailable, highly selective small molecule probes. Herein, the discovery and optimization of a novel series of 2,5-diarylnicotinamides as potent and orally bioavailable orexin-2 receptor selective antagonists is described. A compound from this series demonstrated potent sleep promotion when dosed orally to EEG telemetrized rats.

OX40L/Jagged1 cosignaling by GM-CSF-induced bone marrow-derived dendritic cells is required for the expansion of functional regulatory T cells.

Earlier, we had demonstrated that treatment with low dose of GM-CSF can prevent the development of experimental autoimmune thyroiditis (EAT), experimental autoimmune myasthenia gravis, and type 1 diabetes, and could also reverse ongoing EAT and experimental autoimmune myasthenia gravis. The protective effect was mediated through the induction of tolerogenic CD11C(+)CD8α(-) dendritic cells (DCs) and consequent expansion of Foxp3(+) regulatory T cells (Tregs). Subsequently, we showed that GM-CSF acted specifically on bone marrow precursors and facilitated their differentiation into tolerogenic dendritic cells (DCs; GM-CSF-induced bone marrow-derived DCs [GM-BMDCs]), which directed Treg expansion in a contact-dependent manner. This novel mechanism of Treg expansion was independent of TCR-mediated signaling but required exogenous IL-2 and cosignaling from DC-bound OX40L. In this study, we observed that OX40L-mediated signaling by GM-BMDCs, although necessary, was not sufficient for Treg expansion and required signaling by Jagged1. Concurrent signaling induced by OX40L and Jagged1 via OX40 and Notch3 receptors expressed on Tregs was essential for the Treg expansion with sustained FoxP3 expression. Adoptive transfer of only OX40L(+)Jagged1(+) BMDCs led to Treg expansion, increased production of IL-4 and IL-10, and suppression of EAT in the recipient mice. These results showed a critical role for OX40L- and Jagged1-induced cosignaling in GM-BMDC-induced Treg expansion.

[(11)C]MK-4232: The First Positron Emission Tomography Tracer for the Calcitonin Gene-Related Peptide Receptor.

Rational modification of the potent calcitonin gene-related peptide (CGRP) receptor antagonist MK-3207 led to a series of analogues with enhanced CNS penetrance and a convenient chemical handle for introduction of a radiolabel. A number of (11)C-tracers were synthesized and evaluated in vivo, leading to the identification of [(11)C]8 ([(11)C]MK-4232), the first positron emission tomography tracer for the CGRP receptor.

MK-8825: a potent and selective CGRP receptor antagonist with good oral activity in rats.

Rational modification of the clinically tested CGRP receptor antagonist MK-3207 (3) afforded an analogue with increased unbound fraction in rat plasma and enhanced aqueous solubility, 2-[(8R)-8-(3,5-difluorophenyl)-8-methyl-10-oxo-6,9-diazaspiro[4.5]dec-9-yl]-N-[(6S)-2'-oxo-1',2',5,7-tetrahydrospiro[cyclopenta[b]pyridine-6,3'-pyrrolo[2,3-b]pyridin]-3-yl]acetamide (MK-8825) (6). Compound 6 maintained similar affinity to 3 at the human and rat CGRP receptors but possessed significantly improved in vivo potency in a rat pharmacodynamic model. The overall profile of 6 indicates it should find utility as a rat tool to investigate effects of CGRP receptor blockade in vivo.

Listeria monocytogenes adapts to long-term stationary phase survival without compromising bacterial virulence.

Bacteria withstand starvation during long-term stationary phase through the acquisition of mutations that increase bacterial fitness. The evolution of the growth advantage in stationary phase (GASP) phenotype results in the ability of bacteria from an aged culture to outcompete bacteria from a younger culture when the two are mixed together. The GASP phenotype was first described for Escherichia coli, but has not been examined for an environmental bacterial pathogen, which must balance long-term survival strategies that promote fitness in the outside environment with those that promote fitness within the host. Listeria monocytogenes is an environmental bacterium that lives as a saprophyte in soil, but is capable of replicating within the cytosol of mammalian cells. Herein, we demonstrate the ability of L. monocytogenes to express GASP via the acquisition of mutations during long-term stationary growth. Listeria monocytogenes GASP occurred through mechanisms that were both dependent and independent of the stress-responsive alternative sigma factor SigB. Constitutive activation of the central virulence transcriptional regulator PrfA interfered with the development of GASP; however, L. monocytogenes GASP cultures retained full virulence in mice. These results indicate that L. monocytogenes can accrue mutations that optimize fitness during long-term stationary growth without negatively impacting virulence.

Discordant lymphoma consisting of splenic mantle cell lymphoma and marginal zone lymphoma involving the bone marrow and peripheral blood: a case report.

INTRODUCTION: Discordant lymphomas are rare entities characterized by the simultaneous presence of two distinct types of lymphomas in different anatomic sites. We describe a very rare case of simultaneous occurrence of splenic mantle cell lymphoma and marginal zone lymphoma involving the bone marrow and peripheral blood. CASE PRESENTATION: We report the case of a 60-year-old asymptomatic Caucasian woman in whom discordant lymphomas were discovered when a slight lymphocytosis and a conspicuous splenomegaly were observed. The different morphological, immunophenotypical and immunohistochemical features found in the different pathologic samples obtained from peripheral blood, bone marrow and spleen sections made it possible to differentiate two types of non-Hodgkin B-cell lymphomas: a mantle cell lymphoma infiltrating the spleen and a marginal zone lymphoma involving both the bone marrow and peripheral blood. Since a similar IgH gene rearrangement was found both in the bone marrow and in the spleen, the hypothesis of a common origin, followed by a different clonal selection of the neoplastic lymphocytes may be taken into consideration. CONCLUSION: Our case emphasizes the usefulness of investigating simultaneous specimens from different anatomic sites from the same patient and the relevant diagnostic role of splenectomy.

Structure-based design and synthesis of 1,3-oxazinan-2-one inhibitors of 11ß-hydroxysteroid dehydrogenase type 1.

Structure based design led directly to 1,3-oxazinan-2-one 9a with an IC(50) of 42 nM against 11ß-HSD1 in vitro. Optimization of 9a for improved in vitro enzymatic and cellular potency afforded 25f with IC(50) values of 0.8 nM for the enzyme and 2.5 nM in adipocytes. In addition, 25f has 94% oral bioavailability in rat and >1000× selectivity over 11ß-HSD2. In mice, 25f was distributed to the target tissues, liver, and adipose, and in cynomolgus monkeys a 10 mg/kg oral dose reduced cortisol production by 85% following a cortisone challenge.

Constitutive activation of PrfA tilts the balance of Listeria monocytogenes fitness towards life within the host versus environmental survival.

PrfA is a key regulator of Listeria monocytogenes pathogenesis and induces the expression of multiple virulence factors within the infected host. PrfA is post-translationally regulated such that the protein becomes activated upon bacterial entry into the cell cytosol. The signal that triggers PrfA activation remains unknown, however mutations have been identified (prfA* mutations) that lock the protein into a high activity state. In this report we examine the consequences of constitutive PrfA activation on L. monocytogenes fitness both in vitro and in vivo. Whereas prfA* mutants were hyper-virulent during animal infection, the mutants were compromised for fitness in broth culture and under conditions of stress. Broth culture prfA*-associated fitness defects were alleviated when glycerol was provided as the principal carbon source; under these conditions prfA* mutants exhibited a competitive advantage over wild type strains. Glycerol and other three carbon sugars have been reported to serve as primary carbon sources for L. monocytogenes during cytosolic growth, thus prfA* mutants are metabolically-primed for replication within eukaryotic cells. These results indicate the critical need for environment-appropriate regulation of PrfA activity to enable L. monocytogenes to optimize bacterial fitness inside and outside of host cells.

Contribution of chitinases to Listeria monocytogenes pathogenesis.

Listeria monocytogenes secretes two chitinases and one chitin binding protein. Mutants lacking chiA, chiB, or lmo2467 exhibited normal growth in cultured cells but were defective for growth in the livers and spleens of mice. Mammals lack chitin; thus, L. monocytogenes may have adapted chitinases to recognize alternative substrates to enhance pathogenesis.

Novel CGRP receptor antagonists from central amide replacements causing a reversal of preferred chirality.

A previously utilized quinoline-for-N-phenylamide replacement strategy was employed against a central amide in a novel class of CGRP receptor antagonists. A unique and unexpected substitution pattern was ultimately required to maintain reasonable affinity for the CGRP receptor, while at the same time predicting acceptable heterocycle positioning for related analogs. Subsequently, specific quinoline and naphthyridine compounds were prepared which supported these structural predictions by displaying CGRP binding affinities in the 0.037-0.15 nM range.

Discovery and optimization of adamantyl carbamate inhibitors of 11ß-HSD1.

Synthesis of 2-adamantyl carbamate derivatives of piperidines and pyrrolidines led to the discovery of 9a with an IC(50) of 15.2 nM against human 11ß-HSD1 in adipocytes. Optimization for increased adipocyte potency, metabolic stability and selectivity afforded 11k and 11l, both of which were >25% orally bioavailable in rat.