Rat Hepatitis E Virus Isolates Cluster among Urban Norway Rats (Rattus norvegicus) across a Roadway.

Hepatitis E virus (HEV) is a globally distributed pathogen that causes acute hepatitis in people. Recent human cases of HEV arising after contact with urban rats (Rattus spp.) have raised concerns regarding whether rats may be a source of HEV infection.

Assessing avian influenza surveillance intensity in wild birds using a One Health lens.

Wildlife disease surveillance, particularly for pathogens with zoonotic potential such as Highly Pathogenic Avian Influenza Virus (HPAIV), is critical to facilitate situational awareness, inform risk, and guide communication and response efforts within a One Health framework. This study evaluates the intensity of avian influenza virus (AIV) surveillance in Ontario's wild bird population following the 2021 H5N1 incursion into Canada. Analyzing 2562 samples collected between November 1, 2021, and October 31, 2022, in Ontario, Canada, we identify spatial variations in surveillance intensity relative to human population density, poultry facility density, and wild mallard abundance.

Potent activity of polymyxin B is associated with long-lived super-stoichiometric accumulation mediated by weak-affinity binding to lipid A.

Polymyxins are gram-negative antibiotics that target lipid A, the conserved membrane anchor of lipopolysaccharide in the outer membrane. Despite their clinical importance, the molecular mechanisms underpinning polymyxin activity remain unresolved. Here, we use surface plasmon resonance to kinetically interrogate interactions between polymyxins and lipid A and derive a phenomenological model.

Engineered Cytochrome P450-Catalyzed Oxidative Biaryl Coupling Reaction Provides a Scalable Entry into Arylomycin Antibiotics.

We report herein the first example of a cytochrome P450-catalyzed oxidative carbon-carbon coupling process for a scalable entry into arylomycin antibiotic cores. Starting from wild-type hydroxylating cytochrome P450 enzymes and engineered , a combination of enzyme engineering, random mutagenesis, and optimization of reaction conditions generated a P450 variant that affords the desired arylomycin core in 84% assay yield. Furthermore, this process was demonstrated as a viable route for the production of the arylomycin antibiotic core on the gram scale.

Challenges in the structure determination of a dimeric impurity found during development of GDC-0326.

While developing a synthetic route for GDC-0326, a PI3Kα selective inhibitor, a side product was identified which was adversely impacting process chemistry development. To aid in optimization of a viable synthetic pathway for the drug, it was decided to characterize this impurity. Initial efforts using typical high-resolution mass spectrometry data coupled with NMR analysis were unable to unambiguously identify the structure.

Evaluating the utility of pest control sourced rats for zoonotic pathogen surveillance.

Norway rats (Rattus norvegicus) inhabit cities worldwide and live in close association with humans. Studies of urban rat zoonoses often rely on live-trapping, with fewer studies using rats sourced through lethal pest control interventions. Our objectives were to evaluate the utility of rats collected by pest control professionals for zoonotic pathogen surveillance and determine whether we could detect Leptospira interrogans and Streptobacillus moniliformis in pest control sourced rats.

Incorporating NOE-Derived Distances in Conformer Generation of Cyclic Peptides with Distance Geometry.

Nuclear magnetic resonance (NMR) data from NOESY (nuclear Overhauser enhancement spectroscopy) and ROESY (rotating frame Overhauser enhancement spectroscopy) experiments can easily be combined with distance geometry (DG) based conformer generators by modifying the molecular distance bounds matrix. In this work, we extend the modern DG based conformer generator ETKDG, which has been shown to reproduce experimental crystal structures from small molecules to large macrocycles well, to include NOE-derived interproton distances. In noeETKDG, the experimentally derived interproton distances are incorporated into the distance bounds matrix as loose upper (or lower) bounds to generate large conformer sets.

Stereocontrolled Synthesis of Arylomycin-Based Gram-Negative Antibiotic GDC-5338.

We report herein an efficient, stereocontrolled, and chromatography-free synthesis of the novel broad spectrum antibiotic . The route features the construction of a functionalized tripeptide backbone, a high-yielding macrocyclization via a Pd-catalyzed Suzuki-Miyaura reaction, and the late-stage elaboration of key amide bonds with minimal stereochemical erosion. Through extensive reaction development and analytical understanding, these key advancements allowed the preparation of in 17 steps, 15% overall yield, >99 A % HPLC, and >99:1 dr.

Identification of an acetonitrile addition impurity formed during peptide disulfide bond reduction using dithiothreitol and Tris(2-carboxyethyl)phosphine.

Identification and localization of modifications in peptides containing multiple disulfide bonds is challenging due to inefficient fragmentation in mass spectrometry (MS) analysis. In cases where MS fragmentation techniques such as electron capture dissociation (ECD), electron transfer dissociation (ETD), and ultraviolet photodissociation (UVPD) fail to achieve efficient fragmentation, off-line disulfide bond reduction techniques are typically employed prior to MS analysis. Some commonly used reducing agents include dithiothreitol (DTT) and tris(2-carboxyethyl)phosphine (TCEP).

Synthesis of Selective Estrogen Receptor Degrader GDC-0810 via Stereocontrolled Assembly of a Tetrasubstituted All-Carbon Olefin.

We report an efficient synthesis of GDC-0810 on the basis of a sequence involving a highly stereoselective lithium tert-butoxide-mediated enolization-tosylation (≥95:5 E: Z) and a Pd-catalyzed Suzuki-Miyaura cross-coupling as key steps. Global deprotection, pyrrolidine salt formation, and final active pharmaceutical ingredient (API) form control/isolation produced GDC-0810 free acid in a 40% overall yield with >99.0% purity as ascertained by HPLC analysis.

Characterizing the in vitro species differences in N-glucuronidation of a potent pan-PIM inhibitor GNE-924 containing a 3,5-substituted 6-azaindazole.

1. Glucuronidation of amines has been shown to exhibit large species differences, where the activity is typically more pronounced in human than in many preclinical species such as rat, mouse, dog and monkey. The purpose of this work was to characterize the in vitro glucuronidation of GNE-924, a potent pan-PIM inhibitor, to form M1 using liver microsomes (LM) and intestinal microsomes (IM).

Elucidating the Mechanisms of Formation for Two Unusual Cytochrome P450-Mediated Fused Ring Metabolites of GDC-0623, a MAPK/ERK Kinase Inhibitor.

Two isomeric metabolites of GDC-0623 [5-((2-fluoro-4-iodophenyl)amino)-N-(2-hydroxyethoxy)imidazo[1,5-a]pyridine-6-carboxamide], a mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) kinase inhibitor, were identified in radiolabeled mass balance studies in rats and dogs (approximately 5% in excreta) and were also observed in human circulation (nonradiolabeled). Mass spectrometric data indicated that both metabolites had formed a new ring structure fused to the imidazopyridine core. Given their unusual structures, we conducted experiments to elucidate their chemical structures and understand the mechanisms for their formation.

The Use of TOC Reconciliation as a Means of Establishing the Degree to Which Chromatographic Screening of Plastic Material Extracts for Organic Extractables Is Complete.

Unlabelled: Extracts of plastic packaging, manufacturing, and delivery systems (or their materials of construction) are analyzed by chromatographic methods to establish the system's extractables profile. The testing strategy consists of multiple orthogonal chromatographic methods, for example, gas and liquid chromatography with multiple detection strategies. Although this orthogonal testing strategy is comprehensive, it is not necessarily complete and members of the extractables profile can elude detection and/or accurate identification/quantification.

A proteomic survey of nonribosomal peptide and polyketide biosynthesis in actinobacteria.

Actinobacteria such as streptomycetes are renowned for their ability to produce bioactive natural products including nonribosomal peptides (NRPs) and polyketides (PKs). The advent of genome sequencing has revealed an even larger genetic repertoire for secondary metabolism with most of the small molecule products of these gene clusters still unknown. Here, we employed a "protein-first" method called PrISM (Proteomic Investigation of Secondary Metabolism) to screen 26 unsequenced actinomycetes using mass spectrometry-based proteomics for the targeted detection of expressed nonribosomal peptide synthetases or polyketide synthases.

Proteomics-based discovery of koranimine, a cyclic imine natural product.

Nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) are large enzymes responsible for the biosynthesis of medically and ecologically important secondary metabolites. In a previous report, we described a proteomics approach to screen for expressed NRPSs or PKSs from bacteria with or without sequenced genomes. Here we used this proteome mining approach to discover a novel natural product arising from rare adenylation (A) and reductase (Red) domains in its biosynthetic machinery.

Biostructural features of additional jasplakinolide (jaspamide) analogues.

The cyclodepsipeptide jasplakinolide (1) (aka jaspamide), isolated previously from the marine sponge Jaspis splendens, is a unique cytotoxin and molecular probe that operates through stabilization of filamentous actin (F-actin). We have recently disclosed that two analogues of 1, jasplakinolides B (3) and E, were referred to the National Cancer Institute's (NCI) Biological Evaluation Committee, and the objective of this study was to reinvestigate a Fijian collection of J. splendens in an effort to find jasplakinolide congeners with similar biological properties.

Surveys of non-ribosomal peptide and polyketide assembly lines in fungi and prospects for their analysis in vitro and in vivo.

With many bioactive non-ribosomal peptides and polyketides produced in fungi, studies of their biosyntheses are an active area of research. Practical limitations of working with mega-dalton synthetases including cell lysis and protein extraction to recombinant gene and pathway expression has slowed understanding of many secondary metabolic processes relative to bacterial counterparts. Recent advances in accessing fungal biosynthetic machinery are beginning to change this.

New structures and bioactivity properties of jasplakinolide (jaspamide) analogues from marine sponges.

The goal of this study was to isolate and study additional jasplakinolide analogues from two taxonomically distinct marine sponges including two Auletta spp. and one Jaspis splendens. This led to the isolation of jasplakinolide (1) and eleven jasplakinolide analogues (3-13) including seven new analogues (6-10, 12, and 13).

Using enzyme assays to evaluate the structure and bioactivity of sponge-derived meroterpenes.

Enzyme screening of crude sponge extracts prioritized a 2005 Papua New Guinea collection of Hyrtios sp. for further study. The MeOH extract contained puupehenone and four puupehenone analogues (1, 2, 3, 5, and 7) along with a new diastereomer, 20-epi-hydroxyhaterumadienone (4), and a new analogue, 15-oxo-puupehenoic acid (6).

Building research capacity for evidence-informed tobacco control in Canada: a case description.

Tobacco use remains the leading cause of death and disability in Canada. Insufficient research capacity can inhibit evidence-informed decision making for tobacco control. This paper outlines a Canadian project to build research capacity, defined as a community's ability to produce research that adequately informs practice, policy, and future research in a timely, practical manner.

Polyketide assembly lines of uncultivated sponge symbionts from structure-based gene targeting.

There is increasing evidence that uncultivated bacterial symbionts are the true producers of numerous bioactive compounds isolated from marine sponges. The localization and heterologous expression of biosynthetic genes could clarify this issue and provide sustainable supplies for a wide range of pharmaceuticals. However, identification of genes in the usually highly complex symbiont communities remains a challenging task.

Revisiting the sponge sources, stereostructure, and biological activity of cyclocinamide a.

The dramatic biogeographical variations in the secondary metabolites from Psammocinia aff. bulbosa have complicated our efforts to reisolate the two most cytotoxic of its metabolites, (+)-psymberin and (+)-cyclocinamide A. Reported now are the results of a new study that demonstrates our ability to repeatedly isolate these two compounds through targeted collection efforts.