Antagonism of Propofol Anesthesia by Alkyl-fluorobenzene Derivatives.

Despite their frequent use across many clinical settings, general anesthetics are medications with lethal side effects and no reversal agents. A fluorinated analogue of propofol has previously been shown to antagonize propofol anesthesia in tadpoles and zebrafish, but little further investigation of this class of molecules as anesthetic antagonists has been conducted. A 13-member library of alkyl-fluorobenzene derivatives was tested in an established behavioral model of anesthesia in zebrafish at 5 days post fertilization. These compounds were examined for their ability to antagonize propofol and two volatile anesthetics, as well as their binding to the anesthetic-binding model protein apoferritin. The two compounds demonstrating highest antagonistic potency were found to bind apoferritin in a manner similar to propofol. Selected compounds did not show antagonism of volatile anesthetics, indicating some selectivity of this antagonism. Similarities in structure and binding to apoferritin as well as a Schild analysis are suggestive of competitive antagonism, but like the anesthetics, the potential mechanism(s) of these antagonists will require further mechanistic investigation.

Subclinical to catastrophic: a range of outcomes in cerebral air embolism.

Cerebral air embolism (CAE) is a rare, yet potentially devastating condition characterized by entrance of air into cerebral vasculature, that is nearly always iatrogenic. While many findings of CAE are subclinical and incidental at computed tomography (CT), there remain cases of catastrophic and fatal embolisms. Increasing physician awareness of prevention, presentation, and treatment for CAE is crucial for reducing morbidity and mortality. In this case series, we highlight this preventable entity by comparing three cases of CAE that showcase a diverse array of presentations, radiologic findings, and clinical outcomes. We will also explore predisposing factors, prognostic predictors, diagnostic considerations, and available treatments.

The conserved crown bridge loop at the catalytic centre of enzymes of the haloacid dehalogenase superfamily.

The crown bridge loop is hexapeptide motif in which the backbone carbonyl group at position 1 is hydrogen bonded to the backbone imino groups of positions 4 and 6. Residues at positions 1 and 4-6 are held in a tight substructure, but different orientations of the plane of the peptide bond between positions 2 and 3 result in two conformers: the 2,3-αRαR crown bridge loop - found in approximately 7% of proteins - and the 2,3-ßRαL crown bridge loop, found in approximately 1-2% of proteins. We constructed a relational database in which we identified 60 instances of the 2,3-ßRαL conformer, and find that about half occur in enzymes of the haloacid dehalogenase (HAD) superfamily, where they are located next to the catalytic aspartate residue. Analysis of additional enzymes of the HAD superfamily in the extensive SCOPe dataset showed this crown bridge loop to be a conserved feature. Examination of available structures showed that the 2,3-ßRαL conformation - but not the 2,3-αRαR conformation - allows the backbone carbonyl group at position 2 to interact with the essential Mg2+ ion. The possibility of interconversion between the 2,3-ßRαL and 2,3-αRαR conformations during catalysis is discussed.

Comparative evaluation of Luminex based assays for detection of SARS-CoV-2 antibodies in a transplantation laboratory.

BACKGROUND: Detection of SARS-CoV-2 antibodies is essential in establishing the parameters of an individual's immune response to COVID-19, from both natural infection and vaccination. Despite this, there is currently limited clinical guidance or recommendations for serological methods for their measurement. Here, we evaluate and compare four Luminex-based assays for the multiplex detection of IgG SARS-CoV-2 antibodies. METHODS: The four assays tested were Magnetic Luminex Assay, MULTICOV-AB Assay, Luminex xMAP SARS-CoV-2 Multi-Antigen IgG Assay and LABScreen COVID Plus Assay. Each assay's ability to detect antibodies to SARS-CoV-2 Spike (S), Nucleocapsid (N) and Spike-Receptor Binding Domain (RBD) was evaluated using 50 test samples (25 positive, 25 negative), previously tested by a widely used ELISA technique. RESULTS: The MULTICOV-AB Assay had the highest clinical performance detecting antibodies to S trimer and RBD in 100% (n = 25) of known positive samples. Both the Magnetic Luminex Assay and LABScreen COVID Plus Assay showed significant diagnostic accuracy with sensitivities of 90% and 88% respectively. The Luminex xMAP SARS-CoV-2 Multi-Antigen IgG Assay demonstrated limited detection of antibodies to the S antigen resulting in a sensitivity of 68%. CONCLUSION: Luminex-based assays provide a suitable serological method for multiplex detection of SARS-CoV-2 specific antibodies, with each assay able to detect antibodies to a minimum of 3 different SARS-CoV-2 antigens. Assay comparison identified there is moderate performance variability between manufacturers and further inter-assay variation of antibodies detected to different SARS-CoV-2 antigens.

Public health response to outbreaks of highly pathogenic avian influenza (H5N1) among poultry in Northeast of Ireland, November 2021 to January 2022.

OBJECTIVES: Human infections from highly pathogenic avian influenza (HPAI) H5N1 are associated with significant morbidity and mortality internationally. This study aimed to use routinely available data to examine key strategies to prevent H5N1 transmission to humans during outbreaks in poultry in residents in Cavan, Louth, Meath and Monaghan. STUDY DESIGN: This was a cross-sectional based study. METHODS: Data were obtained from Health Protection Team in the Department of Public Health, HSE North East and Department of Agriculture, Food, and the Marine (DAFM). Data entry and analyses were conducted using Microsoft Excel 2016. RESULTS: The public health response focussed on contact tracing, monitoring and follow-up for household, farm workers and DAFM staff exposed on the affected farms. A total of 157 contact episodes were identified. Contacts received advice about active monitoring from their last exposure. A total of 111 (80%) were recommended chemoprophylaxis for exposure to HPAI H5N1. During the active monitoring period, two contacts developed acute respiratory symptoms, and parainfluenza 3 and rhino/enterovirus were identified in these individuals, respectively. CONCLUSIONS: The findings of this study, using routinely gathered data, highlighted that collaboration between public health and DAFM at regional and national levels was key to rapid response to these outbreaks of HPAI in domesticated poultry. In addition, the public health response appears to have been successful in preventing H5N1 transmission from domesticated birds to humans.

A critical evaluation of the EU-virtual consultation platform (CPMS) within the European Reference Network on Rare Endocrine Conditions.

In 2017, the European Commission installed 24 European Reference Networks (ERNs) for different categories of rare and complex conditions to facilitate cross-border health care via virtual case consultations in a secure Clinical Patient Management System (CPMS). The ERN for rare endocrine conditions (Endo-ERN) previously reviewed the CPMS, in which they detailed the difficulties physicians encountered with the system and proposed solutions to these that should enable the system to be used to a greater extent. This paper will further the endeavor of the first by performing a critical evaluation of the CPMS, assessing how these suggested improvements have been implemented, and if these have affected the usage of the system. The evaluation involves an assessment of CPMS usage statistics since its conception that takes into consideration the technical updates and the external factors that may have affected these, including data from a review survey following a training workshop for our new healthcare providers (HCPs) added in January 2022. It appears that the improvements made to the system since the first review, in particular the implementation of the Operational Helpdesk, have had a positive effect in increasing CPMS membership; however, the regular usage of the system continues to fluctuate. Several suggestions are made on how to further facilitate the use of CPMS by our members both individually and network-wide, by integrating CPMS activities with other network initiatives and further integrating these into national health care systems as well as looking for ways to measure patient satisfaction from the CPMS discussions outcomes.

A framework for mapping and monitoring human-ocean interactions in near real-time during COVID-19 and beyond.

The human response to the COVID-19 pandemic set in motion an unprecedented shift in human activity with unknown long-term effects. The impacts in marine systems are expected to be highly dynamic at local and global scales. However, in comparison to terrestrial ecosystems, we are not well-prepared to document these changes in marine and coastal environments. The problems are two-fold: 1) manual and siloed data collection and processing, and 2) reliance on marine professionals for observation and analysis. These problems are relevant beyond the pandemic and are a barrier to understanding rapidly evolving blue economies, the impacts of climate change, and the many other changes our modern-day oceans are undergoing. The "Our Ocean in COVID-19″ project, which aims to track human-ocean interactions throughout the pandemic, uses the new eOceans platform (eOceans.app) to overcome these barriers. Working at local scales, a global network of ocean scientists and citizen scientists are collaborating to monitor the ocean in near real-time. The purpose of this paper is to bring this project to the attention of the marine conservation community, researchers, and the public wanting to track changes in their area. As our team continues to grow, this project will provide important baselines and temporal patterns for ocean conservation, policy, and innovation as society transitions towards a new normal. It may also provide a proof-of-concept for real-time, collaborative ocean monitoring that breaks down silos between academia, government, and at-sea stakeholders to create a stronger and more democratic blue economy with communities more resilient to ocean and global change.

Electronic search programs are effective in identifying patients with minimal trauma fractures.

We assessed two electronic search tools that screen medical records for documented fractures. Both programs reliably identified patients with any fracture but missed individuals with minimal trauma fracture to different degrees. A hybrid tool combining the methodology of both tools is likely to improve the identification of those with osteoporosis. PURPOSE: Most patients who suffer a minimal trauma fracture remain undiagnosed, placing them at high risk of refracture. Case finding can be improved by electronic search tools that screen medical records for documented fractures. Here, we assessed the efficacy of two new programs, AES and XRAIT, in identifying patients with minimal trauma fracture. METHODS: Each tool was applied to search the electronic medical record and/or radiology reports at two tertiary hospitals in Sydney, Australia, from 1 July to 31 December 2018. Samples of the extracted reports were then manually reviewed to determine the sensitivity of each program in detecting minimal trauma fractures. RESULTS: At the two centers, AES detected 872 and 1364 cases, whereas XRAIT identified 1414 and 2180 patients with fractures, respectively. The true positive rate for "any fracture" was similar for both instruments (77-88%). However, the ability to detect "minimal trauma fractures" differed between programs and centers (53-75% accuracy), with each tool identifying separate subsets of patients. Concordance between both tools was less than half of the combined total number of minimal trauma fractures (43-45%). Considering the total number of minimal trauma fractures detected by both tools combined, AES correctly identified 52-55% of cases while XRAIT identified 88-93% of cases. CONCLUSION: Both programs reliably identified patients with any fracture but missed individuals with minimal trauma fracture to different degrees. Hybrid tools combining the methodology of XRAIT and AES are likely to improve the identification of patients who require investigation and treatment for osteoporosis.

The ß-link motif in protein architecture.

The ß-link is a composite protein motif consisting of a G1ß ß-bulge and a type II ß-turn, and is generally found at the end of two adjacent strands of antiparallel ß-sheet. The 1,2-positions of the ß-bulge are also the 3,4-positions of the ß-turn, with the result that the N-terminal portion of the polypeptide chain is orientated at right angles to the ß-sheet. Here, it is reported that the ß-link is frequently found in certain protein folds of the SCOPe structural classification at specific locations where it connects a ß-sheet to another area of a protein. It is found at locations where it connects one ß-sheet to another in the ß-sandwich and related structures, and in small (four-, five- or six-stranded) ß-barrels, where it connects two ß-strands through the polypeptide chain that crosses an open end of the barrel. It is not found in larger (eight-stranded or more) ß-barrels that are straightforward ß-meanders. In some cases it initiates a connection between a single ß-sheet and an α-helix. The ß-link also provides a framework for catalysis in serine proteases, where the catalytic serine is part of a conserved ß-link, and in cysteine proteases, including Mpro of human SARS-CoV-2, in which two residues of the active site are located in a conserved ß-link.

Determination of amino acids that favour the αL region using Ramachandran propensity plots. Implications for α-sheet as the possible amyloid intermediate.

In amyloid diseases an insoluble amyloid fibril forms via a soluble oligomeric intermediate. It is this intermediate that mediates toxicity and it has been suggested, somewhat controversially, that it has the α-sheet structure. Nests and α-strands are similar peptide motifs in that alternate residues lie in the αR and γL regions of the Ramachandran plot for nests, or αR and αL regions for α-strands. In nests a concavity is formed by the main chain NH atoms whereas in α-strands the main chain is almost straight. Using "Ramachandran propensity plots" to focus on the αL/γL region, it is shown that glycine favours γL (82% of amino acids are glycine), but disfavours αL (3% are glycine). Most charged and polar amino acids favour αL with asparagine having by far the highest propensity. Thus, glycine favours nests but, contrary to common expectation, should not favour α-sheet. By contrast most charged or polar amino acids should favour α-sheet by their propensity for the αL conformation, which is more discriminating amongst amino acids than the αR conformation. Thus, these results suggest the composition of sequences that favour α-sheet formation and point towards effective prediction of α-sheet from sequence.

Frequency, breed predisposition and demographic risk factors for overweight status in dogs in the UK.

OBJECTIVES: To evaluate the prevalence and risk factors for overweight status in dogs under primary veterinary care in the UK. MATERIALS AND METHODS: A retrospective study design was used to estimate the 1-year (2016) period prevalence of overweight status. The clinical records were randomly ordered and manually validated for dogs with overweight status during 2016. Univariable and multivariable logistic regression modelling were used to evaluate associations between risk factors (breed, brachycephalic status, adult bodyweight, bodyweight relative to breed-sex mean, age, sex-neuter and insurance) and overweight status. RESULTS: There were 1580 of 22,333 dogs identified as overweight during 2016. The estimated 1-year period prevalence for overweight status recorded in dogs under veterinary care was 7.1% (95% confidence interval 6.7-7.4). After accounting for confounding factors, eight breeds showed increased odds of overweight status compared with crossbred dogs. The breeds with the highest odds included the Pug (OR 3.12, 95% confidence interval 2.31 to 4.20), Beagle (OR 2.67, 1.75 to 4.08), Golden Retriever (OR 2.58, 1.79 to 3.74) and English Springer Spaniel (OR 1.98, 1.31 to 2.98). Being neutered, middle-aged and insured were additionally associated with overweight status. CLINICAL SIGNIFICANCE: Targeted overweight prevention strategies should be prioritised for predisposed breeds, such as Pugs and Beagles. The findings additionally raise questions about further preventative efforts following neutering. The prevalence estimate suggests veterinary professionals are underreporting overweight status and therefore could be missing key welfare opportunities.

The Pharyngolaryngeal Venous Plexus: A Potential Pitfall in Surveillance Imaging of the Neck.

BACKGROUND AND PURPOSE: Among patients undergoing serial neck CTs, we have observed variability in the appearance of the pharyngolaryngeal venous plexus, which comprises the postcricoid and posterior pharyngeal venous plexuses. We hypothesize changes in plexus appearance from therapeutic neck irradiation. The purposes of this study are to describe the CT appearance of the pharyngolaryngeal venous plexus among 2 groups undergoing serial neck CTs-patients with radiation therapy-treated laryngeal cancer and patients with medically treated lymphoma-and to assess for changes in plexus appearance attributable to radiation therapy. MATERIALS AND METHODS: For this retrospective study of 98 patients (49 in each group), 448 contrast-enhanced neck CTs (222 laryngeal cancer; 226 lymphoma) were assessed. When visible, the plexus anteroposterior diameter was measured, and morphology was categorized. RESULTS: At least 1 plexus component was identified in 36/49 patients with laryngeal cancer and 37/49 patients with lymphoma. There were no statistically significant differences in plexus visibility between the 2 groups. Median anteroposterior diameter was 2.1 mm for the postcricoid venous plexus and 1.6 mm for the posterior pharyngeal venous plexus. The most common morphology was "bilobed" for the postcricoid venous plexus and "linear" for the posterior pharyngeal venous plexus. The pharyngolaryngeal venous plexus and its components were commonly identifiable only on follow-up imaging. CONCLUSIONS: Head and neck radiologists should be familiar with the typical location and variable appearance of the pharyngolaryngeal plexus components so as not to mistake them for neoplasm. Observed variability in plexus appearance is not attributable to radiation therapy.

Identification and characterization of two classes of G1 ß-bulge.

In standard ß-bulges, a residue in one strand of a ß-sheet forms hydrogen bonds to two successive residues (`1' and `2') of a second strand. Two categories, `classic' and `G1' ß-bulges, are distinguished by their dihedral angles: 1,2-αRßR (classic) or 1,2-αLßR (G1). It had previously been observed that G1 ß-bulges are most often found as components of two quite distinct composite structures, suggesting that a basis for further differentiation might exist. Here, it is shown that two subtypes of G1 ß-bulges, G1α and G1ß, may be distinguished by their conformation (αR or ßR) at residue `0' of the second strand. ß-Bulges that are constituents of the composite structure named the ß-bulge loop are of the G1α type, whereas those that are constituents of the composite structure named ß-link here are of the G1ß type. A small proportion of G1ß ß-bulges, but not G1α ß-bulges, occur in other contexts. There are distinctive differences in amino-acid composition and sequence pattern between these two types of G1 ß-bulge which may have practical application in protein design.

Synthesis and Characterization of a Diazirine-Based Photolabel of the Nonanesthetic Fropofol.

The mechanisms of general anesthetics have been debated in the literature for many years and continue to be of great interest. As anesthetic molecules are notoriously difficult to study due to their low binding affinities and multitude of binding partners, it is advantageous to have additional tools to study these interactions. Fropofol is a hydroxyl to fluorine-substituted propofol analogue that is able to antagonize the actions of propofol. Understanding fropofol's ability to antagonize propofol would facilitate further characterization of the binding interactions of propofol that may contribute to its anesthetic actions. However, the study of fropofol's molecular interactions has many of the same difficulties as its parent compound. Here, we present the synthesis and characterization of ortho-azi-fropofol (AziFo) as a suitable photoaffinity label (PAL) of fropofol that can be used to covalently label proteins of interest to characterize fropofol's binding interactions and their contribution to general anesthetic antagonism.

In Vivo Plasticity at Hippocampal Schaffer Collateral-CA1 Synapses: Replicability of the LTP Response and Pharmacology in the Long-Evans Rat.

Broad issues associated with non-replicability have been described in experimental pharmacological and behavioral cognitive studies. Efforts to prevent biases that contribute to non-replicable scientific protocols and to improve experimental rigor for reproducibility are increasingly seen as a basic requirement for the integrity of scientific research. Synaptic plasticity, encompassing long-term potentiation (LTP), is believed to underlie mechanisms of learning and memory. The present study was undertaken in Long-Evans (LE) rats, a strain of rat commonly used in cognitive behavioral tests, to (1) compare three LTP tetanisation protocols, namely, the high-frequency stimulation (HFS), the theta-burst stimulation (TBS), and the paired-pulse facilitation (PPF) at the Schaffer collateral-CA1 stratum radiatum synapse and to (2) assess sensitivity to acute pharmacology. Results: (1) When compared to Sprague-Dawley (SD) rats, the HFS using a stimulus intensity of 50% of the maximum slope obtained from input/output (I/O) curves elicited lower and higher thresholds of synaptic plasticity responses in SD and LE rats, respectively. The 2-train TBS protocol significantly enhanced the LTP response in LE rats over the 5- and 10-train TBS protocols in both strains, and the 5 × TBS protocol inducing a subthreshold LTP response was used in subsequent pharmacological studies in LE rats. The PPF protocol, investigating the locus of the LTP response, showed no difference for the selected interstimulus intervals. (2) Scopolamine, a nonspecific muscarinic antagonist, had a subtle effect, whereas donepezil, an acetylcholinesterase inhibitor, significantly enhanced the LTP response, demonstrating the sensitivity of the TBS protocol to enhanced cholinergic tone. MK-801, a noncompetitive N-methyl-D-aspartate (NMDA) antagonist, significantly reduced LTP response, while memantine, another NMDA antagonist, had no effect on LTP response, likely associated with a weaker TBS protocol. PQ10, a phosphodiesterase-10 inhibitor, significantly enhanced the TBS-induced LTP response, but did not change the PPF response. Overall, the results confirm the strain-dependent differences in the form of synaptic plasticity, replicate earlier plasticity results, and report effective protocols that generate a relatively subthreshold margin of LTP induction and maintenance, which are suitable for pharmacology in the LE rat strain mainly used in cognitive studies.

Glomerulonephritis With Positive Anti-Glomerular Basement Membrane Antibodies Following Alemtuzumab Treatment.

Presentation A 28 year old female presented to the emergency department with a one week history of headache, vomiting and diaphoresis. Creatinine on admission was 492 and urinalysis revealed blood and protein. This was 5 months after a second infusion of Alemtuzumab, for treatment of highly active relapsing remitting multiple sclerosis. Diagnosis Anti-glomerular basement membrane disease was diagnosed after a vasculitic screen was sent for suspected glomerulonephritis. Treatment Unfortunately despite early diagnosis and immunosuppressive treatment, the patient progressed to end stage kidney failure. Conclusion It is important to maintain a high index of suspicion and test for anti-GBM disease in patients receiving alemtuzumab who develop acute renal failure.

Human lung extracellular matrix hydrogels resemble the stiffness and viscoelasticity of native lung tissue.

Chronic lung diseases such as idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) are associated with changes in extracellular matrix (ECM) composition and abundance affecting the mechanical properties of the lung. This study aimed to generate ECM hydrogels from control, severe COPD [Global Initiative for Chronic Obstructive Lung Disease (GOLD) IV], and fibrotic human lung tissue and evaluate whether their stiffness and viscoelastic properties were reflective of native tissue. For hydrogel generation, control, COPD GOLD IV, and fibrotic human lung tissues were decellularized, lyophilized, ground into powder, porcine pepsin solubilized, buffered with PBS, and gelled at 37°C. Rheological properties from tissues and hydrogels were assessed with a low-load compression tester measuring the stiffness and viscoelastic properties in terms of a generalized Maxwell model representing phases of viscoelastic relaxation. The ECM hydrogels had a greater stress relaxation than tissues. ECM hydrogels required three Maxwell elements with slightly faster relaxation times (τ) than that of native tissue, which required four elements. The relative importance (Ri) of the first Maxwell element contributed the most in ECM hydrogels, whereas for tissue the contribution was spread over all four elements. IPF tissue had a longer-lasting fourth element with a higher Ri than the other tissues, and IPF ECM hydrogels did require a fourth Maxwell element, in contrast to all other ECM hydrogels. This study shows that hydrogels composed of native human lung ECM can be generated. Stiffness of ECM hydrogels resembled that of whole tissue, while viscoelasticity differed.

Protein three-dimensional structures at the origin of life.

Proteins are relatively easy to synthesize, compared to nucleic acids and it is likely that there existed a stage prior to the RNA world which can be called the protein world. Some of the three-dimensional (3D) peptide structures in these proteins have, we argue, been conserved since then and may constitute the oldest biological relics in existence. We focus on 3D peptide motifs consisting of up to eight or so amino acid residues. The best known of these is the 'nest', a three- to seven-residue protein motif, which has the function of binding anionic atoms or groups of atoms. Ten per cent of amino acids in typical proteins belong to a nest, so it is a common motif. A five-residue nest is found as part of the well-known P-loop that is a recurring feature of many ATP or GTP-binding proteins and it has the function of binding the phosphate part of these ligands. A synthetic hexapeptide, ser-gly-ala-gly-lys-thr, designed to resemble the P-loop, has been shown to bind inorganic phosphate. Another type of nest binds iron-sulfur centres. A range of other simple motifs occur with various intriguing 3D structures; others bind cations or form channels that transport potassium ions; other peptides form catalytically active haem-like or sheet structures with certain transition metals. Amyloid peptides are also discussed. It now seems that the earliest polypeptides were far from being functionless stretches, and had many of the properties, both binding and catalytic, that might be expected to encourage and stabilize simple life forms in the hydrothermal vents of ocean depths.

Azi-medetomidine: Synthesis and Characterization of a Novel α2 Adrenergic Photoaffinity Ligand.

Agonists at the α2 adrenergic receptor produce sedation, increase focus, provide analgesia, and induce centrally mediated hypotension and bradycardia, yet neither their dynamic interactions with adrenergic receptors nor their modulation of neuronal circuit activity is completely understood. Photoaffinity ligands of α2 adrenergic agonists have the potential both to capture discrete moments of ligand-receptor interactions and to prolong naturalistic drug effects in discrete regions of tissue in vivo. We present here the synthesis and characterization of a novel α2 adrenergic agonist photolabel based on the imidazole medetomidine called azi-medetomidine. Azi-medetomidine shares protein association characteristics with its parent compound in experimental model systems and by molecular dynamics simulation of interactions with the α2A adrenergic receptor. Azi-medetomidine acts as an agonist at α2A adrenergic receptors, and produces hypnosis in Xenopus laevis tadpoles. Azi-medetomidine competes with the α2 agonist clonidine at α2A adrenergic receptors, which is potentiated by photolabeling, and azi-medetomidine labels moieties on the α2A adrenergic receptor as determined by mass spectrometry in a manner consistent with a simulated model. This novel α2 adrenergic agonist photolabel can serve as a powerful tool for in vitro and in vivo investigations of adrenergic signaling.

Revisiting the ß-Lactams for Tuberculosis Therapy with a Compound-Compound Synthetic Lethality Approach.

The suboptimal effectiveness of ß-lactam antibiotics against Mycobacterium tuberculosis has hindered the utility of this compound class for tuberculosis treatment. However, the results of treatment with a second-line regimen containing meropenem plus a ß-lactamase inhibitor were found to be encouraging in a case study of extensively drug-resistant tuberculosis (M. C. Payen, S. De Wit, C. Martin, R. Sergysels, et al., Int J Tuberc Lung Dis 16:558-560, 2012, https://doi.org/10.5588/ijtld.11.0414). We hypothesized that the innate resistance of M. tuberculosis to ß-lactams is mediated in part by noncanonical accessory proteins that are not considered the classic targets of ß-lactams and that small-molecule inhibitors of those accessory targets might sensitize M. tuberculosis to ß-lactams. In this study, we screened an NIH small-molecule library for the ability to sensitize M. tuberculosis to meropenem. We identified six hit compounds, belonging to either the N-arylindole or benzothiophene chemotype. Verification studies confirmed the synthetic lethality phenotype for three of the N-arylindoles and one benzothiophene derivative. The latter was demonstrated to be partially bioavailable via oral administration in mice. Structure-activity relationship studies of both structural classes identified analogs with potent antitubercular activity, alone or in combination with meropenem. Transcriptional profiling revealed that oxidoreductases, MmpL family proteins, and a 27-kDa benzoquinone methyltransferase could be the targets of the N-arylindole potentiator. In conclusion, our compound-compound synthetic lethality screening revealed novel small molecules that were capable of potentiating the action of meropenem, presumably via inhibition of the innate resistance conferred by ß-lactam accessory proteins. ß-Lactam compound-compound synthetic lethality may be an alternative approach for drug-resistant tuberculosis.