A high-throughput assay identifies molecules with antimicrobial activity against persister cells.

Introduction. Persister cells are transiently non-growing antibiotic-tolerant bacteria that cause infection relapse, and there is no effective antibiotic therapy to tackle these infections.Gap statement. High-throughput assays in drug discovery are biased towards detecting drugs that inhibit bacterial growth rather than killing non-growing bacteria. A new and simple assay to discover such drugs is needed.Aim. This study aims to develop a simple and high-throughput assay to identify compounds with antimicrobial activity against persister cells and use it to identify molecular motifs with such activity.Methodology. We quantified Staphylococcus aureus persister cells by enumeration of colony forming units after 24 h ciprofloxacin treatment. We first quantified how the cell concentration, antibiotic concentration, growth phase and presence/absence of nutrients during antibiotic exposure affected the fraction of persister cells in a population. After optimizing these parameters, we screened the antimicrobial activity of compound fragments to identify molecular structures that have activity against persister cells.Results. Exponential- and stationary-phase cultures transferred to nutrient-rich media displayed a bi-phasic time-kill curve and contained 0.001-0.07% persister cells. A short rifampicin treatment resulted in 100% persister cells for 7 h, after which cells resumed activity and became susceptible. Stationary-phase cultures displayed a low but constant death rate but ultimately resulted in similarly low survival rates as the exponential-phase cultures after 24 h ciprofloxacin treatment. The persister phenotype was only maintained in most of the population for 24 h if cells were transferred to a carbon-free minimal medium before exposure to ciprofloxacin. Keeping cells starved enabled the generation of high concentrations of S. aureus cells that tolerate 50× MIC ciprofloxacin, and we used this protocol for rapid screening for biocidal antibiotics. We identified seven compounds from four structural clusters with activity against antibiotic-tolerant S. aureus. Two compounds were moderately cytotoxic, and the rest were highly cytotoxic.Conclusion. Transferring a stationary-phase culture to a carbon-free minimal medium for antimicrobial testing is a simple strategy for high-throughput screening for new antibiotics that kill persister cells. We identified molecule fragments with such activity, but further screening is needed to identify motifs with lower general cytotoxicity.

The ClC-1 chloride channel inhibitor NMD670 improves skeletal muscle function in rat models and patients with myasthenia gravis.

Myasthenia gravis (MG) is a neuromuscular disease that results in compromised transmission of electrical signals at the neuromuscular junction (NMJ) from motor neurons to skeletal muscle fibers. As a result, patients with MG have reduced skeletal muscle function and present with symptoms of severe muscle weakness and fatigue. ClC-1 is a skeletal muscle specific chloride (Cl-) ion channel that plays important roles in regulating neuromuscular transmission and muscle fiber excitability during intense exercise. Here, we show that partial inhibition of ClC-1 with an orally bioavailable small molecule (NMD670) can restore muscle function in rat models of MG and in patients with MG. In severely affected MG rats, ClC-1 inhibition enhanced neuromuscular transmission, restored muscle function, and improved mobility after both single and prolonged administrations of NMD670. On this basis, NMD670 was progressed through nonclinical safety pharmacology and toxicology studies, leading to approval for testing in clinical studies. After successfully completing phase 1 single ascending dose in healthy volunteers, NMD670 was tested in patients with MG in a randomized, placebo-controlled, single-dose, three-way crossover clinical trial. The clinical trial evaluated safety, pharmacokinetics, and pharmacodynamics of NMD670 in 12 patients with mild MG. NMD670 had a favorable safety profile and led to clinically relevant improvements in the quantitative myasthenia gravis (QMG) total score. This translational study spanning from single muscle fiber recordings to patients provides proof of mechanism for ClC-1 inhibition as a potential therapeutic approach in MG and supports further development of NMD670.

Synthesis and biological evaluation of Esaprazole analogues showing σ1 binding and neuroprotective properties in vitro.

Esaprazole, a molecule previously acknowledged to protect against stomach and intestinal ulcers was surprisingly discovered to have neuroprotective activities and σ1 binding in vitro. A highly diverse set of Esaprazole analogues 2-5 was prepared in order to increase blood-brain barrier penetration. The analogues showed a structure-activity relationship at the σ1 receptor closely matching already published pharmacophores. Many of the analogues were shown to have neuroprotective properties in two assays using primary cultures of cortical neurons exposed to glutamate and hydrogen peroxide. However, no apparent SAR for these two assays could be developed. Metabolic stability of the analogues were also investigated and the structure of R(1) had a significant bearing on the ADME properties of the compound resulting in two series of compounds. Compounds in which R(1) was a H or acyl group had good metabolic stability in RLM but poor BBB penetration, whereas compounds where R(1) was a cyclo- or bicyclo-alkyl group had poor metabolic stability but good BBB penetration.

In situ immobilization of palladium nanoparticles in microfluidic reactors and assessment of their catalytic activity.

We report on the synthesis and characterization of catalytic palladium nanoparticles (Pd NPs) and their immobilization in microfluidic reactors fabricated from polydimethylsiloxane (PDMS). The Pd NPs were stabilized with D-biotin or 3-aminopropyltrimethoxysilane (APTMS) to promote immobilization inside the microfluidic reactors. The NPs were homogeneous with narrow size distributions between 2 and 4 nm, and were characterized by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and x-ray diffraction (XRD). Biotinylated Pd NPs were immobilized on APTMS-modified PDMS and glass surfaces through the formation of covalent amide bonds between activated biotin and surface amino groups. By contrast, APTMS-stabilized Pd NPs were immobilized directly onto PDMS and glass surfaces rich in hydroxyl groups. Fourier transform infrared spectroscopy (FT-IR) and x-ray photoelectron spectroscopy (XPS) results showed successful attachment of both types of Pd NPs on glass and PDMS surfaces. Both types of Pd NPs were then immobilized in situ in sealed PDMS microfluidic reactors after similar surface modification. The effectiveness of immobilization in the microfluidic reactors was evaluated by hydrogenation of 6-bromo-1-hexene at room temperature and one atmosphere of hydrogen pressure. An average first-run conversion of 85% and selectivity of 100% were achieved in approximately 18 min of reaction time. Control experiments showed that no hydrogenation occurred in the absence of the nanocatalysts. This system has the potential to provide a reliable tool for efficient and high throughput evaluation of catalytic NPs, along with assessment of intrinsic kinetics.

Discovery of non-peptidergic MrgX1 and MrgX2 receptor agonists and exploration of an initial SAR using solid-phase synthesis.

A class of small molecules displaying comparable activities with peptide ligands BAM22 and corticostatin-14 at both the human and rhesus monkey MrgX1 and MrgX2 receptors, respectively, was discovered. A comparative study to compare solid-phase and solution-phase chemistries for the efficient synthesis of the active class, tetracyclic benzimidazoles, was undertaken. The solid-phase chemistry was found to be superior both for the synthesis of analogs and for the synthesis of gram quantities.

4-iodophenyl isothiocyanate: a neuroprotective compound.

PURPOSE: Naturally occurring isothiocyanates (ITCs) are known to possess chemopreventive and neuroprotective properties. Our objective was to study the synthetic ITC 4-iodophenyl isothiocyanate (4-IPITC) in different models of neurodegeneration. METHODS: In vitro, we exposed primary cortical neurons to various insults such as excessive glutamate exposure, oxygen-glucose deprivation, oxidative stress and 1-methyl-phenylpyridinium (MPP+). In vivo, experimental autoimmune encephalomyelitis (EAE) was induced in dark agouti rats treated with 4-IPITC in 3 different concentrations (10, 20 and 40 mg/kg), orally for 28 days. In a Parkinson's model, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was injected in mice pretreated with 4-IPITC (5 mg/kg, orally) for 1 week. Nest building behavior at day 1, 3 and 6 after MPTP injection was assessed along with dopamine and metabolites, and tyrosine hydroxylase (TH) staining on termination day 6. RESULTS: 4-IPITC successfully reduced cell death in all in vitro assays. Moreover, in two independent neurite outgrowth assays the compound showed neurotrophic properties. In the EAE study, 4-IPITC significantly delayed the day of onset and decreased the cumulative EAE score. Although the number of animals in this MPTP study was limited, 4-IPITC showed potential for dampening toxicity. CONCLUSIONS: Taken together, our in vitro findings suggest robust neuroprotective and neurotrophic properties of 4-IPITC, which was confirmed in two in vivo models of neurodegeneration.

Is the 'driving test' a robust quality indicator of colonoscopy performance?

Colorectal cancer is a major cause of death in the western world and is currently the second commonest cause of death from malignant disease in the UK. Recently a "driving test" for colonoscopists wishing to take part in the National Health Service Bowel Cancer Screening Program has been introduced, with the aim of improving quality in colonoscopy. We describe the accreditation process and have reviewed the published evidence for its use. We compared this method of assessment to what occurs in other developed countries. To the authors' knowledge no other countries have similar methods of assessment of practicing colonoscopists, and instead use critical evaluation of key quality criteria. The UK appears to have one of the most rigorous accreditation processes, although this still has flaws. The published evidence suggests that the written part of the accreditation is not a good discriminating test and it needs to be improved or abandoned. Further work is needed on the best methods of assessing polypectomy skills. Rigorous systems need to be in place for the colonoscopist who fails the assessment.

Discovery of selective nonpeptidergic neuropeptide FF2 receptor agonists.

We report the discovery and initial characterization of a novel class of selective NPFF2 agonists. HTS screening using R-SAT, a whole cell based functional assay, identified a class of aryliminoguanidines as NPFF1 and NPFF2 ligands. Subsequent optimization led to molecules exhibiting selective NPFF2 agonistic activity. Systemic administration showed that selective NPFF2 agonists (1 and 3) are active in various pain models in vivo, whereas administration of a nonselective NPFF1 and NPFF2 agonist (9) increases sensitivity to noxious and non-noxious stimuli.