Measuring Ion Channels on Solid Supported Membranes

Application of solid supported membranes (SSMs) for the functional investigation of ion channels is presented. SSM-based electrophysiology, which has been introduced previously for the investigation of active transport systems, is expanded for the analysis of ion channels. Membranes or liposomes containing ion channels are adsorbed to an SSM and a concentration gradient of a permeant ion is applied. Transient currents representing ion channel transport activity are recorded via capacitive coupling. We demonstrate the application of the technique to liposomes reconstituted with the peptide cation channel gramicidin, vesicles from native tissue containing the nicotinic acetylcholine receptor, and membranes from a recombinant cell line expressing the ionotropic P2X2 receptor. It is shown that stable ion gradients, both inside as well as outside directed, can be applied and currents are recorded with an excellent signal/noise ratio. For the nicotinic acetylcholine receptor and the P2X2 receptor excellent assay quality factors of Z′ = 0.55 and Z′ = 0.67, respectively, are obtained. This technique opens up new possibilities in cases where conventional electrophysiology fails like the functional characterization of ion channels from intracellular compartments. It also allows for robust fully automatic assays for drug screening

Breaking Azacalix[4]arenes into Induline Derivatives

Tetraamino-tetranitro-azacalixarene 5 is at the crossroad of two different families of compounds depending on the conditions and the agent used to reduce the NO 2 groups: (1) azacalixphyrin 7 in neutral medium, or (2) phenazinium of type 8 in acidic medium. The key role of the N-substituted amino functions at the periphery is highlighted by investigating octaaminoazacalixarene as a model compound, and by using the corresponding tetrahydroxy-tetranitro-azacalixarene 15 as a precursor, which behaves differently

Insights into Extended Coupled Polymethines through the Investigation of Dual UV-to-NIR Acidochromic Switches Based on Heptamethine-Oxonol Dyes

A series of heptamethine-oxonol dyes featuring different heterocyclic end groups were designed with the aim to explore structure-properties relationships in π-extend coupled polymethines. These dyes can be stabilised under three different protonation states, affording dicationic derivatives with an aromatic core, cationic heptamethines, and zwitterionic bis-cyanine forms. The variation of the end groups directly impacts the absorption and emission properties and mostly controls reaching either a colourless neutral dispirocyclic species or near-infrared zwitterions. The acidochromic switching between the three states involves profound electronic rearrangements leading to notable shifts of their optical properties that were investigated using a parallel experiment-theory approach, providing a comprehensive description of these unique systems

Downhill running increases markers of muscle damage and impairs the maximal voluntary force production as well as the late phase of the rate of voluntary force development

International audiencePurpose : to examined the time-course of the early and late phase of the rate of voluntary force development (RVFD) andmuscle damage markers after downhill running.Methods : ten recreational runners performed a 30-min downhill run at 10 km h−1 and −20% (−11.3°) on a motorized treadmill. At baseline and each day up to 4 days RVFD, knee extensors maximum voluntary isometric force (MVIC), serum creatine kinase (CK) concentration, quadriceps swelling, and soreness were assessed. The early (0–50 ms) and late (100–200 ms) phase of the RVFD, as well as the force developed at 50 and 200 ms, were also determined.Results : MVIC showed moderate decrements (p 0.05). Force at 50 ms and the earlyphase were not impaired (p > 0.05). Conversely, force at 200 ms and the late phase showed moderate decrements (p 0.05). CK concentration, quadriceps swelling, and soreness increased(p 0.05).Conclusion : downhill running affected the knee extensors RVFD late but not early phase. The RVFD late phase may be usedas an additional marker of muscle damage in trail running

Optochemical control of genetically engineered neuronal nicotinic acetylcholine receptors

International audienceAdvances in synthetic chemistry, structural biology, molecular modelling and molecular cloning have enabled the systematic functional manipulation of transmembrane proteins. By combining genetically manipulated proteins with light-sensitive ligands, innately `blind' neurobiological receptors can be converted into photoreceptors, which allows them to be photoregulated with high spatiotemporal precision. Here, we present the optochemical control of neuronal nicotinic acetylcholine receptors (nAChRs) with photoswitchable tethered agonists and antagonists. Using structure-based design, we produced heteromeric alpha 3 beta 4 and alpha 4 beta 2 nAChRs that can be activated or inhibited with deep-violet light, but respond normally to acetylcholine in the dark. The generation of these engineered receptors should facilitate investigation of the physiological and pathological functions of neuronal nAChRs and open a general pathway to photosensitizing pentameric ligand-gated ion channels

Tris‐benzo[cd]indole Cyanine Enables the NIR‐photosensitized Radical and Thiol‐ene Polymerizations at 940 nm

International audienceA near‐infrared‐absorbing heptamethine (HM+) incorporating three bulky benzo[cd]indole heterocycles was designed to efficiently prevent self‐aggregation of the dye, which results in a strong enhancement of its photoinitiating reactivity as compared to a parent bis‐benzo[cd]indole heptamethine (HMCl+) used as a reference system. In this context, we highlight an efficient free‐radical NIR‐polymerization up to a 100% acrylates C=C bonds conversion even under air conditions. Such an important initiating performance was obtained by incorporating our NIR‐sensitizer into a three‐component system leading to its self‐regeneration. This original photoredox cycle was thoroughly investigated through the identification of each intermediary species using EPR spectroscopy

Antineutrophil cytoplasmic antibody-associated vasculitides and IgG4-related disease: A new overlap syndrome

Objective Atypical manifestations have been described in patients with ANCA-associated vasculitides (AAV), such as pachymeningitis, orbital mass or chronic periaortitis. Because these manifestations have been associated to the spectrum of IgG4-related disease (IgG4-RD), we hypothesized that both diseases could overlap. Methods We conducted a European retrospective multicenter observational study including patients fulfilling ACR and Chapel Hill criteria for AAV and IgG4-RD Comprehensive Diagnostic Criteria. Results Eighteen patients were included (median age 55.5 years, 13 men). AAV and IgG4-RD were diagnosed concomitantly in 13/18 (72%) patients; AAV preceded IgG4-RD in 3/18 (17%) while IgG4-RD preceded AAV in 2/18 (11%). AAV diagnoses included granulomatosis with polyangiitis in 14 (78%), microscopic polyangiitis in 3 (17%), and eosinophilic granulomatosis with polyangiitis in one case. IgG4-RD diagnosis included definite IgG4-RD in 5 (28%) cases, probable IgG4-RD in 5 (28%) and possible IgG4-RD in 8 (44%). IgG4-RD manifestations were chronic periaortitis in 9/18 (50%) patients, orbital mass and tubulointerstitial nephritis in 4 (22%) cases, prevertebral fibrosis in 3 (17%), pachymeningitis and autoimmune pancreatitis in 2 (11%) cases. Patients required median number of 2 (range 0–4) lines of immunosuppressants in combination with glucocorticoids. During the follow-up (median 49,8 months, range 17,25–108 months), AAV manifestations relapsed in 10/18 (56%) cases and IgG4-RD lesions in 5/18 (28%). When used, mainly for relapses, rituximab showed response in all cases. Conclusion AAV and IgG4-RD may overlap. Clinicians should consider that atypical manifestations during AAV could be related to IgG4-RD rather than to refractory granulomatous or vasculitic lesions.status: publishe

Antineutrophil cytoplasmic antibody-associated vasculitides and IgG4-related disease: A new overlap syndrome

Abstract OBJECTIVE: Atypical manifestations have been described in patients with ANCA-associated vasculitides (AAV), such as pachymeningitis, orbital mass or chronic periaortitis. Because these manifestations have been associated to the spectrum of IgG4-related disease (IgG4-RD), we hypothesized that both diseases could overlap. METHODS: We conducted a European retrospective multicenter observational study including patients fulfilling ACR and Chapel Hill criteria for AAV and IgG4-RD Comprehensive Diagnostic Criteria. RESULTS: Eighteen patients were included (median age 55.5years, 13 men). AAV and IgG4-RD were diagnosed concomitantly in 13/18 (72%) patients; AAV preceded IgG4-RD in 3/18 (17%) while IgG4-RD preceded AAV in 2/18 (11%). AAV diagnoses included granulomatosis with polyangiitis in 14 (78%), microscopic polyangiitis in 3 (17%), and eosinophilic granulomatosis with polyangiitis in one case. IgG4-RD diagnosis included definite IgG4-RD in 5 (28%) cases, probable IgG4-RD in 5 (28%) and possible IgG4-RD in 8 (44%). IgG4-RD manifestations were chronic periaortitis in 9/18 (50%) patients, orbital mass and tubulointerstitial nephritis in 4 (22%) cases, prevertebral fibrosis in 3 (17%), pachymeningitis and autoimmune pancreatitis in 2 (11%) cases. Patients required median number of 2 (range 0-4) lines of immunosuppressants in combination with glucocorticoids. During the follow-up (median 49,8months, range 17,25-108months), AAV manifestations relapsed in 10/18 (56%) cases and IgG4-RD lesions in 5/18 (28%). When used, mainly for relapses, rituximab showed response in all cases. CONCLUSION: AAV and IgG4-RD may overlap. Clinicians should consider that atypical manifestations during AAV could be related to IgG4-RD rather than to refractory granulomatous or vasculitic lesions. Copyright © 2017 Elsevier B.V. All rights reserved