Visualization of cell microtubules in their native state.

BACKGROUND INFORMATION Over the past decades, cryo-electron microscopy of vitrified specimens has yielded a detailed understanding of the tubulin and microtubule structures of samples reassembled in vitro from purified components. However, our knowledge of microtubule structure in vivo remains limited by the chemical treatments commonly used to observe cellular architecture using electron microscopy. RESULTS We used cryo-electron microscopy and cryo-electron tomography of vitreous sections to investigate the ultrastructure of microtubules in their cellular context. Vitreous sections were obtained from organotypic slices of rat hippocampus and from Chinese-hamster ovary cells in culture. Microtubules revealed their protofilament ultrastructure, polarity and, in the most favourable cases, molecular details comparable with those visualized in three-dimensional reconstructions of microtubules reassembled in vitro from purified tubulin. The resolution of the tomograms was estimated to be approx. 4 nm, which enabled the detection of luminal particles of approx. 6 nm in diameter inside microtubules. CONCLUSIONS The present study provides a first step towards a description of microtubules, in addition to other macromolecular assemblies, in an unperturbed cellular context at the molecular level. As the resolution appears to be similar to that obtainable with plunge-frozen samples, it should allow for the in vivo identification of larger macromolecular assemblies in vitreous sections of whole cells and tissues.

A Randomized Comparison of Reservoir-Based Polymer-Free Amphilimus-Eluting Stents Versus Everolimus-Eluting Stents With Durable Polymer in Patients With Diabetes Mellitus: The RESERVOIR Clinical Trial.

OBJECTIVES The aim of this study was to compare the efficacy of amphilimus-eluting stents (AES) with that of everolimus-eluting stents (EES) in patients with diabetes mellitus (DM). BACKGROUND The AES is a polymer-free drug-eluting stent that elutes sirolimus formulated with an amphiphilic carrier from laser-dug wells. This technology could be associated with a high efficacy in patients with DM. METHODS This was a multicenter, randomized, noninferiority trial. Patients with DM medically treated with oral glucose-lowering agents or insulin and de novo coronary lesions were randomized in a 1:1 fashion to AES or EES. The primary endpoint was the neointimal (NI) volume obstruction assessed by optical coherence tomography at 9-month follow-up. RESULTS A total of 116 lesions in 112 patients were randomized. Overall, 40% were insulin-treated patients, with a median HbA1c of 7.3% (interquartile range: 6.7% to 8.0%). The primary endpoint, NI volume obstruction, was 11.97 ± 5.94% for AES versus 16.11 ± 18.18% for EES, meeting the noninferiority criteria (p = 0.0003). Pre-specified subgroup analyses showed a significant interaction between stent type and glycemic control (p = 0.02), with a significant reduction in NI hyperplasia in the AES group in patients with the higher HbA1c (p = 0.03). By quantitative coronary angiography, in-stent late loss was 0.14 ± 0.24 for AES versus 0.24 ± 0.57 mm for EES (p = 0.27), with a larger minimal lumen diameter at follow-up for AES (p = 0.02), mainly driven by 2 cases of occlusive restenosis in the EES group. CONCLUSIONS AES are noninferior to EES for the coronary revascularization of patients with DM. These results suggest a high efficacy of the AES and may support the potential benefit of this stent in patients with DM. (A Randomized Comparison of Reservoir-Based Polymer-Free Amphilimus-Eluting Stents Versus Everolimus-Eluting Stents With Durable Polymer in Patients With Diabetes Mellitus [RESERVOIR]; NCT01710748).

How exclusive is assembly democracy? Citizens assembly and ballot participation compared

This paper analyses the difference between two specific forms of citizens’ involvements, namely whether a vote is cast by ballot or in a citizens’ assembly in which people gather in town halls to decide legislative questions in a deliberative manner. We show both theoretically and empirically how citizens’ assemblies and decisions at the ballot box substantially differ not only in terms of their underlying model of democracy, but also in their structural conditions and, thus, with respect to the social inequality of participation. We test our hypotheses in a Bayesian multilevel framework using real participation data collected from 15 political decisions made in a Swiss commune. Our results show that citizens’ assemblies are not only characterised by lower participation rates, but also by a particular composition of the electorate. While citizens’ assemblies are more equal regarding income groups, ballots favour a more equitable participation in terms of gender and age.

Ion channel macromolecular complexes in cardiomyocytes: roles in sudden cardiac death.

The movement of ions across specific channels embedded on the membrane of individual cardiomyocytes is crucial for the generation and propagation of the cardiac electric impulse. Emerging evidence over the past 20 years strongly suggests that the normal electric function of the heart is the result of dynamic interactions of membrane ion channels working in an orchestrated fashion as part of complex molecular networks. Such networks work together with exquisite temporal precision to generate each action potential and contraction. Macromolecular complexes play crucial roles in transcription, translation, oligomerization, trafficking, membrane retention, glycosylation, post-translational modification, turnover, function, and degradation of all cardiac ion channels known to date. In addition, the accurate timing of each cardiac beat and contraction demands, a comparable precision on the assembly and organizations of sodium, calcium, and potassium channel complexes within specific subcellular microdomains, where physical proximity allows for prompt and efficient interaction. This review article, part of the Compendium on Sudden Cardiac Death, discusses the major issues related to the role of ion channel macromolecular assemblies in normal cardiac electric function and the mechanisms of arrhythmias leading to sudden cardiac death. It provides an idea of how these issues are being addressed in the laboratory and in the clinic, which important questions remain unanswered, and what future research will be needed to improve knowledge and advance therapy.