331 research outputs found

    The Wall

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    Accelerando & Retardando

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    A tessellation-based colocalization analysis approach for single-molecule localization microscopy

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    International audienceMulticolor single-molecule localization microscopy (λSMLM) is a powerful technique to reveal the relative nanoscale organization and potential colocalization between different molecular species. While several standard analysis methods exist for pixel-based images, λSMLM still lacks such a standard. Moreover, existing methods only work on 2D data and are usually sensitive to the relative molecular organization, a very important parameter to consider in quantitative SMLM. Here, we present an efficient, parameter-free colocalization analysis method for 2D and 3D λSMLM using tessellation analysis. We demonstrate that our method allows for the efficient computation of several popular colocalization estimators directly from molecular coordinates and illustrate its capability to analyze multicolor SMLM data in a robust and efficient manner

    Multiple Acetylation of Pentaphenylferrocene – Synthesis and Asymmetric Reduction of 1‐Acetyl‐1â€Č,2â€Č,3â€Č,4â€Č,5â€Č‐penta(para‐acetylphenyl)ferrocene

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    The Friedel–Crafts acetylation of pentaphenylferrocene has been revisited using 1.1 equivalents of AcCl/AlCl3 in CH2Cl2 at room temperature leading to the synthesis of 1‐acetyl‐1â€Č,2â€Č,3â€Č,4â€Č,5â€Č‐pentaphenylferrocene (78 % yield). Increased quantities of reagents and longer reaction times resulted in acetylation of the phenyl groups exclusively at the para‐position, this methodology culminating in the synthesis of 1‐acetyl‐1â€Č,2â€Č,3â€Č,4â€Č,5â€Č‐penta(para‐acetylphenyl)ferrocene (32 % for a two step process). Subsequent asymmetric reduction of all six ketone functionalities with BH3·SMe2 catalysed by 60 mol‐% (S)‐CBS proceeded in 81 % yield to give (R,R,R,R,R,R)‐1‐(α‐hydroxyethyl)‐1â€Č,2â€Č,3â€Č,4â€Č,5â€Č‐penta[para‐(α‐hydroxyethyl)phenyl]ferrocene, a highly functionalised enantiopure building block for the synthesis of ligands and materials

    Cell Elasticity Determines Macrophage Function

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    Macrophages serve to maintain organ homeostasis in response to challenges from injury, inflammation, malignancy, particulate exposure, or infection. Until now, receptor ligation has been understood as being the central mechanism that regulates macrophage function. Using macrophages of different origins and species, we report that macrophage elasticity is a major determinant of innate macrophage function. Macrophage elasticity is modulated not only by classical biologic activators such as LPS and IFN-Îł, but to an equal extent by substrate rigidity and substrate stretch. Macrophage elasticity is dependent upon actin polymerization and small rhoGTPase activation, but functional effects of elasticity are not predicted by examination of gene expression profiles alone. Taken together, these data demonstrate an unanticipated role for cell elasticity as a common pathway by which mechanical and biologic factors determine macrophage function

    Stereoselective and Stereospecific Reactions of Cobalt Sandwich Complexes: Synthesis of a New Class of Single Enantiomer Bulky Planar Chiral P−N and P−P Ligands

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    Starting from (η5-acetylcyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt(I), highly enantioselective (99 % ee) (S)-CBS catalysed ketone reduction followed by stereospecific alcohol-azide exchange, azide reduction and dimethyllation gave (R)-(η5-α-N,N-dimethylaminoethylcyclopentadienyl)(η4-tetraphenylcyclobutadiene) cobalt(I) (Arthurs’ amine). This underwent highly diastereoselective cyclopalladation to give di-ÎŒ-acetate-bis-(R)-[(η5-(Sp)-2-(α-N,N-dimethylaminoethyl)cyclopentadienyl, 1-C, N)(η4-tetraphenylcyclobutadiene)cobalt(I)]dipalladium, and highly diastereoselective lithiation to give (R)-(η5-(Sp)-1-(α-N,N-dimethylaminoethyl)-2-(diphenylphosphino)cyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt(I) (PPCA) following the addition as electrophile of chlorodiphenylphosphine. This PN-ligand was converted into (R)-(η5-(Sp)-1-(α-dicyclohexylphosphinoethyl)-2-(diphenylphosphino)cyclopentadienyl)(η4-tetraphenylcyclobutadiene)cobalt(I), a PP-ligand (Rossiphos), by stereospecific amine-phosphine exchange using HPCy2. These air-stable P−N and P−P complexes are the first examples of a new class of bulky planar chiral ligands for application in asymmetric catalysis

    Epidemiology of Burkholderia cepacia Complex in Patients with Cystic Fibrosis, Canada

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    The Burkholderia cepacia complex is an important group of pathogens in patients with cystic fibrosis (CF). Although evidence for patient-to-patient spread is clear, microbial factors facilitating transmission are poorly understood. To identify microbial clones with enhanced transmissibility, we evaluated B. cepacia complex isolates from patients with CF from throughout Canada. A total of 905 isolates from the B. cepacia complex were recovered from 447 patients in 8 of the 10 provinces; 369 (83%) of these patients had genomovar III and 43 (9.6%) had B. multivorans (genomovar II). Infection prevalence differed substantially by region (22% of patients in Ontario vs. 5% in Quebec). Results of typing by random amplified polymorphic DNA analysis or pulsed-field gel electrophoresis indicated that strains of B. cepacia complex from genomovar III are the most potentially transmissible and that the B. cepacia epidemic strain marker is a robust marker for transmissibility
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