Publications by authors named "N Leclerc"

120 Publications

Redox-Responsive Host-Guest Association between γ-Cyclodextrin and Mixed-Metal Keggin-Type Polyoxometalates.

Inorg Chem 2021 May 29;60(10):7433-7441. Epub 2021 Apr 29.

Institut Lavoisier de Versailles, UMR 8180 CNRS, UVSQ, Université Paris-Saclay, Versailles 78035, France.

The complexation of Keggin-type polyoxometalates (POMs) with γ-cyclodextrin (γ-CD) leads to supramolecular inclusion assemblies in aqueous solution driven by a chaotropic effect. The strength of the interaction between γ-CD and oxidized or one-electron reduced POMs in a series of molybdenum and vanadium monosubstituted phospho- and silico-tungstates, [XWMO] Keggin-type anions where X = P or Si and M = Mo or V, has been evaluated by isothermal titration calorimetry (ITC), NMR spectroscopy, and cyclic voltammetry. Such a study reveals that the host-guest binding constant increases strongly with the decrease of the global ionic charge of the POM unit. There is an almost one magnitude order of variation in per charge unit, where falls down from about 10 M to values close to zero as ionic charge varies from 3- to 6-. Such POMs with molybdenum and vanadium addenda offer the possibility of tuning the host-guest association strength by the simple addition/removal of one electron to POMs, opening a new avenue for the design of smart materials through redox stimuli.
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http://dx.doi.org/10.1021/acs.inorgchem.1c00724DOI Listing
May 2021

Evaluating the acceptance of ambient assisted living technology (AALT) in rehabilitation: A scoping review.

Int J Med Inform 2021 06 14;150:104461. Epub 2021 Apr 14.

Centre for Interdisciplinary Research in Rehabilitation of the Greater Montreal (CRIR), Institut universitaire sur la réadaptation en déficience physique de Montréal (IURDPM), 6363 Hudson Road, Montreal, Quebec, H3S 1M9, Canada; School of Rehabilitation, Faculty of Medicine, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, Québec, H3C 3J7, Canada.

Objectives: Ambient assisted living technologies (AALTs) are being used to help community-dwelling older adults (OAs) age in place. Although many AALT are available, their acceptance (perceived usefulness, ease of use, intention to use and actual usage) is needed to improve their design and impact. This study aims to 1) identify AALTs that underwent an acceptance evaluation in rehabilitation contexts, 2) identify methodological tools and approaches to measure acceptance in ambient assisted living (AAL) in rehabilitation research, and 3) summarize AALT acceptance results in existing rehabilitation literature with a focus on peer-reviewed scientific articles.

Methods: A scoping review was conducted in the following databases: Medline, Embase, Cinahl, and PsycInfo, following the Arksey and O'Malley framework (2009). Four acceptance attributes were extracted: 'user acceptance', 'perceived usefulness', 'ease of use', and 'intention to use'. Data regarding AALT, participants, acceptance evaluation methods and results were extracted.

Results: A total of 21 articles were included among 634 studies retrieved from the literature. We identified 51 AALTs dedicated to various rehabilitation contexts, most of which focused on monitoring OAs' activities and environmental changes. Acceptance of AALT was evaluated using interviews, questionnaires, focus groups, informal feedback, observation, card sort tasks, and surveys. Although OAs intend to use - or can perceive the usefulness of - AALTs, they are hesitant to accept the technology and have concerns about its adoption.

Discussion And Conclusions: The assessment of AALT acceptance in contexts of rehabilitation requires more comprehensive and standardized methodologies. The use of mixed-methods research is encouraged to cover the needs of particular studies. The timing of acceptance assessment should be considered throughout technology development phases to maximize AALT implementation.
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http://dx.doi.org/10.1016/j.ijmedinf.2021.104461DOI Listing
June 2021

Ultra-Narrow-Band NIR Photomultiplication Organic Photodetectors Based on Charge Injection Narrowing.

J Phys Chem Lett 2021 Mar 16;12(11):2937-2943. Epub 2021 Mar 16.

Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University, Beijing 100044, P. R. China.

Ultra-narrow-band NIR photomultiplication organic photodetectors (PM-OPDs) were realized in ITO/PEDOT:PSS/active layers/Al based on an interfacial-trap-induced charge injection narrowing (CIN) concept. The rather less Bod Ethex-Hex (BEH) is imbedded in a polymer donor matrix to form large amounts of isolated electron traps. Trapped electrons in BEH close to an Al electrode will enforce hole-tunneling injection induced by interfacial band bending, resulting in a photomultiplication phenomenon. PM-OPDs with P3HT:BEH as the active layer exhibit a narrow response peak at 850 nm with a full-width at half-maximum (fwhm) of 27 nm as well as a rather weak response from 650 to 800 nm. The EQE of 29 700% at 850 nm was achieved in PM-OPDs by incorporating 0.02 wt % of FTCNNQ under -13 V of applied voltage. The rejection ratio (RR) of the optimized PM-OPDs with FTCNNQ is 11 for EQE/EQE and 10 for EQE/EQE, respectively. An EQE of 15 300% at 850 nm was achieved in the ternary PM-OPDs under -13 V of applied voltage, with markedly enhanced RRs of 44 for EQE/EQE and 30 for EQE/EQE.
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http://dx.doi.org/10.1021/acs.jpclett.1c00330DOI Listing
March 2021

Similarities and Differences in the Pattern of Tau Hyperphosphorylation in Physiological and Pathological Conditions: Impacts on the Elaboration of Therapies to Prevent Tau Pathology.

Front Neurol 2020 7;11:607680. Epub 2021 Jan 7.

Research Center of the University of Montreal Hospital (CRCHUM), Montréal, QC, Canada.

Tau protein, a neuronal microtubule-associated protein, becomes hyperphosphorylated in several neurodegenerative diseases called tauopathies. Hyperphosphorylation of tau is correlated to its redistribution from the axon to the somato-dendritic compartment at early stages of tauopathies. Interestingly, tau hyperphosphorylation begins in different regions of the brain in each tauopathy. In some regions, both neurons and glial cells develop tau hyperphosphorylation. Tau hyperphosphorylation is also observed in physiological conditions such as hibernation and brain development. In the first section of present article, we will review the spatiotemporal and cellular distribution of hyperphosphorylated tau in the most frequent tauopathies. In the second section, we will compare the pattern of tau hyperphosphorylation in physiological and pathological conditions and discuss the sites that could play a pivotal role in the conversion of non-toxic to toxic forms of hyperphosphorylated tau. Furthermore, we will discuss the role of hyperphosphorylated tau in physiological and pathological conditions and the fact that tau hyperphosphorylation is reversible in physiological conditions but not in a pathological ones. In the third section, we will speculate how the differences and similarities between hyperphosphorylated tau in physiological and pathological conditions could impact the elaboration of therapies to prevent tau pathology. In the fourth section, the different therapeutic approaches using tau as a direct or indirect therapeutic target will be presented.
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http://dx.doi.org/10.3389/fneur.2020.607680DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817657PMC
January 2021

Clearance of intracellular tau protein from neuronal cells via VAMP8-induced secretion.

J Biol Chem 2020 12;295(51):17827-17841

Research Center of the University of Montreal Hospital (CRCHUM), Montréal, Canada; Département de Neurosciences, Faculté de Médecine, Université de Montréal, Montréal, Canada. Electronic address:

In Alzheimer's disease (AD), tau, a microtubule-associated protein (MAP), becomes hyperphosphorylated, aggregates, and accumulates in the somato-dendritic compartment of neurons. In parallel to its intracellular accumulation in AD, tau is also released in the extracellular space, as revealed by its increased presence in cerebrospinal fluid (CSF). Consistent with this, recent studies, including ours, have reported that neurons secrete tau, and several therapeutic strategies aim to prevent the intracellular tau accumulation. Previously, we reported that late endosomes were implicated in tau secretion. Here, we explore the possibility of preventing intracellular tau accumulation by increasing tau secretion. Using neuronal models, we investigated whether overexpression of the vesicle-associated membrane protein 8 (VAMP8), an R-SNARE found on late endosomes, could increase tau secretion. The overexpression of VAMP8 significantly increased tau secretion, decreasing its intracellular levels in the neuroblastoma (N2a) cell line. Increased tau secretion by VAMP8 was also observed in murine hippocampal slices. The intracellular reduction of tau by VAMP8 overexpression correlated to a decrease of acetylated tubulin induced by tau overexpression in N2a cells. VAMP8 staining was preferentially found on late endosomes in N2a cells. Using total internal reflection fluorescence (TIRF) microscopy, the fusion of VAMP8-positive vesicles with the plasma membrane was correlated to the depletion of tau in the cytoplasm. Finally, overexpression of VAMP8 reduced the intracellular accumulation of tau mutants linked to frontotemporal dementia with parkinsonism and α-synuclein by increasing their secretion. Collectively, the present data indicate that VAMP8 could be used to increase tau and α-synuclein clearance to prevent their intracellular accumulation.
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http://dx.doi.org/10.1074/jbc.RA120.013553DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7762943PMC
December 2020
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