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Fonctionnalisation de nanoparticules magnétiques par des peptides cationiques : vers un accès au cytosol
No full textMagnetic nanoparticles (MNPs) are a promising class of functional nanomaterials in the biomedical field for various applications such as magnetic manipulation and magnetic hyperthermia. However, a major limitation of these approaches is their endosomal entrapment after internalization by the endocytosis pathway, where the ease of magnetic manipulation is restricted. The objective of this project was to improve the access of MNPs to the cytosol by functionalizing them with cationic peptides. Arg9 is a classical cell-penetrating peptide (CPP), able to enter cells by direct translocation, a transient perturbation of the plasma membrane which allows CPPs to reach the cytosol. On the other hand, it has been demonstrated that sequences rich in histidine residues promote endosomal escape, probably by proton sponge effect. MNPs used are iron oxide nanoparticles coated with silica γ-Fe2O3@ SiO2 allowing their surface to be functionalized by cationic peptides using click chemistry. First, the synthesis and characterization of peptides and core-shell nanoparticles was carried out, then the functionalization of these nanoparticles by peptides. The internalization of the nanoparticles in cells was then studied, using confocal fluorescence microscopy combined with calcein leakage experiments, and transmission electron microscopy. It was shown that the grafting onto nanoparticles of peptides rich in histidine promotes their access to the cytosol.Les nanoparticules magnétiques (NPM) sont une classe prometteuse de nanomatériaux fonctionnels dans le domaine biomédical pour diverses applications telles que la thérapie anticancéreuse par hyperthermie ou la manipulation magnétique intracellulaire. Cependant, une limitation majeure de ces approches est leur piégeage endosomal après internalisation par la voie d'endocytose, conduisant à une chute de leur pouvoir chauffant et réduisant les possibilités de ciblage intracellulaire. L’objectif de ce projet était d'améliorer l'accès des NPM au cytosol en les fonctionnalisant avec des peptides cationiques. Arg9 est un peptide vecteur (cell-penetrating peptides, CPP) classique, capable de pénétrer dans les cellules par translocation directe, une perturbation transitoire de la membrane plasmique permettant d'atteindre le cytosol. D'autre part, il a été démontré que des séquences riches en résidus histidine favorisent l'échappement endosomal, probablement par effet d'éponge à protons. Les NPM utilisées sont des nanoparticules d’oxydes de fer enrobées de silice γ-Fe2O3@SiO2 permettant de fonctionnaliser leur surface par les peptides cationiques en utilisant la chimie click. Dans un premier temps, la synthèse et caractérisation des peptides et des nanoparticules cœur-coquilles ont été réalisées, puis la fonctionnalisation de ces nanoparticules par les peptides. L’internalisation des nanoparticules dans les cellules a ensuite été étudiée, par microscopie confocale combinée à des expériences de fuite de calcéine, et par microscopie électronique à transmission. Il a ainsi pu être montré que le greffage sur les nanoparticules de peptides riches en histidine permet de favoriser leur accès au cytosol
Functionalisation of magnetic nanoparticles by cationic peptides : towards cytosol access
No full textLes nanoparticules magnétiques (NPM) sont une classe prometteuse de nanomatériaux fonctionnels dans le domaine biomédical pour diverses applications telles que la thérapie anticancéreuse par hyperthermie ou la manipulation magnétique intracellulaire. Cependant, une limitation majeure de ces approches est leur piégeage endosomal après internalisation par la voie d'endocytose, conduisant à une chute de leur pouvoir chauffant et réduisant les possibilités de ciblage intracellulaire. L’objectif de ce projet était d'améliorer l'accès des NPM au cytosol en les fonctionnalisant avec des peptides cationiques. Arg9 est un peptide vecteur (cell-penetrating peptides, CPP) classique, capable de pénétrer dans les cellules par translocation directe, une perturbation transitoire de la membrane plasmique permettant d'atteindre le cytosol. D'autre part, il a été démontré que des séquences riches en résidus histidine favorisent l'échappement endosomal, probablement par effet d'éponge à protons. Les NPM utilisées sont des nanoparticules d’oxydes de fer enrobées de silice γ-Fe2O3@SiO2 permettant de fonctionnaliser leur surface par les peptides cationiques en utilisant la chimie click. Dans un premier temps, la synthèse et caractérisation des peptides et des nanoparticules cœur-coquilles ont été réalisées, puis la fonctionnalisation de ces nanoparticules par les peptides. L’internalisation des nanoparticules dans les cellules a ensuite été étudiée, par microscopie confocale combinée à des expériences de fuite de calcéine, et par microscopie électronique à transmission. Il a ainsi pu être montré que le greffage sur les nanoparticules de peptides riches en histidine permet de favoriser leur accès au cytosol.Magnetic nanoparticles (MNPs) are a promising class of functional nanomaterials in the biomedical field for various applications such as magnetic manipulation and magnetic hyperthermia. However, a major limitation of these approaches is their endosomal entrapment after internalization by the endocytosis pathway, where the ease of magnetic manipulation is restricted. The objective of this project was to improve the access of MNPs to the cytosol by functionalizing them with cationic peptides. Arg9 is a classical cell-penetrating peptide (CPP), able to enter cells by direct translocation, a transient perturbation of the plasma membrane which allows CPPs to reach the cytosol. On the other hand, it has been demonstrated that sequences rich in histidine residues promote endosomal escape, probably by proton sponge effect. MNPs used are iron oxide nanoparticles coated with silica γ-Fe2O3@ SiO2 allowing their surface to be functionalized by cationic peptides using click chemistry. First, the synthesis and characterization of peptides and core-shell nanoparticles was carried out, then the functionalization of these nanoparticles by peptides. The internalization of the nanoparticles in cells was then studied, using confocal fluorescence microscopy combined with calcein leakage experiments, and transmission electron microscopy. It was shown that the grafting onto nanoparticles of peptides rich in histidine promotes their access to the cytosol
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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