1,720,973 research outputs found
Potential amphiphilic antibacterial compounds
Full text linkPerseguendo la ricerca di una nuova classe di peptidi antimicrobici strutturalmente semplici, abbiamo ottimizzato una sintesi breve, economica e ad alto rendimento di derivati dell'acido α-idrazido anfifilico monocarico, con azione membranolitica. Tali composti, hanno esibito un'attività in vitro ad ampio spettro contro una varietà di batteri Gram-positivi e Gram-negativi, tra cui due ceppi multi-farmaco resistenti. Inoltre, hanno mostrato effetti sinergici con la tetraciclina nei confronti dei batteri sensibili, mentre sono stati osservati effetti sinergici o indifferenza per combinazioni con diversi antibiotici di prima linea verso ceppi multiresistenti. Nonostante la minima carica cationica, i migliori composti hanno dimostrato di essere selettivi verso le membrane cellulari batteriche rispetto alle membrane cellulari dei mammiferi. È stata anche dimostrata l'importanza di un'anfifilicità senza interruzioni.
Con l'obiettivo di somministrare dosi più basse di colistina riducendo gli effetti collaterali tossici, il Dipartimento di biologia chimica dell'HZI (Braunschweig, Germania) ha sviluppato un nuovo costrutto peptide-colistina. Consiste in una miscela di cinque regioisomeri in cui ciascuno dei gruppi amminici liberi della colistina è legato al terminale C con un peptide sintetico. La scissione del gruppo ammide introdotto da parte dei neutrofili dell'elastasi umana, rilascia la colistina direttamente sulla superficie dei batteri per ucciderli. Pertanto, sfruttando la metodologia della fase solida, abbiamo preparato in modo regioselettivo gli isomeri del costrutto della colistina al fine di indagare se tutti i regioisomeri subiscono la scissione selettiva da parte dell’ elastasi con la stessa efficacia e fedeltà. Quindi, abbiamo eseguito i test antimicrobici contro un ceppo di E. coli K12 e i risultati sono stati confrontati con l'attività della miscela regioisomerica.Pursuing the search for a new class of structurally simple mimics of antimicrobial peptides, we have optimized a short, cheap and high-yielding synthesis of mono-charged amphiphilic α-hydrazido acid derivatives, having a membranolytic action. They exhibited a broad-spectrum in vitro activity against a variety of Gram-positive and Gram-negative bacteria, including two multidrug-resistant strains. In addition, they showed synergistic effects with tetracycline toward sensitive bacteria, whereas either synergistic effects or indifference were observed for combinations with different first-line antibiotics toward multidrug-resistant strains. Despite the minimal cationic charge, the best compounds demonstrated to be selective toward bacterial cell membranes over mammalian cell membranes. The importance of a non-disrupted amphiphilicity was also demonstrated.
With the aim to administer lower doses of colistin reducing the toxic side effects, the Department of Chemical Biology at HZI (Braunschweig, Germany) developed a novel peptide-colistin construct. It consists of a mixture of five regioisomers where each of its free amino groups of colistin was coupled to the C-terminal of a synthetic peptide. The cleavage of the newly introduced amide group by human elastase neutrophils, releases colistin directly on the surface of bacteria in order to kill them. Thus, exploiting solid phase methodology, we regioselectively prepared the isomers of the colistin construct in order to investigate if all the regioisomers undergo selective cleavage by elastase with the same efficacy and fidelity. Then, we carried out the antimicrobial assays against a strain of E. coli K12, and the results were compared with the activity of regioisomeric mixture
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Giant cardiac lesion in anaplastic thyroid cancer
Full text linkCardiac metastases of ATC arerare. Benefits of cardiac surgery on early postoperative survival are very limited
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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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