1,721,014 research outputs found
Cell reprogramming: expectations and challenges for chemistry in stem cell biology and regenerative medicine
No full textStudies on brain cytosol neuraminidase. II. Extractability, solubility and intraneuronal distribution of the enzyme in pig brain.
No full textRecent development in mammalian sialidase molecular biology
No full textThis review summarizes the recent research development on mammalian sialidase molecular cloning. Sialic acid–containing compounds are involved in several physiological processes, and sialidases, as glycohydrolytic enzymes that remove sialic acid residues, play a pivotal role as well. Sialidases hydrolyze the nonreducing, terminal sialic acid linkage in various natural substrates, such as glycoproteins, glycolipids, gangliosides, and polysaccharides. Mammalian sialidases are present in several tissues/organs and cells with a typical subcellular distribution: they are the lysosomal, the cytosolic, and the plasma membrane–associated sialidases. Starting in 1993, 12 different mammalian sialidases have been cloned and sequenced. A comparison of their amino acid sequences revealed the presence of highly conserved regions. These conserved regions are shared with viral and microbial sialidases that have been characterized at threedimensional
structural level, allowing us to perform the molecular modeling of the mammalian proteins and suggesting a monophyletic origin of the sialidase enzymes. Overall, the availability of the cDNA species encoding mammalian sialidases is an important step leading toward a comprehensive picture of the relationships between the structure and biological function of these enzymes
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
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
Sialidases in vertebrates: a family of enzymes tailored for several cell functions
No full textThis review summarizes the recent research development on vertebrate sialidase biology. Sialic acid-containing compounds play important roles in many physiological processes, including cell proliferation, apoptosis and differentiation, control of cell adhesion, immune surveillance, and clearance of plasma proteins. In this context, sialidases, the glycohydrolases that remove the terminal sialic acid at the non-reducing end of various glycoconjugates, perform an equally pivotal function. Sialidases in higher organisms are differentially expressed in cells and tissues/organs, with particular subcellular distribution and substrate specificity: they are the lysosomal (NEU1), the cytosolic (NEU2), and plasma membrane- and intracellular-associated sialidases (NEU3 and NEU4). The molecular cloning of several mammalian sialidases since 1993 has boosted research in this field. Here we summarize the results obtained since 2002, when the last general review on the molecular biology of mammalian sialidases was written. In those few years many original papers dealing with different aspects of sialidase biology have been published, highlighting the increasing relevance of these enzymes in glycobiology. Attention has also been paid to the trans-sialidases, which transfer sialic acid residues from a donor sialoconjugate to an acceptor asialo substrate. These enzymes are abundantly distributed in trypanosomes and employed to express pathogenicity, also in humans. There are structural similarities and strategic differences at the level of the active site between the mammalian sialidases and trans-sialidases. A better knowledge of these properties may permit the design of better anti-pathogen drugs
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
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