1,720,960 research outputs found
Localization and expression of two human b-defensins (HBD-1 and HBD-2) in intestinal biopsies of celiac patients
No full textPrimate beta-defensins--structure, function and evolution.
No full textHost defense peptides (HDPs) are endogenous antibiotics that play a multifunctional role in the innate immunity of mammals. Among these, β-defensins contribute to mucosal and epithelial defense, also acting as signal molecules for cellular components of innate and adaptive immunity. Numerous members of this family have been identified in mammalian and avian species, and genomic studies in human and mouse indicate a considerable complexity in their gene organization. Recent reports on the evolution of primate and rodent members of this family indicate quite a complex pattern of variation. In this review we briefly discuss the evolution of mammalian β-defensins in relation to other types of defensins, and then concentrate on the evolution of β-defensins 1 to 4 in primates. In particular, the surprisingly varied patterns of evolution, which range from neutral or weakly purifying, to positive selection to a high level of conservation are analyzed in terms of possible genetics, structural or functional implications, as well as to observed variations on the antimicrobial activity in vitro. The role of polymorphisms in the genes encoding for these host defense peptides in determining susceptibility to human diseases are also briefly considered. © 2005 Bentham Science Publishers Ltd
Effects of positively selected sequence variations in human and Macaca fascicularis beta-defensins 2 on antimicrobial activity.
No full textThe evolution of orthologous genes coding for -defensin 2 (BD2) in primates has been subject to positive
selection during the divergence of the platyrrhines from the catarrhines and of the Cercopithecidae from the
Hylobatidae, great apes, and humans. Three peptides have been selected for a functional analysis of the effects
of sequence variations on the direct antimicrobial activity: human BD2 (hBD2), Macaca fascicularis BD2
(mfaBD2), and a variant of the human peptide lacking Asp4, (D)hBD2, which is characteristic only of the
human/great ape peptides. hBD2 and mfaBD2 showed a significant difference in specificity, the former being
more active towards Escherichia coli and the later towards Staphylococcus aureus and Candida albicans. Asp4 in
the human peptide appears to be important, as (D)hBD2 was less structured and had a markedly lower
antimicrobial activity. The evolution of -defensin 2 in primates may thus have been driven, at least in part,
by different environmental pressures so as to modulate antimicrobial activity
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
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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