1,720,971 research outputs found
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
Effects of CC14 poisoning on metabolism of dolichol in RAT liver microsomes and golgi apparatus
No full text: Carbon tetrachloride (CCl4) poisoning affects glycoprotein processing and maturation at the level of rat liver microsomes and Golgi apparatus. HPLC analysis showed that within 5-60 min after CCl4 administration the levels of total dolichol, free dolichol and dolichyl-phosphate strongly decreased both in total microsomes and in Golgi apparatus. The most marked and early reduction of total dolichol was observed in the secretory membranes of Golgi area already 15 min after CCl4 poisoning. The incubation of CCl4-pretreated isolated hepatocytes with [3H]-mevalonate showed a significant slowing down of the label incorporation into both free-dolichol and dolichyl-phosphate. Moreover, lipid peroxidation might cause alterations in the molecular structure of both free-dolichol and dolichyl-phosphate. A notable prevention of dolichol decrease was observed in animals pretreated with vitamin E. The results suggest that the prooxidant activity of CCl4 is able to affect the metabolism of dolichol either by increasing the oxidative degradation or impairing the biosynthetic pathway
Good glycaemic control reduces oxidation and glycation end-products in collagen of diabetic rats
No full textBlood glucose control plays a prominent role in the aetiology of diabetic complications. Recent data support the hypothesis that non-enzymatic pathways (glycation and oxidation) are involved in the pathogenesis of tissue damage in diabetes mellitus. In this study the level of pentosidine, a marker of glycation, and the intensity of collagen-linked fluorescence glycation (370/440 and 335/385 nm) and oxidation-related (356/460 and 390/460 nm), have been examined in spontaneously diabetic rats with good and poor glycaemic control. Pentosidine increased dramatically in rats with poor control, and slightly in those with good control. At the end of the study, after 6 months of diabetes, pentosidine levels were 13 ± 5 and 2.1 ± 0.5 pmol/mg collagen, respectively (control rats: 1.1 ± 0.1 pmol/mg collagen). A similar pattern was observed for both glycation or oxidation-related fluorescence. The group of rats with poor control always showed elevated average values when compared to rats with good control, with a relative increase of over 200%. The results emphasize the role of good glycaemic control in preventing the growth of glycation or oxidation end-products in collagen. On comparison between the general mean level of all glycated haemoglobin and the mean pentosidine level of the three groups, a very good exponential correlation was found (r = 0.993, p < 0.001). The fluorescence values presented a less strong relationship, but a correlation with glycaemic control was still present. If the post-translational modifications of proteins play a leading role in the pathogenesis of complications it is possible to conclude that strict glycaemic control, obtained by accurate insulin therapy can prevent them by inhibiting the non-enzymatic modification of proteins and delaying their accumulation in collagen. The therapeutic implications are obvious
RAGE Expression and ROS Generation in Neurons: Differentiation versus Damage
No full textRAGE is a multiligand receptor able to bind advanced glycation end-products (AGEs), amphoterin, calgranulins, and amyloid-beta peptides, identified in many tissues and cells, including neurons. RAGE stimulation induces the generation of reactive oxygen species (ROS) mainly through the activity of NADPH oxidases. In neuronal cells, RAGE-induced ROS generation is able to favor cell survival and differentiation or to induce death through the imbalance of redox state. The dual nature of RAGE signaling in neurons depends not only on the intensity of RAGE activation but also on the ability of RAGE-bearing cells to adapt to ROS generation. In this review we highlight these aspects of RAGE signaling regulation in neuronal cells
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
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