1,720,980 research outputs found
Mutation of tyrosine 332 to phenylalanine converts Dopa decarboxylase into a decarboxylation-dependent oxidative deaminase
No full textA flexible loop (residues 328-339), presumably covering the active site upon substrate binding, has been revealed in 3,4-dihydroxyphenylalanine decarboxylase by means of kinetic and structural studies. The function of tyrosine 332 has been investigated by substituting it with phenylalanine. Y332F displays coenzyme content and spectroscopic features identical to those of the wild type. Unlike wild type, during reactions with L-aromatic amino acids under both aerobic and anaerobic conditions, Y332F does not catalyze the formation of aromatic amines. However, analysis of the products shows that in aerobiosis, L-aromatic amino acids are converted into the corresponding aromatic aldehydes, ammonia, and CO2 with concomitant O2 consumption. Therefore, substitution of Tyr-332 with phenylalanine results in the suppression of the original activity and in the generation of a decarboxylation-dependent oxidative deaminase activity. In anaerobiosis, Y332F catalyzes exclusively a decarboxylation-dependent transamination of L-aromatic amino acids. A role of Tyr-332 in the Cα protonation step that catalyzes the formation of physiological products has been proposed. Furthermore, Y332F catalyzes oxidative deamination of aromatic amines and half-transamination of D-aromatic amino acids with kcat values comparable with those of the wild type. However, for all the mutant-catalyzed reactions, an increase in Km values is observed, suggesting that Y → F replacement also affects substrate binding.A flexible loop (residues 328-339), presumably covering the active site upon substrate binding, has been revealed in 3,4-dihydroxyphenylalanine decarboxylase by means of kinetic and structural studies. The function of tyrosine 332 has been investigated by substituting it with phenylalanine. Y332F displays coenzyme content and spectroscopic features identical to those of the wild type. Unlike wild type, during reactions with L-aromatic amino acids under both aerobic and anaerobic conditions, Y332F does not catalyze the formation of aromatic amines. However, analysis of the products shows that in aerobiosis, L-aromatic amino acids are converted into the corresponding aromatic aldehydes, ammonia, and CO2 with concomitant O-2 consumption. Therefore, substitution of Tyr-332 with phenylalanine results in the suppression of the original activity and in the generation of a decarboxylation-dependent oxidative deaminase activity. In anaerobiosis, Y332F catalyzes exclusively a decarboxylation-dependent transamination of L-aromatic amino acids. A role of Tyr-332 in the Calpha protonation. step that catalyzes the formation of physiological products has been proposed. Furthermore, Y332F catalyzes oxidative deamination of aromatic amines and half-transamination of D-aromatic amino acids with k(cat) values comparable with those of the wild type. However, for all the mutant-catalyzed reactions, an increase in K-m values is observed, suggesting that Y --> F replacement also affects substrate binding
La sensibilità retinica nei diabetici valutata con perimetria automatica Octopus 2000.
No full textIn pazienti afetti da retinopatia diabetica a evidente componente ischemica all' esame fluoroangiografico gli AA studiano la sensibilità retinica periferica mediante esame campimetrico.Le alterazioni campimetriche settoriali sono rapportate alle alterazioni ischemiche presenti all'esame fluoroangiografico. La valutazione della sensibilità residua nelle aree ischemiche è un utile parametro nella valutazione del grado di aggressività settoriale nel corso di un trattamento panfotocoagulativo al fine di ridurre al minimo la ulteriore compromissione del campo visivo stesso
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
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
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