1,720,962 research outputs found
STRUCTURAL CHARACTERIZATION OF THE EARLY STAGES OF THE BETA 2 MICROGLOBULIN AMYLOIDOSIS
Full text linkABSTRACT.
Background.
β-2 microglobulin (β2m) is an amyloidogenic protein responsible for dialysis related amyloidosis in man, which result in the deposition of β2m amyloid fibrils at a skeletal level. β2m is a 99 residue protein formed by two β-sheets linked by a disulphide bond. In the early stages of fibril formation, β2m associate into dimers and higher order oligomers that are structurally poorly characterized due to their transient nature. Furthermore, the aggregation properties of β2m are affected by its fold-stability. In particular, the DE loop region, which connect the D- and the E- strands, has been reported to be crucial for the β2m fold-stability.
Results.
Four monomeric β2m cysteine mutants (S20C, E50C, W60C and S88C) were produced and their correspondent disulphide-linked homodimers were prepared (DIMC20, DIMC50, DIMC60 and DIMC88). The aggregation properties, the crystallogenesis and the oligomerisation state in solution were tested for each β2m homodimer. DIMC20, DIMC50 and DIMC88 form amyloid fibrils, crystals and display a varying mixtures of dimeric and tetrameric species in solution, while DIMC60 is not amyloidogenic and is purely dimeric in solution. DIMC20 and DIMC50 X-ray structures (2.45 Å and 2.7 Å resolution, respectively) shared a non-covalent D-D strand interface that mediate the formation of a tetrameric assembly in both DIMC20 and DIMC50. Moreover, DIMC20 and DIMC50 in solution can catalyse the w.t. β2m fibrils formation in the absence of fibril seeds at pH 7.4, strongly suggesting that the D-D strand interface is involved in the early stages of β2m amyloid aggregation.
In order to further characterize the role of the DE loop in β2m fold-stability, a K58P-W60G β2m mutant was produced and purified. The K58P-W60G β2m mutant showed improved thermal and chemical stability and a faster folding compared to the w.t. β2m. The crystal structure of the K58P-W60G β2m mutant (1.25 Å resolution) showed that the internal disulphide bond was severed as reported by Electrospray ionization-mass spectrometry spectra, which display that a fraction of the K58P-W60G β2m mutant has a reduced disulphide bond. These data suggest a stabilizing role of Pro58 and stress the importance of the DE loop on the biophysical properties of the β2m
Filetti di dentici, di letrinidi o di lutjanidi? Identificazione della specie ittica mediante Isoelectric Focusing
No full textComputer assisted evaluation of IEF patterns in electrophoretic gels : identification of Smoothhounds (Mustelus mustelus, Mustelus asterias) and comparison with lower value sharks
No full textIn this work, the most commercially important Selachian species, smooth-hound (Mustelus mustelus) and starry smoothhound (Mustelus asterias), have been identified by polyacrylamide isoelectric focusing (IEF-PAGE), along with several shark species of minor commercial value. In Italy, these two smoothhound species are commonly subjected to fraudulent substitution with lesser valued sharks. After the electrophoretic runs, the band patterns of the two Mustelus species were compared with those of dogfish (Scyliorhinus canicula), spurdog (Squalus acanthias), blue shark (Prionace glauca) and black-mouthed dogfish (Galeus melanostomus), both visually and with gel analysis software. The actual isoelectric points were then submitted to cluster analysis to differentiate the single species, despite the possible occurrence of electrophoretic variations or protein polymorphism. Every shark showed species-specific band patterns and could therefore be well differentiated, as confirmed by statistical analysis
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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