1,721,020 research outputs found
Spontaneous Release of Human Serum Albumin S-Bound Homocysteine in a Thiol-Free Physiological Medium
No full textElevated plasma homocysteine (Hcy) concentrations independently predict cardiovascular disease. However, the transport of Hcy into pathological tissues such as atherosclerotic plaques, characterized by relatively low local thiol concentrations, is largely unknown. We sought to address if albumin-bound Hcy can be released in a thiol-free medium with or without previous incubation with Hcy and homocysteine thiolactone (HTL). We found that Hcy release was dependent on the baseline amount of albumin-bound Hcy. After 48 h incubation in a thiol- free medium the quantity of albumin-bound Hcy released from commercial human serum albumin (HSA) was 1.15 mmol/mol prot. If HSA was pre-incubated with 50 μmol/L reduced Hcy and then transferred into a free-thiol medium (HSA-S-Hcy), the amount of Hcy released after 48 h increased to 33.5 mmol/mol prot. If HSA was pre-incubated with 5 mmol/L HTL and then with 50 μmol/L of reduced Hcy (HSA-HTL-S-Hcy), the amount of Hcy released increased to 92.8 mmol/mol prot. Hcy release from HSA-HTL-S-Hcy further increased in presence of cysteine (Cys), glutathione (GSH), or Cys + GSH in the medium. Therefore, a significant amount of albumin-bound Hcy is released into thiol-free environments, similar to atherosclerotic plaques, with potential deleterious effects on vascular homeostasis, atherosclerosis and thrombosis
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
Determination of homocysteine thiolactone, reduced homocysteine, homocystine, homocysteine–cysteine mixed disulfide, cysteine and cystine in a reaction mixture by overimposed pressure/voltage capillary electrophoresis
No full textAn elevated level of thiol amino acid homocysteine is associated with several complex disorders. Homocysteine ability to bind proteins, thereby modulating their structure and function, is proposed to be one of the mechanisms of homocysteine induced pathogenecity. Homocysteine and homocysteine thiolactone bind to protein cysteine and lysine residues respectively. A major hurdle in studying protein homocysteinylation is the lack of suitable analytical techniques to determine simultaneously the concentrations of reduced and oxidized forms of homocysteine and cysteine (especially homocysteine–cysteine mixed disulfide) together with thiolactone formed during the reaction of homocysteine or thiolactone with proteins. Herein we report a capillary electrophoresis method to determine simultaneously the levels of these intermediates. For this 40 mmol/L Tris phosphate buffer at (pH 1.60) was used as running electrolyte, and the separation was performed by the simultaneous application of a CE voltage of 15 kV and an overimposed pressure of 0.1 psi. A rapid separation of these intermediates in less than 6 min with a good reproducibility of both peak areas (CV < 2%) and migration time (CV < 0.2%) was obtained. The applicability of our method was validated by incubating reduced homocysteine and albumin and measuring the reaction intermediates in the solution mixture
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
Hydrolysis of homocysteine thiolactone results in the formation of Protein‐Cys‐S‐S‐homocysteinylation
Full text linkAn increased level of homocysteine, a reactive thiol amino acid, is associated with several complex disorders and is an independent risk factor for cardiovascular disease. A majority (>80%) of circulating homocysteine is protein bound. Homocysteine exclusively binds to protein cysteine residues via thiol disulfide exchange reaction, the mechanism of which has been reported. In contrast, homocysteine thiolactone, the cyclic thioester of homocysteine, is believed to exclusively bind to the primary amine group of lysine residue leading to N-homocysteinylation of proteins and hence studies on binding of homocysteine thiolactone to proteins thus far have only focused on N-homocysteinylation. Although it is known that homocysteine thiolactone can hydrolyze to homocysteine at physiological pH, surprisingly the extent of S-homocysteinylation during the exposure of homocysteine thiolactone with proteins has never been looked into. In this study, we clearly show that the hydrolysis of homocysteine thiolactone is pH dependent, and at physiological pH, 1 mM homocysteine thiolactone is hydrolysed to ~0.71 mM homocysteine within 24 h. Using albumin, we also show that incubation of HTL with albumin leads to a greater proportion of S-homocysteinylation (0.41 mol/mol of albumin) than N-homocysteinylation (0.14 mol/mol of albumin). S-homocysteinylation at Cys34 of HSA on treatment with homocysteine thiolactone was confirmed using LC-MS. Further, contrary to earlier reports, our results indicate that there is no cross talk between the cysteine attached to Cys34 of albumin and homocysteine attached to lysine residues
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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