1,721,223 research outputs found
Effects of hypotaurine on carbonate radical anion and nitrogen dioxide radical generated by peroxidase activity of Cu,Zn-superoxide dismutase
No full textCysteine sulfinate (CSA) and hypotaurine are recognized as key intermediates in the metabolic pathway leading from cysteine to taurine. The oxidation of sulfinic group to the respective sulfonate is a crucial point for generation of taurine in mammalian tissues. The mechanism of sulfinic group oxidation could not be related to specific enzymatic activities. However, oxidizing agents, such as hydroxyl radical, photochemically generated singlet oxygen and peroxynitrite have been reported to accomplish such oxidation in good yield.
Carbonate radical anion (CO3 radical) is receiving increasing attention as important mediator of biological processes and is a potent one-electron oxidant that is able to oxidize a variety of biotargets. Nitrogen dioxide radical (NO2) is well known as a reactive species capable to initiate both oxidation and nitration reactions. The pathogenic role of radical NO2 has been related mostly to the increased level of nitrated proteins detected under many disease
Regulation of polymorphonuclear leukocyte function by nitroenkephalin, a nitrated biomolecule formed by activated human neutrophils.
No full textThe protective effect of hypotaurine and cysteine sulphinic acid on peroxynitrite-mediated oxidative reactions
No full textThe protective activity of hypotaurine (HTAU) and cysteine sulphinic acid (CSA) on peroxynitrite-mediated oxidative damage has been assessed by monitoring different target molecules, i.e. tyrosine, dihydrorhodamine-123 (DHR) and glutathione (GSH). The inhibition of tyrosine oxidation exerted by HTAU and CSA both in the presence and the absence of bicarbonate can be ascribed to their ability to scavenge hydroxyl ((OH)-O-center dot) and carbonate (CO3 center dot-) radicals. HTAU and CSA also reduce tyrosyl radicals, suggesting that this repair function of sulphinates might operate as an additional inhibiting mechanism of tyrosine oxidation. In the peroxynitrite-dependent oxidation of DHR, the inhibitory effect of HTAU was lower than that of CSA. Moreover, while HTAU and CSA competitively inhibited the direct oxidation of GSH by peroxynitrite, HTAU was again poorly effective against the oxidation of GSH mediated by peroxynitrite-derived radicals. The possible involvement of secondary reactions, which could explain the difference in antioxidant activity of HTAU and CSA, is discussed
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
Aminoethylcysteine ketimine decarboxylated dimer protects submitochondrial particles from lipid peroxidation at concentration not inhibitory of electron transport.
No full textIn contrast with other inhibitors of the NADH dehydrogenase of the respiratory chain, the decarboxylated dimer of aminoethylcysteine ketimine protects bovine heart submitochondrial particles (SMP) from the NADH-Fe(+3)-ADP-induced lipid peroxidation. This effect, measured as inhibition of malondialdehyde formation, is concentration-dependent in the range 0.02-0.2 mM. This range of concentration is not inhibitory on NADH-oxidase activity of SMP. Furthermore the dimer is able to counteract the malondialdehyde formation stimulated by the Complex I inhibitors rotenone and N-methyl-4-phenylpyridinium (MPP+)
High perfomance liquid chromatography of the ketimine forms of aminoethylcysteine, lanthionine and cystathionine after precolumn derivatization with 2,4-dinitrophenylhydrazine.
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