1,720,958 research outputs found
Inhibition of calcium oxalate precipitation by bile salts
No full textBACKGROUND: Both urinary and biliary stones can contain calcium. Bile salts (BA), which are known to bind Ca2+, are commonly used to dissolve the latter but not the former. METHODS: The effect of physiologic BA on calcium oxalate (CaOx) precipitation was evaluated by a recently developed method. RESULTS: The Ca2+ binding properties of BA were confirmed by small but significant decreases in pH observed following addition of CaCl2 to bile acids solutions. More importantly, BA inhibited CaOx precipitation with effective concentrations of approximately 10-3 mol/L. The clinical relevance of the latter observation is presently unknown but it is of note that in the same in vitro assay, the activity of BA appeared comparable to that of citric acid, the most common drug for urolithiasis. Although BA do not reach mmol/L levels in urine, they are known to change the physicochemical properties of this fluid, possibly slowing down the crystal growth process. However, the hypothetical therapeutic use of BA in former stone patients would present at least two major problems: (i) hepatotoxicity and (ii) lithogenic activity, due to hyperoxaluria subsequent to increased intestinal absorption of oxalate. CONCLUSION: The ability of BA in effectively binding calcium ions and in inhibiting the precipitation of CaOx appears of interest from both a physiopathologic and a pharmacologic point of view, even if it does not currently seem exploitable for prophylactic or therapeutic purposes
Inhibition of Candida rugosa lipase by berberine and structurally related alkaloids, evaluated by high-performance liquid chromatography
No full textIt is known that certain microorganisms produce extracellular lipase to better colonize the skin and mucosal surfaces. Since different extracts from medicinal plants have anti-lipase activity (Shimura et al., Biosci. Biotechnol. Biochem., 56: 1478-1479, 1992), we examined the effects of selected natural substances on Candida rugosa lipase. In the presence of the compounds under examination, the enzyme was incubated with beta-naphthyl laurate, and beta-naphthol, produced by the enzymatic reaction, was extracted with ethyl acetate and analyzed by reversed phase HPLC, using a C-18 column. Thus, the inhibitory activity was calculated by a proper formula based on the variations of the area under the chromatographic peak of beta-naphthol. The method was validated by analyzing substances with known anti-lipase activity such as saturated fatty acids (C10-16) and tetracycline. Berberine and a number of structurally related alkaloids such as chelidonine, chelerythrine, and sanguinarine appeared active. This property of berberine and sanguinarine is of interest because they are used in pathological conditions in which microbial lipases could play a pathogenic role
Inhibition of protein denaturation by fatty acids, bile salts and other natural substances: A new hypothesis for the mechanism of action of fish oil in rheumatic diseases
No full textNatural hydrophobic substances like bile salts (cholate, deoxycholate, chenodeoxycholate, lithocholate and their conjugates with glycine and taurine), fatty acids (caprylic, capric, lauric, myristic, palmitic, stearic, oleic, linoleic, arachidonic, eicosapentaenoic and docosahexaenoic acid) were much more active (EC(50)congruent to 10(-4)-10(-5) M) than selected amino acids (EC50 > 10(-2) M) and inorganic salts (EC(50)congruent to 10(-1) M) in inhibiting heat-induced denaturation of human serum albumin in vitro. Fish oil, rich in n-3-polyunsaturated acids such as eicosapentaenoic acid and docosahexaenoic acid, administered p.o. (1 ml/kg) in the rat, protected ex vivo (after 2 hr) serum against heat-induced denaturation more than bendazac, a known antidenaturant drug. Thus, we speculated that the antidenaturant activity of fish oil may be partly tin addition to the known effect on endogenous eicosanoid composition) responsible for its beneficial effects in rheumatoid arthritis and other rheumatic conditions. In this connection, it is of note that the in vitro antidenaturant activity of fish oil fatty acids was higher than that of known antidenaturant drugs such as bendazac and bindarit and nonsteroidal anti-inflammatory drugs like phenylbutazone and indomethacin which could exert beneficial effects in chronic inflammatory conditions by stabilizing endogenous proteins
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
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
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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