1,720,973 research outputs found
Failure of ursodeoxycholic acid to prevent a cholestatic episode in a patient with benign recurrent intrahepatic cholestasis: a study of bile acid metabolism
No full textUrsodeoxycholic acid was administered to a patient with benign recurrent intrahepatic cholestasis to prevent cholestatic episodes. A detailed study of bile acid metabolism in this patient was carried out in the anicteric and icteric phases before and after ursodeoxycholic acid (750 mg/day) administration. Urinary, biliary and serum bile acids were measured by gas chromatography-mass spectrometry and by high-performance liquid chromatography techniques. During the anicteric phase the daily urinary excretion and serum concentrations of bile acids were within normal ranges, indicating normal hepatic uptake and secretion of bile acids during the cholestasis-free period. Only slight qualitative differences from normal individuals were observed; the relative proportions of deoxycholic acid in the bile and serum were higher, and 12-oxo-lithocholic acid was the predominant urinary bile acid. During the icteric phase a marked increase in the urinary excretion of primary bile acids and C-1, C-2, C-4 and C-6 hydroxylated metabolites was found. Serum bile acid concentrations increased before the rise in bilirubin, suggesting an acute disturbance in bile acid transport at the onset of the cholestatic attack. After ursodeoxycholic acid administration in the anicteric phase, bile became enriched with the exogenous bile acid, but little qualitative change was found in the other metabolites present in the urine, serum or bile during the anicteric or icteric phases. Prolonged administration of ursodeoxycholic acid failed to prevent recurrence of a cholestatic episode, suggesting that in benign recurrent intrahepatic cholestasis, oral ursodeoxycholic acid may be of little benefit in the treatment or prevention of cholestasis despite marked enrichment of the bile acid pool with this hydrophilic bile acid
Changes in bile acid composition in patients with primary biliary cirrhosis induced by ursodeoxycholic acid administration
No full textWe describe a detailed study of the effects of ursodeoxycholic acid administration on bile acid composition of the serum and bile of patients with primary biliary cirrhosis. Gas chromatography-mass spectrometry was used to analyze bile acids from 10 patients with primary biliary cirrhosis before and during ursodeoxycholic acid administration (500 mg/day, corresponding to approximately 8 mg/kg body wt), after group separation of the unconjugated and conjugated fractions by lipophilic anion exchange chromatography. These studies were directed at assessing whether the beneficial role of ursodeoxycholic acid in primary biliary cirrhosis was the consequence of a shift in the hydrophobic/hydrophilic balance of the bile acid pool and whether the hypercholeresis might result from the cholehepatic circulation of unconjugated ursodeoxycholic acid in bile. In basal conditions, the unconjugated bile acids accounted for only 5.5% and 2.5%, respectively, of the total bile acids of serum and bile; cholic acid was the major component of the conjugated fraction of serum and bile (56.0% +/- 4.0%, mean +/- S.E.M.), and ursodeoxycholic acid was present in only trace amounts. The conjugated fraction contained many unusual bile acids (representing 16.5% +/- 1.3% of total) including C25 bile acids, iso-chenodeoxycholic acid and several oxo-bile acids. After ursodeoxycholic acid administration biochemical indices of liver function all improved, but the proportions of the unconjugated bile acids in serum and bile did not significantly change.(ABSTRACT TRUNCATED AT 250 WORDS
Tauroursodeoxycholic acid for treatment of primary biliary cirrhosis. A dose-response study
No full textTauroursodeoxycholic acid, a highly hydrophilic bile acid, may be of therapeutic value for chronic cholestatic liver diseases. We performed a dose-response study on 24 patients with primary biliary cirrhosis who were randomly assigned to receive 500, 1000, or 1500 mg daily of tauroursodeoxycholic acid for six months. Biliary enrichment with ursodeoxycholic acid ranged from 15% to 48% and was not related with the dose. Serum liver enzyme levels decreased significantly after the first month of treatment with all the three doses. No significant difference among the three doses was found, although further reduction over time occurred with 1000 and 1500 mg daily. Plasma total and HDL cholesterol significantly decreased in patients administered the two higher doses. Diarrhea was the only side effect. In conclusion, a dose of about 10 mg/kg body wt/day of tauroursodeoxycholic acid should be used for long-term studies in patients with primary biliary cirrhosis
Effects of ursodeoxycholic acid on serum liver enzymes and bile acid metabolism in chronic active hepatitis: a dose-response study
No full textThe effect of ursodeoxycholic acid administration on liver function tests and on bile acid metabolism was investigated in 18 patients with chronic active hepatitis. Three different doses of ursodeoxycholic acid--250 mg, 500 mg and 750 mg--were administered daily to each patient for consecutive 2-mo periods. The order of doses was randomly assigned according to a replicated Latin-square design. A significant decrease in serum transaminases and gamma-glutamyl transpeptidase occurred with the lowest dose of ursodeoxycholic acid, which corresponded to 4 mg/kg body wt/day, and no further significant decrease with the higher doses was seen. Biliary bile acid composition was determined by high-performance liquid chromatography and gas chromatography-mass spectrometry. At entry the relative proportions of major bile acids were similar to those observed in normal individuals. During treatment the mean percentage of ursodeoxycholic acid in bile (22% with the 250 mg dose, 32% with the 500 mg dose and 34% with the 750 mg dose) was lower than values previously reported for patients with gallstones and normal liver function. The major bile acids were cholic, chenodeoxycholic and deoxycholic acids. A number of unusual bile acids were identified by gas chromatography-mass spectrometry, but these accounted for only 3% to 5% of the total and did not change during ursodeoxycholic acid therapy. No correlation between the improvement in liver function tests and the percentage of ursodeoxycholic acid in bile existed. These data suggest that even a slight enrichment of bile with ursodeoxycholic acid, as is attained with 250 mg/day, is effective in improving biochemical markers of liver function in patients with chronic active hepatitis
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
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