1,720,958 research outputs found
ADAPTIVE CYTOPROTECTION - AN ENDOSCOPIC STUDY IN MAN
No full textWe studied the protective effect of the mild irritant 20% ethanol against the damage caused by the strong irritant 40% ethanol to the duodenal mucosa of 10 healthy volunteers. At time 0, placebo (1% ethanol) or 20% ethanol (6 ml) was sprayed directly onto the duodenal wall through an endoscope. After 15 min 40% ethanol (50 ml) was given; damage was assessed by endoscopic examination 30 min after ethanol. The damage was scored arbitrarily: score 0, no damage; 1, duodenal hyperemia; 2, one hemorrhagic lesion; 3, two to five hemorrhagic lesions; 4, five hemorrhagic lesions. In separate experiments, the effect of acetylsalicylic acid (20 mg/kg iv) on adaptive cytoprotection was evaluated. It was found that 1) 20% ethanol does not damage the duodenal mucosa, whereas 40% ethanol does; 2) duodenal hyperemia and hemorrhagic lesions caused by 40% ethanol can be prevented by the previous administration of 20% ethanol; and 3) acetylsalicylic acid does not damage the duodenal mucosa but abolishes the protective effect of 20% ethanol. 'Adaptive cytoprotection' is a physiological phenomenon in humans too and further supports the probable defensive role of endogenous prostaglandins in the gastrointestinal tract
EFFECTS OF AUTONOMIC NERVOUS-SYSTEM ON GASTRIC DAMAGE BY ETHANOL IN THE RAT
No full textTo study whether or not the autonomic nervous system influences the defense mechanisms of the gastric mucosa, groups of Sprague-Dawley rats were given stimulants and inhibitors of the different components of the vagus and celiac nerves before administration of absolute or 70% w/v ethanol. The effects of vagotomy and sympathectomy on "adaptive cytoprotection" were studied, as were the effects of blocking the muscarinic receptors and stimulation of β-adrenergic receptors. We found that: (1) cholinomimetic agents and norepinephrine make the damage caused by 70% ethanol worse; (2) atropine is the only agent that fully protects against absolute ethanol; (3) vagotomy and sympathectomy abolish the effects of atropine and adaptive cytoprotection; and (4) β-adrenergic stimulation replaces conditions that allow adaptive cytoprotection and the protection by anticholinergics. These results suggest that two different reflexes are triggered by ethanol: when low concentrations are given, the β-adrenergic-mediated effect is prevalent, with protection of the mucosa; when high concentrations are given, the cholinergic- mediated effect is prevalent with damage of the mucosa
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
HEPARIN PREVENTS STASIS-INDUCED THROMBOSIS THROUGH PROTECTION OF THE VENOUS ENDOTHELIAL-CELLS - AN ELECTRON-MICROSCOPIC STUDY IN RABBITS
No full textThis study was performed to see whether or not protection of the endothelial cells contributes to the antithrombotic effects of heparin. New Zealand albino rabbits were subjected to jugular vein stasis by single caudal ligation for 2 h. Three treatments were given: saline (control group), heparin (0.2 mg/kg) 5 or 45 min before ligature of the vein. Groups of 6-8 animals were killed at 0, 5, 15, 30 and 120 min. The following parameters were determined: (1) involution and damage of the endothelial cells by scanning and transmission electron microscopy; (2) incidence and weight of thrombi in the lumens of the veins after 2 h stasis, and (3) effects of heparin on APTT and anti-Xa activity. In the control group, stasis caused a considerable involution of the endothelial cells in the first 30 min, followed by fibrin deposition and thrombus generation. Heparin strongly reduced the damage to the endothelial cells, with very evident protection of the cell membranes, and prevented thrombus generation: there were significant decreases in both incidence and weight of thrombi. These effects of heparin were evident both shortly after (maximal anticoagulant effect) and long after (no anticoagulant effect) pretreatment. We think that, under the experimental conditions we used, heparin prevented venous thrombosis at least partially by protection of the endothelial cells, through unknown mechanisms
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