1,720,959 research outputs found
Helicobacter pylori CagA plus ve infection increases the oxidative DNA damage of gastric mucosa.
No full textIdentification of the phenotype of the gastric mucosa in patient's with Barrett's esophagus with and without H-pylori infection
No full textPatients younger than 40 years with gastric carcinoma - Helicobacter pylori genotype and associated gastritis phenotype
No full textBACKGROUND: In the general population, Helicobacter pylori (H. pylori), particularly the cagA positive strain, has been associated with intestinal-type gastric carcinoma. Gastric carcinomas are rarely observed in patients age < or = 40 years. Host-related factors have been thought to be more important than environmental agents in these early-onset cancers. The aim of this study was to ascertain the possible role of H. pylori infection and that of cagA positive strains in the development of gastric carcinoma in these young patients.
METHODS: In this case-control study, 105 gastric carcinoma patients (male-to-female ratio = 1.1; mean age, 34.4 years; range, 16-40 years) and an equal number of controls (matched for gender and age) were retrospectively selected from the same geographic area. The phenotypes of gastritis and H. pylori were histologically assessed, and the presence of the ureC gene, which is indicative of H. pylori infection, and the cagA genotype were determined by polymerase chain reaction. Gastric carcinoma risk was calculated by both univariate and multivariate statistical methods, taking into account the cancer phenotype, the gastritis phenotype detected in both patients and controls, and the H. pylori genotype.
RESULTS: For 74 diffuse and 31 intestinal gastric carcinomas, multivariate logistic regression analysis produced results consistent with those of univariate statistical tests, showing a significant association between gastric carcinoma and both H. pylori infection (odds ratio [OR] = 2.79; 95% confidence interval [CI] = 1.52-5.11) and cagA positive status (OR = 2.94; 95% CI = 1.56-5.52).
CONCLUSIONS: In young Italian patients with gastric carcinoma, the significant association with cagA positive H. pylori infection suggests that the bacterium has an etiologic role in both diffuse-type and intestinal-type gastric carcinom
Gastrin stimulates gastric mast cells in rabbits
No full textIn a previous study we demonstrated that in human gastric mucosa tryptase was localized only in mast cells and that its levels were correlated with serum gastrin, suggesting a link between gastrin action and mucosal mast cell function. The aim of the present study was to discover whether pentagastrin injection could stimulate gastric mucosal mast cells in rabbits. Ten female rabbits (group S) were injected s.c. with pentagastrin (10 mu g/kg); another group of ten animals (group C) was injected s.c. with an equal volume of saline solution. One hour after the injection the rabbits were sacrificed and their stomachs removed. Antrum (A), corpus (C) and fundus (F) mucosal homogenates were assayed for total protein, tryptase, pepsinogen A (PGA), histamine and gastrin. Histamine tissue levels were significantly lower in group S than in group C in the antrum (Mann-Whitney test: U = 82, P < 0.01) and in the corpus (U = 83, P < 0.005). Tryptase levels were significantly higher in group S than in group C in all gastric areas (antrum: U = 95, P < 0.001; corpus: U = 85, P < 0.005 and fundus: U = 75, P < 0.05). Total protein, PGA and gastrin did not vary significantly between groups. In group C, no significant correlations were found among the five parameters. In group S, corpus tryptase was correlated with fundus tryptase (Spearman's r = 0.831, P < 0.01). The same relationship was observed for histamine (r = 0.672, P < 0.05). In group S, antrum gastrin was inversely correlated with antrum tryptase (r = -0.903, P < 0.001), and with corpus PGA (r = -0.806, P < 0.05). This study demonstrates that bolus pentagastrin administration stimulates gastric mucosal mast cells in the rabbit
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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