1,721,061 research outputs found
Cross-Talk between Inducible Nitric Oxide Synthase and Cyclooxygenase in Helicobacter-pylori-induced gastritis
No full textObjectives: The present study examined the cross-talk between prostanoids and nitric oxide (NO) in human gastric biopsies during Helicobacter pylori infection. Subjects and Methods: A pool of 1 or 2 biopsies per patient (11 H. pylori positive and 9 H. pylori negative) were incubated in the medium with/without drugs, 1400W and NS-398, inhibitors of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2), respectively. Levels of NO and prostaglandin E 2 (PGE(2)), predominant products of activity of NOS and COX enzymes, were measured in the medium whereas the expressions of iNOS and COX protein, examined by Western blotting, were measured in the biopsies. Results: The 11 patients with H. pylori infection showed a marked expression of COX-2 and iNOS proteins and high levels of PGE(2) and NO, as a consequence of iNOS and COX-2 activation, while proteins were absent and the level of nitrite and PGE(2) was low in the 9 noninfected patients. The COX-2 inhibitor decreased both NO and PGE(2). The iNOS-specific inhibitor decreased NO but did not have any effect on the increase in gastric mucosal PGE(2). Both inhibitors had no effect on the protein level of these two enzymes. Conclusions: The data showed that COX-2 inhibitor might modulate the iNOS pathway, suggesting that COX-2 activity and/or its products may be related to the functional activation of iNOS but not to the expression of iNOS protein
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
Prevalence of tuberculosis Infection and Comparison of Multiple-puncture liquid Tubercolin test and Mantoux Test among drug users
No full textIn order to determine the prevalence of latent infection due to Mycobacterium tuberculosis in drug users and to provide centres for drug users with a practical tool for tuberculosis screening, 237 drug users were subjected to the Monotest and, for reference purposes, to the Mantoux test. The overall prevalence of subjects with a tuberculin skin reaction size > or = 5 mm in the Mantoux test was 25.7%; utilizing a cut-off of > or = 10 mm, the prevalence was 11.4%. Irrespective of cut-off, the Monotest showed a sensitivity of > 90% and a specificity of > 80%. At a prevalence of 25.7%, and with cut-offs of > or = 5 or > or = 10 mm, the positive predictive value was 83% or 62.2%, respectively. Irrespective of cut-off, the negative predictive value was > 97%. In conclusion, the Monotest proved satisfactory as a tool for epidemiological screening in a population with a high prevalence for latent tuberculosis, namely drug users
Reflux associated cough is usually not associated with reflux: role of reduced cough threshold
No full textIn a recent article Sifrim and coworkers addressed the issue of the importance of weakly acidic reflux (as measured by 24 hour ambulatory pressure and pH-impedance monitoring) in patients with chronic cough. The presence of asthma, postnasal drip, or the use of ACE inhibitors was ruled out, so that an association with gastro-oesophageal reflux was probable. They found that only 15% of cough bursts were preceded by reflux episodes, which in 4% of cases were weakly acidic and therefore not detectable by conventional automated analysis of oesophageal pH tracings. Though the temporal relationship between acid or weakly acidic reflux and cough was highly significant, it could not be demonstrated in most episodes. In this respect their findings are in agreement with a previous study by Laukka and coworkers, who also used manometry for a more accurate timing of cough. Taken together, the results of the two studies suggest that the pathogenetic mechanisms usually proposed as a link between reflux and cough (micro/macroaspiration of refluxate into airways and vagally mediated cough reflex) may be involved, at best, in a minority of cough episodes.
A different explanation has therefore to be formulated, not requiring a strict temporal relationship between reflux and cough. We suggest that such explanation is represented by a low cough threshold induced by repeated reflux. We have previously demonstrated that patients with reflux oesophagitis present a tussive response to minute amounts of inhaled capsaicin. In our series, the temporal relationship between irritant inhalation and cough bursts was so reproducible and immediate that a casual association with a single reflux is unlikely. Rather, our finding strongly suggests the presence of a reduction in cough threshold, related to cumulated effect of repeated oesophageal acid exposures. These lead to nociceptor sensitisation, which has been reported to be reversible by PPI treatment. Actually, in our series of oesophagitis patients, only five days of omeprazole treatment produced a striking improvement in tussive reactivity, so that a dose of capsaicin 15-fold higher was required to elicit cough . Once this acid-driven mechanism is activated, a variety of otherwise subliminal stimuli (smoke, pollution, etc) can cause cough. For this reason, the temporal association of reflux with cough does not appear a reliable criterium to diagnose reflux-associated cough, even using state of the art methodology. Future studies will clarify whether variations in cough threshold after PPI therapy has a role for identifying among patients with cough the ones in whom the symptom is due to reflux
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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