1,720,965 research outputs found
Leukotrienes in the sputum and urine of cystic fibrosis children
No full text1. Leukotrienes (LTs) are potent pro‐inflammatory mediators with actions relevant to the pathophysiology of cystic fibrosis (CF), including increased mucus production, bronchoconstriction, leucocyte chemotaxis, and increased vascular permeability. We have therefore investigated the potential role of LTs in children with CF. Leukotriene E4 levels were assessed in the urine of 30 normal (N) children (aged 1.3‐12.7 years) and 30 CF children (1.6‐14.3 years). Sputum from 13 of the CF children was analysed from LTB4, LTC4, LTD4, and LTE4. LTs were separated by reversed‐phase h.p.l.c. and quantitated by radioimmunoassay. 2. Urinary LTE4 levels were log normally distributed, with geometric mean values (95% confidence intervals) of N: 88.4 (71.3‐ 111) pmol mmol‐1 creatinine (n = 30), and CF: 112 (70.6‐177) pmol mmol‐ 1 creatinine (n = 30; P greater than 0.05). Of the CF subjects, 33% had urinary LTE4 levels above 200 pmol mmol‐1 creatinine, compared with 3.3% of the N children. 3. In sputum, mean (+/‐ s.e. mean) LT concentrations were (pmol g‐1), LTB4: 44.3 +/‐ 10.8, LTC4: 4.9 +/‐ 1.3, LTD4: 1.8 +/‐ 0.9, and LTE4: 67.7 +/‐ 18.9 (n = 13). 4. Urinary LTE4 levels correlated significantly with sputum LTE4 levels (r = 0.673, P = 0.012), and with sputum levels of total cysteinyl‐LTs (r = 0.660, P = 0.014). 5. In conclusion, total cysteinyl‐LT content in sputum is 10‐ fold higher than previously reported, consisting primarily (91%) of LTE4. The high levels of LTE4 and LTB4 in sputum suggest involvement of LTs in the pathophysiology of CF. Urinary LTE4 levels may prove useful as a marker for cysteinyl‐LT production in sputum. 1990 The British Pharmacological Society</p
Reduction in leukotriene B4 generation by bronchoalveolar lavage cells in asthma.
No full textBackground: leukotrienes are inflammatory mediators implicated in the pathogenesis of asthma. The capacity of inflammatory cells within the airways to generate leukotrienes may be altered in asthma. This hypothesis was tested using bronchoalveolar lavage (BAL) to sample cells within the airways from atopic asthmatic and normal subjects, and by measuring their capacity to generate leukotriene B4 (LTB4) and leukotriene C4 (LTC4) in response to A23187, a potent stimulus of leukotriene generation.Methods: bronchoalveolar lavage was performed in 12 mild asymptomatic atopic asthmatic patients and 12 normal subjects. Mixed BAL cell aliquots (approximately 80% alveolar macrophages) were incubated with 0-20 μM A23187 for 10 minutes and with 4 μM A23187 for 0-30 minutes, and leukotrienes were measured by radioimmunoassay and high performance liquid chromatography. Results: mixed BAL cells from asthmatic subjects generated less LTB4 than cells from normal subjects in dose response and time course experiments (area under the curve 81.5 (0.0-228.5) ng·min 10-6 cells in asthmatic subjects and 197.9 (13.9-935.6) ng·min 10-6 cells in normal subjects. There were no differences in LTC4 generation between BAL cells from asthmatic and normal subjects. Conclusions: generation of LTB4 by BAL cells from atopic asthmatic subjects in response to A23187 was reduced. As the alveolar macrophage is the major source of LTB4 in BAL cells, these results probably reflect reduced generation of LTB4 by alveolar macrophages from asthmatic patients. This may be a consequence of monocyte migration into the lung, or altered alveolar macrophage function in asthma, or both.</p
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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