1,720,963 research outputs found
Interleukin-13 and -4 expression in the central airways of smokers with chronic bronchitis
No full textThe aim of this study was to determine whether the T-helper 2-type cytokines interleukin (IL)-13 and -4 are involved in mucus hypersecretion, the hallmark of chronic bronchitis (CB). Surgical specimens were examined from 33 subjects undergoing lung resection for localised peripheral malignant pulmonary lesions: 21 smokers with symptoms of CB, 10 asymptomatic smokers (AS) and two nonsmokers with normal lung function. The number of IL-4 and -13 positive (+) cells in the central airways was quantified. To better assess the cytokine profile, a count was also made of IL-5+ and interferon (IFN)-gamma+ cells. Compared to AS, the CB group had an increased number of IL-13+ and -4+ cells in the bronchial submucosa, while the number of IL-5+ and IFN-gamma+ cells were similar in all the groups. No significant associations were found between the number of cells expressing IL-13 or -4 and the number of inflammatory cells. Double labelling showed that 13.2 and 12.9% of IL-13+ cells were also CD8+ and CD4+, whereas 7.5 and 5% of IL-4+ cells were CD8+ and CD4+, respectively. In conclusion, T-helper-2 and -1 protein expression is present in the central airways of smokers and interleukin-4 and -13 could contribute to mucus hypersecretion in chronic bronchitis
Cellular and structural bases of chronic obstructive pulmonary disease
No full textChronic obstructive pulmonary disease (COPD) is defined as a disease state characterized by poorly reversible airflow limitation that is usually both progressive and associated with an abnormal inflammatory response of the lung. Cigarette smoking is the most important risk factor for the development of COPD. However, only a minority of smokers develop COPD and the reason is still unknown. The pathological hallmarks of COPD are inflammation of the peripheral airways and destruction of lung parenchyma or emphysema. The functional consequence of these abnormalities is expiratory airflow limitation. Since the major determinants of expiratory flow are a driving pressure that promotes flow (elastic recoil of the lung) and an opposing resistance that inhibits flow (airway obstruction), the reduction in flow occurring in COPD is more correctly defined as airflow limitation rather than airflow obstruction, since both loss of elastic recoil and increase in airway resistance play an important role in the observed decrease in flow. Emphysema will contribute to the airflow limitation by reducing the elastic recoil of the lung through parenchymal destruction, as well as by reducing the elastic load applied to the airways through destruction of alveolar attachments. On the other hand, inflammation of the peripheral airways will contribute to the airflow limitation by increasing the thickness of the airway wall which, together with fibrosis and smooth muscle hypertrophy, may cause airway narrowing. The role of mucus hypersecretion in the development of chronic airflow limitation is still controversial. The main site of mucus hypersecretion, expressed clinically as chronic bronchitis, is the central airways, and there is increasing evidence that the central airways are inflamed in patients with COPD. Pulmonary hypertension is a common feature in patients with advanced COPD, but the precise mechanisms of increased vascular resistance are unclear. For many years, it has been regarded as a consequence of the hypoxic vasoconstriction that may occur in advanced stages of the disease. However, the lack of reversibility of pulmonary hypertension after hypoxemia correction suggests that it might be due at least in part to the development of pulmonary vascular inflammation and remodeling. In summary, in subjects with COPD, pathological changes can be found in the central airways, the peripheral airways, the lung parenchyma, and pulmonary arteries. Interestingly, some of these changes can already be present in the lungs of "normal" smokers, i.e. smokers with normal lung function, indicating that smoking itself is able to damage the lung even before airflow limitation occurs. In the present article we will focus on the cellular and structural changes present in the lungs of "normal" smokers and on those present in the lungs of smokers with COPD, in an attempt to underline the possible mechanisms contributing to airflow limitation in these patients. We will then review the few studies that described the cellular and structural changes that occur in severe COPD and those that occur during an exacerbation of the disease. Finally, we will address the effect of smoking cessation or antiiflammatory treatment in an attempt to investigate the potential reversibility of the pathologic lesions characteristic of COPD. In advanced COPD, changes in the right heart, the respiratory muscles, and the skeletal non-respiratory muscles as well as cachexia may also occur, but these systemic changes will not be discussed in this article
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
Airflow limitation in chronic bronchitis is associated with T-lymphocyte and macrophage infiltration of the bronchial mucosa
No full textTo investigate whether the airway inflammatory process is different in patients with chronic bronchitis with airflow limitation and those with chronic bronchitis without airflow limitation, we obtained bronchial biopsies from 14 subjects with chronic sputum production and fixed airway obstruction, and from 10 subjects with chronic sputum production and normal FEV1, all with a history of cigarette smoking. Paraffin-embedded and frozen bronchial biopsies were examined by immunohistochemistry to identify the number of neutrophils (neutrophil-elastase), eosinophils (antieosinophil cationic protein [EG-2]), mast cells (tryptase), T-lymphocytes (CD3), T-lymphocyte subpopulations (CD4 and CD8), B-lymphocytes, and macrophages (CD68) in the submucosa. Subjects with chronic bronchitis with airflow limitation had a greater number of T-lymphocytes (p < 0.01) and macrophages (p < 0.05) than subjects with chronic bronchitis without airflow limitation, whereas the T-lymphocyte subpopulations and the numbers of B-lymphocytes, neutrophils, eosinophils, and mast cells were similar in the two groups. When all the subjects were considered together, the number of T-lymphocytes correlated inversely with the values of FEV1 (r = 0.46, p < 0.02). In conclusion, airflow limitation in subjects with chronic bronchitis is associated with an increased number of T-lymphocytes and macrophages in the bronchial mucosa
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
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