1,721,120 research outputs found
Cigarette smoke and human pulmonary immune responses to mycobacteria
No full textRecent epidemiological evidence suggests that up to 15% of worldwide tuberculosis (TB) cases may be attributable to tobacco smoking. The aim of the studies reported here was to gain insights into the effects of exposure to cigarette smoke on human cells that form part of the innate immune system of host defence in the lung. The experiments on the pulmonary effects of cigarette smoke confirm that exposure has a significant effect upon innate host defences. Significant reductions in the production of key cytokines implicated in defences against mycobacteria were observed, not attributable to impairment of mycobacterial uptake by cigarette smoke extract exposure. Furthermore, control of intracellular mycobacterial growth was impaired by cigarette smoke extract exposure
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
Tuberculosis-associated obstructive pulmonary disease: a clinical, radiological and pathophysiological study of the contribution of previous pulmonary tuberculosis in a community-based study of chronic obstructive pulmonary disease
No full textIncludes bibliographical references.Epidemiological studies in populations with a high burden of pulmonary tuberculosis (PTB), including the Burden of Obstructive Lung Disease (BOLD) survey performed in Cape Town, South Africa in 2005, have suggested an association between PTB and the development of chronic airflow obstruction (CAO). The nature of this association and mechanisms responsible for CAO has not been previously studied, but likely includes: airway narrowing (from bronchiolitis, bronchiectasis or persistent low-grade inflammation associated with healed PTB); and reduced lung elastic recoil from coexistent emphysema. The present study investigated the structure and function of the lung in subjects with tuberculosis-associated obstructive pulmonary disease (TOPD) identified in BOLD 2005, and aspects of its natural history and response to treatment. It also examined the diagnostic performance of the standardised and internationally accepted BOLD method for estimating the prevalence of COPD in community-based surveys, with specific reference to misdiagnosis that might lead to overestimates of prevalence
Silicosis among Cape gemstone workers : tigers' eye pneumoconiosis
Full text linkSilicosis continues to be an important occupational disease in South Africa, particularly in small, poorly regulated industries. A case series is described of six workers who developed silicosis whilst involved in the processing of semi-precious gem stones. They had been employed as stone sculptors in lapidaries where they processed tigers' eye, rose quartz, amethyst, quartz crystal and a variety of other locally occurring semi-precious stones. In five of the cases exposure was in small and poorly regulated lapidaries without specific dust control measures. The sixth was detected during the course of a health and hygiene survey (including dust sampling) that I conducted in one of two lapidaries still operating in the Western Cape. These workers developed serious disease. Progressive massive fibrosis (PMF) was noted in 4 of the 6 cases, three of whom had progression of their disease after cessation of exposure. With the development of PMF the initial restrictive pulmonary function abnormalities were followed by steadily worsening airflow obstruction. Lung biopsies confirmed silicosis in one case and were suggestive in a further two. Tuberculosis was confirmed in two cases and suspected and treated in a third. Workmen's' Compensation was awarded in five cases. The survey confirmed that in semiprecious gem stone processing, the risk of silicosis appears to be confined to stone sculptors. Tried and proven techniques of general and local exhaust ventilation combined with water or oil to control dust at source were capable of effectively reducing dust emission to acceptable levels
Hut lung : a study of domestically acquired pneumoconiosis in rural women
Full text linkPneumoconiosis in rural Transkeian women termed "Transkei Silicosis" has been thought to be caused by silica inhaled while grinding maize by traditional methods (Palmer and Daynes, 1967). This study was undertaken to investigate the features and causes of hut lung. The range of clinical, radiologic, histologic, pulmonary physiologic and broncho-alveolar lavage features in patients meeting the following criteria was assessed: i) rural women practising traditional cooking methods ii) with a diffuse nodularity on chest x-ray iii) and lung biopsy evidence of pneumoconiosis iv) and without occupational exposure v) or evidence of active tuberculosis. Smoke and dust levels were measured in rural dwellings during cooking and maize grinding and ground maize and grinding rocks were analysed. 25 patients were studied. 17 were non-smokers, 5 were pipe smokers and 3 smoked 10 or less cigarettes per day. 7 had evidence of previous tuberculosis. The radiological findings ranged from a diffuse fine miliary pattern through coarse nodules with coalescence, to extensive fibrosis resembling PMF. The histologic features revealed simple "anthracosis" in 12, anthracosis with macules in 6 and mixed dust fibrosis in 7, of which 2 had silicotic nodules and 1 PMF. No such findings were observed in the control lung biopsy specimens obtained at post-mortem from city dwelling Xhosa females. Mild to moderate airflow limitation (defined as an FEV1/FVC ratio of < 65% and/or RV> 145% of predicted) was present in 73% while a reduced T'LCO (< 80% predicted) was found in 76% of the patients. Cell numbers and differential counts in BAL fluid were normal but> 80% of the macrophages were heavily laden with inorganic inclusions. The mean smoke level during indoor open fire cooking was 30mg/m³. Respirable dust and quartz concentrations ranging from 3,03 to 5, 82mg/m³ and 0,097 to 0,186mg/m³ respectively were found during hand grinding with sandstone (100% quartz), but were lower (ranging from 2,62 to 3,40mg/m³ and 0,024mg/m³ respectively) when non-quartz containing dolerite was used. Calculated cumulative equivalent time-weighted average respirable dust concentrations were shown to be similar to those found in an average South African gold mine while calculated equivalent respirable quartz concentrations were well below those found in the worst exposed gold miners and well within the recommended threshold limit values of the National Institute for Occupational Safety and Health (NIOSH) and the World Health Organisation (WHO). Respirable quartz exposure alone was not sufficient to explain the changes found. Respirable non-quartz containing nuisance dust and intense smoke exposure were shown to be significant. It was concluded that: i) hut lung can be defined as a domestic pneumoconiosis that occurs in rural women who practise primitive cooking methods ii) hut lung typically occurs in rural maize grinding Transkeian women but can occur in other rural women iii) there is a wide clinical, spectrum radiological and histologic iv) the pulmonary physiological changes are predominantly those of airflow limitation with some CO transfer factor reduction v) cigarette and pipe smoking do not contribute to the aetiology or pulmonary physiological abnormalities vi) the bronchoalveolar lavage features may help differentiate this condition from miliary tuberculosis vi) the aetiology of hut lung is multifactorial with exposure to respirable quartz and non-quartz containing dust together with smoke particles from biomass fuelled fires all playing a significant role while previous tuberculosis may be a contributing factor
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
Risk factors for prolonged ventilation in patients with chronic obstructive pulmonary disease presenting with acute respiratory failure
No full textIncludes abstract.Includes bibliographical references (leaves 35-37).Patients with COPD presenting to the Emergency Unit with acute hypercapnic respiratory failure often require invasive mechanical ventilation and subsequent admission to the intensive care unit (ICU). These patients are at an increased risk of prolonged and complicated ventilation and often experience weaning difficulties. In addition, the impact of a previous episode of pulmonary tuberculosis that might have resulted in structural lung disease on the duration of mechanical ventilation in such patients has not previously been evaluated. Methods: All patients with COPD admitted to the Respiratory ICU at Tygerberg academic hospital from the 01st January 2004 until 31st December 2007 requiring intubation and invasive mechanical ventilation for acute hypercapnic respiratory failure were included in the study
Risk factors for tuberculosis in a low-income urban area of Cape Town, South Africa, with particular reference to the role of cannabis smoking
Full text linkBackground: The association between Mycobacterium tuberculosis infection and tobacco smoking has recently been highlighted. The reason for this association remains unclear, but is postulated to result from the effects of smoking on pulmonary host defences. Cannabis impairs the immune function of alveolar macrophages and has been reported to increase susceptibility to respiratory infections. Aim: To examine risk factors for both Mycobacterium tuberculosis disease and infection, in particular the effects of cannabis smoking. Methods: A cross-sectional population survey of 3512 persons aged ≥15 years was performed in a predominantly low-income urban area of Cape Town, South Africa. Information on a history of tuberculosis and various risk factors including cannabis smoking was collected by means of an administered questionnaire. Ziehl-Neelson stained sputum smears were examined for acid fast bacilli and cultured on Lowenstein Jensen slants. Tuberculin skin testing (TST) was performed and an induration of ≥10mm read after 48-72 hours was considered positive. One joint year is defined as one joint per day for one year. Results: The prevalence of ever smoking cannabis was 11.3% (23% in men; 2.6% in women) and 6.4% were current smokers. A history of tuberculosis was reported by 9.7%; current disease confirmed in 1 %, and 76% had a positive TST. After adjusting for age, sex, tobacco smoking, income, education, occupational exposure, incarceration, alcohol use and body mass index, persons with a cumulative cannabis exposure of >70 joint years (approximately equivalent to 20 tobacco packyears) had an increased risk of past/current tuberculosis disease (OR 3.2; Cl:1.8 - 5.6). Cannabis joint years did not show an association with tuberculosis infection. Conclusions: This population study shows that cannabis smoking is positively associated with past/current tuberculosis disease, suggesting that cannabis may be a risk factor in the development of tuberculous disease
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
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