1,720,977 research outputs found
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
Interaction of capsulate Haemophilus influenzae with human airway mucosa in vitro
No full textTwo pairs of isogenic capsulate and noncapsulate and one pair of capsulate fimbriate and nonfimbriate strains of Haemophilus influenzae type b were studied in an organ culture of human respiratory mucosa. Over 24 h, the numbers of recovered bacteria increased from the original inoculum size of 10(5) to 10(8) CFU/ml. Transmission electron microscopy and scanning electron microscopy showed that noncapsulate organisms caused significant epithelial damage, whereas capsulate strains did not. Association of noncapsulate bacteria with damaged epithelial cells was observed by 14 h of incubation. In contrast, capsulate organisms were associated with a dense, thick, gel-like matrix which was observed above the epithelial surface. These capsulate organisms were not seen to associate with the epithelial surface (by transmission electron microscopy), though they were occasionally seen adhering to cells by scanning electron microscopy. Fimbriate capsulate H. influenzae showed increased adherence to buccal cells compared with nonfimbriate capsulate organisms. There was also association of fimbriate capsulate bacteria with damaged organ culture epithelium in one of four experiments. It is concluded that both capsule and fimbriae affect the interaction of H. influenzae with human airway mucosa in vitro by influencing adherence to and damage of the epithelium.</p
The concentrations of clarithromycin and its 14-hydroxy metabolite in sputum of patients with bronchiectasis following single dose oral administration
No full textClarithromycin and its metabolite, 14-hydroxy-clarithromycin are active against a wide range of respiratory pathogens. Antibiotics generally penetrate poorly into respiratory secretions which may therefore continue to harbour bacteria following bronchial infection. We have studied sputum and serum concentrations of clarithromycin and 14-hydroxy-clarithromycin in eight patients with idiopathic bronchiectasis without infective exacerbations (five male, three female; mean age 53.3 years). Oral single dose administration of 250 or 500 mg clarithromycin, separated by at least 6 days, was given to each patient. Serum and sputum samples were collected (the latter by physiotherapy at 0, 1, 2, 4, 8, 24 and 0, 4, 8 and 24 h respectively after administration of each dose. Serum sol phase was obtained by high speed centrifugation and concentrations of clarithromycin and 14-hydroxy-clarithromycin were determined by high performance liquid chromatography. Serum Cmax for clarithromycin and 14-hydroxy-clarithromycin were 1.20 mg/L (3 h) and 0.37 mg/L (3.1 h) for clarithromycin (250 mg)) and were 2.78 mg/L (2.5 h) and 0.68 mg/L (2.6 h) for clarithromycin (500 mg) respectively. Sputum Cmax for clarithromycin and 14-hydroxy-clarithromycin were 0.52 mg/L (5 h) and 0.30 mg/L (5.5 h) for clarithromycin (250 mg) and were 1.59 mg/L (5 h) and 0.47 mg/L (5.5 h) for clarithromycin (500 mg) respectively. The sputum/serum percentage ratios at Cmax (sputum) for clarithromycin and 14-hydroxy-clarithromycin were 74.3% and 113.9% (250 mg) and 94.7% and 99.9% (500 mg) respectively. We conclude that oral administration of clarithromycin to patients with bronchiectasis results in rapid penetration into respiratory mucus with persistent drug concentrations that exceed its MIC for many respiratory pathogens.</p
Effects of human neutrophil elastase and Pseudomonas aeruginosa proteinases on human respiratory epithelium
No full textIt has been suggested that proteinase enzymes could play an important role in the pathogenesis of chronic bronchial infections including bronchiectasis and cystic fibrosis (CF). Because Pseudomonas aeruginosa frequently colonizes the respiratory tract in bronchiectasis and CF, we examined the in vitro effects of human neutrophil elastase (HNE) and proteinase enzymes produced by P. aeruginosa (elastase: PE; alkaline proteinase: PAP) on the ciliary beat frequency (CBF) and ultrastructure of human nasal ciliated respiratory epithelium. HNE (500 micrograms/ml) progressively reduced CBF and caused marked epithelial disruption; lower concentrations (100 and 20 micrograms/ml) also caused epithelial disruption but without slowing CBF. The effects of HNE (500 micrograms/ml) were completely abolished by adding alpha 1-antitrypsin (5 mg/ml). There was no synergy between HNE and pyocyanin, a product of P. aeruginosa which slows CBF. PE in phosphate-buffered saline also caused epithelial disruption without slowing CBF; however, PE in medium containing divalent metal ions caused CBF slowing as well as epithelial disruption at 100 micrograms/ml. PAP (500 micrograms/ml) had almost no effect on ciliated epithelium. The effects of HNE and PE on nasal and bronchial epithelium obtained from the same patient were similar. Light and transmission electron microscopy revealed that HNE and PE were cytotoxic and caused detachment of epithelial cells from neighboring cells and the basement membrane. There was cytoplasmic blebbing of the cell surface and mitochondrial damage; however, no increase of abnormalities in the ultrastructure of cilia on living cells was seen. These results support the hypothesis that HNE and PE contribute to the delayed mucociliary clearance and epithelial damage that is observed in patients with chronic bronchial infection.</p
Interaction of fimbriated and nonfimbriated strains of unencapsulated Haemophilus influenzae with human respiratory tract mucus in vitro
No full textAdherence to mucus may influence bacterial colonization of the respiratory tract. Clinical isolates of nontypable Haemophilus influenzae (NTHi) from the respiratory tract are often fimbriated. We wondered whether fimbriated strains have a different adherence from related nonfimbriated strains. A microtitre plate assay has been developed to study adherence of nontypable H. influenzae to mucus. Wells were coated by incubation either with sol phase of sterile mucoid secretions or with purified preparations of mucins. Two laboratory pairs of fimbriated (F+) and nonfimbriated (F-) nontypable H. influenzae, and six fresh clinical isolates of fimbriated nontypable H. influenzae each with nonfimbriated partners derived by serial passage on agar, were cultured to mid-log phase, washed, and then added to the wells. They were then incubated at 37 degrees C for 30 min before washing to remove unbound bacteria. Adherent bacteria were desorbed by agitation with 0.5% Tween 80 and a viable count performed. The two fimbriated laboratory strains (n = 12 and n = 17), and 5 of the 6 fimbriated clinical isolates were more adherent to sol phase than their respective nonfimbriated partners. Two nonfimbriated clinical isolates were more adherent to plastic than their fimbriated partners. A fimbriated laboratory strain was more adherent than its nonfimbriated partner both to a purified preparation of high molecular mass mucin and to the glycopeptide fraction of the same. We conclude that fimbriated strains of nontypable H. influenzae have increased adherence to sol phase of mucus and purified human respiratory tract mucin. The interactions of fimbriae with mucus are likely to be complex, and may involve both nonspecific and specific interactions.</p
Ciliary beat frequency and structure of recipient and donor epithelia following lung transplantation
No full textTo investigate possible changes following lung transplantation, the structure and in vitro ciliary beat frequency (CBF) of airway epithelium from the cytology brushings of 9 heart-lung (HLT) and 5 single-lung (SLT) transplant recipients were examined. The CBF of brushings taken proximal and distal to the anastomosis was measured 2-10 months following transplant. There was no difference between the measured mean CBF at the two sites or between the two groups; HLT CBF: distal 11.0 +/- 0.5 Hz (standard error of mean), proximal 10.5 +/- 0.4 Hz, SLT CBF: distal 11.7 +/- 0.9 Hz, proximal 12.0 +/- 0.6 Hz. Mean CBF of bronchial brushings (except distal brushings from SLT patients) was significantly lower than that from controls: 13.6 +/- 0.3 Hz (n = 7) (p less than 0.05). Transmission electron microscopy of epithelial brushings from 4 patients (3 HLT, 1 SLT) revealed epithelial abnormalities both proximal and distal to the anastomosis, particularly ciliary depletion, mitochondrial abnormalities and death of cells. No significant ciliary ultrastructural abnormalities were seen in any tissue. We conclude that epithelial abnormalities were observed both proximal and distal to the anastomosis following lung transplantation. These may contribute to impairment of mucociliary clearance.</p
- …
