1,720,987 research outputs found
EFFECT OF SUBINHIBITORY CONCENTRATIONS OF CIPROFLOXACIN AND FLEROXACIN ON THE OPSONIZATION AND PHAGOCYTOSIS OF BACTERIA
No full textEffect of sub-minimal inhibitory concentrations of ciprofloxacin and fleroxacin on the bacterial capsular antigen and opsonophagocytosis by human polymorphonuclear leukocytes.
No full textWe have studied the effect of sub-minimal inhibitory concentrations (sub-MIC) of ciprofloxacin and fleroxacin on capsulated (K+) and non-capsulated (K-) Gram-negative bacilli (Escherichia coli O1:K1, O7:K1, O1:K-, O7:K-, and Klebsiella oxytoca) as well as on Staphylococcus aureus and we investigated the interaction of antibiotic pretreated bacteria with human serum and polymorphonuclear leukocytes (PMN). Following overnight growth in the presence of 1/2 MIC of the antibiotics, bacteria were opsonized in human serum and incubated with PMN. Opsonophagocytosis was quantified as the ratio of uptake by PMN of radioactively labeled bacteria. Ciprofloxacin and fleroxacin enhanced the phagocytosis rate of E. coli K+ strains (control 5-10%; 1/2 MIC of ciprofloxacin and fleroxacin 70-80%) of K. oxytoca (control O-2%; 1/2 MIC of ciprofloxacin and fleroxacin 35-40%) as well as of Staph. aureus (control 5-10%; 1/2 MIC of the antibiotics 35-40%). Opsonophagocytosis of K- strains was not altered. The enhancement of opsonophagocytosis was a complement dependent process. Exposure of capsulated E. coli to ciprofloxacin as well as to fleroxacin resulted in decreased amounts of the capsular antigen
The influence of subminimal inhibitory concentrations of netilmicin and ceftriaxone on the interaction of Escherichia coli with host defences.
No full textThe effect of sub-MICs of netilmicin and ceftriaxone on the interaction between encapsulated and unencapsulated strains of Escherichia coli and certain host defence mechanisms, i.e. complement activation, opsonization, phagocytosis by human polymorphonuclear leucocytes (PMN), and serum bactericidal activity have been studied. Experiments were carried out testing antibiotics either alone or in combination. Non-capsulated strains of E. coli activated complement rapidly and were easily phagocytosed and killed after opsonization in human pooled serum. Pretreatment of these strains with sub-MICs of antibiotics did not change the rate of opsonization or the degree of uptake by PMN, but did enhance serum sensitivity. Capsulated strains of E. coli were both poorly opsonized and resistant to serum bactericidal activity. Treatment of these strains with sub-MICs of antibiotics enhanced complement consumption as well as phagocytosis by PMN, but did not affect serum-resistance
The influence of cefepime on opsonophagocytosis of bacteria.
No full textThe effect of subminimal inhibitory concentrations (sub-MICs) of a semi-synthetic beta-lactam antibiotic, cefepime (BMY 28142), was studied on the opsonophagocytosis by human polymorphonuclear leukocytes (PNMs) of strains of Escherichia coli, Klebsiella oxytoca and Staphylococcus aureus. Cefepime-treated Gram-negative bacteria were not better phagocytosed by PMNs; however the uptake of one of three S. aureus strains was enhanced. The effect of cefepime on the uptake of strains of E. coli was compared to that of two other beta-lactam antibiotics, mecillinam and ceftriaxone. Exposure of E. coli to sub-MICs of mecillinam and ceftriaxone enhanced phagocytosis by PMNs
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
- …
