1,720,957 research outputs found
Induction of staphylococcus aureus small colony variants by peritoneal dialysis solution and evaluation of antimicrobial susceptibility, biological growth and biofilm formation
No full textDie Peritoneal Dialyse assoziierte Peritonitis (PDAP) ist die häufigste Komplikation, die bei der Peritoneal Dialyse (PD) beobachtet wird. Die Keime, die am öftesten eine PDAP auslösen sind koagulase-negative Staphylokokken, gefolgt von Staphylokokkus aureus (S. aureus) und in bis zu 21% der Fälle, lassen sich keine auslösenden Keime im Dialysat auffinden. Weiters wurde beschrieben, dass eine hohe Anzahl der Kultur negativen PDAPs von gram positiven Kokken ausgelöst wurden. Auch bei „relapsing“ PDAPs wurden im Dialysat auffällig viele gram positive Erreger nachgewiesen.
Die Induktion von schwer kultivierbaren S. aureus small colony variants (SCVs) durch Peritonealdialyse-Lösung (PDL) könnte eine mögliche Erklärung für diese Kultur negativen PDAPs sein. Weiters könnte die hohe Anzahl an gram positiven Infektionen, die bei relapsing PDAPs gefunden wurden, auf die bekannte Persistenz von SCVs zurückzuführen sein.
Drei verschiedene S. aureus Stämme (ATCC 6538, 29213, 33592), wurden für mehrere Tage in einer kommerziell zur Verfügung stehenden PDL (Physioneal®) induziert, bis es zur Ausbildung des SCV Phänotyps kam. Anschließend wurden diese mit dem Wildtyp (WT) und mit SCVs, die mit Gentamicin induziert wurden, auf etwaige mikrobiologische Unterschiede untersucht. Dazu wurde die minimale Hemmkonzentration (MHK), Proliferationsrate und Biofilmbildung für WT, Gentamicin-SCVs sowie PDL-SCVs ermittelt und verglichen.
Zusammenfassend wurde gezeigt, dass es möglich ist mittels PDL unter Laborbedingungen SCVs herzustellen.
Die Untersuchung der antimikrobiellen Suszeptibilität durch Epsilometertest (E-Tests), wies starke Unterschiede zwischen WT und SCVs (sowohl Gentamicin-SCVs als auch PDL-SCVs) auf. Die Proliferationskurven veranschaulichten weitere Unterschiede zwischen SCVs und WT.
So kam es bei fast allen SCVs zu einer erhöhten Latenz-Phase und dadurch zu einer verzögerten exponentiellen Phase. Auch die Biofilmbildung war bei einigen PDL-SCVs und Gentamicin-SCVs signifikant (p<0.05) besser als bei deren jeweiligen WT.The most common form of complication, which can be observed when using peritoneal dialysis (PD) is peritoneal dialysis associated peritonitis (PDAP). The organisms most often responsible for causing PDAP are coagulase-negative Staphylococci, closely followed by Staphylococcus aureus (S. aureus). In up to 21% of cases no causative organism can be found in the PD effluent. Furthermore, it has been found that a high amount of culture negative PDAPs were triggered by gram-positive Cocci. This was also seen in the PD effluent of patients with relapsing PDAPs, where a noticeable number of gram-positive Pathogens could be attested.
A possible explanation for such culture negative PDAPs could be the induction of small colony variants (SCVs) by PD solution (PDS). Moreover, the high amount of gram-positive infections in relapsing PDAPs, could be attributed to the commonly known persistence of SCVs.
Three individual strains of S. aureus (ATCC 6538, 29213, 33592) were induced in a commercially obtainable PDS (Physioneal ®) for some days, until the SCV phenotype was achieved.
Subsequently said phenotype was compared to the wildtype (WT) and gentamicin induced SCVs (Gentamicin-SCVs) to probe for differentiating microbiological differences. For that purpose, the minimal inhibitory concentration (MIC), growth curves and biofilm formation for WT, Gentamicin-SCVs and PDS induced SCVs (PDS-SCVs) were determined and compared.
The process evidenced that it is possible to fabricate SCVs through PDS under laboratory conditions.
Strong distinctions between WT and SCVs (Gentamicin-SCVs as well as PDL-SCVs) could be found when examining the antimicrobial susceptibility by means of epsilometertest (E-test). The growth curves illustrated further differences between SCVs and WT. For example, almost all SCVs showing a heightened latency-phase and therefor a delayed exponential-phase. Another finding was that the formation of a biofilm was improved significantly in some PDS-SCVs and Gentamicin-SCVs (p<0.05) when compared to the respective WT.eingereicht von Gerhard MoosederAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersDiplomarbeit Medizinische Universität Wien 202
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
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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