1,720,954 research outputs found
Endodontic infections: management of pathogenic biofilms
Get PDFEndodontic infections are biofilm-associated hence the challenge in eradication of such infections with a high risk of losing the infected tooth. The mainstay of root canal treatment involves mechanical debridement and use of
chemical irrigants. However, irrigants currently employed are known to have poor biocompatibility with host cells. In addition, these chemicals may present wider health and environmental risks. Biofilms’ high tolerance to these irrigants means that treatment failure is commonplace. Therefore, there is pressing need for identification of an improved irrigant. Phytic acid (IP6), a natural agent
that has been proposed as a potential endodontic irrigant due to its chelating activity. However, its antimicrobial and antibiofilm activity is poorly studied. Therefore, the overarching aim of this research was to investigate antimicrobial characteristics of IP6. This study focused on pathogenic microorganisms associated with endodontic infections and included assessment of organisms from root canals with necrotic dental pulp.
IP6 antimicrobial activity was assessed against planktonic cultures and in vitro generated biofilms of infection-associated pathogens. IP6 was antimicrobial
against planktonic cultures and biofilms at low concentrations and exhibited bactericidal activity against E. faecalis with a 30 s contact time. IP6 also had
antibiofilm effects on mature mono and dual species biofilms.
The microbiota of root canals in teeth with necrotic pulp and periapical disease from patients of the Gulf region had high bacterial diversity and contained several antibiotic resistance genes and virulence factors. The in vitro biofilm
models generated from these clinical samples on hydroxyapatite (HA) coupons were reproducible and polymicrobial. IP6 exhibited antibiofilm action against these developed biofilms. Importantly, IP6 resulted in substantial inhibition of dual-species (E. faecalis and C. albicans) biofilm formation when used as a pre-conditioning agent for HA coupons. The overall results of this PhD research highlight the antimicrobial properties of IP6 and its potential for exploitation in biofilm inhibition and management
Antimicrobial effect of phytic acid on Enterococcus faecalis
Get PDFObjective One of the properties of an ideal root canal irrigant is the ability to eradicate Enterococcus faecalis which is one of the most resistant microorganisms encountered in persistent peri-radicular lesions. The aim of this study was to test the in vitro antibacterial effectiveness of a naturally occurring agent called phytic acid (IP6) against E. faecalis and compare it to the antibacterial activities of clinically used irrigants: sodium hypochlorite (NaOCl), ethylenediaminetetraacetic (EDTA), phosphoric acid (PA) and chlorhexidine (CHX).
Design The antimicrobial activities of 5% IP6, 5% NaOCl, 18% EDTA, 37% PA and 2% CHX against E. faecalis were determined using disk diffusion test. Minimum inhibitory concentration (MIC) was calculated by broth macrodilution method. The minimal bactericidal concentration (MBC) was determined for the used agents by culturing the clear broth of MIC tests.
Results The results of agar diffusion test showed statistically signiï¬cant differences between the groups. PA showed a larger zone when compared to other tested materials (p< 0.05). There was no statistical significant difference between NaOCl, EDTA and CHX (p=0.098). IP6 showed the smallest zone of inhibition when compared to all groups (p< 0.05).The recorded MIC and MBC values for IP6 were 0.156% and 0.625%; respectively. The MIC and MBC values for PA were 0.578% and 4.6% and for NaOCl 0.093% and 0.375%, respectively. EDTA MIC value was 0.14 % but it showed no bactericidal activity. CHX was excluded from MIC test as immediate precipitation and turbidity occurred after mixing CHX with Mueller Hinton Broth.
Conclusions Within the limitation of this study and despite that IP6 showed the smallest zone of inhibition in agar diffusion test, the results of MIC and MBC indicated that IP6 exhibits in vitro antibacterial effect against E. faecalis at low concentrations
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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