1,720,965 research outputs found
Thyme essential oil and its phenolic derivatives are effective anticoccidial and antibacterial against Eimeria tenella and Clostridium perfringens in vitro
No full textCoccidiosis, caused by protozoan parasites of the genus Eimeria, is one of the main threats for aviculture, as it causes severe hemorrhagic diarrhea and acts as a predisposing factor for necrotic enteritis, whose causative agent is Clostridium perfringens. The aim of this study was to investigate in vitro the anticoccidial and anticlostridial efficacy of thyme essential oil and its main phenolic bioactive compounds (thymol, carvacrol and eugenol) against E. tenella and C. perfringens, respectively by invasion and minimal inhibitory concentration (MIC) assays, in comparison with conventional antibiotics.
For the invasion assay, confluent Madin-Darby bovine kidney cells were challenged with E. tenella sporozoites (5x104/cm2), without (control) or with various treatments: salinomycin (5 ppm), thyme oil (40 ppm, thymol content 50%), thymol, carvacrol or eugenol (20 ppm each). After 2 and 24 h at 37°C the efficiency of invasion was determined by counting free sporozoites left in the medium outside cells. For the MIC assay, a broth microdilution method on 96-well microtiter plates was used to test a range of concentrations (2-fold dilutions) of bacitracin (64-0.5 ppm), thyme essential oil (2000-62.5 ppm, thymol content 50%), thymol, carvacrol or eugenol (7.5-0.23 mM). Clostridium perfringens ATCC® 13124 strain (105 CFU/mL) was incubated with the substances under anaerobic conditions in Reinforced Clostridial Medium at 37°C for 24 h. After incubation, the absorbance at 630 nm was read with a spectrophotometer to measure bacterial growth. The MIC was defined as the lowest concentration that resulted in null absorbance. Data were analyzed with one-way ANOVA and differences considered significant at p<0.05.
The invasion assay showed that all the treatments significantly inhibited E. tenella invasion efficiency compared to the control already after 2 hours by 55% on average and similarly at 24 h with the highest reduction for salinomycin (-54% compared to control) and an average reduction of 35% for all the botanical treatments (p<0.001). Against C. perfringens the MIC values were found for bacitracin at 2 ppm, for thymol and carvacrol at 1.87 mM, for eugenol at 3.75 mM and for thyme oil at 500 ppm (equivalent to 1.66 mM of thymol).
In conclusion, both thyme essential oil and its main phenolic bioactive compounds demonstrated anticoccidial and bactericidal activity against E. tenella and C. perfringens in vitro. Thus, these botanicals could be valuable tools to counteract the causative agents of avian coccidiosis and necrotic enteritis
Antimicrobial kinetics of a blend of bioactive compounds and its role in maintaining epithelial integrity during a Clostridium perfringens challenge on a chicken intestinal cell line
No full textLe thymol, le carvacrol et l’eugénol réduisent la croissance d’Escherichia coli K88 et l’expression des gènes de virulence in vitro
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Organic Acids and Nature Identical Compounds as Potential Novel Strategies to Manage Post-Weaning Diarrhea
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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
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