1,721,013 research outputs found
Bacterial predators and BALOs: Growth protocol and relation with mitochondria
No full textThe microbial world is characterized by mechanisms of competition and predation, akin to the animal world. However, while predation's ecological role is well-established in animals, it's less understood in bacteria due to fewer known predators and unclear phylogenetic affiliations. Nevertheless, microorganisms can prey on bacterial cells, including Bacteriophages, Protists, and Predatory Prokaryotes. These predators inhabit various habitats and may play vital roles in bacterial ecology and ecosystem regulation. Predatory interactions between host and parasite are common in nature. Predatory bacteria, such as Bdellovibrio and like organisms (BALOs), employ various strategies, including epibiotic predation and direct invasion. BALOs, which thrive in the periplasmic space of Gram-negative bacterial cells, modulate bacterial populations and could serve as preventive or therapeutic agents against Gram-negative infections. While primarily active against extracellular prey, BALOs may also target mitochondria, which are crucial for cellular processes. The relationship between intracellular bacteria and host mitochondria, including morphology, function, and apoptosis, warrants further exploration. Protocols for growing, propagating, and detecting predatory activities of BALOs, particularly Bdellovibrio bacteriovorus, are provided to assess their presence and activities against potential prey
Assessment of adhering and invading properties of Escherichia coli strains
No full textGastrointestinal infections, caused by Enterobacteriaceae, pose a major global health challenge, resulting in significant morbidity and mortality. Enhanced adherence and invasion properties are widespread among enteric pathogenic species, particularly those linked to invasive infections such as some pathovars of Escherichia coli or pathogens like Shigella and Salmonella. Pathogenic E. coli strains are categorized into various pathotypes, including diarrheagenic E. coli (DEC) and extraintestinal pathogenic E. coli (ExPEC). Notably, Enteroinvasive E. coli (EIEC) and Adherent-invasive E. coli (AIEC) demonstrate significant invasive properties. EIEC, similar to Shigella, invades intestinal epithelial cells causing dysentery-like illness, while AIEC persists in the gut epithelium, potentially contributing to chronic inflammatory bowel diseases (IBD). Techniques like cell culture assays are vital for assessing E. coli's adherence and invasion capabilities, with specific virulence factors such as fimbriae and type III secretion systems (T3SS) playing crucial roles. Comparatively, Shigella and Salmonella also utilize T3SS for epithelial cell invasion, but with distinct effector proteins and mechanisms. Understanding these differences is crucial for diagnosis and treatment, as advanced molecular diagnostics improve the identification of invasive E. coli strains. Potential therapeutic interventions targeting fimbrial adherence, T3SS and effector proteins offer promising avenues for developing antivirulence drugs. Here are provided protocols for studying the adherence and invasion properties of E. coli and other Enterobacteriaceae to enhance diagnostic methods, ultimately improving the management of enteric infections
Swimming and rafting of E.coli microcolonies at air–liquid interfaces
Full text linkThe dynamics of swimming microorganisms is strongly affected by solid-liquid and air-liquid interfaces. In this paper, we characterize the motion of both single bacteria and microcolonies at an air-liquid interface. Both of them follow circular trajectories. Single bacteria preferentially show a counter-clockwise motion, in agreement with previous experimental and theoretical findings. Instead, no preferential rotation direction is observed for microcolonies suggesting that their motion is due to a different physical mechanism. We propose a simple mechanical model where the microcolonies move like rafts constrained to the air-liquid interface. Finally, we observed that the microcolony growth is due to the aggregation of colliding single-swimmers, suggesting that the microcolony formation resembles a condensation process where the first nucleus originates by the collision between two single-swimmers. Implications of microcolony splitting and aggregation on biofilm growth and dispersion at air-liquid interface are discussed
INFLUENCE OF ORAL CONDITIONS ON COLONIZATION BY HIGHLY TOXIGENIC STAPHYLOCOCCUS AUREUS STRAINS
No full textOBJECTIVES: As the oral cavity is regarded as a relevant
site for Staphylococcus aureus colonization and interhu-
man transmission, this study aimed to investigate whether
different oral conditions influence the rates of S. aureus
oral carriage and genetic characters of S. aureus isolates.
SUBJECTS AND METHODS: Staphylococcus aureus was
searched in samples collected from cheek, gingival mar-
gin, and anterior nares of 45 healthy subjects, 27 peri-
odontitis affected subjects, and 29 subjects with fixed
prosthetic restorations. Isolates were screened for 17
genetic determinants, and Partial Least Square Discri-
minant Analysis was performed to evaluate whether
specific characters correlated with oral condition or site
of isolation.
RESULTS: The three subject groups showed comparable
nasal carriage rates but, both the periodontitis and
prosthetic restoration groups showed significantly higher
oral carriage rates, as compared to healthy subjects
(P = 0.01 and 0.02, respectively). Moreover, periodontitis
affected subjects hosted strains possessing a distinct
genotypic and phenotypic background, characterized by
the presence of a larger number of exotoxins encoding
genes.
CONCLUSIONS: These data confirm that the oral cavity
is an important site of S. aureus colonization and dem-
onstrate that conditions modifying the oral environment,
as the presence of periodontitis and of fixed prosthetic
restorations, promote S. aureus carriage and may favor
the spread of more pathogenic strains
Celiac children at diagnosis and after gluten-free diet: dominant mucosa-associated microbiota
No full text
Optimizing an array of self adapted temperature modulated metal oxide sensors for biomedical application
No full textIn the last years, we introduced a method aimed at creating a self-adaptive temperature profile that is generated by the sensor itself according to the characteristics of the sample at which it is exposed. Starting from the preliminary experimental evidences, in this work we introduced a novel baseline drift counteraction method to improve the stability of the responses of an array of three commercial self-adapted temperature modulation gas sensors. To further validate the proposed method, we have considered two experiments. In the first experiment, the performances of the proposed method have been compared with those obtained with the standard modulation as thermal ramp in the identification of three volatile compounds (Carbon monoxide, Hydrogen, Methane) at different concentrations. In the second experiment the proposed approach has been tested in the discrimination of three different bacteria strain culture lines
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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