1,720,995 research outputs found
Odorant binding protein has the biochemical properties of a scavenger for 4-hydroxy-2-nonenal in mammalian nasal mucosa.
No full textOdorant binding proteins (OBP) are soluble lipocalins produced in large amounts in the nasal mucosa of several mammalian species. Although OBPs can bind a large variety of odorous compounds, direct and exclusive involvement of these proteins in olfactory perception has not been clearly demonstrated. This study investigated the binding properties and chemical resistance of OBP to the chemically reactive lipid peroxidation end-product 4-hydroxy-2-nonenal (HNE), in an attempt to establish a functional relationship between this protein and the molecular mechanisms combating free radical cellular damage. Experiments were carried out on recombinant porcine and bovine OBPs and results showed that both forms were able to bind HNE with affinities comparable with those of typical OBP ligands (K(d) = 4.9 and 9.0 microm for porcine and bovine OBP, respectively). Furthermore, OBP functionality, as determined by measuring the binding of the fluorescent ligand 1-aminoanthracene, was partially lost only when incubating HNE levels and exposure time to HNE exceeded physiological values in nasal mucosa. Finally, preliminary experiments in a simplified model resembling nasal epithelium showed that extracellular OBP can preserve the viability of an epithelial cell line derived from bovine turbinates exposed to toxic amounts of the aldehyde. These results suggest that OBP, which is expressed at millimolar levels, might reduce HNE toxicity by removing from the nasal mucus a significant fraction of the aldehyde that is produced as a consequence of direct exposure to the oxygen present in inhaled air
A novel IncA plasmid carrying blaVIM-1 in a Kluyvera cryocrescens strain
No full textKluyvera is considered a benign saprophyte commonly present in the environment and also in the human gastrointestinal tract. Kluyvera infections in humans are rare and the pathogenic role of Kluyvera remains uncertain.1 In recent years, sporadic cases of Kluyvera species carrying class A carbapenemase genes (blaGES-5 and blaKPC-2) have been reported.2,3
Herein we describe the complete nucleotide sequence of an IncA plasmid carrying blaVIM-1 recovered from a Kluyvera cryocrescens strain isolated in Italy. This is, to our knowledge, the first report about a Kluyvera strain with an acquired class B carbapenemase
Extensively drug-resistant Acinetobacter baumannii isolated from intensive care units in Northern Italy: a genomic approach to characterize new sequence types.
No full textAim: This study aims to characterize clinical strains of Acinetobacter baumannii with an extensively drug-resistant phenotype. Methods: VITEK® 2, Etest® method and broth microdilution method for colistin were used. PCR analysis and multilocus sequence typing Pasteur scheme were performed to identify bla-OXA genes and genetic relatedness, respectively. Whole genome sequencing analysis was used to characterize three isolates. Results: All the isolates were susceptible only to polymyxins. blaOXA-23-like gene was the only acquired carbapenemase gene in the 88.2% of the isolates. Multilocus sequence typing identified various sequence types: ST2, ST19, ST195, ST577 and ST632. Two new sequence types, namely, ST1279 and ST1280, were detected by whole genome sequencing. Conclusion: This study showed that carbapenem-resistant A. baumannii isolates causing infections in intensive care units almost exclusively produce OXA-23, underlining their frequent spread in Italy
Characterization of an IncL/M plasmid carrying blaOXA-48 in a Klebsiella pneumoniae strain from Italy
No full textHere we report the complete nucleotide sequence of a 49.257-bp IncL/M conjugative plasmid (pRAY) carrying the blaOXA-48 gene collected from a Klebsiella pneumoniae clinical strain isolated in Italy. The genetic environment of pRAY plasmid revealed that the blaOXA-48 gene was located within a Tn1999.2 transposon. The pRAY plasmid differed from blaOXA-48-harboring IncL/M plasmids by genetic context and size. Comparative analysis demonstrated that pRAY plasmid lacked a region of ~15 kb carrying genes encoding proteins involved in pilus assembly and plasmid conjugative apparatus
Emergence of Pandemic Clonal Lineage Sequence Types 131 and 69 of Extraintestinal Escherichia coli as a Cause of Meningitis: Is It Time To Revise Molecular Assays?
No full text: Two Escherichia coli strains, respectively responsible for neonatal and adult meningitis, were isolated and their phenotypic antibiotic susceptibility and genomic features characterized by whole-genome sequencing (WGS). Multiplex real-time PCR targeting the principal microorganisms involved in meningitis etiology failed to identify either isolate. Afterwards, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry was used to identify the isolates as E. coli strains. Genomic analysis showed that they belonged to sequence types 131 and 69 (ST131 and ST69). Neither of the isolates harbored the K1 capsular antigen or belonged to other capsular serotypes, but they shared different virulence factors, including ibe genes, responsible for invasion of brain endothelial cells. IMPORTANCE The extraintestinal pathogenic Escherichia coli group is characterized by the presence of uropathogenic E. coli (UPEC), sepsis-associated E. coli (SEPEC), and neonatal meningitis E. coli (NMEC). All of these members exhibit many virulence factors, such as lipopolysaccharides, toxins, iron acquisition factors, invasins, fimbriae, and capsules. Urinary infections are the most common infections caused by this group, followed by globally increasing numbers of both community- and nosocomially acquired bloodstream infections, associated with considerable patient morbidity and mortality. Some lineages tend to become dominant; in addition to enhanced fitness, this epidemiological success stems from increased virulence, antibiotic resistance, gut colonization, and greater host-to-host transmission. Our results underline the importance of continuous surveillance of these new emerging lineages and the need to develop new meningitis molecular assay panels able to identify them
From dairy products to molecular mechanisms: characterization of Lactococcus lactis phage proteins involved in Homologous Recombination and Abortive Infection systems
No full textVirulent phages of the 936 and P335 group are predominant in nfections
of Lactococcus lactis, a Gram-positive bacterium widely used in the dairy industry. Among the strategies adopted by L. lactis against virus infection, pivotal roles are played by abortive infection mechanisms (Abi), but little is known about their molecular details. With regard to the AbiK system, four non-similar phage proteins, involved in the sensibility to AbiK and in homologous recombination replication,
were identified and named Sak (sensitive to AbiK). Here is presented
the biochemical and structural characterization of two of them: Sak from phage ul36, an homologue of the eukaryotic protein RAD52 with a clear DNA Single-Strand Annealing function (SSA proteins) and Sak3 from phage p2, the reference protein for the third group of identified sak genes that do not show significant sequence similarity to SSAPs. In addition, we report the three dimensional structure and functional characterization of a third protein, a phage p2 single-strand binding protein (SSB), which is a Sak3 partner in homologous recombination. With our investigation, we could establish, experimentally, a relationship between phage protein mediated DNA processing and L.lactis antiviral AbiK system
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
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