1,720,963 research outputs found
HPLC-MS-MS quantification of short-chain fatty acids actively secreted by probiotic strains
Full text linkIntroduction: Short-chain fatty acids (SCFAs) are the main by-products of microbial fermentations occurring in the human intestine and are directly involved in the host's physiological balance. As impaired gut concentrations of acetic, propionic, and butyric acids are often associated with systemic disorders, the administration of SCFA-producing microorganisms has been suggested as attractive approach to solve symptoms related to SCFA deficiency. Methods: In this research, nine probiotic strains (Bacillus clausii NR, OC, SIN, and T, Bacillus coagulans ATCC 7050, Bifidobacterium breve DSM 16604, Limosilactobacillus reuteri DSM 17938, Lacticaseibacillus rhamnosus ATCC 53103, and Saccharomyces boulardii CNCM I-745) commonly included in commercial formulations were tested for their ability to secrete SCFAs by using an improved protocol in high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS-MS). Results: The developed method was highly sensitive and specific, showing excellent limits of detection and quantification of secreted SCFAs. All tested microorganisms were shown to secrete acetic acid, with only B. clausii and S. boulardii additionally able to produce propionic and butyric acids. Quantitative differences in the secretion of SCFAs were also evidenced. Discussion: The experimental approach described in this study may contribute to the characterization of probiotics as SCFA-producing organisms, a crucial stage toward their application to improve SCFA deficiency
Analysis of the microbial content of probiotic products commercialized worldwide and survivability in conditions mimicking the human gut environment
Full text linkIntroduction: Probiotics are living microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Adequate number of living microbes, the presence of specific microorganisms, and their survival in the gastrointestinal (GI) environment are important to achieve desired health benefits of probiotic products. In this in vitro study, 21 leading probiotic formulations commercialized worldwide were evaluated for their microbial content and survivability in simulated GI conditions. Methods: Plate-count method was used to determine the amount of living microbes contained in the products. Culture-dependent Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry and culture-independent metagenomic analysis through 16S and 18S rDNA sequencing were applied in combination for species identification. To estimate the potential survivability of the microorganisms contained in the products in the harsh GI environment, an in vitro model composed of different simulated gastric and intestinal fluids was adopted. Results: The majority of the tested probiotic products were concordant with the labels in terms of number of viable microbes and contained probiotic species. However, one product included fewer viable microbes than those displayed on the label, one product contained two species that were not declared, and another product lacked one of the labeled probiotic strains. Survivability in simulated acidic and alkaline GI fluids was highly variable depending on the composition of the products. The microorganisms contained in four products survived in both acidic and alkaline environments. For one of these products, microorganisms also appeared to grow in the alkaline environment. Conclusion: This in vitro study demonstrates that most globally commercialized probiotic products are consistent with the claims described on their labels with respect to the number and species of the contained microbes. Evaluated probiotics generally performed well in survivability tests, although viability of microbes in simulated gastric and intestinal environments showed large variability. Although the results obtained in this study indicate a good quality of the tested formulations, it is important to stress that stringent quality controls of probiotic products should always be performed to provide optimal health benefits for the host
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
Caratterizzazione di una formulazione probiotica a base di Enterococcus e suoi effetti sul microbiota intestinale di topi obesi
No full textNegli ultimi decenni, i microrganismi con attività probiotiche hanno suscitato un interesse sempre maggiore nella comunità scientifica per le loro proprietà fisiologiche benefiche, i complessi meccanismi d’azione da loro esplicati nell’ospite e la loro capacità di modulare positivamente il microbiota intestinale alterato in numerosi disordini e stati patologici dell’uomo. In questo contesto, gli obiettivi del presente progetto di tesi sono stati quelli di caratterizzare sotto molteplici aspetti una formulazione probiotica a base di batteri appartenenti al genere Enterococcus e, in secondo luogo, di valutare gli effetti della sua somministrazione sul microbiota intestinale in un modello murino di obesità.
La caratterizzazione della formulazione probiotica è servita, innanzitutto, per verificare che la quantità di microrganismi all’interno della formulazione e la varietà di specie microbiche presenti fossero concordi con quanto dichiarato sull’etichetta del prodotto commercializzato. Per ottenere un’indicazione del numero di microrganismi vitali nel prodotto, è stata effettuata una conta vitale delle CFU. Per l’identificazione dei microrganismi, alcune colonie isolate sono state prelevate e sottoposte a spettrometria di massa MALDI-TOF. Dalla formulazione è stato estratto il DNA genomico, che è stato sottoposto a sequenziamento del gene codificante per l’rRNA 16S batterico per escludere la presenza di contaminazione nella formulazione da parte di altri ceppi microbici. Da queste analisi è risultato che la formulazione probiotica è conforme in quantità e qualità rispetto a quanto dichiarato dall’azienda produttrice. È stata saggiata, inoltre, la capacità dei microrganismi di sopravvivere in succhi gastrici e intestinali artificiali, tramite incubazione del prodotto nel fluido artificiale e semina di aliquote della sospensione microbica su piastre di agar sangue a diversi tempi di incubazione. La conta delle CFU ottenute, confrontata con quella rilevata nella iniziale conta vitale, ha permesso di determinare se i microrganismi costituenti la formulazione fossero in grado di sopravvivere in condizioni paragonabili a quelle presenti in vivo nell’apparato gastrointestinale. I risultati ottenuti hanno rivelato la presenza di un numero di microrganismi più elevato rispetto a quanto dichiarato in etichetta, mentre l’identificazione a livello di genere e specie è risultata idonea. I saggi di resistenza al succo gastrico artificiale hanno denotato una scarsa percentuale di sopravvivenza dei microrganismi ad un pH di 1.5, che aumenta però ad un pH di 3.0. I saggi di sopravvivenza in succo intestinale artificiale, infine, hanno dimostrato un’elevata sopravvivenza dei batteri in questo mezzo.
La formulazione probiotica è stata poi somministrata per via orale a topi ai quali è stato imposto un regime alimentare standard (standard diet, SD) o ad alto contenuto di grassi (high-fat diet, HFD). Dalle feci di questi animali è stato estratto il DNA genomico, che è stato successivamente sottoposto a Real-time PCR quantitativa al fine di rilevare l’abbondanza assoluta di specifici phyla e generi batterici costituenti il microbiota intestinale degli animali. I risultati ottenuti hanno permesso di dimostrare che la somministrazione del prodotto probiotico determina variazioni significative della composizione del microbiota intestinale. Tra le principali differenze osservate tra topi alimentati con dieta standard e quelli con dieta HFD è stato riscontrato un aumento nell’abbondanza dei microrganismi appartenenti al phylum Firmicutes e al genere Faecalibacterium, mentre per i generi Bacteroides e Prevotella è stata osservata una diminuzione. È stata poi evidenziata una riduzione nella quantità di microrganismi appartenenti ai generi Bacteroides, Prevotella e al phylum Firmicutes tra i topi normopeso che avevano ricevuto il probiotico per 4 settimane e quelli a cui non era stato somministrato il trattamento. Per quanto riguarda la comparazione tra i topi obesi a cui non era stato somministrato il probiotico e quelli che lo avevano ricevuto, negli animali trattati con la formulazione probiotica è stata osservata una diminuzione nel numero di microrganismi appartenenti ai phyla Firmicutes e Proteobacteria, mentre per il genere Bifidobacterium è stato riscontrato un aumento
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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