1,721,002 research outputs found
Translational research into the effects of cigarette smoke on inflammatory mediators and epithelial TRPV1 in Crohn’s disease
Full text linkCrohn's disease is a pathological condition of the gastro-intestinal tract, causing severe transmural inflammation in the ileum and/or colon. Cigarette smoking is one of the best known environmental risk factors for the development of Crohn's disease. Nevertheless, very little is known about the effect of prolonged cigarette smoke exposure on inflammatory modulators in the gut. We examined the effect of cigarette smoke on cytokine profiles in the healthy and inflamed gut of human subjects and in the trinitrobenzene sulphonic acid mouse model, which mimics distal Crohn-like colitis. In addition, the effect of cigarette smoke on epithelial expression of transient receptor potential channels and their concurrent increase with cigarette smoke-augmented cytokine production was investigated. Active smoking was associated with increasedIL-8transcription in ileum of controls (p < 0,001; n = 18-20/group). In the ileum, TRPV1 mRNA levels were decreased in never smoking Crohn's disease patients compared to healthy subjects (p <0,001; n = 20/group). In the colon, TRPV1 mRNA levels were decreased (p = 0,046) in smoking healthy controls (n = 20/group). Likewise, healthy mice chronically exposed to cigarette smoke (n = 10/group) showed elevated ilealCxcl2(p = 0,0075) and colonicKcmRNA levels (p = 0,0186), whereas TRPV1 mRNA and protein levels were elevated in the ileum (p = 0,0315). Although cigarette smoke exposure prior to trinitrobenzene sulphonic acid administration did not alter disease activity, increased pro-inflammatory cytokine production was observed in the distal colon (Kc: p = 0,0273; Cxcl2: p = 0,104; Il1-beta: p = 0,0796), in parallel with the increase ofTrpv1mRNA (p < 0,001). We infer that CS affects pro-inflammatory cytokine expression in healthy and inflamed gut, and that the simultaneous modulation of TRPV1 may point to a potential involvement of TRPV1 in cigarette smoke-induced production of inflammatory mediators
Toxicological impact of food contaminants at the intestinal and hepatic levels
No full textCette thèse examine les effets toxicologiques de contaminants alimentaires au niveau intestinal et hépatique sur des modèles murins.Dans le premier chapitre, une revue de la littérature détaille l'organisation et les fonctions du système digestif, en mettant particulièrement l'accent sur l'intestin et le foie, ainsi que sur certaines pathologies associées. Cette exploration s'accompagne d'une description de l'omniprésence des contaminants dans notre alimentation et de leur impact sur notre santé.Dans un deuxième chapitre, l'attention est portée sur la mycotoxine déoxynivalénol, un contaminant fréquent des produits céréaliers, et son impact sur l'inflammation intestinale et le cancer colorectal. Les résultats montrent que le déoxynivalénol aggrave l'entérite induite par l'indométacine et favorise le développement du cancer colorectal associé à la colite. De plus, des altérations du microbiote intestinal et du métabolisme bactérien sont observées.Le troisième chapitre se concentre sur les effets des microplastiques de polyéthylène, qui représentent l'un des contaminants alimentaires émergents de ces dernières années. Les résultats indiquent que ces microplastiques altèrent la composition du microbiote intestinal ainsi que les réponses inflammatoires de l'intestin. Au niveau hépatique, les microplastiques exacerbent les processus inflammatoires et fibrotiques, notamment dans le contexte de la fibrose hépatique induite par le tétrachlorure de carbone.En résumé, cette thèse met en évidence les effets néfastes de certains contaminants alimentaires sur l'intestin et le foie. Ces résultats soulignent l'importance de prévenir et de gérer les risques associés aux contaminants alimentaires afin de préserver la santé gastro-intestinale et hépatique chez l'homme.This thesis examines the toxicological effects of dietary contaminants on the intestinal and hepatic levels using murine models.In the first chapter, a literature review details the organization and functions of the digestive system, with a particular focus on the intestine and the liver, as well as certain associated pathologies. This exploration is accompanied by a description of the omnipresence of contaminants in our diet and their impact on our health.In the second chapter, attention is focused on the mycotoxin deoxynivalenol, a common contaminant in cereal products, and its impact on intestinal inflammation and colorectal cancer. The results demonstrate that deoxynivalenol exacerbates indomethacin-induced enteritis and promotes the development of colorectal cancer associated with colitis. Additionally, alterations in the intestinal microbiota and bacterial metabolism are observed. The third chapter centers on the effects of polyethylene microplastics, which represent one of the emerging dietary contaminants in recent years. The results indicate that these microplastics alter the composition of the intestinal microbiota as well as the inflammatory responses in the intestine. At the hepatic level, microplastics exacerbate inflammatory and fibrotic processes, particularly in the context of carbon tetrachloride-induced hepatic fibrosis. In summary, this thesis highlights the adverse effects of certain dietary contaminants on the intestine and the liver. These findings emphasize the importance of preventing and managing the risks associated with dietary contaminants to preserve gastrointestinal and hepatic health in humans
Immunotoxicity and intestinal effects of nano- and microplastics: a review of the literature
No full textBackground Together with poor biodegradability and insufficient recycling, the massive production and use of plastics have led to widespread environmental contamination by nano- and microplastics. These particles accumulate across ecosystems - even in the most remote habitats - and are transferred through food chains, leading to inevitable human ingestion, that adds to the highest one due to food processes and packaging. Objective The present review aimed at providing a comprehensive overview of current knowledge regarding the effects of nano- and microplastics on intestinal homeostasis. Methods We conducted a literature search focused on the in vivo effects of nano- and microplastics on gut epithelium and microbiota, as well as on immune response. Results Numerous animal studies have shown that exposure to nano- and microplastics leads to impairments in oxidative and inflammatory intestinal balance, and disruption of the gut’s epithelial permeability. Other notable effects of nano- and microplastic exposure include dysbiosis (changes in the gut microbiota) and immune cell toxicity. Moreover, microplastics contain additives, adsorb contaminants, and may promote the growth of bacterial pathogens on their surfaces: they are potential carriers of intestinal toxicants and pathogens that can potentially lead to further adverse effects. Conclusion Despite the scarcity of reports directly relevant to human, this review brings together a growing body of evidence showing that nano- and microplastic exposure disturbs the gut microbiota and critical intestinal functions. Such effects may promote the development of chronic immune disorders. Further investigation of this threat to human health is warranted
Gut: An underestimated target organ for Aluminum.
No full textInternational audienceSince World War II, several factors such as an impressive industrial growth, an enhanced environmental bioavailability and intensified food consumption have contributed to a significant amplification of human exposure to aluminum. Aluminum is particularly present in food, beverages, some drugs and airbone dust. In our food, aluminum is superimposed via additives and cooking utensils. Therefore, the tolerable intake of aluminum is exceeded for a significant part of the world population, especially in children who are more vulnerable to toxic effects of pollutants than adults. Faced with this oral aluminum influx, intestinal tract is an essential barrier, especially as 38% of ingested aluminum accumulates at the intestinal mucosa. Although still poorly documented to date, the impact of oral exposure to aluminum in conditions relevant to real human exposure appears to be deleterious for gut homeostasis. Aluminum ingestion affects the regulation of the permeability, the microflora and the immune function of intestine. Nowadays, several arguments are consistent with an involvement of aluminum as an environmental risk factor for inflammatory bowel diseases.Depuis la seconde guerre mondiale, plusieurs facteurs tels qu’un essor industriel impressionnant, une augmentation de la bio-accessibilité environnementale et un accroissement de la consommation alimentaire ont contribué à une amplification importante de l’exposition humaine à l’aluminium. L’aluminium est notamment présent dans la nourriture, les boissons, certains médicaments et dans les poussières atmosphériques. Dans notre alimentation, de l’aluminium se surajoute via les additifs et les ustensiles de cuisine. Par conséquent, la dose tolérable d’aluminium est dépassée pour une part significative de la population mondiale, particulièrement chez les enfants qui sont plus vulnérables aux effets toxiques des polluants que les adultes. Face à cet afflux d’aluminium par voie orale, le tractus intestinal constitue une barrière essentielle, d’autant que 38 % de l’aluminium ingéré s’accumulent au niveau de la muqueuse intestinale. Bien qu’encore peu documenté à ce jour, l’impact de l’exposition orale à l’aluminium en conditions pertinentes par rapport à une exposition humaine réelle semble être délétère pour l’homéostasie de l’intestin. L’ingestion d’aluminium affecte la régulation de la perméabilité, de la microflore et de la fonction immunitaire de l’intestin. De nombreux arguments concordent aujourd’hui vers une implication de l’aluminium en tant que facteur de risque environnemental pour les maladies inflammatoires chroniques de l’intestin
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
Review article: epidemiological and animal evidence for the role of air pollution in intestinal diseases
No full textInternational audienceBACKGROUND: Ambient air pollution is recognized as one of the leading causes of global burden of disease. Involvement of air pollution in respiratory and cardiovascular diseases was first recognized, and then cumulative data has indicated that the intestinal tract could be also damaged.OBJECTIVE: To review and discuss the current epidemiological and animal data on the effects of air pollution on intestinal homeostasis.METHODS: An extensive literature search was conducted using Google Scholar and Pubmed to gather relevant human and animal studies that have reported the effects of any air pollutant on the intestine.RESULTS: Exposure to several gaseous and particulate matter components of air pollution have been associated either positively or negatively with the onset of various intestinal diseases including appendicitis, gastroenteric disorders, irritable bowel syndrome, inflammatory bowel diseases, and peptic ulcers. Several atmospheric pollutants have been associated with modifications of gut microbiota in humans. Animal studies have showed that inhalation of atmospheric particulate matter can lead to modifications of gut microbiota, impairments of oxidative and inflammatory intestinal balances, and disruption of gut epithelial permeability.CONCLUSIONS: Overall, the literature appears to indicate that the gut is an underestimated target of adverse health effects induced by air pollution. It is therefore important to develop additional studies that aim to better understand the link between air pollutants and gastro-intestinal diseases
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
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