16 research outputs found
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In Vitro Fermentation of NUTRIOSE® FB06, a wheat dextrin soluble fibre, in a continuous culture human colonic model system
Wheat dextrin soluble fibre may have metabolic and health benefits, potentially acting via mechanisms governed by the selective modulation of the human gut microbiota. Our aim was to examine the impact of wheat dextrin on the composition and metabolic activity of the gut microbiota. We used a validated in vitro three-stage continuous culture human colonic model (gut model) system comprised of vessels simulating anatomical regions of the human colon. To mimic human ingestion, 7 g of wheat dextrin (NUTRIOSE® FB06) was administered to three gut models, twice daily at 10.00 and 15.00, for a total of 18 days. Samples were collected and analysed for microbial composition and organic acid concentrations by 16S rRNA-based fluorescence in situ hybridisation and gas chromatography approaches, respectively. Wheat dextrin mediated a significant increase in total bacteria in vessels simulating the transverse and distal colon, and a significant increase in key butyrate-producing bacteria Clostridium cluster XIVa and Roseburia genus in all vessels of the gut model. The production of principal short-chain fatty acids, acetate, propionate and butyrate, which have been purported to have protective, trophic and metabolic host benefits, were increased. Specifically, wheat dextrin fermentation had a significant butyrogenic effect in all vessels of the gut model and significantly increased production of acetate (vessels 2 and 3) and propionate (vessel 3), simulating the transverse and distal regions of the human colon, respectively. In conclusion, wheat dextrin NUTRIOSE® FB06 is selectively fermented in vitro by Clostridium cluster XIVa and Roseburia genus and beneficially alters the metabolic profile of the human gut microbiota
Investigation of Autonomic Function and Orocecal Transit Time in-Patients With Nonalcoholic Cirrhosis and the Potential Influence of These Factors on Disease Outcome
Background: The presence of autonomic dysfunction in nonalcoholic cirrhosis and its influence on intestinal transit and disease outcome still need clarification. Goals: To investigate the function of the autonomic nervous system in patients with nonalcoholic cirrhosis and the possible associations among autonomic dysfunction, severity of liver disease, disturbed intestinal transit, and the development of complications during follow-up. Study: Measurements of heart rate variability obtained by analysis of 24-hour ambulatory electrocardiographic recordings to assess autonomic function and lactulose breath hydrogen test to determine orocecal transit time were performed in 32 patients with nonalcoholic cirrhosis divided into Child A and B. Results: Child B patients showed significantly lower values (P < 0.05) of those parameters reflecting parasympathetic (high frequency, log-transformed high frequency, pNN50) and sympathetic function (low frequency, log-transformed low frequency) in comparison with controls and Child A patients. Orocecal transit time values were significantly (P = 0.02) higher in Child B patients than in controls, but no relationship was found between delayed orocecal transit time and autonomic dysfunction. During follow-up, 42% of Child B patients developed encephalopathy. This complication was significantly associated with autonomic dysfunction. In addition, in the 4 patients who died the parameters reflecting parasympathetic function were significantly reduced in comparison with those of survivors. Conclusions: Autonomic dysfunction and delayed intestinal transit are related to the severity of disease in nonalcoholic cirrhosis. Autonomic dysfunction seems to predispose cirrhotic patients to the development of encephalopathy and tray be associated with a poor prognosis of these patients.43988488
MnO<sub>2</sub>-Ir Nanowires:Combining Ultrasmall Nanoparticle Sizes, O-Vacancies, and Low Noble-Metal Loading with Improved Activities towards the Oxygen Reduction Reaction
Although clean energy generation utilizing the Oxygen Reduction Reaction (ORR) can be considered a promising strategy, this approach remains challenging by the dependence on high loadings of noble metals, mainly Platinum (Pt). Therefore, efforts have been directed to develop new and efficient electrocatalysts that could decrease the Pt content (e.g., by nanotechnology tools or alloying) or replace them completely in these systems. The present investigation shows that high catalytic activity can be reached towards the ORR by employing 1.8 ± 0.7 nm Ir nanoparticles (NPs) deposited onto MnO2 nanowires surface under low Ir loadings (1.2 wt.%). Interestingly, we observed that the MnO2-Ir nanohybrid presented high catalytic activity for the ORR close to commercial Pt/C (20.0 wt.% of Pt), indicating that it could obtain efficient performance using a simple synthetic procedure. The MnO2-Ir electrocatalyst also showed improved stability relative to commercial Pt/C, in which only a slight activity loss was observed after 50 reaction cycles. Considering our findings, the superior performance delivered by the MnO2-Ir nanohybrid may be related to (i) the significant concentration of reduced Mn3+ species, leading to increased concentration of oxygen vacancies at its surface; (ii) the presence of strong metal-support interactions (SMSI), in which the electronic effect between MnOx and Ir may enhance the ORR process; and (iii) the unique structure comprised by Ir ultrasmall sizes at the nanowire surface that enable the exposure of high energy surface/facets, high surface-to-volume ratios, and their uniform dispersion