1,720,974 research outputs found
Jejunal and ileal nutrient uptake and epithelium integrity in pigs differing in protein efficiency
No full textProtein efficiency (PE) improvement is essential to develop sustainable pig production. The inefficient use of dietary protein by the animal results in excess excretion of unused protein that contributes to ammonia pollution. This study hypothesized that PE depends on a range of physiological processes such as intestinal amino acid uptake or the intestinal epithelial integrity in the pig. Thirty one Swiss Large White pigs (13 females and 18 castrated males)
were reared until an average body weight (BW) of 22.5 kg (±1.6 kg) and subsequently allocated to a pen where they remained until slaughter (BW 106±5 kg). Pigs had ad libitum access to a protein-reduced grower and finisher diet and water. For the ex vivo evaluation, jejunum segments from the third meter distal to the pylorus were removed within 15 min after exsanguination. Tissues were stripped of outer muscle layers and mounted in Ussing hambers. Trans epithelial difference (TEER) and short-circuit current (Isc) were continuously monitored. To evaluate L-Glutamate (L-Glut), L-Arginine (L-Arg) and D-Glucose (D-Gluc) uptake, tissues were equilibrated for 20 min before the mucosal addition of 5 mM L-Glut, followed by the addition of L-Arg, L-Meth and D-Gluc at the same concentration every 15 min. Simple linear models were run in R V 4.1.2 using lm() to investigate the influence of Isc, TEER, D-Glut, L-Arg and D-Gluc with PE, respectively. Sex did not influence any of the measured parameters. The TEER showed a negative relationship (P=0.009, R2=0.21) with PE, while no relationships were found between PE and amino acids uptake. A significant positive relationship between PE and D-Gluc uptake was also found (P=0.048, R2=0.14). The TEER strongly depends on the tight junction protein (TJs) expression. Further analysis are planned to investigate the intestinal TJs protein expression. Similarly, the protein expression of D-Gluc transporters will be the subject of future studies to clarify the correlation between PE and D-Gluc active transpor
Review: Harmonised in vitro digestion and the Ussing chamber for investigating the effects of polyphenols on intestinal physiology in monogastrics and ruminants
Full text linkBecause of the relevant effects of plant-derived polyphenols (PPs) on monogastrics and ruminants’ nutrition, emissions and performance, an increasing number of in vivo and in vitro studies are being performed to better understand the mechanisms of action of polyphenols at both the ruminal and intestinal levels. The biological properties of these phenolic compounds strongly depend on their degradation, absorption and metabolism. The harmonised in vitro digestion method (INFOGEST) is one of the most reliable in vitro methods used to assess the bioaccessibility and or antioxidant activity of PP contained in different matrixes, as well as the interactions of PP and their degradation products with other feed ingredients. The effects of PP released from their matrix after in vitro digestion on different intestinal physiological parameters, such as epithelium integrity, can be further evaluated by the use of ex vivo models such as the Ussing chamber. This review aims to describe the combination of the INFOGEST method, coupled with the Ussing chamber as a valuable model for the digestion and subsequent effects and absorption of phenolic compounds in monogastrics and potentially in ruminants. The advances, challenges and limits of this approach are also discussed
Investigating the mechanisms of action of conglutin-γ in regulating D-glucose uptake: the role of intestinal barrier
No full textConglutin-γ (Cg) is the major glycoprotein from the edible seed L. albus, long studied for its postprandial glycaemic regulating action. Several cell model systems (liver, pancreatic, myoblast, musculoskeletal) have been used to investigate in vitro mechanisms of action, all attributable to insulin-mimetic actions. However, it still lacks clear information on what could happen at the meeting point between the protein and the organism: the intestinal barrier.
We compared an in vitro system involving Caco2 and IPEC-J2 cells with an ex vivo system using pig jejunal segments to study Cg transport from the apical to the basolateral compartment, its effects on the D-glucose uptake and glucose transporters protein expression. Finally, we studied its potential in modulating glucose metabolism by assessing the possible inhibition of α-amylase and α-glucosidase. RP-HPLC analyses showed that Cg could be found in the basolateral side in the in vitro system but not in the pig intestines, where it causes tissue damage with albumin release. Cg dispensing was able to promote a decrease in glucose uptake in both cells and jejunum independently from the expression of the SGLT1 and GLUT2 transporter
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
Ellagic acid and gallic acid mitigate methane production in an in vitro model of rumen fermentation
No full textRuminant production accounts for 81% of greenhouse gas emissions in the livestock sector. Of this quantity, enteric
fermentation methane accounts for 90%. Dietary supplementation with tannins is known to mitigate methane
production, but also affect feed digestibility. The aim of this study was to investigate the effect of ellagic acid (EA) and
gallic acid (GA), alone or in combination, on rumen fermentation in a short-term in vitro experiment using Hohenheim
Gas Test. EA and GA were supplemented to a control diet (hay, 200 mg DM). Five different conditions were applied
to this study (% of DM): (1) EA 7.5; (2) EA 15; (3) GA 7.5; (4) GA 15; and (5) EA 7.5 + GA 7.5. After an incubation
of 24 h at 39 °C, pH, ammonia formation, gas production, short-chain fatty acids (SCFA), in vitro organic matter
digestibility (IVOMD) and the microbial count were determined. The treatments did not alter microbial count and pH.
Total SCFA production decreased by approximately 10% after all treatments (P<0.001). In the ruminal SCFA profile,
the differences were still significant (except for valeric acid) but less evident than total SCFA. Total gas production
slightly decreased (-10%) after all treatments, except for GA 7.5. EA 15 and EA+GA treatments decreased methane
production per g DM by 20 and 25%, respectively. These two treatments decreased by 10% the production of CO2
per g DM and the production of ammonia on DM basis, respectively by 13 and 20%. All the treatments caused a
slight but significant 10% reduction of IVOMD. In conclusion, diet supplementation with EA and GA, alone or in
combination, may be a promising dietary strategy to mitigate methane production in ruminants. Further long-term
in vitro ruminal fermentation studies are needed to validate these results, before assessing these treatments in vivo
Comparison of jejunum and ileum electrogenic transport and epithelium integrity in growing cattle from three different cross-breeds
Full text linkThe integrity of the gastro-intestinal tract and the intestinal absorption of nutrients may contribute to inter-individual variation in feed efficiency in beef cattle (Kenny et al., 2018). The aim of this study was to compare the intestinal epithelium integrity and the jejunum and ileum electrogenic transport in growing heifers from three different crossbreeds.
Material and Methods
Ethics committee of Switzerland approved all the procedures. Thirty growing heifers from three crossbreeding (Brown Swiss as dam and Limousin, Angus or Simmental as sire, n = 10 of each) were used. After weaning at the age of 2.5 months (mo), animals were fed according
to two type of grass-based diets and were slaughtered at different ages leading to five experimental treatments (n = 6 for each): Grass silage-based diet continuously, slaughtered at 200 ± 10 days old (GS-7mo); 350 ± 10 days (GS-11mo) or 470 ± 10 days (GS-15mo); or grass
silage-based diet until 7 mo and pasture only thereafter, slaughtered at 290 ± 10 days (PA-9mo) or 350 ± 10 days (PA-11mo). Intestinal segments from jejunum and ileum (210 cm and 5 cm cranium from ileo-cecal valve, respectively) were removed within 50 min after slaughter.
To evaluate L-Glutamate (L-Glut), L-Arginine (L-Arg), L-Methionine (L-Meth) and D-Glucose (D-Glu) uptakes across intestinal tissues, jeju num and ileum segments were mounted on Ussing chambers. The trans-epithelial potential difference (TEER) and short-circuit current (Isc)
were continuously monitored. Mucosal addition of 5 mM L-Glut was followed by the addition 15 min apart of L-Arg, L-Meth and D-Gluc at the same concentration.
The results were analyzed by ANOVA with the R software (v 4.0.5). Linear mixed-effects regression (lmer) models were used as mixed models. Model contained the crossbreed, tissue (jejunum vs ileum) and treatment as fixed effects and the animal as a random effect. The inter actions crossbreed tissue and tissue treatment were evaluated, while the interactions crossbreed treatment and crossbreedxtissuextreatment were not addressed due to the reduced number of observations. For pairwise comparisons, Sidak function was performed for a modified Tukey test for multiple comparisons of means. Means and SEM were reported from the lsmeans function from the package emmeans. Residuals of lmer models were checked for normality and homoscedasticity. For L-Glut and L-Meth, the values were logarithmic transformed.
Results and Discussion
Whatever the slaughter age and dietary treatment, the jejunum TEER of the Limousin
rossbreed was higher (P < 0.01) compared to the
jejunum and ileum of the Angus and Simmental crossbreeds. Conversely, none differences were observed according to crossbreed or treat ment in the amino acids and D-Glu uptakes (Table 1). The L-Arg uptake was lower (P = 0.01) in GS-7mo compared to GS-11mo, whatever
the tissue segment (Figure 1).
Conclusion and Implications
The TEER measurements constitute a method to monitor the barrier integrity of epithelial layers (Chen et al., 2015) and it mostly depends by tight-junctions integrity. The barrier function of tight-junctions regulates host nutrition, maintenance of homeostasis and protection of the host against pathogen invasion that can cause severe intestinal infection (Gareau et al., 2010). Therefore, based on these results, we speculate that the Limousin crossbred heifers could be less susceptible to gastrointestinal disorders and further analyses are planned to further investigate the differences between the three crossbreeds in the tight-junctions protein expression. The reasons and the implica tions of the increased L-Arg uptake for GS-11mo treatment and subsequent decrease after 4 mo on the same diet will be also the subject of future studies
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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