<p>  </p> <p>The world has experienced an unprecedented change in the systems responsible for food production, distribution, and commercialization with concurrent changes in diets. In developed and developing countries, the shift in consumption patterns has moved towards a Western diet pattern which has been linked to negative health outcomes including obesity, diabetes and associated non-communicable diseases. Traditional African diets have previously been associated with protective effects against the development of the above-mentioned conditions. Yet, the underlying reasons for this is not clear. One dietary factor that may contribute to its protective effect is the principal available carbohydrate, starch, which in traditional African staples is considered to contain slowly digestible carbohydrates (SDCs) and some amount of resistant starch (RS). We reported that traditional African staple starchy foods (sorghum and millet) had markedly slower gastric emptying than introduced modern starchy foods (rice, pasta and potatoes). This response was attributed to activation of enteroendocrine cells of the small intestine (L-cells) with potential to trigger physiological, hormonal, and neurological processes that affect digestion time and perception of hunger; effect known as the ileal brake. Moreover, at least in mice models, consumption of SDCs has shown to have beneficial effects on the rate and type of fuel (e.g. carbohydrate vs fat) used for metabolic processes.</p> <p>The first thesis study compared the effect of diets (cohorts in the USA and Kenya) on gastric half-emptying time and metabolic fuel utilization in healthy adults. Our findings showed that gastric emptying time was not different between cohorts and that diet did not influence gastric emptying time; however, calculated respiratory exchange ratio (RER) (which is a measure of metabolic fuel utilization at the cellular level, e.g. carbohydrate vs fat) and metabolic flexibility (which is the ability to switch between metabolic fuel sources upon demand or need) was higher for the Kenyan cohort. Multivariant models were developed and corrected for multicollinearity of some diet variables. Carbohydrate and protein in multivariate model 1; total fiber, added sugars and starch in multivariate model 2; and diet quality (measured as the Healthy Eating Index based on 2015-2020 dietary guidelines, or HEI-2015) in multivariate model 3, were significantly and independently correlated with RER and metabolic flexibility.   </p> <p>The second study assessed if slow gastric emptying and improve metabolic fuel utilization could be induced through SDC supplementation. The objective of this study was to determine if continual consumption of SDC for 21 days delayed the rate of gastric emptying, moderated postprandial glycemic response, decreased hunger, and/or improved metabolic fuel utilization in subjects with low diet quality (HEI-2015<65). Our results indicated that supplementation with SDC did not slow gastric emptying time or acute measures of metabolic fuel utilization; however, continuous consumption of SDC had a modest but significant effect on improving metabolic flexibility and decreasing hunger scores. </p> <p>The last two chapters of this thesis focused on the use of a low-cost, high-pressure, high temperature extruder suitable for processing in Africa of whole grain pearl millet (<em>Pennisetum glaucum</em>). In Africa, emerging, entrepreneurial companies are increasingly gaining share of local markets by manufacturing and distributing high-quality locally sourced processed foods made with indigenous grains. Whole pearl millet is particularly susceptible to development of rancidity. The objective of our third study was to assess the use of the extruder on the stability and sensory attributes of whole grain pearl millet extruded flours to be used for instant thin and thick porridges. Findings showed that extrusion fully gelatinized the starch in pearl millet and prevented hydrolytic rancidity in the instant flour products. However, extrusion cooking did not stop oxidative rancidity. We concluded that while extrusion cooking is a versatile technology for whole grain processing, refinement of extrusion conditions used in the experiment and the evaluation of other unit operations (e.g. steeping, germination) in combination with extrusion cooking may improve the sensory properties of final products.</p> <p>Finally, extrusion cooking has been showed to promote the formation of beneficial amylose-lipid complexes (ALCs). The objective of the last study was to evaluate the formation of ALCs in whole grain pearl millet extruded flours, characterize their composition, and assess their ability to slowly digest <em>in vitro</em>. Extrusion promoted the formation ALCs and these flours exhibited a slow enzymatic digestion <em>in vitro</em>. The findings from this thesis provide insights into the role of diets and metabolic fuel utilization, and improvement of processed pearl millet foods in Africa.</p>

No description available.

Yes / Background: Oral administration of purified omega-3 (ω-3) PUFAs is associated with changes to the fecal microbiome. However, it is not known whether this effect is associated with increased PUFA concentrations in the gut. Objectives: We investigated the luminal bioavailability of oral ω-3 PUFAs (daily dose 1 g EPA and 1g DHA free fatty acid equivalents as triglycerides in soft-gel capsules, twice daily) and changes to the gut microbiome, in the ileum. Methods: Ileostomy fluid (IF) and blood were obtained at baseline, after first capsule dosing (median 2 h), and at a similar time after final dosing on day 28, in 11 individuals (median age 63 y) with a temporary ileostomy. Fatty acids were measured by LC–tandem MS. The ileal microbiome was characterized by 16S rRNA PCR and Illumina sequencing. Results: There was a mean 6.0 ± 9.8-fold and 6.6 ± 9.6-fold increase in ileal EPA and DHA concentrations (primary outcome), respectively, at 28 d, which was associated with increased RBC ω-3 PUFA content (P ≤ 0.05). The first oral dose did not increase the ileal ω-3 PUFA concentration except in 4 individuals, who displayed high luminal EPA and DHA concentrations, which reduced to concentrations similar to the overall study population at day 28, suggesting physiological adaptation. Bacteroides, Clostridium, and Streptococcus were abundant bacterial genera in the ileum. Ileal microbiome variability over time and between individuals was large, with no consistent change associated with acute ω-3 PUFA dosing. However, high concentrations of EPA and DHA in IF on day 28 were associated with higher abundance of Bacteroides (r2 > 0.86, P < 0.05) and reduced abundance of other genera, including Actinomyces (r2 > 0.94, P < 0.05). Conclusions: Oral administration of ω-3 PUFAs leads to increased luminal ω-3 PUFA concentrations and changes to the microbiome, in the ileum of individuals with a temporary ileostomy.

Dietary protein quality depends on two key measures: true ileal protein digestibility and the metabolic utilization of absorbed amino acids (AA). The objectives of this study were to determine the influence of two dietary factors (antinutritional factors and peptides) on ileal endogenous protein flows; to validate the intubation technique used in humans for ileal digesta sampling; to determine the postprandial metabolic utilization of dietary AA depending on their delivery form and to assess the validity of the growing pig for predicting true ileal protein digestibility in the adult human. Investigations were undertaken in the growing rat, growing pig and adult human. Ileal digesta were collected from euthanised rats, post valve T-caecum cannulated pigs, and naso-ileal intubated conscious adult humans. Ileal endogenous nitrogen (N) and AA were measured using a protein-free (PF) diet, diets containing 15N-labelled casein in the intact (C) or hydrolysed (HC) form, or a diet based on free AA (diet A), for which some dispensable AA were omitted to allow a direct determination of their endogenous flows. Digesta centrifugation and ultrafiltration (diet HC) allowed for the determination of ileal endogenous protein flows and the extent of tracer (15N) recycling. Antinutritional factors from a crude extract of kidney beans (Phaseolus vulgaris), when given at amounts commonly ingested in practice, enhanced ileal endogenous protein flows (rats, PF diet). After adaptation to the diet, body N balance per se did not influence ileal endogenous protein flows (rats, diets PF and A) but dietary peptides led to greater ileal endogenous AA and N flows compared with a protein-free diet. Dietary peptides (HC), compared with peptides naturally released in the gut during protein digestion (C), did not enhance ileal endogenous protein flows (rats, pigs, and humans). The extent of tracer recycling, however, was maximal in frequently-fed rats, lower in meal-fed pigs and minimal in meal-fed humans (65, 21, and 11% of 15N-labelled ileal endogenous proteins, respectively). Naso-ileal intubation for ileal digesta sampling in humans was shown to be an accurate method and evidence was obtained supporting the growing pig as a valid model for predicting true ileal protein digestibility in the adult human. Finally, the form of delivery of dietary AA (from HC or C) influenced the postprandial metabolic fate of dietary AA, especially in terms of AA catabolism kinetics. However, the overall nutritional value of C and HC were similar.

Orientador: Nelson Adami Andreollo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-15T23:47:26Z (GMT). No. of bitstreams: 1 Braoios_MariaCristinaCostaResck_D.pdf: 3388857 bytes, checksum: 58550a8a6d4c3f121c9a3aa9185d24ae (MD5) Previous issue date: 2010 / Resumo: As gastroplastias e as derivações intestinais revolucionaram o tratamento da obesidade mórbida, pela sua viabilidade e resposta sustentada. Porém, estudos experimentais, sugerem após as derivações jejunoileais um aumento do risco de câncer de cólon devido ao aumento do tamanho e da proliferação das criptas intestinais. Evidências sugerem os possíveis efeitos antioxidantes na prevenção da carcinogênese que demonstram sua capacidade de neutralizar ou eliminar os radicais livres. O ácido ascórbico participa do processo de oxirredução das células, como também é importante na biossíntese de catecolaminas. Os compostos de nitrito e nitrato são sais empregados como conservantes de alimentos, que neste contexto do aumento de população mundial e escassez de alimentos, será cada vez mais empregado. Estes sais têm ação danosa ao organismo em situações específicas, como demonstram vários experimentos. O objetivo dessa pesquisa foi analisar as alterações histopatológicas caracterizadas pelo índice de mitoses produzidas no intestino grosso de ratos Wistar submetidos à derivação jejunoileal após administração continuada de vitamina C e nitrito de sódio, em diferentes grupos. Oitenta ratos machos Wistar pesando entre 450-550g foram divididos em doze grupos, com vinte animais controles não operados (5 animais ingeriram somente água, 5 animais ingeriram somente vitamina C, 5 animais ingeriram somente nitrito de sódio e 5 animais ingeriram vitamina C+nitrito de sódio). Sessenta animais foram anestesiados e submetidos à laparotomia mediana com exposição das alças intestinais. Em vinte animais apenas manipulação intestinal foi realizada, este servindo como sham. Nos restantes (grupo denominado operado), o intestino foi seccionado a 3cm da junção duodeno-jejunal, e a derivação jejunoileal foi realizada através da anastomose látero-lateral no íleo terminal a 2cm da válvula íleo-cecal. Os animais foram acondicionados em gaiolas com cinco animais cada de acordo com a droga que receberam. Após 180 dias de observação, os animais eram pesados semanalmente, e para análise foram divididos em segmentos (S1, S2, S3, S4 e S5) correspondentes ao ceco, colon ascendente, transverso, descendente e reto. No grupo controle, observando os segmentos em comparação ao tratamento (p< .0001) e comparando a média entre todos os segmentos (p=0,0323) indica que o nitrito+vitamina C obtiveram o menor índice de mitoses em relação aos outros tratamentos. No grupo operado os segmentos S1 e S2 houve diferença estatística com o tratamento vitamina C, o qual apresentou um maior índice de mitose e melhor preservação do epitélio. No grupo sham houve diferença apenas entre tratamento (p< .0001), não havendo diferença entre segmentos (p=0,0849) e nem interação entre segmento e tratamento (p=0.7135). A principal diferença estatística ficou apenas no grupo nitrito+vitamina C entre a média dos segmentos. Concluem que, comparando todos os segmentos colônicos avaliados dos vários grupos estudados, foi observado que os animais que receberam nitrito de sódio associado à vitamina C apresentaram menor índice de mitoses. Além disso, foi verificado que a vitamina C não apresentou um efeito inibidor, estatisticamente significativo, na preservação da mucosa e no índice de mitos / Abstract: Gastroplasty and intestinal bypass revolutionized the treatment of morbid obesity, the viability and sustained response. However, experimental studies suggest following the jejunoileal bypass increased risk of colon cancer due to the increased size and proliferation of intestinal crypts. Evidence suggests the possible effects of antioxidants in the prevention of carcinogenesis that demonstrate their ability to neutralize or eliminate free radicals. The ascorbic acid redox process of the cells, it is also important in the biosynthesis of catecholamines. The compounds of nitrite and nitrate salts are used as food preservatives, which in this context of increasing world population and food shortages, will be increasingly employed. These salts have a harmful action to the body in specific situations, as demonstrated by several experiments. The aim of this study was to evaluate the histopathological changes characterized by the index of mitosis produced in the intestine of rats subjected to jejunum-ileum bypass after continuous administration of vitamin C and sodium nitrite in different groups. Eighty male Wistar rats weighing 450-550g were divided into twelve groups, with twenty non-operated control animals (5 animals ingested only water, only 5 animals ate vitamin C, only 5 animals ingested sodium nitrite and 5 animals ate vitamin C + nitrite sodium). Sixty animals were anesthetized and underwent laparotomy with exposure of the bowel. In twenty animals only intestinal manipulation was performed, this serving as a sham. In the other (called the operated group), the intestine was cut to 3 cm from the duodenum-jejunal junction, and jejunum-ileum bypass was performed through the side-to-side anastomosis in the ileum 2 cm from the ileocecal valve. The animals were placed in cages with five animals each according to the drug they received. After 180 days of observation, the animals were weighed weekly, and for analysis were divided into segments (S1, S2, S3, S4 and S5) corresponding to the cecum, ascending colon, transverse, descending and rectum. In the control group, noting the segments in comparison to treatment (p <.0001) and comparing the average of all segments (p = 0.0323) indicates that nitrite + vitamin C obtained the lowest rate of mitosis in relation to other treatments. In the group operated the segments S1 and S2 was no statistical difference in treatment vitamin C, which showed a higher rate of mitosis and better preservation of the epithelium. In the sham group only showed a difference between treatment (p <.0001), with no difference between segments (p = 0.0849) nor interaction between segment and treatment (p = 0.7135). The main difference was statistically only for the nitrite + vitamin C between the average of the segments. They conclude that, comparing all colonic segments evaluated the various groups, it was observed that the animals that received sodium nitrite plus vitamin C had a lower rate of mitosis. Furthermore, it was found that vitamin C did not show an inhibitory effect was statistically significant to the preservation of the mucosa and the index of mitos / Doutorado / Pesquisa Experimental / Doutor em Cirurgia

No description available.

Resumo: Experimento 1: Foram avaliados os efeitos da substituição do milho pelo sorgo na ração para frangos de corte sobre o desempenho, o rendimento de carcaça e partes, a morfometria (densidade de vilos, altura dos vilos, profundidade das criptas, número de células caliciformes e índice mitótico nas criptas) e a integridade da mucosa do duodeno, jejuno e íleo, e a atividade das enzimas de membrana (aminopeptidase, fosfatase alcalina e maltase) da mucosa do jejuno. Foram utilizados 792 pintainhos de um dia machos, Cobb-500, distribuídos ao acaso em quatro tratamentos (0, 50, 75 ou 100% de substituição do milho pelo sorgo do 1º ao 42º dia) e seis repetições. No 7º, 21º e 42º dia o peso dos frangos e as sobras das rações foram aferidas, e foram obtidas amostras do intestino delgado de um frango por repetição. Experimento 2: Foi avaliado o efeito da substituição total do milho pelo sorgo sobre as Enterobactérias, Lactobacillus spp, Clostridium perfringens (Log10 UFC/g), a viscosidade e o pH do conteúdo ileal. Cem pintainhos foram distribuídos em dois grupos e alimentados com rações à base de milho ou sorgo do 1º ao 42º dia de idade. Concluiu-se desses experimentos que a substituição do milho da ração por sorgo, na fase inicial (1 a 21 dias), não altera o desempenho e a função da mucosa do intestino delgado dos frangos. A substituição parcial do milho pelo sorgo (50 ou 75%) durante a fase total de criação (1 a 42 dias) melhora a conversão alimentar dos frangos. A substituição total (100%), até os 42 dias, prejudica a estrutura dos vilos do duodeno e jejuno, mas, diminui a colonização por Clostridium perfringens no íleo e a viscosidade do conteúdo ileal. A substituição de 75 ou 100% até os 42 dias diminui a atividade de aminopeptidase e maltase. O rendimento de carcaça e partes, a atividade da fosfatase alcalina intestinal e as populações ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Experiment 1: The effects of substitution of corn by sorghum in diets for broiler chickens on performance, carcass and parts (breast and thigh+drumstick), morphology (density of villi, villous height, depth crypts, number of goblet cells and mitotic index in the crypts) and integrity (score of epithelial loss) of the duodenum, jejunum and ileum mucosa, and the activity of membrane enzymes (aminopeptidase, intestinal alkaline phosphatase, and maltase) of the jejunum. We used 792 day-old chicks male Cobb-500, were randomly assigned to four treatments (0, 50, 75 or 100% replacement of corn by sorghum 1 to 42 days) and six replications. At 7, 21 and 42 days the weight of the chickens and the remains of the diets were measured, and samples were collected from the small intestine of a chicken for replication. Experiment 2: The effect of total substitution of corn by sorghum on the counts of Enterobacteriaceae, Lactobacillus spp and Clostridium perfringens, viscosity and pH of ileal contents. One hundred chicks were divided into two groups and fed diets based on corn or sorghum, 1 to 42 days of age. From the results of these experiments it was concluded that the substitution of corn by sorghum in the initial phase (1 to 21 days) does not affect the performance and function of small intestinal mucosa of chickens. The partial substitution of corn by sorghum (50 or 75%) during the total period (1 to 42 days) seems to improve feed conversion of chickens. Total substitution (100%), up to 42 days, affect the structure of the villi of the duodenum and jejunum, but reduced colonization by Clostridium perfringens in the ileum and the viscosity of ileal contents. The replacement of 75 or 100% up to 42 days reduces the activity of aminopeptidase and maltase. The carcass and parts, the activity of intestinal alkaline phosphatase and the count of Enterobacteriaceae and Lactobacillus spp, are not affected by treatments / Orientador: Marcos Macari / Coorientador: Renato Luis Furlan / Banca: Alex Maiorka / Banca: Alice Eiko Murakami / Banca: Isabel Cristina Boleli / Banca: João Martins Pizauro Junior / Doutor

Background: Recent national trends and distribution of ileal pouch-anal anastomosis (IPAA) procedures for patients with ulcerative colitis (UC) are unknown. We examined the frequency of use of elective IPAA procedures among patients with UC and the distribution of IPAA procedures across more than 140 U.S. academic medical centers and their affiliates. Methods: Data were obtained from the University HealthSystem Consortium for patients with a primary diagnosis of UC admitted electively between 2012 and 2015. Results: The mean age of the study population (n=6,875) was 43 years and 57% were men. Among these, one-third (n=2,307) underwent an IPAA, while two-thirds (n=4,568) underwent colectomy, proctectomy, proctocolectomy or other procedures. The proportion of IPAA cases among all elective admissions was relatively stable at 33-35% during the years under study. A total of 131 hospitals, out of 279 hospitals participating in the UHC, performed IPAA. The median number of IPAA cases performed annually was 1.9 [IQR 0.8 – 4.3]. Nearly one half (48%) of these cases were performed by the top ten hospitals. Overall, only a total of 30 centers performed ³ five elective IPAA cases annually. Conclusions: Although the frequency of elective IPAA surgery in recent years has been stable, nearly one half of all IPAA cases was performed at ten hospitals. The concentration of IPAA cases at high-volume centers, and the steady number of cases performed annually, have potential implications for fellowship training, patient clinical outcomes and access to care.

The objectives of the research were to examine the effects of high dietary levels of fibrous feeds, and of supplementation with Roxazyme® G2 (RX), on the digestive metabolic and physiological responses of growing pigs fed maize-soybean diets. The nutrient and dietary fibre (DF) composition, the swelling and water-binding capacities of maize (MM), its hominy chop (HC) and cobs (MC), dehulled soybean (dSBM) and the hulls (SH), brewer’s grains (BG), lucerne hay (LH) and wheat bran (WB) were evaluated using standard procedures. Feed fibre fractions were isolated by simulating upper tract digestion in an Ankom® DaisyII Incubator, whereby each feed was digested in pepsin (porcine, 200 FIP-U/g, Merck No, 7190), followed by pancreatin (porcine, grade IV, Sigma No P-1750), with recovery of the fibrous residues. In a third step to complete the simulated pig gastro-intestinal digestion, the pepsin-pancreatin fibre extracts were digested by RX or Viscozyme L ® V2010 (VZ). Enzyme activity was measured as the coefficients of partial degradability (solubilisation) of the washed fibre extracts. The kinetics and products of fermentation of the DF were evaluated in an AnkomRF gas production system, using buffered faecal inoculum. Among the feed ingredients, dissimilar, fibre source-dependent activities between RX (0.02 to 0.12) and VZ (0.04-0.33) were observed. The lowest RX activities were observed on the maize and soybean derived fibres, with similarly low VZ activity on MC fibre. Variation in the activity of faecal microbial enzymes was similarly indicated by the variable production of fermentation gas (51.8-299.4 mL g-1 DM) and short chain fatty acids (SCFA) (2.3-6.0 mMol g-1 DM). Soy hull, dSBH, MM and HC fibres were highly fermentable, with low fermentability of BG, MC and WB fibres. The fibres differed in the composition of fermentation SCFA, whereby SH, LH and MC shifted fermentation to Ace, and BG, dSBM, WB, MM, HC favoured Pro, while MM and HC favoured But production. The same nutritional properties were similarly evaluated in complete diets which were formulated from the ingredients for growth, and metabolic trials. For the growth trial, a standard (STD) (control), 141 g total dietary fibre (TDF) kg-1 dry matter (DM) maize-soybean growing pig diet, and five iso-nutritive, 246 g TDF kg-1 DM nutritionally balanced diets were formulated. The high DF was achieved by partial replacement of the MM and dSBM in the STD diet with MC, SH, BG, LH or WB. The differences in RX and VZ activities and in the fermentation characteristics which were observed on the fibre extracts from the high fibre ingredients were reflected in the DF from the respective complete diets in which they were included. However, the fibre from the basal dietary ingredients reduced the absolute values and the variation in the activities of RX (0.03-0.06) and VZ (0.16-0.22), and similarly reduced the variation in gas (126.6-187.6 mL g-1 DM) and SCFA (4.1-5.4 mMol g-1 DM) production of the DF from the fibrous diets. Enzyme activities on the STD DF were low for RX (0.03) and high for VZ (0.25). The STD DF produced 205.3 mL gas g-1 DM, which was similar to SH DF, and higher than all the other diets. The STD DF produced 5.0-mMol SCFA g-1 DM, which was quantitatively, and not statistically higher than the other fibres. The composition of SCFA was similar across all diets, except for the high percent Ace, with low Pro by the SH DF. Compared to the STD, the high DF diets increased percent Ace, with reduced Pro and But. The STD, MC, SH, BG, LH and WB diets were each prepared in duplicate mixes, one of which was fortified with 200 mg RX kg-1 feed (as fed). Seventy-two intact Large White X Landrace, male, 32.0 ± 5.6 kg live weight (LW) pigs were allocated to the diets in two completely randomised weight blocks in a 2 (fibre source) X 2 (enzyme) factorial arrangement. The pigs were fed ad libitum for 10 weeks. Cumulative LW gain and feed intake were measured at different stages of growth, and at slaughter. Apparent total tract digestibility (ATTD) of nutrients was estimated at 65-70 kg LW, using 0.2% (as fed) chromium oxide as the indigestible marker. Ileal tissue was sampled 50 cm above the ileo-caecal valve, on which villi height and area, and crypt depth were evaluated by computerised image analysis. Blood was sampled at slaughter from the severed vena jugularis, 16 hours after feeding. Serum urea, creatinine, triglycerides, glucose, and total cholesterol were analysed chemically. The serum metabolome was further explored using Proton Nuclear Magnetic Resonance Spectroscopy (1H -NMRS). There was fibre X RX interaction for villi height, whereby the enzyme reduced the villi height in pigs on the SH, STD and WB diets, with an opposite effect on pigs on the MC, BG, LH diets. The soluble fibre content was negatively correlated with crypt depth. Chemical analysis did not detect differences in metabolite concentration between the STD and the high fibre diets. However, more serum cholesterol was observed in pigs fed the WB compared to the LH and MC diets. 1H-NMRS indicated that feeding pigs the WB diet increased serum Cys and His, while supplementation of RX increased serum formate, glucose, and urea. There was diet X enzyme interaction for fructose, glucose, Arg, Cys, Ser, and Trp, whereby RX increased the levels in pigs on MC and WB, with an opposite effect in pigs on the other diets. There was large DF source-dependent variation among diets in ATTD of DM (0.80-0.85), organic matter (OM) (0.81-0.87), gross energy (GE) (079-0.85) and CP (0.81-0.85), whereby, relative to the STD diet, high DF reduced the ATTD of DM (all diets except SH), organic matter (OM) and energy and CP (all diets except the MC). Positive correlation was observed between fermentability and the ATTD digestibility of DM, OM, energy, ADF, NDF, and fat. Negative correlation was observed between the swelling capacity and the ATTD of DM, OM, energy and protein, between DF solubility and DM, OM, protein, ADF and NDF, and between water binding capacity and ATTD of DM and OM, energy and NDF. At slaughter, there was similarly large, and DF source-dependent variation among the high fibre diets in feed intake (2.31-2.71 kg as fed day-1), live weight gain (0.75-0.86 kg day-1), and feed: gain ratio (2.73-3.00). Corresponding values for the STD diet were 2.44 kg day-1, 0.83 kg day-1and 2.86 kg day-1, respectively. Relative to the STD, LH reduced feed intake and live weight gain, and MC increased the feed: gain ratio. Predictions based on the in vitro fermentability of DF and feed intake suggested that due to poor fermentability, and or restriction of feed intake, relative to a standard fibre diet, high dietary levels of MC, WB and BG may reduce fermentation in the lower gut, while similar dietary levels of SH and LH may result in substantial increases in fermentation. At 50 kg LW, the fermentability of DF was positively correlated with feed intake and with weight gain, while water binding capacity and solubility of DF were negatively correlated with feed intake. At slaughter, the solubility of DF was negatively correlated with feed intake and feed: gain ratio. Large variation among the high fibre diets was also observed in the slaughter weight (89.2-96.8 kg), dressing % (68.6-76.4), meat colour (80.4-82.3), lean % (69.5-71.2), and fat % (10.1-12.6). In comparison, pigs on the STD diet scored 94.7 kg slaughter weight, 75.1% dressing, 81.6 cm carcass length, 82.5 meat colour, 68.4% lean, and 15.0% fat. Relative to the STD, LH reduced dressing and fat %. Lucerne hay and WB increased the lean%. For the metabolic trial, two iso-nutritive, mixed high fibre (319 g TDF kg-1 DM), nutritionally balanced diets were formulated to contain DF of high (HF) versus low (LF) fermentability. The diets had similar content of soluble DF and similar swelling and water binding capacities. Viscozyme was more active than RX on both the HF (0.20 versus 0.04) and the LF (0.17 versus 0.07) DF. The combination of RX and VZ statistically increased the enzyme activity on the HF (0.25) and quantitatively increased enzyme activity on the LF (0.18) DF, suggesting additive or synergistic effects. More gas was produced by the HF (159.5 mL g-1 DM) compared to the LF DF (96.6 mL g-1 DM). More SCFA were produced by HF (5.0 mMol g-1 DM), compared to the LF DF (3.6 mMol g-1 DM). Compared to the STD, HF DF increased percent Ace, with reduced Pro and But. The LF DF increased percent Ace, with quantitative, and not statistical reduction of Pro and But. In a metabolic trial, the HF and LF diets, and their duplicates containing 0.270 g RX kg-1 DM of feed (as fed) were fed ad libitum to eight ileum T-cannulised, intact Large White X Landrace male pigs weighing 65.0 ± 5.1 kg. The diets were allocated to the pigs in a duplicate 4 x 4 Latin Square design, in a 2 (enzyme) x 2 (fermentability) factorial arrangement. Each period consisted of two weeks of adaptation followed by five days of sampling. The ileal digesta was collected in each period and was similarly subjected to the fermentation test. Apparent ileal digestibility (AID) and ATTD were determined using 0.2% (as fed) chromium oxide as the indigestible marker. N excretion in faeces and urine were measured, and N retention was calculated. Blood was sampled by vena jugularis puncture on the last day of each period. Two blood samples were collected, the first 15 hours after removal from feed (15-hour serum), and the second 3 hours after re-introduction to feed (3-hour serum). Serum metabolites were evaluated by both chemical analyses and by 1H-NMRS, as described for the growth trial. Roxazyme did not affect the fermentation characteristics of the ileal digesta. In similar proportion to the fermentability of the PP digesta, the HF ileal digesta was more fermentable (65.4 mL gas g-1 DM and 6.1 mMol SCFA g-1 DM) than the LF ileal digesta (46.7 mL gas g-1 DM and 4.4 mMol SCFA g-1 DM SCFA). Prediction based on the in vitro fermentability of DF and feed intake suggested the HF diet could support one half times more fermentation in the lower gut compared to the LF diet. The HF diet had higher AID of DM (62.5 vs. 58.6), OM (65.6 vs. 62.1), energy (64.4 vs. 61.0), fat (85.8 vs. 81.7) and ash (41.8 vs. 32.7). The AID of HO-Pro, Met and Val were higher for the LF diet. There was diet X enzyme interaction on the AID of Met, whereby the RX reduced the AID of met in the LF diet, and not that of the HF diet. The ATTD was higher for the HF diet for DM (74.2 vs. 68.4), NDF (64.7 vs. 57.4), and ADF (35.1 vs. 21.0). There was positive correlation between the fermentability of DF and the AID DM, OM, ash, ash, fat and energy. The solubility of DF was negatively correlated with the AID of DM, OM, ash, fat, ADF and energy, and with the ATTD of DM, OM, ash, fat, energy, NDF, and ADF. Negative correlation was also observed between the swelling capacity of DF and the AID of protein, Trp and Lys. The solubility of DF was positively correlated with Ser, Ala, Val, Iso-Leu and His. There was diet X enzyme interaction for urea in the 15- hour serum, whereby RX tended to reduce the urea in the LF diet, while it increased that of the HF diet. Fermentability negatively correlated with urea in the 15- hour serum, and positively correlated with serum glucose in the 3-hour serum. In the 3-hour sample, 1H-NMRS indicated higher fucose, Pro and cholesterol in the LF diet. 1H-NMRS also indicated fermentability x RX interaction for Ser, Tyr, Lys, creatine, and possibly, glucose or fructose, glycerol or Gly and His or Arg, whereby RX increased the levels in the LF diets, with opposite effect in the HF diet. In conclusion, enzyme activities and fermentability were higly variable among different DF sources, and the effects were evident in the fibrous complete diets. The results of the in vitro studies supported the application of the methods to formulate fermentable insoluble fibre-rich, maize-soybean-mixed co-product diets. Correlation analyses suggested that DF fermentability, and solubility, swelling and water binding capacities explained significant proportions of the variances of the metabolic and physiological responses of the pigs to different feeds. Predictions based on the in vitro fermentability of DF and feed intake suggested that a strategy whereby pig diets are enriched in DF after the feedstuffs are screened on DF fermentability could substantially increase fermentation in the lower gut. Overall, the results suggested that productivity can be maintained in growing pigs fed diets containing up to twice the standard levels of DF, provided producers target co-product feeds that contain highly fermentable DF. The use of RX to improve nutrient digestion and to stimulate gut fermentation was not justified. / Environmental Sciences / Ph.D. (Environmental Sciences)

Les Escherichia coli entérohémorragiques (EHEC) sont des pathogènes majeurs pour l’homme responsables de toxi-infections alimentaires pouvant évoluer vers des complications potentiellement mortelles. La pathogénicité de ces souches est essentiellement due à la production de Shiga-toxines (Stx), même si d’autres facteurs semblent jouer un rôle important dans la virulence, comme des facteurs d’adhésion. La survie et la régulation des facteurs de virulence des EHEC dans l’environnement digestif humain sont des facteurs clés dans la pathogénicité bactérienne, mais restent à ce jour mal décrits, essentiellement en raison d’un manque de modèles d’étude adaptés. De plus, l’absence de traitement spécifique a conduit à s’intéresser à des moyens préventifs et/ou curatifs alternatifs, comme l’utilisation de probiotiques. L’objectif de ce travail de thèse est (i) de mieux comprendre le comportement de la souche de référence EHEC O157:H7 EDL933 dans l’environnement digestif humain simulé, et en particulier ses interactions avec le microbiote résident et l’épithélium intestinal, et (ii) d’évaluer l’effet antagoniste d’une souche de levure probiotique vis-à-vis de la survie, la virulence et l’interaction du pathogène avec l’épithélium intestinal, à l’aide d’approches in vitro et in vivo complémentaires. En modèles digestifs in vitro, la souche EHEC survit dans l’estomac, voire se multiplie dans les parties distales de l’intestin grêle, alors qu’elle ne se maintient pas dans l’environnement colique. Les gènes de virulence codant les Stx et des adhésines majeurs (intimine et « Long Polar Fimbriae » ou Lpf) sont surexprimés dès les parties hautes du tractus digestifs, et ce, même en absence de cellules épithéliales. Les conditions rencontrées dans le tractus digestif supérieur de l’enfant, comparativement à celui de l’adulte, conduisent à une survie et un niveau d’expression des gènes codant les Stx et les Lpf plus élevés chez l’enfant, ce qui peut contribuer à expliquer la grande sensibilité de cette population aux infections à EHEC. Enfin, les Lpf semblent jouent un rôle clé dans le ciblage spécifique des cellules M et le tropisme des EHEC pour les plaques de Peyer, et ce, à la fois in vitro (cellules M en culture) et in vivo (anses iléales murines). Même si elle ne modifie pas la survie du pathogène dans l’environnement colique, la levure probiotique S. cerevisiae CNCM I-3856 a montré des propriétés antagonistes intéressantes vis-à-vis d’EHEC O157:H7 en (i) modulant favorablement l’activité fermentaire du microbiote intestinal, (ii) diminuant significativement l’expression des gènes codant les Stx et (iii) inhibant la translocation bactérienne au travers des plaques de Peyer et les lésions hémorragiques associées. Par ailleurs, l’effet du pathogène et des probiotiques sur le microbiote colique est individu dépendant, confortant l’hypothèse que des facteurs associés à l’hôte, comme le microbiote, pourraient conditionner l’évolution clinique des infections à EHEC et l’efficacité d’une stratégie probiotique.Ce travail de thèse contribue à une meilleure compréhension du comportement des EHEC dans l’environnement digestif humain et confirme l’intérêt d’une stratégie probiotique dans la lutte contre le pathogène. Une étude plus approfondie du transcriptome du pathogène dans l’environnement digestif et une analyse par des méthodes haut débit du microbiote intestinal permettraient de continuer à mieux décrire la physiopathologie des infections à EHEC et comprendre les mécanismes associés à l’effet antagoniste des probiotiques. / The enterohemorrhagic Escherichia coli (EHEC) are major zoonotic pathogens responsible for food-borne infectionwhich leads to life-threatening complications in humans. The main virulence determinant of EHEC is the production of Shigatoxins (Stx), even if other factors seem to play an important role in virulence, such as adhesion factors. Survival and virulenceof EHEC strains in the human digestive environment are a key factor in bacterial pathogenesis but remains unclear owing tolack of relevant model. Moreover, no specific treatment has led to interest in preventative and / or curative alternatives, suchas using probiotics. The objective of this study is to better understand the behavior of the reference strain EHEC O157:H7EDL933 in the entire digestive tract, and in particular its interaction with the resident microbiota and the intestinal epithelium,and to evaluate the antagonistic effect of the probiotic yeast, Saccharomyces cerevisiae CNCM I-3856, using in vitro and in vivo complementary approaches.In vitro, bacterial mortality was noticed in the stomach, whereas bacterial growth resumption was observed in thedistal parts of the small intestine and the pathogen was not able to maintain in the human colonic conditions. Virulence genesencoding Stx and adhesins (intimin and “Long polar fimbriae”) are upregulated in the upper parts of the digestive tract. A ten-time higher amount of cells was found in the ileal effluents of infant compared to adult. stx genes were over-expressed (up to25-fold) in infant conditions compared to the adult ones. This results show that differences in digestive physicochemicalparameters of the upper gastrointestinal tract may partially explain why infants are more susceptible to EHEC infection thanadults. And finally, Lpf seem to play a key role in the interactions of EHEC with murine Peyer’s patches and are needed for anactive translocation of the pathogen across M cells, and both in vitro (M cells culture) and in vivo (murine ileal loops).S. cerevisiae had not effect on EHEC survival in the colonic environment but (i) favorably influenced gut microbiotaactivity through beneficial modulation of short chain fatty acid production, (ii) leading to significantly decrease stx expressionand (iii) significantly reduced EHEC translocation through M cells and inhibited in vivo interactions of the pathogen withPeyer’s patches and the associated hemorrhagic lesions. Probiotic had donor-dependent effect on the gut microbiota strengthenthe hypothesis that host-associated factors such as microbiota could influence the clinical evolution of EHEC infection and theeffectiveness of a probiotic strategy.This work contributes to a better understanding of the behavior of EHEC in the human digestive environment andconfirms the interest of probiotic strategy in controlling EHEC infections. Further transcriptome studies are warranted for thepathogen in the human digestive environment, with or without probiotics for the better understanding of the pathophysiologyof EHEC and so on the mechanisms involved in the antagonistic effect of probiotics.