Dissertations / Theses on the topic 'Digestion – Teneur en acides aminés'
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Benhaddou, Soukaïna. "Étude de la biodisponibilité digestive et métabolique des protéines alimentaires après bypass gastrique." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASB005.
Bariatric surgery stands as the most effective treatment for morbid obesity, with the Roux-en-Y Gastric Bypass (RYGB) being a commonly employed procedure. Its efficacy in weight loss and the reduction of comorbidities has been extensively demonstrated. Despite its frequent association with protein deficiency, the consequences of RYGB on the digestive and metabolic availability of proteins remain poorly understood. This thesis aims to assess the effects of RYGB on the digestive and metabolic fate of dietary proteins, using a test meal containing ¹⁵N labeled milk proteins in both rats and humans. Rats were monitored for 1 or 3 months post-RYGB to evaluate its mid-term effects on the intestinal mucosa, digestibility, and metabolic availability of dietary proteins. This study showed that protein digestibility was not altered by RYGB, even though the intestinal mucosa is hypertrophied. A transient decrease in nitrogen retention in peripheral organs and a persistent increase in deamination of dietary amino acids (AA) were observed. In humans, the metabolic fate of proteins was assessed one month before and six months after RYGB in 4 patients over 9 included (NCT04934826). Three of them exhibit a mild to marked increase in AA catabolism. RYGB induced variable modifications in dietary nitrogen metabolism among individuals. This thesis demonstrated that RYGB alters the metabolic availability of proteins, mainly through an increase in postprandial catabolism of AA. In addition to these studies, the development of small intestinal organoids of rats was conducted to mimic intestinal modifications after RYGB. The organoids exhibit substantial variability (size, shape, and gene expression), with no differences observed between those derived from control rats and RYGB rats
Lamghari, El Kossori Lalla Radia. "Effets des concentrés protéiques de Lupin blanc doux (Lupinus albus) sur la prise alimentaire." Nancy 1, 1996. http://www.theses.fr/1996NAN10345.
Cozannet, Pierre. "Valeur nutritionnelle des drêches de blé liées à la production de bioéthanol pour les animaux monograstriques." Rennes, Agrocampus Ouest, 2010. http://www.theses.fr/2010NSARB208.
Two European Directives have set indicative targets to promote the use of renewable fuels in the transport sector. This terminology includes tswo main productions, bioethanol and biodiesel. The biodiesel comes from crute fat esterification. Bioethanol is currently produced via fermentation of glucose into ethanol. When this productin is realized from cerals, mainly wheat in Europe, it results in one main by-product, the dredi distillers grains with solubles (DDGS) whose nutritional value is poortly described, especially for non ruminants. Thus, the purpose of the thesis has been to measure average nutrients content energy values for pigs (growing pig, adult sow) and poultries (adult rooster, broiler, latyer, growing turkey) and the protein values (standardized ileal digestibility ; SID) for pigs and poultries of 10 European what DDGS samples selected to be representative of all the existing situations
Managau, Lyliane Marie. "Contribution à l'étude de la matière organique estuarienne et marine : classe des acides aminés." Brest, 1987. http://www.theses.fr/1987BRES2012.
Miele, Alberto. "Recherches sur la composition en acides aminés et en acides gras des feuilles et des raisins de Vitis vinifera L. Cv Cabernet Sauvignon pendant la période de maturation et en fonction du système de conduite." Bordeaux 2, 1986. http://www.theses.fr/1986BOR20023.
Barbé, Florence. "Compréhension et modélisation de l’impact de la structure des matrices laitières sur la biodisponibilité des acides aminés chez le mini-porc." Rennes, Agrocampus Ouest, 2012. http://www.theses.fr/2012NSARB229.
The impact of the structure on the biological and nutritional properties of food has received a growing interest recently. Digestion is a complex process involving different steps such as the macronutrients hydrolysis, their gastric emptying and subsequent transit in the small intestine, the release of their hydrolysis products, and the absorption of the final nutrients. All of these mechanisms are susceptible to be influenced by the structure of the meal. Milk is a widely consumed product in human nutrition and milk proteins are well-known for their ability to provide essentials amino acids to the body. Milk can be transformed into a high diversity of manufactured derivatives, such as yogurt and cheese. Moreover these foods are highly digestible and also known as sources of potential bioactive peptides and amino acids having physiological roles. For these reasons, milk could be considered as a potent vector of nutritional benefits. This study aimed at investigating the effect of the dairy matrix structure, as modified by processes commonly used in the dairy industry, on the digestion kinetics of the milk proteins, caseins and β-lactoglobulin. Three processing operations have been investigated alone or in combination: heat treatment and either acid- or rennet-induced gelation of milk. A total of six dairy matrices having the same composition, but differing by their structures, were prepared: unheated and heated skim milk, the corresponding rennet gels, and a non-stirred or a stirred acid gel prepared from the heated milk. These meals were then given to six minipigs fitted with cannulas at the duodenum and mid-jejunum and an arterial catheter. Effluents and plasma samples were collected at different times over a 7 h-period after meal ingestion. Duodenal chromium concentrations (marker of the liquid phase of the meal), dry matter content, residual concentrations of milk proteins, production of peptides and plasmatic amino acid concentrations were followed over the postprandial period. Caseins and β-lactoglobulin were respectively sensitive and resistant to hydrolysis in the stomach with the unheated matrices, but showed similar digestion kinetics with the heated matrices. Rennet- and acid-induced gelation of milk slowed down the outflow of the meal from the stomach and delayed the duodenal appearance of both proteins and the subsequent absorption of amino acids, which resulted in a decrease in their bioavailability in peripheral blood. The rennet gels, and more specifically the raw rennet gel, displayed specific digestion behaviour with low levels of all the parameters measured in the duodenal effluents and in the plasma. Several hypotheses were proposed to explain the rennet gels specific digestion, such as a dilution by digestive secretions, a resistance to hydrolysis and a long gastric retention due to a mechanism of gastric syneresis. The overall digestion of both proteins was high at the jejunal site, whatever the structure of the ingested dairy matrix was. The gastric phase was thus shown to play a key role in the control of nutrients delivery and bioavailability, milk protein absorption being conditioned by their rate of appearance in the duodenum. When focusing on the population of peptides released in the duodenum, the structure of the dairy matrices did not affect the location of cleavage sites, but had an impact on the number of peptides identified. As a complementary method to animal experiments, an in silico approach was used to have a mechanistic understanding of the digestion process. A compartmental model, based on ordinary differential equations, was developed to match closely in vivo measurements by describing the gastric emptying, intestinal transit and the subsequent absorption of exogenous amino acids. This model provided a good fitting of experimental data and allowed estimating parameters, mainly related to the transit along the digestive tract. Model simulations showed that differences in the kinetics of amino acid absorption can be fully understood by considering the behaviour of the dairy matrices within the stomach. This model offers interesting perspective for the integration of food structure parameters, and more particularly for dairy products, in the comprehensive view of the nutritional quality of food products. The in vivo and in silico approaches employed in this study therefore underlined the crucial influence of the product structure on nutrient bioavailability. They also added valuable contribution to consider the manufacturing of food as a promising tool for specific nutrition goals adapted to different subpopulations (elderly, overweight people…)
Amiche, Mohamed. "Les Peptides opioïdes de la peau d'amphibiens : la dermophine et la dermenkephaline : études structurales et pharmacologique." Paris 6, 1990. http://www.theses.fr/1990PA066017.
Dandach, Said. "Rôle des acides aminés dans la production d'amines biogènes chez Oenococcus oeni." Thesis, Dijon, 2013. http://www.theses.fr/2013DIJOS020/document.
In wine biogenic amines (BA) are mainly of microbial origin, Oenococcus oeni, the mainresponsible for malolactic fermentation, has been identified as a BA producer from nitrogenprecursors. Oenococcus oeni possess numerous amino acid auxotrophies that are precursors ofbiogenic amines. No study has been done so far to look at the relationship betweenauxotrophy for amino acids precursors of BA and the level of BA in the medium. In order todo so, 80 Oenococcus oeni strains were isolated from red wines. The detection of genesencoding the different decarboxylases responsible for BA synthesis has been realised. Inparallel, the auxotrophy for the four amino acids (Arg, Tyr, His, Phe) precursors of BA hascharacterized. Our results demonstrate that there is not direct correlation between auxotrophyand the accumulation of the corresponding BA as well as between the presence ofdecarboxylase gene and the accumulation of the corresponding BA. High levels of agmatineproduced from arginine decarboxylation by Oenococcus oeni is reported for the first time.Agmatine production is strain dependant. the most adapted to acidic environment is the strainwhith use arginine in higher level with same proportion for ADI pathway and argininedecarboxylase. Agmatine addition in wines reduce woody aroma probably by formation ofsciff bases between aromla compounds and amine
Zouaoui, Maroua. "Étude de l'impact des enzymes exogènes sur la digestibilité des acides aminés chez le porc et le poulet : approche par méta-analyse." Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/33069.
Phytates and non-starch polysaccharides (NSP) are abundant antinutritional factors in pig and broiler diets. Although phytates constitute a phosphorus (P) reservoir, this P is not available because monogastric animals produce a small amount of endogenous phytase. Microbial phytases have been incorporated into diets and has revealed the negative effect of phytates on the digestibility of amino acids (AA). In addition to phytates, NSPs are also indigestible and resistant to the digestion process in monogastric animals. The NSPs encapsulate also nutrients, which decrease AA and energy digestibility. It is important to know the mechanisms of action of phytase and xylanase in the degradation of antinutritional factors and improving the digestibility of AA, as well as apparent metabolizable energy content (AME). A meta-analysis approach allowed to establish models for predicting the digestibility of AA from dietary AA, phytase and NDF (Neutral Detergent Fiber) concentrations in pigs, and from dietary AA, phytase and phytic phosphorus (PP) concentrations in broilers. A predictive model of AA digestibility in broilers has also been established from xylanase supplementation and dietary NDF/NSP concentrations. Finally, xylanase activity, gross dietary energy (GE) and NDF/NSP concentrations were the best predictors of AME. The current models allow quantifying the effect of phytase on AA in pigs and broilers and the effect of xylanase on AA and AME in broilers, which is important to use these enzymes accurately in diet formulation.
Idrissi, Taghki Abdelghani. "Etude du type métabolisme intégré entre embryons de colza natif et transgénique : analyse et compréhension de la modification induites dans les lignées transgéniques de colza et de lin : analyse enzymatique et métabolique." Compiègne, 2009. http://www.theses.fr/2009COMP1798.
The importance of these unusual structures for fatty acids, the development of genetic engineering and the identification and isolation of many genes involved in the biosynthesis and regulation of lipid metabolism in plants, have provided new perspectives for the production of vegetable oil with a higher value in field crops. In this perspective, REFLAX and PAGIOS programmes were developed. The aim of these projects is the production of unusual fatty acids in agronomie plants (rapeseed and flan), through the creation of a new ,biosthetic pathway for branched fatty acids in the plast. Rapeseed plants were transformed with four bacterial enzymes: TD, KS, PCCA and PCCB. These proteins were identified as key enzymes in the synthesis of branched fatty acids. The level of methylmalonyl-CoA, a precursor of the methyl branched fatty acid synthesis, was amplified thanks to the introduction of these four genes. However the accumulation of methyl branched-chain fatty acids in rapeseed plants transformed, remains very low (<2%). To get a deeper understanding of this low production of BFA, we incubated whole rapeseed embryos, at different stages of development, in presence of 13C-labelled glucose and observed the label redistribution by NMR. The NMR and biochemical analysis showed that the synthesis of BFA was very low and transient (only at 15 J). Biomass synthesis fluxes were similar between native and transformed plant. The central carbon metabolism was not affected by the introduction of these genes. However, an accumulation of' pyruvate and kétobutyrate and a low accumulation of branched Chain amino acids (leucine, isoleucine and valine) at the transformed lines were observed
Silvestre, Marialice Pinto Coelho. "Nouvelles méthodes d'étude de la composition d'hydrolysats de caséine (cuprimétrie, spectrophotométrie, chromatographie d'exclusion stérique) : application à l'estimation de leur teneur en di- et tripeptides." Paris 11, 1993. http://www.theses.fr/1993PA114820.
Barbier, Hugues. "Recherche de marqueurs associés à la contrainte en azote et en carbone chez la vigne (vitis vinifera var. Cabernet Sauvignon)." Bordeaux 2, 2004. http://www.theses.fr/2004BOR21095.
The stake of the vine growing, is to produce fruits of quality suitable for the manufacture of wine. For that, the growing methods related to the control of the nitrogen contribution (nitrate fertilizers and the availability of carbon (limitation of leaf aera). This thesis work concerned the search for biochemical and molecular markers on grape (Vitis vinifera var Cabernet Sauvignon) associated with nitrogen and carbon constraints. He biochemical (sugar concentration, free amino acids, and ecophysiologic (growth of the vegetative parts) studies of fruit-bearing cuttings showed that the growth (size if the plants and leaf aera) is the more discriminating character between the plants under constraint and control conditions. But they did not allow to disciminate the nitrogen and the carbon constraint. A molecular study was thus undertaken by realization of SSH libraries (Subtractive Suppressive Hybridization) for the plants placed in nitrogenized constraint vs control plants. The screening of these libraries by microarrays highlighted 137 clones induced or repressed by the nitrogen constraint
Jreij, Rana. "Incidence des itinéraires culturaux : fertilisation foliaire azotée, irrigation et hauteur de haie végétale, sur la composition azotée des baies de Vitis vinifera en climat méditerranéen." Montpellier 1, 2008. http://www.theses.fr/2008MON13517.
Le, Floc'h Nathalie. "Régulation nutritionnelle de l'oxydation de la thréonine chez le porc." Aix-Marseille 3, 1995. http://www.theses.fr/1996AIX30028.
Bierla, Katarzyna. "Approches analytiques pour la quantification par spectrométrie de masse élémentaire et moléculaire du sélénium total, des acides aminés et métabolites séléniés dans les matériaux biologiques." Pau, 2008. http://www.theses.fr/2008PAUU3003.
The thesis presents methodological developments and solutions to several problems concerning the analysis of biological samples for the concentration of the total selenium and its species. As a contribution to the methodology for the total Se determination, the use of Xe as a non-reactive collision gas was proposed to eliminate the polyatomic interferences in Se detection by ICP MS. This allowed anaccurate determination of Se isotope ratios without mathematical correction. The principal part of the thesis concerns the development of methods for the quantitative determination of the Se-aminoacids (selenomethionine (SeMet), selenocysteine (Secys)) in animal blood, soft tissues and milk. The methods developed are based on the quantitative carbamidomethylation of SeCys and SeMet followed by their proteolytic release from proteins. The fraction isolated by size-exclusion chromatography was submitted to ion-paring HPLC - ICP MS analysis. In terms of contribution to speciation analysis of Se-rich plants, the work proposes a sequential extraction scheme allowing the recovery of Se from garlic. Se in Se-enriched garlic was fractionated by a sequential procedure including leaching with water, lysis, proteolysis, leaching with HCI, sulfite and CS and, finally, digestion of the residue. A strategy for the standardless identification of unknown water-soluble low-molecular weight Se metabolites by molecular mass spectrometry is pursued for monkeypot nuts. The use of size-exclusion, cation-exchange and ion-paring reversed-phase HPLC allowed the purification of selenocystathionine and its y-glutamyl-derivatives to a degree allowing their formal identification by organic mass spectrometry
Salgado, Romero Héctor Hernando. "Estimation of apparent ileal digestibility of amino acids in ingredients used in broiler diets and basal endogenous losses through meta-analysis approach." Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27738.
The use of digestible amino acid system is certainly superior to total amino acids (tAA) in feed formulation, if the objective is optimizing protein use by birds. With considerable information reporting AA digestible values of ingredients used in broiler diets, the objective of this study was to predict amino acid (AA) digestibility based on proximal analysis of ingredient using a meta-analysis approach. Two models were performed: 1) Y = apparent digestible AA (AAdig, % diet); X = dietary CP (%) and 2) Y = AAdig (g/kg of DM); X = total analyzed AA (tAA, g/kg of DM) in which the intercept is the endogenous losses (EL). A database of 49 publications was divided in 5 sub-databases: 1) cereals (barley, sorghum, wheat and corn), 2) soybean meal (SBM), 3) meat and bone meal (MBM), 4) database 1 plus faba beans and peas to study El and 5) only peas and faba beans. The study and ingredient were included as fixed effects. In cereals, prediction of AAdig by CP was accurate (R² from 0.68 for Thr to 0.92 for Ala). The slope was different between cereals (cereal x CP; P < 0.05) for most AA, where corn did not respond to CP (P > 0.05). In SBM and MBM, the study effect improved the precision of the models. More negative intercepts, and significantly different from 0 (P< 0.002), were systematically obtained for faba beans, peas and barley indicating higher EL probably due to its high content of fiber and anti-nutritional factors. Among AA, intercepts were higher for Glu, Leu, Ser and Thr, which are predominant in the ileal digesta. In conclusion, CP can be a predictor of digestible AA of most AA for cereals, but not for SBM and MBM. Basal EL seems to be influenced by crude fiber and anti-nutritional factors.
Moro, Joanna. "Impact de la déficience en acides aminés indispensables sur le métabolisme protéique et énergétique, et identification de signatures métaboliques." Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASB001.
The availability of protein sources for human nutri-tion is a major concern due to global demographics, economics and nutritional transitions. Protein intakes must cover the need for nine indispensable amino acids (IAA). It is important that this need is met in order to avoid situations of protein and energy me-tabolism imbalance. Various studies have been de-veloped to determine this need: nitrogen balance, the factorial method, and methods using stable iso-topes. However, these methods are difficult and invasive, and the obtained values of needs present significant differences. It is therefore necessary to develop more precise and non-invasive approaches, such as metabolomics, as recommended by the FAO.The objectives of this thesis are to assess the impact of protein and IAA (lysine and threonine) deficiency on protein and energy metabolism and to identify markers of deficiency for these two amino acids in the growing rat. Severe levels of deficiency (85%; 75%) in protein and lysine and threonine decrease weight and lean mass and increase food intake. These effects are associated with a decrease in protein synthesis and an increase in energy metabolism in low protein diets. These effects seems to be mediated by FGF21. Analyses of metabolomics in urine show that variations in pipecolate and taurine indicate lysine and threonine deficiencies, respectively
Gaillard, Sandrine. "Détermination et différenciation sexuelles chez les poissons : "le sexe des esturgeons" : SPACne et "opeintre" devient "protéine"." Toulon, 2006. http://www.theses.fr/2006TOUL0019.
The sturgeon, family of Acipenseridae, is an ancestral fish, commercially very interesting and threatened of extinction. Sturgeons are raised for reintroduction in their environment and for the caviar production. Questions have remained as for its system of sex determination. We undertook to explore the genetic way of it, on the one hand by seeking molecular polymorphism by approaches of random screening, on the other hand by studying the expression of the genome by a technique of differential screening, SPACNE was developed in response to evolutions having to be operated on software SPAC previously created. A protein can from now on, only with its molecular weight and its aminoacids composition, be identified among the data of a protein or nucleic bank by the means of a more complete request and with more relevant results
Franck, Julien. "Développement des stratégies d’identification en mode bottom-up pour l’imagerie par spectrométrie de masse MALDI." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10079/document.
Since its introduction in 1997 by the group of R.M. Caprioli, direct tissue analysis and imaging by Mass Spectrometry have now become good complementary methods of classical proteomics techniques. Direct analysis of tissues gives access to the detection of hundreds of biomolecules while maintaining tissue integrity and by automation of this approach, molecular images of biomolecules distribution can be obtained in one step analysis. However, many developments need to be undertaken especially on the improvement of the detection of different classes of biomolecules including lipids, peptides and proteins. Moreover, if the localization of molecules of interest is possible but no structural information can obtained from proteins. If proteins identification can be delicate under classical proteomics conditions this is even truer by working directly on tissues. A bottom-up strategy will allow the identification and localization of proteins after MS/MS experiments of peptides generated after in situ enzymatic digestion. In most of cases, MS/MS is used to check the sequence of an expected endogenous peptide or obtained after digestion but MS/MS but spectra generated from instruments equipped with a MALDI ion source are often complex to analyze because of the different types of fragment series generated during the fragmentation process. This is especially true on MALDI-TOF systems that frequently for which weak fragmentations (especially in the higher m/z range of the MS/MS spectrum) and to very different series of fragment ions creating largely incomplete set of series only giving access to small sequence tags are often observed. Thus, we have studied on tissue N-terminal chemical derivatization of peptides for proteins identification in Bottom-up Imaging strategies. The derivatives promote efficient charge-site initiated cleavage of backbone amide bonds and they enable the selective detection of only a single series of fragment ions. Optimization of reactions were first performed at the whole tissue section scale and then modified and adapted to allow for the derivatization to be automatically performed using a micro-spotting piezoelectric automatic deposition device. Finally, we report a whole sequence of on tissue bottom up strategy followed by automatic derivatization and show that such strategies improve protein assignment and de novo sequencing directly from tissue sections, which is a key point for on tissue direct identification of markers
Petitdidier, Catherine. "Etude des modalités d'expression de certaines voies métaboliques de production d'arômes par des micro-organismes d'affinage des fromages à pâte pressée non cuite : précurseurs et systèmes enzymatiques impliqués dans le catabolisme des acides aminés." Clermont-Ferrand 2, 2002. http://www.theses.fr/2002CLF22334.
Larcheveque, Corine. "Nature et teneur des principaux acides aminés de la sève brute de Vinis Vinifera L. Var. Cabernet Franc aux stades phénologiques majeur du cycle végétatif : influence du millésime et du sol." Aix-Marseille 1, 1998. http://www.theses.fr/1998AIX11015.
Franck, Julien. "Développement des stratégies d’identification en mode bottom-up pour l’imagerie par spectrométrie de masse MALDI." Electronic Thesis or Diss., Lille 1, 2009. http://www.theses.fr/2009LIL10079.
Since its introduction in 1997 by the group of R.M. Caprioli, direct tissue analysis and imaging by Mass Spectrometry have now become good complementary methods of classical proteomics techniques. Direct analysis of tissues gives access to the detection of hundreds of biomolecules while maintaining tissue integrity and by automation of this approach, molecular images of biomolecules distribution can be obtained in one step analysis. However, many developments need to be undertaken especially on the improvement of the detection of different classes of biomolecules including lipids, peptides and proteins. Moreover, if the localization of molecules of interest is possible but no structural information can obtained from proteins. If proteins identification can be delicate under classical proteomics conditions this is even truer by working directly on tissues. A bottom-up strategy will allow the identification and localization of proteins after MS/MS experiments of peptides generated after in situ enzymatic digestion. In most of cases, MS/MS is used to check the sequence of an expected endogenous peptide or obtained after digestion but MS/MS but spectra generated from instruments equipped with a MALDI ion source are often complex to analyze because of the different types of fragment series generated during the fragmentation process. This is especially true on MALDI-TOF systems that frequently for which weak fragmentations (especially in the higher m/z range of the MS/MS spectrum) and to very different series of fragment ions creating largely incomplete set of series only giving access to small sequence tags are often observed. Thus, we have studied on tissue N-terminal chemical derivatization of peptides for proteins identification in Bottom-up Imaging strategies. The derivatives promote efficient charge-site initiated cleavage of backbone amide bonds and they enable the selective detection of only a single series of fragment ions. Optimization of reactions were first performed at the whole tissue section scale and then modified and adapted to allow for the derivatization to be automatically performed using a micro-spotting piezoelectric automatic deposition device. Finally, we report a whole sequence of on tissue bottom up strategy followed by automatic derivatization and show that such strategies improve protein assignment and de novo sequencing directly from tissue sections, which is a key point for on tissue direct identification of markers
Dossier, Berne Florence. "Analyse des acides aminés dans les eaux : développement et applications : incidence sur la consommation en chlore et la teneur en matière organique biodégradable des eaux potables : étude du mécanisme d'ozonation des peptides." Poitiers, 1994. http://www.theses.fr/1994POIT2349.
Gloaguen, Mathieu. "Identification des acides aminés limitants secondaires pour la croissance des porcelets dans des régimes à basse teneur en protéines et des mécanismes de régulation de la consommation volontaire lors d’une carence en valine." Rennes, Agrocampus Ouest, 2012. http://www.theses.fr/2012NSARB227.
Knowledge of amino acid requirements and the use of free AA in diets allow reducing the dietary crude protein(CP) content, improving the nitrogen efficiency and reducing the incidence of digestive disorders while maintaining performance of pigs. The 1st objective of the project was to identify the limiting amino acid for growth in low CP diets with a focus on valine (Val), isoleucine (Ile), leucine (Leu) and histidine (His). When the dietary Val supply is limiting, the voluntary feed intake of pigs decreases significantly. The underlying mechanisms have not yet been studied in pigs. The 2nd objective ws to contribute to the identification of mechanisms involved in feed intake regulation in pigs offered a diet deficient in Val. Our results indicated that a supply of 49 % Ile:Lys, 102 % Leu:Lys, and 32 % His:Lys (on a standardized ileal digestible bais) allows to maintain growth in pigs. The use of free Val, Leu, Ile, Phe and His enables a 4 percentage unit reduction in dietary CP content without affecting growth, which corresponds to a decrease of 40 % of nitrogen excretion. The feed intake reduction of a diet deficient in Val is the consequence of post-ingestive signals. The pig is able to detect a deficient supply of Val within A h after ingestion, which correspond to a low accumulation of plasma Val. In conclusion, our results show thaht it is possible to formulate very low CP diets for pigs and suggest implication of metabolic signals responsible for the reduction of feed intake when the diet is deficient in Val
Landry, Mantha Olivier. "Une nouvelle approche d’isotopomique pour identifier les dysrégulations du métabolisme des protéines et des acides aminés lors du développement du syndrome métabolique." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLA009/document.
Although the different components of the metabolic syndrome (MS) are likely to affect protein and amino acid (AA) metabolism, the available data are few and often contradictory, due to the heterogeneity of presentation of this syndrome and the limitations of classical approaches to investigate nitrogen metabolism. The present thesis work uses a novel isotopomic approach, based on the measurement of the natural abundance of stable isotopes of nitrogen (δ15N) and carbon (δ13C) in tissue proteins and AA to identify alterations in protein metabolism occurring during the nutritional induction of MS in rats. Our results allow to validate experimentally the predictions of a multi-compartimental model developed in the laboratory and showing that the δ15N reflects the differential orientation of AA between anabolic (proteosynthesis) and catabolic (oxidation) pathways. We have also shown that under certain conditions, the δ13C can allow to estimate the proportion of carbons in AA and tissue proteins issuing from dietary proteins, carbohydrates and lipids respectively, thus providing information on the metabolic flexibility of individuals. The measurements of δ15N and δ13C in proteins and AA, alone or combined with the measurement of protein synthesis rates after administration of deuterated water, then allowed us to highlight the changes in protein and AA metabolism occurring during perinatal and post-weaning exposure to a high-fat high-sugar diet, as well as those associated with individual differences in sensitivity to the induction of a MS by the same kind of diet. These alterations are tissuespecific and differ according to whether they result solely from differences in individual sensitivity to diet or whether they are also attributable to differences in the carbohydrate/lipid balance of the diet. Altogether, our results show that the development of MS is associated with changes in AA metabolic partitioning between the anabolic and oxidative pathways, differently affecting the liver, muscle, intestine and adipose tissue, and with an altered metabolic flexibility in muscle. This work opens the way to human studies, based on the measurements of δ15N and δ 13C in accessible pools
Bolea, Gaetan. "Oxydation des acides gras polyinsaturés n-6 au cours de la digestion et altération de la fonction vasculaire : Stratégie de prévention antioxydante par supplémentation en polyphénols de pomme Lipid protection by polyphenol-rich apple matrices is modulated by pH and pepsin in in vitro gastric digestion." Thesis, Avignon, 2019. http://www.theses.fr/2019AVIG0352.
According to the WHO, in 2030, nearly 23.6 million people will die of cardiovascular disease each year representing the leading cause of death as well as a major public health problem. Among these, ischemic diseases are the most common. They are the consequences of an endothelial dysfunction that promotes atherosclerosis development. The main risk factor associated with these pathologies is a Western diet rich in n-6 polyunsaturated fatty acids sensitive to oxidation by heme iron provided by red meat. In contrast, a diet rich in fruits, vegetables and grains can be a source of natural antioxidants such as polyphenols. Among polyphenols, procyanidins (PCs, flavonoids) appear correlated with a reduction of coronary heart disease and stroke. Thus, the aims of this work were: 1) to evaluate the potential formation of lipid oxidation products in the gastrointestinal tract during digestion, and their effects on the vascular function after absorption; 2) to evaluate the effects of a supplementation in apple PCs as a primary antioxidant strategy to prevent deleterious effects of lipid oxidation on the vascular function. First results were obtained in a sunflower oil-in-water emulsion as a model system with post-prandial stress brought by the addition of heme iron (metmyoglobin) in digestion conditions simulating the early and median phases of gastric digestion at pH 5 and 3, respectively. It appears that lipid oxidation, evaluated through the formation of lipid-derived conjugated dienes (CD) and 4-hydroxynonenal (4-HNE) is initiated more quickly at pH 3 than at pH 5. Pepsin promotes faster CD accumulation at pH 5 through the formation of a micro-metmyoglobin form that is likely more accessible to fatty acids. The three matrices (fresh apple, puree and phenolic extract) added at nutritional dose show a lower inhibitory capacity at pH 5, while higher at pH 3, in the presence of pepsin. This antioxidant strategy was then evaluated in a model of in vitro gastrointestinal digestion demonstrating a reduction of 73-96% in 4-HNE formation at the end of the gastric phase and 60-95% at the end of the intestinal phase. Finally, a chronic in vivo study was conducted to evaluate the impact of lipid oxidation in an ApoE-/- mouse model. The increase of lipid oxidation during digestion led to an increase in plasmatic oxidative stress and oxLDL levels resulting in an impairment of the endothelial function. This endothelial dysfonction was associated with an increased formation of atheromatous plaques that are potentially unstable. Interestingly, polyphenol supplementation (puree or phenolic extract) prevented the increase of plasmatic oxLDL as well as the development of endothelial impairments. Consequently, this treatment was able to prevent the development of atherosclerosis observed in our model. In conclusion, apple polyphenols could limit 4-HNE formation and absorption during digestion protecting the vascular function in the long-term. Our results are in favor of a reintroduction of PCs-rich fruits (apple, pear) in the Western diet
Deramoudt, François-Xavier. "Contribution à l'étude du métabolisme des cellules lymphoblastoïdes en culture continue in vitro." Compiègne, 1990. http://www.theses.fr/1990COMPD234.
Human lymphoblastoid cells, secreted a monoclonal anti-Rh(D) antibody (Mab) were cultivated in a chemostat using stirred bioreactor with serum-free medium. Then, we studied different dilution rates to obtain the optimal steady-state. We analysed the response of lymphoblastoid cells growth rate, metabolism and Mab production to step change in oxygen supply and to decrease of glucose feeding rate. The steady state concentration of viables cells increase with increasing dissolved oxygen (DO) up to 60% air saturation or with decreasing DO until critical value of I5 to 5% air saturation. The optimum DO for Mab production was 30 %. Glucose consumption and glycolisis were enhanced at lower concentration. Reduction of glucose concentration in the bioreactor, by means of independent glucose feeding, enhanced the growth but did not significantly affect Mab production. Furthermore, the fraction of glucose converted to lactate was reduced. Alterations in amino-acid metabolism have been observed. Experiments were carried out in order to study the effect of constituents medium concentration on cell growth and Mab production which show an effective dissociation between growth and Mab production. General strategy for continuous cell culture will be discussed
Sebih, Fatiha. "La théanine et ses dérivés : synthèse stéréosélective et évaluation biologique sur la synapse glutamatergique." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20204.
L-Theanine (5-N-L-ethylglutamine) which is an amino acid found in green tea, it has a structure similar to that of glutamic acid. L-theanine has the ability to cross the blood-brain barrier in addition to its physiological and pharmacological activities.Given the importance of this molecule as essential for the investigation of physiological roles of CNS tools, we synthesized the enantiomerically pure theanine (L and D). A serie of 5-N-substituted theanine were also synthesized. In order to broaden the range of applications of theanine, we synthesized dipeptides containing Theanine for the purpose of obtaining products that have biological significance. The regio and stereoselectively synthesized analogs of L-theanine in the 4-position substituted with an aryl group has been developed to be tested at the level of glutamate receptors.The results of biological tests, using calcium imaging technique, show that theanine with its two enantiomers (D and L) has an agonistic effect vis-à-vis the NMDA receptors and that this effect was much greater with the enantiomer (D). Among the 5-N-alkylated analogs of theanine which they had only an agonistic effect on the NMDA receptor, 5-N-Propyl-Gln (L and D) has activity as an agonist much larger than the theanine and no effects were scored on AMPA receptors and metabotropic. L-theanine and its derivatives could be interesting structures to develop new pharmacological tools to study glutamate receptors (metabotropic and / or ionotropic)