Glutamate and CO2 production from glutamine in incubated enterocytes of adult and very old rats.

Glutamine is the major fuel for enterocytes and promotes the growth of intestinal mucosa. Although oral glutamine exerts a positive effect on intestinal villus height in very old rats, how glutamine is used by enterocytes is unclear. Adult (8 months) and very old (27 months) female rats were exposed to intermittent glutamine supplementation for 50% of their age lifetime.

Intestinal inflammation increases gastrointestinal threonine uptake and mucin synthesis in enterally fed minipigs.

The high requirement of the gut for threonine has often been ascribed to the synthesis of mucins, secreted threonine-rich glycoproteins protecting the intestinal epithelium from injury. This requirement could be even greater during intestinal inflammation, when mucin synthesis is enhanced. In this study, we used an animal model to investigate the effects of an acute ileitis on threonine splanchnic fluxes.

Converting nitrogen into protein--beyond 6.25 and Jones' factors.

The protein content in foodstuffs is estimated by multiplying the determined nitrogen content by a nitrogen-to-protein conversion factor. Jones' factors for a series of foodstuffs, including 6.25 as the standard, default conversion factor, have now been used for 75 years.

Differential response of protein metabolism in splanchnic organs and muscle to pectin feeding.

The aim of the present study was to determine whether the addition of soluble fibre in the diet affected protein metabolism in the intestinal tissues, some visceral organs and in skeletal muscle. A diet supplemented with pectin (80 g/kg) was fed to young growing rats and the effect on organ mass and protein metabolism in liver, spleen, small and large intestines and gastrocnemius muscle was monitored and compared with the control group. Protein synthesis rates were determined by measuring [13C]valine incorporation in tissue protein.

Peptides reproducibly released by in vivo digestion of beef meat and trout flesh in pigs.

Characterisation and identification of peptides (800 to 5000 Da) generated by intestinal digestion of fish or meat were performed using MS analyses (matrix-assisted laser desorption ionisation time of flight and nano-liquid chromatography electrospray-ionisation ion trap MS/MS). Four pigs fitted with cannulas at the duodenum and jejunum received a meal exclusively made of cooked Pectoralis profundus beef meat or cooked trout fillets. A protein-free meal, made of free amino acids, starch and fat, was used to identify peptides of endogenous origin.

Postprandial whole-body protein metabolism after a meat meal is influenced by chewing efficiency in elderly subjects.

Background: The rate of protein digestion affects protein utilization in elderly subjects. Although meat is a widely consumed protein source, little is known of its digestion rate and how it can be affected by the chewing capacity of elderly subjects.

Objectives: We used a [1-(13)C]leucine balance with a single-meal protocol to assess the absorption rate of meat protein and to estimate the utilization of meat protein in elderly subjects with different chewing efficiency.

Carnosine concentration of ingested meat affects carnosine net release into the portal vein of minipigs.

Because of its physiological effects, carnosine (beta-alanyl-L-histidine) can be considered as a bioactive food component. The objective of this study was to assess the quantitative significance of intact carnosine absorption after ingestion of different beef meats, using the minipig as animal model. In a preliminary experiment, we evaluated the level of dietary carnosine in intestinal digesta of pigs (n = 4) after a meat meal (0.

Dietary conjugated linoleic acid has limited effects on tissue protein anabolism in sedentary and exercising adult rats.

The effects of conjugated linoleic acid isomers (CLA) and endurance training on lean body mass are expected to result from their action on tissue protein metabolism. The aim of this study was to analyze their effects on protein metabolism in 2 muscles, the small intestine and liver of adult rats. Four-month-old male Wistar rats were fed diets containing either no CLA, cis-9, trans-11 CLA isomer (1 g.

Dietary pectin stimulates protein metabolism in the digestive tract.

Objective: The aim of this study was to determine if protein metabolism was altered in small and large intestines by feeding pectin, a soluble fiber known to stimulate cecal production of short-chain fatty acids (SCFAs) and to have a trophic effect in these tissues.

Methods: Twenty-four weanling male Sprague-Dawley rats were fed ad libitum for 14 d with a balanced control diet or an isoproteic, isocaloric pectin (citrus) diet (80 g/kg). SCFA production, intestinal histomorphometry, and protein synthesis were determined in the proximal and distal parts of the small intestine, the cecum, and the colon.

Methionine kinetics are altered in the elderly both in the basal state and after vaccination.

Background: Inflammation is known to affect sulfur amino acid metabolism. Aging is associated with an increased prevalence of inflammatory conditions, but the metabolism of methionine has been poorly explored in the elderly.

Objectives: The aims of this study were to compare methionine kinetics between elderly and young subjects and to explore the effect of aging on the response to a mild inflammatory challenge induced by a vaccination.

Differential effects of cooked beans and cooked lentils on protein metabolism in intestine and muscle in growing rats.

Aims: The effect of diets based on cooked beans or lentils on protein metabolism in intestines and muscles was studied in rats.

Method: The cooked seeds were used as the unique protein source in balanced diets (containing 229 and 190 g of crude protein per kg dry matter) fed to young growing rats for 20 days. Their effects were compared with those of the control casein diet in pair-fed rats.

Altered responses in skeletal muscle protein turnover during aging in anabolic and catabolic periods.

One of the most important effects of aging is sarcopenia, which is associated with impaired locomotion and general weakness. In addition, there is increased susceptibility to illness in aging, which often results in muscle wasting episodes. In such instances, the mobilization of muscle proteins provides free amino acids that are used for energetic purpose, the synthesis of acute phase proteins, and the immune response.

The inflammatory response to vaccination is altered in the elderly.

To further explore whether immune function and acute phase response are altered during ageing, the response to a mild inflammatory stress (DT-Polio-Typhim vaccination) was studied in elderly and young subjects. Cytokine production (IFN-gamma, TNF-alpha, IL-6, IL-10) by whole blood cultures, circulating cytokines and acute phase proteins were analysed before and 2 days after vaccination. Prior to vaccination, only IFN-gamma production was lower in the elderly than in the young subjects due to a lower mononuclear cell number.

Isomers of conjugated linoleic acid decrease plasma lipids and stimulate adipose tissue lipogenesis without changing adipose weight in post-prandial adult sedentary or trained Wistar rat.

The respective effects and interactions of supplementation with two conjugated linoleic acid (CLA) isomers and exercise on plasma metabolic profile, activity of lipogenic enzymes and cellularity in two adipose tissue sites, those of the liver and heart, were examined in adult Wistar rats. Rats that were either sedentary or exercise-trained by treadmill running were fed one of four diets: a diet without CLA; a diet with either 1% cis 9, trans 11 CLA or 1% trans 10, cis 12 CLA; or a mixture of both isomers (1% of each) for 6 weeks. We observed that the exercise decreased lipogenic enzyme activities in epididymal and perirenal adipose tissue.

Differential effects of cooked common bean (Phaseolus vulgaris) and lentil (Lens esculenta puyensis) feeding on protein and nucleic acid contents in intestines, liver and muscles in rats.

Aim: Our aim was to investigate the influence of legume feeding on the protein and nucleic acid content of intestinal tissues and muscles.

Methods: Growing male Wistar rats were fed ad libitum on balanced diets containing cooked common bean or lentil as the unique protein source (180 g.kg(-1) dry matter) for 20 days.

Cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid isomers do not modify body composition in adult sedentary or exercised rats.

Dietary CLA isomers were shown to reduce adipose tissues in growing animals, mainly in mice, but their effects in adult animals remain unclear. This study was conducted to determine whether these effects depend on the isomer fed, on physical activity, or on the initial level of body fat. Male Wistar rats (4 mo old) were fed for 6 wk diets containing either no CLA, the cis-9, trans-11 CLA isomer (10 g/kg), the trans-10, cis-12 CLA isomer (10 g/kg), or both isomers (10 g/kg each).

Differential variation of mitochondrial H2O2 release during aging in oxidative and glycolytic muscles in rats.

Mitochondrial free radical (ROS) production could be involved in sarcopenia. Our aim was to measure this production in various muscles during aging. Male Wistar rats aged 4.

Age-related changes in glutathione availability and skeletal muscle carbonyl content in healthy rats.

The free radical theory of aging proposes that oxidative stress plays a key role in the aging process. By altering muscle protein degradation rates, it could accelerate the age-related loss of muscle proteins. Glutathione (GSH), one of the main body antioxidants, could prevent this phenomenon, but its concentration decreases during aging.

Differential effect of lentil feeding on proteosynthesis rates in the large intestine, liver and muscle of rats.

The aim of this work was to test the hypothesis that the trophic effect of lentil feeding on large intestine results from a stimulation of protein synthesis and to determine whether it interferes with protein metabolism in other splanchnic or peripheral organs. Two groups of growing Sprague Dawley male rats were pair-fed iso-caloric iso-nitrogenous balanced diets containing either cooked lentils (Lens esculenta puyensis) or casein as unique protein source. Protein synthesis rates were measured in vivo, in large intestine, liver and gastrocnemius at the postprandial state.

Daily protein intakes and eating patterns in young and elderly French.

An adequate level of protein intake is required to limit the gradual body protein loss observed during ageing. Different factors (cohort age, sex, life conditions) may modify protein intake and distribution. However the precise amounts, as well as their daily distribution which affects protein utilisation and N retention, are unknown in both young and elderly individuals.

Type and timing of protein feeding to optimize anabolism.

Purpose Of Review: The delivery rate of amino acids to an organism significantly affects protein anabolism. The rate can be controlled by the type and the timing of feeding. Our aim was to bring new insights to the way they may act.

Chronic inflammation alters protein metabolism in several organs of adult rats.

Despite the prevalence of chronic inflammatory diseases in developed countries, few studies have considered the metabolic alterations observed in these disorders. To determine which perturbations in protein metabolism occur during chronic inflammation, and the consequences they have on nutritional requirements, a model of ulcerative colitis was adapted for use in adult rats. Adult Sprague-Dawley male rats (9 mo old) received dextran sulfate sodium (DSS) in their drinking water at 50 g/L for 9 d, then at 20 g/L for 18 d.

Pulse protein feeding pattern restores stimulation of muscle protein synthesis during the feeding period in old rats.

Muscle loss during aging could be related to a lower sensitivity of muscle protein synthesis to feeding. To overcome this decrease without increasing protein intake, we proposed to modulate the daily protein feeding pattern. We showed that consuming 80% of dietary proteins at noon (pulse pattern) improved nitrogen balance in elderly women.