Biomedical subjects

Philippe Patureau Mirand

Publications and source records attributed to Philippe Patureau Mirand.

16 recordsLinked to original sources

PubMed2006

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.100 g(-1)), trans-10, cis-12 CLA isomer (1 g.100 g(-1)) or both isomers (1 g.100 g(-1) each) for 6 weeks. Half of the rats were subjected to endurance training by running on a treadmill. At the end of this period, the rats were injected with a flooding dose of (13)C-valine to determine protein synthesis rates in the post-absorptive (experiment 1) and in the post-prandial (experiment 2) states. No effect of CLA or endurance training were detected in the small intestine. Training reduced food intake and protein synthesis rates in the liver but no effect was found on the protein synthesis rates in muscles. In the post-absorptive state, protein synthesis rate was increased by feeding the trans-10, cis-12 CLA isomer alone in the liver (+9%) or in combination with the cis-9, trans-11 isomer in the gastrocnemius (+30%), mostly in sedentary rats. In the post-prandial state, the cis-9, trans-11 CLA isomer tended to reduce the protein synthesis rate in the gastrocnemius muscle. However, no effect of CLA was found on muscle protein amounts. In conclusion, CLA isomers would have limited but differential effects on tissue protein metabolism in adult rats.

Animals↗

PubMed2006

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. Protein synthesis rates were determined by measuring the (13)C valine incorporation rate in tissue proteins. RESULTS: Pectin feeding slightly decreased food intake and growth rate. It increased the acetate, propionate, and butyrate pools in the cecum. Pectin feeding resulted in heavier intestinal tissues corresponding to higher villus height in the small intestine and crypt depth in the small and large intestines compared with feeding of the control diet. Compared with the control group, the rats fed the pectin diet had significantly higher protein synthesis rates in all the parts of their intestines. CONCLUSION: Supplementation of pectin, as a soluble fiber, in the diets, stimulated SCFA production, had a trophic effect on the different parts of the intestines, and greatly stimulated protein synthesis in those tissues.

Animals↗

PubMed2006

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. Protein synthesis rates in small and large intestines and in gastrocnemius and soleus muscles were determined in vivo, in a fed state, by the flooding dose method, using 13C-valine. RESULTS: In the small and large intestine tissues of the legume fed groups, protein, RNA relative masses (mg.100 g BM(-1)) and protein synthesis rates (FSR and ASR) were higher than in the control rats (p < 0.05). In gastrocnemius and soleus muscles,protein and RNA contents (in mg) and protein synthesis rates were significantly (p < 0.05) lower in the legume-fed groups than in the control rats. CONCLUSION: The chronic intake of cooked legumes increased protein synthesis rates in intestinal tissues and decreased them in muscles. This effect was greater for beans than for lentils in the large intestine and in gastrocnemius muscle.

Animals↗

PubMed2006

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. DESIGN: Seven elderly volunteers aged 66-76 y and 8 young volunteers aged 22-26 y were studied before and 2 d after a vaccination (diphtheria, tetanus, poliomyelitis, and typhoid vaccines). Methionine kinetics were measured by using an infusion of L-[1-13C, methyl-2H3]methionine in the postabsorptive and fed states. RESULTS: Before vaccination, the contribution of homocysteine remethylation to methionine-methyl flux (Qm) and the ratio of remethylation to homocysteine transsulfuration were significantly lower in the elderly subjects than in the young subjects (P < 0.05). In contrast, the contribution of transsulfuration to methionine transmethylation was higher in the elderly (P < 0.05). Vaccination significantly increased the ratio of transsulfuration to transmethylation and decreased the ratio of remethylation to Qm (P < 0.05). CONCLUSIONS: The preferential methionine metabolism toward cysteine synthesis observed after vaccination suggests an increased requirement of sulfur amino acids even in mild inflammatory situations. The main finding of this study is a higher proportion of methionine entering the transsulfuration pathway in elderly subjects before vaccination. This finding suggests an increased cysteine demand during aging.

Adult↗

PubMed2005

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. In the same time, although in the normal range, several acute phase proteins were greater in elderly than in young subjects, suggesting a low-grade inflammatory state in the elderly. After vaccination, IFN-gamma production remained lower in the elderly than in the young, supporting an altered cell-mediated immunity with advancing age. TNF-alpha production was unaffected by either ageing or vaccination. IL-6 production was stimulated by vaccination in young subjects but not significantly in the elderly. IL-10 production was inhibited by vaccination in the elderly but not in the young. Acute phase proteins were less increased in elderly than in young subjects. Taken together, these results support a general lack of inflammatory response in the elderly exposed to an immune challenge and suggest that immune deficiency may concern both Th1 and Th2 responses. However, the interpretation must respect the limitation of small subjects number.

Acute-Phase Proteins↗

PubMed2005

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. However, since muscle protein mass is already depleted, the ability of the aged organism to recover from stress is impaired. Therefore, elucidating the mechanisms that result in sarcopenia is of obvious importance. Age-related changes in protein synthesis and proteolysis are rather small and our current methodology does not enable one to establish unequivocally whether sarcopenia results from depressed protein synthesis, increased proteolysis or both. By contrast, in anabolic and catabolic periods, a number of dysregulations in muscle protein turnover became clearly apparent. The aim of this review is to provide an overview of such altered responses to nutrients and catabolic treatments, which may ultimately contribute to explain sarcopenia. This includes impaired recovery in catabolic states, impaired anabolic effects of nutrients, in particular leucine, and a lack of regulation of the ubiquitin-proteasome proteolytic system. These alterations are discussed with respect to modifications in the insulin/IGF-1 axis and glucocorticoid related effects.

Aging↗

PubMed2004

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. The control group was pair-fed with an iso-energetic, iso-nitrogenous balanced casein diet. RESULTS: Intestinal tissues were heavier in the legume-fed groups and higher relative mass (g per 100 g body mass) of protein, RNA and DNA were found in these tissues as compared to those of the control groups. In liver protein and RNA masses were significantly lower in the bean group than in the control group but the DNA content was not different in the legume and in the control groups. In gastrocnemius and soleus muscles, there was no significant effect of legume feeding on the fresh mass and on the protein and RNA contents, but the DNA content of the m. gastrocnemius was significantly lower in both legume groups than in their control group. The ribosomal capacity of intestines, liver and muscles was not significantly affected by legume feeding. CONCLUSION: Legume feeding had a trophic effect on both proximal and distal intestinal tissues; dietary fiber appears to be the main cause of this effect.

Animals↗

PubMed2004

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. Our aims were to have a better understanding of the mechanisms of the age-related decrease in glutathione availability and of the links with sarcopenia. Male Wistar rats aged 6, 9, 12, 15, 19, 22, 25 and 28 months (n = 6 per age) were used to measure plasma and skeletal muscle protein carbonyl content, plasma total and free cyst(e)ine content, liver and muscle glutathione content as well as liver GSSG reductase, GSH peroxidase, GSH transferase and gamma glutamyl cysteine synthetase (GCS) activities. Although tissue glutathione content decreased with age, the other markers of oxidative stress were little changed during aging. In particular, muscle protein carbonyl content was unchanged. Variations in glutathione availability were not explained by cyst(e)ine availability but depended on gamma GCS activity. The stability of skeletal muscle carbonyl content during aging suggests a very efficient degradation of oxidized proteins in muscle.

Aging↗

PubMed2004

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. In large intestine, protein and ribonucleic acid contents were higher in the lentil-fed group than in the control group, and the amount of proteins synthesized was also higher (+57%). By contrast, liver protein and ribonucleic acid contents as well as protein synthesis rates were significantly lower in the lentil-fed group than in the control group. In the gastrocnemius muscle protein and ribonucleic acid contents were significantly lower and the amount of protein synthesized was also lower (-18%) in the lentil fed group than in the control group. This study suggests that stimulation of protein synthesis in the large intestine is compensated for by a decrease in liver and muscle.

Animal Feed↗

PubMed2004

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. Plasma cholesterol, insulin, and leptin concentrations were lower in exercise-trained rats than in sedentary rats. The ingestion of either CLA mixture or the trans 10, cis 12 CLA increased lipogenic enzyme activities in epididymal tissue and more markedly in perirenal adipose tissue, especially in sedentary rats, and without affecting adipose tissue weight or cellularity. A similar effect of trans 10, cis 12 CLA was observed in regard to malic enzyme activity in the liver. In addition, this isomer decreased plasma lipid and urea concentrations and increased plasma 3-hydroxybutyrate levels. The ingestion of cis 9, trans 11 CLA increased fatty acid synthase activity in perirenal adipose tissue in sedentary rats and decreased plasma cholesterol and leptin concentrations. These results show that isomers of CLA decrease plasma lipids and stimulate adipose tissue lipogenesis without changing adipose weight in adult sedentary or exercise-trained rat, thus suggesting a stimulation of adipose tissue turnover.

Adipose Tissue↗

PubMed2004

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 4.5 and 24 months were used. H(2)O(2) release and protein carbonyls were evaluated in isolated mitochondria from an oxidative (soleus) and a glycolytic (tibialis anterior) muscle. Total and Mn-superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX) and glutathione reductase (GR) activities were measured in tibialis anterior. In soleus, glutamate/malate supported mitochondrial H(2)O(2) release was lower than in tibialis anterior in young rats, but increased significantly with age. In tibialis anterior, glutamate/malate or succinate supported H(2)O(2) release was unchanged with age. ROS generators were complexes I and III. Mitochondrial carbonyl content remained stable during aging in both muscles but tended to be higher in tibialis anterior than in soleus. Tibialis anterior total SOD (+17%), catalase (+84%), and GPX (-17%) activities varied significantly with age but Mn-SOD was unchanged, suggesting an increase in cytosolic ROS production. In conclusion, the higher life-long H(2)O(2) release observed in tibialis anterior is consistent with the known sensitivity of glycolytic muscles to sarcopenia. The fact that the rate of H(2)O(2) release increases with age in soleus seems to have little impact.

Aging↗

PubMed2004

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). Half of the rats were assigned to exercise by treadmill running (1 h/d, 22 m/min). The initial body fat level was normal (12.7%) in a first trial, and high (18.9%) in a second trial. Chemical and anatomical body compositions were determined by chemical analysis and organ dissection. In both trials, the CLA diets, whatever the isomer, had no effect on food intake and body weight changes, on body chemical composition (fat, protein and water contents or gains), or on the body anatomical composition (weights or gains in epididymal and perirenal adipose tissues, in liver and in 4 muscles). There was no interaction between CLA treatment and physical activity. In conclusion, adult male rats do not appear to be responsive to the fat-to-lean partitioning effect of CLA described in growing rats. This was not affected by exercise or initial body fat level.

Animals↗

PubMed2003

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. The hypothesis was tested that protein intake and its distribution over daily meals could be different between the young and elderly. The consumption of six different protein-rich food groups by 292 healthy individuals aged 20-30 and 65-75 years was determined throughout each day for 1 week. The data of the total protein intake and protein intakes at each meal were analysed by ANOVA for each sex separately, using age group as the independent factor. The average protein intake of men was lower in the older age group whilst the opposite trend was seen in women. The distribution of protein intake was different between the two age groups: 56.5 % of the daily protein was eaten at lunch by the elderly but only 47 % (P<0.0001) by the younger subjects. In the elderly subjects, those eating larger amounts consumed a greater proportion of protein-rich foods at dinner than those eating small amounts (30.4 v. 26.2 %, P=0.05). A high level of protein intake was related to a higher meat-product consumption in both the elderly and young individuals. In conclusion, the pattern of protein intake differs significantly between age groups and sexes.

Adult↗

PubMed2003

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. RECENT FINDINGS: During young and adult ages, when food supply is liberal, subjects can adapt to various modes of protein feeding. However, during food restriction, protein anabolism is favored when the delivery of amino acids is evenly distributed over the day, either with frequent meals, or through the use of slowly absorbed proteins like casein. In contrast, during aging, quickly absorbed protein sources become more efficient. During recovery after exercise, the timing of protein feeding after the end of exercise may or may not influence its anabolic effect, depending on the subject's age and the type of exercise. SUMMARY: The synchronization of variations in anabolic capability with amino acid supply partly explains the effects of the type and timing of protein feeding. This effect is modulated by the amount of amino acids required to increase whole-body proteins and by the signaling properties of some amino acids to stimulate protein synthesis. Indeed, the anabolic effect of amino acids is determined by their interaction with other anabolic factors (other nutrients or physiological factors, whose efficiency is mainly related to their effect on protein degradation). It is clear that benefits can be obtained from adapted protein feeding patterns.

Absorption↗

PubMed2002

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. The present study was undertaken in rats to determine which tissues are the targets of the pulse pattern and what mechanisms are involved. Male Sprague-Dawley 11- and 23-mo-old rats (n = 32 per age) were fed 4 isoproteic (18% protein) meals/d for 10 d. Then half of the rats at each age were switched to a 11/66/11/11% repartition of daily proteins (pulse pattern) for 21 d. On d 21, rats were injected with a flooding dose of L-(13)C-valine (50 atom% excess, 150 micromol/100 g body) and protein synthesis rates were measured in liver, small intestine and gastrocnemius muscle in either the postabsorptive or the fed state. Epitrochlearis muscle degradation rates and plasma amino acid concentrations were measured at the same times. The pulse pattern had the following effects: 1) it significantly increased liver protein synthesis response to feeding and postprandial plasma amino acid concentrations at both ages; 2) it restored a significant response to feeding of gastrocnemius muscle protein synthesis in old rats; and 3) it had no effect in small intestine or on muscle breakdown. Thus, using a pulse pattern could be useful in preventing the age-related loss of muscle by increasing feeding-induced stimulation of muscle protein synthesis.

Aging↗

PubMed2002

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. A group of control rats, matched for age and weight, was pair-fed to the treated rats. DSS induced body weight loss and chronic inflammation characterized by an increase of spleen, liver, ileum and colon weights, of blood leukocytes and acute-phase protein levels. The main inflammatory site was the colon, which presented characteristic histological alterations and increased myeloperoxydase activity. Inflammation was accompanied by oxidative stress, characterized by increased plasma protein carbonyl content and increased liver glutathione concentration, but decreased glutathione concentration in muscle. This DSS-induced colitis led to a stimulation of protein synthesis in spleen (+223%), ileum (+40%) and colon (+63%). By contrast, protein synthesis in muscle slowed down (-23%). In conclusion, like acute inflammation, chronic inflammation induced a stimulation of protein metabolism in several splanchnic organs. In muscle, both protein synthesis and degradation were reduced. Taken together, these data are consistent with inadequate amino acid supply to meet the increased requirement resulting from chronic inflammation.

Amino Acids↗