Contribution of plasma proteins to splanchnic and total anabolic utilization of dietary nitrogen in humans

2003 ◽  
Vol 285 (1) ◽  
pp. E88-E97 ◽  
Author(s):  
Hélène Fouillet ◽  
Claire Gaudichon ◽  
Cécile Bos ◽  
François Mariotti ◽  
Daniel Tomé
Keyword(s):  
Amino Acids ◽  
Compartmental Model ◽  
Current Knowledge ◽  
Mixed Meal ◽  
Experimental Conditions ◽  
Dietary Nitrogen ◽  
Peripheral Proteins ◽  
N Incorporation ◽  
Invasive Techniques ◽  
Meal Ingestion

Splanchnic tissues are largely involved in the postprandial utilization of dietary amino acids, but little is yet known, particularly in humans, about the relative contributions of different splanchnic protein pools to splanchnic and total postprandial anabolism. Our aim was to develop a compartmental model that could distinguish dietary nitrogen (N) incorporation among splanchnic constitutive, plasma (splanchnic exported), and peripheral proteins after a mixed-protein meal in humans. Eight healthy subjects were fed a single mixed meal containing 15N-labeled soy protein, and dietary N postprandial kinetics were measured in plasma free amino acids, proteins, and urea and urinary urea and ammonia. These experimental data and others previously obtained for dietary N kinetics in ileal effluents under similar experimental conditions were used to develop the compartmental model. Six hours after the mixed-meal ingestion, 31.5, 7.5, and 21% of ingested N were predicted to be incorporated into splanchnic constitutive, splanchnic exported, and peripheral proteins, respectively. The contribution of splanchnic exported proteins to total splanchnic anabolism from dietary N was predicted to be ∼19% and to remain steady throughout the simulation period. Model behavior and its predictions were strongly in line with current knowledge of the system and the scarce, specific data available in the literature. This model provides the first data concerning the anabolism of splanchnic constitutive proteins in the nonsteady postprandial state in humans. By use of only slightly invasive techniques, this model could help to assess how the splanchnic anabolism is modulated under different nutritional or pathophysiological conditions in humans.

Exogenous amino acids stimulate human muscle anabolism without interfering with the response to mixed meal ingestion

2005 ◽  
Vol 288 (4) ◽  
pp. E761-E767 ◽  
Author(s):  
Douglas Paddon-Jones ◽  
Melinda Sheffield-Moore ◽  
Asle Aarsland ◽  
Robert R. Wolfe ◽  
Arny A. Ferrando
Keyword(s):  
Amino Acids ◽  
Metabolic Response ◽  
Essential Amino Acids ◽  
Constant Infusion ◽  
Intact Protein ◽  
Control Group ◽  
Mixed Meal ◽  
Fractional Synthetic Rate ◽  
Meal Protein ◽  
Meal Ingestion

We sought to determine whether ingestion of a between-meal supplement containing 30 g of carbohydrate and 15 g of essential amino acids (CAA) altered the metabolic response to a nutritionally mixed meal in healthy, recreationally active male volunteers. A control group (CON; n = 6, 38 ± 8 yr, 86 ± 10 kg, 179 ± 3 cm) received a liquid mixed meal [protein, 23.4 ± 1.0 g (essential amino acids, 14.7 ± 0.7 g); carbohydrate, 126.6 ± 4.0 g; fat, 30.3 ± 2.8 g] every 5 h (0830, 1330, 1830). The experimental group (SUP; n = 7, 36 ± 10 yr, 87 ± 12 kg, 180 ± 3 cm) consumed the same meals but, in addition, were given CAA supplements (1100, 1600, 2100). Net phenylalanine balance (NB) and fractional synthetic rate (FSR) were calculated during a 16-h primed constant infusion of l-[ ring-2H5]phenylalanine. Ingestion of a combination of CAA supplements and meals resulted in a greater mixed muscle FSR than ingestion of the meals alone (SUP, 0.099 ± 0.008; CON, 0.076 ± 0.005%/h; P < 0.05). Both groups experienced an improvement in NB after the morning (SUP, −2.2 ± 3.3; CON, −1.5 ± 3.5 nmol·min−1·100 ml leg volume−1) and evening meals (SUP, −9.7 ± 4.3; CON, −6.7 ± 4.1 nmol·min−1·100 ml leg volume−1). NB after CAA ingestion was significantly greater than after the meals, with values of 40.2 ± 8.5 nmol·min−1·100 ml leg volume−1. These data indicate that CAA supplementation produces a greater anabolic effect than ingestion of intact protein but does not interfere with the normal metabolic response to a meal.

Leucine and phenylalanine kinetics during mixed meal ingestion: a multiple tracer approach

1992 ◽  
Vol 262 (4) ◽  
pp. E455-E463 ◽  
Author(s):  
G. Biolo ◽  
P. Tessari ◽  
S. Inchiostro ◽  
D. Bruttomesso ◽  
C. Fongher ◽  
...  
Keyword(s):  
Amino Acids ◽  
Steady State ◽  
Whole Body ◽  
Mixed Meal ◽  
Normal Volunteers ◽  
Dietary Amino Acids ◽  
Leucine Kinetics ◽  
Meal Ingestion

To estimate whole body and splanchnic metabolism of dietary amino acids, phenylalanine and leucine kinetics were determined simultaneously in six normal volunteers before and during the constant administration of a complete mixed meal, employing multiple tracers of these amino acids. L-[5,5,5-2H]leucine and L-[2,6-3H]-phenylalanine were infused intravenously; L-[1-13C]leucine and L-[1-14C]phenylalanine were administered orally with the meal. During the meal, steady-state leucine concentration rose from 136 +/- 6 to 190 +/- 14 mumol/l (P less than 0.01), phenylalanine from 44 +/- 4 to 61 +/- 6 mumol/l (P less than 0.01), total leucine rate of appearance (Ra) from 1.29 +/- 0.03 to 1.77 +/- 0.07 (P less than 0.01, +37 +/- 3%), and phenylalanine Ra from 0.73 +/- 0.05 to 0.80 +/- 0.07 mumol.kg-1.min-1 (P less than 0.05, +8 +/- 3%). Splanchnic uptake of dietary phenylalanine was greater (P less than 0.001) than that of leucine (58 +/- 4 vs. 25 +/- 4%, respectively), 44 +/- 3% of circulating leucine derived from the diet vs. 20 +/- 2% of circulating phenylalanine (P less than 0.01). Endogenous leucine and phenylalanine Ra were significantly suppressed (P less than 0.05). In summary: 1) splanchnic uptake of dietary phenylalanine is onefold greater than that of leucine; 2) dietary contribution to systemic phenylalanine Ra is about half of that to leucine Ra; and 3) endogenous appearance of both leucine and phenylalanine after the meal is suppressed. In conclusion, splanchnic metabolism of dietary leucine and phenylalanine differs markedly and can be quantitated in vivo without catheterization.

Schistosoma mansoni: tail loss in relation to permeability changes during cercaria–schistosomulum transformation

Parasitology ◽  
1975 ◽  
Vol 71 (1) ◽  
pp. 9-18 ◽  
Author(s):  
R. E. Howells ◽  
S. E. Gerken ◽  
F. J. Pinto-Ramalho ◽  
U. Kawazoe ◽  
G. Gazzinelli ◽  
...  
Keyword(s):  
Amino Acids ◽  
Methylene Blue ◽  
Schistosoma Mansoni ◽  
Body Region ◽  
Experimental Conditions ◽  
General Body ◽  
Tail Loss ◽  
Permeability Changes ◽  
Extensive Lesion ◽  
Scanning Electron

The hind-body region of Schistosoma mansoni cercariae observed in the scanning electron microscope demonstrates various stages of contraction which may be compared with those of living larvae which are secreting the acetabular gland contents.No evidence for an extensive lesion was found in cercarial bodies which had shed their tails under experimental conditions. Experiments on the permeability of the larvae to sodium fluoride, methylene blue and amino acids demonstrated that tail loss significantly affects the permeability of the bodies although the effect is greater immediately after decaudation than at later times. Subsequent increases in permeability may be correlated with a change in the general body surface.

scholarly journals Plant growth and solute accumulation and distribution in two sorghum genotypes, under NaCl stress

2001 ◽  
Vol 13 (3) ◽  
pp. 270-284 ◽  
Author(s):  
CLAUDIVAN FEITOSA DE LACERDA ◽  
JOSÉ CAMBRAIA ◽  
MARCO ANTONIO OLIVA CANO ◽  
HUGO ALBERTO RUIZ
Keyword(s):  
Amino Acids ◽  
Root System ◽  
Nacl Stress ◽  
Soluble Carbohydrates ◽  
Saline Stress ◽  
Organic Solutes ◽  
Experimental Conditions ◽  
Absolute Increase ◽  
Sorghum Genotypes ◽  
Sensitive Genotype

Seedlings of two sorghum (Sorghum bicolor (L.) Moench) genotypes with differential tolerance to salinity were exposed to 0 and 100 mM NaCl, gradually added in increments of 25 mM every 12 hours, in nutrient solution. Seven days after starting the salt treatment the growth of the shoot and root system and the inorganic and organic solutes contents were determined. Salinity reduced the dry matter yield and length of the shoot and root system in both sorghum genotypes, specially in the sensitive one. In general, it was observed an increase in Na+ and Cl- transfer to the shoot, in Na+ and Cl- accumulation and in the Na+/Cl- ratio but a decrease in the K+ and Ca2+ transfer to shoot and in the K+ and Ca2+ contents in the shoot, always with higher intensity in sensitive genotype. Apparently, the tolerance to high saline concentrations in sorghum seems to be related to the genotype ability to avoid accumulation of harmful levels of Na+ and Cl- and, or to maintain adequate levels of K+ and Ca2+, specially in the shoot. The soluble carbohydrates and amino acids constituted together over 98% of the total organic solutes and showed the greatest absolute increase in concentration during saline stress. Probably, the soluble carbohydrates were the most important organic solutes to contribute to the osmotic adjustment in the leaves and the amino acids in the roots. Under saline stress there was an expressive increase in proline contents, specially in the oldest leaves of sensitive genotype. The proline contents, however, even under salt stress, did not reach the levels of other organic solutes. Contrary to the general acceptance, proline does not seem to have an important role in the mechanism of salt tolerance, at least for these genotypes and under the experimental conditions applied here.

Energy nutrients modulate the splanchnic sequestration of dietary nitrogen in humans: a compartmental analysis

2001 ◽  
Vol 281 (2) ◽  
pp. E248-E260 ◽  
Author(s):  
H. Fouillet ◽  
C. Gaudichon ◽  
F. Mariotti ◽  
C. Bos ◽  
J. F. Huneau ◽  
...  
Keyword(s):  
Compartmental Model ◽  
Compartmental Analysis ◽  
Dietary Nitrogen ◽  
Amino Acid Availability ◽  
Nutritional Conditions ◽  
Dietary Amino Acid ◽  
Single Meal ◽  
Peripheral Areas ◽  
Kinetics Of ◽  
Insight Into

We used a previously developed compartmental model to assess the postprandial distribution and metabolism of dietary nitrogen (N) in the splanchnic and peripheral areas after the ingestion of a single meal containing milk protein either alone (MP) or with additional sucrose (SMP) or fat (FMP). The addition of fat was predicted to enhance splanchnic dietary N anabolism only transiently, without significantly affecting the global kinetics of splanchnic retention and peripheral uptake. In contrast, the addition of sucrose, which induced hyperinsulinemia, was predicted to enhance dietary N retention and anabolism in the splanchnic bed, thus leading to reduced peripheral dietary amino acid availability and anabolism. The incorporation of dietary N into splanchnic proteins was thus predicted to reach 18, 24, and 35% of ingested N 8 h after MP, FMP, and SMP, respectively. Such a model provides insight into the dynamics of the system in the nonsteady postprandial state and constitutes a useful, explanatory tool to determine the region-specific utilization of dietary N under different nutritional conditions.

Chrononutrition and Breast Milk: A Review of Circadian Variation in Breast Milk Nutrient Composition

2021 ◽  
Vol 12 (2) ◽  
pp. 74-82
Author(s):  
Gugulethu Moyo ◽  
Shera Jackson ◽  
Allison Childress ◽  
John Dawson ◽  
Leslie Thompson ◽  
...  
Keyword(s):  
Amino Acids ◽  
Breast Milk ◽  
Literature Review ◽  
Current Knowledge ◽  
Circadian Variation ◽  
Small Sample ◽  
Review Of Literature ◽  
Small Sample Sizes

ObjectiveThe objective of this literature review was to identify and summarize the current knowledge on the circadian variation of breast milk nutrients and the implications of these findings.MethodA review of literature was conducted, including all relevant studies regardless of location and year of publication.ResultsThe amino acids tyrosine, histidine, aspartic acid and phenylalanine and energy were observed to be higher during the day. Fat and the vitamins B-1, B-2, B-3, B-6, and B-12 were higher at night. Other studies have shown conflicting results or no circadian variation for certain nutrients. Poor reproducibility and small sample sizes affect the quality of existing research.ConclusionMore research is needed, and longitudinal studies would help assess the effect of breast milk chrononutrition on the long-term health outcomes of infants.

Growth and Maintenance of Dogs Fed Amino Acids as the Source of Dietary Nitrogen

1949 ◽  
Vol 37 (4) ◽  
pp. 429-441 ◽  
Author(s):  
R. H. Silber ◽  
E. E. Howe ◽  
C. C. Porter ◽  
C. W. Mushett
Keyword(s):  
Amino Acids ◽  
Dietary Nitrogen

Studies on the effect of the gut microflora on dietary nitrogen digestibility in pigs

1984 ◽  
Vol 1984 ◽  
pp. 59-59
Author(s):  
B. Ratcliffe ◽  
A.G. Low
Keyword(s):  
Amino Acids ◽  
Preliminary Report ◽  
Gut Microflora ◽  
Reliable Measure ◽  
Germ Free ◽  
Miniature Pigs ◽  
Dietary Nitrogen ◽  
Dietary Amino Acids ◽  
General Recognition ◽  
Dietary Origin

Proteins which escape digestion and absorption in the small intestine of the pig are extensively metabolized by the microbial flora of the large intestine. It is known that bacterial enzymes are potentially capable of catabolizing all amino acids (Michel, 1966). Furthermore, it has been shown that virtually all soluble protein or amino acids introduced into the caecum are rapidly metabolized, absorbed (presumably as ammonia, amines etc.) and the nitrogen (N) derived from them is rapidly excreted as urea (Zebrowska, 1973). This has led to the general recognition that the amino acid composition is not a reliable measure of undigested dietary amino acids in pigs. It has been estimated that only 6% of faecal N is of undigested dietary origin, while the remainder is of bacterial or endogenous origin (Low, Sambrook & Yoshimoto, 1978). It was therefore of interest to estimate which proportions of faecal N derived from a barley-soya diet, are of either bacterial, endogenous or undigested dietary origin. We have used germ-free or conventional miniature pigs for this work because they are small enough to be kept in our isolators for periods of up to 20 weeks. It is emphasised that this is a preliminary report on our first efforts at raising miniature pigs under germ-free conditions.

Effect of free fatty acids on blood amino acid levels in human

1986 ◽  
Vol 250 (6) ◽  
pp. E686-E694 ◽  
Author(s):  
E. Ferrannini ◽  
E. J. Barrett ◽  
S. Bevilacqua ◽  
R. Jacob ◽  
M. Walesky ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Insulin ◽  
Plasma Free Fatty Acid ◽  
Blood Levels ◽  
Experimental Conditions ◽  
Lipid Infusion ◽  
Amino Acid Levels ◽  
Branched Chain

Raised plasma free fatty acid (FFA) levels effectively impede glucose uptake in vivo, thereby conserving plasma glucose and sparing glycogen. To test whether FFA have any effect on blood amino acid levels, we infused Intralipid plus heparin or saline into healthy volunteers under four different experimental conditions: A) overnight fast; B) euglycemic hyperinsulinemia (approximately 100 microU/ml); C) hyperglycemic (approximately 200 mg/100 ml) hyperinsulinemia (approximately 50 microU/ml); and D) hyperglycemic (approximately 300 mg/100 ml) normoinsulinemia (approximately 20 microU/ml). In the fasting state (A), lipid infusion was associated with lower blood levels of most amino acids, both branched chain and glucogenic. This effect, however, could not be ascribed to lipid infusion alone, because plasma insulin levels were also stimulated. The clamp studies (B, C, and D) allowed to assess the influence of lipid on blood amino acid levels at similar plasma insulin and glucose levels. It was thus observed that lipid infusion has a significant hypoaminoacidemic effect of its own under both euglycemic (B) and hyperglycemic (C) conditions; this effect involved many glucogenic amino acids (alanine, glycine, phenylalanine, serine, threonine, and cystine) but none of the branched-chain amino acids (leucine, isoleucine, and valine). In marked contrast, normoinsulinemic hyperglycemia (D), with or without lipid infusion, caused no change in the blood level of any measured amino acid. We conclude that lipid infusion has a hypoaminoacidemic action. We also suggest that this action is permitted by insulin and may involve specific metabolic interactions (e.g., reduced availability of glucose-derived pyruvate or glycerophosphate) as well as enhanced uptake by the liver.

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