Do the Differences between the Amino Acid Compositions of Acute-Phase and Muscle Proteins Have a Bearing on Nitrogen Loss in Traumatic States?

Reeds, Peter J.; Fjeld, Carla R.; Jahoor, Farook

doi:10.1093/jn/124.6.906

Cited by 300 publications

(235 citation statements)

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“…On the basis of the AA composition of acute-phase proteins and their increased synthesis by the liver during infection it has been hypothesised that demand for phenylalanine would increase (14) . Such increased demands may be counteracted by less production of serum albumin, as occurs in response to reduced intake (31) or certain infections (32) , although this can vary with stage of infection (33) .…”

Section: Discussionmentioning

confidence: 99%

“…From 12 h onwards a mixture of stable isotope-labelled AA was infused into all animals as described previously (18) . Briefly, 1 g [U- 13 C]whole algal hydrolysate prepared from Celtone-C (Martek Biosciences Corporation), plus 100 mg L-[5-13 C]methyl methionine 100 mg, 120 mg L-[1-13 C]cysteine and 150 mg L- [2][3][4][5][6][7][8][9][10][11][12][13][14][15] N]glutamine (all sourced from Cambridge Isotope Laboratories), was dissolved in 100 ml of buffered physiological saline (pH 7·4) containing 50 000 IU of heparin and infused at 10 g/h. Methionine, cysteine and glutamine were added, as these AA are lost during the acid hydrolysis preparation of the whole algal powder.…”

Section: Main Studymentioning

confidence: 99%

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Responses in whole-body amino acid kinetics to an acute, sub-clinical endotoxin challenge in lambs

et al. 2015

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Some effects of parasitism, endotoxaemia or sepsis can be mitigated by provision of extra protein. Supplemented protein may encompass a metabolic requirement for specific amino acids (AA). The current study investigates a method to identify and quantify the amounts of AA required during inflammation induced by an endotoxin challenge. One of each pair of six twin sheep was infused in the jugular vein for 20 h with either saline (control) or lipopolysaccharide (LPS, 2 ng/kg body weight per min) from Escherichia coli. Between 12 and 20 h a mixture of stable isotope-labelled AA was infused to measure irreversible loss rates. From 16 to 20 h all sheep were supplemented with a mixture of unlabelled AA infused intravenously. Blood samples were taken before the start of infusions, and then continuously over intervals between 14 and 20 h. At 20 h the sheep were euthanised, and liver and kidney samples were taken for measurement of serine-threonine dehydratase (SDH) activity. LPS infusion decreased plasma concentrations of most AA (P < 0·05; P < 0·10 for leucine and tryptophan), except for phenylalanine (which increased P = 0·022) and tyrosine. On the basis of the incremental response to the supplemental AA, arginine, aspartate, cysteine, glutamate, lysine (tendency only), glycine, methionine, proline, serine and threonine were important in the metabolic response to the endotoxaemia. The AA infusion between 16 and 20 h restored the plasma concentrations in the LPS-treated sheep for the majority of AA, except for glutamine, isoleucine, methionine, serine and valine. LPS treatment increased (P < 0·02) SDH activity in both liver and kidney. The approach allows quantification of key AA required during challenge situations.Key words: Endotoxin lipopolysaccharide: Amino acids: Irreversible loss rate: Serine-threonine dehydratase: SheepThe protein and amino acid (AA) demands of animals for normal physiological states (e.g. growth, pregnancy and lactation) are now well characterised, especially for pigs and poultry (1) and with progress made in ruminants (2) . These requirements are altered, however, in response to injury, infection and parasitic challenge. In many cases, impact of these challenges can be ameliorated and the rate of recovery improved by provision of additional protein in the diet (3)(4)(5)(6) . Often, however, the amount of protein required is not known, with consequences for both animal performance and farm economics.More importantly, protein per se may not be required, but instead the metabolic responses to the challenge may increase the demand for specific AA. For example, practical and theoretical arguments have been presented for additional arginine in cardiovascular and pulmonary disorders (7)(8)(9)(10) , for cysteine (11) , leucine (12) and threonine (13) in sepsis, for glutamine in endotoxaemia (10) , and for phenylalanine to support acutephase protein synthesis (14) . In other situations, combinations of AA have been proposed (10,15,16) . Obviously different stages of injury, infection or recover...

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Section: Discussionmentioning

confidence: 99%

Section: Main Studymentioning

confidence: 99%

Responses in whole-body amino acid kinetics to an acute, sub-clinical endotoxin challenge in lambs

et al. 2015

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“…In addition to its role in movement and posture, regulation of metabolism, and storage of energy and nitrogen, skeletal muscle becomes a vital supplier of amino acids to be used as a fuel by the brain and immune system, and as a substrate for wound healing during malnutrition, starvation, injury and disease [3]. The maintenance of body protein mass is critical not only to remain physically independent, but also for survival.…”

Section: Introductionmentioning

confidence: 99%

Amino acid metabolism and regulatory effects in aging

Timmerman

Volpi²

2008

Current Opinion in Clinical Nutrition and Metabolic Care

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Purpose of review-To examine recent discoveries related to the amino acid metabolism and regulatory effects in aging, focusing on the development and treatment of age-related muscle loss (sarcopenia).Recent findings-While basal amino acid metabolism may be unaffected by age, elderly subjects appear to have a decreased ability to respond to anabolic stimuli such as insulin and, to a lesser extent, amino acids. Specifically, compared to young subjects, the stimulation of muscle protein synthesis is attenuated in elderly subjects following the administration of mixed meals due to insulin resistance. In addition, the anabolic effect of amino acids appears blunted at low doses. Recent studies, however, have highlighted that these age-related alterations in amino acid metabolism may be overcome by provision of excess leucine, changes in the daily protein intake pattern or exercise, which improve activation of translation initiation and muscle protein synthesis.Summary-Muscle loss with aging is associated with significant changes in amino acid metabolism, which can be acutely reversed using nutritional manipulations and exercise. Longterm, large clinical trials are, however, needed to determine the clinical significance of these findings in the elderly population, and to establish if nutritional and exercise interventions can help prevent and treat sarcopenia.

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“…ageing, infection). Indeed, due to the differences between the amino acid composition of Nutrients for production and product quality acute-phase and muscle proteins, a considerable amount of muscle protein must be degraded to provide the amino acids used in the acute-phase response (Reeds et al, 1994). Understanding the mechanisms by which amino acids regulate protein metabolism is therefore essential to improve control of the use of nutrients and optimise dietary amino acid supply.…”

Section: Effect Of the Nature Of Nutrientsmentioning

confidence: 99%

Responses to nutrients in farm animals: implications for production and quality

Hocquette

Tesseraud

Cassar-Malek

et al. 2007

Animal

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It is well known that any quantitative (energy and protein levels) and qualitative (nature of the diet, nutrient dynamic) changes in the feeding of animals affect metabolism. Energy expenditure and feed efficiency at the whole-body level, nutrient partitioning between and within tissues and organs and, ultimately, tissue and organ characteristics are the major regulated traits with consequences on the quality of the meat and milk produced. Recent progress in biology has brought to light important biological mechanisms which explain these observations: for instance, regulation by the nutrients of gene expression or of key metabolic enzyme activity, interaction and sometimes cross-regulation or competition between nutrients to provide free energy (ATP) to living cells, indirect action of nutrients through a complex hormonal action, and, particularly in herbivores, interactions between trans-fatty acids produced in the rumen and tissue metabolism. One of the main targets of this nutritional regulation is a modification of tissue insulin sensitivity and hence of insulin action. In addition, the nutritional control of mitochondrial activity (and hence of nutrient catabolism) is another major mechanism by which nutrients may affect body composition and tissue characteristics. These regulations are of great importance in the most metabolically active tissues (the digestive tract and the liver) and may have undesirable (i.e. diabetes and obesity in humans) or desirable consequences (such as the production of fatty liver by ducks and geese, and the production of fatty and hence tasty meat or milk with an adapted fatty acid profile).

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Do the Differences between the Amino Acid Compositions of Acute-Phase and Muscle Proteins Have a Bearing on Nitrogen Loss in Traumatic States?

Cited by 300 publications

References 23 publications

Responses in whole-body amino acid kinetics to an acute, sub-clinical endotoxin challenge in lambs

Responses in whole-body amino acid kinetics to an acute, sub-clinical endotoxin challenge in lambs

Amino acid metabolism and regulatory effects in aging

Responses to nutrients in farm animals: implications for production and quality

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