Amino Acid Nutrition Research Articles

Changes in Nicotinamide Metabolism by One Amino Acid Deficiency. (I) Threonine-, Tryptophan-, Aspartic Acid-, Lysine-, Leucine-, or Methionine-free Diet.

Effects of a threonine-, tryptophan-, aspartic acid-, lysine-, leucine-, or methionine-free diet fed to rats on the metabolism of nicotinamide were investigated. The body weights of rats and food intakes were greatly decreased by feeding of the diet excluding any of the above essential amino acids compared to the control group, however, not by feeding of an aspartic acid-free diet. The sum of the urinary excretion of nicotinamide, N(1)-methylnicotinamide (MNA), N(1) -methyl-2-pyridone-5-carboxamide (2-Py), and N(1) -methyl-4-pyridone-3-carboxamide (4-Py) changed roughly in proportion to food intake. In the groups fed with the threonine- and lysine-free diets, the urinary excretion of MNA greatly increased compared with the control group during the whole experimental period and in the groups fed with the leucine- and methionine-free diets, increased excretion of MNA was observed on day o-day 1. Whenever the increase in MNA excretion was observed, a decrease in 4-Py excretion was observed. This was attributed to the activity of 4-Py-forming MNA oxidase decreasing when rats were fed with the diet excluding one of the essential amino acid except for tryptophan. Therefore, the (2-Py +4-Py)/MNA excretion was greatly decreased by feeding of the diet excluding one of the essential amino acids except for the tryptophan-free diet. These results strengthened our hypothesis that the (2-Py +4-Py)/MNA excretion reflects the adequacy of amino acid nutrition.

Nutrition — mechanisms of immunosuppression

Nutritionists must formulate diets that supply adequate amounts of nutrients from five major groups. These are carbohydrate, protein (amino acids), fat, minerals and vitamins. Carbohydrate is usually a cheaper source of energy than fat, but fat is often used to increase the caloric concentration of the diet. Variations in energy intake which may effect immunocompetence usually result from management practices rather than diet formulation. Feed restriction for broiler breeders and withholding feed in forced molting practices may affect immunocompetence. Feed restriction causes higher plasma corticosterone levels, which are known to decrease the immune response, possibly through effects on cytokines. Excessive feed, through forced feeding, may also have short-term effects on indicators of humoral immunity. Protein and amino acid nutrition have been studied in relation to immunocompetence. The level of dietary amino acid needed to maximize growth and feed efficiency will also generally maximize measures of immunocompetence. The level of amino acids needed for maximum growth is lower in chicks which have been immunologically stressed than in chicks which have not. An immune response changes metabolism so that less growth occurs, thereby decreasing the need for amino acids. Dietary levels of minerals can affect immunocompetence. While deficient levels of sodium and chloride decrease humoral immunity, levels of these nutrients which supported maximum growth also supported maximal humoral immunity. Low dietary zinc levels did not affect indicators of immunocompetence in the chick. The effect of fat soluble vitamin levels on the immune system has been studied. Vitamin A is needed to maintain epithelial tissue and prevent infection. Cellular immune response is decreased when the chick is deficient in this nutrient. Several indicators of immune responsiveness are depressed when chicks are vitamin E and/or selenium deficient. Since these nutrients serve as antioxidants, cellular integrity may be affected by a deficiency. Cellular integrity is very important for receiving, and responding to the messages needed to coordinate an immune response. High levels of vitamin E (greater than 10 times the required level) have been found to be immunostimulatory.

Soy protein in relation to human protein and amino acid nutrition

The nutritional value of processed soy protein (isolated soy proteins and soy-protein concentrates) in human protein and amino acid nutrition is evaluated on the basis of a review of studies of growth and nitrogen balance in infants, children, adolescents, and adults. Findings show that well-processed soy-protein isolates and soy-protein concentrates can serve as the major, or even sole, source of protein intake and that their protein value is essentially equivalent to that of food proteins of animal origin. The importance of the sulfur amino acid content of soy protein for practical human nutrition is also examined from nitrogen-balance data. Under conditions of an anticipated normal usage of soy protein, methionine supplementation is not only unnecessary but may even be undesirable for young children and adults. However, for newborns, the data suggest that modest supplementation of soy-based formulas with methionine may be beneficial. Soy proteins have also been found to be of good quality to include in hypocaloric diets for weight reduction in obese subjects. Finally, the data indicate that soy proteins are well-tolerated and of good acceptability.

Protein and Amino Acid Nutrition of Lactating Dairy Cattle

This article describes the National Research Council Model of protein metabolism and illustrates its use in meeting the protein requirements of lactating cows. Attention is then directed toward amino acid nutrition with emphasis on the need for models to estimate amino acid requirements. Finally, the potential to improve productivity with rumen-protected amino acids is considered.

Effects of Dietary Protein Degradability and Casein or Amino Acid Infusions on Production and Plasma Amino Acids in Dairy Cows

Responses to daily abomasal infusions of 400g sodium caseinate, 400g hydrolyzed casein, or 11.3g L-methionine plus 30.1g L-lysine were compared in eight Holstein cows fed diets with estimated ruminal protein degradabilities of 70 and 60.5%. Basal diets contained corn silage and corn with either soybean meal or 66.7:33.3 soybean meal:corn gluten meal added. Infusion with Methionine plus lysine increased milk protein content when cows were fed either diet but increased milk fat content and yield only when the soybean meal diet was fed. Sodium caseinate increased milk and milk protein production and decreased milk fat percentage. Concentration of total essential amino acids, branched chain amino acids, and urea cycle amino acids were increased by the infusion of both casein sources. Methionine-lysine infusion increased plasma lysine and taurine, a metabolite of methionine, suggesting that absorbed methionine was extensively metabolized. Results demonstrate an impact of both ruminal degradability of dietary protein and form of infused protein on amino acid nutrition of lactaring dairy cows.

A review of the role of acid-base balance in amino acid nutrition.

Acid-base balance and amino acid metabolism are intimately related. Changes in acid-base balance influence the metabolic fate of many amino acids. Also, acid-base homeostasis is achieved in part by alteration of amino acid metabolism, not only in the kidney, but also in liver, muscle and splanchnic tissue. Glutamine is the primary amino acid involved in renal ammonia-genesis, a process intimately related to acid excretion. The metabolism of other amino acids, such a serine, glycine and the branched-chain amino acids, also appears to be influenced by acid-base balance. Conversely, the metabolic fate of various amino acids will influence the daily acid load experienced by the animal. Oxidation of amino acids contributes to the total acid and base load imposed on the pig. The basic (cationic) amino acids (lysine, arginine and histidine) yield neutral end-products plus a proton; sulfur (methionine and cysteine) amino acids are also acidogenic because they generate sulfuric acid when oxidized. The dicarboxylic (anionic) amino acids (aspartate and glutamate, but not asparagine and glutamine) consume acid when oxidized and thus reduce the acid load of the diet. Acid-base balance and related phenomena are discussed in the context of practical and metabolic aspects of amino acid nutrition.

Maintenance of Small Bowel Mucosa with Glutamine‐Enriched Parenteral Nutrition

Glutamine is an important fuel utilized by the intestinal mucosa that is not present in standard amino acid nutrition solutions. In order to determine the effects of glutamine on the intestine, glutamine enriched nutrition was administered intravenously to male Wistar rats. A standard amino acid solution was enriched with 1 and 2 g/100 ml of glutamine or glycine and used as part of a parenteral nutrition regime for 7 days. Intestinal samples were taken for measurements of jejunal weight, DNA, protein, mucosal thickness and villus height. Animals receiving 2 g glutamine/100 ml in the nutrition solution had increased intestinal weight, DNA, and villus height when compared to animals receiving 2 g/100 ml of glycine. No increase in the intestinal parameters was noted when 1 g/100 ml of glutamine was used. To investigate the dose-response effects of glutamine, further studies were performed using isonitrogenous and isocaloric solutions containing 0, 2, and 3 g of glutamine/100 ml. Animals receiving glutamine had a significant increase in mucosal weight, DNA, protein and villus height when compared to animals receiving no glutamine in the parenteral solutions. There was a dose-response relationship between the increase in jejunal DNA and the increased intake of glutamine (r = 0.93, p less than 0.01) but no correlation with the nitrogen content of the solutions (r = 0.18, p = 0.8). Total body nitrogen retention was greater in animals receiving 2 g/100 ml of glutamine (166 +/- 12 mg, days 6/7) when compared to those receiving 0 and 3 g of glutamine/100 ml (126 +/- 14 mg and 138 +/- 16 mg, respectively, p less than 0.05). These studies demonstrate that glutamine enriched nutrition protects against atrophy of the intestinal mucosa and when given at 2 g/100 ml improves nitrogen retention during intravenous feeding.

含硫アミノ酸とくにシステインの代謝と栄養

含硫アミノ酸とくにシステインの代謝と栄養

Effects of methionine and other sulfur compounds on drug conjugations

Conjugation reactions in the detoxification of drugs and environmental chemicals occur with various sulfur-containing substances. These reactions include: (1) glutathione (GSH, reduced glutathione) conjugation with subsequent mercapturic acid synthesis; (2) sulfate conjugation (sulfate ester synthesis); (3) methylation by S-adenosylmethionine (SAM); (4) thiosulfate conjugation of the cyanide ion, resulting in thiocyanate synthesis; (5) chelation of toxic metals by metallothionein, a sulfhydryl-rich protein. Of the drug conjugation reactions affected by methionine and cysteine intake and metabolism, sulfate and glutathione reactions have the greatest physiological significance. Much study has been devoted to the determination of intraand extracellular concentrations and transport of sulfur-containing compounds, and their relation to xenobiotic metabolism. Studies of the influence of dietary sulfur amino acid intake on the utilization during xenobiotic metabolism of sulfur-containing compounds are more limited, however. This review describes these studies as they relate to sulfur amino acid nutrition and Phase II drug conjugations. The major focus is on the effect of dietary methionine and cysteine intake on sulfate and glutathione conjugation reactions.

Whole-body amino acid composition and comparative aspects of amino acid nutrition of the goldfish, golden shiner and fathead minnow

Pond-raised fingerling goldfish ( Carassius auratus), golden shiners ( Notemigonus crysoleucas) and fathead minnows ( Pimephales promelas) were analyzed for whole-body amino acid composition. All three species had similar amino acid patterns in whole-body tissue. These compositional data were also used to compute essential amino acid ratios ( A E ratios) which were compared with the quantified amino acid requirements of another cyprinid species, the common carp ( Cyprinus carpio). The whole-body A E ratios of the three baitfish species were very similar to the A E ratios of the carp requirement values. Since previous studies have established a high correlation between whole-body amino acid patterns and dietary amino acid requirement patterns of several fish species, the whole-body amino acid values determined in this study will provide indices for formulating diets for the goldfish, golden shiner and fathead minnow.

Federal regulation of drugs administered through feed

It is a pleasure for me to be part of this program on nutrition and nutritional diseases in food animals. Although my formal education was in animal nutrition, it has been very difficult to keep up with new advances. In fact, it has been difficult to maintain a working knowledge in amino acid nutrition, an area I spent many years researching. Therefore, I intend to listen attentively to what is said by others from this podium.

Maintenance of skeletal muscle intracellular glutamine during standard surgical trauma.

Skeletal muscle glutamine (GLN) concentration falls following injury and infection. In an attempt to prevent this decline and to characterize its influence on the efflux of amino acid (AA) from skeletal muscle, we administered varying quantities of AA (0,2, and 4 g/kg X day) as saline or AA solutions with or without GLN enrichment to 22 postoperative dogs. Plasma and muscle AA were determined before and 24 hr after standard laparotomy. Hindquarter AA efflux was measured at 6 and 24 hr. Skeletal muscle nitrogen declined in saline controls (69.8 +/- 8.5 vs 52.8 +/- 8.4 mmol/liter; p less than 0.01), largely due to the fall in intracellular GLN (21.48 +/- 3.21 vs 15.86 +/- 3.80; p less than 0.05). Similar alterations were seen in the animals receiving 2 g/kg. However, both intracellular nitrogen and GLN were maintained in animals receiving 4 g/kg, whether the AA solutions contained GLN or not (skeletal muscle nitrogen before 64.3 +/- 8.6 mmol/l vs 65.4 +/- 7.0 after, GLN 19.2 +/- 3.4 vs 19.9 +/- 3.0). Hindquarter AA efflux was reduced in those animals at 6 hr compared with saline-treated animals (-6.52 +/- 1.8 and -7.70 +/- 5.90 vs -19.05 +/- 4.06 mumol/kg X min; p less than 0.05). Intracellular GLN can be maintained during operative stress with adequate nitrogen infusion. Replacing 50% of the balanced AA solution with GLN resulted in equally effective maintenance of intracellular GLN levels and a comparable reduction in skeletal muscle AA efflux. Preservation of normal intracellular GLN levels with adequate AA nutrition may be essential for the conservation of muscle protein.

Sulfur amino acid nutrition of the growing puppy: Determination of dietary requirements for methionine and cystine

English Pointer puppies were fed a crystalline amino acid diet (4002 kcal ME/kg) in a series of six experiments to determine the total sulfur amino acid (SAA) requirement and optimal cystinemethionine ratio for maximal rate and efficiency of weight gain. In experiments 1 and 2, equal-weight portions of cystine and methionine were fed at levels ranging from 0.25 to 0.65% of the diet. Rate of gain and feed conversion efficiency were maximized when SAA comprised 0.45% of the diet (112.4 mg SAA/100 kcal ME). The portion of the SAA requirement contributable by cystine was determined in experiments 3 and 4 to be 50% on a weight basis (55% on a molar basis). When a basal diet containing 0.1125% methionine (50% of the methionine requirement) and 0.1125% cystine was supplemented with an additional 0.225% cystine (cystine comprising 75% of SAA on a weight basis), reduced growth and skin lesions on the front paw and pad developed. A pair-feeding study established that the adverse effects of excess cystine were characteristic of an amino acid imbalance rather than an antagonism. Thus, excess cystine superimposed on a methionine deficiency reduced voluntary food (and methionine) intake which in large measure explained the growth depression and paw dermatitis.

タウリンを中心とした含硫アミノ酸の代謝と栄養

タウリンを中心とした含硫アミノ酸の代謝と栄養

The effect of branched chain enriched amino acid nutrition on the outcome of acute hepatic coma in cirrhosis : [formula omitted], A. Dejgård, C. Gluud, M. Kristensen, O. Køhler, B. Melgaard, H.J. Schütten, H. Vilstrup and the Copenhagen Coma Group. (Centralsygehuset, Hillerød, Hvidovre Hospital, Bispebjerg Hospital and Rigshospitalet, University of Copenhage, Denmark)

The effect of branched chain enriched amino acid nutrition on the outcome of acute hepatic coma in cirrhosis : [formula omitted], A. Dejgård, C. Gluud, M. Kristensen, O. Køhler, B. Melgaard, H.J. Schütten, H. Vilstrup and the Copenhagen Coma Group. (Centralsygehuset, Hillerød, Hvidovre Hospital, Bispebjerg Hospital and Rigshospitalet, University of Copenhage, Denmark)

Branched chain enriched amino acid nutrition does not change the outcome of hepatic coma in patients with cirrhosis of the liver

Branched chain enriched amino acid nutrition does not change the outcome of hepatic coma in patients with cirrhosis of the liver

Sulfur Amino Acid Nutrition during Molt in the White-Crowned Sparrow. 1. Does Dietary Sulfur Amino Acid Concentration Affect the Energetics of Molt as Assayed by Metabolized Energy?

To test the hypothesis that the dietary intake of the sulfur-con- taining amino acids (SAA) methionine and cyst(e)ine affects energy intake or the allocation of energy to production and oxidation, respectively, we fed five groups of White-crowned Sparrows (Zonotrichia leucophrys gambelii) five isocaloric, isonitrogenous diets before, during, and after their postnuptial molt. The diets ranged in SAA content from sub- to superadequate in relation to standards es- tablished for poultry, and from very low to very high in relation to the SAA content of natural foods. The patterns of plumage replacement were indistin- guishable among the five groups. The body weights of all birds decreased sharply at the onset of molt, as is typical for this and other species, and then gradually increased through early molt and stabilized during mid- and late molt. The com- ponents of energy balance (gross energy intake, energy utilization coefficient, ca- loric density of excreta, total excretory energy output) did not differ significantly or consistently among the five groups. Likewise, the net energy of molt, as esti- mated by subtracting the maintenance requirement for metabolized energy from the expenditure during molt by the same birds, ranged from 582 to 611 kJ, but without significant differences among the groups and without consistent corre- lations to the diets. The grand average was 605 kJ/25-g bird. Hence, we are unable to verify the predictions of the amino acid model for the determination of the energy requirements of molt.

Sulfur Amino Acid Nutrition during Molt in the White-Crowned Sparrow. 2. Nitrogen and Sulfur Balance in Birds Fed Graded Levels of the Sulfur-Containing Amino Acids

-In an effort to estimate a critical concentration of dietary sulfurcontaining amino acids (SAA) for molting birds, we measured nitrogen (N) and sulfur (S) balances before, during, and after postnuptial molt in five groups of White-crowned Sparrows (Zonotrichia leucophrys gambelii) fed isocaloric and isonitrogenous (17.4 kJ/g and 13.5% protein) diets in which SAA concentration ranged from 0.33 to 0.78%. These SAA concentrations approximate those found in natural diets and, as well, bracket the SAA requirements of poultry. Birds from all dietary groups showed positive N and S balances through six temporally equal stages of molt and in the nonmolting periods. Nitrogen retention differed significantly among molt stages but not among dietary groups. The grand average net N retention during molt (total N retention minus basal N retention) was 623 mg/ 25-g bird. Sulfur retention differed significantly among stages and among dietary groups. However, because group differences occurred both during molt and in nonmolt, the net S retention during molt (total S retention minus basal S retention) did not differ significantly among dietary groups. The grand average net S retention during molt was 85.4 mg/25-g bird. These results indicate that molting Whitecrowned Sparrows are typically able to meet the protein and SAA demands of molt through their food (the critical dietary SAA concentrations being less than those likely to be found in natural diets), thus precluding the need to deplete tissue proteins. Avian molt is a type of growth characterized primarily by protein accretion in the form of feathers, and secondarily by the regeneration of other epidermal structures (Spearman 1966, Payne 1972, Chilgren 1975). Despite its morphological restriction, this integumental growth can entail a deposition of a protein mass approaching, or even exceeding, one-fourth of the protein content of a bird's body (Mitchell et al. 1931, Newton 1968, Myrcha and Pinowski 1970, Gavrilov and Dolnik 1974, Chilgren 1977, Carey et al. 1978). Moreover, the cyst(e)ine content of the plumage is disproportionately large compared to its content in the mixed proteins of other tissues or foods (Nitsan et al. 1981, Murphy and King 1982a; cf. F.A.O. 1970, Scott et al. 1982). These observations have, for decades, led avian biologists to question the ability of birds to fulfill the protein demands, or more specifically the sulfur amino acid (SAA) demands, of molt through daily food intake alone. The availability of dietary SAA has often been invoked as a potential explanation for observed changes in body composition, feeding habits, or even energetics during molt (e.g., Hanson 1962, Newton 1968, Gavrilov and Dolnik 1974, Brake et al. 1979), on the assumptions that (1) endogenous SAA reserves will be used if exogenous sources are inadequate, (2) birds may choose foods on the basis of SAA content, or (3) food intake may be increased above caloric needs to fulfill SAA requirements. The results of the few empirical investigations that have been conducted on these subjects thus far are equivocal. Ackerson and Blish (1926) reported a disproportionate nitrogensparing effect of supplemental cystine in molting domestic fowl (Gallus gallus var. domesticus) that were fed otherwise N-free diets. Subsequent experiments (Ackerson et al. 1928) using a corn/casein diet and cystine supplements, however, failed to show a beneficial effect of these supplements on body weight, egg production, or the dynamics of molt in fowl. Similar investigations involving a laying ration and methionine supplementation also were ineffective in shortening the molting period or in increasing post-molt egg production in fowl (Taylor and Russell 1943). Likewise,

Interorgan amino acid nutrition.

I should emphasize that by Interorgan Amino Acid Nutrition I mean rather more than the partition of exogenous nutrients among the various tissues, more than a mass-action sharing from the alimentary flow somewhat analogous perhaps to that by a litter of pigs feeding at a common trough. As an example, glutamine, as the reader has already seen, is a vital interorgan nutrient, even when by chance none is being received from an exogenous source. To protect its functional needs, the liver might be said to recycle and partition the glutamine it receives and forms by governing how much it consumes and how much it generates. But these effects are achieved by compartmentalizing these actions, as Haussinger (1987) has shown, by making the first “decision” with regard to NH4 + detoxication by ureogenesis in the periportal hepatocytes and the second decision by glutamine synthesis in the perivenous hepatocytes. Although this sequence may appear to be a purely hepatic “decision”, note that it allows the liver to allot its glutamine to nourish other organs while protecting its own needs. It seems inevitable that the resulting sequence occasions interacinar flows of glutamine and glutamate, and probably of other amino acids, for which flows must depend upon the presence of and may be regulated by the capacity and the activity of the pertinent amino acid transport systems.

Amino acid nutrition and yeast-mycelial dimorphism in Aureobasidium pullulans

Amino acid nutrition and yeast-mycelial dimorphism in Aureobasidium pullulans