Complete Amino Acid Diet Research Articles

Safety of Anti-Tumor Necrosis Factor Agents in Rheumatic Potential Carriers of Occult Hepatitis B Virus: Table 1.

<h3>Background</h3> Leucine (Leu) plays an important role in the enterocyte. Our previous study showed that fecal concentration of Leu was decreased after mucosal healing (MH) of UC, but the mechanism of Leu in MH remains unknown. <h3>Methods</h3> The receiver operator characteristic curve was plotted to evaluate the value of Leu in predicting MH, combined with Fecal calprotectin (FC). A dextran sulfate sodium-induced colitis model was established by feeding a leucine-deficient and complete amino acid diet to explore the role of Leu in the intestinal barrier. Cell proliferation, migration, apoptosis and the expressions of NF-κB, TJ and mTORC1signal proteins were detected in Caco-2 cultured by deficient and 250μmol/L Leu. <h3>Results</h3> 1. Fecal concentration of Leu was positively correlated with FC, R=0.831. The AUC of Leu in predicting of MH was 0.9289, and the sensitivity and specificity were 86.7% and 93.3% when the cut-off value was 347.35μg/g. 2. The biosynthesis of Leu was enriched in MH, related to Bacteroidetes, Ruminococcus, Eubacterium, Alistipes and Faecalibacterium prausnitzii. 3. The expression of Claudin-4, Occludin and ZO-1 decreased in mice fed a Leu-deficient diet, and increased after supplementation of Leu. The inflammation exhibited the opposite effect. 4. In Leu deficient cells, the proliferation and migration activity decreased, accompanied by a little apoptosis. The expressions of TLR4, MyD88, and p-P65 were increased, while Claudin-4, Occludin, ZO-1, p-mTORC1, p-S6K and p-4E-BP1 decreased. The changes were more pronounced after LPS. Inhibited mTORC1, proliferation and migration activity of cells decreased, apoptosis and the expressions of TLR4, MyD88, and p-P65 were increased, while the expressions of Claudin-4, Occludin, ZO-1, p-S6K and p-4E-BP1 were decreased. <h3>Conclusions</h3> 1. Leu had high sensitivity and specificity in predicting MH, and had the potential to become a novel adjuvant biomarker for MH. 2. The biosynthesis of Leu was enriched in MH, which may affect the gut microbiota, and participated in intestinal epithelial metabolism to promote MH. 3. Leu promoted cell proliferation, migration, and anti-apoptosis, inhibited NF-κB pathway to anti-inflammatory and stimulated protein synthesis to enhance intestinal barrier function by activating mTORC1 signaling pathway, participated in MH.

Is putrescine an essential nutrient for avians?

Putrescine addition to a complete crystalline amino acid diet elicited a growth response in young chicks, suggesting that putrescine may be an essential nutrient in avians. However, high dietary putrescine levels can depress weight gain.

Adaptation to a long term (4 weeks) arginine- and precursor (glutamate, proline and aspartate)-free diet

It is not known whether arginine homeostasis is negatively affected by a "long term" dietary restriction of arginine and its major precursors in healthy adults. To assess the effects of a 4-week arginine- and precursor-free dietary intake on the regulatory mechanisms of arginine homeostasis in healthy subjects. Ten healthy adults received a complete amino acid diet for 1 week (control diet) and following a break period, six subjects received a 4-week arginine, proline, glutamate and aspartate-free diet (APF diet). The other four subjects continued for 4 weeks with the complete diet. On days 4 and 7 of the first week and days 25 and 28 of the 4-week period, the subjects received 24-h infusions of arginine, citrulline, leucine and urea tracers. During the 4-week APF, plasma arginine fluxes for the fed state, were significantly reduced. There were no significant differences for citrulline, leucine or urea fluxes. Arginine de novo synthesis was not affected by the APF intake. However, arginine oxidation was significantly decreased. In healthy adults, homeostasis of arginine under a long term arginine- and precursor-free intake is achieved by decreasing catabolic rates, while de novo arginine synthesis is maintained.

Plasma proline kinetics and concentrations in young men in response to dietary proline deprivation

This study examined plasma proline concentration flux, oxidation, and endogenous biosynthesis in five healthy young men given three isocaloric, isonitrogenous diets for 1 wk [a complete egg-pattern amino acid diet (diet 1), an amino acid mixture devoid of proline (diet 2), and a diet composed solely of indispensable amino acids (diet 3)]. At the end of each dietary period, a 360-min postabsorptive, primed, continuous stable-isotope-tracer infusion of L-[1-13C]proline and L-[methyl-2H3]leucine was performed in all subjects. Plasma proline concentrations declined by 22% on diet 2 (p less than 0.02) and by 29% on diet 3 (p less than 0.01). No statistically significant (p greater than 0.2) changes were observed for proline oxidation, endogenous biosynthesis, or flux. The data suggest that the absence of proline in the human diet does not trigger changes in proline dynamics during the postabsorptive state. The metabolic significance of the reduction of plasma proline concentrations requires elucidation.

Histidine deficiency, food intake and growth in normal and Walker 256 carcinosarcoma-bearing rats.

Male Sprague-Dawley rats with and without growing Walker 256 tumors were fed 3 isonitrogenous, isoenergetic, semisynthetic diets. The N sources of the 3 diets were casein, a complete free amino acid mixture simulating casein, and the same amino acid mixture but now totally lacking histidine. Tumor-free rats and host and tumor components of tumor-bearing rats showed identical growth on the casein and on the casein-simulating free amino acid diets. Change from complete amino acid diet to histidine-free diet depressed food intake identically in controls and tumor-bearers in early stages of tumor growth. In later stages of tumor growth, when tumor-induced hypophagia had become apparent on the complete diet, the histidine-free diet had a progressively less depressive effect on food intake in the tumor-bearers.

Effect of Dietary Amino Acids on Jejunal Sucrase and Leucineaminopeptidase Activities in Rats

The effect of dietary amino acids on jejunal sucrase (EC 3.2.1.26) and leucineaminopeptidase (EC 3.4.11.1, LAPase) activities in rats was studied. Rats were force-fed a 10% complete amino acid diet or valine-free diet. The sucrase and LAPase activities in rats force-fed the valine-free diet for 2 days were significantly lower than those in rats force-fed the complete amino acid diet, although the specific activities of these enzymes in the isolated brush border fragment were 10 times higher than those in the mucosa, and most of the activities of these enzymes in the mucosa were localized in the isolated brush border fragment. Results of experiments undertaken to investigate the effects of dietary amino acids during the initial period after the dietary alteration on the sucrase and LAPase activities showed that decreases in the activities of these enzymes in rats force-fed the valine-free diet appeared by 26 hours after the first feed administration; whereas, incorporation of dietary 14C-amino acids administered in the first feed administration into the mucosal protein was significantly lower in rats receiving the valine-free diet than in rats receiving the complete amino acid diet by 7 hours following the first feed administration. These results suggest that decreases in availability of dietary amino acids in the valine-free diet for protein formation in the small intestinal mucosa during the initial period caused the decreases in the sucrase and LAPase activities localized in the brush border membrane.

461 ROLE OF DIETARY PROTEIN AND AMINO ACIDS IN THE MODULATION OF PLASMA SOMATOMEDIN ACTIVITY IN RATS

The mechanism of growth retardation in many nutritional deficiency states has not been delineated. Somatomedin (SM) is depressed after prolonged fasting or in severe malnutrition despite elevated growth hormone (GH) concentrations, suggesting both nutrition and GH may act as modulators of SM. We have studied the effects of varying concentrations of dietary protein (2.5, 5, 10, 20%) and specific dietary amino acid deficiencies on body and organ weights, GH, SM, cartilage glycosaminoglycans (GAGS) and biochemical composition of brain and liver. Changes in body weights and organ weights were similar for 2.5% protein, a valine deficient or a tryptophane deficient diet (-10%). An increase of 177% was observed for animals on a complete amino acid diet or a 20% protein diet. Arginine deficiency had an intermediate effect. Biochemical alterations were more striking in liver than in brain. Serum SM ranged from 0.20 units for rats on the valine and tryptophane deficient diet to 1.44 units for the rats on the complete diet. SM was positively correlated with the protein content of the diet, body and organ weight changes, food efficiency and cartilage GAGS content and negatively correlated with GH concentrations. These data suggest that dietary protein and amino acids play a direct role in the modulation of SM activity and the growth retardation associated with some nutritional deficiency states may be related to its additional effect on SM activity.

Ammonia intoxication in the near-adult cat as a result of a dietary deficiency of arginine.

Near-adult cats, fasted overnight, and given a single meal of a complete amino acid diet without arginine, developed hyperammonemia and showed clinical symptoms of ammonia toxicity within 2 hours. One cat (2.7 kilograms) died 4.5 hours after ingesting only 8 grams of the diet. Since ornithine also prevented hyperammonemia, it appears that the domestic cat cannot synthesize ornithine.

Effect of Force-feeding a Valine-free Diet on Gastrointestinal Function of Rats

To study the effect of an essential amino acid deficiency on gastrointestinal functions, rats were force-fed a 10% amino acid diet devoid of valine for several days, and subsequently a complete amino acid diet. Force-feeding of the valine-free diet for a few days delayed the disappearance of dietary nitrogen from the gastrointestinal tract. ASINGLE FEEDING OF THE COMPLETE AMINO ACID DIET CONTAINING 14C-labeled amino acids or (14C)glucose to rats previously fed the valine-free diet did not improve disappearance of the nitrogen. The absorption of the dietary carbohydrate as well as dietary nitrogen was delayed after feeding the valine-free diet. In spite of the delayed disappearance of dietary 14C-labeled amino acids or (14C)glucose from the gastrointestinal tract, the incorporation of these dietary 14C-labeled amino acids into liver lipids was not different between rats fed the complete amino acid diet and those fed the valine-free diet. Under these experimental conditions, changes in disaccharidase activities in the intestinal mucosa were in parallel with changes in the disappearance of nutrients from the gastrointestinal tract.

Body Composition and Protein Utilization of Chicks Fed Graded Levels of Fat

Two experiments involving chicks fed a complete crystalline amino acid diet from day 8 to day 21 posthatching were employed to evaluate body composition changes and protein utilization as a function of dietary caloric density. In experiment 1 graded levels of corn oil from 5 to 25% of the diet were fed. Chicks gained as rapidly and utilized the dietary nitrogen as efficiently when 5% corn oil was fed as when higher levels were fed. As caloric density of the diet increased, chicks ate to meet their energy need and therefore cut back on feed (hence, protein) intake. Nonetheless, each increment of protein intake was used at the same efficiency. Body fat increased and body protein decreased with each incremental increase in dietary corn oil. In experiment 2 it was established that protein utilization remained constant over a wide range of protein intake (below the requirement for maximal protein retention), regardless of whether protein intake differences resulted from a change in caloric density of the diet or from a change in the dietary concentration of the complete amino acid mixture. Energy retention appeared to reach a maxima at a dietary concentration of 15% corn oil or 4.19 kcal. M.E./g.

Plasma amino acid curve in rats force-fed a single meal lacking an essential amino acid

The amino acid levels in plasma and liver were determined in rats at various time intervals after giving the animals a single meal of a complete amino acid diet (CAA) or a diet devoid of either leucine, isoleucine, or threonine. Male rats were fed by stomach tube and they were killed at 0, 2, 4, 6, or 8 hours postprandial. Amino acid analyses were performed on deproteinized supernatants of plasma and liver. The changes in the plasma amino acid levels occurred within 2 hr after feeding a single meal of either the diet lacking leucine or CAA. The values of most of the amino acids attained their highest levels at 4 hr postprandial and many amino acids were declining in concentration at 6 and 8 hr. Isoleucine and valine showed very high levels in plasma at 2, 4, 6 and 8 hr after feeding the diet devoid of leucine. The amino acid levels in liver reflected the amino acid concentrations in plasma at each time interval. Rats fed the diets devoid of either isoleucine or threonine demonstrated less alterations in plasma amino acid concentrations with only a few amino acids changed. After giving a single meal the amino acid levels in plasma are transient since many of the amino acids show similar values at the 0- and 8-hr intervals. The alterations in amino acid levels in plasma that occur after feeding are dependent upon both the identity of the essential amino acid omitted from the diet and the postprandial time.

ウナギの必須アミノ酸

Essential amino acids for the 2 species of eel, A. anguilla and A. japonica, were examined by using an amino acid test diet. Forty fish were grouped in each aquarium and fed the test diets for a period of 6 weeks. In the both species, the fish fed diets deficient in each of alanine, aspartic acid, cystine, glutamic acid, glycine, proline, and tyrosine grew as well as those fed the complete amino acid diet. The fish fed diets deficient in each of arginine, histidine, isoleucine, leucine, lysine. methionine, phenylalanine, threonine, tryptophan, and valine failed to grow until the deleted amino acid was added to the ration. It was thus established that eels require the same 10 kinds of amino acid reported to be essential for salmonids and others.

Ultrastructural organization and RNA labelling of hepatic ribosomes in rats fed on diets deficient in essential amino acids.

Rats were starved for 2 days and then refed on either a 25 % casein diet, a non protein diet with no amino acids, or a non protein diet with 25% amino acids. The latter diets contained either all or none of the essential amino acids or were devoid of one of them. The rats were given cytidine-3H, in one experiment 3 h and in another 24 h before death. 29 and 18 S RNA labelling of the livers were determined and liver ultrastructure examined. The specific RNA activity was highest in the rats given the diet with neither protein nor amino acids. Among the rats fed the amino acid diets, there was a tendency towards heavier specific activity in several of the groups on diets deficient in single essential amino acids as compared to the groups on the complete amino acid diet. The groups given all essential amino acids had a low labelling. The ultrastructural examination revealed heavily decreased amount of rough-surfaced endoplasmic reticulum in the groups deprived of protein and amino acids, and all essential amino acids, and also decreased amount in the groups deficient in single essential amino acids as compared to the groups given the complete amino acid diet. Free polysomes were present in large amounts in the groups fed on the deficient diets.

Tryptophan Metabolism of Rats Fed on an Amino Acid Diet

In an attempt to study on metabolic changes in rats fed on an amino acid diet devoid of one branched chain amino acid and of niacin, rats were force-fed a leucine-free, isoleucine-free, valine-free or complete amino acid diet for 3 or 4 days and killed 3 hr after the feeding on day 4 or 5 to observe the body weight changes, the urinary nitrogen and N1-methylnicotinamide (MNA), and liver tryptophanpyrrolase (TPase) and tyrosine-α-keto-glutarate transaminase (TKase) activities. The excretion of the urinary nitrogen and MNA, TPase and TKase activities, and fat content of livers of rats force-fed these amino acid deficient diets were higher than those fed the complete amino acid diet. It was further confirmed in the present study that changes in TPase activity of rats given diets devoid of one essential amino acid were in the same direction with changes in urinary MNA which was observed in the previous studies on rats given threonine-free, tryptophan-free, methionine-free, lysine-free and complete amino acid diets. However, such metabolic changes in rats fed the leucine-free diet were not so remarkable, compared with those of rats fed the other amino acid deficient diets.

Tryptophan Metabolism of Rats Fed a Threonine-free Amino Acid Diet

This study was conducted to clarify metabolic changes in rats given an amino acid diet devoid of one essential amino acid from the complete amino acid diet. At the beginning of the study, rats were force-fed the threonine- or tryptophan-free diet and the complete amino acid diet to observe the body weight changes, the urinary nitrogen and N1-methylnicotinamide (MNA), and changes in the liver enzyme activities, tryptophan pyrrolase (TPase) and tyrosine-α-ketoglutarate transaminase (TKase), and the like. It was observed that the excretion of the urinary MNA of rats force-fed a threonine-free diet was higher than that of animals fed the complete amino acid diet, and that increase of the liver TPase activity three hours after feeding was larger in the latter. It was presumed from the result that tryptophan in the diet, which is normally used for protein synthesis, was converted to nicotinic acid when protein formation was limited by the omission of threonine, and excreted in urine as MNA. There was also a remarkable increase of TKase activity 3 hours after feeding either the threonine-free diet or the complete amino acid diet, but a greater increase was observed with the deficient than with the complete diet. The mechanism of the induction of TPase and TKase activities after force-feeding of the different patterns of amino acid diets is discussed.

Quantitative Evaluation of the Threonine, Isoleucine, Valine and Phenylalanine Needs of Adult Swine for Maintenance

A completely purified diet containing crystalline L-amino acids as the sole source of dietary nitrogen was used to evaluate the threonine, isoleucine, valine and phenylalanine requirements for maintenance of the nongravid gilt. To determine the requirement for individual amino acids a quadratic regression equation was fitted to the nitrogen balance data and used to determine the amino acid intake corresponding to a nitrogen balance of 1 g/day (maintenance requirement) and zero (nitrogen equilibrium requirement). Expressed as mg/day/kg3/4, requirements for maintenance of 39, 30, 21, and 21 were found for threonine, isoleucine, valine and phenylalanine, respectively. Distinctly negative nitrogen balance resulted from a dietary void of threonine, isoleucine or valine, but a dietary void of phenylalanine (and tyrosine), although causing a reduced nitrogen balance as compared with the complete amino acid diet, did not effect negative nitrogen balance. The excretion of urea plus ammonia in the urine was directly related to the quality of the amino acid pattern fed. The urinary nitrogen differential between a deficient and an adequate level of threonine, isoleucine or valine was represented largely by urea plus ammonia. Whether suboptimal or superoptimal, the concentration of valine in the diet determined the concentration of free valine in the blood plasma.