SEARCH · PubMed Health

Results for “AMINO ACID MIXTURES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources

PubMed1982

Secretion of cholesterol, triglyceride and apolipoprotein A-I by isolated perfused liver from rats fed soybean protein and casein or their amino acid mixtures.

Isolated livers from rats fed soybean protein isolate and casein or amino acid mixtures simulating these proteins were perfused for 4 hours with Krebs-Henseleit buffer containing 0.15% glucose and 25% human red blood cells. Feeding soybean protein as compared with casein resulted in a significant reduction of the secretion of cholesterol, triglyceride and apo A-I. The results agreed well with the responses of serum counterparts reported previously. When amino acid mixture diets were fed, however, no such difference could be demonstrated, though the soy-type amino acid mixture had also been shown to decrease serum cholesterol and apo A-I. The production rate of total ketone bodies was the same, but the ratio of beta-hydroxybutyrate:acetoacetate was significantly higher in rats fed plant protein. The perfusate glucose tended to be higher on soybean protein. These differences were less clear on feeding amino acid mixtures. Neither the rate of bile flow nor the concentration of biliary bile acids and cholesterol were influenced by the type of dietary protein. These observations led us to conclude that soybean protein exerts the cholesterol-lowering action primarily through the regulation of hepatic contribution. The data also suggested that the protein-dependent difference in the concentration of serum cholesterol and apo A-I might not be explained thoroughly by the difference in the amino acid profile alone.

Amino Acids↗

PubMed1990

Prevention of central nervous system toxicity of the antitumor antibiotic acivicin by concomitant infusion of an amino acid mixture.

Acivicin is an investigational amino acid antitumor antibiotic currently being evaluated in Phase II clinical trials. In humans acivicin causes reversible, dose-limiting central nervous system (CNS) effects including somnolence, ataxia, personality changes, and hallucinations. We have observed and reported previously that acivicin-treated cats exhibit symptoms (ataxia, sedation, somnolence) resembling CNS toxicity reported in humans. We hypothesized that if acivicin uptake into brain were mediated by a saturable transport system common to endogenous amino acids, drug uptake and CNS toxicity might be blocked by elevation of normal amino acid concentrations in circulating plasma. To test this hypothesis, cats received constant-rate i.v. infusions of either saline or Aminosyn, 10% (a commercially available mixture of 16 amino acids not containing glutamine, glutamate, aspartate, or cysteine) for 4 h prior to and 18 h subsequent to administration of acivicin at a dose producing marked behavioral changes in control cats. Presence or absence of ataxia and sedation were noted at intervals after acivicin treatment. Results showed that Aminosyn infusion prevented CNS symptoms in six of eight cats. Subsequent experiments showed that acivicin levels in brain tissue of Aminosyn-treated cats were 13% of the drug levels in saline-infused cats. Acivicin levels in most peripheral tissues were also decreased significantly by Aminosyn infusion but not to the extent observed in brain. Decreased brain uptake was shown to be due to a combination of amino acid blockade of drug transport into that organ and of increased total body clearance of drug. Concomitant Aminosyn treatment did not alter the efficacy of acivicin in mice bearing L1210 leukemia or MX-1 human mammary carcinoma. Further studies demonstrated that a solution containing only four large neutral amino acids (leucine, isoleucine, phenylalanine, and valine) could also protect cats from acivicin-induced CNS toxicity, apparently without increasing acivicin total body clearance. However, a mixture of several other amino acids contained in Aminosyn (alanine, arginine, tyrosine, histidine, proline, serine, and glycine) failed to prevent CNS toxicity. We conclude that cotreatment with Aminosyn or a mixture of large neutral amino acids could protect cancer patients from acivicin-induced CNS toxicity without ablating antitumor efficacy.

Amino Acids↗

PubMed1997

Acute administration of a tryptophan-free amino acid mixture decreases 5-HT release in rat hippocampus in vivo.

The effect of oral administration of a tryptophan-free amino acid mixture or the same mixture containing tryptophan (Trp) on hippocampal serotonin (5-HT) extracellular levels was studied using in vivo brain microdialysis of freely moving rats. During chloral hydrate anesthesia rats were implanted with dialysis probes in the dorsal hippocampus, and experiments were performed 24 h later. In vehicle-treated rats, the extracellular levels of 5-hydroxyindolacetic acid (5-HIAA) and 5-HT did not change during 240 min after ingestion. Oral administration of the Trp-free amino acid mixture significantly decreased basal 5-HT and 5-HIAA output 100 min after ingestion (65 and 81% of basal value, respectively) and remained at this level for another 140 min. The amino acid mixture containing Trp failed to significantly change basal extracellular levels of 5-HT, but enhanced that of 5-HIAA by approximately 134%. Moreover, in rats receiving the Trp-free amino acid mixture, the increase of hippocampal 5-HT release induced by d-fenfluramine (206%) was smaller than that released by the same drug in rats receiving the nutritionally balanced amino acid mixture (271%). Thus these results show that removal of Trp from the balanced amino acid mixture decreases spontaneous and d-fenfluramine-induced release of 5-HT in the hippocampus. In conclusion, our study supports the hypothesis that the mood-lowering effect observed in man after ingestion of a Trp-free amino acid mixture is associated with diminished 5-HT release in the brain.

Administration, Oral↗

PubMed1979

Effect of dietary mineral composition on nutritional equivalency of amino acid mixtures and casein in rats.

The effect of dietary mineral composition on the quality of amino acid mixtures and intact casein was examined in growing rats fed for 28 days under "conventional" conditions. When 25% demineralized casein (DC) was the sole dietary protein source, the widely-used mineral mixture by Harper (MMH) supported growth poorly (3.2 g/day), but a new formula mineral mixture (MM2) containing sufficient amounts of zinc gave a growth rate of over 8 g/day for 21 days. With a crude casein (CC) diet, rats grew at the same rate regardless of mineral mixtures. The growth-supporting power of amino acid mixtures, one of which simulated casein (AA-A) and another patterned after Rogers and Harper to give maximal growth of rats (AA-B), was compared with those of DC and CC with addition of MMH or MM2. When the protein source was DC, AA-A or AA-B, MM2 significantly improved the growth over that of rats fed MMH. The growth-stimulating effect of MM2 was greater when added to DC diet than when added to AA-A diet. When MM2 was added to AA-B diet, the growth rate greatly increased and reached that of rats fed DC diet containing MM2 (over 8 g/day), showing a nutritional equivalency between the amino acid mixture and intact protein. Drawbacks inherent in MMH did not appear with CC diet, because CC contained considerable amounts of zinc. When a highly purified amino acid-sucrose diet is used, dietary minerals become most limiting for growth even under conventional conditions. Thus, the previous conflicting results concerning nutritional equivalency of amino acid mixtures and protein can be explained by inadequate mineral sources.

Amino Acids↗

PubMed1975

Jejunal absorption of an amino acid mixture simulating casein and an enzymic hydrolysate of casein prepared for oral administration to normal adults.

1. An intestinal perfusion technique was used in six normal human subjects to study absorption of sixteen individual amino acids from an amino acid mixture simulating casein and from an enzymic hydrolysate of casein, prepared for oral administration to these subjects, which consisted of a mixture of oligopeptides and free amino acids. 2. Total absorption of alpha-amino nitrogen was greater from the casein hydrolysate than from the amino acid mixture, and the considerable variation in percentage absorption of individual amino acids from the amino acid mixture was much reduced when the enzymic hydrolysate solution was perfused, as a number of amino acids which were poorly absorbed from the amino acid mixture were absorbed to a greater extent from the casein hydrolysate. 3. These findings indicate that after extensive intestinal resections or in malabsorption there might be significant nutritional advantages in the administration of protein hydrolysates rather than amino acid mixtures.

Administration, Oral↗

PubMed2004

Effect of amino acid mixture on the isolated ischemic heart.

Data show that uptake of amino acids correlates with myocardial oxygen consumption after aortic cross-clamp in humans; this suggests a direct link between amino acids and myocardial energy metabolism. The aim of this preliminary study was to investigate the anti-ischemic effects of immediate and long-term supplementation of an amino acid mixture. We tested this hypothesis on isolated rats hearts subjected to global ischemia for 30 minutes. Long-term treatment with an amino acid mixture achieved the following: (1) reduced the increase of diastolic pressure (48 +/- 3 mm Hg vs 21 +/- 4 mm Hg; p <0.05); (2) maintained the tissue content of adenosine triphosphate during ischemia (2.5 +/- 0.6 micromol/g wet wt [gww] vs 7.0 +/- 1.2 micromol/gww; p <0.05); and (3) improved the recovery of developed pressure at the end of postischemic reperfusion (11 +/- 2 mm Hg vs 38 +/- 3 mm Hg; p <0.05), reducing the release of creatine kinase (375 +/- 30 microU/min/gww vs 196 +/- 15 microU/min/gww; p <0.05) and lactate (15 +/- 1.5 mg/min/gww vs 5 +/- 1 mg/min/gww; p <0.05). We conclude that long-term supplementation of an amino acid mixture reduced myocardial ischemic damage.

Adenosine Triphosphate↗

PubMed1995

Effects of a peptide mixture with a high Fischer's ratio on serum and cerebral cortex amino acid levels and on cerebral cortex monoamine levels, compared with an amino acid mixture with a high Fischer's ratio.

Peptide mixtures with high and low Fischer's ratios (i.e., the ratio of branched-chain amino acids to aromatic amino acids), obtained from an enzymatic hydrolysate of casein, and the corresponding amino acid mixtures were intragastrically force-fed to rats. Cerebral cortex monoamines were more influenced by the ingestion of the peptide than that of the amino acid mixture.

Amino Acids↗

PubMed1977

[Changes in amino acid concentrations in plasma after oral ingestion of oligopeptides and analogous amino acid mixtures].

To what extent an oligopeptide mixture differs in equimolar dosage from an equivalent amino acid mixture after oral intake was tested on 11 subjects. The plotted course and absolute order of magnitude of the two mixtures revealed no differentiation in the total amino acid concentration of the peripheral blood plasma. The same was true of the individual free amino acids in the plasma. The only difference was found in the graphic representation of the maximum amino acid concentration of the individual test subjects, which was usually reached at an earlier date with oligopeptides than with free amino acids. The difference is even more obvious in the portal vein, as is shown in a test series not yet completed, where the plasma amino acid concentration increased at a clearly earlier date after oligopeptide substitution than after the supply of the equivalent amino acid mixture.

Amino Acids↗

PubMed1998

An amino acid mixture deficient in phenylalanine and tyrosine reduces cerebrospinal fluid catecholamine metabolites and alcohol consumption in vervet monkeys.

An amino acid mixture devoid of tryptophan, given orally, was previously shown to reduce cerebrospinal fluid levels of tryptophan and 5-hydroxyindoleacetic acid in vervet monkeys, as compared to a control mixture containing all essential amino acids. In the present study, we tested the possibility that a similar amino acid mixture containing tryptophan, but devoid of phenylalanine and tyrosine (the amino acid precursors of catecholamine neurotransmitters), would influence dopamine and noradrenaline metabolism. Five hours after the administration of this mixture to vervet monkeys, cerebrospinal fluid levels of homovanillic acid and 3-methoxy-4-hydroxyphenylethylene glycol were reduced by 27.4% and 26.9%, respectively. Both effects were statistically significant. Plasma tyrosine (-30%) and the ratio of tyrosine to the sum of other large neutral amino acids (sigmaLNAA) were also significantly reduced. The behavioral efficacy of phenylalanine/tyrosine depletion was compared with that of tryptophan depletion in a primate model of voluntary alcohol consumption. All three drinks lowered alcohol consumption, but the effects of the tryptophan-deficient amino acid mixture were not different from those of the balanced amino acid control. The phenylalanine/tyrosine-deficient drink differentially lowered alcohol consumption, consistent with other data in this species and elsewhere implicating dopamine in the rewarding effects of alcohol.

Alcohol Drinking↗

PubMed1985

Effects of amino-acid mixtures on food utilization and growth in Tenebrio molitor L.

Ten holidic diets, varying in amino-acid concentration or composition, were fed to larvae of Tenebrio molitor for four weeks at 27 +/- 0.25 degrees C and 65 +/- 5% r.h. Effects of diet on growth, food utilization and energy utilization were recorded for individual larvae. Differences in gains in fresh weight or in dry matter among larvae fed diets containing 0% to 5% of the amino-acid mixture were not demonstrated. However, larvae fed 10% or 20% of this mixture gained more than the former, but less than larvae fed a diet of ground whole wheat and brewer's yeast (9:1, w/w). When the amino-acid mixture was supplemented with alanine, aspartic acid, and serine, or with these three and asparagine, and was fed to larvae at the 10% level, growth was slower than with the unsupplemented mixture. Supplementation of the amino-acid mixture with the first three amino acids did not reduce larval growth when fed at the 20% level. Amounts of food and of energy utilized were positively correlated with larval fresh-weight and dry-matter gains. Energy utilization was negatively correlated with dietary amino-acid level. Food and energy utilization and larval growth were influenced by dietary amino acids, either metabolically or through phagostimulation.

Amino Acids↗

PubMedDate not supplied

[Elimination of phenylalanine from amino acid mixtures obtained from yeast hydrolysates and autolyzates].

In order to obtain amino acid mixtures devoid of phenylalanine, adsorption of aromatic amino acids was studied during their chromatography on ion-exchange resin IA-Ip. When 40 g of the amino acid mixture were passed through 400 ml of the swollen ion-exchange resin, phenylalanine and tyrosine were eliminated and 67% of dry substance were yielded. Ion-exchange resin adsorbed phenylalanine and tyrosine could be regenerated. The use IA-Ip is advantageous as compared with that of ion-exchange resin Amberlite IR-45 and activated charcoal.

Adsorption↗

PubMed2001

Whole-body nitrogen and splanchnic amino acid metabolism differ in rats fed mixed diets containing casein or its corresponding amino acid mixture.

Whole-body and splanchnic metabolism of dietary amino acids derived from casein (CAS) or the corresponding crystalline L-amino acid mixture (AA) were compared. Male adult rats were adapted for 9 d to two isoenergetic, isonitrogenous diets (15 g/100 g protein, 5 g/100 g fat) containing either CAS or AA. On d 10, the rats were fed a single mixed meal (3 g dry mass) containing either intrinsically (13)C-labeled goat casein or the amino acid mixture containing [U-(13)C(6)] leucine and [alpha-(15)N] lysine. Rats were killed before and 1, 3, 5 and 7 h after meal ingestion and samples of plasma, stomach wall and contents, small intestine and liver were collected. (13)C and (15)N enrichments of free and protein-bound amino acids in plasma and tissues were analyzed by gas chromatography-combustion isotope ratio mass spectrometry. Urinary nitrogen excretion was higher (P < 0.05) and weight gain lower (P < 0.05) in rats given the AA diet, indicating a lower whole-body net protein synthesis. Free (13)C-leucine from the AA diet appeared in the intestinal mucosa free pool more rapidly (P < 0.05) than the CAS-(13)C-leucine, probably due to the faster transit through the stomach of the AA group. However, the incorporation of dietary leucine into plasma and liver proteins was higher in the CAS group 7 h after the meal (P < 0.05), whereas lysine incorporation into liver protein was higher in the AA group (P < 0.05). We conclude that whole-body protein homeostasis is better supported by dietary casein-bound than crystalline free amino acids, and that protein-bound leucine, but not lysine, is used more efficiently for liver protein synthesis than dietary free leucine.

Amino Acids↗

PubMed1970

The effect of feeding with a tryptophan-free amino acid mixture on rat liver magnesium ion-activated deoxyribonucleic acid-dependent ribonucleic acid polymerase.

1. The Widnell & Tata (1966) assay method for Mg(2+)-activated DNA-dependent RNA polymerase was used for initial-velocity determinations of rat liver nuclear RNA polymerase. One unit (U) of RNA polymerase was defined as that amount of enzyme required for 1 mmol of [(3)H]GMP incorporation/min at 37 degrees C. 2. Colony fed rats were found to have a mean RNA polymerase activity of 65.9muU/mg of DNA and 18h-starved rats had a mean activity of 53.2muU/mg of DNA. Longer periods of starvation did not significantly decrease RNA polymerase activity further. 3. Rats that had been starved for 18h were used for all feeding experiments. Complete and tryptophan-deficient amino acid mixtures were given by stomach tube and the animals were killed 15-120min later. The response of RNA polymerase to the feeding with the complete amino acid mixture was rapid and almost linear over the first hour of feeding, resulting in a doubling of activity. The activity was still elevated above the starvation value at 120min after feeding. The tryptophan-deficient amino acid mixture produced a much less vigorous response about 45min after the feeding, and the activity had returned to the starvation value by 120min after the feeding. 4. The response of RNA polymerase to the feeding with the complete amino acid mixture was shown to occur within a period of less than 5min to about 10min after the feeding. 5. Pretreatment of the animals with puromycin or cycloheximide was found to abolish the 15min RNA polymerase response to the feeding with the complete amino acid mixture, but the activity of the controls was unaffected. 6. The characteristics of the RNA polymerase from 18h-starved animals and animals fed with the complete or incomplete amino acid mixtures for 1h were examined. The effects of Mg(2+) ions, pH, actinomycin D and nucleoside triphosphate omissions were determined. The [Mg(2+)]- and pH-activity profiles of the RNA polymerase from the animal fed with the complete mixture appeared to differ from those of the enzyme from the other groups, but this difference is probably not significant. 7. [5-(3)H]Orotic acid incorporation by rat liver nuclei in vivo was shown to be affected by the amino acid mixtures in a similar manner to the RNA polymerase. 8. The tryptophan concentrations of plasma and liver were determined up to 120 min after feeding with the amino acid mixtures. Feeding with the complete mixture produced a rapid increase in free tryptophan concentrations in both plasma and liver, but feeding with the incomplete mixture did not alter the plasma concentration. The liver tryptophan concentration increased at about 45min after feeding with the tryptophan-deficient diet. 9. There was a good correlation between the liver tryptophan concentration and RNA polymerase activity in all groups of animals. 10. It was concluded that the rat liver nucleus responded to an increase in amino acid supply by increased synthesis of RNA as a result of synthesis of RNA polymerase de novo. The correlation of tryptophan concentration and RNA polymerase activity appears to reflect the general amino acid concentration required to support hepatic protein synthesis and to produce new RNA polymerase. This new polymerase appears to differ from the basal RNA polymerase by its rapid synthesis and destruction, which may be a means of regulating RNA synthesis by the amino acid concentration in the liver.

Amino Acids↗

PubMed1990

Neurosecretory and trophic action on fetal rat neuroblasts induced by an amino acid mixture.

The effects of a synthetically obtained mixture of amino acids (FACE) were investigated on the trophic and neurosecretory activity of in vitro cultures of fetal rat neuronal cells. The addition of 10(-6) M FACE to the culture medium significantly increased cell DNA content. Secretions of IR-SRIF, IR-VIP, and IR-GRF were also augmented in different proportions by the presence of FACE. Time studies demonstrated that IR-SRIF was significantly increased after 48 (P less than 0.05) and 72 (P less than 0.01) hr of exposure to FACE, and IR-VIP secretion was potentiated after only 24 hr of culture. Dose-response experiments with 10(-7) to 10(-4) M FACE indicated that concentrations of 10(-5) and 10(-4) M significantly increased both somatostatin released to the medium and cell content of IR-SRIF. FACE concentrations as low as 10(-10) M augmented the secretion of IR-GRF, and there was a dose-response correlation between 10(-10) and 10(-5) M FACE. The release and cell content of IR-VIP were also increased by FACE, with a dose-response relation at concentrations of 10(-9) to 10(-6) M. It can thus be concluded that FACE has a powerful effect on the multiplication and survival of fetal cerebrocortical cells and is also an important potentiator of IR-SRIF, IR-VIP, and IR-GRF secretion.

Amino Acids↗

PubMed2000

Effect of amino acid mixtures on nasal allergic responses induced by toluene diisocyanate in mice.

We studied the effect of various amino acid mixtures on nasal allergy induced by the intranasal application of toluene diisocyanate (TDI) in mice. In Experiment 1 (Exp. 1), mice were fed a 25% casein, soy protein isolate (SPI), egg white protein (EW) or gluten diet. In Experiment 2 (Exp. 2), mice were fed a 25% amino acid mixture diets patterned after casein (AA-casein), SPI (AA-SPI), EW protein (AA-EW) or gluten (AA-gluten). In Experiment 3 3 (Exp. 3) we modified the glutamine/glutamic acid (Gln/Glu) concentrations in the amino acid mixtures. Mice were fed a 25% AA-SPI, low Gln/Glu AA-SPI (LG-AA-SPI), AA-EW or high Gln/Glu AA-EW (HG-AA-EW) diet. At the 5th week, mice were divided into sensitized (sen-) and non-sensitized (ns-) groups. The mice in sensitized groups were treated with two courses of intranasal application of toluene diisocyanate (TDI) in ethyl acetate for 5 consecutive days, separated by 9 days rest. The non-sensitized groups of mice were treated with a vehicle. Nine days after the second sensitization, all mice were provoked by TDI. Nasal responses and serum IgE concentration were studied. The findings of Exp. 1 showed that the sen-EW group exhibited a lower body weight gain, higher nasal symptom score and higher IgE concentration than the other sensitized groups. The findings dings of Exp. 2 showed that the sen-EW group had a lower body weight gain, higher nasal symptom score and higher IgE concentration than the other sensitized groups. In Exp. 3, the AA-EW group showed a higher total nasal score and IgE concentration than the HG-AA-EW group, however, the findings of LG-AA-SPI and AA-SPI were similar. These findings demonstrated that amino acid mixtures affect nasal allergy induced by the intranasal application of TDI in mice.

Administration, Intranasal↗

PubMed1992

[The characteristics of the absorption in the small intestine of 2 casein hydrolysates and of an equivalent amino acid mixture].

Using casein hydrolysates and the amino-acid mixture applied to mucosal or serosal surfaces, their effect on the transport of free glycine, glycine formed during glycyl glycine hydrolysis, and galactose, was studied in the small intestine. The data obtained suggest a mechanism of peptide transport in the enterocytes as well as a possibility of a regulatory effect of the peptides contained in casein hydrolysates on the transport of some basic nutrients.

Amino Acids↗

PubMed1975

Changes in plasma amino acid concentrations in man after ingestion of an amino acid mixture simulating casein, and a tryptic hydrolysate of casein.

1. Plasma amino acid levels have been estimated at 0, 15, 30 and 45 min after ingestion of doses of (1) an amino acid mixture simulating casein and (2) a tryptic hydrolysate of casein consisting mainly of oligopeptides. Both doses contained the same amount of nitrogen. 2. After ingestion of both preparations, there was a prompt increase in plasma amino acid levels, followed by a decrease. No such change occurred in fasting subjects. There were no significant differences between increments in plasma amino acid levels after ingestion of the amino acid mixture and the corresponding increments after ingestion of the tryptic hydrolysate. 3. Correlations were found between the areas under the curves for individual amino acid concentrations, after ingestion of the two preparations, and the amino acid composition of casein. The results do not suggest that increases in plasma amino acid levels following small doses of protein digestion products are the result of circadian changes, or that such increases are 'swamped' by absorption of amino acids from endogenous protein in the lumen of the small intestine.

Adult↗

PubMedDate not supplied

Comparison of net protein utilization of milk protein mild enzymatic hydrolysates and free amino acid mixtures with a close pattern in the rat.

The nutritive value of two nitrogen-containing mixtures, one formed from small peptides (milk protein mild enzymatic hydrolysates) and the other consisting of a mixture of free amino acids having the same pattern except for glutamine, was measured in rats with and without experimental liver and exogenous pancreas dysfunction. For this purpose, 30 animals (group N) were fitted with an indwelling duodenal catheter; 36 animals (group L) also underwent ligation and resection of the biliopancreatic duct. After a 3-day recovery period, the animals in each group, divided into three equivalent batches, were given, for 10 days, a protein-free diet ad libitum and a twice-daily duodenal infusion (5 mL) of either saline, the small peptides, or the free amino acid mixture. The nitrogen-containing mixtures provided 0.32 g of nitrogen per day. A blood sample (left side of the heart) was collected 1 hour before (five to six animals per batch) and after (five to six animals per batch) the last infusion for determination of glucose, insulin, and amino acids. After the animals were killed, their carcasses were freeze-dried, ground, and analyzed for nitrogen content. Under these conditions, the net protein utilization (the gain in body nitrogen in the animals infused with one of the two nitrogen-containing solutions in comparison with the animals infused with saline only divided by the nitrogen ingested) was calculated.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗