scholarly journals The combination of proteins, amino-acids, etc., with acids and alkalis, and their combining weights as determined by physico-chemical measurements.—Preliminary paper

1925 ◽  
Vol 97 (684) ◽  
pp. 364-386 ◽  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Hydrogen Ion ◽  
Acid Mixture ◽  
Modus Operandi ◽  
End Points ◽  
Basic Group ◽  
Chemical Measurements ◽  
Physico Chemical ◽  
The Given

In previous communications (1) the writer described a system for estimating and characterising the amino-acids which depends on the k a and k b values of these bodies. The modus operandi of the technique is to determine the amounts of acid or alkali required to titrate the amino-acid- (or dipeptide-, etc.) solutions over definite ranges of p H or to definite p H end-points; it rests on the knowledge that the weaker an acidic (or a basic) group the greater will be the degree of alkalinity (or acidity) developed during its titration with strong alkali (or acid). After the addition of each increment of acid or alkali the p H is determined. One plots p H against, not the actual amount of alkali (or acid) added, but against this amount corrected for the “hydrogen ion error.” The correction is made by subtracting from the amount of alkali (or acid) added, the amount of alkali (or acid) which would have to be added to a hypothetical blank consisting of water only in order to produce the same total volume of liquid having the same p H as the amino-acid alkali (or acid) mixture. The corrected value represents the amount of alkali (or acid) required to bring the amino-acid itself to the given p H value, while the correction is the amount required by the water present.

scholarly journals Effect of co-ingestion of amino acids with rice on glycaemic and insulinaemic response

2015 ◽  
Vol 114 (11) ◽  
pp. 1845-1851 ◽  
Author(s):  
Yean Yean Soong ◽  
Joseph Lim ◽  
Lijuan Sun ◽  
Christiani Jeyakumar Henry
Keyword(s):  
Amino Acids ◽  
Blood Glucose ◽  
Amino Acid ◽  
Glycaemic Index ◽  
Amino Acid Mixture ◽  
Postprandial Blood Glucose ◽  
Acid Mixture ◽  
White Rice ◽  
Amino Acid Mixtures

AbstractConsumption of high glycaemic index (GI) and glycaemic response (GR) food such as white rice has been implicated in the development of type 2 diabetes. Previous studies have reported the ability of individual amino acids to reduce GR of carbohydrate-rich foods. Because of the bitter flavour of amino acids, they have rarely been used to reduce GR. We now report the use of a palatable, preformed amino acid mixture in the form of essence of chicken. In all, sixteen healthy male Chinese were served 68 or 136 ml amino acid mixture together with rice, or 15 or 30 min before consumption of white rice. Postprandial blood glucose and plasma insulin concentrations were measured at fasting and every 15 min after consumption of the meal until 60 min after the consumption of the white rice. Subsequent blood samples were taken at 30-min intervals until 210 min. The co-ingestion of 68 ml of amino acid mixture with white rice produced the best results in reducing the peak blood glucose and GR of white rice without increasing the insulinaemic response. It is postulated that amino acid mixtures prime β-cell insulin secretion and peripheral tissue uptake of glucose. The use of ready-to-drink amino acid mixtures may be a useful strategy for lowering the high-GI rice diets consumed in Asia.

Liver extract and its free amino acids equally stimulate gastric acid secretion

1980 ◽  
Vol 239 (6) ◽  
pp. G493-G496 ◽  
Author(s):  
E. J. Feldman ◽  
M. I. Grossman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Free Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Liver Extract ◽  
Amino Acid Mixture ◽  
Acid Mixture

Using intragastric titration in dogs with gastric fistulas, dose-response studies were carried out with liver extract and with a mixture of amino acids that matched the free amino acids found in liver extract. All solutions were adjusted to pH 7.0 and osmolality to 290 mosmol x kg-1. Doses are expressed as the sum of the concentrations of all free amino acids. At each dose studied (free amino acid concentration: 2.8, 5.6, 11, 23, and 45 mM), acid secretion in response to the free amino acid mixture was not significantly different from that of liver extract. The peak response to both liver extract and the free amino acid mixture occurred with the 23-mM dose and represented about 60% of the maximal response to histamine. The serum concentrations of gastrin after liver extract and the amino acid mixture were not significantly different. It is concluded that in dogs with gastric fistula, gastric acid secretion and release of gastrin were not significantly different in response to liver extract and to a mixture of amino acids that simulated the free amino acid content of liver extract.

Effect of hyperinsulinemia and hyperaminoacidemia on muscle and liver protein synthesis in lactating goats

1994 ◽  
Vol 267 (6) ◽  
pp. E877-E885 ◽  
Author(s):  
I. Tauveron ◽  
D. Larbaud ◽  
C. Champredon ◽  
E. Debras ◽  
S. Tesseraud ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Skeletal Muscles ◽  
Constant Infusion ◽  
Acid Mixture ◽  
Liver Protein ◽  
Group I ◽  
Lactating Goats ◽  
Group A

The experiment was carried out to clarify the roles of insulin and amino acids on protein synthesis in fed lactating goats (30 days postpartum). Protein synthesis in the liver and various skeletal muscles was assessed after an intravenous injection of a large dose of unlabeled valine containing a tracer dose of L-[2,3,4-3H]valine. The animals were divided into three groups. Group I was infused with insulin (1.7 mumol/min) for 2.5 h under glucose, potassium, and amino acid replacement. Group A was infused with an amino acid mixture to create stable hyperaminoacidemia for 2.5 h. Group C animals were controls. The fractional synthesis rates (FSR) were 31.5 +/- 2.2, 6.5 +/- 0.4, 4.3 +/- 0.8, 4.0 +/- 1.2, 3.9 +/- 1.2, and 3.6 +/- 0.4%/day (SD) in liver, masseter, diaphragm, anconeus, semitendinosus, and longissimus dorsi, respectively, for group C. Neither hyperinsulinemia in group I nor hyperaminoacidemia in group A had not affected by hyperinsulinemia but was stimulated by hyperaminoacidemia (+30%, P < 0.05). In contrast to previous experiments in which a labeled amino acid was constantly infused, this study revealed a stimulating effect of amino acids on protein synthesis in the liver but not in skeletal muscles. As previously observed in studies with the constant-infusion method, insulin had no effect on protein synthesis.

An abundant supply of amino acids enhances the metabolic effect of exercise on muscle protein

1997 ◽  
Vol 273 (1) ◽  
pp. E122-E129 ◽  
Author(s):  
G. Biolo ◽  
K. D. Tipton ◽  
S. Klein ◽  
R. R. Wolfe
Keyword(s):  
Amino Acids ◽  
Blood Flow ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Protein Kinetics ◽  
Amino Acid Infusion

Six normal untrained men were studied during the intravenous infusion of a balanced amino acid mixture (approximately 0.15 g.kg-1.h-1 for 3 h) at rest and after a leg resistance exercise routine to test the influence of exercise on the regulation of muscle protein kinetics by hyperaminoacidemia. Leg muscle protein kinetics and transport of selected amino acids (alanine, phenylalanine, leucine, and lysine) were isotopically determined using a model based on arteriovenous blood samples and muscle biopsy. The intravenous amino acid infusion resulted in comparable increases in arterial amino acid concentrations at rest and after exercise, whereas leg blood flow was 64 +/- 5% greater after exercise than at rest. During hyperaminoacidemia, the increases in amino acid transport above basal were 30-100% greater after exercise than at rest. Increases in muscle protein synthesis were also greater after exercise than at rest (291 +/- 42% vs. 141 +/- 45%). Muscle protein breakdown was not significantly affected by hyperminoacidemia either at rest or after exercise. We conclude that the stimulatory effect of exogenous amino acids on muscle protein synthesis is enhanced by prior exercise, perhaps in part because of enhanced blood flow. Our results imply that protein intake immediately after exercise may be more anabolic than when ingested at some later time.

Amino Acids in Premature Infants

PEDIATRICS ◽  
1988 ◽  
Vol 82 (4) ◽  
pp. 680-680
Author(s):  
NIELS C. R. RÄIHÄ
Keyword(s):  
Amino Acids ◽  
Birth Weight ◽  
Amino Acid ◽  
Parenteral Nutrition ◽  
Premature Infants ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Metabolic Capacity ◽  
Low Birth Weight Infants ◽  
Term Infants

To the Editor.— In a recent paper in Pediatrics, Heird et al1 reported their evaluation of the use of a new amino acid mixture for parenteral nutrition in low birth weight infants. On the basis of their results the authors made the following statement: "These observations refute the concept that the metabolic capacity of LBW infants for amino acids is limited in comparison to that of term infants, older infants, and chi1dren."1(p49) Such a conclusion is not justified on the basis of the presented data.

Amino-acid-dependent modulation of amino acid transport in Xenopus laevis oocytes.

1996 ◽  
Vol 199 (4) ◽  
pp. 923-931 ◽  
Author(s):  
P M Taylor ◽  
S Kaur ◽  
B Mackenzie ◽  
G J Peter
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Xenopus Laevis ◽  
Amino Acid Transport ◽  
Acid Mixture ◽  
Xenopus Laevis Oocytes ◽  
Amino Acid Transporters ◽  
Amino Acid Supplementation ◽  
Acid Transport ◽  
Acid Supplementation

We have measured rates of uptake of arginine, glutamine, glutamate, serine, phenylalanine and glycine in Xenopus laevis oocytes cultured for periods of up to 24h in saline in the presence or absence of a mixture of 20 amino acids at concentrations approximating those in Xenopus plasma. Amino acid supplementation increased the total intracellular amino acid concentration from 8.2 to 18.4 nmol per oocyte. Specific Na(+)-dependent amino acid transporters (systems B0,+, Xag-) exhibit 'adaptive regulation' (up-regulation during amino acid deprivation and down-regulation during amino acid supplementation). Na(+)-independent transporters of glutamate, glutamine and glycine (including system asc) display an opposite modulation in activity, which may help to combat amino-acid-induced oxidative stress by increasing the supply of glutathione precursors. Single amino acids at physiological plasma concentrations (0.47 mmol l-1 L-alanine, 0.08 mmol l-1 L-glutamate) mimicked at least some effects of the amino acid mixture. The mechanisms of transport modulation do not appear to include trans-amino acid or membrane potential effects and, in the case of Na(+)-independent transport, are independent of protein or mRNA synthesis. Furthermore, activation of protein kinase C by phorbol 12-myristate 13-acetate did not significantly affect endogenous glutamine and glutamate transport. The Xenopus oocyte appears to possess endogenous signalling mechanisms for selectively modulating the activity of amino acid transport proteins expressed in its surface membranes, a factor for consideration when using oocytes as an expression system for structure-function studies of cloned amino acid transporters.

Effects of amino acids and gastric inhibitory polypeptide on insulin release in dogs

1982 ◽  
Vol 242 (1) ◽  
pp. E53-E58
Author(s):  
J. G. Yovos ◽  
T. M. O'Dorisio ◽  
T. N. Pappas ◽  
S. Cataland ◽  
F. B. Thomas ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Insulin Release ◽  
Insulin Response ◽  
Gastric Inhibitory Polypeptide ◽  
Amino Acid Mixture ◽  
Group Iv ◽  
Acid Mixture ◽  
Group Iii ◽  
Group I

Insulin release following intravenous administration of an amino acid solution with and without a simultaneous infusion of varying amounts of porcine gastric inhibitory polypeptide (GIP) was studied in dogs. Group I received a 10-amino acid mixture (300 mosmol/kg iv) at 16.6 ml/min for 1 h; group II, amino acid mixture plus 0.5 micrograms.kg-1.h-1 porcine GIP; group III, amino acid mixture plus 1.0 micrograms.kg-1.h-1 of GIP; group IV (a and b) received either 0.5 or 1.0 micrograms.kg-1.h-1 of GIP alone. Compared to group I, groups II and III had a greater insulin response during the first 30 min of the infusion. Group] IV (a and b) showed no insulin release. Glucose concentrations showed no significant change in all groups. From these results, it is concluded that insulin release after intravenous infusion of an amino acid mixture plus GIP is greater than after amino acids or GIP alone. It appears that this effect is more pronounced in the early phase of insulin release.

Uptake and metabolism of amino acids by the dog liver perfused in situ

1962 ◽  
Vol 202 (3) ◽  
pp. 407-414 ◽  
Author(s):  
Rapier H. McMenamy ◽  
William C. Shoemaker ◽  
Jonas E. Richmond ◽  
David Elwyn
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Sharp Rise ◽  
Dog Blood ◽  
Dog Liver ◽  
Amino Acid Concentrations ◽  
Uptake And Metabolism

Dog livers were perfused in situ for periods up to 6 hr with dog blood recycled through a pump-oxygenator. An amino acid mixture was administered for 90 min. Concentrations of amino acids were determined at intervals of 30 min or more. Rates of uptake and metabolism were calculated. After the start of perfusion, there is a fall in most plasma amino acid concentrations and a reciprocal rise in liver amino acids. Addition of amino acids causes a sharp rise in plasma amino acids. There is a rapid uptake of most of the amino acids by liver, although the concentrations of amino acids in liver fail to rise appreciably. Notable exceptions are valine, leucine, and isoleucine. Uptake of amino acids stimulates: a) an increase in the rate of synthesis of urea which ultimately accounts for 90% of the metabolized amino acids; b) a net synthesis of ornithine; and c) net noncatabolic metabolism of amino acids which may in part be protein synthesis. The results support the view that the liver temporarily stores a part of ingested amino acids as proteins, and subsequently makes them available to other organs.

Chromatographic Separation of Free Amino Acids in Table Sirups

1971 ◽  
Vol 54 (1) ◽  
pp. 61-65
Author(s):  
Arthur Russell Johnson ◽  
Richard L Corliss ◽  
Enrique Fernandez-Flores
Keyword(s):  
Amino Acids ◽  
Quantitative Analysis ◽  
Amino Acid ◽  
Ion Exchange ◽  
Free Amino Acids ◽  
Free Amino ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Butyl Esters ◽  
Tlc Analysis

Abstract Qualitative chromatographic methods for the separation of free amino acids in table sirups are presented to aid in the development of chemical indices of composition which may be useful in establishing the identity of sirups and detecting their adulteration. Free amino acids in 2 table sirups were isolated on ion exchange columns and eluted with dilute ammonia. The concentrated amino acid mixture in the eluate was spotted directly on silica gel G plates for TLC analysis, or the amino acids were converted to their N-trifluoroacetyl n-butyl esters for GLC analysis. As many as 16 amino acids were qualitatively separated and identified and a potential for quantitative analysis was demonstrated.

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