The glucose-alanine cycle

Felig, Philip

doi:10.1016/0026-0495(73)90269-2

Cited by 739 publications

(369 citation statements)

References 119 publications

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“…This is not the case for 15 N, which can exchange between alanine and glycine during alanine deamination in a branch reaction of the citric acid cycle. 41 Notwithstanding this label exchange, the alanine and glycine 15 N spectra ( Figure 3) show noticeable differences. However, because of this migration we focused our quantitative analysis on 13 C spectra only.…”

Section: Resultsmentioning

confidence: 98%

“…An important biosynthetic and degradation pathway for alanine involves interconversion into pyruvate and subsequently to oxaloacetate. 41 The important metabolic role and ubiquity of pyruvate allow a route for isotopic migration from 1-C to positions 2-C and 3-C. In the case of glycine biosynthesis, serine is the precursor, with the main catabolic pathway leading to CO 2 , NH 4 , and water.…”

Section: Resultsmentioning

confidence: 99%

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Orientational order of Australian spider silks as determined by solid‐state NMR

et al. 2006

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A simple solid-state NMR method was used to study the structure of 13 C-and 15 Nenriched silk from two Australian orb-web spider species, Nephila edulis and Argiope keyserlingi. Carbon-13 and 15 N spectra from alanine-or glycine-labeled oriented dragline silks were acquired with the fiber axis aligned parallel or perpendicular to the magnetic field. The fraction of oriented component was determined from each amino acid, alanine and glycine, using each nucleus independently, and attributed to the ordered crystalline domains in the silk. The relative fraction of ordered alanine was found to be higher than the fraction of ordered glycine, akin to the observation of alanine-rich domains in silk-worm (Bombyx mori) silk. A higher degree of crystallinity was observed in the dragline silk of N. edulis compared with A. keyserlingi, which correlates with the superior mechanical properties of the former #

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Orientational order of Australian spider silks as determined by solid‐state NMR

et al. 2006

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“…10,11,17 In food deprivation or restriction, glycaemia is maintained at the expense of 3C fragments, essentially derived from amino acids through the glucose-alanine cycle. 27 However, under OE treatment there is no need for an enhanced liver glucose output, since peripheral utilisation of glucose is decreased, 28 which results in the sparing of protein. 10,11 However, when the rat is subjected to an additional and severe decrease in food available, the emergency mechanisms that maintain glycaemia are nevertheless activated.…”

Section: Discussionmentioning

confidence: 99%

Combined effects of oral oleoyl-estrone and limited food intake on body composition of young overweight male rats

2006

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Objective: The combined effects of limited food intake and OE treatment have been analysed in order to determine whether hypocaloric diets enhance the slimming effects of OE on mature overweight male rats. Two levels of dietary limitation at 50 and 25% of a standard intake were established, roughly corresponding to the human LCDs and VLCDs. Design: Wistar male rats (6 weeks old) were made overweight by a cafeteria diet. After transition to standard diet, they were subjected to food restriction: down to 50 or 25% with respect to the transition period. Half the animals were given daily oral gavages of 10 nmol/g oleoyl-estrone (OE), and the rest received only the vehicle during 10 days. Measurements: Changes in weight and body composition: water, lipid, protein or gross energy were determined by comparing the final pool size with that of day 0, calculated from the initial body weight and the composition of untreated rats. Energy and nitrogen balances were estimated. Plasma levels of metabolites and hormones were also measured. Results: OE induced changes in body composition similar to those elicited by a 50% reduction in food, with massive loss of lipid and energy. OE-treated rats ate less than the controls, but additional effects on body composition on reduced diet were minimal. OE improved metabolic homoeostasis: better maintained glycaemia, lower cholesterol and shallower hormonal changes, but at the expense of slightly increased protein mobilisation. Conclusions: The data presented suggest that no advantages are accomplished by combining OE treatment and hypocaloric diets compared with OE alone, at least under the experimental conditions tested, since the effects were not additive. Despite OE affecting food intake, mechanisms other than that are deemed responsible for the mobilisation of body fat, since intake alone cannot explain the effects on body weight, nor the metabolic and hormonal changes in OE-treated rats. It is concluded that the combination of food restriction and OE may result in unwanted increased protein mobilisation with no synergy between both slimming treatments.

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“…While the plasma amino acid profile in our patients was not totally typical for protein-calorie malnutrition (21,22), their general hypoaminoacidaemia and deficiency of important substrates of ghicogenesis, especially alanine (23,24), are seen as signs of severe protein-calorie deficiency (20,22,25), possibly due to hypermetabolism and poor nutrient absorption (26,27). We have no evidence that their taurine deficit resulted from dietary amino acid deficiencies as suggested by others (12).…”

Section: Discussionmentioning

confidence: 41%

The Plasma Amino Acid Profile and its Relationships to Standard Quantities of Liver Function in Infants and Children with Extrahepatic Biliary Atresia and Preterminal Liver Cirrhosis

Byrd

Wiltfang²,

Rodeck³

et al. 1993

Clinical Chemistry and Laboratory Medicine

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Summary:The absolute and relative concentrations of 16 plasma amino acids in 48 mostly dystrophic infants and children (median of age 1 1 A years) with extrahepatic biliary atresia and mainly stable preterminal cirrhosis were compared with those of controls. Patient plasma amino acid data were analysed statistically for diagnostic usefulness and correlated with standard biochemical quantities of liver function and of liver perfusion. In the patients the total amounts of non-essential and essential amino acids were reduced by 19%, and with the same significance (p < 0.0005). Plasma tyrosine was increased (+40%), while taurine (-44%) and branched chain amino acids (+28.8% to -34.7%) were decreased. Methionine values varied widely. In the molar fractional plasma amino acid profile, only alanine, valine, and leucine were decreased, while threonine, methionine, tyrosine, phenylalanine, ornithine, and serine were increased. Discriminate function analysis showed that the plasma amino acid data discriminated 93.8% of the patients from controls. The concentrations of some amino acids in plasma seemed to have been influenced by protein-calorie deficiency in the patients. The valine/tyrosine ratio and the Fischer index (ratio branched chain/aromatic amino acids) were significantly reduced in the patients versus controls (1.54 + 0.55 vs 3.08 + 0.55 and 1.66 + 0.39 vs 3.00 + 0.48). A number of significant correlations (range of r: 0.37 -0.59, p < 0.05, 30-48 data pairs) were calculated between plasma amino acid data and several standard biochemical quantities of liver function. The statistical analyses also showed that the Fischer index began to decrease gradually and linearly early in the progression of liver failure. It is concluded that plasma amino acid data can be useful in the evaluation of the progression of liver failure and possibly of the nutritional status in liver transplant candidates with biliary atresia.

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The glucose-alanine cycle

Cited by 739 publications

References 119 publications

Orientational order of Australian spider silks as determined by solid‐state NMR

Orientational order of Australian spider silks as determined by solid‐state NMR

Combined effects of oral oleoyl-estrone and limited food intake on body composition of young overweight male rats

The Plasma Amino Acid Profile and its Relationships to Standard Quantities of Liver Function in Infants and Children with Extrahepatic Biliary Atresia and Preterminal Liver Cirrhosis

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