Free Glutamine Research Articles

Formation of High Levels of Acrylamide during the Processing of Flour Derived from Sulfate-Deprived Wheat

When wheat was grown under conditions of severe sulfate depletion, dramatic increases in the concentration of free asparagine were found in the grain of up to 30 times as compared to samples receiving the normal levels of sulfate fertilizer. The effect was observed both in plants grown in pots, where the levels of nutrients were carefully controlled, and in plants grown in field trials on soil with poor levels of natural nutrients where sulfate fertilizer was applied at levels from 0 to 40 kg sulfur/Ha. Many of the other free amino acids were present at higher levels in the sulfate-deprived wheat, but the levels of free glutamine showed increases similar to those observed for asparagine. In baked cereal products, asparagine is the precursor of the suspect carcinogen acrylamide, and when flours from the sulfate-deprived wheat were heated at 160 degrees C for 20 min, levels of acrylamide between 2600 and 5200 microg/kg were found as compared to 600-900 microg/kg in wheat grown with normal levels of sulfate fertilization.

Free glutamine as a major precursor of brown products and fluorophores in Maillard reaction systems

Glutamine is one of the most abundant free amino acid found in raw food. In this study, the contribution of free glutamine to nonenzymatic browning and fluorescence was investigated using an aqueous model system with methylglyoxal. The results indicated that glutamine contributed to the Maillard reaction via two pathways. First, the hydrolysis of the amide bond of glutamine led to the release of ammonia which was implicated in the formation of brown color and fluorescence. Among other nitrogen donors tested (asparagine, glutamic acid and urea) our results demonstrated that free glutamine was a major source of ammonia during heating. When heated at 120 and 180 degrees C, 100% of ammonia was released from glutamine after 60 and 10 min, respectively. The second pathway involved a direct Maillard reaction with the alpha-amino group of glutamine. Both pathways led to a rapid and complete destruction of glutamine when heated in the model systems. With reference to the Maillard browning (absorbance at 420 nm) glutamine turned out to be the most reactive amine, followed by asparagine, glutamate, ammonia and urea. Maximum fluorescence (excitation and emission wavelengths at 330 and 450 nm, respectively) was also observed with glutamine followed by urea and ammonia. Overall this study suggested that free glutamine predominantly contributes to the color and fluorescence formations of foodstuffs.

Arginine-enriched diet limits plasma and muscle glutamine depletion in head-injured rats

Objective Injury is associated with a depletion in glutamine (GLN) pools, which may contribute to impairment of immune and nutritional statuses. Total parenteral nutrition enriched with arginine (ARG) is able to generate GLN in surgical patients. We hypothesized that this same concept may be applicable to enteral administration and could be extended to muscle GLN reserves. This study investigated the ability of an enteral formula enriched with ARG to restore the GLN pools in an experimental model of head injury. Methods Twenty-five male Sprague-Dawley rats were randomized into 4 groups: ad libitum access to food, head injury plus free access to nutrition, head injury plus standard enteral nutrition (Sondalis), and an immune-enhancing diet (IED). The two enteral diets were adjusted to be isocaloric (290 kcal · kg −1 · d −1) and isonitrogenous (3.29 g · kg −1 · d −1) and were delivered for 4 d (24 h/24 h). After sacrifice, plasma and muscle amino acids were determined. Results Head injury was associated with a large depletion of muscle and plasma GLN pools that were restored by IED administration but not by the standard diet. Moreover, the IED but not the standard diet improved or normalized ornithine and glutamate pools, suggesting that the modification of GLN pools is related to ARG administration. Conclusion In our model of head injury, our IED, a diet without free GLN, is efficient in restoring the plasma and muscle pools of GLN, probably due to its high ARG content.

Total glutamine content in human milk is not influenced by gestational age

Glutamine may be a conditionally indispensable amino acid in neonates and should be given in adequate amounts. Reliable information concerning the glutamine content of human milk is lacking. To assess total glutamine content in human milk using a novel analytical procedure, and to evaluate the potential influence of time of delivery and lactational stage. The content of free and protein-bound glutamine was assessed in transitional (days 4-7 of lactation) and mature (days 29-34) human milk, after preterm (<35 wk of gestation, n=20) or term (>37 wk, n=20) delivery. Milk samples were obtained by manual expression and stored at <or=70 degrees C. Measurement of protein-bound glutamine was performed after stabilization by bis(1,1-trifluoroacetoxy)iodobenzene (BTI). Free glutamine was detected by HPLC. There was no difference concerning glutamine content in human milk after term or preterm delivery (median of 5000 vs 4960 micromol/l milk). The protein-bound glutamine content decreased with the duration of lactation (6230 vs 4540 micromol/l milk). Free glutamine accounted for only 3-10% of the protein-bound glutamine content. The free glutamine content showed a high variability after preterm and term delivery. This study presents for the first time data on glutamine intake in preterm and term neonates fed human milk. With these data, it is possible to formulate adequately composed nutritional therapy for infants at risk of glutamine imbalance.

188 THE IMPACT OF OIL SOURCE AND TYPE OF GLUTAMINE ON MEDIA EQUILIBRATION TIMES AND EMBRYO DEVELOPMENT

Recently, there has been much debate involving the time necessary to effectively equilibrate an embryo culture system, i.e. dishes, media, and oil. Glutamine present in the culture medium spontaneously deaminates at 37�C to release embryo-toxic ammonium. Additionally, the source of the oil overlay can impact the culture environment. A sub-optimal oil overlay, combined with free glutamine (Gln), could effectively become embryo-toxic over a short time period (&amp;lt;48 h). Therefore, the aim of this study was to determine how times of media equilibration, using various combinations of oil source and type of Gln, affect embryo development. Zygotes were collected from 4-week-old CF1 outbred female mice following superovulation and mating. Embryos were cultured in groups of 10 in 20-�L drops of medium G1.2. Initially, embryos were cultured in one of 4 treatment media. In this 2 � 2 factorial design, the culture medium was pre-equilibrated 18 h prior to embryo retrieval and contained free Gln or the heat-stable dipeptide alanyl-glutamine (AlaGln), combined with an oil source of either Sigma mineral oil (Sigma-Aldrich Corp., St Louis, MO, USA) or Ovoil paraffin oil (Vitrolife, Inc., Englewood, CO, USA). The initial study was then repeated using only the best and worst case groups to determine the effect of incubation time as a variable (either 2 h or 18 h). Blastocyst development and total cell numbers were analyzed after 72 h of culture, and differences between treatments were assessed using Fisher&amp;apos;s exact test and Student&amp;apos;s t-test. After 18 h of pre-equilibration (n e 300 embryos/treatment), blastocyst development in Ovoil + AlaGln (38.6%) was significantly greater when compared to: Ovoil + Gln: 25.5% (P &amp;lt; 0.01), Sigma + AlaGln: 12.8% (P &amp;lt; 0.01), and Sigma + Gln: 11.9% (P &amp;lt; 0.01). Additionally, the total cell numbers in comparison to Ovoil + AlaGln (44.6 � 10) were significantly decreased: 35.5 � 7 (P &amp;lt; 0.001), 34.9 � 9 (P &amp;lt; 0.001), and 29.9 � 9 (P &amp;lt; 0.001), respectively. In the second experiment, blastocyst development and total cell number between Ovoil + AlaGln (n = 224) and Sigma + Gln (n = 264) after 18 h of pre-equilibration were: 40.4% vs. 9.9% (P &amp;lt; 0.01) and 46.6 � 9 vs. 29.4 � 9 P &amp;lt; 0.001), respectively. However, after 2 h of pre-equilibration, the results between Ovoil + AlaGln (n = 260) and Sigma + Gln (n = 284) were: 42.3% vs. 18.3% (P &amp;lt; 0.01) and 46.9 � 10 vs. 33.6 � 6 (P &amp;lt; 0.001), respectively. Therefore, when comparing blastocyst development and total cell number between pre-equilibration times (2 h vs. 18 h), the Ovoil + AlaGln group, 42.3% vs. 40.4% and 46.9 � 10 vs. 46.6 � 9, showed no significant differences, respectively. In contrast, the Sigma + Gln group produced significant differences for both blastocyst development, 18.3% vs. 9.9% (P &amp;lt; 0.01), and total cell number, 33.6 � 6 vs. 29.4 � 9 (P &amp;lt; 0.05), between pre-equilibration times (2 h vs. 18 h), respectively. Data presented confirm the need for an alternative source of glutamine in embryo culture media. The data also indicate that the source of oil has a profound effect on the experimental outcome. Using the appropriate oil and form of Gln means that media can be safely equilibrated for 18 h.

Effects of an amino acid solution enriched with either branched chain amino acids or ornithine-α-ketoglutarate on the postoperative intracellular amino acid concentration of skeletal muscle

Patients undergoing elective cholecystectomy provide a highly reproducible model of the effects of trauma on intermediary metabolism. Three parenteral nutrition regimens were given to groups of eight such patients. An isonitrogenous total parenteral nutrition, including a commercially available amino acid solution, an amino acid solution enriched with branched chain amino acids or one supplemented with ornithine-alpha-ketoglutarate, was given after operation. The intra cellular free amino acid concentrations of skeletal muscle were determined in tissue specimens obtained before operation and on the third postoperative day using a percutaneous needle biopsy technique. The mean (s.e.m.) decrease in the concentrations of free intracellular glutamine on the third postoperative day was less pronounced (P less than 0.05) in the ornithine-alpha-ketoglutarate group (18.8(7.5)per cent) than in the control group (39.4(5.1)per cent) or the branched chain amino acid group (45.3(6.1)per cent). In conclusion, in the immediate postoperative period total parenteral nutrition supplemented with ornithine-alpha-ketoglutarate countered the decline in the muscle free glutamine. No difference in this parameter was seen between the control group and the branched chain amino acid group.

Neutrophil Glutamine Deficiency in Relation to Genotype in Children with Cystic Fibrosis

Pulmonary disease in cystic fibrosis (CF) is characterized by a chronic neutrophil-dominated inflammation of lung tissue. Inasmuch as some amino acids (AA) play a pivotal role in various aspects of neutrophil metabolism, the aim of this study was to investigate a possible alteration of neutrophil AA metabolism and to evaluate its relation (if any) with the genotype. We performed plasma and neutrophil AA analysis in 26 CF patients with known genotype, 10 patients with non-CF bronchiectasis, and 20 normal subjects. The CF group showed a significant decrease of free intracellular neutrophil glutamine (Gln) content compared with controls and the non-CF bronchiectasis group. In the latter group, levels of neutrophil Gln were significantly lower compared with the controls. Amino acid plasma concentration in non-CF bronchiectasis showed a decrease of Gln and taurine compared with controls. Neutrophil Gln content showed values significantly lower in CF patients with severe mutations (class I, II, and III mutations) compared with mild mutations (class IV and V mutations). Results of our study add further evidence for intrinsic neutrophil alterations that could play an important role in the pathogenesis of chronic pulmonary disease in CF patients.

INHIBITION OF Na,K-ATPASE ACTIVITY REDUCES BABESIA GIBSONI INFECTION OF CANINE ERYTHROCYTES WITH INHERITED HIGH K, LOW Na CONCENTRATIONS

Babesia gibsoni multiplies well in canine red blood cells (RBCs) containing high concentrations of potassium (HK), reduced glutathione, and free amino acids as a result of an inherited high Na,K-ATPase activity, i.e., HK RBCs. To determine the role of Na,K-ATPase in the multiplication of B. gibsoni, the effect of ouabain on the proliferation of the parasites in HK RBCs was investigated. To determine the direct effect of ouabain on the parasites, the proliferation of the parasites in normal canine RBCs containing low potassium (LK) and high sodium concentrations, i.e., LK RBCs, which completely lack Na,K-ATPase activity, was observed. Ouabain at 0.1 mM significantly suppressed the multiplication of B. gibsoni in HK RBCs in vitro, whereas it had no effect on the parasites in LK RBCs. The results suggest that the multiplication of B. gibsoni in HK RBCs depends mainly on the presence of Na,K-ATPase in the cells. Therefore, the effects of ouabain on the intracellular cation and free amino acid composition of the HK RBCs were examined. In HK RBCs incubated with ouabain, a marked decrease in the concentration of potassium and an increase in sodium were observed, together with a decrease in the number of parasitized cells. These results suggest that the intracellular cation composition maintained by Na,K-ATPase might be advantageous to the parasites. Moreover, the concentrations of some free amino acids, i.e., asparagine, aspartate, glutamate, glutamine, glycine, and histidine, were markedly decreased in HK RBCs incubated with ouabain. Decreased concentrations of the free amino acids induced by inhibition of Na,K-ATPase seemed to affect the multiplication of B. gibsoni in HK RBCs. Based on these results, it is clear that the high Na,K-ATPase activity in HK RBCs contributes to the proliferation of B. gibsoni by maintaining high potassium and low sodium concentrations, as well as high concentrations of some free amino acids in the cells.

The Effect of Dipeptiven in Patients after Allogenic Hematologic Stem Cell Transplantation.

Total parenteral nutrition (TPN) is provided to patients undergoing allogenic hematologic stem cell transplantation (allo-HSCT) to help minimize nutritional consequences of both conditioning regimens as well as complications resulting from the procedure such as GVHD, VOD and so on, and glutamine could to improve the clinical course of patients after transplantation while given with parenteral nutrition as it is considered that it has stimulatory effects on lymphocytes and mucosa cells in vitro. In the study, we investigated the effect of dipeptiven, N(2)-L-Alanyl-L-Glutamine, which has dipeptides as free glutamine is rather unstable and poorly soluble, added to standard TPN preparations on complication and recovery of patients with allo-HSCT. 40 patients who suffered hematologic malignancies and received allo-HSCT were randomly assigned to receive either standard TPN (control group, n=20), or dipeptiven supplemented TPN (DPT group, n=20). The Bu/Cy2 regimen was used in conditioning with Bu (16mg/kg) plus Cy (120mg/kg) and all patients were given mycophenolate mofetil, CsA and MTX to prevent GVHD. The nutritiona support was started about 1 to 12 days after transplantation and 1.5ml/kg.d dipeptiven was added to the DPT group. During the period of nutritiona support, serum albumin, total protein, creatinine, total bilirubin, leukocytes, lymphocytes were monitored, and time to neutrophil engraftment, decrease of body weight, hospital stays, and other data related to hospital infection and acute GVHD were evaluated for all patients. As a result, the levels of serum albumin fell in the two groups on the 7-day, but on the 28-day those in the DPT group returned to normal and were significantly better than those in the control group (P<0.05). The total bilirubin and creatinine concentration did not change much. And lymphocytes of the patients in the DPT group recovered more rapidly than in the control group (P<0.05). There were less cases with clinical infection and microbial colonization in the DPT group than the control group (10 vs 16,11 vs 17, P<0.05). Also days for antibiotic requirements, days of diarrhea, changes of body weight and hospital stays reduced in the DPT group (16.5±10.6d vs 25.4±16.3d, 4.7±4.5d vs 8.2±6.0d, 2.0±2.0kg vs 3.3±1.6kg, 49.2±18.8d vs 58.0±20.2d, P<0.05, respectively). There were no different between the two groups of incidence of acute GVHD. In the conclusion, DPT-supplemented parenteral nutrition was beneficial in allo-HSCT patients for the nutritional status improving, the incidence of infection and damage of intestine, liver diminishing were all reduced, and the incidence of acute GVHD not increasing.

Human Milk Banking: Influence of Different Pasteurization Temperatures on Levels of Protein Sulfur Amino Acids and Some Free Amino Acids

ABSTRACTHuman milk is frequently heat‐treated in hospitals, particularly milk that is banked, to destroy contaminating bacteria and viruses, but this treatment simultaneously reduces the content of some vitamins, enzymes, and immunological and nutritional factors. This study was performed to find the optimal conditions for heat treatment. The effects of 2 pasteurization temperatures on levels of protein sulfur amino acids (methionine, cystine) and some free amino acids (taurine, glutamine, glutamic acid) in light of the oxidative instability that occurs especially during thermal treatment were examined. These substances in raw human milk and in milk treated at 56.5 °C and 62.5 °C for 30 min were compared. Samples of mature human milk from all feeds over 24 h were obtained from 13 healthy well‐nourished mothers of term infants. Each sample was divided into 3 parts: raw, treated at 56.5 °C for 30 min, treated at 62.5 °C for 30 min. The results showed that the availability of sulfur amino acids and free taurine is the same after heat treatment, whereas milk processing increased positively the levels of free glutamic acid and glutamine, but there is significance only for glutamine. The mean quantities of considered amino acids were similar in milk treated at the recommended pasteurization temperature (30 min at 62.5 °C) and at 56.5 ° for 30 min.

Characterization of transgenic poplar with ectopic expression of pine cytosolic glutamine synthetase under conditions of varying nitrogen availability

The present study addresses the hypothesis that enhanced expression of glutamine synthetase (GS) in transgenic poplar, characterized by the ectopic expression of pine cytosolic GS, results in an enhanced efficiency of nitrogen (N) assimilation and enhanced growth. Transgenic and control poplar were supplied with low and high N levels and the role of ectopic expression of the pine GS in growth and N assimilation was assessed by using amino acid analysis, (15)N enrichment, biochemical analyses, and growth measurements. While leaves of transgenic poplar contained 85% less (P < 0.01) free ammonium than leaves of nontransgenic control plants, leaves of transgenics showed increases in the levels of free glutamine and total free amino acids. Transgenic poplar lines also displayed significant increases in growth parameters when compared with controls grown under both low (0.3 mm) and high (10 mm) nitrate conditions. Furthermore, (15)N-enrichment experiments showed that 27% more (P < 0.05) (15)N was incorporated into structural compounds in transgenic lines than in nontransgenic controls. Using the methods described here, we present direct evidence for increased N assimilation efficiency and growth in GS transgenic lines.

Allele-specific conditional destabilization of glutamine repeat mRNAs.

Several late-onset neurological diseases are caused by the inheritance of an expanded CAG repeat coding for polyglutamine. To date there is no effective means of halting the progression of these diseases, and their underlying molecular mechanisms remain a mystery. Strategies designed to specifically reduce the levels of long repeat mRNA might provide an effective therapy for these diseases. An emphasis on allele specificity is necessary to avoid the potential toxicities associated with reduction of expression. The experiments described here are based on the relationship between translation and mRNA stability and the idea that translation of a repeated codon might be extremely sensitive to reductions in levels of cognate aminoacylated tRNA. Consistent with this hypothesis, we have discovered that reduced glutamine concentration destabilizes mRNAs coding for long glutamine repeats while sparing short repeat versions of the same mRNAs. These results suggest therapy might be attained with existing compounds or environmental conditions known to decrease free glutamine levels.

Glutamine metabolism in uricotelic species: variation in skeletal muscle glutamine synthetase, glutaminase, glutamine levels and rates of protein synthesis

High intracellular glutamine levels have been implicated in promoting net protein synthesis and accretion in mammalian skeletal muscle. Little is known regarding glutamine metabolism in uricotelic species but chicken breast muscle exhibits high rates of protein accretion and would be predicted to maintain high glutamine levels. However, chicken breast muscle expresses high glutaminase activity and here we report that chicken breast muscle also expresses low glutamine synthetase activity (0.07±0.01 U/g) when compared to leg muscle (0.50±0.04 U/g). Free glutamine levels were 1.38±0.09 and 9.69±0.12 nmol/mg wet weight in breast and leg muscles of fed chickens, respectively. Glutamine levels were also lower in dove breast muscle (4.82±0.35 nmol/mg wet weight) when compared to leg muscle (16.2±1.0 nmol/mg wet weight) and much lower (1.80±0.46 nmol/mg wet weight) in lizard leg muscle. In fed chickens, rates of fractional protein synthesis were higher in leg than in breast muscle, and starvation (48 h) resulted in a decrease in both glutamine content and rate of protein synthesis in leg muscle. Thus, although tissue-specific glutamine metabolism in uricotelic species differs markedly from that in ureotelic animals, differences in rates of skeletal muscle protein synthesis are associated with corresponding differences in intramuscular glutamine content.

Skeletal muscle protein mobilization during the progression of lactation

To investigate changes in muscle metabolism during lactation, serial biopsy of the triceps brachii was conducted in first-parity sows subjected to three degrees of selective protein mobilization through restriction of dietary protein intake (see Clowes EJ, Aherne FX, Foxcroft GR, and Baracos VE. J Anim Sci 81: 753-764, 2003). Muscle biopsies were taken 7 days before parturition and at 12 and 23 days of lactation. The following changes occurred after parturition, were progressive, and were significantly magnified in animals under the greatest degree of dietary protein restriction and hence of protein mobilization. Decreased RNA-to-DNA ratio (capacity for protein synthesis) was observed. The presence of increased expression of several elements of the ubiquitin proteasome proteolytic pathway suggested a robust catabolic response. However, as lactation progressed, and especially under conditions of increased dietary protein restriction, protein mobilization increased, muscle RNA-to-DNA ratio fell further, protease gene expression continued to rise, tissue free glutamine levels rose dramatically, and essential amino acid levels, especially branched-chain amino acids and threonine, fell to below prepartum levels.

Glutamine in commercial liquid nutritional products.

Total glutamine concentrations in commercial nutritional products have been determined by enzymatic hydrolysis followed by HPLC quantification of free glutamine and free pyroglutamic acid. Hydrolysis was accomplished by a published three-enzyme (Pronase, leucine aminopeptidase, prolidase), 20-h/37 degrees C digestion. Glutamine was determined as its FMOC derivative by reverse phase HPLC-fluorescence, and pyroglutamic acid was determined directly by organic acid HPLC-UV. Approximately 4.11% of the released glutamine is converted to pyroglutamic acid during the 20-h digestion. Experimental ratios of enzyme hydrolysis glutamine to acid hydrolysis glutamic acid + glutamine + pyroglutamic acid (GLX) indicate that the method recovers >90% of the protein-bound glutamine. The nutritional products with casein dominant intact protein systems typically deliver >9 g of glutamine/100 g of protein, or approximately 40 g of glutamine/100 g of GLX.

Absorption of enterally administered N-acetyl-l-glutamine versus glutamine in pigs

Background & aims: Glutamine instability in liquid media suggests that evaluation of reasonable enteral nutrition sources of glutamine is needed. N-acetyl-l-glutamine offers no instability and no intolerance problems. This research was conducted to study the absorption and apparent digestibility of glutamine versus N-acetyl-l-glutamine.Methods: Two pig models were used. (1) In a clamped jejunal loop experiment, we measured the concentrations of glutamine and N-acetyl-l-glutamine in the intestinal infused solutions, intestinal mucosa, and portal and peripheral blood. (2) In a feeding experiment, we determined their apparent digestibility.Results: N-acetyl-l-glutamine (∼76%) was slightly less absorbed than glutamine (∼85%) from the intestinal lumen into mucosa, where it was not detected as intact molecule, suggesting almost complete hydrolysis during absorption. Virtually no intact N-acetyl-l-glutamine was observed in the blood compartments; glutamine from lumenal N-acetyl-l-glutamine had the same behavior as that from lumenal-free glutamine in portal and peripheral blood. The apparent ileal digestibility of N-acetyl-l-glutamine was lower than that of free glutamine, as N-acetyl-l-glutamine was probably retained in the intestinal lumen to a greater extent than glutamine.Conclusion: N-acetyl-l-glutamine appeared to be a good candidate for glutamine fortification of enteral nutrition formulas.

Herbicidal pyridyl derivatives of aminomethylene-bisphosphonic acid inhibit plant glutamine synthetase.

A series of aminomethylene-bisphosphonic acid derivatives, previously synthesized and shown to be endowed with herbicidal properties, were evaluated as potential inhibitors of plant glutamine synthetase. The cytosolic form of the enzyme was partially purified from rice cultured cells and assayed in the presence of millimolar concentrations of the compounds by means of three different assay methods, respectively measuring the hemibiosynthetic, the transferase, and the full biosynthetic reactions. Several compounds were found to exert a remarkable inhibition, with I(50) values similar to those obtained under the same conditions with a well-established inhibitor of glutamine synthetase, the herbicide phosphinothricin. Contrary to the reference compound, enzyme kinetics accounted for a reversible inhibition mechanism. The biological activity of the most active derivatives was further characterized by measuring free glutamine levels in cell suspension rice cultures following treatment with the inhibitors. Results confirmed their ability to interfere in vivo with nitrogen metabolism. A preliminary analysis of structure-activity relationship allowed it to be hypothesized that steric rather than electronic factors are responsible for the inhibitory potential of these compounds.

De novo glutamine synthesis induced by corticosteroids in vivo in rats is secondary to weight loss

Introduction: Corticosteroid treatment affects muscle protein and glutamine metabolism. In the present study we aimed to clarify to what extent anorexia, weight loss and corticosteroids determine protein and glutamine metabolism in muscle. Methods: The study was performed in Wistar rats (300–350 g, n=40) given triamcinolone (0.25 mg/kg/day i.m.) treatment (CS group) for 14 days, sham treated free fed (FF group), sham treated pair fed (PF group) and sham treated pair weight (PW group). In vivo protein and glutamine turnover were measured using l-[2,6-3H]phenylalanine and l-[3,4-3H]glurtamine as tracer in a three compartment model across the hindquarter. Results: Corticosteroid treatment decreased total body weight to a greater extent than can be explained by decreased food intake only, justifying the need for pair weight controls. Muscle weight loss was relatively greater in the corticosteroid treated rats than in the pair weight controls indicating specific corticosteroid induced changes in muscle protein metabolism. Pair weight rats increased muscle net protein breakdown rates from −5±3 nmol×100 g body weight −1×min −1 to −15±3 nmol×100 g body weight −1×min −1 ( P<0.05 vs FF). In the corticosteroid treated rats net protein breakdown rates increased to −22±4 nmol×100 g body weight −1×min −1 ( P<0.01 CS vs FF/PF) Net protein breakdown in corticosteroid treated rats was accompanied by increased glutamine efflux from the hindquarter ( P<0.05, CS vs FF/PF/PW). The latter could predominantly be explained by de novo synthesis. Furthermore, corticosteroid treatment induced a loss of plasma to free muscle glutamine gradient indicating down regulation of glutamine membrane transport rates into muscle. This effect was, however, similar in the pair weight control group and can thus be fully accounted for by the muscle weight loss. Conclusion: Two weeks treatment with triamcinolone increases net in vivo protein breakdown of muscle directly and indirectly due to secondary weight loss and decreased food intake. The amino acid residues are used for glutamine de novo synthesis which is exported from muscle to visceral organs by down regulation of glutamine transport systems. These changes were in majority related to muscle weight loss.

Effects on skeletal muscle of intravenous glutamine supplementation to ICU patients

To evaluate the effect of four doses of intravenous glutamine supplementation on skeletal muscle metabolism. A prospective, blinded, randomized study. The general Intensive Care Unit (ICU) of a university hospital. ICU patients with multiple organ failure (n=40), who were expected to stay in the unit for more than five days. Patients received 0, 0.28, 0.57 or 0.86 g of glutamine per kg bodyweight per day intravenously for five days as part of an isocaloric, isonitrogenous and isovolumetric diet. Plasma glutamine concentration responded to glutamine supplementation with normalization of plasma levels in a dose-dependent way, while free muscle glutamine concentration, as well as muscle protein synthesis and muscle protein content, did not change significantly. Intravenous glutamine supplementation to ICU patients for a period of five days resulted in normalization of plasma glutamine concentrations in a dose-dependent way whereas muscle glutamine concentrations were unaffected.

Effects of distance running and subsequent intake of glutamine rich peptide on biomedical parameters of male Japanese athletes

Plasma glutamine concentration is considered to be an indicator for immune system, and its kinetics and effects of glutamine supplementation have been widely investigated under various conditions. However most of the investigations were performed using Caucasian subjects and free glutamine as a glutamine source, and there is limited information for Japanese subjects and the efficacy of peptide-bonded glutamine. The purposes of this work were to assess the kinetics of glutamine and other biomedical parameters during and after prolonged exercises and effects of post-exercise administration of glutamine peptide (wheat gluten hydrolysate) in male Japanese athletes. The participants performed a half-marathon and a 45-km running. Glutamine peptide (c.a. 0.2 g Gln/kg bodyweight) was administered after the exercise. Plasma branched chain amino acids (BCAA) decreased after both exercises, while a decrease in glutamine was observed only after 45-km run. Intake of glutamine peptide increased plasma glutamine and BCAA, and decreased Trp/BCAA ratio both after the half marathon and the 45-km run.