L-Glutamine

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Paul A M Van Leeuwen - One of the best experts on this subject based on the ideXlab platform.

  • enteral glutamine administration in critically ill nonseptic patients does not trigger arginine synthesis
    Journal of Nutrition and Metabolism, 2016
    Co-Authors: M Vermeulen, Saskia J H Brinkmann, Nikki Buijs, Albertus Beishuizen, Alexander P J Houdijk, Johannes B Van Goudoever, Paul A M Van Leeuwen
    Abstract:

    Glutamine supplementation in specific groups of critically ill patients results in favourable clinical outcome. Enhancement of citrulline and arginine synthesis by glutamine could serve as a potential mechanism. However, while receiving optimal enteral nutrition, uptake and enteral metabolism of glutamine in critically ill patients remain unknown. Therefore we investigated the effect of a therapeutically relevant dose of L-Glutamine on synthesis of L-citrulline and subsequent L-arginine in this group. Ten versus ten critically ill patients receiving full enteral nutrition, or isocaloric isonitrogenous enteral nutrition including 0.5 g/kg L-alanyl-L-Glutamine, were studied using stable isotopes. A cross-over design using intravenous and enteral tracers enabled splanchnic extraction (SE) calculations. Endogenous rate of appearance and SE of glutamine citrulline and arginine was not different (SE controls versus alanyL-Glutamine: glutamine 48 and 48%, citrulline 33 versus 45%, and arginine 45 versus 42%). Turnover from glutamine to citrulline and arginine was not higher in glutamine-administered patients. In critically ill nonseptic patients receiving adequate nutrition and a relevant dose of glutamine there was no extra citrulline or arginine synthesis and glutamine SE was not increased. This suggests that for arginine synthesis enhancement there is no need for an additional dose of glutamine when this population is adequately fed. This trial is registered with NTR2285.

  • enteral administration of alanyl 2 15n glutamine contributes more to the de novo synthesis of arginine than does intravenous infusion of the dipeptide in humans
    The American Journal of Clinical Nutrition, 2009
    Co-Authors: Gerdien C Ligthartmelis, Marcel C G Van De Poll, Petra G Boelens, Cors Van Schaik, Jeanpascal De Bandt, Nicolaas E P Deutz, Cornelis H C Dejong, M Vermeulen, Paul A M Van Leeuwen
    Abstract:

    BACKGROUND: We previously confirmed in humans the existence of a pathway of glutamine into citrulline and arginine, which is preferentially stimulated by luminally provided glutamine. However, because glutamine is unstable, we tested this pathway with a stable dipeptide of glutamine. OBJECTIVES: The objectives were to explore whether alanyL-Glutamine contributes to the synthesis of arginine in humans and whether this depends on the route of administration. DESIGN: The study was conducted under postabsorptive conditions during surgery. Sixteen patients received alanyl-[2-(15)N]glutamine enterally or intravenously together with intravenously administered stable-isotope tracers of citrulline and arginine. Blood was collected from an artery, the portal vein, a hepatic vein, and the right renal vein. Arterial and venous enrichments and (tracer) net balances of alanyL-Glutamine and glutamine, citrulline, and arginine across the portal drained viscera, liver, and kidneys were determined. Parametric tests were used to test results (mean +/- SEM). P < 0.05 was considered significant. RESULTS: Twice as much exogenous glutamine was used for the synthesis of citrulline when alanyL-Glutamine was provided enterally (5.9 +/- 0.6%) than when provided intravenously (2.8 +/- 0.3%) (P < 0.01). Consequently, twice as much exogenous glutamine was used for the synthesis of arginine when alanyL-Glutamine was provided enterally (5 +/- 0.7%) than when provided intravenously (2.4 +/- 0.2%) (P < 0.01). However, results at the organ level did not explain the differences due to route of administration. CONCLUSIONS: AlanyL-Glutamine contributes to the de novo synthesis of arginine, especially when provided enterally. A stable-isotope study using a therapeutic dose of alanyL-Glutamine is needed to investigate the clinical implications of this finding.

M Vermeulen - One of the best experts on this subject based on the ideXlab platform.

  • enteral glutamine administration in critically ill nonseptic patients does not trigger arginine synthesis
    Journal of Nutrition and Metabolism, 2016
    Co-Authors: M Vermeulen, Saskia J H Brinkmann, Nikki Buijs, Albertus Beishuizen, Alexander P J Houdijk, Johannes B Van Goudoever, Paul A M Van Leeuwen
    Abstract:

    Glutamine supplementation in specific groups of critically ill patients results in favourable clinical outcome. Enhancement of citrulline and arginine synthesis by glutamine could serve as a potential mechanism. However, while receiving optimal enteral nutrition, uptake and enteral metabolism of glutamine in critically ill patients remain unknown. Therefore we investigated the effect of a therapeutically relevant dose of L-Glutamine on synthesis of L-citrulline and subsequent L-arginine in this group. Ten versus ten critically ill patients receiving full enteral nutrition, or isocaloric isonitrogenous enteral nutrition including 0.5 g/kg L-alanyl-L-Glutamine, were studied using stable isotopes. A cross-over design using intravenous and enteral tracers enabled splanchnic extraction (SE) calculations. Endogenous rate of appearance and SE of glutamine citrulline and arginine was not different (SE controls versus alanyL-Glutamine: glutamine 48 and 48%, citrulline 33 versus 45%, and arginine 45 versus 42%). Turnover from glutamine to citrulline and arginine was not higher in glutamine-administered patients. In critically ill nonseptic patients receiving adequate nutrition and a relevant dose of glutamine there was no extra citrulline or arginine synthesis and glutamine SE was not increased. This suggests that for arginine synthesis enhancement there is no need for an additional dose of glutamine when this population is adequately fed. This trial is registered with NTR2285.

  • enteral administration of alanyl 2 15n glutamine contributes more to the de novo synthesis of arginine than does intravenous infusion of the dipeptide in humans
    The American Journal of Clinical Nutrition, 2009
    Co-Authors: Gerdien C Ligthartmelis, Marcel C G Van De Poll, Petra G Boelens, Cors Van Schaik, Jeanpascal De Bandt, Nicolaas E P Deutz, Cornelis H C Dejong, M Vermeulen, Paul A M Van Leeuwen
    Abstract:

    BACKGROUND: We previously confirmed in humans the existence of a pathway of glutamine into citrulline and arginine, which is preferentially stimulated by luminally provided glutamine. However, because glutamine is unstable, we tested this pathway with a stable dipeptide of glutamine. OBJECTIVES: The objectives were to explore whether alanyL-Glutamine contributes to the synthesis of arginine in humans and whether this depends on the route of administration. DESIGN: The study was conducted under postabsorptive conditions during surgery. Sixteen patients received alanyl-[2-(15)N]glutamine enterally or intravenously together with intravenously administered stable-isotope tracers of citrulline and arginine. Blood was collected from an artery, the portal vein, a hepatic vein, and the right renal vein. Arterial and venous enrichments and (tracer) net balances of alanyL-Glutamine and glutamine, citrulline, and arginine across the portal drained viscera, liver, and kidneys were determined. Parametric tests were used to test results (mean +/- SEM). P < 0.05 was considered significant. RESULTS: Twice as much exogenous glutamine was used for the synthesis of citrulline when alanyL-Glutamine was provided enterally (5.9 +/- 0.6%) than when provided intravenously (2.8 +/- 0.3%) (P < 0.01). Consequently, twice as much exogenous glutamine was used for the synthesis of arginine when alanyL-Glutamine was provided enterally (5 +/- 0.7%) than when provided intravenously (2.4 +/- 0.2%) (P < 0.01). However, results at the organ level did not explain the differences due to route of administration. CONCLUSIONS: AlanyL-Glutamine contributes to the de novo synthesis of arginine, especially when provided enterally. A stable-isotope study using a therapeutic dose of alanyL-Glutamine is needed to investigate the clinical implications of this finding.

Phyllis I Hanson - One of the best experts on this subject based on the ideXlab platform.

  • snare complex zero layer residues are not critical for n ethylmaleimide sensitive factor mediated disassembly
    Journal of Biological Chemistry, 2006
    Co-Authors: Joshua M Lauer, Michael L Nonet, Seema Dalal, Karla E Marz, Phyllis I Hanson
    Abstract:

    Membrane-anchored SNAREs assemble into SNARE complexes that bring membranes together to promote fusion. SNARE complexes are parallel four-helix bundles stabilized in part by hydrophobic interactions within their core. At the center of SNARE complexes is a distinctive zero layer that consists of one arginine and three glutamines. This zero layer is thought to play a special role in the biology of the SNARE complex. One proposal is that the polar residues of the zero layer enable N-ethylmaleimide-sensitive factor (NSF)-mediated SNARE complex disassembly. Here, we studied the effects of manipulating the zero layer of the well studied synaptic SNARE complex in vitro and in vivo. Using a fluorescence-based assay to follow SNARE complex disassembly in real time, we found that the maximal rate at which NSF disassembles complexes was unaffected by mutations in the zero layer, including single replacement of the syntaxin glutamine with arginine as well as multiple replacement of all four layer residues with non-polar amino acids. To determine whether syntaxin with arginine instead of glutamine in its zero layer can support SNARE function in vivo, we introduced it as a transgene into a Caenorhabditis elegans syntaxin-null strain. Mutant syntaxin rescued viability and locomotory defects similarly to wild-type syntaxin, demonstrating that SNARE complexes with two glutamines and two arginines in the zero layer can support neurotransmission. These findings show that residues of the zero layer do not play an essential role in NSF-mediated disassembly.

Patrick Brennwald - One of the best experts on this subject based on the ideXlab platform.

  • testing the 3q 1r rule mutational analysis of the ionic zero layer in the yeast exocytic snare complex reveals no requirement for arginine
    Molecular Biology of the Cell, 2000
    Co-Authors: Luba Katz, Patrick Brennwald
    Abstract:

    The crystal structure of the synaptic SNARE complex reveals a parallel four-helix coiled-coil arrangement; buried in the hydrophobic core of the complex is an unusual ionic layer composed of three glutamines and one arginine, each provided by a separate α-helix. The presence of glutamine or arginine residues in this position is highly conserved across the t- and v-SNARE families, and it was recently suggested that a 3Q:1R ratio is likely to be a general feature common to all SNARE complexes. In this study, we have used genetic and biochemical assays to test this prediction with the yeast exocytic SNARE complex. We have determined that the relative position of Qs and Rs within the layer is not critical for biological activity and that Q-to-R substitutions in the layer reduce complex stability and result in lethal or conditional lethal growth defects. Surprisingly, SNARE complexes composed of four glutamines are fully functional for assembly in vitro and exocytic function in vivo. We conclude that the 3Q:1R layer composition is not required within the yeast exocytic SNARE complex because complexes containing four Q residues in the ionic layer appear by all criteria to be functionally equivalent. The unexpected flexibility of this layer suggests that there is no strict requirement for the 3Q:1R combination and that the SNARE complexes at other stages of transport may be composed entirely of Q-SNAREs or other noncanonical combinations.

Shaw S. Wang - One of the best experts on this subject based on the ideXlab platform.

  • role of glutamine in hybridoma cell culture effects on cell growth antibody production and cell metabolism
    Enzyme and Microbial Technology, 1995
    Co-Authors: Yeonho Jeong, Shaw S. Wang
    Abstract:

    Abstract The effects of glutamine on cell growth kinetics, monoclonal antibody productivity, and cell metabolism of hybridoma cells were investigated. The mouse-mouse hybridoma cell line V111 H-8, which produces mouse immunoglobulin (IgG 2a ) was used as a model system. Glutamine showed a Monod-type effect on specific cell growth rate with a very small Monod constant of 0.089 (m m ). A reciprocal relationship between initial glutamine concentration and specific cell death rate was observed. Monoclonal antibody (MAb) production was a strong function of glutamine concentration. Glutamine enhanced MAb production not only by stimulation of cell growth, but also by increasing the specific MAb productivity. Increasing glutamine concentration stimulated specific glutamine consumption rate and specific ammonium ion production rate. The specific glucose consumption rate decreased with increasing glutamine concentration up from 0 to 0.1 n m , and then increased. The specific lactate production rate decreased as glutamine concentration decreased.