scholarly journals Simultaneous Determination of the Rates of the TCA Cycle, Glucose Utilization, α-Ketoglutarate/Glutamate Exchange, and Glutamine Synthesis in Human Brain by NMR

1995 ◽  
Vol 15 (1) ◽  
pp. 12-25 ◽  
Author(s):  
Graeme F. Mason ◽  
Rolf Gruetter ◽  
Douglas L. Rothman ◽  
Kevin L. Behar ◽  
Robert G. Shulman ◽  
...  
Keyword(s):  
Human Brain ◽  
Glucose Consumption ◽  
Tca Cycle ◽  
High Rate ◽  
Cycle Rate ◽  
The Tca Cycle ◽  
Glutamine Synthesis ◽  
Physiological Values

13C isotopic tracer data previously obtained by 13C nuclear magnetic resonance in the human brain in vivo were analyzed using a mathematical model to determine metabolic rates in a region of the human neocortex. The tricarboxylic acid (TCA) cycle rate was 0.73 ± 0.19 μmol min−1 g−1 (mean ± SD; n = 4). The standard deviation reflects primarily intersubject variation, since individual uncertainties were low. The rate of α-ketoglutarate/glutamate exchange was 57 ± 26 μmol min−1 g−1 ( n = 3), which is much greater than the TCA cycle rate; the high rate indicates that α-ketoglutarate and glutamate are in rapid exchange and can be treated as a single combined kinetic pool. The rate of synthesis of glutamine from glutamate was 0.47 μmol min−1 g−1 ( n = 4), with 95% confidence limits of 0.139 and 3.094 μmol min−1 g−1; individual uncertainties were biased heavily toward high synthesis rates. From the TCA cycle rate the brain oxygen consumption was estimated to be 2.14 ± 0.48 μmol min−1 g−1 (5.07 ± 1.14 ml 100 g−1 min−1; n = 4), and the rate of brain glucose consumption was calculated to be 0.37 ± 0.08 μmol min−1 g−1 ( n = 4). The sensitivity of the model to the assumptions made was evaluated, and the calculated values were found to be unchanged as long as the assumptions remained near reported physiological values.

scholarly journals NMR Determination of the TCA Cycle Rate and α-Ketoglutarate/Glutamate Exchange Rate in Rat Brain

1992 ◽  
Vol 12 (3) ◽  
pp. 434-447 ◽  
Author(s):  
Graeme F. Mason ◽  
Douglas L. Rothman ◽  
Kevin L. Behar ◽  
Robert G. Shulman
Keyword(s):  
Exchange Rate ◽  
Rat Brain ◽  
Tca Cycle ◽  
Isotopic Labeling ◽  
Cycle Rate ◽  
The Tca Cycle ◽  
The Difference ◽  
Tca Cycle Intermediates

A mathematical model of cerebral glucose metabolism was developed to analyze the isotopic labeling of carbon atoms C4 and C3 of glutamate following an intravenous infusion of [1-13C]glucose. The model consists of a series of coupled metabolic pools representing glucose, glycolytic intermediates, tricarboxylic acid (TCA) cycle intermediates, glutamate, aspartate, and glutamine. Based on the rate of 13C isotopic labeling of glutamate C4 measured in a previous study, the TCA cycle rate in rat brain was determined to be 1.58 ± 0.41 μmol min−1 g−1 (mean ± SD, n = 5). Analysis of the difference between the rates of isotopic enrichment of glutamate C4 and C3 permitted the rate of exchange between α-ketoglutarate (α-KG) and glutamate to be assessed in vivo. In rat brain, the exchange rate between α-KG and glutamate is between 89 ± 35 and 126 ± 22 times faster than the TCA cycle rate (mean ± SD, n = 4). The sensitivity of the calculated value of the TCA cycle rate to other metabolic fluxes and to concentrations of glycolytic and TCA cycle intermediates was tested and found to be small.

scholarly journals Mitochondrial Mistranslation in Brain Provokes a Metabolic Response Which Mitigates the Age-Associated Decline in Mitochondrial Gene Expression

2021 ◽  
Vol 22 (5) ◽  
pp. 2746
Author(s):  
Dimitri Shcherbakov ◽  
Reda Juskeviciene ◽  
Adrián Cortés Sanchón ◽  
Margarita Brilkova ◽  
Hubert Rehrauer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Metabolic Response ◽  
Mitochondrial Gene ◽  
Tca Cycle ◽  
Brain Mitochondria ◽  
Mitochondrial Gene Expression ◽  
Rna Seq ◽  
The Tca Cycle ◽  
Neurological Phenotype

Mitochondrial misreading, conferred by mutation V338Y in mitoribosomal protein Mrps5, in-vivo is associated with a subtle neurological phenotype. Brain mitochondria of homozygous knock-in mutant Mrps5V338Y/V338Y mice show decreased oxygen consumption and reduced ATP levels. Using a combination of unbiased RNA-Seq with untargeted metabolomics, we here demonstrate a concerted response, which alleviates the impaired functionality of OXPHOS complexes in Mrps5 mutant mice. This concerted response mitigates the age-associated decline in mitochondrial gene expression and compensates for impaired respiration by transcriptional upregulation of OXPHOS components together with anaplerotic replenishment of the TCA cycle (pyruvate, 2-ketoglutarate).

TCA cycle flux estimates from NMR- and GC-MS-determined [13C]glutamate isotopomers in liver

1997 ◽  
Vol 272 (6) ◽  
pp. C2049-C2062 ◽  
Author(s):  
J. A. Vogt ◽  
D. M. Yarmush ◽  
Y. M. Yu ◽  
C. Zupke ◽  
A. J. Fischman ◽  
...  
Keyword(s):  
Tca Cycle ◽  
Gas Chromatography Mass Spectrometry ◽  
Flow Rates ◽  
13C Nuclear Magnetic Resonance ◽  
Two Factors ◽  
Subsequent Measurement ◽  
System 1 ◽  
Relative Flow

Infusion of 13C-labeled lactate into rabbits and the subsequent measurement of glutamate isotopomers by 13C nuclear magnetic resonance (NMR) spectroscopy enables one to calculate relative flow rates associated with the tricarboxylic acid (TCA) cycle, albeit with a lower precision than one would obtain using a perfused organ. Two factors contribute to the lower precision in the determination of relative flow rates for the in vivo system: 1) a poorly defined pyruvate input and 2) low levels of 13C-enriched oxaloacetate and acetyl-CoA isotopomers, which give rise to weaker glutamate isotopomer NMR signals. To help overcome these limitations, we introduce a procedure to 1) include experimental data from gas chromatography-mass spectrometry (GC-MS) and 2) account for the uncertainty in the labeling of the input to pyruvate by creating the labeling as a measurement that is subject to measurement error. The effects of the uncertainties in the input labeling, NMR data, and MS data are evaluated via a Monte Carlo method. The change in the precision of the relative fluxes for the cases of high/low NMR and high/low MS precision is given. An uncertainty in the lactate measurements of up to 10% does not add significantly to the imprecision of the relative flow rates.

Genomic and metabolomic analysis of step-wise malignant transformation in human skin fibroblasts

2019 ◽  
Vol 41 (5) ◽  
pp. 656-665
Author(s):  
Anastasia Kariagina ◽  
Sophia Y Lunt ◽  
J Justin McCormick
Keyword(s):  
Malignant Transformation ◽  
Human Fibroblasts ◽  
Glucose Consumption ◽  
Tca Cycle ◽  
Transformed Cells ◽  
Aminooxyacetic Acid ◽  
Malignant Cells ◽  
The Impact

Abstract Metabolic changes accompanying a step-wise malignant transformation was investigated using a syngeneic lineage of human fibroblasts. Cell immortalization was associated with minor alterations in metabolism. Consecutive loss of cell cycle inhibition in immortalized cells resulted in increased levels of oxidative phosphorylation (OXPHOS). Overexpression of the H-Ras oncoprotein produced cells forming sarcomas in athymic mice. These transformed cells exhibited increased glucose consumption, glycolysis and a further increase in OXPHOS. Because of the markedly increased OXPHOS in transformed cells, the impact of a transaminase inhibitor, aminooxyacetic acid (AOA), which decreases glutamine influx to the tricarboxylic acid (TCA) cycle, was tested. Indeed, AOA significantly decreased proliferation of malignantly transformed fibroblasts and fibrosarcoma-derived cells in vitro and in vivo. AOA also decreased proliferation of cells susceptible to malignant transformation. Metabolomic studies in normal and transformed cells indicated that, in addition to the anticipated effect on the TCA cycle, AOA decreased production of nucleotides adenosine triphosphate (ATP) and uridine monophosphate. Exogenous nucleotides partially rescued decreased proliferation of the malignant cells treated with AOA. Our data indicate that AOA blocks several metabolic pathways essential for growth of malignant cells. Therefore, OXPHOS may provide important therapeutic targets for treatment of sarcoma.

scholarly journals Proteomic Analysis of Beef Tenderloin and Flank Assessed Using an Isobaric Tag for Relative and Absolute Quantitation (iTRAQ)

Animals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 150
Author(s):  
Zhaomin Lei ◽  
Jianping Wu ◽  
Deyin Zhang ◽  
Ting Liu ◽  
Shengguo Zhao ◽  
...  
Keyword(s):  
Proteomic Analysis ◽  
Expression Patterns ◽  
Tca Cycle ◽  
Absolute Quantification ◽  
Absolute Quantitation ◽  
Oxidation Reduction ◽  
The Tca Cycle ◽  
Isobaric Tag ◽  
Isobaric Tags

Herein, we performed a proteomic analysis of tenderloin and flank steaks from Simmental cattle using the isobaric tags for a relative and absolute quantification (iTRAQ) approach. We identified 17 amino acids in both steaks, and Gly, Cys, Ile, Lys, and Pro differed most in abundance between the steak types (p < 0.05). A comparison of the expression patterns in steaks revealed 128 differentially expressed proteins (DEPs), of which 44 were up-regulated and 84 were down-regulated. Furthermore, 27 DEPs (p < 0.05) were subjected to gene ontology (GO) analysis, and many were found to be related to oxidation-reduction, metabolism, hydrogen ion transmembrane transport, transport, the tricarboxylic acid (TCA) cycle, mitochondrial electron transport, and the conversion of nicotinamide adenine dinucleotide (NADH) to ubiquinone. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis also implicated these DEPs in various signalling pathways, including oxidative phosphorylation, cardiac muscle contraction, the TCA cycle, biosynthesis, and the metabolism. These findings provide a new insight into key proteins involved in the determination of amino acid composition in beef.

scholarly journals Bovine Oviduct Epithelial Cell-Derived Culture Media and Exosomes Improve Mitochondrial Health by Restoring Metabolic Flux during Pre-Implantation Development

2020 ◽  
Vol 21 (20) ◽  
pp. 7589
Author(s):  
Tabinda Sidrat ◽  
Abdul Aziz Khan ◽  
Myeon-Don Joo ◽  
Yiran Wei ◽  
Kyeong-Lim Lee ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Embryonic Development ◽  
Metabolic Flux ◽  
Culture Media ◽  
Tca Cycle ◽  
Fine Tuning ◽  
The Tca Cycle ◽  
Oviduct Epithelial Cell

Oviduct flushing is enriched by a wide variety of nutrients that guide the 3–4 days journey of pre-implantation embryo through the oviduct as it develops into a competent blastocyst (BL). However, little is known about the specific requirement and role of these nutrients that orchestrate the early stages of embryonic development. In this study, we aimed to characterize the effect of in vitro-derived bovine oviduct epithelial cell (BOECs) secretion that mimics the in vivo oviduct micro-fluid like environment, which allows successful embryonic development. In this study, the addition of an in vitro derived BOECs-condition media (CM) and its isolated exosomes (Exo) significantly enhances the quality and development of BL, while the hatching ability of BLs was found to be high (48.8%) in the BOECs-Exo supplemented group. Surprisingly, BOECs-Exo have a dynamic effect on modulating the embryonic metabolism by restoring the pyruvate flux into TCA-cycle. Our analysis reveals that Exo treatment significantly upregulates the pyruvate dehydrogenase (PDH) and glutamate dehydrogenase (GLUD1) expression, required for metabolic fine-tuning of the TCA-cycle in the developing embryos. Exo treatment increases the influx into TCA-cycle by strongly suppressing the PDH and GLUD1 upstream inhibitors, i.e., PDK4 and SIRT4. Improvement of TCA-cycle function was further accompanied by higher metabolic activity of mitochondria in BOECs-CM and Exo in vitro embryos. Our study uncovered, for the first time, the possible mechanism of BOECs-derived secretion in re-establishing the TCA-cycle flux by the utilization of available nutrients and highlighted the importance of pyruvate in supporting bovine in vitro embryonic development.

scholarly journals Evidence for reverse flux through pyruvate kinase in skeletal muscle

2009 ◽  
Vol 296 (4) ◽  
pp. E748-E757 ◽  
Author(s):  
Eunsook S. Jin ◽  
A. Dean Sherry ◽  
Craig R. Malloy
Keyword(s):  
Skeletal Muscle ◽  
Glucose Production ◽  
Tca Cycle ◽  
Hepatic Glycogen ◽  
Direct Transfer ◽  
The Tca Cycle ◽  
Tca Cycle Intermediates ◽  
Minced Muscle ◽  
Labeling Pattern

Conversion of lactate to glucose was examined in myotubes, minced muscle tissue, and rats exposed to 2H2O or 13C-enriched substrates. Myotubes or minced skeletal muscle incubated with [U-13C3]lactate released small amounts of [1,2,3-13C3]- or [4,5,6-13C3]glucose. This labeling pattern is consistent with direct transfer from lactate to glucose without randomization in the tricarboxylic acid (TCA) cycle. After exposure of incubated muscle to 2H2O, [U-13C3]lactate, glucose, and glutamine, there was minimal release of synthesized glucose to the medium based on a low level of 2H enrichment in medium glucose but 50- to 100-fold greater 2H enrichment in glucosyl units from glycogen. The 13C enrichment pattern in glycogen from incubated skeletal muscle was consistent only with direct transfer of lactate to glucose without exchange in TCA cycle intermediates. 13C nuclear magnetic resonance (NMR) spectra of glutamate from the same tissue showed flux from lactate through pyruvate dehydrogenase but not flux through pyruvate carboxylase into the TCA cycle. Carbon from an alternative substrate for glucose production that requires metabolism through the TCA cycle, propionate, did not enter glycogen, suggesting that TCA cycle intermediates do not exchange with phospho enolpyruvate. In vivo, the 13C labeling patterns in hepatic glycogen and plasma glucose after administration of [U-13C3]lactate did not differ significantly. However, skeletal muscle glycogen was substantially enriched in [1,2,3-13C3]- and [4,5,6-13C3]glucose units that could only occur through skeletal muscle glyconeogenesis rather than glycogenesis. Lactate serves as a substrate for glyconeogenesis in vivo without exchange into symmetric intermediates of the TCA cycle.

A proposed method for in vivo determination of lithium in human brain

1985 ◽  
Vol 30 (11) ◽  
pp. 1225-1236 ◽  
Author(s):  
D Vartsky ◽  
A LoMonte ◽  
K J Ellis ◽  
S Yasumura ◽  
S H Cohn
Keyword(s):  
Human Brain

scholarly journals In vivo assessment of glutamine anaplerosis into the TCA cycle in human pre-malignant and malignant clonal plasma cells

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Wilson I. Gonsalves ◽  
Jin Sung Jang ◽  
Erik Jessen ◽  
Taro Hitosugi ◽  
Laura A. Evans ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mononuclear Cells ◽  
Plasma Cells ◽  
Bone Marrow Cells ◽  
Bone Marrow Aspiration ◽  
Tca Cycle ◽  
Link Type ◽  
The Tca Cycle ◽  
Bone Marrow Plasma

Abstract Background Overexpression of c-Myc is required for the progression of pre-malignant plasma cells in monoclonal gammopathy of undetermined significance (MGUS) to malignant plasma cells in multiple myeloma (MM). c-Myc also increases glutamine anaplerosis into the tricarboxylic acid (TCA) cycle within cancer cells. Whether increased glutamine anaplerosis is associated with the progression of pre-malignant to malignant plasma cells is unknown. Methods Human volunteers (N = 7) and patients with MGUS (N = 11) and MM (N = 12) were prospectively recruited to undergo an intravenous infusion of 13C-labeled glutamine followed by a bone marrow aspiration to obtain bone marrow cells and plasma. Results Despite notable heterogeneity, stable isotope-resolved metabolomics (SIRM) revealed that the mean 13C-labeled glutamine anaplerosis into the TCA cycle was higher in malignant compared to pre-malignant bone marrow plasma cells relative to the remainder of their paired bone marrow mononuclear cells. RNA sequencing demonstrated a higher relative mRNA expression of c-Myc and glutamine transporters such as ASCT2 and SN2 in malignant compared to pre-malignant bone marrow plasma cells. Finally, higher quantitative levels of TCA cycle intermediates in the bone marrow plasma differentiated MM from MGUS patients. Conclusion Measurement of the in vivo activity of glutamine anaplerosis into the TCA cycle provides novel insight into the metabolic changes associated with the transformation of pre-malignant plasma cells in MGUS to malignant plasma cells in MM. Trial registration NCT03384108 and NCT03119883

scholarly journals Simplified 13 C metabolic modeling for simplified measurements of cerebral TCA cycle rate in vivo

2009 ◽  
Vol 62 (6) ◽  
pp. 1641-1645 ◽  
Author(s):  
Julien Valette ◽  
Fawzi Boumezbeur ◽  
Philippe Hantraye ◽  
Vincent Lebon
Keyword(s):  
Metabolic Modeling ◽  
Tca Cycle ◽  
Cycle Rate
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