Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent investigations from our and other laboratories indicate that glycogen is a carbon-chain precursor in muscle for the synthesis of TCA cycle intermediates and glutamine. During intense exercise and in conditions of a relative lack of energy (hypoxia, trauma, sepsis) the metabolism of branched-chain amino acids (BCAA) is accelerated in muscle. In the primary BCAA aminotransferase reaction 2-oxoglutarate is used as amino-group acceptor (putting a carbon-drain on the TCA cycle) under formation of glutamate. Glutamate will subsequently react with ammonia, generated in the AMP deaminase reaction or by deamination of amino acids, under formation of glutamine in a reaction catalysed by glutamine synthetase (glutamate + ammonia + ATP--> glutamine + ADP). Muscle glycogen stores may be smaller or less available at high altitude. It is hypothesized that this will lead to premature fatigue (due to both a lack of fuel and of TCA cycle carbon-precursor) and to a reduction in the synthesis rate of glutamine. A chronic reduction in the synthesis rate of glutamine during a long term stay at high altitude on its turn may lead to gut atrophy, bacterial translocation, endotoxemia, muscle protein catabolism and a weakened immune status.
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PMID:Amino acid metabolism, muscular fatigue and muscle wasting. Speculations on adaptations at high altitude. 148 45

During intense exercise there is an augmented production of ammonia and IMP in the exercised muscle that could be related to the establishment of peripheral fatigue. In order to prevent this accumulation, the urea cycle in the liver eliminates ammonia in the form of urea and the skeletal muscle buffers the increase of ammonia via transamination reactions. In the present study we evaluated the effect of arginine, citrulline and ornithine supplementation, intermediates of the urea cycle, on the performance of sedentary and swimming-trained rats submitted to a single bout of exhaustive exercise. We also measured the glycogen content of the soleus and gastrocnemius muscles and of the liver, as well as the plasma concentrations of ammonia, urea, glutamine, glucose and lactate. The results indicate that arginine, citrulline and ornithine supplementation increased the flux of substrate through the reaction catalysed by glutamine synthetase, leading to increased glutamine production after an exhaustive bout of exercise, and of the mechanism involved in ammonia buffering.
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PMID:Effect of arginine, ornithine and citrulline supplementation upon performance and metabolism of trained rats. 1257 27

Oxidative stress, manifested by protein oxidation, lipid peroxidation, DNA oxidation and 3-nitrotyrosine formation, among other indices, is observed in Alzheimer's disease (AD) brain. Amyloid beta-peptide (1-42) [Abeta(1-42)] may be central to the pathogenesis of AD. Our laboratory and others have implicated Abeta(1-42)-induced free radical oxidative stress in the neurodegeneration observed in AD brain. This paper reviews some of these studies from our laboratory. Recently, we showed both in-vitro and in-vivo that methionine residue 35 (Met-35) of Abeta(1-42) was critical to its oxidative stress and neurotoxic properties. Because the C-terminal region of Abeta(1-42) is helical, and invoking the i + 4 rule of helices, we hypothesized that the carboxyl oxygen of lle-31, known to be within a van der Waals distance of the S atom of Met-35, would interact with the latter. This interaction could alter the susceptibility for oxidation of Met-35, i.e. free radical formation. Consistent with this hypothesis, substitution of lle-31 by the helix-breaking amino acid, proline, completely abrogated the oxidative stress and neurotoxic properties of Abeta(1-42). Removal of the Met-35 residue from the lipid bilayer by substitution of the negatively charged Asp for Gly-37 abrogated oxidative stress and neurotoxic properties of Abeta(1-42). The free radical scavenger vitamin E prevented A(beta (1-42)-induced ROS formation, protein oxidation, lipid peroxidation, and neurotoxicity in hippocampal neurons, consistent with our model for Abeta-associated free radical oxidative stress induced neurodegeneration in AD. ApoE, allele 4, is a risk factor for AD. Synaptosomes from apoE knock-out mice are more vulnerable to Abeta-induced oxidative stress (protein oxidation, lipid peroxidation, and ROS generation) than are those from wild-type mice. We also studied synaptosomes from allele-specific human apoE knock-in mice. Brain membranes from human apoE4 mice have greater vulnerability to Abeta(1-42)-induced oxidative stress than brain membranes from apoE2 or E3, assessed by the same indices, consistent with the notion of a coupling of the oxidative environment in AD brain and increased risk of developing this disorder. Using immunoprecipitation of proteins from AD and control brain obtained no longer than 4h PMI, selective oxidized proteins were identified in the AD brain. Creatine kinase (CK) and beta-actin have increased carbonyl groups, an index of protein oxidation, and Glt-1, the principal glutamate transporter, has increased binding of the lipid peroxidation product, 4-hydroxy-2-nonenal (HNE). Abeta inhibits CK and causes lipid peroxidation, leading to HNE formation. Implications of these findings relate to decreased energy utilization, altered assembly of cytoskeletal proteins, and increased excitotoxicity to neurons by glutamate, all reported for AD. Other oxidatively modified proteins have been identified in AD brain by proteomics analysis, and these oxidatively-modified proteins may be related to increased excitotoxicity (glutamine synthetase), aberrant proteasomal degradation of damaged or aggregated proteins (ubiquitin C-terminal hydrolase L-1), altered energy production (alpha-enolase), and diminished growth cone elongation and directionality (dihydropyrimindase-related protein 2). Taken together, these studies outlined above suggest that Met-35 is key to the oxidative stress and neurotoxic properties of Abeta(1-42) and may help explain the apoE allele dependence on risk for AD, some of the functional and structural alterations in AD brain, and strongly support a causative role of Abeta(1-42)-induced oxidative stress and neurodegeneration in AD.
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PMID:Amyloid beta-peptide (1-42)-induced oxidative stress and neurotoxicity: implications for neurodegeneration in Alzheimer's disease brain. A review. 1260 22

The purpose of this study was to clarify the anti-fatigue effect of Conclevan, which is mainly composed of liver hydrolysate, via a forced swimming test using mice. Conclevan was administered to mice for 6 weeks, and a forced swimming test was conducted to measure swimming time. After six weeks, the blood ammonia and glutamine concentrations were measured. In the Conclevan administration group, swimming time increased significantly compared to the swimming control group. In the swimming control group, an increase in blood ammonia and a decrease in blood glutamine were observed, relative to the non-swimming control group. In the Conclevan administration group, the increased blood ammonia and decreased blood glutamine induced by swimming were significantly reduced, compared to the swimming control group. The mRNA expression levels of the hepatic enzymes of the urea cycle (carbamoyl-phosphate synthetase, argininosuccinate synthetase, and arginase) and glutamine synthesis (glutamate dehydrogenase and glutamine synthetase) were significantly increased in the Conclevan administration group, compared to the swimming control group. The results of this study demonstrated the anti-fatigue effects of Conclevan. This product may inhibit an increase in the fatigue-inducing ammonia concentration in the blood by increasing the expression of hepatic enzymes, which convert ammonia to urea, leading to increased swimming time. In addition, Conclevan may prolong swimming time by increasing the hepatic synthesis of glutamine, which is an important amino acid for supplying energy in muscles.
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PMID:Effect of Conclevan on endurance capacity in mice. 2229 54