Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypoxic-ischemic brain injury involves an increased formation of reactive oxygen species. Key factors in the cellular protection against such agents are the GSH-associated reactions. In the present study we examined alterations in total glutathione and GSSG concentrations in mitochondria-enriched fractions and tissue homogenates from the cerebral cortex of 7-day-old rats at 0, 1, 3, 8, 14, 24 and 72 h after hypoxia-ischemia. The concentration of total glutathione was transiently decreased immediately after hypoxia-ischemia in the mitochondrial fraction, but not in the tissue, recovered, and then decreased both in mitochondrial fraction and homogenate after 14 h, reaching a minimum at 24 h after hypoxia-ischemia. The level of GSSG was approximately 4% of total glutathione and increased selectively in the mitochondrial fraction immediately after hypoxia-ischemia. The decrease in glutathione may be important in the development of cell death via impaired free radical inactivation and/or redox related changes. The effects of hypoxia-ischemia on the concentrations of selected amino acids varied. The levels of phosphoethanolamine, an amine previously reported to be released in ischemia, mirrored the changes in glutathione. GABA concentrations initially increased (0-3 h) followed by a decrease at 72 h. Glutamine levels increased, whereas glutamate and aspartate were unchanged up to 24 h after the insult. The results on total glutathione and GSSG are discussed in relation to changes in mitochondrial respiration and microtubule associated protein-2 (MAP2) which are reported on in accompanying paper [64].
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PMID:Alterations in glutathione and amino acid concentrations after hypoxia-ischemia in the immature rat brain. 1115 60

Although it is considered that L-Glutamine (L-Gln) supplementation improves gut morphology and survival in animal models such as radiation and drug-induced enterocolitis, the mechanisms underlying are far from being established. Recently, Gln has been reported to give protection against stress in in vitro intestinal epithelial cell lines through the induction of heat shock proteins (HSPs). This study is designed to examine whether L-Gln may induce cytoprotective molecules such as heme oxygenase-1/HSP32 (HO-1) and reduced glutathione (GSH) in in vivo intestinal tissues, and to clarify whether these molecules may play a role in warm ischemia and reperfusion (I/R) injury. We measured the releases of serotonin and tumor necrosis factor-alpha (TNF-alpha), and graft survival as viability assays following reperfusion of warm ischemically injured intestinal grafts. The substantial expression of HO-1 after L-Gln administration was observed in villous epithelial cells, crypts and muscular layers, and peaked at 6 h, while that of the control group pretreated with lactated Ringer (LR) solution was observed throughout tissues to be slightly similar to those of fresh untreated tissues. Tissue GSH contents slightly increased 24 h after administration and were less reduced through the periods of I/R than those of the LR group. Releases of serotonin and TNF-alpha in L-Gln group were attenuated during the brief periods of warm ischemia, compared with those in the LR group. A significant graft survival rate was also observed between both groups (6/6 of L-Gln group vs. 1/6 of LR group; p < 0.05). In conclusion, the protective effects of L-Gln in small intestines against warm I/R injury were considered to be in part mediated by up-regulation of molecules such as HO-1 and GSH via cellular antioxidant activity. Thus, L-Gln pretreatment may represent an innovative approach to the prevention of complex I/R injury.
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PMID:[L-glutamine-induced heme oxygenase-1 protects small intestine from warm ischemia and reperfusion injury in the rat]. 1123 9

A rat four-vessel cerebral occlusion model was used to examine the effects of D-lactate and oxamate, a lactate dehydrogenase inhibitor, on cortical window superfusate levels of amino acids, glucose and L-lactate. Superfusate levels of aspartate, glutamate, taurine, GABA and phosphoethanolamine rose during ischemia and then declined during reperfusion. Glycine and alanine levels tended to increase during reperfusion, whereas glutamine levels were lower. Serine levels were not altered. Glucose levels declined rapidly during ischemia and recovered during reperfusion. Lactate levels were sustained during ischemia and increased during reperfusion. Unlike L-lactate, which attenuated ischemia/reperfusion (I/R) evoked amino acid release (J.W. Phillis, D. Song, L.L. Guyot, M.H. O'Regan, Lactate reduces amino acid release and fuels recovery of function in the ischemic brain, Neurosci. Lett. 272 (1999) 195-198), topical application of D-lactate (20 mM), which is not used as an energy substrate, enhanced the I/R release of aspartate, glutamate, GABA and taurine into cortical superfusates, and also elevated L-lactate levels above those in the controls. Glucose levels were not altered. Oxamate (20 mM) application elevated the pre-ischemia levels of alanine, glycine and GABA and those of GABA during ischemia. Levels of all amino acids, with the exception of phosphoethanolamine, were elevated during reperfusion. Oxamate, an inhibitor of lactate dehydrogenases 1 and 5, did not alter the pattern of efflux of glucose and L-lactate. In the presence of oxamate, L-lactate (20 mM) failed to inhibit amino acid release. The failure of D-lactate to attenuate amino acid release confirms the inability of this isomer to act as a metabolic substrate. The oxamate data indicate that inhibition of lactate dehydrogenase is detrimental to the viability of cortical cells during I/R, even though extracellular lactate levels are elevated. The pre-ischemia increases in alanine and glycine are suggestive of elevations in pyruvate as a result of the block of its conversion to lactate, with transamination reactions converting pyruvate to form these amino acids. In summary, the results further substantiate the concept of a role for L-lactate as a cerebral energy substrate.
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PMID:Further studies on the effects of topical lactate on amino acid efflux from the ischemic rat cortex. 1136 47

After exhaustive exercise, intravenous or oral glutamine promoted skeletal muscle glycogen storage. However, when glutamine was ingested with glucose polymer, whole-body carbohydrate storage was elevated, the most likely site being liver and not muscle, possibly due to increased glucosamine formation. The rate of tricarboxylic acid (TCA) cycle flux and hence oxidative metabolism may be limited by the availability of TCA intermediates. There is some evidence that intramuscular glutamate normally provides alpha-ketoglutarate to the mitochondrion. We hypothesized that glutamine might be a more efficient anaplerotic precursor than endogenous glutamate alone. Indeed, a greater expansion of the sum of muscle citrate, malate, fumarate and succinate concentrations was observed at the start of exercise (70% VO2(max)) after oral glutamine than when placebo or ornithine alpha-ketoglutarate was given. However, neither endurance time nor the extent of phosphocreatine depletion or lactate accumulation during the exercise was altered, suggesting either that TCA intermediates were not limiting for energy production or that the severity of exercise was insufficient for the limitation to be operational. We have also shown that in the perfused working rat heart, there is a substantial fall in intramuscular glutamine and alpha-ketoglutarate, especially after ischemia. Glutamine (but not glutamate, alpha-ketoglutarate or aspartate) was able to rescue the performance of the postischemic heart. This ability appears to be connected to the ability to sustain intracardiac ATP, phosphocreatine and glutathione.
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PMID:Interaction between glutamine availability and metabolism of glycogen, tricarboxylic acid cycle intermediates and glutathione. 1153 98

Sequestration of parasitized erythrocytes in the central nervous system microcirculation and increased cerebrospinal fluid lactate are prominent features of cerebral malaria (CM), suggesting that sequestration causes mechanical obstruction and ischemia. To examine the potential role of ischemia in the pathogenesis of CM, Plasmodium berghei ANKA (PbA) infection in CBA mice was compared to infection with P. berghei K173 (PbK) which does not cause CM (the non-CM model, NCM). Cerebral metabolite pools were measured by (1)H nuclear magnetic resonance spectroscopy during PbA and PbK infections. Lactate and alanine concentrations increased significantly at the terminal stage of CM, but not in NCM mice at any stage. These changes did not correlate with parasitemia. Brain NAD/NADH ratio was unchanged in CM and NCM mice at any time studied, but the total NAD pool size decreased significantly in the CM mice on day 7 after inoculation. Brain levels of glutamine and several essential amino acids were increased significantly in CM mice. There was a significant linear correlation between the time elapsed after infection and small, progressive decreases in the cell density/cell viability markers glycerophosphocholine and N-acetylaspartate in CM, indicative of gradual loss of cell viability. The metabolite changes followed a different pattern, with a sudden significant alteration in the levels of lactate, alanine, and glutamine at the time of terminal CM. In NCM, there were significant decreases with time of glutamate, the osmolyte myo-inositol, and glycerophosphocholine. These results are consistent with an ischemic change in the metabolic pattern of the brain in CM mice, whereas in NCM mice the changes were more consistent with hypoxia without vascular obstruction. Mild obstructive ischemia is a likely cause of the metabolic changes during CM, but a role for immune cell effector molecules cannot be ruled out.
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PMID:Is ischemia involved in the pathogenesis of murine cerebral malaria? 1154 3

The discovery of the resistance to activated protein C (APCR) has provoked a new insight into the etiopathogenesis of venous and arterial thrombosis. APCR is determined in 95% genetically by point mutation in the gene for factor V resulting in substitution of arginine in the position 506 by glutamine. This change makes the activated form of factor V (factor Va) resistant to the cleavage by protein C in the place, where the cleavage takes place most quickly under normal conditions. The mutant factor V is known as factor V Leiden. Factor V Leiden preserves its procoagulation activity for a longer period, resulting thus into thrombophilia with all its negative consequences. The inherited deficiencies of antithrombin III, protein C and protein S occur in 10% of patients suffering from venous thrombosis, whereas factor V Leiden is present in as many as 20 to 60%. Thus, it seems that factor V Leiden is the most important inherited risk factor of venous thrombosis. The results of several trials did not indicate the participation of APCR in the development of myocardial infarction. On the other hand, APCR seems to be a risk factor of cerebrovascular accidents, especially of stroke and transitory brain ischemia. Factor V Leiden is an important risk factor of abortions, especially those occurring in the second trimester of pregnancy. According to recent results, factor V Leiden is considered to play a role in the pathogenesis of venous and arterial thromboses in children. The significant risk potential of factor V Leiden with respect to venous thrombosis development and relatively simple diagnosis of this mutation predispose the investigation of this disorder to become the screening method in indicated groups of patients. The investigation of APCR is recommended in all patients with either first or reoccurring attacks of venous thrombosis or thromboembolism, in patients with positive family history of thrombosis and thromboembolism and in women with repeated abortions, particularly in the second trimester of pregnancy. The investigation of APCR in selected groups of patients and early prophylactic anticoagulation therapy may be important in thrombosis prevention in situations with an increased thrombotic potential. (Tab. 1, Ref. 78.)
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PMID:Resistance to activated protein C--frequent etiologic factor for venous thrombosis. 1172 76

Astrocytes are intimately involved in both glutamate and gamma-aminobutyric acid (GABA) synthesis, and ischemia-induced disruption of normal neuroastrocytic interactions may have important implications for neuronal survival. The effects of middle cerebral artery occlusion (MCAO) on neuronal and astrocytic intermediary metabolism were studied in rats 30, 60, 120, and 240 minutes after MCAO using in vivo injection of [1-13C]glucose and [1,2- 13C]acetate combined with ex vivo 13C magnetic resonance spectroscopy and high-performance liquid chromatography analysis of the ischemic core (lateral caudoputamen and lower parietal cortex) and penumbra (upper frontoparietal cortex). In the ischemic core, both neuronal and astrocytic metabolism were impaired from 30 minutes MCAO. There was a continuous loss of glutamate from glutamatergic neurons that was not replaced as neuronal glucose metabolism and use of astrocytic precursors gradually declined. In GABAergic neurons astrocytic precursors were not used in GABA synthesis at any time after MCAO, and neuronal glucose metabolism and GABA-shunt activity declined with time. No flux through the tricarboxylic acid cycle was found in GABAergic neurons at 240 minutes MCAO, indicating neuronal death. In the penumbra, the neurotransmitter pool of glutamate coming from astrocytic glutamine was preserved while neuronal metabolism progressively declined, implying that glutamine contributed significantly to glutamate excitotoxicity. In GABAergic neurons, astrocytic precursors were used to a limited extent during the initial 120 minutes, and tricarboxylic acid cycle activity was continued for 240 minutes. The present study showed the paradoxical role that astrocytes play in neuronal survival in ischemia, and changes in the use of astrocytic precursors appeared to contribute significantly to neuronal death, albeit through different mechanisms in glutamatergic and GABAergic neurons.
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PMID:Differences in neurotransmitter synthesis and intermediary metabolism between glutamatergic and GABAergic neurons during 4 hours of middle cerebral artery occlusion in the rat: the role of astrocytes in neuronal survival. 1174 Feb 7

In the past year there have been many advances in the area of small bowel physiology and pathology and therapy. In preparation for this review, over 1500 papers were assessed. The focus is on presenting clinically useful information for the practicing gastroenterologist. Selected important clinical learning points include the following: (1) glutamine may restore the AIDs-associated increased intestinal permeability to normal; (2) substance P is a major mediator of diarrhea caused by Costridium difficile toxin A, acting by binding to a G-protein-coupled receptor, and represents a possible 2therapeutic target; (3) the serological diagnosis of celiac disease has been greatly enhanced with the use of anti-endomysial antibody testing, and the recent antitransglutaminase; (4) a quarter of patients with celiac disease may have secondary pancreatic insufficiency and require enzyme replacement therapy; (5) in the patient with unexplained elevation in the serum transaminase concentration, consider celiac disease as an obscure possibility; (6) bosentan and endothelin receptor agonist may prove to be useful in reducing gut ischemia in patients with septic shock; and (7) the administration of recombinant human fibroblast growth factor-2 may prove to be useful to prevent radiation damage to the gastrointestinal tract.
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PMID:Small bowel review: diseases of the small intestine. 1176 46

The most basic mechanism of cellular protection involves the expression of a highly conserved family of essential proteins, known as heat shock or stress proteins (HSPs). The expression of these proteins after a sublethal insult can induce "stress tolerance" and protect against a subsequent stress that otherwise would be lethal. Experimental data have shown that preinduction of the heat stress response can provide marked protection against many forms of cellular injury, including ischemia and reperfusion, lung injury, and shock. However, induction of HSPs to improve outcome in human disease has not been exploited because laboratory induction agents are themselves toxic and not clinically relevant. Many researchers have found that glutamine (GLN), a conditionally essential amino acid, can enhance stress-induced HSP expression in vitro and improve cell survival against a variety of stressful stimuli. Further, recent data from me and my colleagues indicate that a single dose of intravenous GLN can enhance HSP expression, decrease end-organ injury, and enhance survival from septic shock in the intact rat. Thus GLN, which is beneficial in many settings of critical illness and injury, may be a clinically applicable enhancer of HSP expression. These results indicate that GLN could be used to enhance HSP expression and attenuate end-organ injury in situations when a major clinical stress is anticipated, such as before major surgical procedures (e.g., cardiac, vascular, and transplantation) or in the critically ill.
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PMID:Glutamine and heat shock protein expression. 1188 94

L-Glutamine (Gln) is known to have protective effect on the small intestine under deleterious stressful condition. Although the mechanism by which Gln confers intestinal cellular protection remains unclear, its potential role may be mediated via signal transduction including stress response genes and anti-apoptotic genes. Herein, we examined a possible role of stress response genes in warm ischemically injured small intestines. We measured mRNA and protein expression of heme oxygenase (HO)-1, Bcl-2 and Bax at different time points after Gln administration. Warm ischemia model was made by clamping of the superior mesenteric artery for 60 min. After reperfusion, tissue samples were taken for end labeling of nuclear DNA fragments (TdT-mediated d-uridine triphosphate biotin nick end labeling; TUNEL) and hematoxylin-eosin staining. In Gln-treated group, the substantial expression of HO-1 mRNA peaked at 3 h and reduced thereafter, while HO-1 protein synthesis was noted within 3 h and reached plateau thereafter. NO-1-positive components were markedly detected in the villus epithelial cells and crypts. The ratios of Bcl-2/Bax mRNA expression after Gln administration peaked at 3 h and reduced thereafter until 24 h. Bcl-2 immunoreactive protein was enhanced in Gln group, whereas Bax was faintly detected. Following reperfusion, less TUNEL-positive staining of the top of the villi and more prompt recovery of denuded villus epithelial cells were noted in Gln group, compared with those in untreated and lactated Ringer-treated control groups. In conclusion, a concomitant expression of anti-oxidative HO-1 and anti-apoptotic Bcl-2 molecules induced by non-toxic amino acid, Gln, may alleviate or even prevent intestinal warm ischemia and reperfusion injury, attenuating programmed cell death and promoting its reepithelialization.
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PMID:[Impact of stress response genes induced by L-glutamine on warm ischemia and reperfusion injury in the rat small intestine]. 1196 53


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