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)

"Trench foot" is a particular risk for those involved in adventure tourism, for soldiers in winter mountain training exercises, and for the homeless. Nonfreezing cold nerve injury is characterized by axonal degeneration, which is attributed to free radicals released during cycles of ischemia and reperfusion. This pilot study sought to determine whether the administration of antioxidants might prevent or ameliorate the development of cold nerve injury. Twenty-six rats were divided into two groups. Group 1 animals received, by gavage, a mixture of vitamin C (150 mg/kg/d), vitamin E (100 mg/kg/d), and N-acetyl-L-cysteine (250 mg/kg/d) daily for 4 weeks. Allopurinol (20 mg/kg/d) was added in the last 4 days of treatment. Group 2 animals served as controls and did not receive any antioxidant supplements. After 1 month, two cycles of sciatic nerve cooling (0 degrees C) were induced in 10 controls and 10 experimental animals using circulating water through a nerve cuff. Six additional control animals were subjected to surgery but did not undergo nerve cooling. All animals were killed on the third postoperative day, and their nerves were processed for ultrastructural and quantitative studies. The proportion of degenerated myelinated and unmyelinated axons showed no significant difference between treated and untreated animals. We conclude that the administration of commonly used antioxidants does not prevent cold nerve injury.
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PMID:Use of antioxidants for the prophylaxis of cold-induced peripheral nerve injury. 1236 67

The purpose of this study was to investigate whether combined inhibition of neuronal and inducible nitric oxide synthase (NOS) by 2-iminobiotin, free radical scavenging by allopurinol, and non-protein-bound iron chelation with deferoxamine improved cerebral oxygenation, electrocortical brain activity, and brain energy status during the first 24 h after hypoxia-ischemia (HI) in the newborn piglet. Forty-three newborn piglets were subjected to 1 h of severe HI by occluding both carotid arteries and phosphorous magnetic resonance spectroscopy ((31)P-MRS)-guided hypoxia, whereas five served as sham-operated controls. Upon reperfusion, piglets received vehicle (n=12), 2-iminobiotin (n=11), allopurinol (n=10), or deferoxamine (n=10). Cerebral oxygenation was recorded with near-infrared spectrophotometry (NIRS), electrocortical brain activity was assessed with amplitude-integrated EEG (aEEG), and cerebral energy status with (31)P-MRS. The oxygenated hemoglobin (HbO(2)) and total hemoglobin (tHb) were significantly increased in vehicle-treated piglets compared with 2-iminobiotin-treated and deferoxamine-treated piglets. No change in deoxygenated Hb (HHb) was demonstrated over time. The aEEG was significantly preserved in 2-iminobiotin- and deferoxamine-treated piglets compared with vehicle-treated piglets. Allopurinol treatment was not as effective as 2-iminobiotin treatment after HI. Phosphocreatine/inorganic phosphate ratios (PCr/P(i)) were significantly decreased for vehicle-treated piglets at 24 h post-HI, whereas 2-iminobiotin, allopurinol, and deferoxamine prevented the development of secondary energy failure. We speculate that the beneficial effects, especially of 2-iminobiotin, but also of deferoxamine, are due to reduced peroxynitrite-mediated oxidation.
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PMID:Pharmacological interventions in the newborn piglet in the first 24 h after hypoxia-ischemia. A hemodynamic and electrophysiological perspective. 1241 Mar 35

It has been reported that the xanthine oxidase inhibitor, allopurinol, has a protective effect on ischemia - reperfusion injury, but the precise mechanism of its action is still unclear. Therefore, in the present study the mechanisms of the myocardial protection of allopurinol were evaluated in isolated perfused rat hearts. Allopurinol significantly inhibited myocardial xanthine oxidase activity, and improved left ventricular dysfunction after ischemia - reperfusion. In addition, the lactate dehydrogenase content in the coronary effluent obtained after reperfusion was significantly decreased. ATP, ADP, AMP and IMP significantly decreased, whereas inosine, hypoxanthine and xanthine significantly increased after ischemia in both the control and allopurinol groups. The concentration of xanthine was significantly decreased after ischemia - reperfusion in the allopurinol group; however, allopurinol did not affect the other purine metabolites. To evaluate the accumulation of oxidative stress, thiobarbituric acid reactive substances (TBARS) production in myocardial tissue was measured and allopurinol significantly decreased TBARS formation after ischemia - reperfusion. Finally, myocardial hydroxyl radicals were directly measured by electron spin resonance spectroscopy with the nitroxide radical 4-hydroxy-2, 2,6,6-tetramethyl-piperidine-N-oxyl. Hydroxyl radicals significantly increased immediately after reperfusion, but were significantly decreased in the allopurinol group. In conclusion, allopurinol reduced myocardial injury after ischemia-reperfusion by suppressing oxidative stress, but not by salvage of ATP. These findings may lead to the development of new therapeutic strategies for myocardial ischemia - reperfusion injury.
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PMID:Allopurinol improves cardiac dysfunction after ischemia-reperfusion via reduction of oxidative stress in isolated perfused rat hearts. 1293 55

We analysed the effect of ischemia-reperfusion injury to renal parenchyma after unilateral renal artery clamping using urinary N-acetyl-beta-D-glucosaminidase (NAG) that is a sensitive parameter of early renal tubular injury. In the study 60 mongrel dogs were divided into 3 groups: in the 1st group the left renal artery was clamped for 45 minutes, in the 2nd group Allopurinol was administered before the clamping, the 3rd was the control group, where only laparotomy and closure of the abdomen was performed. Urinary NAG activity referring to urinary creatinine (NAG index) was determined before the operation, at the beginning of the reperfusion, in the 60th and 120th minute of the reperfusion then 1, 2, 3 and 5 days after the operation. The highest NAG indices relating to injury of the proximal tubuli were found at the beginning of the reperfusion, in the 60th and 120th minutes of the reperfusion, then NAG returned to preoperative level in each group. Significantly higher NAG indices were found in the ischemia-reperfusion group compared to the group with Allopurinol pretreatment. Renal ischemia-reperfusion injury and the protective effect of Allopurinol could be detected by lysosomal NAG enzyme. The injury of the tubular function was reversible so it could be a change in tubular function.
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PMID:[Determination of urinary NAG to detect renal ischemia-reperfusion injury and the protective effect of Allopurinol]. 1601 83

Postischemic myocardial contractile dysfunction is in part mediated by the burst of reactive oxygen species (ROS), which occurs with the reintroduction of oxygen. We hypothesized that tissue oxygen tension modulates this ROS burst at reperfusion. After 20 min of global ischemia, isolated rat hearts were reperfused with temperature-controlled (37.4 degrees C) Krebs-Henseleit buffer saturated with one of three different O2 concentrations (95, 20, or 2%) for the first 5 min of reperfusion and then changed to 95% O2. Additional hearts were loaded with 1) allopurinol (1 mM), a xanthine oxidase inhibitor, 2) diphenyleneiodonium (DPI; 1 microM), an NAD(P)H oxidase inhibitor, or 3) Tiron (10 mM), a superoxide scavenger, and were then reperfused with either 95 or 2% O2 for the first 5 min. ROS production and tissue oxygen tension were quantitated using electron paramagnetic resonance spectroscopy. Tissue oxygen tension was significantly higher in the 95% O2 group. However, the largest radical burst occurred in the 2% O2 reperfusion group (P < 0.001). Recovery of left ventricular (LV) contractile function and aconitase activity during reperfusion were inversely related to the burst of radical production and were significantly higher in hearts initially reperfused with 95% O2 (P < 0.001). Allopurinol, DPI, and Tiron reduced the burst of radical formation in the 2% O2 reperfusion groups (P < 0.05). Hypoxic reperfusion generates an increased ROS burst originating from multiple pathways. Recovery of LV function during reperfusion is inversely related to this oxygen radical burst, highlighting the importance of myocardial oxygen tension during initial reperfusion.
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PMID:Hypoxic reperfusion of the ischemic heart and oxygen radical generation. 1612 19

Adenosine, a purine nucleoside, is a potent inhibitory neuromodulator in the brain which may provide an important endogenous neuroprotective role during hypoxia-ischemia. Allopurinol, a xanthine oxidase inhibitor, blocks purine degradation and may result in the accumulation of purine metabolites, including adenosine, during hypoxia. The present study determines the effect of allopurinol administration prior to hypoxia on brain levels of adenosine and purine metabolites in the newborn piglet. Twenty-two newborn piglets (age 3-7 days) were studied: 5 untreated normoxic and 6 allopurinol-treated normoxic controls were compared to 5 untreated hypoxic and 6 allopurinol-treated hypoxic animals. Brain tissue energy metabolism was continuously monitored during hypoxia by (31)P NMR spectroscopy. Brain tissue levels of purines increased in both hypoxic groups during hypoxia, however, there were significantly higher increases in brain tissue levels of adenosine (66.5 +/- 30.5 vs. 19.4 +/- 10.7 nmol/gm), P < 0.01 and inosine (265 +/- 97.6 vs. 162.8 +/- 38.3 nmol/gm), P = 0.05 in the allopurinol-treated hypoxic group. Allopurinol inhibits purine degradation under severe hypoxic conditions and results in a significant increase in brain tissue levels of adenosine and inosine. The increased accumulation of CNS adenosine during hypoxia which is seen in the allopurinol-treated animals may potentiate adenosine's intrinsic neuroprotective mechanisms.
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PMID:Effect of allopurinol on brain adenosine levels during hypoxia in newborn piglets. 1644 3

Myocardial oxidative stress and Ca2+ overload induced by ischemia-reperfusion may be involved in the development and progression of myocardial dysfunction in heart failure. Xanthine oxidase, which is capable of producing reactive oxygen species, is considered as a culprit regarding ischemia-reperfusion injury of cardiomyocytes. Even though inhibition of xanthine oxidase by allopurinol in failing hearts improves cardiac performance, the regulatory mechanisms are not known in detail. We therefore hypothesized that allopurinol may prevent the xanthine oxidase-induced reactive oxygen species production and Ca2+ overload, leading to decreased calcium-responsive signaling in myocardial dysfunction. Allopurinol reversed the increased xanthine oxidase activity in ischemia-reperfusion injury of neonatal rat hearts. Hypoxia-reoxygenation injury, which simulates ischemia-reperfusion injury, of neonatal rat cardiomyocytes resulted in activation of xanthine oxidase relative to that of the control, indicating that intracellular xanthine oxidase exists in neonatal rat cardiomyocytes and that hypoxia-reoxygenation induces xanthine oxidase activity. Allopurinol (10 microM) treatment suppressed xanthine oxidase activity induced by hypoxia-reoxygenation injury and the production of reactive oxygen species. Allopurinol also decreased the concentration of intracellular Ca2+ increased by enhanced xanthine oxidase activity. Enhanced xanthine oxidase activity resulted in decreased expression of protein kinase C and sarcoendoplasmic reticulum calcium ATPase and increased the phosphorylation of extracellular signal-regulated protein kinase and p38 kinase. Xanthine oxidase activity was increased in both ischemia-reperfusion-injured rat hearts and hypoxia-reoxygenation-injured cardiomyocytes, leading to reactive oxygen species production and intracellular Ca2+ overload through mechanisms involving p38 kinase and extracellular signal-regulated protein kinase (ERK) via sarcoendoplasmic reticulum calcium ATPase (SERCA) and protein kinase C (PKC). Xanthine oxidase inhibition with allopurinol modulates reactive oxygen species production and intracellular Ca2+ overload in hypoxia-reoxygenation-injured neonatal rat cardiomyocytes.
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PMID:Allopurinol modulates reactive oxygen species generation and Ca2+ overload in ischemia-reperfused heart and hypoxia-reoxygenated cardiomyocytes. 1651 85

The hierarchy of endothelial progenitor cells (EPCs) in human umbilical cord blood has been disclosed. In this study we compare, for the first time, the angiogenic potential difference between two types of EPCs. We cultured mononuclear cells (MNCs) isolated from human umbilical cord blood using endothelial cell-conditioned medium and obtained two types of EPCs, referred to as circulating angiogenic cells (CACs) and high proliferative potential endothelial progenitor cells (HPP-EPCs). Both types of cells possess characteristics of EPCs, including expressing CD31, VE-cadherin, KDR and von Willebrand factor, uptake of Ac-LDL and binding to lectin. However, unlike CACs, which express CD14 but not CD133, HPP-EPCs express CD133 but not CD14. Also, unlike CACs, HPP-EPCs display stronger proliferation and clonogenic potential in vitro and show stronger ability to promote vascular growth in the hind-limb model of ischemia in mice (BALB/C-nu) in vivo.
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PMID:Angiogenic potential difference between two types of endothelial progenitor cells from human umbilical cord blood. 1702 Aug 9

Cumulative evidences have revealed that endothelial progenitor cell (EPC) transplantation can promote the neovascularization in ischemic tissue, but the mechanism of EPCs homing to the site of ischemia is poorly understood. In this study, to investigate the mechanism of human umbilical cord blood-derived high proliferative potential-endothelial progenitor cells (HPP-EPCs) homing to ischemic tissue we evaluated the expression of lymphocyte function-associated antigen-1 (LFA-1, or CD11a/CD18) and very late antigen-4 (VLA-4, or CD49d/CD29) in EPCs and the changes of expression level of their ligands, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), in ischemic tissue and performed the adhesion and migration assays to analyze the interaction between the receptors and ligands. Furthermore, we studied the roles of LFA-1 and VLA-4 in EPC homing in an ischemic model of mice. The results show that LFA-1 andVLA-4 were expressed in HPPEPCs and ICAM-1 and VCAM-1 were expressed in vessel endothelium in ischemic tissues. The pre-incubation of HPP-EPCs with neutralizing antibodies against CD11a or CD49d reduced adhesion and migration of HPP-EPCs in vitro and reduced recovery of hind-limb blood flow, capillary density and incorporation of HPP-EPC into ischemic tissues in vivo. Furthermore, the pre-incubation of HPP-EPCs with the combination of CD11a and CD49d antibodies led to synergistically negative effects on adhesion and transmigration of HPP-EPCs in vitro, and on the homing of HPP-EPCs to ischemic tissue and on neovascularization capacity in vivo. These results indicate that LFA-1 andVLA-4 are involved in HPP-EPC homing to ischemic tissues.
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PMID:LFA-1 and VLA-4 involved in human high proliferative potential-endothelial progenitor cells homing to ischemic tissue. 1713 77

It has now been firmly established that, not only ischemia/reperfusion, but also cold itself causes damage during kidney transplantation. Iron chelators or anti-oxidants applied during the cold plus rewarming phase are able to prevent this damage. At present, it is unknown if these measures act only during the cold, or whether application during the rewarming phase also prevents damage. We aimed to study this after cold normoxic and hypoxic conditions. LLC-PK1 cells were incubated at 4 degrees C in Krebs-Henseleit buffer for 6 or 24h, followed by 18 or 6h rewarming, respectively. Cold preservation was performed under both normoxic (95% air/5% CO2) and hypoxic (95% N2/5% CO2) conditions. The iron chelator 2,2'-DPD (100 microM), anti-oxidants BHT (20 microM) or sibilinin (200 microM), and xanthine oxidase inhibitor allopurinol (100 microM) were added during either cold preservation plus rewarming, or rewarming alone. Cell damage was assessed by LDH release (n=3-9). Addition of 2,2'-DPD and BHT during cold hypoxia plus rewarming did, but during rewarming alone did not prevent cell damage. When added during rewarming after 6h cold normoxic incubation, BHT and 2,2'-DPD inhibited rewarming injury compared to control (p<0.05). Allopurinol did not prevent cell damage in any experimental set-up. Our data show that application of iron chelators or anti-oxidants during the rewarming phase protects cells after normoxic but not hypoxic incubation. Allopurinol had no effect. Since kidneys are hypoxic during transplantation, measures aimed at preventing cold-induced and rewarming injury should be taken during the cold.
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PMID:Iron chelation or anti-oxidants prevent renal cell damage in the rewarming phase after normoxic, but not hypoxic cold incubation. 1739 62


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