Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.99.3 (heme oxygenase)
 4,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Carbon monoxide (CO) is a signaling gas produced intracellularly by heme oxygenase (HO) enzymes using heme as a substrate. During heme breakdown, HO-1 and HO-2 release CO, biliverdin, and Fe(2+). In this study, we investigated the effects of manipulation of the HO-1 system in an in vivo model of focal ischemia-reperfusion (FIR) in the rat heart. Male Wistar albino rats, under general anesthesia and artificial ventilation, underwent thoracotomy, the pericardium was opened, and a silk suture was placed around the left descending coronary artery; ischemia was induced by tightening the suture and was monitored for 30 min. Subsequently, the ligature was released to allow reperfusion lasting for 60 min. The first group of rats was sham operated and injected intraperitoneally (i.p.) with saline. The second group underwent FIR. The third group was treated ip 18 hr before FIR with hemin (4 mg/kg). The fourth group was pretreated ip 24 hr before FIR and 6 hr before hemin with zinc protoporphyrin IX (ZnPP-IX, 50 microg/kg). Specimens of the left ventricle were taken for determination of HO expression and activity, infarct size, malonyldialdehyde (MDA) production, and tissue calcium content. FIR led to a significant increase in the generation of MDA and notably raised tissue calcium levels. Induction of HO-1 by hemin significantly decreased infarct size, incidence of reperfusion arrhythmias, MDA generation, and calcium overload induced by FIR. These effects were prevented by the HO-1 inhibitor ZnPP-IX. The present experiments show that the concerted actions of CO, iron, and biliverdin/bilirubin modulate the FIR-induced myocardial injury.
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PMID:Heme oxygenase-1 and the ischemia-reperfusion injury in the rat heart. 1270 84

Ischemia/reperfusion (I/R) injury is a multifactorial process that affects graft function after liver transplantation. An understanding of the mechanisms involved in I/R injury is essential for the design of therapeutic strategies to improve the outcome of liver transplantation. The generation of reactive oxygen species subsequent to reoxygenation inflicts tissue damage and initiates a cascade of deleterious cellular responses leading to inflammation, cell death, and ultimate organ failure. Increased experimental evidence has suggested that Kupffer cells and T cells mediate the activation of neutrophil inflammatory responses. Activated neutrophils infiltrate the injured liver in parallel with increased expression of adhesion molecules on endothelial cells. The heme oxygenase system is among the most critical of the cytoprotective mechanisms activated during cellular stress, exerting antioxidant and anti-inflammatory functions, modulating the cell cycle, and maintaining the microcirculation. Finally, the activation of toll-like receptors on Kupffer cells may play a fundamental role in exploring new therapeutic strategies based on the concept that hepatic I/R injury represents a case for a host "innate" immunity.
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PMID:Hepatic ischemia/reperfusion injury--a fresh look. 1271 Sep 39

Polyphenolic compounds, such as resveratrol, are naturally present at high concentration in grape skin, seeds, and red wine. Resveratrol is present in cis and trans isoforms and the major trans isomer is the biologically active one. Epidemiologic studies have revealed a reduced incidence of cardiovascular risk associated with consumers of red wine; this has been popularized as the French paradox. Resveratrol has been shown to have significant antioxidant properties in a variety of in vitro and in vivo models. It can reduce ischemic damage in heart ischemia reperfusion injury and also in brain ischemia/reperfusion in rodent models. Due to the high rate of oxygen consumption in the brain, and especially low levels of antioxidant defense enzymes, this organ is particularly susceptible of free radical damage. Most of the protective biological actions associated with resveratrol have been associated with its intrinsic radical scavenger properties. We have investigated the possibility of other indirect pathways by which resveratrol can exert its neuroprotective abilities. We have specifically tested whether heme oxygenase neuroprotective enzyme could be stimulated after resveratrol treatment. Using primary neuronal cultures, resveratrol was able to significantly induce heme oxygenase 1, whereas vehicle control showed no effect. No detectable toxicity was quantified. It is well established that after stroke significant levels of intracellular heme levels increase. The source of free heme comes mainly from several heme-containing enzymes. Heme (iron-protoporphyrin IX) is a pro-oxidant and its rapid degradation by heme oxygenase is believed to be protective. Moreover, the generation of heme metabolites can also have their own intrinsic cellular properties. All together, increased heme oxygenase activity by resveratrol is a unique pathway by which this compound can exert its neuroprotective actions.
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PMID:Potential mechanism by which resveratrol, a red wine constituent, protects neurons. 1285 18

This article summarizes strategies to protect the liver from injuries caused by ischemia and reperfusion. Three different sections (i.e., surgical and pharmacologic strategies and gene therapy) present approaches to enhance the survival and viability of the liver in various surgical procedures including liver transplantation. The first section reviews approaches using surgical interventions such as ischemic preconditioning and intermittent clamping. Their protective effects are discussed with respect to the mechanism of injury. In the second section, pharmacologic agents targeting microcirculation, oxidative stress, proteases, and inflammation are described. Mechanisms of injury and their suppression by a wide variety of drugs are discussed. The third section focuses on gene therapy. Potential target genes have been identified (e.g., superoxide dismutase or heme oxygenase). Animal experiments in which the liver injury is reduced successfully may pave the way to novel strategies applied to different liver diseases in humans.
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PMID:Protective strategies against ischemic injury of the liver. 1294 36

Ischemia/reperfusion is the main cause of hepatic damage consequent to temporary clamping of the hepatoduodenal ligament during liver surgery as well as graft failure after liver transplantation. In recent years, a number of animal studies have shown that pre-exposure of the liver to transient ischemia, hyperthermia, or mild oxidative stress increases the tolerance to reperfusion injury, a phenomenon known as hepatic preconditioning. The development of hepatic preconditioning can be differentiated into 2 phases. An immediate phase (early preconditioning) occurs within minutes and involves the direct modulation of energy supplies, pH regulation, Na(+) and Ca(2+) homeostasis, and caspase activation. The subsequent phase (late preconditioning) begins 12-24 hours after the stimulus and requires the synthesis of multiple stress-response proteins, including heat shock proteins HSP70, HSP27, and HSP32/heme oxygenase 1. Hepatic preconditioning is not limited to parenchymal cells but ameliorates sinusoidal perfusion, prevents postischemic neutrophil infiltration, and decreases the production of proinflammatory cytokines by Kupffer cells. This latter effect is important in improving systemic disorders associated with hepatic ischemia/reperfusion. The signals triggering hepatic preconditioning have been partially characterized, showing that adenosine, nitric oxide, and reactive oxygen species can activate multiple protein kinase cascades involving, among others, protein kinase C and p38 mitogen-activated protein kinase. These observations, along with preliminary studies in humans, give a rationale to perform clinical trials aimed at verifying the possible application of hepatic preconditioning in preventing ischemia/reperfusion injury during liver surgery.
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PMID:Recent insights on the mechanisms of liver preconditioning. 1459 65

Gene therapy is the use of gene delivery as a means to achieve high levels of the therapeutic gene product (ie, "drug" delivery) to treat acquired cardiovascular diseases. Human gene therapy for cardiovascular disease is expected to provide important advances in therapeutic angiogenesis, myocardial protection, myocardial regeneration and repair, restenosis, prevention of bypass graft failure, and risk-factor management. The data from ongoing phase 2 and future phase 3 studies will provide evidence to show whether therapeutic angiogenesis is effective, and these studies will identify the types of patients who may benefit. An important therapeutic target is the cell cycle. Data from the Project in Ex-Vivo Vein Graft Engineering via Transfection (PREVENT) I and II studies suggest that a synthetic DNA decoy can sequester the E2F family of transcription factors and arrest cells at the gap period (G1) checkpoint. This mechanism prevents intimal hyperplasia, which is associated with atherosclerosis and coronary graft failure. Administration of a myocardial protective gene (eg, heme oxygenase) via a recombinant adeno-associated virus vector reduces infarct size in animal models of ischemia and reperfusion. Other studies have shown that fractionated bone marrow stem cells promote myocardial repair and regeneration in myocardial infarction. If applied in humans, it will be possible to use a single administration of gene therapy to provide long-term prophylaxis against secondary coronary events and to promote myocardial repair in patients who have experienced an infarct, as well as in those at high risk of myocardial injury. In the future, new technology using stable gene integration may lead to the development of more effective and lifelong therapy for diabetes, familial homozygous hypercholesterolemia, and other acquired diseases.
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PMID:Predicting the future of human gene therapy for cardiovascular diseases: what will the management of coronary artery disease be like in 2005 and 2010? 1461 24

The aim of the study was to determine the role of both an inducible isoform of heme oxygenase (HO-1) and products of heme catabolism (carbon monoxide (CO), cardiac bilirubin and Fe2+) in protecting myocardium against post-ischemic myocardial dysfunction. Rat hearts were isolated and perfused according to the Langendorff technique to evaluate the recovery of myocardial function after total ischemia (20 min) and reperfusion (40 min) and production of reactive oxygen forms at a reperfusion phase. Ischemia/reperfusion caused impairment in myocardial function: left ventricular developing pressure (LVDP) was shown to be decreased, while end-diastolic pressure (EDP) and both coronary perfusion pressure and coronary resistance increased. Free oxygen radicals were generated at the reperfusion phase which led to injuries to cardiomyocytes and creatine kinase efflux into perfusate. We have found that upregulation of HO-1 by preliminary (24 h before ischemia) injections of 25 mg/kg hemin (i.p.) resulted in improving the myocardial function due to increasing the enzyme activity and forming the cardial bilirubine, while generation of reactive oxygen forms was inhibited, as well as the contents of creatine kinase reduced. As a result, impairment in cardiomyocytes diminished, and coronary vessels dilated to improve the functional parametres of the heart work.
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PMID:[Cardioprotective effect of heme oxygenase-1 induction by hemin on the isolated rat heart during ischemia--reperfusion]. 1496 33

Carbon monoxide (CO), a product of organic oxidation processes, arises in vivo during cellular metabolism, most notably heme degradation. CO binds to the heme iron of most hemoproteins. Tissue hypoxia following hemoglobin saturation represents a principle cause of CO-induced mortality in higher organisms, though cellular targets cannot be excluded. Despite extreme toxicity at high concentrations, low concentrations of CO can confer cytoprotection during ischemia/reperfusion or inflammation-induced tissue injury. Likewise, heme oxygenase, an enzyme that produces CO, biliverdin and iron, as well as a secondary increase in ferritin synthesis, from the oxidation of heme, can confer protection in vivo and in vitro. CO has been shown to affect several intracellular signaling pathways, including guanylate cyclase, which generates guanosine 3':5' cyclic monophosphate and the mitogen-activated protein kinases (MAPK). Such pathways mediate, in part, the known vasoregulatory, anti-inflammatory, anti-apoptotic and anti-proliferative effects of this gas. Exogenous CO delivered at low concentrations is showing therapeutic potential as an anti-inflammatory agent and as such can modulate numerous pathophysiological states. This review will delve into the biological significance and medical applications of this gas molecule.
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PMID:Carbon monoxide in biology and medicine. 1498 28

The purpose of this study was to test specific mechanisms of protection afforded the rat extensor digitorum longus (EDL) muscle during ischemic tolerance. Two days following five cycles of 10 min ischemia and 10 min reperfusion, heme oxygenase (HO) and calcium-dependent nitric oxide synthase (cNOS) activities were increased 2- and 2.5-fold (p <.05), respectively. Interestingly, calcium-independent NOS (iNOS) activity was completely downregulated (p <.05). The levels of superoxide dismutase (SOD) and catalase were increased 2-fold (p <.05), while glutathione peroxidase activity remained unchanged from non-preconditioned controls. Using intravital microscopy combined with chromium mesoporphyrin (CrMP), a selective HO inhibitor, and l-NAME, a NOS inhibitor, the roles of HO and cNOS were evaluated. Ischemic tolerance in the EDL muscle, 48 h after the preconditioning stimulus, was characterized by complete protection from both microvascular perfusion deficits and tissue injury after a 2-h period of ischemia. Removal of NOS activity completely removed the benefit afforded microvascular perfusion, while inhibition of HO activity prevented the parenchymal protection. These data suggest that ischemic tolerance within skeletal muscle is associated with the upregulation of specific cytoprotective proteins and that the benefits afforded by cNOS and HO activity are spatially discrete to the microvasculature and parenchyma, respectively.
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PMID:Protective mechanisms during ischemic tolerance in skeletal muscle. 1503 56

Tissue attenuates to injury by the effects of heme oxygenase (HO)-1. The induction of HO-1 expression is modulated by a (GT)(n) dinucleotide polymorphism in the promoter of the gene, of which increased activity is associated with short (S) (<or=27) repeats. We investigated the influence of this HO-1 gene polymorphism on renal transplant survival. DNA from 387 recipients and 384 donors was genotyped and we divided the HO-1 alleles into two subclasses, the S (<or=27 repeats) class and long (L) class (>27 repeats). Graft survival was associated with donor and not with recipient HO-1 gene polymorphism (log rank p = 0.005; hazard ratio 0.51, 95% CI 0.32-0.83). The beneficial effect of the donor HO-1 genotype was observed in grafts exposed to prolonged cold ischemia time and acute rejection. Patients who received a kidney from L-homozygotes lost their graft significantly more often to chronic allograft nephropathy (CAN) than carriers of S-alleles (p = 0.015). Multivariate analysis showed reduced risk for graft failure in kidneys with S-alleles in comparison to L-homozygotes (odds ratio 0.50, 95% CI 0.27-0.93, p = 0.03). Kidneys that are carriers of HO-1 S-allele are less vulnerable to tissue injury resulting in less CAN and better graft survival.
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PMID:Fundamental role for HO-1 in the self-protection of renal allografts. 1841 43


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