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

Erythropoietin (EPO) promotes neuronal survival after cerebral ischemia in vivo and after hypoxia in vitro. However, the mechanisms underlying the protective effects of EPO on ischemic/hypoxic neurons are not fully understood. The present in vitro experiments showed that EPO attenuated neuronal damage caused by chemical hypoxia at lower extracellular concentrations (10(- 4)-10(-2) U/ml) than were previously considered. Moreover, EPO at a concentration of 10(-3) U/ml up-regulated Bcl-xL mRNA and protein expressions in cultured neurons. Subsequent in vivo study focused on whether EPO rescued hippocampal CA1 neurons from lethal ischemic damage and up-regulated the expressions of Bcl-xL mRNA and protein in the hippocampal CA1 field of ischemic gerbils. EPO was infused into the cerebroventricles of gerbils immediately after 3 min of ischemia for 28 days. Infusion of EPO at a dose of 5 U/day prevented the occurrence of ischemia-induced learning disability. Subsequent light microscopic examinations showed that pyramidal neurons in the hippocampal CA1 field were significantly more numerous in ischemic gerbils infused with EPO (5 U/day) than in those receiving vehicle infusion. The same dose of EPO infusion caused significantly more intense expressions of Bcl-xL mRNA and protein in the hippocampal CA1 field of ischemic gerbils than did vehicle infusion. These findings suggest that EPO prevents delayed neuronal death in the hippocampal CA1 field, possibly through up-regulation of Bcl-xL, which is known to facilitate neuron survival.
 ...
PMID:Erythropoietin protects neurons against chemical hypoxia and cerebral ischemic injury by up-regulating Bcl-xL expression. 1189 94

Erythropoietin (EPO) is commonly used to treat anemias secondary to renal failure, malignancy, and AIDS. Although therapeutic complications are well described, overdose is rare. A 42-y-o man with AIDS confused his instructions for self-administration of interferon and EPO and began injecting himself daily with 10,000 units of EPO for several weeks. He presented with confusion, pain in his abdomen and feet, and a hemoglobin of 23.2 g/dLwith a hematocrit of 77.1%. The patient was treated with iv fluids, phlebotomy and 2 sessions of erythropheresis which removed 898 mL and 640 mL of red blood cells, respectively; his hemoglobin remained between 12-14 g/dL and symptoms resolved. His only sequelae involved skin loss over his toes, which did not require grafting. This rare case of EPO overdose highlights the complications of essential erythrocytosis, with central nervous system, peripheral, and presumed mesenteric ischemia.
 ...
PMID:Erythropoietin overdose treated with emergent erythropheresis. 1204 68

Erythropoietin (EPO) plays an important role in the brain's response to neuronal injury. Systemic administration of recombinant human EPO (rhEPO) protects neurons from injury after middle cerebral artery occlusion, traumatic brain injury, neuroinflammation, and excitotoxicity. Protection is in part mediated by antiapoptotic mechanisms. We conducted parallel studies of rhEPO in a model of transient global retinal ischemia induced by raising intraocular pressure, which is a clinically relevant model for retinal diseases. We observed abundant expression of EPO receptor (EPO-R) throughout the ischemic retina. Neutralization of endogenous EPO with soluble EPO-R exacerbated ischemic injury, which supports a crucial role for an endogenous EPO/EPO-R system in the survival and recovery of neurons after an ischemic insult. Systemic administration of rhEPO before or immediately after retinal ischemia not only reduced histopathological damage but also promoted functional recovery as assessed by electroretinography. Exogenous EPO also significantly diminished terminal deoxynucleotidyltransferase-mediated dUTP end labeling labeling of neurons in the ischemic retina, implying an antiapoptotic mechanism of action. These results further establish EPO as a neuroprotective agent in acute neuronal ischemic injury.
 ...
PMID:Erythropoietin administration protects retinal neurons from acute ischemia-reperfusion injury. 1213 Jun 65

Erythropoietin (EPO) prevents neuronal damage following ischemic, metabolic, and excitotoxic stress. In this study evoked extracellular field potentials (FP) were used to investigate the effect of EPO on synaptic transmission in hippocampal slice cultures. EPO treated cultured slices (40 units/ml for 48 h) showed significantly increased FP during and following oxygen and glucose deprivation compared with untreated control slices. The addition of the Jak2 inhibitor AG490 (50 microM for 48 h) blocked the EPO effect. These data suggest that EPO improves synaptic transmission during and following ischemia in hippocampal slice cultures.
 ...
PMID:Erythropoietin improves synaptic transmission during and following ischemia in rat hippocampal slice cultures. 1247 Aug 66

Erythropoietin (EPO) is an endogenous cytokine with antiapoptotic, antiinflammatory, and neurotrophic properties. Apart from being produced by the kidney, liver, and spleen in response to hypoxia, EPO is highly expressed in the brain during development and after neuropathological insults. The observation that receptors for EPO are present on brain capillaries and glial capillary end-feet has suggested that circulating (plasma) EPO may be transferred into the brain. This review summarizes the increasing number of studies indicating that peripherally administered recombinant human (rHu) EPO crosses the blood-brain barrier. Moreover, several of these studies have shown that peripherally administered rHuEPO can protect against the damage caused by a diversity of neuropathological conditions such as (a) stroke, (b) head and spinal cord trauma, (c) inflammatory and demyelinating conditions, (d) toxin-induced epileptic seizures, and (e) retinal ischemia. While all these studies are based on experiments in animal models, the effectiveness of rHuEPO in ischemic stroke in human patients has recently been suggested in a proof-of-concept trial, which is also discussed.
 ...
PMID:Recombinant human erythropoietin for neuroprotection: what is the evidence? 1253 71

Erythropoietin (Epo) prevents ischemia and hypoxia-induced neuronal death in vitro. Recent studies have shown that this cytokine also has in vivo neuroprotective effects in cerebral and spinal ischemia in adult rodents. In this study, we aimed to investigate the effect of systemically administered recombinant human Epo on infarct volume and apoptotic neuronal death in a newborn rat hypoxic-ischemic brain injury model. Our results showed that a single dose of intraperitoneal Epo treatment (1,000 U/kg) significantly decreased the mean infarct volume as compared to the control group. In contrast to the Epo-treated group, histopathological examination by positive terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling of the affected brain in control animals revealed widespread neuronal injury associated with numerous apoptotic cells. Morphometric analysis to determine the extent of damage quantitatively ascertained that the mean infarct volume was significantly lower in the Epo-treated group (p < 0.003). These results suggest the beneficial neuroprotective effect of Epo in this model of neonatal hypoxic-ischemic brain injury. To our knowledge, this is the first study that demonstrates a protective effect of Epo against hypoxia-ischemia in the developing brain.
 ...
PMID:Neuroprotective effect of erythropoietin on hypoxic-ischemic brain injury in neonatal rats. 1266 Apr 42

Erythropoietin (EPO), originally identified for its critical hormonal role in promoting erythrocyte survival and differentiation, is a member of the large and diverse cytokine superfamily. Recent studies have identified multiple paracrineautocrine functions of EPO that coordinate local responses to injury by maintaining vascular autoregulation and attenuating both primary (apoptotic) and secondary (inflammatory) causes of cell death. Experimental evidence also supports a role for EPO in repair and regeneration after brain and spinal cord injury, including the recruitment of stem cells into the region of damage. Tissue expression of the EPO receptor is widespread, especially during development, and includes the heart. However, it is currently unknown as to whether EPO plays a physiological function in adult myocardial tissue. We have assessed the potential protective role of EPO in vitro with adult rat cardiomyocytes, and in vivo in a rat model of myocardial infarction with reperfusion. The results show that EPO markedly prevents the apoptosis of cultured adult rat myocardiocytes subjected to 28 h of hypoxia (approximately 3% normal oxygen). Additional studies employing a rat model of coronary ischemia-reperfusion showed that the administration of recombinant human EPO (5,000 units/kg of body weight; i.p. daily for 7 days) reduces cardiomyocyte loss by approximately 50%, an extent sufficient to normalize hemodynamic function within 1 week after reperfusion. These observations not only suggest a potential therapeutic role for recombinant human EPO in the treatment of myocardial ischemia and infarction by preventing apoptosis and attenuating postinfarct deterioration in hemodynamic function, but also predict that EPO is likely a tissue-protective cytokine in other organs as well.
 ...
PMID:Recombinant human erythropoietin protects the myocardium from ischemia-reperfusion injury and promotes beneficial remodeling. 1266 57

Erythropoietin (Epo) exerts neuroprotection against neuronal death induced by ischemia and hypoxia in vitro and in vivo. Recent studies suggest that the neuroprotective effects of Epo may depend upon different mechanisms, including the inhibition of nitric oxide (NO). We recently demonstrated that Epo exerts neuroprotection in a model of neonatal hypoxic-ischemic brain damage. In the present study, we directly determined whether systemic administration of recombinant Epo modulates cerebral NO production in a neonatal rat model of hypoxic-ischemic brain injury. Seven-day-old Wistar rat pups were subjected to left carotid artery occlusion followed by 2.5 h of hypoxic exposure. Brain nitrite levels were evaluated in both hemispheres (carotid ligated or nonligated) by Griess reagent 72 h after the hypoxic-ischemic insult. Our results show that hypoxic-ischemic insult results a significant increase in NO production as compared with NO levels in hypoxic hemispheres and control animals. A single dose of Epo treatment (1,000 U/kg i.p.) significantly decreased NO overproduction in the hypoxic-ischemic hemisphere, whereas no significant change appeared in hypoxia alone or in controls. These data suggest that the selective inhibitory effect of Epo on NO overproduction could have a neuroprotective effect in neonatal hypoxic-ischemic brain injury.
 ...
PMID:Selective inhibition of nitric oxide in hypoxic-ischemic brain model in newborn rats: is it an explanation for the protective role of erythropoietin? 1463 Nov 67

Erythropoietin (Epo) has been shown to act as a neurotrophic and neuroprotective factor via binding to its receptor (EpoR) which is activated in adult brains following hypoxia and ischemia. However, no evidence suggests that cerebral ischemia can activate EpoR in the neonatal brain. In the present study, the changes in EpoR expression were investigated using a modified model of permanent focal cerebral ischemia (FCI) in 7-day-old rat pups. Western blot analysis with an anti-rabbit EpoR antibody revealed a significant increase in the EpoR protein in the ischemic areas, starting from 6 to 12 h after FCI. Moreover, many EpoR-positive cells were detected in the ischemic areas from 12 h after FCI, and the positive cells were identified as neurons and microglia/macrophage but not astrocytes 24 h after FCI. Additionally, double staining with a red in situ apoptosis detection kit and the EpoR antibody indicated that EpoR-positive cells were in apoptotic cell death in the ischemic area. Therefore, these results suggest that EpoR is activated in the ischemic areas of neonatal rats and plays an important role in brain injury during development.
 ...
PMID:Permanent focal cerebral ischemia activates erythropoietin receptor in the neonatal rat brain. 1473 57

Erythropoietin, a hemotopoietic growth factor, has brain protective actions. This study investigated the mechanisms of Recombinant Human EPO (rhEPO)-induced brain protection in neonates. An established rat hypoxia-ischemia model was used by ligation of the right common carotid artery of 7-day-old pups, followed by 90 minute of hypoxia (8% 02 and 92% N2) at 37 degrees C. Animals were divided into three groups: control, hypoxia-ischemia, and hypoxia-ischemia plus rhEPO treatment. In rhEPO treated pups, 300 units rhEPO was administered intraperitoneally 24 hours before hypoxia. rhEPO treatment (300 units) was administered daily for an additional 2 days. ELISA and immunohistochemistry examined the expression of EPO and EPOR. Brain weight, morphology, TUNEL assay, and DNA laddering evaluated brain protection. rhEPO abolished mortality (from 19% to 0%) during hypoxia insult, increased brain weight from 52% to 88%, reduced DNA fragmentation, and decreased TUNEL-positive cells. Real-time RT-PCR, Western blot, and immunohistochemistry revealed an enhanced expression of heat shock protein 27 (HSP27) in ischemic brain hemisphere. Double labeling of TUNEL with HSP27 showed most HSP27 positive cells were negative to TUNEL staining. rhEPO reduces brain injury, especially apoptotic cell death after neonatal hypoxia-ischemia, partially mediated by the activation of HSP27.
 ...
PMID:Mechanisms of erythropoietin-induced brain protection in neonatal hypoxia-ischemia rat model. 1474 52


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>