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)

Periventricular leukomalacia (PVL), the major lesion underlying cerebral palsy in survivors of prematurity, is characterized by focal periventricular necrosis and diffuse gliosis of immature cerebral white matter. Causal roles have been ascribed to hypoxiaischemia and maternal-fetal infection, leading to cytokine responses, inflammation, and oligodendrocyte cell death. Because interferon-gamma (IFN-gamma) is directly toxic to immature oligodendrocytes, we tested the hypothesis that it is expressed in PVL (N = 13) compared to age-adjusted controls (N = 31) using immunocytochemistry. In PVL, IFN-gamma immunopositive macrophages were clustered in necrotic foci, and IFN-gamma immunopositive reactive astrocytes were present throughout the surrounding white matter (WM). The difference in the number of IFN-gamma immunopositive glial cells/high power field (IFN-gamma score, Grades 0-3) between PVL cases (age-adjusted mean 2.59+/-0.25) and controls (age-adjusted mean 1.39+/-0.16) was significant (p<0.001). In the gliotic WM, the IFN-gamma score correlated with markers for lipid peroxidation, but not nitrative stress. A subset of premyelinating (04+) oligodendrocytes expressed IFN-gamma receptors in PVL and control cases, indicating that these cells are vulnerable to IFN-gamma toxicity via receptor-mediated interactions. In PVL, IFN-gamma produced by macrophages and reactive astrocytes may play a role in cytokine-induced toxicity to premyelinating oligodendrocytes as part of a cytokine response stimulated by ischemia and/or infection.
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PMID:Interferon-gamma expression in periventricular leukomalacia in the human brain. 1577 42

Approximately 10% of newborns are born prematurely. Of these children, more than 10% will sustain neurological injuries leading to significant learning disabilities, cerebral palsy, or mental retardation, with very low birth weight infants having an even higher incidence of brain injury. Whereas intraventricular hemorrhage was the most common form of serious neurological injury a decade ago, periventricular white matter injury (PWMI) is now the most common cause of brain injury in preterm infants. The spectrum of chronic PWMI includes focal cystic necrotic lesions (periventricular leukomalacia; PVL) and diffuse myelination disturbances. Recent neuroimaging studies support that the incidence of PVL is declining, whereas diffuse cerebral white matter injury is emerging as the predominant lesion. Factors that predispose to PVL include prematurity, hypoxia, ischemia, and inflammation. It is believed that injury to oligodendrocyte (OL) progenitors contributes to the pathogenesis of myelination disturbances in PWMI by disrupting the maturation of myelin-myelin-forming oligodendrocytes. Other potential mechanisms of injury include activation of microglia and axonal damage. Chemical mediators that may contribute to white matter injury include reactive oxygen (ROS) and nitrogen species (RNS), glutamate, cytokines, and adenosine. As our understanding of the pathogenesis of PWMI improves, it is anticipated that new strategies for directly preventing brain injury in premature infants will evolve.
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PMID:Emerging concepts in periventricular white matter injury. 1569 97

Ischemia/hypoxia (I/H) causes severe perinatal brain disorders such as cerebral palsy. The neonatal brain possesses much plasticity, and to enhance new cell production would be an innovative means of therapy for such disorders. In order to elucidate the dynamic changes of neural progenitor cells in the neonatal brain after ischemia, we investigated new cells production in the subventricular zone and subsequent migration of these cells to the injured area. Newly produced cells were confirmed by incorporation of bromodeoxyuridine (BrdU), and attempt for differentiation was investigated by immunohistochemistry for molecular markers of each cellular lineage. In the sham-control brain, there were many BrdU-labeled cells which gradually decreased as the animal becomes older. Many of these cells were oligodendroglial progenitor or microglial cells. Although there were only few neuronal cells labeled for BrdU in the sham-control, they dramatically increased after I/H. They were located at just beneath the subventricular zone where the progenitor cells reside and to the injured area, indicating that newly produced cells migrated to the infarct region and differentiated into neuronal precursor cells in order to compensate the lost neural cells. We found that BrdU-labeled astroglial, oligodendroglial progenitor, and microglial cells were also increased after I/H, suggesting that they also play active roles in recovery. Progenitor cells may have potential for treating perinatal brain disorders.
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PMID:Neural precursor cells division and migration in neonatal rat brain after ischemic/hypoxic injury. 1574 71

Hypoxia-ischemia is a leading cause of morbidity and mortality in the perinatal period with an incidence of 1/4000 live births. Biochemical events such as energy failure, membrane depolarization, brain edema, an increase of neurotransmitter release and inhibition of uptake, an increase of intracellular Ca(2+), production of oxygen-free radicals, lipid peroxidation, and a decrease of blood flow are triggered by hypoxia-ischemia and may lead to brain dysfunction and neuronal death. These abnormalities can result in mental impairments, seizures, and permanent motor deficits, such as cerebral palsy. The physical and emotional strain that is placed on the children affected and their families is enormous. The care that these individuals need is not only confined to childhood, but rather extends throughout their entire life span, so it is very important to understand the pathophysiology that follows a hypoxic-ischemic insult. This review will highlight many of the mechanisms that lead to neuronal death and include the emerging area of white matter injury as well as the role of inflammation and will provide a summary of therapeutic strategies. Hypothermia and oxygen will also be discussed as treatments that currently lack a specific target in the hypoxic/ischemic cascade.
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PMID:Pathophysiology of an hypoxic-ischemic insult during the perinatal period. 1584 8

We evaluated an association of nonreassuring fetal heart rate (FHR) patterns and subsequent cerebral palsy (CP) in pregnancies with intrauterine bacterial infection. Among 10,030 infants born during 1995 to 2000, 139 were complicated with acute intrauterine bacterial infection in labor. The FHR patterns 2 hours immediately before delivery were interpreted according to the guidelines of the National Institute of Child Health and Human Development. The correlations between the FHR patterns and umbilical blood gases, as well as FHR patterns and CP were studied. Statistics included unpaired t test, contingency table with chi (2) and Fisher test, and one-way analysis of variance with Bonferroni/Dunn test. Fifteen infants (11%) developed CP at 2 years or older. Nonreassuring FHR patterns including recurrent late deceleration, severe variable deceleration, and prolonged deceleration occurred in 24% of pregnancies with intrauterine infection. Incidence of CP was not different according to the FHR deceleration patterns or umbilical pH values. Multiple logistic regression analysis revealed that fetal tachycardia (OR, 11; 95% CI, 1.8 to 67) and lower gestational age (< 34 weeks; OR, 9.4; 95% CI, 0.96 to 93) was associated with CP in intrauterine infection. Nonreassuring FHR patterns were increased in intrauterine infection. CP occurred more frequently and was associated with tachycardia and lower gestational age, but not with FHR deceleration patterns or acidemia, suggesting different pathophysiology from acute hypoxia-ischemia.
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PMID:Association of nonreassuring fetal heart rate patterns and subsequent cerebral palsy in pregnancies with intrauterine bacterial infection. 1590 11

Bacterial infection is implicated in the selective CNS white matter injury associated with cerebral palsy, a common birth disorder. Exposure to the bacterial endotoxin LPS produced death of white matter glial cells in isolated neonatal rat optic nerve (RON) (a model white matter tract), over a 180-min time course. A delayed intracellular Ca(2+) concentration ([Ca(2+)](i)) rise preceded cell death and both events were prevented by removing extracellular Ca(2+). The cytokines TNF-alpha or IL-1beta, but not IL-6, mimicked the cytotoxic effect of LPS, whereas blocking either TNF-alpha with a neutralizing Ab or IL-1 with recombinant antagonist prevented LPS cytotoxicity. Ultrastructural examination showed wide-scale oligodendroglial cell death in LPS-treated rat optic nerves, with preservation of astrocytes and axons. Fluorescently conjugated LPS revealed LPS binding on microglia and astrocytes in neonatal white and gray matter. Astrocyte binding predominated, and was particularly intense around blood vessels. LPS can therefore bind directly to developing white matter astrocytes and microglia to evoke rapid cell death in neighboring oligodendroglia via a calcium- and cytokine-mediated pathway. In addition to direct toxicity, LPS increased the degree of acute cell death evoked by ischemia in a calcium-dependent manner.
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PMID:Acute lipopolysaccharide-mediated injury in neonatal white matter glia: role of TNF-alpha, IL-1beta, and calcium. 1597 42

We developed an original rat model for neonatal brain lesions whereby we explored the sequential effects of infectious and hypoxic-ischemic aggressions. We investigated the influence of combined exposure to prenatal infection with neonatal hypoxic-ischemic insult. Infectious effect was produced by administrating lipopolysaccharide (LPS) intraperitoneally to pregnant rats starting on embryonic day 17. Hypoxia-ischemia (H/I) was induced in the pups at postnatal day 1 (P1) by ligature of the right common carotid artery followed by exposure to hypoxia (8% O(2)) for 3.5 h. Animals were randomized into four groups: (1) control group: pups born to mothers subjected to intraperitoneal saline injection; (2) LPS group: pups exposed in utero to LPS; (3) H/I group: pups exposed to postnatal hypoxia after ligation of the right carotid artery, and (4) H/I plus LPS group: in utero exposure to LPS followed by postnatal hypoxia after ligation of the right carotid artery. Neuropathological findings in pups examined at P3 and P8 showed that groups 2, 3, and 4 presented a pattern of neuronal injury similar to those characterized as 'selective neuronal necrosis' within the context of human perinatal encephalopathy. Neuronal cellular injuries were particularly seen in the neocortex, mainly in parasagittal areas. The extent of neuronal cell injury in the brain of rats exposed to postnatal H/I was significantly increased by antenatal exposure to LPS. This animal model provides an experimental means to explore the respective roles of anoxic and infectious components in the pathogenesis of perinatal brain lesions and consequent cerebral palsy.
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PMID:Neuronal injuries induced by perinatal hypoxic-ischemic insults are potentiated by prenatal exposure to lipopolysaccharide: animal model for perinatally acquired encephalopathy. 1604 47

Perinatal hypoxia-ischemia (HI) is the most common cause of cerebral palsy, and an important consequence of perinatal HI is epilepsy. Epilepsy is a disorder in which the balance between cerebral excitability and inhibition is tipped toward uncontrolled excitability. Selected neuronal circuits as well as certain populations of glial cells die from the excitotoxicity triggered by HI. Excitotoxicity, a term referring to cell death caused by overstimulation of the excitatory glutamate neurotransmitter receptors, plays a critical role in brain injury caused by perinatal HI. Ample evidence suggests distinct differences between the immature and mature brain with respect to the pathology and consequences of hypoxic-ischemic brain injury. Thus, the intrinsic vulnerability of specific cell types and systems in the developing brain is particularly important in determining the final pattern of damage and functional disability caused by perinatal HI. These patterns of neuronal vulnerability are associated with clinical syndromes of neurologic disorders such as cerebral palsy, epilepsy, and seizures. Recent studies have uncovered important molecular and cellular aspects of hypoxic-ischemic brain injury. The cascade of biochemical and histopathological events initiated by HI can extend for days to weeks after the insult is triggered, which may provide a "therapeutic window" for intervening in the pathogenesis in the developing brain. Activation of apoptotic programs accounts for the majority of HI-induced pathophysiology in neonatal brain disorders. New experimental approaches to protecting brain tissue from the effects of neonatal HI include administration of neuronal growth factors and effective inhibition of the death effector pathways, such as caspase cascade, and their downstream targets, which execute apoptosis and/or induction of their regulatory cellular proteins. Our recent findings that a novel neuronal protein, neuronal pentraxin 1 (NP1), is induced following HI in neonatal brain and that NP1 gene silencing is neuroprotective suggest that NP1 could be a new molecular target in the central neurons for preventing HI injury in developing brain. Most importantly, the specific interactions between NP1 and the excitatory glutamate receptors and their colocalization further implicate a role for this novel neuronal protein in the excitotoxic cascade. Recent experimental work suggests that these approaches may be effective during a longer therapeutic window after the insult, as they are acting on events that are relatively delayed, creating the potential for therapeutic interventions for these lifelong neurological disabilities.
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PMID:Molecular mediators of hypoxic-ischemic injury and implications for epilepsy in the developing brain. 1605 39

Infants born prematurely are prone to chronic neurologic deficits including cerebral palsy, epilepsy, cognitive delay, behavioral problems, and neurosensory impairments. In affected children, imaging and neuropathological findings demonstrate significant damage to white matter. The extent of cortical damage has been less obvious. Advances in the understanding of telencephalon development provide insights into how systemic intrauterine insults affect the developing white matter, subplate, and cortex, and lead to multiple neurologic impairments. In addition to white matter oligodendrocytes and axons, other elements at risk for perinatal brain injury include subplate neurons, GABAergic neurons migrating through white matter and subplate, and afferents of maturing neurotransmitter systems. Common insults including hypoxia-ischemia and infection often affect the developing brain differently than the mature brain, and insults precipitate a cascade of damage to multiple neural lineages. Insights from development can identify potential targets for therapies to repair the damaged neonatal brain before it has matured.
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PMID:Systemic prenatal insults disrupt telencephalon development: implications for potential interventions. 1606 21

Periventricular leukomalacia (PVL) is the major substrate of cerebral palsy in survivors of prematurity. Its pathogenesis is complex and likely involves ischemia/reperfusion in the critically ill premature infant, with impaired regulation of cerebral blood flow, as well as inflammatory mechanisms associated with maternal and/or fetal infection. During the peak period of vulnerability for PVL, developing oligodendrocytes (OLs) predominate in the white matter. We hypothesize that free radical injury to the developing OLs underlies, in part, the pathogenesis of PVL and the hypomyelination seen in long-term survivors. In human PVL, free radical injury is supported by evidence of oxidative and nitrative stress with markers to lipid peroxidation and nitrotyrosine, respectively. Evidence in normal human cerebral white matter suggests an underlying vulnerability of the premature infant to free radical injury resulting from a developmental mismatch of antioxidant enzymes (AOE) and subsequent imbalance in oxidant metabolism. In vitro studies using rodent OLs suggest that maturational susceptibility to reactive oxygen species is dependent, not only on levels of individual AOE, but also on specific interactions between these enzymes. Rodent in vitro data further suggest 2 mechanisms of nitric oxide damage: one involving the direct effect of nitric oxide on OL mitochondrial integrity and function, and the other involving an activation of microglia and subsequent release of reactive nitrogen species. The latter mechanism, while important in rodent studies, remains to be determined in the pathogenesis of human PVL. These observations together expand our knowledge of the role that free radical injury plays in the pathogenesis of PVL, and may contribute to the eventual development of therapeutic strategies to alleviate the burden of oxidative and nitrative injury in the premature infant at risk for PVL.
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PMID:Oxidative and nitrative injury in periventricular leukomalacia: a review. 1619 89


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