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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The recent molecular cloning of BDNF and CNTF based on traditional protein purification and protein sequencing and the identification and cloning of NT-3 and NT-4 by homology cloning strategies has led to a tremendous flurry of interest in the biology of these proteins and initiation of studies to assess their potential utility in neurological disorders ranging through degenerative disease, stroke and ischemia, trauma and peripheral neuropathies. Tissue culture studies have been very useful in identifying neuronal specificities of the neurotrophins and CNTF and in combination with localization studies of these growth factors and their receptors have provided the basis for in vivo studies. Initial animal studies with BDNF indicate efficacy of BDNF in models of Alzheimer's and Parkinson's disease and small fiber sensory neuropathy. Studies with CNTF have similarly progressed from in vitro findings, especially the discovery that CNTF is a growth factor for motor neurons, to in vivo findings where CNTF has been shown to be effective in slowing symptoms of motor neuron dysfunction in three genetic models. Based on these positive animal data, CNTF is currently in clinical trials for the potential treatment of motor neuron disease or amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease.
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PMID:Neurotrophic growth factors and neurodegenerative diseases: therapeutic potential of the neurotrophins and ciliary neurotrophic factor. 783 3

Ciliary neurotrophic factor (CNTF) has been shown to exhibit potent neurotrophic activity on peripheral and central neurons in vitro and in vivo. However, it remains to be determined whether or not CNTF rescues neuronal loss due to focal cerebral ischemia and prevents ischemia-induced disability of space navigation in rats. In the present in vivo study, we infused CNTF continuously for 4 weeks into the lateral ventricle, starting just after permanent occlusion of the left middle cerebral artery (MCA) of stroke-prone spontaneous hypertensive rats. CNTF infusion prevented the occurrence of ischemia-induced learning disability in a dose-dependent manner in rats subjected to the Morris water maze task. Subsequent histological examinations showed that cortical infarction and retrograde degeneration of the ipsilateral thalamic neurons in ischemic rats infused with CNTF were significantly less severe than those in ischemic rats infused with vehicle alone. These findings suggest that postischemic CNTF treatment prevents the occurrence of spatial learning disability in rats with permanent MCA occlusion, possibly by reducing neuronal damage within the cerebral cortex and secondary retrograde degeneration of the thalamus.
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PMID:Ciliary neurotrophic factor attenuates spatial cognition impairment, cortical infarction and thalamic degeneration in spontaneously hypertensive rats with focal cerebral ischemia. 871 Jan 71

Amyotrophic lateral sclerosis (ALS) has become an increasingly attractive area for the pharmaceutical industry, the most experimentally tractable of the neurodegenerative diseases. Mechanisms underlying cell death in ALS are likely to be important in more common but more complex disorders. Riluzole, the only drug launched for treatment ALS is currently undergoing industrial trials for Alzheimer's, Parkinson's, Huntington disease, stroke and head injury. Other compounds in Phase III testing for ALS (mecamserin, xaliproden, gabapentin) are also in trials for other neurodegenerative disorders. Mechanisms of action of these advanced compounds are limited to glutamate antagonism, direct or indirect growth factor activity, as well as GABA agonism and interaction with calcium channels. A broader range of mechanisms is represented by compounds in Phase I trials: glutamate antagonism (dextramethorphan/p450 inhibitor; talampanel), growth factors (leukemia inhibiting factor; IL-1 receptor; encapsulated cells secreting CNTF) and antioxidants (TR500, a glutathione-repleting agent; recombinant superoxide dismutase; procysteine.) An even broader range of mechanisms is being explored in preclinical discovery programs. Recognition of the difficulties associated with delivery of protein therapeutics to the CNS has led to development of small molecules interacting either with neurotrophin receptors or with downstream intracellular signalling pathways. Other novel drug targets include caspaces, protein kinases and other molecules influencing apoptosis. High-throughput screens of large libraries of small molecules yield lead compounds that are subsequently optimized by chemists, screened for toxicity, and validated before a candidate is selected for clinical trials. The net is cast wide in early discovery efforts, only about 1% of which result in useful drugs at the end of a decade-long process. Successful discovery and development of novel drugs will increasingly depend on collaborative efforts between the academy and industry.
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PMID:Novel drug development for amyotrophic lateral sclerosis. 1109 Aug 60

Breakdown or absence of vascular oxygen delivery is a hallmark of many common human diseases, including cancer, myocardial infarction, and stroke. The chief mediator of hypoxic response in mammalian tissues is the transcription factor hypoxia-inducible factor 1 (HIF-1), and its oxygen-sensitive component HIF-1alpha. A key question surrounding HIF-1alpha and the hypoxic response is the role of this transcription factor in cells removed from a functional vascular bed; in this regard there is evidence indicating that it can act as either a survival factor or induce growth arrest and apoptosis. To study more closely how HIF-1alpha functions in hypoxia in vivo, we used tissue-specific targeting to delete HIF-1alpha in an avascular tissue: the cartilaginous growth plate of developing bone. We show here the first evidence that the developmental growth plate in mammals is hypoxic, and that this hypoxia occurs in its interior rather than at its periphery. As a result of this developmental hypoxia, cells that lack HIF-1alpha in the interior of the growth plate die. This is coupled to decreased expression of the CDK inhibitor p57, and increased levels of BrdU incorporation in HIF-1alpha null growth plates, indicating defects in HIF-1alpha-regulated growth arrest occurs in these animals. Furthermore, we find that VEGF expression in the growth plate is regulated through both HIF-1alpha-dependent and -independent mechanisms. In particular, we provide evidence that VEGF expression is up-regulated in a HIF-1alpha-independent manner in chondrocytes surrounding areas of cell death, and this in turn induces ectopic angiogenesis. Altogether, our findings have important implications for the role of hypoxic response and HIF-1alpha in development, and in cell survival in tissues challenged by interruption of vascular flow; they also illustrate the complexities of HIF-1alpha response in vivo, and they provide new insights into mechanisms of growth plate development.
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PMID:Hypoxia in cartilage: HIF-1alpha is essential for chondrocyte growth arrest and survival. 1169 37

Persephin (Pspn), a recently cloned member of the transforming growth factor-beta superfamily (TGF-beta) and glial cell line-derived neurotrophic factor (GDNF) subfamily, is distributed throughout the nervous system at extremely low levels and is thought to function as a survival factor for midbrain dopaminergic and spinal motor neurons in vivo. Here, we report that mice lacking Pspn by homologous recombination show normal development and behavior, but are hypersensitive to cerebral ischemia. A 300% increase in infarction volume was observed after middle cerebral artery occlusion. We find that glutamate-induced Ca(2+) influx, thought to be a major component of ischemic neuronal cell death, can be regulated directly by the Persephin protein (PSP) and that PSP can reduce hypoxia/reperfusion cell death in vitro. Neuronal cell death can be prevented or markedly attenuated by administration of recombinant human PSP in vivo before ischemia in both mouse and rat models. Taken together, these data indicate that PSP is a potent modulator of excitotoxicity in the central nervous system with pronounced neuroprotective activity. Our findings support the view that PSP signaling can exert an important control function in the context of stroke and glutamate-mediated neurotoxicity, and also suggest that future therapeutic approaches may involve this novel trophic protein.
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PMID:Effects of cerebral ischemia in mice deficient in Persephin. 1209 30

Activated protein C (APC) is a systemic anti-coagulant and anti-inflammatory factor. It reduces organ damage in animal models of sepsis, ischemic injury and stroke and substantially reduces mortality in patients with severe sepsis. It was not known whether APC acts as a direct cell survival factor or whether its neuroprotective effect is secondary to its anti-coagulant and anti-inflammatory effects. We report that APC directly prevents apoptosis in hypoxic human brain endothelium through transcriptionally dependent inhibition of tumor suppressor protein p53, normalization of the pro-apoptotic Bax/Bcl-2 ratio and reduction of caspase-3 signaling. These mechanisms are distinct from those involving upregulation of the genes encoding the anti-apoptotic Bcl-2 homolog A1 and inhibitor of apoptosis protein-1 (IAP-1) by APC in umbilical vein endothelial cells. Cytoprotection of brain endothelium by APC in vitro required endothelial protein C receptor (EPCR) and protease-activated receptor-1 (PAR-1), as did its in vivo neuroprotective activity in a stroke model of mice with a severe deficiency of EPCR. This is consistent with work showing the direct effects of APC on cultured cells via EPCR and PAR-1 (ref. 9). Moreover, the in vivo neuroprotective effects of low-dose mouse APC seemed to be independent of its anti-coagulant activity. Thus, APC protects the brain from ischemic injury by acting directly on brain cells.
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PMID:Activated protein C blocks p53-mediated apoptosis in ischemic human brain endothelium and is neuroprotective. 1261 68

Mesenchymal stem cells (MSC) were reported to ameliorate functional deficits after stroke in rats, with some of this improvement possibly resulting from the action of cytokines secreted by these cells. To enhance such cytokine effects, we previously transfected the telomerized human MSC with the BDNF gene using a fiber-mutant adenovirus vector and reported that such treatment contributed to improved ischemic recovery in a rat transient middle cerebral artery occlusion (MCAO) model. In the present study, we investigated whether other cytokines in addition to BDNF, i.e., GDNF, CNTF, or NT3, might have a similar or greater effect in this model. Rats that received MSC-BDNF (P < 0.05) or MSC-GDNF (P < 0.05) showed significantly more functional recovery as demonstrated by improved behavioral test results and reduced ischemic damage on MRI than did control rats 7 and 14 days following MCAO. On the other hand, rats that received MSC-CNTF or MSC-NT3 showed neither functional recovery nor ischemic damage reduction compared to control rats. Thus, MSC transfected with the BDNF or GDNF gene resulted in improved function and reduced ischemic damage in a rat model of MCAO. These data suggest that gene-modified cell therapy may be a useful approach for the treatment of stroke.
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PMID:Mesenchymal stem cells that produce neurotrophic factors reduce ischemic damage in the rat middle cerebral artery occlusion model. 1558 10

Soy phytoestrogens have been proposed as an alternative to estrogen replacement therapy and have demonstrated potential neuroprotective effects in the brain. We have shown that a high soy diet significantly reduces infarct size following permanent middle cerebral artery occlusion (MCAO). Here, we tested the hypothesis that a high soy diet would attenuate programmed cell death after stroke. Adult female Sprague-Dawley rats were ovariectomized and fed either an isoflavone-reduced diet (IFP) or a high soy diet (SP) for 2 weeks before undergoing 90 min of transient middle cerebral artery occlusion (tMCAO) followed by 22.5 h reperfusion. Infarct size, as assessed by triphenyltetrazolium chloride staining, was significantly reduced by a high soy diet (P<0.05). Apoptosis in the ischemic cortex, measured by TUNEL staining, was significantly reduced by the high soy diet. The number of active caspase-3 positive cells and caspase-mediated alpha-spectrin cleavage were also significantly decreased in the ischemic cortex of SP rats. Furthermore, nuclear translocation of apoptosis-inducing factor (AIF) was significantly reduced in the ischemic cortex of SP rats. Soy significantly increased bcl-x(L) mRNA and protein expression in the ischemic cortex compared with IFP rats. Immunohistochemistry revealed increased neuronal expression of bcl-2 and bcl-x(L) in the ischemic cortex of both IFP and SP rats following tMCAO. These results suggest that a high soy diet decreases both caspase-dependent and caspase-independent programmed cell death following tMCAO. Further, a high soy diet enhances expression of the cell survival factor bcl-x(L) following tMCAO, contributing to the neuroprotective effects of soy in the ischemic cortex.
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PMID:A high soy diet reduces programmed cell death and enhances bcl-xL expression in experimental stroke. 1770 79

AIT-082 (an analog of hypoxanthine) is an orally-active nerve growth factor (NGF) agonist under development by NeoTherapeutics as a potential treatment for Alzheimer's disease (AD), stroke and motor neuron disease. A phase II safety and efficacy trial in AD, originally scheduled to begin in the summer of 1997 [283677], began in May 1998 [286975,285562]. The study will enroll more than 60 AD patients [286975]. In February 1998, NeoTherapeutics began a phase I multiple-dose pharmacokinetic study of AIT-082 in 24 healthy elderly volunteers. Subjects of the phase I study will be administered AIT-082 once a day for 7 consecutive days at doses of 100 to 2000 mg per dose [279422]. A limited double-blind, placebo-controlled phase I/II trial in 10 AD patients commenced in Canada in the first quarter of 1997. Treatment with 4000 mg improved memory in 60% of the patients within 3 h, as determined by the word recall test. A decrease in memory was observed in 80% of placebo-treated patients [257132]. A phase I US trial, conducted by the Alzheimer's Disease Cooperative Study, with funding from the National Institute of Aging, began in July 1997. AIT-082 was administered to eight healthy, elderly volunteers as part of an escalating single-dose study. Oral administration of AIT-082 was well-tolerated at high doses [284325] AIT-082 also enhanced memory function in both young adult and aged mice within 2 h of oral administration. Prophylactic treatment prevented or delayed the onset of age-induced memory deficits in mice when administered in drinking water. When memory impairment was produced by brain lesions, the drug restored memory performance and increased the genetic expression of neurotrophin-3 (NT-3), a natural protein growth factor associated with nerve cell function [284325]. AIT-082 appears to have at least three effects on the growth of PC-12 cells in culture. Firstly, it stimulates outgrowth of neurites, secondly it potentiates the growth effects of neurotrophin, and thirdly, it stimulates the synthesis of certain neurotrophins (nerve growth factor, neurotrophin-3 and fibroblast growth factor) and pleiotrophins by astrocytes. These progrowth mechanisms are thought to form the basis of the ability of AIT-082 to restore and prevent age-related working memory deficits in mice [195438]. In October 1997, further preclinical results were presented, demonstrating that treatment with AIT-082 produced an increase in neurotrophic factors following spinal cord injury in rats. This study was conducted at NeoTherapeutics and McMaster University, and was partially funded by the Amyotrophic Lateral Sclerosis Society of Canada. After 7 days of treatment, rats with spinal cord injuries showed an increase in the levels of CNTF and BDNF, naturally occurring growth factors in the spinal cord [267514].
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PMID:AIT-082 NeoTherapeutics Inc. 1846 24

This work rests on our previous report (J Cereb Blood Flow Metab 30: 1275-1287, 2010) recognizing that glutamate (Glu) oxaloacetate transaminase (GOT) is induced when brain tissue hypoxia is corrected during acute ischemic stroke (AIS). GOT can metabolize Glu into tricarboxylic acid cycle intermediates and may therefore be useful to harness excess neurotoxic extracellular Glu during AIS as a metabolic substrate. We report that in cultured neural cells challenged with hypoglycemia, extracellular Glu can support cell survival as long as there is sufficient oxygenation. This effect is abrogated by GOT knockdown. In a rodent model of AIS, supplemental oxygen (100% O(2) inhaled) during ischemia significantly increased GOT expression and activity in the stroke-affected brain tissue and prevented loss of ATP. Biochemical analyses and in vivo magnetic resonance spectroscopy during stroke demonstrated that such elevated GOT decreased Glu levels at the stroke-affected site. In vivo lentiviral gene delivery of GOT minimized lesion volume, whereas GOT knockdown worsened stroke outcomes. Thus, brain tissue GOT emerges as a novel target in managing stroke outcomes. This work demonstrates that correction of hypoxia during AIS can help clear extracellular neurotoxic Glu by enabling utilization of this amino acid as a metabolic fuel to support survival of the hypoglycemic brain tissue. Strategies to mitigate extracellular Glu-mediated neurodegeneration via blocking receptor-mediated excitotoxicity have failed in clinical trials. We introduce the concept that under hypoglycemic conditions extracellular Glu can be transformed from a neurotoxin to a survival factor by GOT, provided there is sufficient oxygen to sustain cellular respiration.
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PMID:Oxygen-inducible glutamate oxaloacetate transaminase as protective switch transforming neurotoxic glutamate to metabolic fuel during acute ischemic stroke. 2136 30


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