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

Three reparative strategies based on transfer of genes, molecules, or cells to the central nervous system are reviewed. When neurons are already lost, they can sometimes be replaced by transfer to the target area of neurons or other cells compensating for the lost functions. This technique is undergoing clinical trials in Parkinson's disease. Before neurons have died, it may be possible to prevent "stressed" neurons from dying, and stimulate nerve terminal ramifications from remaining neurons using treatment with neurotrophic factors. Such approaches, with an emphasis on the NGF family of neurotrophins and their receptors, are reviewed. Finally, advances of molecular biology techniques suggest that it should be possible to transfer genes directly into non-dividing cells of the central nervous system. The three different approaches all aim at long-lasting counteractive and reparative measures in the central nervous system. It is predicted that they have general applicability, and may become important not only in neurodegenerative diseases, but also in other common afflictions of the nervous system such as ischaemia, stroke and injury.
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PMID:Reparative strategies in the brain: treatment strategies based on trophic factors and cell transfer techniques. 810 97

Several cellular signaling systems have been implicated in the neuronal death that occurs both in development ("natural" cell death) or in pathological conditions such as stroke and Alzheimer's disease (AD). Here we consider the possibility that neuronal degeneration in an array of disorders including stroke and AD arises from one or more alterations in calcium-regulating systems that result in a loss of cellular calcium homeostasis. A long-standing hypothesis of neuronal injury, the excitatory amino acid (EAA) hypothesis, is revisited in light of new supportive data concerning the roles of EAAs in stroke and the neurofibrillary degeneration in AD. Two quite new concepts concerning mechanisms of neuronal injury and death are presented, namely: 1) growth factors normally "stabilize" intracellular free calcium levels ([Ca2+]i) and protect neurons against ischemic/excitotoxic injury, and 2) aberrant processing of beta-amyloid precursor protein (APP) can cause neurodegeneration by impairing a neuroprotective function of secreted forms of APP (APPs) which normally regulate [Ca2+]i. Altered APP processing also results in the accumulation of beta-amyloid peptide which contributes to neuronal damage by destabilizing calcium homeostasis; in AD beta-amyloid peptide may render neurons vulnerable to excitotoxic conditions that accrue with increasing age (e.g., altered glucose metabolism, ischemia). Growth factors may normally protect neurons against the potentially damaging effects of calcium influx resulting from energy deprivation and overexcitation. For example, bFGF, NGF and IGFs can protect neurons from several brain regions against excitotoxic/ischemic insults. Growth factors apparently stabilize [Ca2+]i by several means including: a reduction in calcium influx; enhanced calcium extrusion or buffering; and maintenance or improvement of mitochondrial function. For example, bFGF can suppress the expression of a N-methyl-D-aspartate (NMDA) receptor protein that mediates excitotoxic damage in hippocampal neurons. Growth factors may also prevent the loss of neuronal calcium homeostasis and the increased vulnerability to neuronal injury caused by beta-amyloid peptide. Since elevated [Ca2+]i can elicit cytoskeletal alterations similar to those seen in AD neurofibrillary tangles, we propose that neuronal damage in AD results from a loss of calcium homeostasis. The data indicate that a variety of alterations in [Ca2+]i regulation may contribute to the neuronal damage in stroke and AD, and suggest possible means of preventing neuronal damage in these disorders.
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PMID:Altered calcium signaling and neuronal injury: stroke and Alzheimer's disease as examples. 851 77

Treatment strategies based on transfer of genes, molecules, or cells to the central nervous system are summarized. When neurons are already degenerated, functional compensation can be effected by grafts of syngeneic or allogenic tissue to the target area. This technique is undergoing clinical trials in Parkinson's disease. Before degeneration has occurred, it may be possible to rescue "stressed" neurons, and stimulate terminal outgrowth using treatment with neurotrophic factors. Such approaches, with an emphasis on the NGF family of neurotrophins and their receptors, are reviewed. Finally, new molecular biology techniques may permit the transfer of genes directly into non-dividing cells of the central nervous system. These three approaches may have a more general applicability, and become important not only in neurodegenerative diseases, but also in other afflictions of the nervous system such as ischemia, stroke and injury.
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PMID:Treatment strategies for neurodegenerative diseases based on trophic factors and cell transplantation techniques. 926 9

NGF (nerve growth factor) and BDNF (brain-derived neurotrophic factor) are protein molecules (MW 26 and 13.6 kDa, respectively) that are neuroprotective in the middle cerebral artery occlusion (MCAO) rat stroke model. Their mechanism of action involves the activation of transcription factor AP-1 that turns on neuronal growth genes. In our ongoing studies we are designing short peptides that mimic some of the properties of full-length neurotrophic factors. We have synthesized a neuroprotective 14-amino acid peptide (CMX-9236) with an N-terminal docosahexaenoic acid (DHA). DHA enhances entry through the blood-brain barrier. Using primary rat brain cortical cultures and a fluorescent assay we found that CMX-9236 can counteract the excitotoxic effects of glutamate or kainate, reversing the intracellular accumulation of Ca(2+) to normal levels. Administration (i.v.) of CMX-9236 post initiation of ischemia reduced the lesion volumes from 178+/-50 to 117+/-55 mm(3) in the temporary rat MCAO model (90 min), and from 216+/-58 to 127+/-57 mm(3) in the permanent (24 h) model for stroke, corresponding to 34+/-28% (P=0.01) and 41+/-19% (P=0.038) reductions of the infarct volumes. Neurological behavior scores showed 57 and 47% improvements for treated temporary and permanent models, respectively. Dose-response studies indicated a 60-fold activation of AP-1 transcription factor in cells treated with 100 ng/ml of the peptide. These studies illustrate that a small peptide can function as a neuroprotective agent and an activator of a beneficial signal transduction pathway.
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PMID:Neuroprotective effects of a new synthetic peptide, CMX-9236, in in vitro and in vivo models of cerebral ischemia. 1256 Jan 27

Death receptors (DRs) are a growing family of transmembrane proteins that can detect the presence of specific extracellular death signals and rapidly trigger cellular destruction by apoptosis. Eight human DRs (Fas, TNF-R1, TRAMP, TRAIL-R1, TRAIL-R2, DR-6, EDA-R and NGF-R) have been identified. The best studied to date is Fas (CD95). Expression and signaling by Fas and its ligand (FasL, CD95L) is a tightly regulated process essential for key physiological functions in a variety of organs, including the maintenance of immune homeostasis. Recently, strong evidence has shown that dysregulation of Fas expression and/or signaling contributes to the pathogenesis of tissue destructive diseases such as graft-versus-host disease, toxic epidermal necrolysis, multiple sclerosis and stroke. With these new developments, strategies for modulating the function of Fas signaling have emerged and provided novel protein-based therapeutic possibilities that will be discussed herein. Selective triggering of DR-mediated apoptosis in cancer cells is an emerging approach that is being intensely investigated as a mode of cancer therapy. Local administration of Fas agonists, and more promisingly, systemic use of soluble recombinant forms of TRAIL have shown efficacy in preclinical models of the disease. Developments in this field that may have important clinical implications for the treatment of cancer are reviewed.
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PMID:Protein-based therapeutic approaches targeting death receptors. 1265

Recent studies have highlighted that female sex hormones represent potential neuroprotective agents against damage produced by acute and chronic injuries in the adult brain. Clinical reports have documented the effectiveness of estrogens to attenuate symptoms associated with Parkinson's disease, and to reduce the risk of Alzheimer's disease and cerebrovascular stroke. This evidence is corroborated by numerous experimental studies documenting the protective role of female sex hormones both in vitro and in vivo. Accordingly, estrogens have been shown to promote survival and differentiation of several neuronal populations maintained in culture, and to reduce cell death associated with excitotoxicity, oxidative stress, serum deprivation or exposure to beta-amyloid. The neuroprotective effects of estrogens have been widely documented in animal models of neurological disorders, such as Alzheimer's and Parkinson's diseases, as well as cerebral ischemia. Although estrogens are known to exert several direct effects on neurones, the cellular and molecular mechanisms implicated in their protective actions on the brain are not completely understood. Thus, on the basis of clinical and experimental evidence, in this review, we discuss recent findings concerning the neuronal effects of estrogens that may contribute to their neuroprotective actions. Both estrogen receptor-dependent and -independent mechanisms will be described. These include modulation of cell death regulators, such as Bcl-2, Akt and calpain, as well as interaction with growth factors, such as BDNF, NGF, IGF-I and their receptors. The anti-inflammatory effects of estrogens will also be described, namely their ability to reduce brain levels of inflammatory mediators, cytokines and chemokines. Finally, a brief overview about receptor-independent mechanisms of neuroprotection will aim at describing the antioxidant effects of estrogens, as well as their ability to modulate neurotransmission.
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PMID:From clinical evidence to molecular mechanisms underlying neuroprotection afforded by estrogens. 1596 77

Recent studies revealed a role of natural neurotrophic IgG autoantibodies (NNAA) in the trophic supply of nervous tissue and modification ability of neuronal networks. Changes of the NNAA level likely may reflect direction (compensation, decompensation) of cytochemical and morphologic alterations of nervous tissue in acute focal ischemia, thus, having certain prognostic value. To assess the dynamics of NNAA in the blood serum on 3, 7, 14 and 21 days after ischemic stroke and 3 months after the disease, 84 patients (mean age 68+/-10 years) with first-ever stroke in the system of internal carotid artery were studied. NNAA immunoreactivity to four nervous tissue proteins, S100b, GRAP, MP-65, NGF, was conducted using ELIZA method. Patients' outcomes were assessed with the Barthel Index and NIH on the 3rd month of the disease. In the acute period of stroke, the changes of immunoreactivity, comparing to controls, were found in 95% o cases (p<0,01), the level of NNAA pathologically increased or decreased. The increase of NNAA level was revealed in 45 patients (56% cases) with satisfactory clinical rehabilitation on 7-14 days (p<0,0001) with the following normalization of these parameters to the 21st day. In case of unfavorable outcomes, the prolonged increase of the NNAA level or decrease of immunoreactivity (p<0,0001) was found in 44% of cases. The changes of NNAA level were observed in 60 patients on the 3rd month of the disease, i.e. the protracted decrease of immunoreactivity was found in 42 patients and increase - in 18 cases (p<0,01). The quantitative changes of NNAA likely indicate the adaptive-compensative reaction of the immune system. The character of immunoreactivity changes is related to reparative neuroplasticity and may be of prognostic value.
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PMID:[Natural neurotrophic IgG autoantibodies in the blood serum of patients with different clinical outcomes after ischemic stroke]. 1842 21

This study was aimed to assess whether ex vivo treatment with granulocyte-colony stimulating factor (G-CSF) modifies biological properties of bone marrow stromal cells (BMSC) and enhances functional recovery by BMSC transplantation into infarct brain. Immunohistochemistry was conducted to characterize the cultured BMSC. The pharmacological effects of G-CSF on their proliferation, cell cycle, and growth factor production were precisely analyzed, using FACS and ELISA techniques. Non-treated or G-CSF treated BMSC were stereotactically transplanted into the mice brain subjected to cerebral infarct, and its effects on functional and histological aspects were evaluated. The BMSC expressed the receptor for G-CSF. Treatment with 0.1muM of G-CSF significantly enhanced the proliferation of BMSC by increasing their population in S phase, and increased their production of SDF-1alpha, HGF, and NGF. When transplanted into infarct brain, G-CSF treated BMSC significantly improved motor function as early as 2 weeks after transplantation, whereas non-treated BMSC did 4 weeks after transplantation. These findings strongly suggest that G-CSF may enhance the proliferation and growth factor production of the cultured BMSC and accelerate functional restoration by BMSC transplantation. Such pharmacological "activation" of the BMSC may contribute to successful clinical application of BMSC transplantation therapy for ischemic stroke.
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PMID:Synergistic effects of granulocyte-colony stimulating factor on bone marrow stromal cell transplantation for mice cerebral infarct. 1928 90

We recently demonstrated that blood-brain barrier permeabilization using mannitol enhances the therapeutic efficacy of systemically administered human umbilical cord blood (HUCB) by facilitating the entry of neurotrophic factors from the periphery into the adult stroke brain. Here, we examined whether the same blood-brain barrier manipulation approach increases the therapeutic effects of intravenously delivered HUCB in a neonatal hypoxic-ischaemic (HI) injury model. Seven-day-old Sprague-Dawley rats were subjected to unilateral HI injury and then at day 7 after the insult, animals intravenously received vehicle alone, mannitol alone, HUCB cells (15k mononuclear fraction) alone or a combination of mannitol and HUCB cells. Behavioural tests at post-transplantation days 7 and 14 showed that HI animals that received HUCB cells alone or when combined with mannitol were significantly less impaired in motor asymmetry and motor coordination compared with those that received vehicle alone or mannitol alone. Brain tissues from a separate animal cohort from the four treatment conditions were processed for enzyme-linked immunosorbent assay at day 3 post-transplantation, and revealed elevated levels of GDNF, NGF and BDNF in those that received HUCB cells alone or when combined with mannitol compared with those that received vehicle or mannitol alone, with the combined HUCB cells and mannitol exhibiting the most robust neurotropic factor up-regulation. Histological assays revealed only sporadic detection of HUCB cells, suggesting that the trophic factor-mediated mechanism, rather than cell replacement per se, principally contributed to the behavioural improvement. These findings extend the utility of blood-brain barrier permeabilization in facilitating cell therapy for treating neonatal HI injury.
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PMID:Mannitol facilitates neurotrophic factor up-regulation and behavioural recovery in neonatal hypoxic-ischaemic rats with human umbilical cord blood grafts. 2056 76

Identification of functional molecules in the brain related to improvement of the degree of paralysis or increase of activities will contribute to establishing a new treatment strategy for stroke rehabilitation. Hence, protein expression changes in the cerebral cortex of rat groups with/without voluntary exercise using a running wheel after cerebral infarction were examined in this study. Motor performance measured by the accelerated rotarod test and alteration of protein expression using antibody microarray analysis comprised 725 different antibodies in the cerebral cortex adjacent to infarction area were examined. In behavioral evaluation, the mean latency until falling from the rotating rod in the group with voluntary exercise for five days was significantly longer than that in the group without voluntary exercise. In protein expression profile, fifteen proteins showed significant quantitative changes after voluntary exercise for five days compared to rats without exercise. Up-regulated proteins were involved in protein phosphorylation, stress response, cell structure and motility, DNA replication and neurogenesis (11 proteins). In contrast, down-regulated proteins were related to apoptosis, cell adhesion and proteolysis (4 proteins). Additional protein expression analysis showed that both growth-associated protein 43 (GAP43) and phosphorylated serine41 GAP43 (pSer41-GAP43) were significantly increased. These protein expression changes may be related to the underlying mechanisms of exercise-induced paralysis recovery, that is, neurite formation, and remodeling of synaptic connections may be through the interaction of NGF, calmodulin, PKC and GAP43. In the present study at least some of the participation of modulators associated with the improvement of paralysis might be detected.
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PMID:Alteration of protein expression profile following voluntary exercise in the perilesional cortex of rats with focal cerebral infarction. 2189 Jan 13


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