UMLS:C0599766 - FACTA Search

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Query: UMLS:C0599766 (functional recovery)
13,441 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanisms of myelin injury and repair were studied in acute multiple sclerosis lesions and in a murine model of demyelination induced by a virus. Injury to oligodendrocytes resulting in degeneration of inner glial loops and inner myelin lamellae (dying-back oligodendrogliopathy) was observed by electron microscopy in brain biopsies of acute demyelinating lesions. Attempts at central nervous system remyelination as manifested by thinly myelinated axons and proliferation of oligodendrocytes were observed at the edge of many acute plaques. To develop therapeutic strategies to inhibit demyelination or promote remyelination, mice infected intracranially with Theiler's virus (a picornavirus) were studied. Experimental manipulation of Theiler's virus-infected mice by treatment during chronic demyelinating disease with immunoglobulins directed at normal spinal cord antigens or with monoclonal antibodies which deplete CD4 or CD8-positive T cells resulted in augmentation of new myelin synthesis. These observations suggest that disturbances in the myelinating function of oligodendrocytes, events not accompanied by death of these cells, may be among the earliest pathological events in multiple sclerosis. Experiments using the Theiler's virus model of demyelination indicate that manipulation of the immune response has the potential to promote central nervous system remyelination and functional recovery in multiple sclerosis.
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PMID:Central nervous system demyelination and remyelination in multiple sclerosis and viral models of disease. 143 Jan 55

CNS remyelination and functional recovery often occur after experimental demyelination in adult rodents. This has been attributed to the ability of mature oligodendrocytes and/or their precursor cells to divide and regenerate in response to signals in demyelinating lesions. To determine whether oligodendrocyte precursor cells exist in the adult human CNS, we have cultured white matter from patients undergoing partial temporal lobe resection for intractable epilepsy. These cultures contained a population of process-bearing cells that expressed antigens recognized by the O4 monoclonal antibody, but these cells did not express galactocerebroside (a marker for oligodendrocytes), glial fibrillary acidic protein (a marker for astrocytes), or vimentin. Selective elimination of O4-positive (O4+) cells by complement-mediated lysis resulted in inhibition of oligodendrocyte development in vitro. Since O4+ cells have an antigenic phenotype reminiscent of the rat adult oligodendrocyte-type 2 astrocyte progenitor and appear to develop into oligodendrocytes rather than type 2 astrocytes with time in culture, we call them "pre-oligodendrocytes." Neither pre-oligodendrocytes nor oligodendrocytes incorporated 3H-thymidine in response to rat astrocyte-conditioned medium, platelet-derived growth factor, insulin-like growth factor (IGF-1), or basic fibroblast growth factor (bFGF). However, IGF-1 increased the relative abundance of oligodendrocytes to pre-oligodendrocytes, while bFGF had the opposite effect. Cells with the antigenic phenotype of pre-oligodendrocytes were also identified in tissue prints of adult human white matter. We propose that, in human demyelinating diseases such as multiple sclerosis, pre-oligodendrocytes may divide and/or migrate in response to signals present in demyelinated lesions and thus facilitate remyelination.
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PMID:Pre-oligodendrocytes from adult human CNS. 155 7

We elicited motor evoked potentials (MEPs) using transcortical magnetic stimulation in 150 control subjects aged 14 to 85 years and 275 patients with a variety of diseases. There were no significant side effects. Cortex-to-target muscle latencies measured 20.2 +/- 1.6 ms (thenar), 14.2 +/- 1.7 ms (extensor digitorum communis), 9.4 +/- 1.7 ms (biceps), and 27.2 +/- 2.9 ms (tibialis anterior). Central motor delay between the cortex and the C-7 and L-5 measured 6.7 +/- 1.2 ms and 13.1 +/- 3.8 ms, respectively. Mean spinal cord motor conduction velocity measured 65.4 m/s. MEP amplitude expressed as a percentage of the maximum M wave was never less than 20% of the M wave. A value of less than 10% is considered abnormal. MEP latency increases linearly with age and central motor delay is longer in older subjects. Compound muscle action potentials and absolute MEP amplitudes decreased linearly with age. In multiple sclerosis (MS), MEP latency and central delay were often very prolonged. The MEP was more sensitive than the SEP in MS. In amyotrophic lateral sclerosis, MEP latencies were only modestly prolonged; the characteristic abnormality was reduced amplitude. When pseudobulbar features predominated MEPs were often absent. The MEP was of normal latency in Parkinson's disease, but age-related amplitude was often increased. MEP latency and amplitude were normal in Huntington's disease. Abnormal MEPs persisted several months after stroke despite good functional recovery. The MEP could be used to advantage to demonstrate proximal conduction slowing and block in demyelinating neuropathies. In plexopathy, ability to elicit an MEP several days after onset of paresis was good evidence of neuronal continuity in motor fibers.
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PMID:AAEM minimonograph #35: Clinical experience with transcranial magnetic stimulation. 793 34

We report a case of acute multiple sclerosis in whom computed tomography (CT) scan suggested the presence of a large plaque. The anatomical and functional recovery of the brain tissue was followed by means of repeated CT scan and 123I-HIPDM studies. Single photon emission CT may be successfully employed to monitor the pathophysiological changes associated with the demyelinating process.
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PMID:Sequential computed tomography and 123I-HIPDM scans in multiple sclerosis with large plaque. A case report. 349 7

A 32-year-old woman experienced subacute onset of weakness in her left leg, urinary retention and difficulty in extending her right middle and third finger. She subsequently suffered episodes of myelopathy, optic neuritis and cerebellar ataxia over a period of several years. Brain MRI showed multiple areas of high signal intensity on T2-weighted images, consistent with multiple sclerosis (MS). However spinal MRI revealed no abnormal findings. In her most recent episode, at age 40 she developed paraparesis. Neurologic examination revealed down beat nystagmus on gazing to the right, horizontal jerk nystagmus gazing to the left, weakness of the right middle and third fingers and paraparesis associated with spasticity of the right leg. Sensory disturbance below C3 and diminished vibration and position sense in both legs were also observed. The patient could not stand or walk, and urinary disturbance was present. Spinal MRI revealed syrinx formation at the level of vertebral bodies C2 to C6. The syrinx within the cervical cord diminished in size after four months, but the patient was unable to walk unaided and had moderate sensory disturbance as before. This finding suggests that the prognosis of MS with syrinx formation following repeated episodes of myelopathy is not always favorable. We believe that functional recovery in MS with syringomyelia is affected by the severity of the demyelination and/or gliosis caused by MS rather than by the presence of the syrinx.
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PMID:[Multiple sclerosis with syringomyelia--case report]. 813 3

Brain plasticity and the mechanisms controlling plasticity are central to learning and memory as well as the recovery of function after brain injury. While it is clear that neurotrophic factors are one of the molecular classes that continue to regulate brain plasticity in the adult central nervous system (CNS), less appreciated but equally profound is the role of cell adhesion molecules (CAMs) in plasticity mechanisms such as long term potentiation, preservation of neurons and regeneration. Ironically, however, CAMs can also reorganize the extra-cellular space and cause disturbances that drive the development of brain pathology in conditions such as Alzheimer's disease and multiple sclerosis. Candidate molecules include the amyloid precursor protein which shares many properties of a classical CAM and beta-amyloid which can masquerade as a pseudo CAM. Beta-Amyloid serves as a nidus for the formation of senile plaques in Alzheimer's disease and like CAMs provides an environment for organizing neurotrophic factors and other CAMs. Inflammatory responses evolve in this environment and can initiate a vicious cycle of perpetuated neuronal damage that is medicated by microglia, complement and other factors. Certain CAMs may converge on common signal transduction pathways involving focal adhesion kinases. Thus a breakdown in the organization of key CAMs and activation of their signal transduction mechanisms may serve as a new principle for the generation of brain pathology.
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PMID:Cell adhesion molecules in neural plasticity and pathology: similar mechanisms, distinct organizations? 967 Feb 24

Remyelination enables restoration of saltatory conduction and a return of normal function lost during demyelination. Unfortunately, remyelination is often incomplete in the adult human central nervous system (CNS) and this failure of remyelination is one of the main reasons for clinical deficits in demyelinating disease. An understanding of the failure of remyelination in demyelinating diseases such as Multiple Sclerosis depends upon the elucidation of cellular events underlying successful remyelination. Although the potential for remyelination of the adult CNS has been well established, there is still some dispute regarding the origin of the remyelinating cell population. The literature variously reports that remyelinating oligodendrocytes arise from dedifferentiation and/or proliferation of mature oligodendrocytes, or are generated solely from proliferation and differentiation of glial progenitor cells. This review focuses on studies carried out on remyelinating lesions in the adult rat spinal cord produced by injection of antibodies to galactocerebroside plus serum complement that demonstrate: 1) oligodendrocytes which survive within an area of demyelination do not contribute to remyelination, 2) remyelination is carried out by oligodendrocyte progenitor cells, 3) recruitment of oligodendrocyte progenitors to an area of demyelination is a local response, and 4) division of oligodendrocyte progenitors is symmetrical and results in chronic depletion of the oligodendrocyte progenitor population in the normal white matter around an area of remyelination. These results suggest that failure of remyelination may be contributed to by a depletion of oligodendrocyte progenitors especially following repeated episodes of demyelination. Remyelination allows the return of saltatory conduction (Smith et al., 1979) and the functional recovery of demyelination-induced deficits (Jeffery et al., 1997). Findings such as these have encouraged research aimed at enhancing the limited remyelination found in Multiple Sclerosis (MS) lesions, evidenced by a rim of thin myelin sheaths around the edges of a lesion, or, in a minority of acute foci, throughout the entire lesion (Prineas et al., 1989; Raine et al., 1981). It must be said, however, that although remyelination is clearly a prerequisite to sustained functional recovery, other factors such as the state of the inflammatory response and degree of axonal survival within the demyelinated region contribute to the extent of functional recovery that may be possible following therapeutic intervention aimed at halting disease progression. It is not yet clear whether the progression of functional deficits in MS is primarily the result of an increasing load of demyelination, or axon loss, or a combination of the two processes. However, given the increasing recognition that myelin sheaths play a role in protecting axons from degeneration, the success or failure of remyelination has functional consequences for the patient. To understand why remyelination should fail in demyelinating disease and develop strategies to enhance remyelination requires an understanding of the biology of successful remyelination. Firstly, what is the origin of the remyelinating cell population in the adult CNS? Secondly, what are the dynamics of the cellular response of this population during demyelination and remyelination? And thirdly, what are the consequences to the tissue of an episode of demyelination? This review will focus on studies that address these issues, and discuss the implications of the results of these experiments for our understanding of MS and the development of therapeutic interventions aimed at enhancing remyelination.
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PMID:The role of oligodendrocytes and oligodendrocyte progenitors in CNS remyelination. 1063 29

Although multiple sclerosis (MS) is an inflammatory demyelinating disease, there can be substantial axonal injury and loss. We therefore hypothesized that adaptive cortical changes may contribute to limiting functional impairment, particularly in the early stages of the disease. To test our hypothesis, we used functional magnetic resonance imaging (MRI) to characterize the localization and volumes of activation in the motor cortex during simple flexion-extension finger movements. There were differences in the patterns of cortical activation with movement between the 12 MS patients and the 12 normal controls. All patients showed greater relative supplementary motor area activation than did the normal controls. The relative hemispheric lateralization of sensorimotor cortex (SMC) activation decreased in direct proportion to the total cerebral T2-weighted MRI hyperintense lesion load. This appeared to be due primarily to increases in ipsilateral SMC activation with increasing lesion load in white matter of the hemisphere contralateral to the limb moved. The center of activation in the contralateral SMC was shifted a mean of 8.8 mm posterior in patients relative to controls, providing additional evidence for cortical adaptive responses to injury. The magnitude of this posterior shift in the SMC activation increased with greater T2 lesion loads. These observations demonstrate that cortical recruitment for simple finger movements can change both quantitatively and qualitatively in the SMCs of MS patients, suggesting that cortical reorganization or "unmasking" of latent pathways can contribute to functional recovery. These adaptive changes are another factor potentially limiting the strength of the relationship between MRI measures of pathology and clinical measures of disability.
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PMID:The motor cortex shows adaptive functional changes to brain injury from multiple sclerosis. 1080 31

A major question in neurobiology is whether myelin repair can restore neurological function following the course of a severe, progressive CNS demyelinating disease that induces axonal loss. In this study we used Theiler's murine encephalomyelitis virus (TMEV) to induce a chronic progressive CNS demyelinating disease in mice that was immune-mediated and pathologically similar to human multiple sclerosis. Because immunosuppression of chronically TMEV-infected mice has been shown to enhance myelin repair, we first addressed the potential roles of CD4(+) and CD8(+) T cells in the inhibition of CNS remyelination during chronic disease. TMEV infection of susceptible PL/J mice deficient in CD4(+) but not CD8(+) T cells demonstrated a significant increase in severity of pathogenesis when compared with wild-type controls. This was characterized by enhanced demyelination, spinal cord atrophy, neurological deficits, and mortality. Interestingly, the PL/J CD4(-/-) mice that survived to the chronic stage of the disease had nearly complete spontaneous myelin repair mediated by both oligodendrocytes and infiltrating Schwann cells. Therefore, we next addressed whether this spontaneous myelin repair was associated with improved neurological function despite the increased pathology. Of interest, all surviving PL/J CD4(-/-) mice showed partial restoration of motor coordination and gait that coincided temporally with spontaneous myelin repair. Furthermore, functional recovery of motor coordination correlated strongly with the percentage of myelin repair mediated by Schwann cells, whereas restoration of hindlimb gait correlated with oligodendrocyte-mediated myelin repair. This is the first study to demonstrate that spontaneous remyelination correlates with partial restoration of neurological function during the course of a progressive, immune-mediated CNS demyelinating disease. Of greater importance, functional recovery occurred despite previous severe demyelination and spinal cord atrophy.
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PMID:Spontaneous remyelination following extensive demyelination is associated with improved neurological function in a viral model of multiple sclerosis. 1140 35

Multiple sclerosis is the prototype inflammatory autoimmune disorder of the central nervous system and, with a lifetime risk of one in 400, potentially the most common cause of neurological disability in young adults. As with all complex traits, the disorder results from an interplay between as yet unidentified environmental factors and susceptibility genes. Together, these factors trigger a cascade of events, involving engagement of the immune system, acute inflammatory injury of axons and glia, recovery of function and structural repair, post-inflammatory gliosis, and neurodegeneration. The sequential involvement of these processes underlies the clinical course characterised by episodes with recovery, episodes leaving persistent deficits, and secondary progression. The aim of treatment is to reduce the frequency, and limit the lasting effects, of relapses, relieve symptoms, prevent disability arising from disease progression, and promote tissue repair. Despite limited success in each of these categories, everyone touched by multiple sclerosis looks for a better dividend from applying an improved understanding of the pathogenesis to clinical management.
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PMID:Multiple sclerosis. 1195 56

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