Experimental neurology
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Experimental neurology · Feb 2000
Nerve guides seeded with autologous schwann cells improve nerve regeneration.
This study evaluates the ability of Schwann cells (SCs) transplanted into a nerve guide to improve regeneration and reinnervation after sciatic nerve resection and repair, leaving a 6-mm gap, in the mouse. SCs were isolated from predegenerated adult sciatic nerves and expanded in culture using a chemically defined medium. Syngeneic, isogeneic, and autologous SCs were suspended in Matrigel and seeded in resorbable, permeable poly(l-lactide-co-epsilon-caprolactone) guides at 150,000 cells/tube. ⋯ Syngeneic SCs did not improve regeneration with respect to acellular guides. Prelabeled transplanted SCs were found to survive into the guide 1-3 months after implantation, to a larger number when they were autologous than syngeneic. Cellular prostheses composed of a resorbable guide seeded with autologous SCs appear as an alternative for repairing long gaps in injured nerves, approaching the success of autografts.
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Experimental neurology · Feb 2000
Continuous infusion of cyclosporin A postinjury significantly ameliorates cortical damage following traumatic brain injury.
Traumatic brain injury (TBI) results in the rapid necrosis of cortical tissue at the site of injury. In the ensuing hours and days, secondary injury exacerbates the original damage resulting in significant neurological dysfunction. Recent reports from our lab demonstrate that a bolus injection of the immunosuppressant cyclosporin A (CsA) is neuroprotective following TBI. ⋯ All animals receiving CsA demonstrated a significant reduction in lesion volume, with the highest dose offering the most neuroprotection (74% reduction in lesion volume). These results extend our previous findings and demonstrate that chronic infusion of CsA is neuroprotective following TBI. These findings also suggest that the mechanisms responsible for tissue necrosis following TBI are amenable to manipulation.
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Experimental neurology · Jan 2000
Light and confocal microscopic studies of evolutionary changes in neurofilament proteins following cortical impact injury in the rat.
Previous studies have shown that traumatic brain injury (TBI) produces progressive degradation of cytoskeletal proteins including neurofilaments (e.g., neurofilament 68 [NF68] and neurofilament 200 [NF200]) within the first 24 h after injury. Thus, we employed immunofluorescence (light and confocal microscopy) to study the histopathological correlates of progressive neurofilament protein loss observed at 15 min, 3 h, and 24 h following unilateral cortical injury in rats. TBI produced significant alterations in NF68 and NF200 immunolabeling in dendrites and cell bodies at contusion sites ipsilateral to injury, as well as in the noncontused contralateral cortex. ⋯ Moreover, changes in dendritic cytoskeletal proteins are progressive and not fully expressed within the first 15 min following impact injury. These progressive dendritic disruptions are characterized by disturbances in the morphology of neurofilament proteins, resulting in fragmentation and focal loss of NF68 immunofluorescence within apical dendrites. In contrast, alterations in axonal cytoskeletal proteins are more restricted and delayed with no pronounced changes until 24 h after injury.
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Experimental neurology · Jan 2000
Effects of spinal cord X-irradiation on the recovery of paraplegic rats.
Axonal regrowth is limited in the adult CNS, especially in the spinal cord, one of the major sites of traumatic lesions. Pathophysiological changes occurring after spinal cord injury include complex acute, subacute, and late processes. In this study, we assessed whether X-irradiation interferes with the acute/subacute phases, thereby improving the functional recovery of paraplegic animals. ⋯ There was a 23% less lesion-induced syringomyelia in the 2-Gy group than in the other groups (LNI and 5-20 Gy). Thus, low doses of X-rays may interfere with the formation of syringomyelia and glial scar, thereby facilitating the recovery of paraplegic animals. These findings suggest that low-dose irradiation of the lesion site, in association with other therapies, is a potentially promising treatment for improving recovery after spinal cord injury.
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Experimental neurology · Jan 2000
Sciatic nerve transection in the adult rat: abnormal EMG patterns during locomotion by aberrant innervation of hindleg muscles.
The effects of lesions in the sciatic nerve were studied in adult rats. In the left hindleg, a segment 12 mm long was resected from the proximal part of the nerve, before the bifurcation into the peroneal and tibial nerves. This segment in a reversed orientation was used as a nerve graft. ⋯ Neuronal diameters were slightly decreased but a considerable decrease was observed in dendritic branching and dendrite bundles in the pools of the SOL and in the GC were absent. No consistent trends in neuronal numbers at the affected side in comparison to the right side were detected. We conclude that axons, sprouting from the proximal stump of the sciatic nerve, innervate the muscles aselectively and that the motoneurons of origin maintain their original activation pattern.