Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 13 de 13
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Medicina (Kaunas) ; 58(4)2022 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-35454380

RESUMO

Unlike peripheral nerves, axonal regeneration is limited following injury to the spinal cord. While there may be reduced regenerative potential of injured neurons, the central nervous system (CNS) white matter environment appears to be more significant in limiting regrowth. Several factors may inhibit regeneration, and their neutralization can modestly enhance regrowth. However, most investigations have not considered the cytoarchitecture of spinal cord white matter. Several lines of investigation demonstrate that axonal regeneration is enhanced by maintaining, repairing, or reconstituting the parallel geometry of the spinal cord white matter. In this review, we focus on environmental factors that have been implicated as putative inhibitors of axonal regeneration and the evidence that their organization may be an important determinant in whether they inhibit or promote regeneration. Consideration of tissue geometry may be important for developing successful strategies to promote spinal cord regeneration.


Assuntos
Traumatismos da Medula Espinal , Regeneração da Medula Espinal , Axônios/fisiologia , Humanos , Regeneração Nervosa/fisiologia , Neurônios/fisiologia , Medula Espinal , Traumatismos da Medula Espinal/terapia
2.
PLoS One ; 14(9): e0216263, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31487284

RESUMO

Explants of embryonic chick sympathetic and sensory ganglia were found to exhibit asymmetric radial outgrowth of neurites under standard culture conditions with or without exogenous Nerve Growth Factor [NGF]. Opposing sides of an explant exhibited: a) differences in neurite length and, b) differences in neurite morphology. Strikingly, this asymmetry exhibited co-orientation among segregated, neighboring explants. The underlying mechanism(s) of the asymmetry and its co-orientation are not known but appear to depend on cell clustering because dissociated sympathetic neurons do not exhibit co-orientation whereas re-aggregated clusters of cells do. This emergent behavior may be similar to the community effect described in other cell types. If a similar phenomenon exists in the embryo, or in maturity, it may contribute to the establishment of proper orientation of neurite outgrowth during development and/or injury-induced neuronal plasticity.


Assuntos
Gânglios Sensitivos/citologia , Crescimento Neuronal , Cultura Primária de Células/métodos , Técnicas de Cultura de Tecidos/métodos , Animais , Embrião de Galinha
3.
Spine (Phila Pa 1976) ; 41(9): E524-9, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27128257

RESUMO

STUDY DESIGN: Intraparenchymal pressure (IPP) measurements in an in vitro cadaveric model of CNS edema. OBJECTIVE: To assess the contribution of pia mater to IPP and the effect of piotomy. SUMMARY OF BACKGROUND DATA: Multicenter randomized control trials have shown that decompression with durotomy/duroplasty significantly decreases intracranial pressure (ICP). There is a paucity of evidence regarding the effectiveness of decompression of the spinal cord by piotomy. METHODS: The supratentorial brain and spinal cord were removed from six fresh cadavers. Dura and arachnoid mater were removed. ICP monitors were placed bilaterally in the frontal and parietal lobes, and centrally in the cervical and thoracic spinal cord. To simulate edema, specimens were submerged in hypotonic solution. IPP was recorded for 5 days. A complete dorsal midline piotomy was performed on the spinal cord and resulting IPP was recorded. RESULTS: Brain and spinal cord both increased in weight. IPP significantly increased in both brain and spinal cord. The IPP increase within the spinal cord was substantially greater (averages: all four lobes = 4.0 mm Hg; cervical = 73.7 mm Hg; thoracic = 49.3 mm Hg). After piotomy, cervical and thoracic spinal cord IPP decreased immediately (avg. postpiotomy IPP = 9.7 and 10.3, respectively). CONCLUSION: There were differential effects on brain and spinal cord IPP. Brain IPP increased only slightly, possibly because of the absence of the cranium and dura mater. In contrast, spinal cord IPP increased substantially even in the absence of the laminae, dura, and arachnoid mater. Piotomy immediately and dramatically reduced spinal cord IPP. These data are consistent with the hypothesis that spinal cord IPP is primarily dependent on constraints imposed by the pia mater. Conversely, in the absence of the cranium and dura mater, the sulci may permit the pia-invested brain to better accommodate edema without significant increases in IPP. LEVEL OF EVIDENCE: N/A.


Assuntos
Edema/patologia , Modelos Neurológicos , Tecido Parenquimatoso/patologia , Pia-Máter/patologia , Medula Espinal/patologia , Idoso , Feminino , Humanos , Masculino , Tamanho do Órgão/fisiologia , Tecido Parenquimatoso/fisiologia , Pia-Máter/fisiologia , Pressão , Medula Espinal/fisiologia
4.
Spine (Phila Pa 1976) ; 40(4): E242-7, 2015 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-25423307

RESUMO

STUDY DESIGN: In vitro cadaveric study of thoracic spinal cord intramedullary pressure (IMP) in scoliotic deformity. OBJECTIVE: To define the relationship between thoracic scoliotic deformity and spinal cord IMP. SUMMARY OF BACKGROUND DATA: Clinical studies of patients with thoracic scoliosis without other spinal pathology (spinal stenosis, etc.) have rarely reported an associated thoracic myelopathy. Previous clinical and cadaveric studies of kyphosis have reported associated myelopathy and increased spinal cord IMP. We sought to determine if IMP changes in response to main thoracic scoliotic deformity. METHODS: In 6 fresh-frozen cadavers, a progressive main thoracic scoliotic deformity was created. Cadavers were positioned sitting with physiological spinal alignment, head stabilized using a skull clamp and spine segmentally instrumented from occiput to L3. The T3-T4 ligamentum flavum was removed, dura opened, and 3 pressure sensors were advanced caudally to T4-T5, T7-T8, and T10-T11 within the cord parenchyma. A step-wise main thoracic scoliotic deformity was then induced by sequentially releasing and retightening the skull clamp while coronally bending, concavity compressing, and convexity distracting posterior segmental instrumentation, allowing closure of lateral segmental osteotomies. After each step, fluoroscopic images and pressure measurements were obtained; the T4-T11 coronal Cobb angle was measured. RESULTS: Induction of main thoracic scoliosis did not significantly increase IMP. The mean main thoracic maximal scoliotic deformity created was 77° ± 2° (range: 71°-84°). At maximal deformity, the mean ΔIMP at T4-T5, T7-T8, T10-T11 was 2.2 ± 1.9 mm Hg, 1.0 ± 0.7 mm Hg, and 1.0 ± 0.8 mm Hg, respectively. CONCLUSION: In this cadaveric study, main thoracic scoliotic deformity did not significantly increase thoracic IMP. This correlates with clinical presentation such that clinical studies of patients with thoracic scoliosis without other spinal pathology have rarely reported an associated thoracic myelopathy with the thoracic scoliosis. This study helps explain the relative absence of myelopathy in isolated main thoracic coronal plane deformity. LEVEL OF EVIDENCE: 5.


Assuntos
Escoliose/complicações , Compressão da Medula Espinal/etiologia , Vértebras Torácicas/fisiopatologia , Idoso , Humanos , Pressão , Escoliose/fisiopatologia , Compressão da Medula Espinal/fisiopatologia
5.
Spine (Phila Pa 1976) ; 37(4): E224-30, 2012 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-21857404

RESUMO

STUDY DESIGN: In vitro cadaveric study of thoracic spinal cord intramedullary pressure (IMP) in kyphotic deformity. OBJECTIVE: To define the relationship between thoracic spinal kyphotic deformity and spinal cord IMP. SUMMARY OF BACKGROUND DATA: Previous studies of asymptomatic volunteers have revealed that there is wide variation in regional sagittal neutral upright thoracic spinal alignment with "normal" thoracic T4-T12 kyphosis ranging up to approximately +69° for 98.5% of the asymptomatic adult population. We sought to determine whether IMP changes in response to increasing thoracic kyphosis. METHODS: In 8 fresh-frozen cadavers, a progressive kyphotic deformity was created. Cadavers were positioned sitting with physiological thoracic kyphosis, head stabilized using a skull clamp, and spine segmentally instrumented from occiput to L2. The T3-T4 ligamentum flavum was removed, dura opened, and 3 pressure sensors were advanced caudally to T4-T5, T7-T8, and T11-T12 within the cord parenchyma. A stepwise thoracic kyphotic deformity was then induced by sequentially releasing and retightening the skull clamp while distracting posterior short segment rods and closing anterior segmental osteotomies. After each step, fluoroscopic images and pressure measurements were obtained; the T4-T12 Cobb angle was measured. RESULTS: Minor IMP increases of 2 to 5 mm Hg were observed at 1 or more spinal cord levels in 1 of 8 cadavers when the Cobb angle was less than +51° and in 4 of 8 cadavers when the angle was more than +51° and less than +63°. For Cobb angles more than +51° and less than +63°, a statistically significant, minor increase in IMP was detected at the T7-T8 level only (P = 0.02). At Cobb angles exceeding +63°, ΔIMP progressively increased at 1 or more spinal cord levels in 8 of 8 cadavers. Cobb angles ranging from +63° to +149° resulted in statistically significant increases in IMP ranging to more than 50 mm Hg. ΔIMP did not correlate with segmental spinal canal diameter (stenosis). CONCLUSION: Thoracic kyphosis less than +51° resulted in no meaningful increase in IMP, whereas kyphosis measuring +51° to +63° resulted in minor increases in IMP. After the thoracic kyphosis exceeded +63°, IMP increased significantly. ΔIMP with spinal alignment may help explain the wide range of "normal" thoracic neutral upright sagittal alignment in studies of asymptomatic adult individuals and may help further define thoracic kyphotic deformity.


Assuntos
Cifose/fisiopatologia , Pressão , Compressão da Medula Espinal/patologia , Vértebras Torácicas/anormalidades , Cadáver , Humanos , Cifose/cirurgia , Laminectomia/métodos , Compressão da Medula Espinal/fisiopatologia , Compressão da Medula Espinal/cirurgia , Vértebras Torácicas/fisiopatologia , Vértebras Torácicas/cirurgia
6.
J Neurosurg Spine ; 16(2): 195-200, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22077470

RESUMO

OBJECT: Previous studies have shown that cervical and thoracic kyphotic deformity increases spinal cord intramedullary pressure (IMP). Using a cadaveric model, the authors investigated whether posterior decompression can adequately decrease elevated IMP in severe cervical and thoracic kyphotic deformities. METHODS: Using an established cadaveric model, a kyphotic deformity was created in 16 fresh human cadavers (8 cervical and 8 thoracic). A single-level rostral laminotomy and durotomy were performed to place intraparenchymal pressure monitors in the spinal cord at C-2, C4-5, and C-7 in the cervical study group and at T4-5, T7-8, and T11-12 in the thoracic study group. Intramedullary pressure was recorded at maximal kyphosis. Posterior laminar, dural, and pial decompressions were performed while IMP was monitored. In 2 additional cadavers (1 cervical and 1 thoracic), a kyphotic deformity was created and then corrected. RESULTS: The creation of the cervical and thoracic kyphotic deformities resulted in significant increases in IMP. The mean increase in cervical and thoracic IMP (change in IMP [ΔIMP]) for all monitored levels was 37.8 ± 7.9 and 46.4 ± 6.4 mm Hg, respectively. After laminectomies were performed, the mean cervical and thoracic IMP was reduced by 22.5% and 18.5%, respectively. After midsagittal durotomies were performed, the mean cervical and thoracic IMP was reduced by 62.8% and 69.9%, respectively. After midsagittal piotomies were performed, the mean cervical and thoracic IMP was reduced by 91.3% and 105.9%, respectively. In 2 cadavers in which a kyphotic deformity was created and then corrected, the ΔIMP increased with the creation of the deformity and returned to zero at all levels when the deformity was corrected. CONCLUSIONS: In this cadaveric study, laminar decompression reduced ΔIMP by approximately 15%-25%, while correction of the kyphotic deformity returned ΔIMP to zero. This study helps explain the pathophysiology of myelopathy in kyphotic deformity and the failure of laminectomy alone for cervical and thoracic kyphotic deformities with myelopathy. In addition, the study emphasizes the need for correction of deformity during operative treatment of kyphotic deformity, the need for maintaining adequate intraoperative blood pressure during operative treatment, and the higher risk of spinal cord injury associated with operative treatment of kyphotic deformity.


Assuntos
Descompressão Cirúrgica/métodos , Dura-Máter/cirurgia , Cifose/cirurgia , Laminectomia/métodos , Pia-Máter/cirurgia , Compressão da Medula Espinal/cirurgia , Idoso , Idoso de 80 Anos ou mais , Cadáver , Vértebras Cervicais/diagnóstico por imagem , Vértebras Cervicais/cirurgia , Feminino , Humanos , Cifose/diagnóstico por imagem , Masculino , Pressão , Radiografia , Índice de Gravidade de Doença , Compressão da Medula Espinal/diagnóstico por imagem , Vértebras Torácicas/diagnóstico por imagem , Vértebras Torácicas/cirurgia
7.
Spine (Phila Pa 1976) ; 36(20): 1619-26, 2011 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-21289583

RESUMO

STUDY DESIGN: In vitro cadaveric study of cervical spinal cord intramedullary pressure (IMP) in kyphotic deformity. OBJECTIVE: To define the relationship between cervical spinal kyphotic deformity and spinal cord IMP. SUMMARY OF BACKGROUND DATA: Previous studies of asymptomatic volunteers have revealed that the greatest variation in regional sagittal neutral upright spinal alignment occurs in the cervical spine with "normal" alignment ranging up to +15 to +20° kyphosis. We sought to determine whether IMP changes in response to increasing cervical kyphosis. METHODS: In eight fresh-frozen cadavers, a progressive kyphotic deformity was created. Cadavers were positioned sitting with cervical lordosis, with head stabilized using a skull clamp. The C1 posterior arch was removed, dura was opened, and three pressure sensors were advanced caudally to C7, C4-C5, and C2 within the cord parenchyma. A stepwise kyphotic deformity was then induced by sequentially releasing and retightening the skull clamp while distracting posterior short segment rods and closing anterior segmental osteotomies. After each step, fluoroscopic images and pressure measurements were obtained. The C2-C7 Gore angle and horizontal displacement of the odontoid plumb line relative to C7 (C2-C7 sagittal vertical axis [SVA]) were measured. RESULTS: Minor IMP increases of 2 to 5 mm Hg were observed at one or more spinal cord levels in one of eight cadavers when the Gore angle was <+7.5° and in three of eight cadavers when the Gore angle was >+7.5° and <+21°. At Gore angles exceeding +21°, change in pressure (ΔIMP) progressively increased at one or more spinal cord levels in eight of eight cadavers. Gore angles ranging from +21° to +78° resulted in statistically significant increases in IMP ranging to >50 mm Hg, as did C2-C7 SVA >+75 mm. ΔIMP did not correlate with segmental spinal canal diameter (stenosis). CONCLUSION: Cervical lordosis and kyphosis less than +7.5° resulted in no meaningful increase in IMP. Minor cervical kyphosis measuring +7.5° to +21° resulted in 2 to 5 mm Hg increases in IMP. As the cervical kyphotic deformity exceeded +21°, IMP increased significantly. ΔIMP with spinal alignment may help to explain the wide range of "normal" cervical neutral upright sagittal alignment in studies of asymptomatic individuals and may help further define cervical kyphotic deformity.


Assuntos
Vértebras Cervicais/fisiopatologia , Cifose/fisiopatologia , Compressão da Medula Espinal/fisiopatologia , Medula Espinal/fisiopatologia , Espondilose/fisiopatologia , Idoso , Cadáver , Vértebras Cervicais/diagnóstico por imagem , Vértebras Cervicais/patologia , Feminino , Humanos , Cifose/complicações , Cifose/patologia , Masculino , Pressão/efeitos adversos , Radiografia , Medula Espinal/diagnóstico por imagem , Medula Espinal/patologia , Compressão da Medula Espinal/etiologia , Compressão da Medula Espinal/patologia , Espondilose/complicações , Espondilose/patologia , Transdutores de Pressão/normas
8.
Neurosurg Focus ; 28(3): E2, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20192663

RESUMO

Understanding regional as well as global spinal alignment is increasingly recognized as important for the spine surgeon. A novel software program for virtual preoperative measurement and surgical manipulation of sagittal spinal alignment was developed to provide a research and educational tool for spine surgeons. This first-generation software program provides tools to measure sagittal spinal alignment from the occiput to the pelvis, and to allow for virtual surgical manipulation of sagittal spinal alignment. The software was developed in conjunction with Clifton Labs, Inc. Photographs and radiographs were imported into the software program, and a 2D virtual spine was constructed from the images. The software then measured regional and global sagittal spinal alignment from the virtual spine construct, showing the user how to perform the measurements. After measuring alignment, the program allowed for virtual surgical manipulation, simulating surgical procedures such as interbody fusion, facet osteotomy, pedicle subtraction osteotomy, and reduction of spondylolisthesis, as well as allowing for rotation of the pelvis on the hip axis. Following virtual manipulation, the program remeasured regional and global sagittal spinal alignment. Computer software can be used to measure and manipulate sagittal spinal alignment virtually, providing a new research and educational tool. In the future, more comprehensive programs may allow for measurement and interaction in the coronal, axial, and sagittal planes.


Assuntos
Diagnóstico por Computador/métodos , Procedimentos Ortopédicos/educação , Procedimentos Ortopédicos/métodos , Cuidados Pré-Operatórios/métodos , Escoliose/diagnóstico , Escoliose/cirurgia , Software , Coluna Vertebral/cirurgia , Interface Usuário-Computador , Idoso , Articulação do Quadril/diagnóstico por imagem , Articulação do Quadril/cirurgia , Humanos , Processamento de Imagem Assistida por Computador , Vértebras Lombares/anatomia & histologia , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/cirurgia , Masculino , Radiografia , Fusão Vertebral/métodos , Coluna Vertebral/diagnóstico por imagem , Cirurgia Assistida por Computador/métodos
9.
J Spinal Disord Tech ; 22(8): 565-70, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19956030

RESUMO

STUDY DESIGN: Retrospective study of adult patients who underwent spinal surgery over a 10-year period at a single institution. OBJECTIVE: New onset postoperative paralysis remains one of the most feared complications of spinal surgery. The goal of this study was to determine the incidence and etiology of new onset major neurologic deficit immediately after adult spinal surgery. SUMMARY OF BACKGROUND DATA: Previous studies, focusing on specific disease entities, have shown incidence rates of significant spinal cord or cauda equina injury after spinal surgery ranging from approximately 0% to 2%. METHODS: The authors reviewed the quality assurance records for adult patients who underwent spinal surgery over a 10-year period (July 1, 1996 to June 30, 2006) by surgeons in the Department of Neurosurgery, University of Cincinnati College of Medicine at hospitals affiliated with the neurologic surgery residency program. Patients with new onset major neurologic deficit immediately after spinal surgery were identified. RESULTS: Of 11,817 adult spinal operations, 21 patients experienced new onset major neurologic deficit immediately after spinal surgery, yielding an overall incidence of 0.178%; in the cervical spine 0.293%, thoracic spine 0.488%, and lumbar/sacral spine 0.0745%. The difference in incidence between spinal regions was statistically significant (P = 0.00343). The etiology of the neurologic deficits was confirmed with reoperation and/or postoperative imaging studies: epidural hematoma in 8 patients, inadequate decompression in 5 patients, presumed vascular compromise in 4 patients, graft/cage dislodgement in 2 patients, and presumed surgical trauma in 2 patients. Placement of spinal instrumentation was performed in 12 of 21 patients (57.1%) and was associated with a significantly higher risk of new onset major neurologic deficit immediately after spinal surgery (P = 0.022). CONCLUSIONS: The incidence of new onset major neurologic deficit immediately after adult spinal surgery is low. Epidural hematoma and inadequate decompression were the most common etiologies in this series of patients.


Assuntos
Procedimentos Neurocirúrgicos/efeitos adversos , Procedimentos Neurocirúrgicos/mortalidade , Complicações Pós-Operatórias/mortalidade , Traumatismos da Medula Espinal/mortalidade , Doenças da Coluna Vertebral/cirurgia , Coluna Vertebral/cirurgia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Descompressão Cirúrgica/efeitos adversos , Descompressão Cirúrgica/mortalidade , Falha de Equipamento/estatística & dados numéricos , Feminino , Migração de Corpo Estranho/etiologia , Migração de Corpo Estranho/mortalidade , Hematoma Epidural Espinal/etiologia , Hematoma Epidural Espinal/mortalidade , Humanos , Incidência , Fixadores Internos/efeitos adversos , Internato e Residência/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Procedimentos Neurocirúrgicos/educação , Complicações Pós-Operatórias/etiologia , Estudos Retrospectivos , Medição de Risco , Fatores de Risco , Traumatismos da Medula Espinal/etiologia , Isquemia do Cordão Espinal/etiologia , Isquemia do Cordão Espinal/mortalidade , Fusão Vertebral/efeitos adversos , Fusão Vertebral/instrumentação , Fusão Vertebral/mortalidade , Coluna Vertebral/anatomia & histologia , Adulto Jovem
10.
Neurosurgery ; 63(3 Suppl): 25-39, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18812930

RESUMO

OBJECTIVE: In this literature review, the authors analyze data from previously published studies that evaluated neutral upright spinal alignment (NUSA) from the occiput to the pelvis in asymptomatic individuals. Based on the data for NUSA in asymptomatic volunteers, a new classification is proposed for spinal deformity. METHODS: A review of the English literature was conducted to identify studies evaluating NUSA from the occiput to the pelvis in asymptomatic juvenile, adolescent, adult, and geriatric volunteers. From the literature review, 17 angles and displacements were selected to depict neutral upright coronal and axial spinal alignment, and 21 angles and displacements were selected to depict neutral upright sagittal spinal alignment. Pooled estimates of the mean and variance were calculated for the angles and displacements from the articles that met inclusion criteria. A new classification of spinal deformity was then developed based on age-dependent NUSA; spinal abnormality; deformity curve location, pattern, magnitude, and flexibility; and global spinal alignment. RESULTS: Despite a wide variation in the regional curves from the occiput to the pelvis in asymptomatic volunteers, global spinal alignment is maintained in a narrow range for preservation of horizontal gaze and balance of the spine over the pelvis and femoral heads. CONCLUSION: A new classification of spinal deformity is proposed that provides a structure for defining deformity of all patient ages and spinal abnormalities.


Assuntos
Postura , Medula Espinal/anormalidades , Doenças da Coluna Vertebral/classificação , Adolescente , Adulto , Idoso , Humanos , Postura/fisiologia , Radiografia , Medula Espinal/diagnóstico por imagem , Doenças da Coluna Vertebral/diagnóstico por imagem
11.
J Neurosci Methods ; 168(2): 431-42, 2008 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-18164073

RESUMO

A refined battery of neurological tests, SNAP (Simple Neuroassessment of Asymmetric Impairment), was developed and validated to efficiently assess neurological deficits induced in a mouse model of traumatic brain injury. Four to 7-month old mice were subjected to unilateral controlled cortical impact or sham injury (craniectomy only). Several behavioral tests (SNAP, beam walk, foot fault, and water maze) were used to assess functional deficits. SNAP was unique among these in that it required no expensive equipment and was performed in less than 5 min per mouse. SNAP demonstrated a high level of sensitivity and specificity as determined by receiver-operator characteristics curve analysis. Interrater reliability was good, as determined by Cohen's Kappa method and by comparing the sensitivity and specificity across various raters. SNAP detected deficits in proprioception, visual fields, and motor strength in brain-injured mice at 3 days, and was sensitive enough to detect magnitude and recovery of injury. The contribution of individual battery components changed as a function of time after injury, however, each was important to the overall SNAP score. SNAP provided a sensitive, reliable, time-efficient and cost-effective means of assessing neurological deficits in mice after unilateral brain injury.


Assuntos
Lesões Encefálicas/psicologia , Córtex Cerebral/lesões , Animais , Comportamento Animal/fisiologia , Lesões Encefálicas/genética , Lesões Encefálicas/patologia , Córtex Cerebral/patologia , Doença Crônica , Interpretação Estatística de Dados , Lateralidade Funcional/fisiologia , Genótipo , Força da Mão/fisiologia , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Exame Neurológico , Variações Dependentes do Observador , Equilíbrio Postural/fisiologia , Desempenho Psicomotor/fisiologia , Reprodutibilidade dos Testes , Gravação de Videoteipe
12.
Exp Neurol ; 203(1): 95-109, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16989811

RESUMO

Axonal regeneration is normally limited after injuries to CNS white matter. Infusion of neurotrophins has been successful in promoting regenerative growth through injured white matter but this growth generally fails to extend beyond the infusion site. These observations are consistent with a chemotropic effect of these factors on axonal growth and support the prevailing view that neurotrophin-induced axonal regeneration requires the use of gradients, i.e., gradually increasing neurotrophin levels along the target fiber tract. To examine the potential of global overexpression of neurotrophins to promote, and/or modify the orientation of, regenerative axonal growth within white matter, we grafted nerve growth factor (NGF) responsive neurons into the corpus callosum of transgenic mice overexpressing NGF throughout the CNS under control of the promoter for glial fibrillary acidic protein. One week later, glial fibrillary acidic protein and chondroitin sulfate proteoglycan immunoreactivity increased within injured white matter around the grafts. NGF levels were significantly higher in the brains of transgenic compared with non-transgenic mice and further elevated within injury sites compared with the homotypic region of the non-injured side. Although there was minimal outgrowth from neurons grafted into non-transgenic mice, extensive parallel axonal regeneration had occurred within the corpus callosum up to 1.5 mm beyond the astrogliotic scar (the site of maximum NGF expression) in transgenic mice. These results demonstrate that global overexpression of neurotrophins does not override the constraints limiting regenerative growth to parallel orientations and suggest that such factors need not be presented as positive gradients to promote axonal regeneration within white matter.


Assuntos
Sistema Nervoso Central/metabolismo , Cones de Crescimento/metabolismo , Fibras Nervosas Mielinizadas/metabolismo , Fator de Crescimento Neural/metabolismo , Regeneração Nervosa/fisiologia , Fibras Simpáticas Pós-Ganglionares/metabolismo , Animais , Astrócitos/citologia , Astrócitos/fisiologia , Axotomia , Lesões Encefálicas/metabolismo , Lesões Encefálicas/fisiopatologia , Lesões Encefálicas/terapia , Lesão Encefálica Crônica/metabolismo , Lesão Encefálica Crônica/fisiopatologia , Lesão Encefálica Crônica/terapia , Sistema Nervoso Central/citologia , Proteoglicanas de Sulfatos de Condroitina/metabolismo , Cicatriz/fisiopatologia , Cicatriz/prevenção & controle , Proteína Glial Fibrilar Ácida/genética , Proteína Glial Fibrilar Ácida/metabolismo , Sobrevivência de Enxerto/fisiologia , Cones de Crescimento/ultraestrutura , Camundongos , Camundongos Transgênicos , Fibras Nervosas Mielinizadas/ultraestrutura , Fator de Crescimento Neural/genética , Regiões Promotoras Genéticas/genética , Gânglio Cervical Superior/citologia , Gânglio Cervical Superior/metabolismo , Gânglio Cervical Superior/transplante , Fibras Simpáticas Pós-Ganglionares/citologia , Fibras Simpáticas Pós-Ganglionares/transplante , Transplante de Tecidos , Regulação para Cima/fisiologia
13.
J Comput Neurosci ; 18(2): 163-81, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15714268

RESUMO

A model was developed to examine dynamical properties of regulatory motifs correlated with different temporal domains of memory. The model represents short-, intermediate-, and long-term phases of protein kinase A (PKA) activation, which appear related to corresponding phases of facilitation of the Aplysia sensorimotor synapse. The model also represents phosphorylation of the transcription factor CREB1 by PKA and consequent induction of the immediate-early gene Aplysia ubiquitin hydrolase (Ap-uch), which is essential for long-term synaptic facilitation (LTF). Simulations suggest mechanisms responsible for differing profiles of synaptic facilitation following massed vs. spaced exposures to 5-HT, and suggest a novel regulatory motif (gated positive feedback) is important for LTF. Simulations suggest zero-order ultrasensitivity may underlie a requirement of a threshold number of exposures to 5-HT for LTF induction. The model makes predictions for the dynamics of PKA activation and Ap-uch induction when MAP kinase is activated, or when repression of Ap-uch is relieved by inhibiting the transcription factor CREB2. This model may therefore be useful for understanding processes underlying memory formation in Aplysia and other systems.


Assuntos
Aplysia/fisiologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Memória/fisiologia , Modelos Biológicos , Dinâmica não Linear , Sinapses/fisiologia , Motivos de Aminoácidos/fisiologia , Animais , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico , Esquema de Medicação , Ativação Enzimática/fisiologia , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Retroalimentação , Potenciação de Longa Duração/efeitos dos fármacos , Potenciação de Longa Duração/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Fosforilação , Proteínas Repressoras/metabolismo , Serotonina/farmacologia , Sinapses/efeitos dos fármacos , Fatores de Tempo , Fatores de Transcrição/metabolismo , Ubiquitina Tiolesterase/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...