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The recurrent laryngeal nerve is a bilateral branch of the vagus nerve that is mainly associated with the motor innervation of the intrinsic muscles of the larynx. Despite its bilateral distribution, the right and left recurrent laryngeal nerves display unequal length due to embryological processes related to the development of the aortic arches. This length asymmetry leads to theories about morphological compensations to provide symmetrical functions to the intrinsic muscles of the larynx. In this study we investigated the developmental and cross-sectional morphometrics of the recurrent laryngeal nerves in human fetuses. Fifteen stillbirth fetuses donated to anatomical and medical research were used for investigation. Fetuses had intrauterine age ranging from 30 to 40 weeks estimated by biometry methods. Specialized anatomical dissection of the visceral block of the neck was performed to prepare histological samples of the recurrent laryngeal nerves in its point of contact with the larynx, and morpho-quantitative techniques were applied to evaluate the epineurium and perineural space of the recurrent laryngeal nerves. No statistical difference in the cross-sectional morphology of the epineurium and perineural space between right and left recurrent laryngeal nerves intra-individually was confirmed, however, we found evidence that these structures are under greater development in the left recurrent laryngeal nerve during 30 to 40 weeks of intrauterine life. Our data suggest that the nerves are under morphological development that possibly set the stage for accommodation of larger diameter and myelinization of the left recurrent laryngeal nerve during post-natal life.
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Extensive damage to peripheral nerves is a health problem with few therapeutic alternatives. In this context, the development of tissue engineering seeks to obtain materials that can help recreate environments conducive to cellular development and functional repair of peripheral nerves. Different hydrogels have been studied and presented as alternatives for future treatments to emulate the morphological characteristics of nerves. Along with this, other research proposes the need to incorporate electrical stimuli into treatments as agents that promote cell growth and differentiation; however, no precedent correlates the simultaneous effects of the types of hydrogel and electrical stimuli. This research evaluates the neural differentiation of PC12 cells, relating the effect of collagen, alginate, GelMA, and PEGDA hydrogels with electrical stimulation modulated in four different ways. Our results show significant correlations for different cultivation conditions. Electrical stimuli significantly increase neural differentiation for specific experimental conditions dependent on electrical frequency, not voltage. These backgrounds allow new material treatment schemes to be formulated through electrical stimulation in peripheral nerve tissue engineering.
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INTRODUCTION: The subgemmal neurogenous plaque is a well-defined subepithelial neural plexus associated with taste buds, located within foliate, fungiform, and circumvallate papillae of the human tongue, that is poorly known by dentists and medical professionals. The hyperplasia of subgemmal neurogenous plaque may occur and it manifests as a papule, nodule, plaque, or ulcer in the lateral posterior border of the tongue inducing the overdiagnosis of reactive, cystic, or neoplastic lesions. The aims of this study are to report a case of a patient with subgemmal neurogenous plaque, and to provide a comprehensive review of other subgemmal neurogenous plaque in the posterolateral tongue with challenging diagnosis. PRESENTATION OF CASE: A 28-year-old female with a little yellowish nodule, asymptomatic, located in posterior left lateral border of the tongue. Accurate diagnosis was based in excisional biopsy and histopathological examination showing a superficial neurofibroma-like pattern, and a neuroma-like in the deep zone. The final diagnosis was subgemmal neurogenous plaque. DISCUSSION: The subgemmal neurogenous plaque has an erythematous nodule or papule in the border of the tongue that are frequently misdiagnosis as foliate papillitis and lymphoepithelial cyst. Despite the subgemmal neurogenous plaque be considered a normal structure, the biopsy is recommended for differential diagnosis with other benign or malignant lesions in tongue. CONCLUSION: Contributing with the dentists and medical professionals in their clinical practice, we reviewed the literature and added a case of subgemmal neurogenous plaque in the posterolateral region of the tongue, highlighting the importance of its recognition to avoid misdiagnosis.
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OBJECTIVE: To quantify the neural elements in the posterior cruciate ligament (PCL) in healthy knees and with primary osteoarthrosis (OA). METHODS: In two groups with OA, one of cadavers and another of individuals, the area of neural elements identified in histological sections of PCL with anti-S100 immunohistochemistry was quantified. RESULTS: The overall mean area of the neural elements was 0.96% ± 0.67%, with the value in the cadaver group of 1.02% ± 0.67% and in the OA group of 0.80% ± 0.64%, with a significant statistically difference (p = 0.001). No correlation was observed between neural element quantification and the age of the individuals (p > 0.05). There was no difference in the quantification of neural elements between the sexes in the cadaver group (p = 0.766), but in the OA group there was a statistically significant reduction in males (p = 0.003). Also, in the osteoarthrosis group there was no difference in the quantification of neural elements in the knees with varus or valgus alignment (p = 0.847). CONCLUSION: There was a decrease in neural element quantification in PCL of individuals affected by OA in relation to non-arthritic individuals, with this quantification not related to age or with the axis of the lower limb. However, this quantification is not related to age or the axis of the lower limb. Level of Evidence III, Case control study.
OBJETIVO: Quantificar os elementos neurais no ligamento cruzado posterior (LCP) em joelhos hígidos e com osteoartrose primária (OA). MÉTODOS: Em um grupo de cadáveres e outro de indivíduos com ao, foi realizada a quantificação da área dos elementos neurais identificados em cortes histológicos do LCP com imunohistoquímica anti-S100. RESULTADOS: A média geral da área dos elementos neurais foi 0,96% ± 0,67%, com o valor no grupo cadáver de 1,02% ± 0,67% e no grupo OA de 0,80% ± 0,64%, havendo uma diferença estatisticamente significante (p = 0,001). Não se observou correlação entre a quantificação dos elementos neurais e a idade dos indivíduos (p > 0,05). Não se observou diferença na quantificação dos elementos neurais entre os sexos no grupo cadáver (p = 0,766), mas no grupo OA se observou redução estatisticamente significante no sexo masculino (p = 0,003). No grupo OA não houve diferença na quantificação dos elementos neurais nos joelhos com alinhamento varo ou valgo (p = 0,847). CONCLUSÃO: Foi demonstrada uma redução na quantificação dos elementos neurais no LCP de indivíduos acometidos por OA em relação aos indivíduos não artrósicos, com essa quantificação não tendo relação com idade nem com o eixo do membro inferior. Nível de evidência III, Estudo de caso controle.
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ABSTRACT Objective: To quantify the neural elements in the posterior cruciate ligament (PCL) in healthy knees and with primary osteoarthrosis (OA). Methods: In two groups with OA, one of cadavers and another of individuals, the area of neural elements identified in histological sections of PCL with anti-S100 immunohistochemistry was quantified. Results: The overall mean area of the neural elements was 0.96% ± 0.67%, with the value in the cadaver group of 1.02% ± 0.67% and in the OA group of 0.80% ± 0.64%, with a significant statistically difference (p = 0.001). No correlation was observed between neural element quantification and the age of the individuals (p > 0.05). There was no difference in the quantification of neural elements between the sexes in the cadaver group (p = 0.766), but in the OA group there was a statistically significant reduction in males (p = 0.003). Also, in the osteoarthrosis group there was no difference in the quantification of neural elements in the knees with varus or valgus alignment (p = 0.847). Conclusion: There was a decrease in neural element quantification in PCL of individuals affected by OA in relation to non-arthritic individuals, with this quantification not related to age or with the axis of the lower limb. However, this quantification is not related to age or the axis of the lower limb. Level of Evidence III, Case control study.
RESUMO Objetivo: Quantificar os elementos neurais no ligamento cruzado posterior (LCP) em joelhos hígidos e com osteoartrose primária (OA). Métodos: Em um grupo de cadáveres e outro de indivíduos com ao, foi realizada a quantificação da área dos elementos neurais identificados em cortes histológicos do LCP com imunohistoquímica anti-S100. Resultados: A média geral da área dos elementos neurais foi 0,96% ± 0,67%, com o valor no grupo cadáver de 1,02% ± 0,67% e no grupo OA de 0,80% ± 0,64%, havendo uma diferença estatisticamente significante (p = 0,001). Não se observou correlação entre a quantificação dos elementos neurais e a idade dos indivíduos (p > 0,05). Não se observou diferença na quantificação dos elementos neurais entre os sexos no grupo cadáver (p = 0,766), mas no grupo OA se observou redução estatisticamente significante no sexo masculino (p = 0,003). No grupo OA não houve diferença na quantificação dos elementos neurais nos joelhos com alinhamento varo ou valgo (p = 0,847). Conclusão: Foi demonstrada uma redução na quantificação dos elementos neurais no LCP de indivíduos acometidos por OA em relação aos indivíduos não artrósicos, com essa quantificação não tendo relação com idade nem com o eixo do membro inferior. Nível de evidência III, Estudo de caso controle.
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RESUMEN El propósito de este artículo es ayudar a los dentistas clínicos a identificar la neurofibromatosis tipo 1 y sus variantes. Presentamos un caso raro de un hombre de 68 años, afectado desde la infancia por la presencia de nódulos generalizados en todo el cuerpo, provocando deformaciones estéticas. Curiosamente, el impacto en la cavidad oral no fue significativo, con nódulos solo en la encía, un área de manifestación raro. La radiografía panorámica mostró un ligero agrandamiento del canal mandibular. Tras un año de seguimiento, el paciente falleció por complicaciones cardiovasculares provocadas por el síndrome.
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From December 1999 to May 2015, five patients with nerve tumors were sent to Lauro de Souza Lima Institute. It was suspected that they suffered from primary neural leprosy towards the tuberculoid clinical form, a prevalence of 4.5:10000 among the new patients assessed during the study period. All of the patients had similar clinical conditions characterized by mononeuropathy with nerve tumor associated with pain, absence of skin lesions and positive Mitsuda reaction. The authors report the main clinical characteristics and complementary tests: immunologic investigation of Mitsuda's reaction and the antigen Phenolic GlicoLipid-1 test (PGL-1), bacilloscopic index, neurophysiologic study and image procedures. All patients were submitted to tumor resection and anatomopathological study. Four out of the five patients were diagnosed with peripheral nerve tumor (one of them with malignant schwannoma, two of them with benign schwannomas and the other with neural fibrolipoma), whereas the fifth patient was diagnosed with tuberculoid leprosy.
No período de dezembro de 1999 a maio de 2015, foram encaminhados ao Instituto Lauro de Souza Lima (ILSL) cinco pacientes com tumoração em nervos suspeitos de hanseníase neural primária (HPN) da forma clinica tuberculoide, uma prevalência de 4,5/10000 entre os casos novos atendidos nesse período. Todos os pacientes apresentavam quadro clínico semelhante caracterizado por mononeuropatia com tumoração do nervo associada à dor, ausência de lesões de pele e reação de Mitsuda positiva. Os autores relatam as principais características clinicas e os exames complementares: investigação imunológica da reação de Mitsuda e o teste do antigeno Glicolipídeo-Fenólico-1, índice baciloscópico, avaliação neurofisiológica e estudos de imagem. Todos os pacientes foram submetidos a ressecção cirúrgica do tumor e estudo anatomopatológico. Dentre os cinco pacientes, quatro foram diagnosticados como tumor de nervo periférico (um Schwannoma maligno, dois Schwannomas benignos e um fibrolipoma neural) e um como hanseníase tuberculoide.
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Humanos , Masculino , Feminino , Adolescente , Adulto , Pessoa de Meia-Idade , Neoplasias do Sistema Nervoso Periférico/diagnóstico , Hanseníase Tuberculoide/diagnóstico , Neurilemoma , Diagnóstico DiferencialRESUMO
OBJECTIVES: To investigate if neurodynamic treatment is more effective than advice to remain active in patients with nerve-related leg pain. DESIGN: Parallel-group randomized controlled trial blinded to the outcome assessor conducted in Porto Alegre, Brazil. PARTICIPANTS: Sixty patients recruited from the community and private practices. INTERVENTION: Patients will be randomly assigned to receive four sessions of neurodynamic treatment over two weeks comprising passive lumbar foramen opening and neurodynamic sliders plus home exercises or advice to remain active. MAIN OUTCOME MEASURES: Leg pain intensity, disability, low back pain intensity, functional ability, symptoms distribution and global impression of recovery will be assessed at two and four weeks after randomization. ANALYSIS: A linear mixed model will be employed for each outcome following intention to treat principles.
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Dor Lombar/reabilitação , Modalidades de Fisioterapia , Ciática/reabilitação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil , Avaliação da Deficiência , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor , Amplitude de Movimento Articular , Projetos de Pesquisa , Método Simples-Cego , Adulto JovemRESUMO
ABSTRACTIntroduction:Many nervous system tissues and cells suffers positive changes when faced to exercise training. However, data on vagus nerve adaptation from exercise-induced study is absent.Objective:To analyze the effect of an endurance training on the vagus nerve morphology of rats.Methods:Wistar rats (6 months of age) were divided into two groups: control group (CG, n=8), and aerobic trained group (AT, n=8). AT was submitted to a treadmill training program of five times per week during 12 weeks. The maximum speed stipulated in the training protocol corresponded to 60% of the mean maximum intensity achieved by the group in the test of maximum effort.Results:Twelve weeks of treadmill training resulted in left ventricular hypertrophy in the AT group com-pared to CG. There was a significant increase in the area of both the myelinated and unmyelinated axons, and in the area of myelin sheath with training. The number of neurotubules and neurofilaments in myelinated fibers of aerobic trained group was significantly greater than CG (p≤0.05).Conclusion:Endurance training promoted significant increase in morphometric parameters of the vagus nerve in the same way it affect somatic nerves.
RESUMOIntrodução:Muitos tecidos e células do sistema nervoso sofrem alterações positivas quando se defrontam com o treinamento físico. Entretanto, dados sobre a adaptação do nervo vago decorrente de estudos com exercício físico são ausentes.Objetivo:Analisar o efeito do treinamento de endurance sobre a morfologia do nervo vago de ratos.Métodos:Ratos Wistar (6 meses de idade) foram divididos em dois grupos: grupo controle (GC, n=8), e grupo com treinamento aeróbico (TA, n=8). O grupo TA foi submetido a um programa de treinamento em esteira rolante, cinco vezes por semana durante 12 semanas. A velocidade máxima estipulada no protocolo de treinamento correspondeu a 60% da intensidade média alcançada pelo grupo no teste de esforço máximo.Resultados:Doze semanas de treinamento em esteira rolante resultou em hipertrofia ventricular no grupo TA em comparação ao GC. Foi verificado um aumento significativo na área de ambos axônios mielinizados e não mielinizados, e na área da bainha de mielina com treinamento. O número de neurotúbulos e neurofilamentos das fibras mielinizadas foi significativamente maior no grupo com treinamento aeróbico em comparação ao GC (p≤0,05).Conclusão:O treinamento de endurance promoveu aumento significativo nos parâmetros morfométricos do nervo vago da mesma forma que isto afeta os nervos somáticos.
RESUMENIntroducción:Muchos tejidos del sistema nervioso y células sufren cambios positivos cuando se enfrentan con el entrenamiento físico. Sin embargo, los datos sobre la adaptación del nervio vago que resulta de los estudios con el ejercicio son ausentes.Objetivo:Analizar el efecto del entrenamiento de endurance en la morfología del nervio vago de ratones.Método:Ratones Wistar (6 meses de edad) se dividieron en dos grupos: grupo control (GC, n= 8) y grupo con entrenamiento aeróbico (TA, n=8). El grupo TA se sometió a un programa de entrenamiento sobre una cinta de correr cinco veces por semana durante 12 semanas. La velocidad máxima estipulada en el protocolo de entrenamiento correspondió al 60% de la intensidad media máxima alcanzada por el grupo en la prueba de ejercicio máximo.Resultados:Doce semanas de entrenamiento en una cinta resultaron en la hipertrofia ventricular en el grupo TA en comparación con GC. Se obtuvo un aumento significativo en el área de ambos axones mielinizados y no mielinizados, y en el área de la vaina de mielina con entrenamiento. El número de neurotúbulos y neurofilamen-tos de fibras mielinizadas fue significativamente mayor en el grupo con entrenamiento aeróbico en comparación con GC (p = 0,05).Conclusión:El entrenamiento de endurance causó un aumento significativo en los parámetros morfométricos del nervio vago en la misma forma en que afecta a los nervios somáticos.
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Through a wide range of cellular and molecular events, the peripheral nervous system is endowed with great regenerative capacity, responding immediately to injuries that occur along the length of the nerve. The aim of this study was to histomorphometrically assess the degree of maturity of the nervous tissue and possible microscopic changes in newly formed nerve segments 60 days after experimental neurotmesis of the sciatic nerve in rats. Control Group (CG) and an Injury Group (IG) were used. IG underwent neurotmesis of the sciatic nerve of the right foot, with immediate surgical repair using the tubulization technique. 60 days following experimental surgery, animals from both groups had their sciatic nerves collected for histomorphometric analysis. Statistical analysis was performed, using the Student t-test for independent samples, expressed as mean ± standard deviation, with 5% significance. In the event of injury, peripheral nerve tissue is mobilized in an intrinsic self-healing process. 60 days following of nerve regeneration in neurotmesis injury, the peripheral nerve presents a segment joining the newly formed neural stump. The new stump has a number of regenerated axons compatible with an intact nerve, but which still show great immaturity in the axonal structural layers of the nerve.
Mediante diversos procesos celulares y moleculares, el sistema nervioso periférico tiene una gran capacidad regenerativa, respondiendo inmediatamente a las lesiones ocurridas a lo largo de su extensión. El objetivo de este estudio fue evaluar histomorfométricamente el grado de madurez del tejido nervioso y los posibles cambios microscópicos en los segmentos nerviosos recién formados 60 días después de la neurotmesis experimental en el nervio ciático de ratas. Se utilizaron 9 ratas (Wistar) separadas en grupo control (GC, n= 4) y Grupo lesión (GL, n= 5). A los 60 días de vida, el grupo GL fue sometido a neurotmesis del nervio ciático de la miembro posterior derecho, con inmediata corección quirúrgica con la técnica de tubolización. Completados 60 días luego de la cirugía experimental, los animales de ambos grupos fueron anestesiados y sus nervios ciáticos seccionados para el análisis histomorfométrico. Se realizó un análisis estadístico utilizando la prueba t de Student para muestras independientes, expresado como media ± desviación estándar, con un 5% de significancia. A los 60 días de la lesión por neurotmesis, el nervio ciático del GL presentó alteraciones histomorfométricas significativas para las variables: número de vasa nevorum, densidad de fibras mielínicas, diámetro axonal y de fibras mielínicas, espesor de la vaina de mielina y razón G, con similitud solamente para los números absolutos de fibras mielínicas regeneradas. El nervio periférico durante su proceso regenerativo, pasa por grandes alteraciones estructurales, siguiendo una secuencia coordinada de acciones, que dependiendo de las condiciones del microambiente donde ocurre esta regeneración, podrá ser clave para el nivel de regenerecion nerviosa periférica.
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Animais , Masculino , Ratos , Regeneração Nervosa , Nervo Isquiático/patologia , Traumatismos do Sistema Nervoso/patologia , Ratos WistarRESUMO
Introduction Schwannoma of the olfactory groove is an extremely rare tumor that can share a differential diagnosis with meningioma or neuroblastoma. Objectives The authors present a case of giant schwannoma involving the anterior cranial fossa and ethmoid sinuses. Case Report The patient presented with a 30-month history of left nasal obstruction, anosmia, and sporadic ipsilateral bleeding. Computed tomography of the paranasal sinuses revealed expansive lesion on the left nasal cavity extending to nasopharynx up to ethmoid and sphenoid sinuses bilaterally with intraorbital and parasellar extension to the skull base. Magnetic resonance imaging scan confirmed the expansive tumor without dural penetration. Biopsy revealed no evidence of malignancy and probable neural cell. Bifrontal craniotomy was performed combined with lateral rhinotomy (Weber-Ferguson approach), and the lesion was totally removed. The tumor measured 8.0 × 4.3 × 3.7 cm and microscopically appeared as a schwannoma composed of interwoven bundles of elongated cells (Antoni A regions) mixed with less cellular regions (Antoni B). Immunohistochemical study stained intensively for vimentin and S-100. Conclusion Schwannomas of the olfactory groove are extremely rare, and the findings of origin of this tumor is still uncertain but recent studies point most probably to the meningeal branches of trigeminal nerve or anterior ethmoidal nerves.
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Introduction Schwannoma of the olfactory groove is an extremely rare tumor that can share a differential diagnosis with meningioma or neuroblastoma. Objectives The authors present a case of giant schwannoma involving the anterior cranial fossa and ethmoid sinuses. Case Report The patient presented with a 30-month history of left nasal obstruction, anosmia, and sporadic ipsilateral bleeding. Computed tomography of the paranasal sinuses revealed expansive lesion on the left nasal cavity extending to nasopharynx up to ethmoid and sphenoid sinuses bilaterally with intraorbital and parasellar extension to the skull base. Magnetic resonance imaging scan confirmed the expansive tumor without dural penetration. Biopsy revealed no evidence of malignancy and probable neural cell. Bifrontal craniotomy was performed combined with lateral rhinotomy (Weber-Ferguson approach), and the lesion was totally removed. The tumor measured 8.0 4.3 3.7 cm and microscopically appeared as a schwannoma composed of interwoven bundles of elongated cells (Antoni A regions)mixed with less cellular regions (Antoni B). Immunohistochemical study stained intensively for vimentin and S-100. Conclusion Schwannomas of the olfactory groove are extremely rare, and the findings of origin of this tumor is still uncertain but recent studies point most probably to the meningeal branches of trigeminal nerve or anterior ethmoidal nerves. .
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Animais , Feminino , Masculino , Camundongos , Permeabilidade da Membrana Celular/fisiologia , Células Ciliadas Auditivas/fisiologia , Canais Iônicos/fisiologia , Mecanotransdução Celular/fisiologia , Animais Recém-Nascidos , Caderinas/genética , Permeabilidade da Membrana Celular/genética , Quelantes/farmacologia , Sulfato de Di-Hidroestreptomicina/farmacologia , Embrião de Mamíferos , Ácido Egtázico/análogos & derivados , Ácido Egtázico/farmacologia , Células Ciliadas Auditivas/citologia , Células Ciliadas Auditivas/efeitos dos fármacos , Técnicas In Vitro , Canais Iônicos/efeitos dos fármacos , Camundongos Transgênicos , Mecanotransdução Celular/efeitos dos fármacos , Mecanotransdução Celular/genética , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/genética , Miosinas/genética , Órgão Espiral/citologia , Precursores de Proteínas/genéticaRESUMO
La neuroplasticidad es la potencialidad del sistema nervioso de modificarse para formar conexiones nerviosas en respuesta a la información nueva, la estimulación sensorial, el desarrollo, la disfunción o el daño. En general, la neuroplasticidad suele asociarse al aprendizaje que tiene lugar en la infancia, pero sus definiciones van más allá y tienen un recorrido histórico. Hay diversos componentes bioquímicos y fisiológicos detrás de un proceso de neuroplasticidad y esto lleva a diferentes reacciones biomoleculares químicas, genómicas y proteómicas que requieren de acciones intra y extra neuronales para generar una respuesta neuronal.
Neuroplasticity is the potentiality of the nervous system to change itself and to form neural connections in response to a new information, sensorial stimulation, development, dysfunction or damage. In general, neuroplasticity is often associated with learning during the childhood, but their definitions its going further, and it has an historical follow-up. There are many biochemical and physiological components behind neuroplasticity process, and this leads to biomolecular, chemical, genomics and proteomics processes, that requiring intra and extra-neuronal actions to generate a neural response.
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INTRODUÇÃO: O potencial de ação (PA) origina-se graças a uma perturbação do estado de repouso da membrana celular, com consequente fluxo de íons, por meio da membrana e alteração da concentração iônica nos meios intra e extracelular. OBJETIVOS: Sintetizar o conhecimento científico acumulado até o presente sobre o potencial de ação neural e o seu processo de adaptação sob aplicação de um estímulo constante. MATERIAIS E MÉTODOS: Busca realizada nas bases Springer, ScienceDirect, PubMed, IEEE Xplore, Google Acadêmico, Portal de Periódicos da Capes, além de livros referentes ao assunto. O idioma de preferência selecionado foi o inglês, com as keywords: action potential; adaptation; accommodation; rheobase; chronaxy; nerve impulse. Efetuou-se a procura de artigos com uma janela de tempo de 1931 a 2010 e livros de 1791 a 2007. RESULTADOS: Dos trabalhos selecionados, foram extraídas informações a respeito dos seguintes tópicos: potencial de ação e suas fases; condução nervosa; reobase; cronaxia; acomodação; e adaptação neuronal. CONCLUSÃO: Um estímulo que crie PA, se aplicado de maneira constante, pode reduzir a frequência de despolarizações em função do tempo e, consequentemente, adaptar a célula. O tempo que a célula demora, na ausência de estímulos, para recuperar sua frequência original é definido como desadaptação.
INTRODUCTION: The action potential (AP) arises due to a disturbance of the resting state of the cell membrane with consequent flow of ions across the membrane and ion concentration changes in intra and extra cellular space. OBJECTIVES: This article aims to summarize the scientific knowledge accumulated to date on the action potential and neural adaptation in the process of applying a constant stimulus. MATERIALS AND METHODS: This is a literature review on the bases Springer, ScienceDirect, PubMed, IEEE Xplore, Google Scholar, Capes Periodicals Portal as well as books on the topic. The selected preferred language was English with the keywords: action potential; adaptation, accommodation; rheobase; chronaxy; nerve impulse. We conducted a search of articles with a wide time window from 1931 to 2010 and books from 1791 to 2007. RESULTS: In the selected studies was extracted information about the following topics: action potential and its stages; nerve conduction; rheobase; chronaxie, accommodation, and adaptation. CONCLUSION: A stimulus that creates AP, if applied consistently, can reduce the frequency of depolarization as a function of time and, consequently, to adapt the cell. The time it takes the cell in the absence of stimuli, to recover its original frequency, is defined as a disadaptation.
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Potenciais de Ação , Adaptação Fisiológica , Cronaxia , Canais Iônicos , Tecido NervosoRESUMO
Neurofibroma é uma proliferação hamartomatosa de origem neuromesenquimal. Pode ser encontrado associado à neurofibromatose ou como tumor solitário, sendo sua apresentação subungueal solitária bastante rara. É mais frequente em pacientes do sexo feminino e a cirurgia é o tratamento de escolha. Relatase um caso de um paciente masculino, com lesão tumoral subungueal no pododáctilo, cuja biópsia e imuno-histoquímica foram compatíveis com neurofibroma. Até a presente data, menos de dez casos sobre neurofibromas subungueais sem associação com doença de Von Recklinhausen foram documentados, sendo este o primeiro caso relatado no Brasil e o único no sexo masculino no mundo.
A neurofibroma is a hamartomatous proliferation of neuromesenchymal origin. It may be found in combination with neurofibromatosis or in the form of a solitary tumor. Clinical presentation as a solitary subungual tumor is very rare. Neurofibroma is more common in females and surgery is the treatment of choice. The present paper reports the case of a male patient with a subungual tumor on his toe. Biopsy and immunohistochemistry findings were compatible with a neurofibroma. To date, fewer than ten cases of subungual neurofibromas unassociated with von Recklinghausen's disease have been documented, this being the first case to be reported in Brazil and the only report worldwide to have described this condition in a male patient.