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BACKGROUND: Many studies have emphasized the importance of interface contact between implants and the vertebral endplate (VE). The goal of this study was to analyze the shape and other specific parameters of the VE to provide reference data for better implant interface contact in intervertebral disc space procedures. METHODS: Cervical, thoracic, and lumbar spine midsagittal plane magnetic resonance images of 100 adults (58 women) were analyzed. The morphology of the VEs was classified as concave, convex, flat, or irregular. Midsagittal endplate length (ML), endplate concavity depth (ECD), and endplate concavity axis (ECA) location were measured in the midsagittal plane. The parameters were compared between the cervical, thoracic, and lumbar spines and between the sexes. RESULTS: The VE morphology, ML, ECD, and ECA showed variations along the spine, mainly in the cervical and lower lumbar spines. The sagittal geometry of the VE was not flat or uniform along the cervical, thoracic, and lumbar spines. Different morphological types were observed along different spinal segments and according to sex. In the cervical spine, the majority of cranial VEs were flat, while caudal VEs were mostly concave. CONCLUSION: Sagittal VE geometry should be taken into consideration during the use of intervertebral cages or disc arthroplasty.
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Myasthenia gravis is a rare and invalidating disease affecting the neuromuscular junction of voluntary muscles. The classical form of this autoimmune disease is characterized by the presence of antibodies against the most abundant protein in the neuromuscular junction, the nicotinic acetylcholine receptor. Other variants of the disease involve autoimmune attack of non-receptor scaffolding proteins or enzymes essential for building or maintaining the integrity of this peripheral synapse. This review summarizes the participation of the above proteins in building the neuromuscular junction and the destruction of this cholinergic synapse by autoimmune aggression in myasthenia gravis. The review also covers the application of a powerful biophysical technique, superresolution optical microscopy, to image the nicotinic receptor in live cells and follow its motional dynamics. The hypothesis is entertained that anomalous nanocluster formation by antibody crosslinking may lead to accelerated endocytic internalization and elevated turnover of the receptor, as observed in myasthenia gravis.
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Joint immobilization is commonly used as a conservative treatment for osteoarticular and musculotendinous traumas. However, joint immobilization might elicit degenerative effects on the neuromuscular system and muscle atrophy. For this reason, the choice of strategies that mitigate these effects is essential in the post-immobilization period. Therefore, this study aimed to investigate the impact of aquatic training on the morphology of muscle fibers and motor endplates of the gastrocnemius muscle in the post-immobilization period. Male Wistar rats (90 days old) were divided into groups: Sedentary: no procedure; Immobilization: joint immobilization protocol (10 days); Immobilization/non-training: joint immobilization protocol (10 days) followed by four weeks without exercise intervention; Immobilization/training: joint immobilization protocol (10 days) and post-immobilization aquatic training (4 weeks). After the procedures, we quantified the cross-sectional area (CSA), volume and numerical density of different myofibers types, and total and stained area and perimeter of the motor endplate. We demonstrate the following main results: (a) short-term joint immobilization resulted in myofibers atrophy; however, we verified a small change in the postsynaptic component; (b) the period of inactivity after immobilization caused severe changes in the motor endplate (lower stained area, stained perimeter, total area, and total perimeter) and maintenance of muscle atrophy due to immobilization; (c) the prescription of post-immobilization exercise proved to be effective in restoring muscle morphology and inducing plasticity in the motor endplate. We conclude that short-term joint immobilization (10 days) results in atrophy type I and II myofibers, in addition to a decline in the total perimeter of the motor endplate. Besides, the post-immobilization period appears to be decisive in muscle and postsynaptic remodeling. Thus, aquatic training is effective in stimulating adjustments associated with muscle hypertrophy and plasticity of the motor endplate during the post-immobilization period.
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Terapia por Exercício , Placa Motora/metabolismo , Músculo Esquelético/metabolismo , Junção Neuromuscular/metabolismo , Animais , Masculino , Ratos , Ratos WistarRESUMO
ABSTRACT Objective To evaluate whether vertebral endplate signal changes (VESCs) influence the prognosis of patients submitted to conservative or surgical treatment for low back pain and lumbosciatica. Methods Study with 241 patients who underwent conservative treatment, infiltration or surgery with 12 months of follow-up. They were evaluated for pain by the Visual Analog Scale for Pain (VAS), for function by the Roland Morris questionnaire and for quality of life by the EuroQoI5 (EQ-5D). Results The VESCs did not have a significant effect on the treatment responses for the VAS (F = 0.03; P = 0.97), Roland Morris (F = 0.51; P = 0.60) and EQ-5D (F = 2.67; P = 0.07) variables, nor was there any interaction between VESC and treatment for VAS (F = 2.15; P = 0.08), Roland Morris (F = 1.55; P = 0.19) and EQ-5D (F = 2.15; P = 0.08). There was a significant effect for all treatments, however, the effect of the surgical procedure was superior when compared to the others (P <0.001). The VESC frequency was 48.33% for type 0, 29.17% for type I and 22.50% for type II. Conclusions The presence of VESC and its different types is not associated with a worse prognosis, nor was a higher prevalence of VESC observed in the patients with low back pain and lumbosciatica. Level of Evidence II; Retrospective cohort study.
RESUMO Objetivo Avaliar se as alterações de sinal do platô vertebral (ASPV) influenciam o prognóstico de pacientes submetidos ao tratamento conservador ou cirúrgico em lombalgia e lombociatalgia. Métodos Estudo com 241 pacientes submetidos ao tratamento conservador, infiltração ou cirurgia, com acompanhamento de 12 meses. Foram avaliados pela Escala Visual Analógica (EVA) da Dor, quanto à função, pelo questionário Roland Morris e quanto à qualidade de vida, pelo questionário EuroQoI5 (EQ-5D). Resultados As ASPV não tiveram efeito significante nas respostas do tratamento para as variáveis EVA (F = 0,03; P = 0,97), Roland Morris (F = 0,51; P = 0,60) e EQ-5D (F = 2,67; P = 0,07), bem como não houve interação de ASPV e tratamento para EVA (F = 2,15; P = 0,08), Roland Morris (F = 1,55; P = 0,19) e EQ-5D (F = 2,15; P = 0,08). Houve efeito significante para todos os tratamentos; entretanto, o efeito do procedimento cirúrgico foi superior quando comparado aos demais (P < 0,001). A frequência de ASPV tipo 0 foi 48,33%, tipo I foi 29,17% e tipo II foi 22,50%. Conclusões A presença de ASPV e seus diferentes tipos não estão associados a prognóstico pior, bem como não se demonstrou maior prevalência de ASPV nos pacientes com lombalgia e lombociatalgia. Nível de Evidência II; Estudo de coorte retrospectivo.
RESUMEN Objetivo Evaluar si las alteraciones de señal de la meseta vertebral (ASMV) influyen en el pronóstico de los pacientes sometidos a tratamiento conservador o quirúrgico en lumbalgia y lumbociatalgia. Métodos Estudio con 241 pacientes sometidos al tratamiento conservador, infiltración o cirugía, con acompañamiento de 12 meses. Se evaluaron a través de la Escala Visual Analógica del Dolor (EVA), cuanto a la función, por el cuestionario Roland Morris y cuanto a la calidad de vida por el cuestionario EuroQoI5 (EQ-5D). Resultados Las ASMV no tuvieron efecto significativo en las respuestas del tratamiento para las variables EVA (F = 0,03; P = 0,97), Roland Morris (F = 0,51; P = 0,60) y EQ-5D (F = 2,67; P = 0,07), así como no hubo interacción de ASMV y tratamiento para EVA (F = 2,15; P = 0,08), Roland Morris (F = 1,55; P = 0,19) y EQ-5D (F = 2,15; P = 0,08). Hubo efecto significativo para todos los procedimientos, entretanto, el efecto del procedimiento quirúrgico fue superior cuando comparado a los demás (P <0,001). La frecuencia de ASMV para el tipo 0 fue 48,33%, tipo I 29,17% y tipo II 22,50%. Conclusiones La presencia de ASMV y sus diferentes tipos no están asociados a pronóstico peor, bien como no se demostró mayor prevalencia de ASMV en los pacientes con lumbalgia y lumbociatalgia. Nivel de Evidencia II; Estudio de cohorte retrospectivo.
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Humanos , Dor Lombar , Ciática , Cirurgia Geral , Tratamento ConservadorRESUMO
INTRODUCTION: Upper limb movements are affected frequently by brain ischemia (BI). Mechanisms involved in recovery and compensatory movements have developed several studies. However, less attention is given to skeletal muscles, where neuromuscular junction (NMJ) has an important role on muscle tropism and functional performance. METHODS: Animals were divided into two groups: control (C) and BI. Then, animals were skilled to perform single-pellet retrieval task, following these procedures: habituation, shaping, and single-pellet retrieval task. BI was induced using stereotaxic surgery in order to apply endothelin-1 in motor cortex, representative of movements of dominant paw. Reaching task performance was evaluated by single-pellet retrieval task 1 day before BI induction, 4 and 15 days after BI induction. After that, biceps, triceps, fingers flexor, and extensor muscles were extracted. NMJ was assessed in morphometric characteristics (total area, total perimeter, and feret). Muscle fiber cross-sectional area and connective tissue percentage were also evaluated for characterization. Student's t test was used for comparisons between C and BI groups. Tau Kendall's correlation was applied among variables from BI group. RESULTS: An increase in all NMJ morphometric parameters, as well as increase of atrophy and fibrosis in BI group compared with C. There was a high level of direct correlation between mean values of NMJ morphometry with percentage of success in reaching task in BI group. CONCLUSION: Brain ischemia-induced NMJ compensatory expansion, muscle atrophy, and fibrosis in forelimb muscles that are related to reaching performance.
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Adaptação Fisiológica/fisiologia , Isquemia Encefálica/fisiopatologia , Córtex Cerebral/fisiopatologia , Membro Anterior/fisiopatologia , Atividade Motora/fisiologia , Junção Neuromuscular/fisiopatologia , Recuperação de Função Fisiológica/fisiologia , Animais , Masculino , Movimento/fisiologia , Desempenho Psicomotor/fisiologia , RatosRESUMO
Upper limb performance is affected by diabetes mellitus (DM). Neuromuscular junction (NMJ) is a key structure to understand the relationship between performance and morphology in DM. The aim of the study was to analyze NMJ plasticity due to DM in an animal model and its relationship with the function of forelimbs in rats. Twelve Wistar rats were divided into control (C) and DM groups. Animals were trained to perform a grasping task, following procedures of habituation, shaping, and reaching task. DM was induced using streptozotocin. Forelimb neuromuscular performance for dexterity was evaluated one day before DM induction and five weeks following induction. After that, biceps, triceps, and finger flexors and extensors were removed. Connective tissue and muscle fiber cross-sectional area (CSA) were measured. NMJ was assessed by its morphometric characteristics (area, perimeter, and maximum diameter), using ImageJ software. Motor performance analyses were made using single pellet retrieval task performance test. Student's t-test was used for comparisons between groups. A significant decrease in all NMJ morphometric parameters was observed in the DM group compared with the C group. Results showed that DM generated NMJ retraction in muscles involved in a reaching task. These alterations are related to signs of muscular atrophy and to poor reaching task performance. In conclusion, induced DM caused NMJ retraction and muscular atrophy in muscles involved in reaching task performance. Induced DM caused significantly lower motor performance, especially in the final moments of evaluation, when DM compromised the tropism of the muscular tissue.
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Animais , Masculino , Coelhos , Ratos , Análise e Desempenho de Tarefas , Adaptação Fisiológica/fisiologia , Diabetes Mellitus Experimental/patologia , Junção Neuromuscular/patologia , Ratos Wistar , Diabetes Mellitus Experimental/fisiopatologia , Junção Neuromuscular/fisiopatologiaRESUMO
Acetazolamide (AZ), a molecule frequently used to treat different neurological syndromes, is an inhibitor of the carbonic anhydrase (CA), an enzyme that regulates pH inside and outside cells. We combined fluorescent FM styryl dyes and electrophysiological techniques at ex vivo levator auris longus neuromuscular junctions (NMJs) from mice to investigate the modulation of synaptic transmission and vesicle recycling by AZ. Transmitter release was minimally affected by AZ, as evidenced by evoked and spontaneous end-plate potential measurements. However, optical evaluation with FM-styryl dyes of vesicle exocytosis elicited by 50 Hz stimuli showed a strong reduction in fluorescence loss in AZ treated NMJ, an effect that was abolished by bathing the NMJ in Hepes. The remaining dye was quenched by bromophenol, a small molecule capable of diffusing inside vesicles. Furthermore, in transgenic mice expressing Synaptophysin-pHluorin (SypHy), the fluorescence responses of motor nerve terminals to a 50 Hz train of stimuli was decrease to a 50% of controls in the presence of AZ. Immunohistochemistry experiments to evaluate the state of the Myosin light chain kinase (MLCK), an enzyme involved in vesicle recycling, demonstrated that MLCK phosphorylation was much stronger in the presence than AZ than in its absence in 50 Hz stimulated NMJs. We postulate that AZ, via cytosol acidification and activation of MLCK, shifts synaptic vesicle recycling to a fast (kiss-and-run) mode, which changes synaptic performance. These changes may contribute to the therapeutic action reported in many neurological syndromes like ataxia, epilepsy, and migraine.
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Acetazolamida/farmacologia , Inibidores da Anidrase Carbônica/farmacologia , Fármacos Neuromusculares/farmacologia , Junção Neuromuscular/efeitos dos fármacos , Vesículas Sinápticas/efeitos dos fármacos , Animais , Miosinas Cardíacas/metabolismo , Citosol/efeitos dos fármacos , Citosol/metabolismo , Exocitose/efeitos dos fármacos , Exocitose/fisiologia , Concentração de Íons de Hidrogênio , Masculino , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Cadeias Leves de Miosina/metabolismo , Quinase de Cadeia Leve de Miosina/metabolismo , Junção Neuromuscular/citologia , Junção Neuromuscular/metabolismo , Fosforilação/efeitos dos fármacos , Vesículas Sinápticas/metabolismoRESUMO
BACKGROUND: The innervation zone (IZ) corresponds to the location of the neuromuscular junctions. Its location can be determined by using arranged surface linear electrode arrays. Typically, voluntary muscle contractions (VC) are used in this method. However, it also may be necessary to locate the IZ under clinical conditions such as spasticity, in which this type of contraction is difficult to perform. Therefore, contractions imposed by electrostimulation (ES) can be an alternative. There is little background comparing the locations of IZ obtained by two different types of contractions. OBJECTIVE: Evaluate the concordance between using voluntary and imposed contractions from electrostimulation in order to determine the location of the innervation zone of the tibialis anterior muscle in healthy volunteers. METHODS: The tibialis anterior (TA) muscle of sixteen volunteers (men: 8; women: 8; age: 22.1±1.4years, weight: 61.6±7.5kg, height: 167.1±7.5cm) were evaluated using a linear electrode array. The IZ of the TA muscle was located using two types of muscle contractions, voluntary (10% MVC) and imposed contractions by ES. The concordance between both conditions was evaluated using the Bland-Altman method and the concordance correlation coefficient (CCC). The analyses were applied to the absolute and relative positions to the length of an anatomical landmark frame. RESULTS: CCC for absolute position was 0.98 (p<0.0001, 95% CI [0.98-1.00], and CCC for relative positions also was 0.98 (p<0.0001, 95% CI [0.97-1.00]). The Bland-Altman analysis for absolute data showed an average difference of -0.63mm (SD: 4.1). Whereas, for adjusted data, the average difference was -0.20% (SD: 1.2). The power of the results, based on absolute data, was 98%, whereas for relative data, 82%. CONCLUSION: In healthy volunteers, there was a substantially concordance between the location of the IZ of the TA muscle derived from using contractions imposed by ES and the location derived from using VC.
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Eletromiografia/métodos , Contração Muscular/fisiologia , Músculo Esquelético/inervação , Músculo Esquelético/fisiologia , Junção Neuromuscular/fisiologia , Adulto , Estimulação Elétrica/métodos , Eletrodos , Feminino , Humanos , Masculino , Adulto JovemRESUMO
Recently, we demonstrated the existence of nonextensive behavior in neuromuscular transmission (da Silva et al. in Phys Rev E 84:041925, 2011). In this letter, we first obtain a maximum-likelihood q-estimator to calculate the scale factor ([Formula: see text]) and the q-index of q-Gaussian distributions. Next, we use the indexes to analyze spontaneous miniature end plate potentials in electrophysiological recordings from neuromuscular junctions. These calculations were performed assuming both normal and high extracellular potassium concentrations [Formula: see text]. This protocol was used to test the validity of Tsallis statistics under electrophysiological conditions closely resembling physiological stimuli. The analysis shows that q-indexes are distinct depending on the extracellular potassium concentration. Our letter provides a general way to obtain the best estimate of parameters from a q-Gaussian distribution function. It also expands the validity of Tsallis statistics in realistic physiological stimulus conditions. In addition, we discuss the physical and physiological implications of these findings.
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Potenciais Pós-Sinápticos em Miniatura/fisiologia , Junção Neuromuscular/fisiologia , Potássio/fisiologia , Animais , Diafragma/inervação , Diafragma/fisiologia , Funções Verossimilhança , Camundongos , Distribuição Normal , Transmissão Sináptica/fisiologiaRESUMO
BACKGROUND: Botulinum toxin (BTX) acts on the neuromuscular junction which can be located by the innervation zone (IZ). Clinically, the motor point (MP) is homologous to the IZ and it is used as the injection site of BTX. Differences in the effectiveness of the application of BTX between MP and IZ locations have been determined. OBJECTIVE: Compare the location of the MP obtained using electrical stimulation and the location of the IZ using a linear surface electrodes array on the biceps brachii muscle. METHODS: The biceps brachii muscle of twenty men was assessed. The MP was located using the torque measurement generated by electrical stimulation. The IZ was detected using a linear surface electrodes array. RESULTS: A difference between the MP and the IZ positions (75.8 vs. 86.5mm, delta 10.7 mm; p=0.003, post-hoc power 0.89) was observed. DISCUSSION: The magnitude of the difference between the MP and the IZ may be clinically relevant. The IZ location using surface electromyography as a guide to optimize BTX injection is proposed.
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Toxinas Botulínicas/administração & dosagem , Espasticidade Muscular/diagnóstico , Espasticidade Muscular/tratamento farmacológico , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/inervação , Junção Neuromuscular/efeitos dos fármacos , Estudos Transversais , Cotovelo/inervação , Cotovelo/fisiologia , Eletromiografia/métodos , Humanos , Masculino , Músculo Esquelético/fisiologia , Junção Neuromuscular/fisiologia , Adulto JovemRESUMO
Current studies find that degenerated cartilage endplates (CEP) of vertebrae, with fewer diffusion areas, decrease nutrient supply and accelerate intervertebral disc degeneration. Many more apoptotic cells have been identified in degenerated than in normal endplates, and may be responsible for the degenerated grade. Previous findings suggest that inhibition of apoptosis is one possible approach to improve disc regeneration. It is postulated that inhibition of CEP cell apoptosis may be responsible for the regeneration of endplates. Caspase-3, involved in the execution phase of apoptosis, is a candidate for regulating the apoptotic process. In the present study, CEP cells were incubated in 1% fetal bovine serum. Activated caspases were detected to identify the apoptotic pathway, and apoptosis was quantified by flow cytometry. Lentiviral caspase-3 short hairpin RNA (shRNA) was employed to study its protective effects against serum deprivation. Silencing of caspase-3 expression was quantified by reverse transcription-polymerase chain reaction and Western blots, and inhibition of apoptosis was quantified by flow cytometry. Serum deprivation increased apoptosis of rat CEP cells through activation of a caspase cascade. Lentiviral caspase-3 shRNA was successfully transduced into CEP cells, and specifically silenced endogenous caspase-3 expression. Surviving cells were protected by the downregulation of caspase-3 expression and activation. Thus, lentiviral caspase-3 shRNA-mediated RNAi successfully silenced endogenous caspase-3 expression, preventing inappropriate or premature apoptosis.