Safe Needle Insertion Locations for Motor Point Injection of the Triceps Brachii Muscle: A Pilot Cadaveric and Ultrasonography Study

OBJECTIVE: To determine the location of the motor endplate zones (MoEPs) for the three heads of the triceps brachii muscles during cadaveric dissection and estimate the safe injection zone using ultrasonography.METHODS: We studied 12 upper limbs of 6 fresh cadavers obtained from body donations to the medical school anatomy institution in Seoul, Korea. The locations of MoEPs were expressed as the percentage ratio of the vertical distance from the posterior acromion angle to the midpoint of the olecranon process. By using the same reference line as that used for cadaveric dissection, the safe injection zone away from the neurovascular bundle was identified in 6 healthy volunteers via ultrasonography. We identified the neurovascular bundle and its location with respect to the distal end of the humerus and measured its depth from the skin surface.RESULTS: The MoEPs for the long, lateral, and medial heads were located at a median of 43.8%, 54.8%, and 60.4% of the length of the reference line in cadaver dissection. The safe injection zone of the medial head MoEPs corresponded to a depth of approximately 3.5 cm from the skin surface and 1.4 cm away from the humerus, as determined by sonography.CONCLUSION: Correct identification of the motor points for each head of the triceps brachii would increase the precision and efficacy of motor point injections to manage elbow extensor spasticity.

Inhibition of KLF7-Targeting MicroRNA 146b Promotes Sciatic Nerve Regeneration / 神经科学通报·英文版

A previous study has indicated that Krüppel-like factor 7 (KLF7), a transcription factor that stimulates Schwann cell (SC) proliferation and axonal regeneration after peripheral nerve injury, is a promising therapeutic transcription factor in nerve injury. We aimed to identify whether inhibition of microRNA-146b (miR-146b) affected SC proliferation, migration, and myelinated axon regeneration following sciatic nerve injury by regulating its direct target KLF7. SCs were transfected with miRNA lentivirus, miRNA inhibitor lentivirus, or KLF7 siRNA lentivirus in vitro. The expression of miR146b and KLF7, as well as SC proliferation and migration, were subsequently evaluated. In vivo, an acellular nerve allograft (ANA) followed by injection of GFP control vector or a lentiviral vector encoding an miR-146b inhibitor was used to assess the repair potential in a model of sciatic nerve gap. miR-146b directly targeted KLF7 by binding to the 3'-UTR, suppressing KLF7. Up-regulation of miR-146b and KLF7 knockdown significantly reduced the proliferation and migration of SCs, whereas silencing miR-146b resulted in increased proliferation and migration. KLF7 protein was localized in SCs in which miR-146b was expressed in vivo. Similarly, 4 weeks after the ANA, anti-miR-146b increased KLF7 and its target gene nerve growth factor cascade, promoting axonal outgrowth. Closer analysis revealed improved nerve conduction and sciatic function index score, and enhanced expression of neurofilaments, P0 (anti-peripheral myelin), and myelinated axon regeneration. Our findings provide new insight into the regulation of KLF7 by miR-146b during peripheral nerve regeneration and suggest a potential therapeutic strategy for peripheral nerve injury.

The Scaffolding Protein, Grb2-associated Binder-1, in Skeletal Muscles and Terminal Schwann Cells Regulates Postnatal Neuromuscular Synapse Maturation

The vertebrate neuromuscular junction (NMJ) is considered as a “tripartite synapse” consisting of a motor axon terminal, a muscle endplate, and terminal Schwann cells that envelope the motor axon terminal. The neuregulin 1 (NRG1)-ErbB2 signaling pathway plays an important role in the development of the NMJ. We previously showed that Grb2-associated binder 1 (Gab1), a scaffolding mediator of receptor tyrosine kinase signaling, is required for NRG1-induced peripheral nerve myelination. Here, we determined the role of Gab1 in the development of the NMJ using muscle-specific conditional Gab1 knockout mice. The mutant mice showed delayed postnatal maturation of the NMJ. Furthermore, the selective loss of the gab1 gene in terminal Schwann cells produced delayed synaptic elimination with abnormal morphology of the motor endplate, suggesting that Gab1 in both muscles and terminal Schwann cells is required for proper NMJ development. Gab1 in terminal Schwann cells appeared to regulate the number and process elongation of terminal Schwann cells during synaptic elimination. However, Gab2 knockout mice did not show any defects in the development of the NMJ. Considering the role of Gab1 in postnatal peripheral nerve myelination, our findings suggest that Gab1 is a pleiotropic and important component of NRG1 signals during postnatal development of the peripheral neuromuscular system.

Anatomical study of the fibularis longus muscle motor points and electrical stimulation therapy application / Estudio anatómico de los puntos motores del músculo fibularis longus y su aplicación en la terapia de electroestimulación

The fibularis longus muscle (FLM) has an important role in the movement of eversion of the foot and in maintaining the plantar arch. The electrostimulation procedures seek to maintain muscle trophism, increase strength and endurance, and are frequently used in physiotherapy, for which the clinician needs to know the location of the motor points of the FLM. Therefore, the purpose of this study was to determine the number and distribution of motor points of the FLM and relate them to observable parameters in the surface anatomy. Ten formalin-preserved limbs were used, and the lateral regions of the leg were dissected in detail. In all the cases, the muscle presented three fascicular patterns, the superior and anteroinferior fascicles presented two motor points each, while the posteroinferior fascicles were between 2 and 3 motor points. Our results suggest that there is a pattern of distribution of the superficial fibular nerve, whose knowledge is useful for clinical application in the FLM electrostimulation proceedings.

El músculo fibular largo (MFL) tiene una importante función en el movimiento de eversión del pié y en la mantención del arco plantar. Los procedimientos de electroestimulación buscan mantener el trofismo muscular, aumentar la potencia y resistencia y es frecuente su utilización en fisioterapia, para ello el clínico necesita conocer la localización de los puntos motores del MFL, por ello, el propósito de este estudio fue determinar el número y distribución de los puntos motores del MFL y relacionarlos con parámetros observables en la anatomía de superficie. Se utilizaron 10 miembros inferiores conservados y se disecó detalladamente la región lateral de la pierna. El músculo presentó en todos los casos una estructura trifascicular, los fascículos superiores y anteroinferiores presentaron dos puntos motores cada uno, mientras en el fascículo posteroinferior encontramos entre 2 y 3 puntos motores. Nuestros resultados sugieren que existe un patrón de distribución del nervio fibular superficial cuyo conocimiento es de utilidad clínica para los procedimientos de electroestimulación del MFL.

The influence of lidocaine and racemic bupivacaine on neuromuscular blockade produced by rocuronium: a study in rat phrenic nerve-diaphragm preparation / Influência da lidocaína e da bupivacaína racêmica no bloqueio neuromuscular produzido pelo rocurônio: estudo em preparação nervo frênico-diafragma de rato

PURPOSE: To evaluate in vitro lidocaine and racemic bupivacaine effects in neuromuscular transmission and in neuromuscular blockade produced by rocuronium. METHODS: Rats were distributed in 5 groups (n = 5) in agreement with the studied drugs: lidocaine, racemic bupivacaine, rocuronium, separately (Groups I, II, III); rocuronium in preparations exposed to local anesthetics (Groups IV, V). The concentrations used were: 20 µg/mL, 5 µg/mL and 4 µg/mL, for lidocaine, bupivacaine and rocuronium, respectively. It was evaluated: 1) amplitude of diaphragm muscle response to indirect stimulation, before and 60 minutes after separately addition of lidocaine, racemic bupivacaine and rocuronium and the association of local anesthetics - rocuronium; 2) membrane potentials (MP) and miniature end-plate potentials (MEPP). RESULTS: Lidocaine and bupivacaine separately didn't alter the amplitude of muscle response and MP. In preparations previously exposed to lidocaine and racemic bupivacaine, the rocuronium blockade was significantly larger (90.10 ± 9.15 percent and 100 percent, respectively), in relation to the produced by rocuronium separately (73.12 ± 9.89 percent). Lidocaine caused an increase in the frequency of MEPP, being followed by blockade; racemic bupivacaine produced decrease being followed by blockade. CONCLUSIONS: Local anesthetics potentiated the blockade caused by rocuronium. The alterations of MEPP identify presynaptic action.

OBJETIVO: Avaliar in vitro os efeitos da lidocaína e bupivacaína racêmica na transmissão neuromuscular e no bloqueio neuromuscular produzido pelo rocurônio. MÉTODOS: Ratos foram distribuídos em 5 grupos (n = 5) de acordo com a droga estudada: lidocaina, bupivacaína racêmica, rocurônio, isoladamente (Grupos I, II, III); rocurõnio em preparações expostas aos anestésicos locais (Grupos IV, V). As concentrações utilizadas foram: 20 µg/mL, 5 µg/mL e 4 µg/mL, para lidocaína, bupivacaína e rocurônio, respectivamente. Avaliou-se: 1) amplitude das respostas do músculo diafragma à estimulação indireta, antes e 60 minutos após a adição da lidocaína, bupivacaína racêmica e rocurônio isoladamente e da associação anestésicos locais - rocurônio; 2) potenciais de membrana (PM) e potenciais de placa terminal em miniatura (PPTM). RESULTADOS: A lidocaína e a bupivacaína isoladamente não alteraram a amplitude das respostas musculares e os PM. Nas preparações previamente expostas a lidocaína e a bupivacaína racêmica, o bloqueio com o rocurônio foi significativamente maior (90,10 ± 9,15 por cento e 100 por cento, respectivamente), em relação ao produzido pelo rocurônio isoladamente (73,12 ± 9,89 por cento). A lidocaína causou aumento na freqüência dos PPTM, seguido de bloqueio; a bupivacaína racêmica produziu diminuição seguida de bloqueio. CONCLUSÕES: Os anestésicos locais potencializaram o bloqueio causado pelo rocurônio. As alterações do PPTM identificam ação pré-sináptica.

Unsuspected Plasticity of Single Neurons after Connection of the Corticospinal Tract with Peripheral Nerves in Spinal Cord Lesions

OBJECTIVE: To report an unsuspected adaptive plasticity of single upper motor neurons and of primary motor cortex found after microsurgical connection of the spinal cord with peripheral nerve via grafts in paraplegics and focussed discussion of the reviewed literature. METHODS: The research aimed at making paraplegics walk again, after 20 years of experimental surgery in animals. Amongst other things, animal experiments demonstrated the alteration of the motor endplates receptors from cholinergic to glutamatergic induced by connection with upper motor neurons. The same paradigm was successfully performed in paraplegic humans. The nerve grafts were put into the ventral-lateral spinal tract randomly, without possibility of choosing the axons coming from different areas of the motor cortex. RESULTS: The patient became able to selectively activate the re-innervated muscles she wanted without concurrent activities of other muscles connected with the same cortical areas. CONCLUSION: Authors believe that unlike in nerve or tendon transfers, where the whole cortical area corresponding to the transfer changes its function a phenomenon that we call "brain plasticity by areas", in our paradigm due to the direct connection of upper motor neurons with different peripheral nerves and muscles via nerve grafts motor learning occurs based on adaptive neuronal plasticity so that simultaneous contractions of other muscles are prevented. We propose to call it adaptive functional "plasticity by single neurons". We speculate that this phenomenon is due to the simultaneous activation of neurons spread in different cortical areas for a given specific movement, whilst the other neurons of the same areas connected with peripheral nerves of different muscles are not activated at the same time. Why different neurons of the same area fire at different times according to different voluntary demands remains to be discovered. We are committed to solve this enigma hereafter.

The History of Myasthenia Gravis

Since Willis described 'fatigable weakness' in 1672, most physicians consider it as a kind of hysteria due to the inconsistent fluctuation of symptoms. Erb presented three cases of 'bulbal palsy' in the 1870s, and Oppenheim and Hopper considered myasthenia gravis as a disease similar to curare poisoning and as a disease induced by attack of the motor centers by intrinsic toxins, respectively. In 1903, Elliot suggested that a 'chemical substance' mediates the nerve impulses at synapse. However, it was not until 1921 that this was demonstrated by Loewi, who provided evidence from the famous two-frog-hearts experiment. Dale later revealed the substance to be acetylcholine, and he also suggested that myasthenia gravis is due to a problem with the motor end plate. In 1934, Walker was prompted by the resemblance between myasthenia gravis and curare poisoning to apply physostigmine, a curare-poisoning antidote, to a patient, which produced a dramatic result. Since then the use of anticholinesterase inhibitors has been adopted for standard therapeutic modality. Some prominent surgeons have also applied thymectomy as a surgical modality. The most recent focus of myasthenia gravis has been immunological. In 1960, Simpson proposed the autoimmune hypothesis, and Chang et al. showed that snake venom contained a selective antagonist of the nicotinic acetylcholine receptor, alpha-bungarotoxin. The immunization of rabbits with acetylcholine receptor purified from the electrical organs of electric eels by Patrick et al. induced myasthenic symptoms and signs, and these were reversed by acetylcholinesterase inhibitors. The role of the autoimmune system has led to the introduction of an immunosuppressive modality and plasma exchange to the field of clinical neurology.

Análisis ultraestructural del músculo levator auris longus de ratón intoxicado in vivo por la neurotoxina botulínica tipo A / Ultrastructural analysis of mouse levator auris longus muscle intoxicated in vivo by botulinum neurotoxin type A

En este estudio investigamos los cambios ultraestructurales a corto y largo plazo provocados por la toxina botulínica tipo A inyectada a dosis sub-letales in vivo en el levator auris longus de ratones. La neurotoxina actuó temporalmente sobre los terminales nerviosos e indujo una parálisis generalizada que afectó la morfología de la preparación neuromuscular estudiada influyendo sobre: tamaño y complejidad de la terminación nerviosa, población vesicular, apariencia de las mitocondrias, fisonomía de las células de Schwann, desarrollo y distribución de los pliegues de la membrana postsináptica, y morfología de los núcleos de los diferentes elementos de la placa motora. Además, la cantidad de tejido conectivo endomisial aumentó significativamente con relación a los casos control, siendo estos cambios marcados en las primeras semanas. Entre los 20 y 25 días, período correspondiente al proceso de recuperación observamos terminales nerviosos de apariencia variable, unos completamente degenerados rodeados por restos de prolongaciones de células de Schwann y otros nuevos contactos caracterizados ultraestructuralmente por su pequeño calibre y población vesicular escasa, rodeadas parcialmente por la célula de Schwann, axones tempranamente mielinizados, pliegues sinápticos escasamente desarrollados. Sesenta días posteriores a la inyección, el axón terminal recobró su apariencia normal: las vesículas sinápticas llenaban el axoplasma, las mitocondrias exhibían crestas y densidades electrónicas de apariencia habitual. Se puede concluir que la toxina botulínica tipo A provoca fenómenos de desnervación en el nervio terminal y en los componentes de la placa motora. Las células de Schwann juegan un papel importante en la recuperación morfofuncional de los terminales nerviosos y en su degradación.

Functional compensative mechanism of upper limb with root avulsion of C(5)-C(6) of brachial plexus after ipsilateral C(7) transfer / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the compensative mechanism of no further impairment of the upper limb after ipsilateral C(7) transfer for treatment of root avulsion of C(5)-C(6) of the brachial plexus.</p><p><b>METHODS</b>Sixty Sprague Dawley (SD) rats were randomly divided into a C7-transection group and a control group, 30 rats each. In the C(7)-transection group, the left forelimbs of the animals underwent transection of ipsilateral C(7) nerve root while C(5) and C(6) nerve roots were avulsed. In the control group, the left forelimbs only underwent C(5) and C(6) root avulsion. The representative muscles of C(7) (innervated mainly by C(7)) including latissimus dorsi, triceps, extensor carpi radialis brevis and extensor digitorum communis were evaluated with neurophysiological investigation, muscular histology and motor end plate histomorphometry 3, 6 and 12 weeks after operation. The right forelimbs of all rats were taken as the control sides.</p><p><b>RESULTS</b>Three weeks after operation, the recovery rates of amplitudes of compound muscle action potential (CMAP) and CMAP latency, muscular wet weight and cross-sectional area of muscle fibers, and area of postsynaptic membranes of those four representative muscles in the C(7)-transection group were significantly lower than those of the control group (P less than 0.05 or P less than 0.01). Six weeks postoperatively, the recovery rates of CMAP amplitude and latency of the triceps showed no significant difference between the C(7)-transection group and the control group (P larger than 0.05). For the extensor carpi radialis brevis and the extensor digitorum communis, the recovery rates of the cross-sectional area of muscle fibers, the amplitude and latency of CMAP and the area of postsynaptic membranes showed no significant difference between the two groups (P larger than 0.05), while the rest parameters were still significantly different between the two group (P less than 0.05 or P less than 0.01). As far as the ultramicrostructure was concerned in the C(7)-transection group, more motor end plates of four representative muscles were observed and their ultramicrostructure also had a tendency to mature as compared with those of 3 weeks postoperatively. Twelve weeks after operation, all parameters of the C(7)-transection group were not significantly different from those of the control group (P >0.05). In the C7-transection group, the motor end plates were densely distributed and their ultramicrostructure in four representative muscles appeared to be mature as compared with those of the control group.</p><p><b>CONCLUSIONS</b>After ipsilateral C(7) transfer for treatment of root avulsion of C(5)-C(6) of the brachial plexus, the nerve fibers of the lower trunk can compensatively innervate fibers of C(7)-representative muscles by means of motor end plate regeneration, so there is no further impairment on the injured upper limb.</p>

Acidic fibroblast growth factor for preventing motor endplate degeneration and muscular atrophy after motor nerve injury: a morphological and electrophysiological study / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore measures to prevent motor endplate degeneration and muscular atrophy after motor nerve injury.</p><p><b>METHODS</b>Thirty Sprague-Dawley rats were randomized into 3 equal groups. In two of the groups, the right common peroneal nerves of the rats were transected and immediately sutured with implantation of collagen gel carrier of acidic fibroblast growth factor (aFGF) or the empty carrier into the denervated tibialis anterior muscles. In the control group, the transected nerves were sutured without implantation. Six weeks after the operation, morphological and electrophysiological examinations were performed.</p><p><b>RESULTS</b>In the control rats and those with empty collagen gel carrier implantation, obvious motor endplate degeneration and muscular atrophy occurred, which were not obvious in rats receiving aFGF carrier implantation. The decrement of repetitive nerve stimulation was significantly greater in the former two groups than in the latter.</p><p><b>CONCLUSION</b>Implantation of collagen gel carrier of aFGF may prevent motor endplate degeneration and facilitate functional recovery of the neuromuscular junction after motor nerve injury.</p>

Histochemical changes of muscle fibers and motor end-plates of paravertebral muscles in scoliosis associated with syringomyelia / 中国医学科学院学报

<p><b>OBJECTIVE</b>To study the histochemical changes of muscle fibers and motor end-plates of paravertebral muscles, and analyze their relationship with the etiology of scoliosis associated with syringomyelia as compared with adolescent idiopathic scoliosis (AIS) and non-scoliotic patients.</p><p><b>METHODS</b>All the enrolled patients were divided into three groups: Group I consisted of 20 patients with scoliosis associated with syringomyelia, Group II included 16 patients with AIS, and Group III included 10 patients without scoliosis. Bilateral biopsy of paravertebral muscles was performed during scheduled spinal surgery. HE staining, nicotin-lateral biopsy of paravertebral muscles was performed during scheduled spinal surgery. HE staining, nicotinamide adenine dinucleotide hydrogen-tetrazolium reductase ( NADH-TR), and alpha-naphthyl acetate esterase staining techniques were used for histological evaluation. Neurogenic and myogenic pathological changes and changes of motor end-plates of paravertebral muscles were compared among these three groups.</p><p><b>RESULTS</b>Neurogenic pathological changes of muscle fibers were found in 12 (60% ) patients in Group I but was not found in Group II and III. The numbers of both T0 type motor end-plates and pathological end-plates on the convex side were significantly larger than those on the concave side in Group I ( P < O. 05 ). In Group II , however, the numbers of both T0 type motor end-plates and pathological end-plates on the concave side were significantly larger than those on the convex side (P < 0.05). No significant difference was found between two sides in Group III.</p><p><b>CONCLUSION</b>The histochemical changes of paravertebral muscles in patients with scoliosis and syringomyelia are different from those in AIS patients. It is suggested that a primary denervation of paravertebral muscles exist in scoliosis associated with syringomyelia, which may play a role in the pathogenesis of scoliosis.</p>

Changes of acetylcholine receptor distribution at the motor end-plates following muscle transfer / 中华整形外科杂志

<p><b>OBJECTIVE</b>To investigate the changes of acetylcholine receptor (AChR) distribution at the neuromuscular junction (i.e. motor end-plate) following the free neurovascular muscle transfer.</p><p><b>METHODS</b>AChR in the gracilis muscle of the Wistar rat following free neurovascular transfer were labeled by fluorescent alpha-bungarotoxin and radioiodinated alpha-bungarotoxin. Then confocal microscope and gamma-counting were estimated to ACHR, qualitatively and quantitatively.</p><p><b>RESULTS</b>The junctional AChR numbers decreased to a minimum at the fourth week postoperatively, whereas the extrajunctional receptor numbers increased. From the fifth week postoperatively, the number of junctional AChR's increased. Even at 30 weeks after transfer, the morphology of the neuromuscular junction failed to return to the preoperative style. The number of acetylcholine receptors at the reinnervated neuromuscular junction also remained lower than the control.</p><p><b>CONCLUSION</b>The persistent weakness following free neurovascular muscle transfer may be attributed to these qualitative and quantitative changes at the neuromuscular junction.</p>

Pattern of Reinnervation in Denervated Rat Gastrocnemius Muscle by Various Procedures of Reinnervation / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: We tried to investigate the effectiveness of various methods of reinnervation including nerve-muscle pedicle transfer, nerve anastomosis, nerve implantation. MATERIALS AND METHOD: Forty Sprague-Dawley rats were used. Control group and experimental groups each consisted 5 rats, as follows: a denervated tibial nerve without reinnervation (control), a common peroneal nerve and 2X2 mm tibialis anterior muscle pedicle grafted to the denervated gastrocnemius muscle after the removal of epimysium (group I), a common peroneal nerve and 4X4 mm tibialis anterior muscle pedicle grafted to the denervated gastrocnemius muscle after the removal of epimysium (group II), a common peroneal nerve and 2X2 mm tibialis anterior muscle pedicle grafted to the denervated gastrocnemius muscle after removal of epimysium and part of muscle (group III), a common peroneal nerve and 4X4 mm tibialis anterior muscle pedicle grafted to the denervated gastrocnemius muscle after removal of epimysium and part of muscle (group IV), a common peroneal nerve and 2X2 mm tibialis anterior muscle pedicle inserted to the denervated gastrocnemius muscle (group V), a common peroneal nerve inserted to the denervated gastrocnemius muscle (group VI), and anastomesed common peroneal nerve to distal tibialis nerve (group VII). Electromyography, muscle contraction power study, histotological analysis and counting of motor end-plate were applied for estimating the reinnervation of denervated muscle. RESULTS: In motor nerve conduction studies, Group VII and III showed significantly higher amplitude of the compound muscle action potentials than other groups. In muscle contraction power studies, Group VII and III showed significantly powerful contraction. In histological analysis, group VII and III showed less muscle atrophy. The motor end-plate count was more in the groups VII, III, I, V, VI, II and IV in order. CONCLUSION: Nerve anastomosis and 2X2 mm nerve-muscle pedicle transfer showed more successful regeneration of denervated muscle than other reinnervation methods including nerve implantation.

Protective effects of ciliary neurotrophic factor on denervated skeletal muscle / 华中科技大学学报（医学）（英德文版）

To study the effects of ciliary neurotrophic factor (CNTF) on denervated skeletal muscle atrophy and to find a new approach to ameliorate atrophy of denervated muscle, a model was established by cutting the right sciatic nerve in 36 Wistar mice, with the left side serving as control. Then they were divided into two groups randomly. CNTF (1 U/ml) 0.1 ml was injected into the right tibial muscle every day in experimental group, and saline was used into another group for comparison. The muscle wet weight, muscle total protein, Ca2+, physiological response and morphology were analyzed on the 7th, 14th and 28th day after operation. Our results showed that compared to control group, there was a significant increase in muscle wet weight, total protein, Ca2+, muscle fiber cross-section area in CNTF group (P < 0.05). CNTF could ameliorate the decrease of tetanic tension (PO), post-tetanic twitch potentiation (PTP), and the prolonged muscle relaxation time (RT) caused by denervation (P < 0.05). The motor end-plate areas 7 days and 14 days after denervation was similar (P > 0.05), but significantly larger 28 days after the denervation (P < 0.05). Our results suggest that CNTF exerts myotrophic effects by attenuating the morphological and functional changes associated with denervation of rat muscles and has protective effects on denervated muscle and motor end plate.

Adult albino rats; study of motor units innervated by tibial nerve

The average number and size of motor units were assessed by investigating the components of motor units supplied by Tibial Nerve in adult albino rats. The motor neurons forming the Tibial Nerve localized by HRP technique extended from the caudal part of L3 to S 1 segments of the spinal cord. The motoneurons forming the Tibial Nerve [TN] which are distributed mainly in the Posterolateral and Post-Posterolateral groups with few of them are also distributed in the central groups. The average somal diameter of motoneurons ranged between 12 and 63 m. The motor end-plates on skeletal myofibers of muscles supplied by Tibial Nerve were localized by using bromo-indigo and urea-silver technique. The total of 826 motor units with the size of 137 of the muscles innervated by Tibial Nerve have been observed in the present study

Aspectos patológicos del músculo esquelético debido a la infección experimental por trypanosoma cruzi / Pathological aspects of skeletal muscle in experimental trypanosoma cruzi infection

En este estudio se muestran los signos clínicos desarrollados por ratones durante la fase aguda de la infección producida por tres cepas de trypanosoma cruzi. Los ratones infectados con la cepa Dm74 sufrieron alteración de la mobilidad de los miembros posteriores y murieron durante la fase aguda de la infección. El análisis histológico del músculo esquelético mostró infiltrado inflamatorio de leucocitos mononucleares y polimorfonucleares, fibroblastos, eritrocitos libres y depósitos de IgG en el espacio intersticial del Gastrocnemius (G). La desintegración de las microfibrillas y cambios en la microvasculatura, fibras nerviosas y en la unión neuromuscular del G fueron también observados. Estos resultados indican que la infección aguda producida por T. cruzi causa daño progresivo en la fibra muscular esquelética y alteración de la actividad motora

Basic fibroblast growth factor-immunoreactivity in the peripheral nerve and motor endplate of the rat

Using immunohistochemistry and immuno-electron microscopy, the distribution of basic fibroblast growth factor [bFGF] in the peripheral nerves and motor endplates of the adult rat was investigated. The study concluded that the localization of bFGF in the peripheral nerve and motor endplate, as seen in the present study, was compatible with the functions ascribed for this protein in the peripheral motor system

A Comparative Study of Nerve Regeneration on End-to-Side and End-to-End Neurorrhaphy in Rats

The surgical methods of injured peripheral nerve were limited to end-to-end neurorrhaphy, nerve graft, neurotization, etc. Recently, Several studies were executed about end-to-side neurorrhaphy in peripheral nerve injury. The purpose of this study is to investigate the axonal regeneration of end-to-side neurorrhaphy in rats, as alternative surgical method for peripheral nerve injury comparing with the state of normal, denervated, and end-to-end neurorrhaphy. Sixty female Sprague-Dawley rats were divided into four groups; group I as normal control group, group II as denervated control group, group III as end-to-end neurorrhaphy group, group IV as end-to-side neurorrhaphy group. At postoperative 4, 8, 12, 16, 20 and 24 week, nerve regeneration was assessed through electrophysiologic and histological studies. The results obtained were as follows: 1. In electrophysiologic test, the mean amplitude was higher in normal control group(group I) than either in end-to-end neurorrhaphy group(group III) or in end- to- side neurorrhaphy group(group IV)(p < 0.05). But there is no significant difference between group III and group IV. 2. The mean number of regenerating myelinated nerve fibers was higher in group I than either in group III or in group IV(p < 0.05). But there is no significant difference between group III and group IV, except at postoperative 16 week. 3. The mean number of motor end-plates at postoperative 24 week was 20.5 in group III and 18.2 in group IV, but there is no significant difference between group III and group IV. In conclusion, end-to-side neurorrhaphy through an epineural window could induce distal nerve regeneration by collateral sprouting of main peripheral nerve and positively reflected in functional improvement of the target muscle.

Histopathologic Findings and Muscle Fiber Conduction Studies after Intra-muscular Injection of Botulinum Toxin in Rat

Recently, botulinum toxin has been widely used for the management of spasticity. However it's mechanism of action in the skeletal muscle has not been well clarified. This study was performed to investigate the histopathologic changes in the skeletal muscle after botulinum toxin injection, and to determine the clinical standards of muscle fiber conduction study as an objective indicator for the changes of muscle fiber. As a study group, 35 Sprague Dawley rats were injected intra-muscularly with the botulinum toxin type A around two heads of right gastrocnemius muscle. After the injection of botulinum toxin, histopathologic studies and muscle fiber conduction studies were performed in 5 rats of the study group at 0, 1, 3, 5, 7, 14, and 28th day respectively. Based on the morphologic studies, the mechanisms of paralysis following the botulinum toxin injection were found to be both myogenic and neurogenic, and the motor function recovered through the formation of new motor end-plate and proliferation of Schwann cells. The muscle fiber conduction study revealed that the mean latencies of study group at 1, 3, 5, 7, and 14th day after the injection of botulinum toxin were significantly prolonged than those of the control group(p<0.05). The prolongation and slow recovery of latencies in a muscle fiber conduction study after the injection of botulinum toxin significantly reflect the morphologic changes of paralized skeletal muscles.