Morphological aspects of rabbit masseter muscle after cervical sympathectomy

The objective of this paper was to study the effect of sympathetic innervation on morphological and histochemical aspects of skeletal muscle tissue. Rabbit masseter muscle was studied using histochemical and immunohistochemical methods for periods of up to 18 months post-sympathectomy. The morphological and enzymatic characteristics of control masseter muscles were similar on both the left and right sides. The main features were muscle fibres with a mosaic pattern and a predominance of type IIa fibres, followed by type I. Type IIb fibres showed very low frequency. Sympathectomized animals showed varying degrees of metabolic and morphological alterations, especially 18 months after sympathectomy. The first five groups showed a higher frequency of type I fibres, whilst the oldest group showed a higher frequency of type lib fibres. In the oldest group, a significant variation in fibre diameter was observed. Many fibres showed small diameter, atrophy, hypertrophy, splitting, and necrosis. Areas with fibrosis were observed. Thus cervical sympathectomy induced morphological alterations in the masseter muscles. These alterations were, in part, similar to both denervation and myopathy. These findings indicate that sympathetic innervation contributes to the maintenance of the morphological and metabolic features of masseter muscle fibres.

Laryngeal electromyography: Contribution to vocal fold immobility diagnosis

Laryngeal Electromyography (LEMG) is a diagnostic test commonly used in patients with vocal fold movement disorder The aim of this study is to describe LEMG in patients with vocalfold immobility. A total of 55 dysphonic patients with vocal fold immobility diagnosed by laryngeal endoscopy were grouped according to probable clinical cause: 1) unknown; 2) traumatic; or 3) tumoral compression. They were submitted to LEMG by percutaneous insertion of concentric needle electrode. LEMG was conclusive in all patients and showed a majority with peripheral nerve injury. LEMG diagnosed peripheral nerve damage in 25 group 1, 12 group 2, and 11 group 3 patients. LEMG was normal in 4 patients, suggesting cricoarytenoid joint fixation. Central nervous system disorders was suggested in 2 and myopathic pattern in 1. As the major cause of vocal fold immobility is peripheral nerve damage, LEMG is an important test to confirm diagnosis.

Heart failure alters MyoD and MRF4 expressions in rat skeletal muscle

Heart failure (HF) is characterized by a skeletal muscle myopathy with increased expression of fast myosin heavy chains (MHCs). The skeletal muscle-specific molecular regulatory mechanisms controlling MHC expression during HF have not been described. Myogenic regulatory factors (MRFs), a family of transcriptional factors that control the expression of several skeletal muscle-specific genes, may be related to these alterations. This investigation was undertaken in order to examine potential relationships between MRF mRNA expression and MHC protein isoforms in Wistar rat skeletal muscle with monocrotaline-induced HF. We studied soleus (Sol) and extensor digitorum longus (EDL) muscles from both HF and control Wistar rats. MyoD, myogenin and MRF4 contents were determined using reverse transcription-polymerase chain reaction while MHC isoforms were separated using polyacrylamide gel electrophoresis. Despite no change in MHC composition of Wistar rat skeletal muscles with HF, the mRNA relative expression of MyoD in Sol and EDL muscles and that of MRF4 in Sol muscle were significantly reduced, whereas myogenin was not changed in both muscles. This down-regulation in the mRNA relative expression of MRF4 in Sol was associated with atrophy in response to HF while these alterations were not present in EDL muscle. Taken together, our results show a potential role for MRFs in skeletal muscle myopathy during HF. © 2006 Blackwell Science Ltd.

Alterações eletromiográficas e histopatológicas da musculatura de cães naturalmente infectados por Leishmania infantum

The aim of this study was to evaluate the electromyographic and histopathological changes in skeletal muscles of dogs naturally infected by L. infantum. Twenty five mixed breed adult dogs with parasitological, molecular and serological diagnosis were selected. The evaluated muscles were: triceps brachial, extensor carpi radialis, biceps femoris and gastrocnemius. One dog had locomotor clinical signs with hind limbs paresis associated with severe muscle atrophy. Twenty-three (92%) had some type of muscular change, and in 22 (88%) such changes were directly identified by electromyography. Even without any clinical signs of the disease, 10 (40%) dogs had electromyographic and histopathological changes. Leishmania antigens were detected in muscles of four (16%) dogs. The electromyographic evaluation indicated the occurrence of chronic polymyositis in 13 (52%) dogs, the presence of both acute and chronic muscle inflammation four (16%), acute myopathy in two (8%) and absence of electromyographic abnormalities in three (12%) dogs. The most frequently observed histopathological changes were degeneration and necrosis of myofibers and inflammatory infiltration observed in 12 (48%) dogs. Other changes were decreased diameter of muscle fibers in 15 (60%) and peri or endomysial fibrosis in 14 (56%) animals. The changes observed in the present study showed that even in the absence of clinical signs, most dogs infected by Leishmania infantum have chronic polymyositis.

Avaliação bioquímica, morfológica e funcional do músculo estriado esquelético de ratos na insuficiência cardíaca

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise dos receptores de acetilcolina (nAChRs) na musculatura esquelética de ratos com insuficiência cardíaca submetidos ao treinamento aeróbico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Expressão dos fatores de regulação miogênica, composição das miosinas e trofismos no músculo esquelético periférico de ratos com insuficiência cardíaca crônica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização morfológica, bioquímica e molecular do músculo esquelético sóleo de ratos espontaneamente hipertensos com insuficiência cardíaca

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Perfil global de expressão de micro-RNAs no músculo esquelético de ratos com insuficiência cardíaca

Pós-graduação em Ciências Biológicas (Genética) - IBB

Avaliação eletrofisiológica e histopatológica do músculo estriado esquelético em cães naturalmente acometidos pela leishmaniose visceral

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Prevalência de equinos quarto de milha portadores das mutações causadoras da miopatia por acúmulo de polissacarídeo tipo 1, paralisia periódica hipercalêmica e hipertermia maligna no Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aerobic training attenuates nicotinic acetylcholine receptor changes in the diaphragm muscle during heart failure

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Morphological aspects of rabbit masseter muscle after cervical sympathectomy

The objective of this paper was to study the effect of sympathetic innervation on morphological and histochemical aspects of skeletal muscle tissue. Rabbit masseter muscle was studied using histochemical and immunohistochemical methods for periods of up to 18 months post-sympathectomy. The morphological and enzymatic characteristics of control masseter muscles were similar on both the left and right sides. The main features were muscle fibres with a mosaic pattern and a predominance of type IIa fibres, followed by type I. Type IIb fibres showed very low frequency. Sympathectomized animals showed varying degrees of metabolic and morphological alterations, especially 18 months after sympathectomy. The first five groups showed a higher frequency of type I fibres, whilst the oldest group showed a higher frequency of type IIb fibres. In the oldest group, a significant variation in fibre diameter was observed. Many fibres showed small diameter, atrophy, hypertrophy, splitting, and necrosis. Areas with fibrosis were observed. Thus cervical sympathectomy induced morphological alterations in the masseter muscles. These alterations were, in part, similar to both denervation and myopathy. These findings indicate that sympathetic innervation contributes to the maintenance of the morphological and metabolic features of masseter muscle fibres.

Aerobic training attenuates nicotinic acethylcholine receptor changes in the diaphragm muscle during heart failure

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)