RESUMEN
ABSTRACT: Analysis of locomotion is often used as a measure for impairment and recovery following experimental peripheral nerve injury. Compared to rodents, sheep offer several advantages for studying peripheral nerve regeneration. In the present study, we compared for the first time, two-dimensional (2D) and three-dimensional (3D) hindlimb kinematics during obstacle avoidance in the ovine model. This study obtained kinematic data to serve as a template for an objective assessment of the ankle joint motion in future studies of common peroneal nerve (CP) injury and repair in the ovine model. The strategy used by the sheep to bring the hindlimb over a moderately high obstacle, set to 10% of its hindlimb length, was pronounced knee, ankle and metatarsophalangeal flexion when approaching and clearing the obstacle. Despite the overall time course kinematic patterns about the hip, knee, ankle, and metatarsophalangeal were identical, we found significant differences between values of the 2D and 3D joint angular motion. Our results showed that the most apparent changes that occurred during the gait cycle were for the ankle (2D-measured STANCEmax: 157±2.4 degrees vs. 3D-measured STANCEmax: 151±1.2 degrees; P<.05) and metatarsophalangeal joints (2D-measured STANCEmin: 151±2.2 degrees vs. 3D-measured STANCEmin: 162 ± 2.2 degrees; P<.01 and 2D-measured TO: 163±4.9 degrees vs. 3D-measured TO: 177±1.4 degrees; P<.05), whereas the hip and knee joints were much less affected. Data and techniques described here are useful for an objective assessment of altered gait after CP injury and repairin an ovine model.
RESUMO: A análise da locomoção é frequentemente usada como uma medida para avaliar a disfunção e sua recuperação após lesão nervosa periférica experimental. Quando comparadas com os roedores, as ovelhas oferecem várias características atrativas como modelo experimental para o estudo da regeneração nervosa periférica. Não existem estudos acerca dos resultados da locomoção após lesão e reparação do nervo periférico no modelo ovino. No presente estudo, realizámos e comparámos a cinemática bidimensional (2D) e, pela primeira vez, tridimensional (3D) do membro pélvico durante a ultrapassagem de obstáculos no modelo ovino. Este estudo teve como objetivo obter dados cinemáticos para servir de modelo para uma avaliação objetiva do movimento articular do tornozelo em estudos futuros de lesão e reparação do nervo fibular comum (FC) no modelo ovino. A estratégia usada pelas ovelhas para elevar o membro pélvico sobre um obstáculo com uma altura moderada, fixado em 10% do seu comprimento, caracteriza-se por uma flexão pronunciada do joelho, tornozelo e metatarso-falangeana ao se aproximar e ultrapassar o obstáculo. Apesar dos padrões cinemáticos do quadril, joelho, tornozelo e metatarso-falangeano terem sido idênticos, foram encontradas diferenças significativas entre os valores do movimento angular das articulações em 2D e 3D. Os nossos resultados mostram que as mudanças mais aparentes que ocorreram durante o ciclo da marcha foram nas articulações do tornozelo (em 2DSTANCEmax: 157±2.4 graus vs. em 3D STANCEmax: 151±1.2 graus; P<.05) e metatarso-falangeana (em 2D STANCEmin: 151±2.2 graus vs. em 3D STANCEmin: 162 ± 2.2 graus; P<.01 e em 2D TO: 163±4.9 graus vs. em 3D TO: 177±1.4 graus; P<.05), enquanto as articulações do quadril e do joelho foram muito menos afetadas. É provável que os dados e técnicas descritas aqui sejam úteis para uma avaliação objetiva das alterações na marcha após lesão e reparação do PC no modelo ovino.
RESUMEN
Apoptosis occurs in normal tissues and in many pathological conditions, and is regulated by a variety of genes. In this work, we used electron microscopy and the comet assay to study the morphological and biochemical (DNA cleavage) changes associated with apoptosis in long-term denervated rat skeletal muscle. Male Wistar rats were anesthetized with sodium pentobarbital (30 mg/kg, i.p.), and the sciatic nerve was cut at mid-thigh level followed by the excision of a 5-10 mm long segment of the nerve. Rats that were studied more than four months after the operation were re-operated at least every three months. Samples were obtained from red (soleus) and white (extensor digitorum longus, EDL) striated skeletal muscle at different times after denervation. The ultrastructural changes associated with fiber atrophy appeared earlier and were more evident in red than in white muscle. Degenerated fibers frequently contained normal and altered (ghost-like) nuclei, which suggested repair by satellite cells. Apoptotic nuclei were seen in both muscles. There were no differences in the ultrastructural alterations associated with apoptosis in red and white muscles at any stage after denervation. Apoptosis was also confirmed by the comet assay, which showed the presence of many apoptotic cells, but revealed no significant difference between the two muscle types. Overall, these results suggest that the long-term denervation of red and white skeletal muscles causes atrophy and apoptosis, with the latter probably being responsible for the muscle fiber loss after long-term denervation.