ABSTRACT
BACKGROUND: Previous studies have found that continuous loading pressure can induce intervertebral disc degeneration by reducing the number of nucleus pulposus cells and reducing the expression of extracellular matrix in the nucleus pulposus. However, its mechanism of action is unclear. OBJECTIVE: To study the effect of continuous loading pressure on apoptosis and Wnt/β-catenin signaling pathway in nucleus pulposus cells. METHODS: The in vitro models of rabbit spinal motion segment under loading pressure were established and divided into control group (no treatment), pressure group (3 kg continuous loading pressure) and observation group (3 kg continuous loading pressure + 20 μmol/L SB216763). After 3 days of intervention, the pathological changes of nucleus pulposus cells were detected by hematoxylin-eosin staining, and the expression of caspase-3 and GSK-3β protein in nucleus pulposus tissue was detected by western blot assay.
ABSTRACT
Trunk motion and the mechanisms of postural control during pedaling was investigated by analyzing the lower trunk muscle activity and spinal motion.<BR>Eight healthy adult men were assigned to pedal at the rate of 60 cycles per min. with the load of 100 W, 150 W and 200 W. Muscle activity was recorded with the surface electrodes from the m. multifidus, m, iliocostalis, m. obliquus externus, m; rectus abdominis, m. rectus lemons, m. adductor longus and m. semitendinosus. Spinal motion was filmed with 8 mm video camera located 5 m behind the subject and 1 m above the floor, and five markers were attached on the midline of the spine (C 7, Th 6, Th 12, S 1, Co) .<BR>Muscle activity (iEMG) was quantified by integrating one cycle of recorded electromyogram, and significant increase was recognized in the trunk muscles and m. rectus femoris as the load increased. The angles between each segments were calculated and the largest deviation was observed in the lumbo-sacral portion. Focussing on the activity of the m. obliquus externus, four patterns of controling the trunk posture were observed, and as the load increased, the activity patterns changed in four subjects and the other four showed tremendous increase in iEMG without changing the pattern.<BR>The results sugest that the pedaling may cause relatively large motion at lambo-sacral portion of the spine, and either the change in the activity pattern or the increase in the activity level of the trunk muscles, such as m, obliquus externus, should contribute to reduce the stress on the lambo-sacral portion.