Proline metabolism in vivo was studied during the development of immobilization osteoarthritis in rabbits. Collagen content was measured as the hydroxyproline concentration of the tissue in question. The incorporation of [3H]proline was used as the indicator for total protein synthesis; collagen synthesis rate was estimated from measurements of the specific radioactivity of hydroxyproline. Cartilage samples from knee and hip joints were analysed after 3, 7, 11, 18, 35 and 56 days of immobilization. The total protein and collagen synthesis rates of the immobilized legs increased and reached a maximum after 11-35 days. Although they decreased thereafter, these rates remained elevated to the end of the experiment. A slight increase in the synthetic activity of the non-immobilized contralateral legs was also detected after 7--18 days of immobilization. The isotope incorporation was markedly higher in tibial marginal tissue than in weight-bearing cartilage. In spite of the increased synthesis, no clear changes were found in the collagen content of the tissues studied during the experiment.
Osteoarthritis was produced by the immobilization of rabbit knees in extension for 1–8 weeks (with a subsequent mobilization period of 0 or 8 weeks). The development of articular surface changes in the tibia, the femur and the patella was examined with scanning electron microscopy (SEM). During the development of osteoarthritis the normal undulations and fine regular fibre network disappeared, the number of fibres and the variation in the thickness of the fibre bundles increased, and scaly irregularities appeared. Some degenerative changes in the contralateral, non‐immobilized hind limb also appeared. The normal features of the articular surface of the patella differed from that of the tibial and femoral condyles. The changes seen with SEM correlated well with histological and biochemical results of earlier studies, but, at 1 week of immobilization, the SEM changes were more readily apparent than the histological changes. The SEM method seems to be useful for the study of articular surfaces;
Effects of motion load changes on tendon tissues and articular cartilage. A biochemical and scanning electron microscopic study on rabbits. by Videman T, Eronen I, Candolin T The motion load of rabbits was increased by treadmill running during a 5-d period. One group ran on a level surface, while the other ran uphill. After the running, the glycosaminoglycan metabolism and scanning electron microscopic photographs of different tendon, ligament and cartilage samples were analyzed. Uphill running decreased the glycosaminoglycan metabolism of articular and costal cartilage. The clearest irregularities of articular cartilage studied by scanning electron microscopy were also seen in the uphill running group. Increasing the motion load increased the glycosaminoglycan synthesis of stretched tendons. The possible combination of general inhibitory and local stimulating effects is discussed.
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