Extracellular matrix of ostrich articular cartilage

The composition and organization of the extracellular matrix of ostrich articular cartilage was investigated, using samples from the proximal and distal surfaces of the tarsometatarsus. For morphological analysis, sections were stained with toluidine blue and analyzed by polarized light microscopy. For biochemical analysis, extracellular matrix components were extracted with 4 M guanidinium chloride, fractionated on DEAF-Sephacel and analyzed by SDS-PAGE. Glycosaminoglycans were analyzed by electrophoresis in agarose gels. Structural analysis showed that the fibrils were arranged in different directions, especially on the distal surface. The protein and glycosaminoglycan contents of this region were higher than in the other regions. SDS-PAGE showed the presence of proteins with molecular masses ranging from 17 to 121 kDa and polydisperse components of 67, 80-100, and 250-300 kDa in all regions. The analysis of glycosaminoglycans in agarosepropylene diamine gels revealed the presence of only chondroitin-sulfate. The electrophoretic band corresponding to putative decorin was a small proteoglycan containing chondroitin-sufate and not dermatan-sulfate, unlike other cartilages. The higher amounts of proteins and glycosaminoglycans and the multidirectional arrangement of fibrils seen in the distal region may be correlated with the higher compression normally exerted on this region.291475

Organization of collagen bundles during tendon healing in rats treated with L-NAME

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The Achilles tendon can support high tension forces and may experience lesions. The damaged tissue does not regenerate completely, with the organization and mechanical properties of the repaired tendon being inferior to those of a healthy tendon. Nitric oxide (NO) plays an important role in wound repair. We have examined the structural reorganization and repair in Achilles tendon after injury in rats treated with the NO synthase inhibitor L-NAME. The right Achilles tendon of male Wistar rats was partially transected. One group of rats was treated with L-NAME (similar to 300 mg/kg per day, given in drinking water) for 4 days prior to tendon sectioning and throughout the post-operative period. Control rats received water without L-NAME. The tendons were excised at 7, 14, and 21 days post-injury and used to quantify hydroxyproline and for mechanical tests. Tendons were also processed for histomorphological analysis by polarized light microscopy, which showed that the collagen fibers were disorganized by day 7 in non-treated and L-NAME-treated rats. In non-treated rats, the organization of the extracellular matrix was more homogeneous by days 14 and 21 compared with day 7, although this homogeneity was less than that in normal tendon. In contrast, in injured tendons from L-NAME-treated rats, the collagen fibers were still disorganized on day 21. Tendons from treated rats had more hydroxyproline but lower mechanical properties compared with those from non-treated rats. Thus, NO modulates tendon healing, with a reduction in NO biosynthesis delaying reorganization of the extracellular matrix, especially collagen.3372235242Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Effect of high intensity aerobic exercise and mesterolone on remodeling of Achilles tendon of C57BL/6 transgenic mice

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The effect of mesterolone and intensive treadmill training (6 weeks, 5 days/week, means: 15.82 m/min and 45.8 min/day) in Achilles tendon remodeling was evaluated. Sedentary mice treated with mesterolone (Sed-M) or vehicle (Sed-C, placebo/control) and corresponding exercised (Ex-M and Ex-C) were examined. SDS-polyacrylamide gel electrophoresis was used for determining collagen bands and hydroxyproline concentration. Collagen fibril diameter, the area and number of fibrils contained in an area probe, and the ultrastructure of fibroblasts (tenocytes) were determined. The presence of collagen was notable in the tendons of all groups. Collagen alpha(1/)alpha(2) bands in Sed-M, Ex-C, and Ex-M were higher than in Sed-C, as shown by hydroxyproline content, but collagen beta-chain appeared only in Ex-C. Noticeable bands of non-collagenous proteins were found in Sed-M and Ex-M. The number of fibrils in the area probe increased markedly in Sed-M and Ex-C (12-fold), but their diameter and area were unchanged compared with Sed-C. In Ex-M, the fibril number decreased by three-fold to 3.5-fold compared with Sed-M and Ex-C, whereas diameter and area increased. Sed-C tenocytes appeared quiescent, whereas those in the other groups seemed to be engaged in protein synthesis. The density of tenocytes was smaller in Sed-C than in Ex-C, Sed-M, and Ex-M. Thus, mechanical stimuli and mesterolone alter the morphology of tenocytes and the composition of the tendon, probably through fibrillogenesis and/or increased intermolecular cross-links. The ergogenic effect is evidenced by the activation of collagenous and non-collagenous protein synthesis and the increase in the diameter and area of collagen fibrils. This study might be relevant to clinical sports medicine.3392411420Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [04/13767-9]CNPq [522131/95-6]FAPESP [04/13768-5

Effects of stretching on morphological and biochemical aspects of the extracellular matrix of the rat calcaneal tendon

Several studies have demonstrated the relationship between exercise and the extracellular matrix of muscle tendons, and have described alterations in their structural and biochemical properties when subjected to strenuous exercise. However, little is known about what happens to tendons when they are subjected to stretching. We evaluated the changes in the composition and structure of rat calcaneal tendons subjected to a stretching program. The animals had their muscles stretched for 30 s with 30 s of rest, with 10 repetitions, three and five times a week for 21 days. For morphological analysis, the sections were stained with hematoxylin-eosin and toluidine blue. For biochemical analysis, the tendons were treated with 4 M guanidine hydrochloride and analyzed in SDS-PAGE. The contents of total proteins and glycosaminoglycans were also measured. In the sections stained with toluidine blue, we could observe an increase of rounded cells, especially in the enthesis region. In the region next to the enthesis was a metachromatic region, which was more intensely stained in the stretched groups. In the tension regions, the cells appeared more aligned. Cellularity increased in both regions. The SDS-PAGE analysis showed a larger amount of collagen in the stretched groups and a polydispersed component of 65 kDa in all the groups. The amounts of proteins and glycosaminoglycans were also larger in the stretched tendons. The agarose-gel electrophoresis confirmed the presence of dermatan sulfate in the tension and compression regions, and of chondroitin sulfate only in the latter. Our results showed that the stretching stimulus changed the cellularity and the amount of the extracellular matrix compounds, confirming that tendons are dynamic structures with a capacity to detect alterations in their load.34219710