Alterações no tendão de Aquiles após inflamação em tecido adjacente / Alterations in the Achilles tendon after inflammation in surrounding tissue

OBJETIVO: Analisar as características de tendões de Aquiles de ratos após indução de processo inflamatório localizado na pata. MÉTODOS: Foram utilizados três grupos experimentais: grupo inflamado com carragenina na pata de rato (G1); grupo salina (G2) e grupo controle (G3). Após 4 horas os animais foram eutanaziados e o tendão de Aquiles foi removido. RESULTADOS:Não foram observadas diferenças significativas nas análises de proteínas não colagênicas, glicosaminoglicanos e hidroxiprolina, mas uma tendência a diminuição foi verificada em G1. Em organização de moléculas de colágeno não foram observadas diferenças entre os grupos. Com respeito à atividade de MMPs, foi observada uma presença maior da isoforma ativa da MMP-2 em G1, sugerindo que a remodelação do tecido está ocorrendo. CONCLUSÃO: Desta forma, nós concluímos que o processo inflamatório desencadeado em pata de rato pode afetar o remodelamento de tendões situados próximo ao local inflamado. Nível de Evidência I, Estudos Prognósticos - Investigação do Efeito de Característica de um Paciente Sobre o Desfecho da Doença.

OBJECTIVE: To analyze the characteristics of the Achilles tendon of rats after induction of localized inflammation in the rat paw. METHODS: In our study three groups were used: inflamed group with carrageenan in rat paw (G1); saline group (G2) and control group (G3). After 4 hours the animals were euthanized and the Achilles tendon removed. RESULTS: No significant differences were observed in the analysis of non-collagenous proteins, glycosaminoglycans and hydroxyproline in the groups but a tendency of reduction was verified in G1. About the organization of collagen molecules, no differences were observed between groups. With respect to MMPs activity, a stronger presence of the active isoform of MMP-2 in G1 was observed, suggesting that the remodeling was occurring. CONCLUSION: Thus, we conclude that the inflammatory process in rat paw may affect the remodeling of tendons located near the inflamed site. Level of Evidence I, Prognostic Studies - Investigating the Effect of a Patient Characteristic on the Outcome of Disease.

Physicochemical and structural analysis of three regions of the deep digital flexor tendon of pigs

Few studies have discussed the relationship between the molecular organization and the physicochemical and biomechanical properties of pig tendons. In this work, we examined the extracellular matrix of the deep digital flexor tendon of pigs, which was subjected to tensional (proximal region) and compressive (distal and terminal regions) forces. The three regions of the tendon were used for swelling tests and their glycosaminoglycan content was determined. Longitudinal sections of the tendon were stained and observed using polarized light microscopy. The distal and terminal regions were swole more in water than the proximal region. After staining with toluidine blue the metachromasy was more intense in the distal and terminal regions, indicating an accumulation of proteoglycans in these regions. Analysis of the glycosaminoglycans by agarose gel electrophoresis showed that dermatan sulfate was present in all regions, whereas chondroitin sulfate occurred only in the regions of compression. The shape of the fibroblasts changed along the tendon: rounded cells occurred in regions under compression, while in the region under tension, elongated cells predominated. The organization and distribution of the collagen bundles were different for each region. Birefringence analysis revealed a more regular crimp pattern in the region under tension than in the regions under compressive forces. The elastic fibers also showed a different distribution in each region. These results indicate that the regional differences in the structure and composition of the deep digital flexor tendon of pigs are related to the biomechanical properties of the tendon.

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 DEAE-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

Effects of aggrecan on schwann cell migration in vitro and nerve regeneration in vivo

Although the role of many small proteoglycans in regeneration of the nervous system has been established, little is known about the involvement of large proteoglycans. In this study, we evaluated the effects of aggrecan, a high molecular mass proteoglycan, on Schwann cells in vitro and investigated its effects on axonal regeneration after sciatic nerve tubulization. The number of regenerated axons and their morphometrical parameters were determined in vivo. Aggrecan increased the number and viability of Schwann cells in vitro. Similarly, the number of regenerated fibers increased significantly when aggrecan was applied in vivo, but there were no alterations in the morphometrical parameters. These results indicate that aggrecan contributes to the regeneration of peripheral axons and has a positive effect on the Schwann cells.

Ultrastructural characteristics of tensional regions in tendons from rats of different ages

The calcaneal tendon and the deep digital flexor tendon are collagen-rich structures which are adapted to resist tensile stress. Since during aging tendons undergo modifications in their mechanical properties and in collagen aggregation, an understanding of the structural changes involved is important. In this work, the structural organization of the tensile region of the calcaneal and deep difital flexor tendons was studied in male Wistar rats 30, 180 and 730 days old. Large quantities of rough endoplasmic reticulum and peripheral secretory microvesicles were observed in the calcaneal tendon of 30-day-old rats. In the case of the deep digital flexor tendon, this organelle remained well-developed up to 180 days. A marked decrease in rough endoplasmic reticulum was observed in both tendons in 730-day-old rats. Proteoglycans associated with collagen fibrils were visible in the two tendons of all age groups. The reduced amount of rough endoplasmic reticulum and secretory microvesicles may be correlated with the known lower turnover of extracellular matrix components during aging.

A biochemical histochemical analysis of the efficiency of a low ionic strength solution in extracting cartilage extracellular matrix components

The extracellular matrix of cartilage is composed of collagen, proteoglycans and non-collagenous proteins. These components may interact sufficiently strongly with each other, so that they can only be extracted using chaotropic agents such as 4 M quanidine chloride. Extraction in this normally preceded by homogenization in phosphate buffered saline (PBS) solution (0.15 NaCl, 5mM phosphate buffer, pH 7.4) followed by centrifugation to obtain a precipitate which is then extracted with guanidine chloride. In this work, the suitability of PBS alone for extracting the components of chicken xiphoid cartilage was compared with that of guanidine chloride. The stability of the matrix components obtained was also analyzed. Proteins with molecular masses of 30, 40, 52, 58 and 110 kDa were identified in the PBS extract. Small proteoglycans were detected in guanidine chloride extracts, but not in PBS extracts, suggesting that these molecules were strongly bound to other components of the matrix. The examination of cartilage sections stained with toluidine blue and Ponceau S after exposure to saline and guanidine chloride, showed that although saline did not remove substantial amounts of glycosaminoglycans it caused structural changes in the organization of the extracellular matrix. However, this effect was much less than with guanidine chloride.

Effect of magnesium chloride and guanidinum chloride on the extraction of components of extracellular matrix from chicken cartilage

In order to evaluate the effect of chaotropic agents on proteoglycan and non-collagenous proteins, chicken xiphoid cartilage was treated with guanidine-HCI and MgCl2 in different concentrations (1M to 5M), and different periods of time (12, 24, 48 and 72hr). The maximum yield of uronic acid was obtained with 3M MgCl2 (73.3 per cent). Concentrations of 4M and 5M of MgCl2 showed that much less uronic acid was removed, 55.3 per cent and 38.1 respectively. Extraction with 3M MgCl2 and 3M guanidine-HCl resulted better efficiency when performed for 48 hr. Analysis by SDS-PAGE of the extracts obtained with guanidine-HCl and MgCl, in different concentrations pointed out that most components are equally removed with the two solvents, showing that the extraction with MgCl2 is an alternative assay to remove non-collagenous proteins from extracellular matrix

Interaction of concanavalin A with sugar residues of collagen from different tissues

Particularidades topoquímicas da reaçäo de diferentes tipos de estruturas contendo colágeno, com Cancanavalina A (Con A) näo tem sido considerados até agora. A presença de disponibilidade de resíduos de glicose em moléculas de colágeno de intestino, fígado, cartilagem e tendäo säo verificados usando Con A e peroxidase de rábano silvestre (HRP). Em cortes de intestino, cartilagem e tendäo, o método usando Con A-HRP só foi significativamente positivo quando os cortes eram submetidos a um tratamento prévio com papaína sugerindo a presença de glicoproteínas e proteoglicanas da matriz extracelular (ECM), interagindo com resíduos laterais de carboidratos das moléculas de colágeno ou causando algum bloqueio estérico como ocorre em regiöes com alto estado de compactaçäo