Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

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

Farmacocinética da associação de glucosamina e sulfato de condroitina em humanos sadios do sexo masculino / Pharmacokinetic profile of glucosamine and chondroitin sulfate association in healthy male individuals

A osteoartrose é uma doença crônica das articulações que, uma vez instalada, leva seus portadores a uma incapacidade funcional progressiva. Como os proteocondroitins sulfato são os maiores constituintes das cartilagens, espera-se que com a ingestão de glucosamina e condroitina haja uma melhora das condições biológicas desse tecido. Uma vez que não temos conhecimento de estudo da farmacocinética da administração oral dessa associação em seres humanos, o objetivo deste trabalho foi avaliá-la utilizando a associação entre o sulfato de glucosamina (SG) e o sulfato de condroitina (SC) administrada a dois grupos de doze voluntários sadios do sexo masculino (grupo I uma cápsula de (500 mg SG; 400 mg SC) e grupo II quatro cápsulas). Amostras de sangue foram retiradas a intervalos de tempo pré-definidos até 48 horas pós-dose. O SG e o SC foram dosados no plasma pelo método de DMMB (azul de 1,9,dimetildimetileno). A concentração máxima foi atingida em 2 horas (média ±SE; 0,893±0,093 'g/mL, grupo I e 2,222±0,313 'g/mL, grupo II). As áreas sob a curva até 48 horas foram de 10,803±0,965 'g-hr/mL e 38,776±2,981 'g-hr/mL, respectivamente para os grupos I e II. Os dois grupos apresentaram um segundo pico após 18 horas, indicando circulação êntero-hepática. Os nossos resultados indicam que essa associação é absorvida por via oral por mecanismo saturável, o que pode facilitar o seu uso em tratamentos clínicos.

Osteoartrosis y diagnóstico en ortodoncia / osteoarthritis and diagnosis in orthodontics

La osteoartrosis es un estado patológico en el cual hay cambios degenerativos en el fibrocartílago articular, seguido de un proceso de remodelamiento del hueso subyacente. El presente artículo tiene como objetivo relacionar la osteoartrosis en la articulación témporo-mandibular (ATM) con la inestabilidad oclusal, sugiriendo que estas alteraciones en la forma y tamaño de las estructuras óseas en la ATM ocasionan cambios en la oclusión. Se llevó a cabo un estudio retrospectivo de 11 pacientes quienes se presentaron a la consulta con signos y síntomas de osteoartrosis y cambios progresivos en la oclusión (mordida abierta y aumento del overjet

Extracellular matrix molecules play diverse roles in the growth and guidance of central nervous system axons

Axon growth and guidance represent complex biological processes in which probably intervene diverse sets of molecular cues that allow for the appropriate wiring of the central nervous system (CNS). The extracellular matrix (ECM) represents a major contributor of molecular signals either diffusible or membrane-bound that may regulate different stages of neural development. Some of the brain ECM molecules form tridimensional structures (tunnels and boundaries) that appear during time- and space-regulated events, possibly playing relevant roles in the control of axon elongation and pathfinding. This short review focuses mainly on the recognized roles played by proteoglycans, laminin, fibronectin and tenascin in axonal development during ontogenesis

Proteoglycans in skeletal muscle

1. Proteoglycans are macromolecules composed of a protein and one or mor chains of sulfated carbohydrates, the glycosaminoglycans. Proteoglycans are found on the cell surface and in the extracellular matrix participating in the cell-cell-extracellular matrizx interaction. In this review I present the information accumulated in the past years regarding the presence, characteristics, localization, control of expression and alteration in some pathological states of skeletal muscle proteoglycans. 2. This review presents and discusses current information in this area and some projections for the future in four sections: first, the proteoglycans present in embryonic cells and cell lines from skeletal muscle. Second, the presence of proteoglycans in adult skeletal muscles. Third, the regulation of the expression of skeletal muscle proteoglycans, and fourth, skeletal muscle proteoglycans in pathological conditions

Detection of a small proteoglycan present in xiphoid cartilage regions submitted to different biomechanical forces

1. The effect of biomechanical forces on larges proteglycans and collagen of cartilage has deserved intensive study, enhacing the importance of these molecules to support a better distribution of compressive forces especially in articular cartilage. In the present study, other extracellular matrix components, non-collagenous proteins and small proteglycans, have been evaluated in terms of biomechanical tension. 2. Different parts of chicken xiphoid cartilage, lateral (R and L) and central (C) portions, which bear different biomechanical tensions, were analyzed. DEAE-cellulose chromatography profiles were similar for R and L portions. SDS-PAGE analyses revealed proteins of 29, 60 and 70 KDa for R and L. The 20-and 70-KDa proteins were not detected in the C portion while the 60-KDaprotein was presented at a high level. 3. The differences found between lateral (R and L) and central portions of the xiphoid cartilage may be related to the struycture of the cartilage which bears higher tension forces than the lateral parts