Effect of epithelial debridement on human cornea proteoglycans

Corneal transparency is attributed to the regular spacing and diameter of collagen fibrils, and proteoglycans may play a role in fibrillogenesis and matrix assembly. Corneal scar tissue is opaque and this opacity is explained by decreased ultrastructural order that may be related to proteoglycan composition. Thus, the objectives of the present study were to characterize the proteoglycans synthesized by human corneal explants and to investigate the effect of mechanical epithelial debridement. Human corneas unsuitable for transplants were immersed in F-12 culture medium and maintained under tissue culture conditions. The proteoglycans synthesized in 24 h were labeled metabolically by the addition of 35S-sulfate to the medium. These compounds were extracted by 4 M GuHCl and identified by a combination of agarose gel electrophoresis, enzymatic degradation with protease and mucopolysaccharidases, and immunoblotting. Decorin was identified as the main dermatan sulfate proteoglycan and keratan sulfate proteoglycans were also prominent components. When the glycosaminoglycan side chains were analyzed, only keratan sulfate and dermatan sulfate were detected (~50 percent each). Nevertheless, when these compounds were 35S-labeled metabolically, the label in dermatan sulfate was greater than in keratan sulfate, suggesting a lower synthesis rate for keratan sulfate. 35S-Heparan sulfate also appeared. The removal of the epithelial layer caused a decrease in heparan sulfate labeling and induced the synthesis of dermatan sulfate by the stroma. The increased deposit of dermatan sulfate proteoglycans in the stroma suggests a functional relationship between epithelium and stroma that could be related to the corneal opacity that may appear after epithelial cell debridement

Production and characterization of monoclonal antibodies to shark cartilage proteoglycan

1. Two proteoglycans, PG1 and PG2, have been isolated from shark cartilage. Both are highly polydisperse and large (molecular mass: 1-10 x 10**6 Daltons) and contain chondroitin sulfate and keratan sulfate side chains, but PG2 is somewhat smaller tham PG1 and contains less keratan sulfate. 2. Monoclonal antibodies were raised against PG1. Many antibodies were obtained and one of them, MST1, was subcloned and furter characterized. This monoclonal antibody reacts with PG1 and PG2 from shark cartilage and also with aggrecan from bovine trachea cartilage. Chondroitinase AC-treated proteglycans react MST1, indicating that the antibody does not reconize chondroitin sulfate. MST1 also recognizes aggrecan from human cartilage and a proteoglycan from bovine brain (neurocan) but it does reconize proteoglycans from rat Walker tumor, fetal calf muscle and decorin from human myoma. 3. Using MST1 we were able to demonstrate that both PG1 aggregate with hyaluronic acid

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

Effect of total food deprivation on the proteoglycans of rat hyaline cartilage and bone

Hay hipótesis que sugieren que el efecto de la privación total de alimentos sobre el hueso ocurre por alteraciones en la síntesis de la matriz orgánica. Este trabajo se llevó a cabo con el propósito de caracterizar las posibles alteraciones en las propiedades de los proteoglucanos de cartílago hialino y hueso de rata como resultado de un ayuno total. Ratas macho de la cepa Wistar fueron separadas aleatoriamente y asignadas a un grupo control que comió y bebió "ad libitum" o a un grupo experimental que únicamente bebió agua. Los animales fueron pesados y sacrificados a los 4 u 8 días de iniciada la experiencia después de administrarles una dosis de 35S(-SO4-). Se aislaron los PG de los fémures y cartílagos xifoides y se determinó la captación de 35S, el patrón de distribución de los GAG, el peso molecular y densidad de los PG y el largo de las cadenas laterales. Todos los parámetros analizados disminuyeron significativamente después de 4 y 8 días mostró una disminución de la fracción correspondiente al Congroitin-4-Sulfato. Estos resultados podrían indicar una alteración en el proceso de osificación como consecuencia de las modificaciones en las propiedades de los PG que alterarían su unión con el colágeno, molécula que desempeña un papel muy importante en el mencionado proceso