Navegando por Palavras-chave "corneal explants"

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    Effect of epithelial debridement on glycosaminoglycan synthesis by human corneal explants
    (Elsevier B.V., 2000-05-01) Soriano, E. S.; Campos, MSQ; Michelacci, Y. M.; Universidade Federal de São Paulo (UNIFESP)
    The purpose of the present work was to investigate the effects of mechanical epithelial debridement upon glycosaminoglycan synthesis by human corneal explants Corneal explants were maintained under tissue culture conditions for 2-72 days and the glycosaminoglycans synthesized in 24 h were metabolically labeled by addition of S-35-sulfate to the culture medium. These compounds were isolated from the tissue explants and analyzed by a combination of agarose gel electrophoresis and enzymatic degradation with specific mucopolysaccharidases. the glycosaminoglycans synthesized by isolated epithelial cells and by corneas previously submitted to epithelial cell debridement were compared to controls. Keratan sulfate (26 kDa) and dermatan sulfate (43 kDa) were the main corneal glycosaminoglycans,each one corresponding to about 50% of the total. Nevertheless, the main S-35-labeled glycosaminoglycan was S-35-dermatan sulfate (73%), with smaller amounts of S-35-keratan sulfate (15%) and S-35-heparan sulfate (12%), suggesting a lower synthesis rate for keratan sulfate. the main glycosaminoglycan synthesized by isolated epithelial cells was heparan sulfate. the removal of epithelial layer caused a decrease in heparan sulfate labeling and induced the synthesis of dermatan sulfate by stromal cells. This increased synthesis of dermatan sulfate suggest a relationship between epithelium and stroma and could be related to the corneal opacity that may appear after epithelial cell debridement. (C) 2000 Elsevier Science B.V. All rights reserved.
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    Effect of epithelial debridement on human cornea proteoglycans
    (Associação Brasileira de Divulgação Científica, 2001-03-01) Soriano, Eduardo Sone [UNIFESP]; Campos, Mauro Silveira de Queiroz [UNIFESP]; Aguiar, Jair Adriano Kopke [UNIFESP]; Michelacci, Yara Maria [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    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% 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.