ABSTRACT The distribution pattern of proteoglycans in the extracellular matrix of M. semimembranosus from young bulls was studied in frozen tissue sections by immunohistochemical methods. The small proteoglycan, decorin, was found widely distributed in both perimysial and endomysial layers. Another member of the same proteoglycan family, fibromodulin, could only be seen associated with the fiber bundles of the perimysium. Furthermore, aggrecan‐like proteoglycans were detected mainly in the perimysium with a different staining pattern than decorin and fibromodulin. A basement membrane type heparan sulfate proteoglycan was present only in the endomysium, with particularly strong staining in the junctions of endomysial layers between neighboring myofibers. The distribution of proteoglycans in the peri‐ and endomysium of striated muscle tissue influences the organization of the collagen fibrils and, therefore, the texture and strength of muscle matrix. Proteoglycans should be considered a component of muscle influencing meat tenderness.
Selective periodate oxidation of unsubstituted l-iduronic acid residues in copolymeric dermatan sulphate chains was followed by reduction-hydrolysis or alkaline elimination. By this procedure the glucuronic acid-containing periods were isolated in oligosaccharide form; general formula: [Formula: see text] Further degradation of these oligosaccharides with chondroitinase-AC yielded three types of products: (a) sulphated trisaccharide containing an unsaturated uronosyl moiety in the non-reducing terminal and a C(4) fragment in the reducing terminal, DeltaUA-GalNAc-(-SO(4))-R; (b) monosulphated, unsaturated disaccharide, DeltaUA-GalNAc-SO(4) when n is greater than or equal to 2; and (c) N-acetylgalactosamine with or without sulphate. Oligosaccharides containing a single glucuronic acid residue (n=1) comprised more than half of the glucuronic acid-containing oligosaccharides. The terminal N-acetylgalactosamine moiety of the shortest oligosaccharide was largely 4-sulphated, whereas higher oligosaccharides primarily contained 6-sulphated or unsulphated hexosamine moieties in the same position. Moreover, IdUA-SO(4)-containing oligosaccharides were encountered. These oligosaccharides were resistant to the action of chondroitinase-ABC.
Here we have examined the enzymes cyclooxygenase (COX)-2 and 15-hydroxyprostaglandin dehydrogenase (15-OH PGDH) in pregnant human cervix. In biopsies taken transvaginally after preterm and term elective cesarean sections and vaginal deliveries, the levels of mRNA coding for COX-2 and 15-OH PGDH were assessed by Northern blotting. The cellular localization of the COX-2 and 15-OH PGDH proteins was determined by immunohistochemical analysis. COX-2 and 15-OH PGDH mRNAs were expressed at detectable levels in the cervical biopsies from all four groups of subjects. At cesarean sections (unripe cervix), the level of 15-OH PGDH mRNA was significantly higher than the level in the ripe cervix at the time of partus, irrespective of the gestational length. In contrast, the level of COX-2 mRNA was similar in all subjects. Immunoreactivity of COX-2 and 15-OH PGDH was expressed by activated fibroblasts. The present investigation documents the expression and cellular localization of COX-2 and 15-OH PGDH in the preterm and term pregnant human cervix. This observation indicates that both preterm and term cervical ripening is associated with decreased degradation of prostaglandins.
