Four peptidokeratan sulphate fractions of different Mr and degree of sulphation were cut from the pig corneal keratan sulphate distribution spectrum. After exhaustive digestion with keratanase, the fragments were separated on DEAE-Sephacel and Bio-Gel P-10 and analysed for their Mr, degree of sulphation and amino sugar and neutral sugar content. It was found that every glycosaminoglycan chain is constructed of a constant domain of non-sulphated and monosulphated disaccharide units and a variable domain of disulphated disaccharide units. Total neuraminic acid of the four peptidokeratan sulphates was recovered from their isolated linkage-region oligosaccharides. In kinetic studies, the four peptidokeratan sulphates were investigated for Mr distribution after various incubation times with keratanase. There was a continuous shift towards lower Mr and no appearance of a distinct intermediate-sized product at any degradation time. The linkage-region oligosaccharide was already being liberated after a very short incubation period. From the results of these kinetic investigations in connection with the results of neuraminic acid analyses it is suggested that there exists only one disaccharide chain per peptidokeratan sulphate molecule. A model of corneal keratan sulphate is postulated. One of the alpha-mannose residues in the linkage region is bound to an oligosaccharide consisting of a lactosamine and a terminal sialic acid. The other alpha-mannose residue is attached to the disaccharide chain. This chain contains one or two non-sulphated disaccharide units at the reducing end, followed by 10-12 monosulphated disaccharide units. The disulphated disaccharide moiety of variable length is positioned at the non-reducing end of the chain.

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In specimens taken from the posterior lip of the cervix uteri we determined the collagenase activity and the glycosaminoglycan concentration. In biopsies obtained from the lower uterine segment during cesarian section we measured cytokines (IL-8, IL-2, TNF alpha) and matrix metalloproteinases (MMP-8, MMP-9). We found that the release of collagenases is critically involved in the process of cervical dilatation. The glycosaminoglycan concentration increases during pregnancy and shows remarkable changes of the distribution patterns of the different glycosaminoglycans. The parturition is characterized by a dramatic loss of most of the glycosaminoglycans. Furthermore, the IL-8 shows a close correlation to the clinical feature of cervical ripening and is closely associated with the release of MMP-8 and MMP-9. Summarizing the process of cervical maturation and dilatation is a complex enzymatic controlled process with substantial remodelling of the cervical extracellular matrix. The cytokines IL-8 seems to play an essential role in triggering the process of cervical dilatation.

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