Degraded collagen

Table 9.5. Re-estimation of in vivo 8 C from experimentally degraded collagen. Correction failed, nd = not determined.

Collagenase is also produced by Cl. perfringens and this degrades collagen, which is the major protein offibrous tissue. Its destruction promotes the spread of infection in tissues. 

In confrasf fo erosive lesions formed at pH 5.0 and pH 5.5, not only the amount of collagen that was degraded (fig. 6) buf also fhe rafio of degraded collagen to calcium loss over ten days were much higher in lesions formed af pH 4.5 (8.7 1.2 pg/pmol) than in lesions formed at pH 5.0 (3.8 2.7 pg/pmol). 

The ratios of degraded collagen to calcium loss for specimens demineralized at pH 5.0 and pH 5.5 and treated with collagenase throughout the experiment were 27.7 1.4 pg/pmol and 24.5 2.4 pg/pmol respectively. These values were close to the ratio found by Klont and Ten Cate (1991) for completely demineralized dentin (23.3 pg/pmol). 

Klont and Ten Cate (1991) determined the ratio of collagen to calcium for dentin, which is consistent with the ratio of degraded collagen to calcium loss in advanced erosive lesions, while this ratio was lower in incipient lesions. In the initial phase of lesion formation, a relatively large part of the collagen is apparently insusceptible to the action of collagenase. 

The collagenase treatment of specimens demineralized in HLac-MHDP at pH 5.0 did not cause visible differences between the matrix of collagenase-treated lesions and that of buffer-treated lesions. This is consistent with the fact that the ratio of degraded collagen to calcium loss was lower for collagenase-treated lesions demineralized at pH 5.0 than for lesions demineralized at pH 4.5. 

Figure 3.4 Factors affecting foreign body reaction and potential points of intervention at the level of the myofibroblast (1) inhibit synthesis or release of TGF-P (2) block stimulation by TGF-P of its membrane receptors on the activated fibroblast (3) inhibit the Smad proteins, which transfer the TGF-P effect to the nucleus (4) inhibit transcription of procollagen mRNA (5) inhibit translation of the message to form procollagen (6) inhibit prolyl-4-hydroxylase, which creates hydroxyproline and facilitates helix formation (7) inhibit lysyl oxidase, which cross-links the collagen (8) enhance the function of MMPs, which degrade collagen, or inhibit TIMPs, which degrade MMPs.

Rabbit connective tissues secrete at least three distinct neutral proteinases, capable of degrading collagen, gelatin, and proteoglycans, respectively. A modified procedure for the preparation of Smith-degraded proteoglycans has been reported. The product has been used in the assay of D-xylosyltransferase in cartilage extracts. 

Collagen Collagen is the major fibrous protein making up bone and skin. Degraded collagen is the major component of glue and gelatine. 

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