Dynamic aspects of collagen biology. II. Degradation and metabolism

Influence of proximal colostomy on the healing of a left colon anastomosis: an experimental study in the rat

The healing of an experimental left colon anastomosis protected by a proximal diverting colostomy was studied in the rat. Collagen synthesis in the anastomotic area was measured by incorporation of [3H]proline. With a defunctioning proximal colostomy, the synthesis and accumulation of collagen in the anastomosis was diminished, and the anastomotic strength development delayed and reduced. The development of anastomotic strength seems to proceed according to the level of strain from intraluminal bulk. As the healing of the anastomosis protected by a diverting colostomy was uncomplicated, these findings should not contra-indicate the use of diverting colostomy.

Development of topical BAPN delivery system for acute spinal cord injury in dogs

Topical sustained release of various medications by a subdurally implantable device at the site of spinal cord injury is considered advantageous in the treatment of early symptoms of tissue damage. A typical case is the interference with collagenous scar by beta-aminopropionitrile, inhibiting collagen polymerization. Four materials, silicone, polyethylene, polytetrafluoroethylene (PTFE), and polyacrylonitrile-based hydrogel were evaluated for biocompatibility in subcutaneous implantations. The hydrogel, the least reactive, was then compared with silicone sheets as subcural implants. The histology favored the hydrogel as the most inert material, which was then used for the construction of soft, pliable pouches, releasing the drug through the hydrated wall at a rate controlled by an osmotic pump.

The effect of relative bowel rest on collagen metabolism and suture holding capacity in the colonic wall. Studies in the rat

In a previous experimental study it was shown that bowel rest with low residue diet led to a reduction of the non-collagenous substances in the intact, unoperated colon, while the collagen content remained unchanged. In the cecum, both the collagen content and the non-collagenous substances were markedly increased. In the present investigation the effect of relative bowel rest on collagen synthesis in the colonic wall was studied. Further, a possible influence on mechanical properties was evaluated. It was found out that bowel rest led to a marked decrease of collagen and protein synthesis in the colon. In the cecum, there was an unchanged collagen synthesis but an increased protein synthesis. It can be deduced that lysis of collagen is decreased in all parts of the colon. The depression of collagen turnover in the colonic wall was not accompanied by measurable changes in mechanical strength. It remains to be studied whether the observed changes in collagen metabolism do affect colonic healing.

Endogenous activation of latent collagenase by rheumatoid synovial cells. Evidence for a role of plasminogen activator

To elucidate the mechanism of synovial damage in rheumatoid arthritis, we studied the activation of latent collagenases released from adherent rheumatoid synovial cells in culture. Latent enzyme was not complexed with alpha2 macroglobulin, the prinicpal proteinase inhibitor in serum, and could be activated by trypsin in the presence of alpha2 macroglobulin if sufficient proteinase was added to saturate inhibitor. Latent collagenase bound half as effectively to collagen fibrils as active enzyme. Plasmin was a threefold better activator of latent enzyme than trypsin and could be generated by addition of plasminogen to synovial-cell cultures. Production of both collagenase and plasminogen activator was inhibited by dexamethasone (10(-9) M). These studies emphasize in importance of control of activation in regulation collagenase activity, It is likely that rheumatoid synovium produces both latent collagenase and plasminogen activator; plasmin is activated from its zymogen, plasminogen, present in inflamed tissues, and in turn activates collagenase.