肌腱内胶原纤维半径的均匀空间分布意味着单个纤维处pC-collagen的局部活化
Uniform spatial distribution of collagen fibril radii within tendon implies local activation of pC-collagen at individual fibrils
摘要：
胶原原纤维的横截面半径没有显示出系统的变化之间的内部和周边的原纤维束，表明一个有效的恒定速率的胶原蛋白掺入到整个束的原纤维。这种空间上均匀的掺入限制了胶原前体从纤维束边界处的来源向生长中的原纤维处的汇的细胞外扩散。与粗粒度的扩散方程，我们确定严格的界限，使用从公布的肌腱发展的实验测量提取的参数。由于出生后缺乏新的原纤维形成，我们进一步要求扩散前体的浓度保持低于原纤维成核的临界浓度。我们发现，扩散结合，这需要更大的浓度，以确保均匀的原纤维半径，和缺乏成核，这需要较低的浓度的组合，是只有轻微一致的完全处理的胶原蛋白使用保守的边界。更现实的界限可能不会留下一致的浓度。因此，我们建议，未加工的PC-胶原蛋白扩散从束周边，然后由本地C-蛋白酶活性和随后的胶原蛋白掺入在每个原纤维。我们认为，C-蛋白酶是本地化的束内，在原纤维表面，在径向原纤维生长。与完全加工的胶原相比，更大的PC-胶原的临界浓度提供了均匀原纤维半径与原纤维生长期间缺乏原纤维成核之间的广泛一致性。
英文摘要：
Collagen fibril cross-sectional radii show no systematic variation between the interior and the periphery of fibril bundles, indicating an effectively constant rate of collagen incorporation into fibrils throughout the bundle. Such spatially homogeneous incorporation constrains the extracellular diffusion of collagen precursors from sources at the bundle boundary to sinks at the growing fibrils. With a coarse-grained diffusion equation we determine stringent bounds, using parameters extracted from published experimental measurements of tendon development. From the lack of new fibril formation after birth, we further require that the concentration of diffusing precursors stays below the critical concentration for fibril nucleation. We find that the combination of the diffusive bound, which requires larger concentrations to ensure homogeneous fibril radii, and lack of nucleation, which requires lower concentrations, is only marginally consistent with fully-processed collagen using conservative bounds. More realistic bounds may leave no consistent concentrations. Therefore, we propose that unprocessed pC-collagen diffuses from the bundle periphery followed by local C-proteinase activity and subsequent collagen incorporation at each fibril. We suggest that C-proteinase is localized within bundles, at fibril surfaces, during radial fibrillar growth. The much greater critical concentration of pC-collagen, as compared to fully-processed collagen, then provides broad consistency between homogeneous fibril radii and the lack of fibril nucleation during fibril growth.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
