Hall M L, Krawczak D A, Simha N K, Lewis J L
Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN 55455, USA.
Osteoarthritis Cartilage. 2009 May;17(5):655-61. doi: 10.1016/j.joca.2008.10.010. Epub 2008 Oct 29.
This paper examines the hypothesis that the dermatan sulfate (DS) chain on decorin is a load carrying element in cartilage and that its damage or removal will alter the material properties.
To test this hypothesis, indentation and tensile testing of cartilage from bovine patella were performed before and after digestion with chondroitinase B (cB). Removal of significant amounts of DS by cB digestion was verified by Western blot analysis of proteoglycans extracted from whole and sectioned specimens. Specimens (control and treated) were subjected to a series of step-hold displacements. Elastic modulus during the step rise (rapid modulus) and at equilibrium (equilibrium modulus), and the relaxation function during each step was measured for test (cB and buffer) and control (buffer alone) conditions.
cB had no effect on any of the viscoelastic mechanical properties measured, either in indentation or tension.
Removing or damaging approximately 50% of the DS had no effect on the mechanical properties, strongly suggesting that DS either carries very low load or no load.
本文检验了以下假设，即核心蛋白聚糖上的硫酸皮肤素（DS）链是软骨中的一个承载元件，其损伤或去除会改变材料特性。
为验证该假设，在用软骨素酶B（cB）消化前后，对牛髌骨软骨进行了压痕和拉伸测试。通过对从完整和切片标本中提取的蛋白聚糖进行蛋白质印迹分析，证实了cB消化可去除大量DS。对标本（对照和处理组）施加一系列逐步保持位移。测量了测试（cB和缓冲液）和对照（仅缓冲液）条件下，阶跃上升期间（快速模量）和平衡时（平衡模量）的弹性模量，以及每个步骤中的松弛函数。
无论是压痕测试还是拉伸测试，cB对所测量的任何粘弹性力学性能均无影响。
去除或损伤约50%的DS对力学性能没有影响，这强烈表明DS要么承载的负荷极低，要么不承载负荷。
