Yavorskyy Alexander, Hernandez-Santana Aaron, Shortt Brian, McCarthy Geraldine, McMahon Gillian
Bioanalytical Chemistry & Diagnostics Group, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland. alexander.yavorskyy@ dcu.ie
Bioanalysis. 2010 Feb;2(2):189-95. doi: 10.4155/bio.09.163.
Microscopic inorganic crystals are commonly observed in the synovial fluid of patients suffering from arthritic diseases. Basic calcium phosphate (BCP) crystals are known to occur quite commonly in the joint fluid of osteoarthritis (OA) patients and are insoluble at physiological pH. Current analysis of patient synovial fluid depends on light microscopy and staining with Alizarin Red-S. Both methods cannot identify crystals < 1µm in size and are highly subjective. This article investigates the use of o-cresolphthalein complexone (OCP), a colorimetric reagent, to quantify calcium from crystals isolated from synovial fluid samples as a means of identifying the presence of BCP and, hence, improving the diagnosis of OA.
Inorganic crystals were isolated following degradation of the biological sample matrix with hyaluronidase. 1-M HNO(3) was used for crystal dissociation into ions and the colorimetric response of OCP to calcium was measured in a basic environment of 2-amino-2-methyl-1-propanol. The average calcium content in OA patient samples was up to 40% higher than in rheumatoid arthritis (RA) patient samples. RA samples were used as a comparison, because they are generally accepted to be crystal free. Within the OA group, higher levels of calcium were detected in three out of 12 synovial fluid samples, which correlated with a significantly greater number of BCP crystals detected during microscopic examination.
A simple method based on colorimetry for measurement of calcium content and semiquantification of BCP crystals in synovial fluid samples has been described. Sample pretreatment following addition of hyaluronidase proved to be effective in reducing viscosity and aiding the dissociation of BCP crystals in synovial fluid samples.
在患有关节炎疾病的患者滑液中通常可观察到微观无机晶体。已知碱性磷酸钙（BCP）晶体在骨关节炎（OA）患者的关节液中相当常见，且在生理pH值下不溶。目前对患者滑液的分析依赖于光学显微镜检查和茜素红S染色。这两种方法都无法识别尺寸小于1μm的晶体，且主观性很强。本文研究使用邻甲酚酞络合剂（OCP），一种比色试剂，来定量从滑液样本中分离出的晶体中的钙，以此作为识别BCP存在的一种手段，从而改善OA的诊断。
用透明质酸酶降解生物样本基质后分离出无机晶体。使用1 - M硝酸将晶体解离成离子，并在2 - 氨基 - 2 - 甲基 - 1 - 丙醇的碱性环境中测量OCP对钙的比色响应。OA患者样本中的平均钙含量比类风湿关节炎（RA）患者样本高多达40%。使用RA样本作为对照，因为一般认为它们不含晶体。在OA组中，12个滑液样本中有3个检测到较高水平的钙，这与显微镜检查期间检测到的BCP晶体数量显著更多相关。
本文描述了一种基于比色法测量滑液样本中钙含量和对BCP晶体进行半定量的简单方法。添加透明质酸酶后的样本预处理被证明在降低粘度和帮助滑液样本中BCP晶体解离方面是有效的。
