Squitti Rosanna, Siotto Mariacristina, Cassetta Emanuele, El Idrissi Imane Ghafir, Colabufo Nicola A
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Clin Chem Lab Med. 2017 Aug 28;55(9):1360-1367. doi: 10.1515/cclm-2016-0843.
Meta-analyses indicated the breakdown of copper homeostasis in the sporadic form of Alzheimer's disease (AD), comprising copper decreases within the brain and copper increases in the blood and the pool not bound to ceruloplasmin (non-Cp Cu, also known in the literature as "free" copper). The calculated non-Cp Cu (Walshe's) index has many limitations.
A direct fluorescent method for non-Cp Cu detection has been developed and data are presented herein. The study included samples from 147 healthy subjects, 36 stable mild cognitive impairment (MCI) and 89 AD patients, who were tested for non-Cp Cu through the direct method, total serum copper, ceruloplasmin concentration and o-dianisidine ceruloplasmin activity. The indirect non-Cp Cu Walshe's index was also calculated.
The direct method was linear (0.9-5.9 μM), precise (within-laboratory coefficient variation of 9.7% for low and 7.1% for high measurements), and had a good recovery. A reference interval (0-1.9 μM) was determined parametrically in 147 healthy controls (27-84 years old). The variation of non-Cp Cu was evaluated according to age and sex. Non-Cp Cu was 1.5 times higher in AD patients (regarding the upper value of the reference interval) than in healthy controls. Healthy, MCI and AD subjects were differentiated through the direct non-Cp Cu method [areas under the curve (AUC)=0.755]. Considering a 95% specificity and a 1.91 μmol/L cut-off, the sensitivity was 48.3% (confidence interval 95%: 38%-58%). The likelihood ratio (LR) was 9.94 for positive test results (LR+) and 0.54 for negative test result (LR-).
The direct fluorescent test reliably and accurately measures non-Cp Cu, thereby determining the probability of having AD.
荟萃分析表明，散发性阿尔茨海默病（AD）存在铜稳态失衡，包括脑内铜含量降低，血液及未与铜蓝蛋白结合的铜池（非铜蓝蛋白结合铜，文献中也称为“游离”铜）中铜含量升高。计算得出的非铜蓝蛋白结合铜（瓦尔什氏）指数存在诸多局限性。
已开发出一种用于检测非铜蓝蛋白结合铜的直接荧光法，并在此展示相关数据。该研究纳入了147名健康受试者、36名稳定的轻度认知障碍（MCI）患者和89名AD患者的样本，通过直接法检测非铜蓝蛋白结合铜、血清总铜、铜蓝蛋白浓度及邻联茴香胺铜蓝蛋白活性。还计算了间接的非铜蓝蛋白结合铜瓦尔什氏指数。
直接法呈线性（0.9 - 5.9 μM），精密度高（低测量值的实验室内变异系数为9.7%，高测量值为7.1%），回收率良好。在147名健康对照者（年龄27 - 84岁）中通过参数法确定了参考区间（0 - 1.9 μM）。根据年龄和性别评估了非铜蓝蛋白结合铜的变化。AD患者的非铜蓝蛋白结合铜（相对于参考区间上限值）比健康对照者高1.5倍。通过直接非铜蓝蛋白结合铜法可区分健康、MCI和AD受试者[曲线下面积（AUC）=0.755]。考虑到95%的特异性和1.91 μmol/L的截断值，灵敏度为48.3%（95%置信区间：38% - 58%）。阳性检测结果的似然比（LR）为9.94（LR +），阴性检测结果的似然比为0.54（LR -）。
直接荧光检测能可靠且准确地测量非铜蓝蛋白结合铜，从而确定患AD的概率。
