Objective Glypican4 is an interesting new adipokine, which seems to play an important role in developmental processes and is potentially associated with metabolic changes in obesity and type 2 diabetes mellitus. Currently, only a few studies examined glypican4 in human blood, mainly in adults. Design, Patients and Measurements The aim of our study was to investigate glypican4 serum levels in lean, overweight, and obese children and adolescents, to unravel a possible association between glypican4 serum levels and parameters of obesity and insulin resistance. In order to determine a suitable method for investigating glypican4 serum levels, we validated two commercially available human glypican4 ELISA kits, using serum and plasma samples of an obese, insulin-resistant patient, and a healthy control subject, a human recombinant glypican4 protein fragment and glypican4-overexpressing cell lysate. Results Using ELISA kit #1 we were not able to detect values above background level, apart from standard curve values. ELISA kit #2 initially seemed suitable to measure glypican4, but further validation experiments showed non-linearity of serial dilutions, no recognition of a human recombinant glypican4 protein fragment and non-linearity in the recovery of glypican4-overexpressing cell lysate. In addition, there was a considerable decrease (approx. 68%) of measured values between two experiments, performed at different time points with aliquots of the same serum sample. Contrary to that, further experiments found sample stability not to be compromised. Conclusions Extensive evaluation of the performance of two commercially available ELISA kits led to the conclusion that none of them is applicable for the measurement of glypican4 in human blood samples.

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市售的 Glypican4 ELISA 试剂盒的可靠性如何？

目的 Glypican4 是一种有趣的新型脂肪因子，似乎在发育过程中发挥重要作用，并可能与肥胖和 2 型糖尿病的代谢变化有关。目前，只有少数研究检测了人体血液中的 glypican4，主要是在成人中。设计、患者和测量 我们研究的目的是调查瘦、超重和肥胖儿童和青少年的血清 glypican4 水平，以揭示血清 glypican4 水平与肥胖和胰岛素抵抗参数之间的可能关联。为了确定研究 glypican4 血清水平的合适方法，我们使用肥胖、胰岛素抵抗患者和健康对照受试者的血清和血浆样本验证了两种市售的人类 glypican4 ELISA 试剂盒，人重组glypican4蛋白片段和glypican4过表达细胞裂解物。结果 使用 ELISA 试剂盒 #1，除了标准曲线值外，我们无法检测到高于背景水平的值。ELISA 试剂盒 #2 最初似乎适用于测量 glypican4，但进一步的验证实验显示连续稀释的非线性、无法识别人重组 glypican4 蛋白片段以及回收过表达 glypican4 的细胞裂解物的非线性。此外，在不同时间点使用相同血清样品的等分试样进行的两次实验之间，测量值显着下降（约 68%）。与此相反，进一步的实验发现样品稳定性不会受到影响。