Paltiel Liv, Rønningen Kjersti S, Meltzer Helle M, Baker Susan V, Hoppin Jane A
Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.
Cell Preserv Technol. 2008 Sep 1;6(3):223-230. doi: 10.1089/cpt.2008.0012.
In many cohort studies, biological specimens are being stored without specific plans for analyses. In the Norwegian Mother and Child Cohort Study biological specimens (DNA, plasma, and whole blood) are stored on 96-well plates and as a result may undergo multiple freeze-thaw cycles. METHODS: To explore the impact of multiple freeze-thaw cycles on chemical constituents, we conducted a quality control study using pooled EDTA-plasma. Over a two-year period, samples stored at -80 degrees C were subjected up to 100 freeze-thaw cycles. Specimens were analyzed in triplicate for sodium, cholesterol, triglycerides, vitamin E, aspartate aminotransferase (AST), and free fatty acids. We assessed the percent change of analyte concentration from the values for the first freeze-thaw cycle, because this is the baseline for all stored specimens. RESULTS: With the exception of free fatty acids, there was little change over the first 10 freeze-thaw cycles. A majority of analytes showed no significant changes until 30 freeze-thaw cycles. After 30 freeze-thaw cycles, the largest percent change was observed for free fatty acids (+32%), AST (+21%), and triglycerides (-19%). CONCLUSIONS: Human plasma can go through several freeze-thaw cycles before analysis without influencing sample integrity for the selected analytes.
在许多队列研究中，生物标本的储存没有具体的分析计划。在挪威母婴队列研究中，生物标本（DNA、血浆和全血）储存在96孔板中，因此可能会经历多次冻融循环。方法：为了探究多次冻融循环对化学成分的影响，我们使用混合乙二胺四乙酸血浆进行了一项质量控制研究。在两年的时间里，储存在-80℃的样本经历了多达100次冻融循环。对标本的钠、胆固醇、甘油三酯、维生素E、天冬氨酸转氨酶（AST）和游离脂肪酸进行了三次重复分析。我们评估了分析物浓度相对于第一个冻融循环时的值的变化百分比，因为这是所有储存标本的基线。结果：除游离脂肪酸外，在前10次冻融循环中变化很小。大多数分析物在30次冻融循环之前没有显著变化。30次冻融循环后，游离脂肪酸（+32%）、AST（+21%）和甘油三酯（-19%）的变化百分比最大。结论：人体血浆在分析前可以经历多次冻融循环，而不会影响所选分析物的样本完整性。
