Evans R W, Sankey S S, Hauth B A, Sutton-Tyrrell K, Kamboh M I, Kuller L H
Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pennsylvania 15261, USA.
Lipids. 1996 Nov;31(11):1197-203. doi: 10.1007/BF02524295.
This study evaluated the effect of storage on the quantitation of lipoprotein (Lp)(a) in 25 serum samples. Aliquots of serum were stored for up to three years at either -20 degrees C or -70 degrees C and Lp(a) subsequently analyzed using an enzyme-linked immunosorbent assay kit. Concentrations of Lp(a) declined during storage, and the temperatures employed elicited significantly different (P < 0.05) values within 12 mon which further diverged during three years of storage. Compared to baseline values, significant decreases (P < 0.05) in Lp(a) levels were evident after six months of storage at -20 degrees C with apparent losses (geometric mean) reaching 36.9% (95% confidence interval: 30.9%, 42.9%) after three years. Similarly, significantly lower (P < 0.05) Lp(a) values were recorded after six months of storage at -70 degrees C and at three years the decrease (geometric mean) was 19.1% (95% confidence interval: 14.3%, 24.0%). The losses, after three years, in terms of the arithmetic mean were 53.5 and 26.2% at -20 and -70 degrees C, respectively. Phenotype analysis suggested that large isoforms are more susceptible to degradation than smaller moieties. This may be related to the observation that apparent losses are reduced in samples containing over 8 mg/dL Lp(a). Nevertheless, Lp(a) levels in stored samples retained a strong correlation with the baseline values. These results must be considered specific for the storage conditions and analytical procedures employed.
本研究评估了储存对25份血清样本中脂蛋白（Lp）（a）定量的影响。将血清等分试样在-20℃或-70℃下储存长达三年，随后使用酶联免疫吸附测定试剂盒分析Lp（a）。Lp（a）的浓度在储存期间下降，并且在12个月内所采用的温度引发了显著不同（P<0.05）的值，在三年的储存期间进一步分化。与基线值相比，在-20℃储存六个月后，Lp（a）水平明显下降（P<0.05），三年后表观损失（几何平均值）达到36.9%（95%置信区间：30.9%，42.9%）。同样，在-70℃储存六个月后记录到显著较低（P<0.05）的Lp（a）值，三年后下降（几何平均值）为19.1%（95%置信区间：14.3%，24.0%）。三年后，在-20℃和-70℃下，按算术平均值计算的损失分别为53.5%和26.2%。表型分析表明，大异构体比小部分更容易降解。这可能与以下观察结果有关：在含有超过8mg/dL Lp（a）的样本中，表观损失减少。然而，储存样本中的Lp（a）水平与基线值保持着很强的相关性。这些结果必须被认为是特定于所采用的储存条件和分析程序的。
