Faculty of Psychology, University of Vienna, Liebiggasse 5, 1010, Vienna, Austria.
Faculty of Psychology, University of Vienna, Liebiggasse 5, 1010, Vienna, Austria.
Psychoneuroendocrinology. 2020 Nov;121:104847. doi: 10.1016/j.psyneuen.2020.104847. Epub 2020 Aug 27.
For the measurement of salivary alpha-amylase (sAA) activity, saliva samples first have to be diluted. There is some evidence for instability, that is, a decline of sAA activity in diluted samples. It is not clear which factors during dilution may contribute to this phenomenon and how quickly this decline of sAA activity occurs. Several experiments were conducted to investigate whether and how the material of the container (polystyrene (PS), polypropylene (PP), glass; experiment 1) and the diluent (saline (NaCl) solution, phosphate buffer saline (PBS), ultra-pure water; experiment 2) may affect sAA stability in diluted samples over a broad time window of up to 5 h. To study the velocity of the phenomenon in a fine-grained temporal resolution, sAA activity during the dilution process was studied (experiment 3). The results suggest that the (in)stability of sAA activity in diluted samples is determined by the interaction of material, diluent, and time. The sAA activity was relatively stable if saliva samples were diluted with a NaCl solution or PBS in glass tubes. However, sAA activity in diluted samples decreased in plastic containers (PS, PP), or if ultra-pure water was used as the diluent. There was a clear time effect on this decline. However, the decline appears to require some time to evolve and may not occur immediately during the dilution process. To conclude, the dilution of saliva samples should preferably be conducted with NaCl solution or PBS in glass containers. If glass containers are not available, PS and PP containers can be used if the dilution is processed quickly (within 25 min) and the measurement is initiated immediately upon dilution.
为了测量唾液α-淀粉酶（sAA）的活性，首先需要对唾液样本进行稀释。有一些证据表明 sAA 的活性不稳定，即稀释后的样本中 sAA 的活性会下降。目前尚不清楚在稀释过程中哪些因素可能导致这种现象，以及 sAA 活性的下降速度有多快。进行了几项实验来研究容器的材料（聚苯乙烯（PS）、聚丙烯（PP）、玻璃；实验 1）和稀释剂（生理盐水（NaCl）溶液、磷酸盐缓冲盐水（PBS）、超纯水；实验 2）是否以及如何在长达 5 小时的广泛时间窗口内影响稀释样本中的 sAA 稳定性。为了在更精细的时间分辨率下研究该现象的速度，研究了稀释过程中 sAA 活性的变化（实验 3）。结果表明，稀释样本中 sAA 活性的（不）稳定性取决于材料、稀释剂和时间的相互作用。如果将唾液样本用 NaCl 溶液或 PBS 稀释在玻璃管中，则 sAA 活性相对稳定。然而，如果使用超纯水作为稀释剂，则 sAA 活性会在塑料容器（PS、PP）中下降。在这种下降过程中存在明显的时间效应。然而，这种下降似乎需要一些时间才能显现，并且可能不会在稀释过程中立即发生。总之，最好在玻璃容器中用 NaCl 溶液或 PBS 稀释唾液样本。如果没有玻璃容器，也可以使用 PS 和 PP 容器，但稀释过程需要快速（在 25 分钟内）进行，并且在稀释后立即开始测量。
