Estimation of Postmortem Interval Based on the Third Component of Complement (C3) Cleavage

应用交叉免疫电泳技术研究了老年人和尸体血补体第三成分（C3）的自发裂解，以推断死亡时间。在不同温度下的体外C3裂解表明，在较高温度下孵育全血导致β IC（天然C3）更快地转化为β 1A（C3_c）。在尸体血液中，我们发现C3裂解百分比与pmi之间存在显著正相关。根据这些结果，可以从C3裂解率估计PMI。使用描述为dC/dt = -kC的体外C3裂解动力学，其中C是时间t时天然C3的浓度，k是一级速率常数，Arcidius方程和另一个假设死亡后体温线性下降的方程，计算C3裂解的百分比。在尸体血液中，计算的百分比和测量的百分比之间存在显著的正相关性，高达10%。我们发现，C3裂解的计算百分比之间的比较，每个可选的死后间隔和测量的百分比高达10%的尸体血液导致PMI的估计。这种方法是发展基于C3裂解（即一级反应）测定PMI的准确方法的一步。

To estimate postmortem interval(PMI), spontaneous cleavage of the third component of complement (C3) was studied in aged blood and cadaveric blood by crossed immunoelectrophoresis. C3 cleavages in vitro at different temperatures showed that the incubation of whole blood at a higher temperature led to a faster conversion of beta IC (native C3) to beta 1A (C3_c). In cadaveric blood, we found a significant positive correlation between percentage of C3 cleavage and pmi. From these results, it is possible to estimate PMI from the ratios of C3 cleavege. Using the kinetics of C3 cleavage in vitro described as dC/dt = -kC, where C is the consentration of native C3 at time t and k is a first-order rate constant, Arrhenius' equation, and another equation which assumes a linear drop of body temperature after death, the percentages of C3 cleavage were calculated. There was a significant positive correlation between the calculated percentages and the measured percentages of up to 10% in cadaveric blood. We found that the comparison between the calculated percentage of C3 cleavage for each optional postmortem interval and the measured percentage of up to 10% in cadaveric blood leads to the estimation of PMI. This approach is one step towards the development of an accurate method for determining PMI based on C3 cleavage, that is, on a first-order reaction.