以免疫染色探討觸電身亡者心肌中c-Fos的表現

Abstract

在疑似觸電死亡的案件中，不論是在相驗或法醫解剖時，若在皮膚上無明顯觸電的燒焦痕或明確之死後型態上的變化，便很難找到其他足以佐證為觸電死亡的證據。在法醫病理診斷中，外觀和顯微病理檢查的結果一直是辨別死因的黃金標準，然而為了讓死因的診斷更為精確，科學家們多年來致力於研究，期能找出協助診斷的方法。其中c-fos是一原致癌基因，它屬於初級反應基因中的一小群；其轉譯出的蛋白c-Fos，在訊息傳遞的過程中扮演重要的角色，在細胞受到刺激時，能對外在環境產生反應。過去的研究顯示，c-Fos和心肌受損有關，並且和受傷之後的修復亦有很大的相關性，曾有文獻提到c-Fos的表現和觸電死亡的動物實驗之發表，但尚無人體實際上的研究。為了更加瞭解電擊致死案件在人體之型態變化，本研究共收集了經司法解剖確定為觸電身亡之案件5件當實驗組，及非因觸電原因死亡之司法解剖案件16件當對照組，比較其在組織病理型態上的差異；並藉由免疫組織染色法，探討其中c-Fos蛋白在皮膚及心肌之表現。結果顯示，在5個觸電身亡之實驗組死者中，其心肌組織較常可見到點狀出血、心肌纖維大範圍斷裂及心肌細胞之細胞核從卵圓形變得較圓鈍形；在免疫組織染色下，所有因電擊致死的案例，其心肌組織皆可看見其心肌細胞之細胞核呈褐色，顯示有c-Fos蛋白之表現量增加；在非電擊對照組中，則沒有案例的心肌細胞之細胞核呈褐色，顯示c-Fos蛋白與細胞受到刺激後之反應和心肌的損傷有很大的關係。由初步結果可知，除了傳統的皮膚和心肌組織病理學檢查，再佐以免疫組織化學染色法的幫忙，可以促進辨別死者是否為生前觸電及其死亡原因更為精確。

It has been a puzzling forensic task to determine the cause of death as a result of electric shock in the absence of recognizable skin marks or definite postmortem morphological findings. In forensic pathology, while classical macroscopic and microscopic morphology remain core procedures to investigate deaths, a variety of subsidiary parameters has been developed and incorporated to detail that pathology. Among the candidates, c-fos, a proto-oncogene, is one of a small group of genes called primary response genes and its protein product, c-Fos, are crucial elements of signal transduction and believe to be responsible for cell response to stimulation. It has been found that c-Fos plays a significant role in myocardial lesions, and has close relation to injury repair of the molecule. Once a study had concluded that there was close relationship between c-Fos and electrocution in animal models, however, there has been no human similar experiment till now. To better characterize the morphologic changes in electrocution of human, we collected 5 victims proved to be died of electrocution as experiment group and 16 victims died of non-electrical death cases as control group. The protein, c-Fos, in all subjects were studied via immunohistochemical analysis. We compared the morphological changes between these two groups, it’s more common to see petechiae, diffuse fragmentation of the myocardium, and ‘‘Square’’ appearance in septal myocardial nuclei in the experimental group. In immunohistochemical analysis , increased c-Fos protein positive cardiomyocyte nuclei was also seen, and no c-Fos protein expression was seen in non-electrical death control group relatively. Our preliminary conclusion revealed that classical histopathology observation in epidermis and ventricular septum associates with immunohistochemical staining can give us more correct diagnosis in cause of death in electrocution.