DNA定量技术在死亡时间推断中的研究进展

死亡时间推断是法医病理学研究的热点及难点之一.随着分子生物学技术的发展,DNA的定量已广泛应用于死亡时间推断的研究.本文主要对机体死后不同组织和器官中DNA含量随时间的降解情况,以及单细胞凝胶电泳、Feulgen染色图像分析技术、流式细胞仪等近年来新的DNA定量技术应用于死亡时间推断研究中的进展进行了综述.     

离体人胸骨骨髓DNA降解与腐败尸体死亡时间推断的初步研究

目的研究死后胸骨骨髓DNA的降解与较长死后间隔时间(PMI)的关系。方法采用改良Feulgen染色及计算机图像分析技术对离体人胸骨(取材后分别室温搁置0,1,3,5,7d)骨髓DNA含量进行定量检测。结果在较长PMI范围内,人胸骨骨髓DNA含量仍呈现下降规律。结论人胸骨骨髓DNA降解规律可望应用于较长PMI的推断。     

利用人体标本进行死亡时间推断的研究现状

死亡时间(PMI)推断具有重要的法医学意义,但尚无可以应用在实践领域的PMI推断方法。本文从PMI推断的实践应用角度出发,从脏器、骨骼、骨骼肌、牙齿、牙龈以及大体观、毛发、皮肤和血液等角度,对利用人体标本进行死亡时间推断的研究现状进行了综述。希望对我国开展人体标本的PMI推断实践研究提供借鉴。     

Compound muscle action potential analysis in different death models: significance for the estimation of early postmortem interval

In this experimental study, we investigated the varieties of excitability of gastrocnemius muscle via sciatic nerve as per different death models (asphyxia, abundant-bleeding and gradual-bleeding) on rats and the significance for the estimation of postmortem interval was evaluated. For this purpose, the rats were applied different stimulus intensities (5, 20, 40 mA) with 0.1 ms duration, before, during and every 5 min after death, using rectangular impulses, and the mean amplitude, onset latency and area values for each compound muscle action potential (CMAP) were elicited. It was detected that amplitude and area increased and onset latencies prolonged in the first postmortem 15 min. From the 15 min, CMAP area and amplitude showed an ever-increasing decrease and the prolongation of onset latencies became apparent. The decrease rate of area and amplitude was found to be statistically significantly different in asphyxia and abundant-bleeding models compared with in gradual-bleeding model, at 30 min measurements. However, there was not any significant difference in onset latency increase rates of three groups. Separately, any significant correlation between the agony and excitability periods among the groups could not be detected. The fact that the increase rate of onset latency did not show a significant difference as per death models indicated that onset latency ratios would be more appropriate criteria in determination of postmortem interval, regardless the reason of death.     

Site-dependent production of gamma-hydroxybutyric acid in the early postmortem period

This study compared endogenous gamma-hydroxybutyric acid (GHB) concentrations in various postmortem fluid samples of 25 autopsy cases. All bodies were stored between 10-20 degrees C until autopsy, and the intervals between death and autopsy were less than 2 days (6-48 h). GHB concentrations were measured by headspace gas chromatography after GHB was converted to gamma-butyrolactone. Endogenous GHB concentrations were significantly higher in femoral venous blood (4.6+/-3.4 microg/ml, n=23) than in cerebrospinal fluid (1.8+/-1.5 microg/ml, n=9), vitreous humor (0.9+/-1.7 microg/ml, n=8), bile (1.0+/-1.1 microg/ml, n=9) and urine (0.6+/-1.2 microg/ml, n=12). GHB concentrations were similar in blood samples taken from different sites. Cut-off limits of 30 and 10 microg/ml are proposed for blood and urine, respectively, to discriminate between exogenous and endogenous GHB in decedents showing no or little putrefaction (postmortem intervals usually 48 h or less). The criterion established for endogenous GHB in postmortem urine may also be applicable to analytical results in cerebrospinal fluid, vitreous humor and bile from deceased persons.     

核酸及蛋白质在死亡时间推断中的应用

死亡时间(postmortem interval,PMI)推断一直是法医学研究的重点与难点.机体死亡后,组织细胞发生自溶,核酸等大分子物质发生降解,其中DNA含量呈逐渐下降趋势,与PMI具有一定的线性关系,管家基因β-actin、GAPDH mRNA具有一定的稳定性,也可作为内参照进行PMI推测.本文综述了目前DNA、...     

家猪死后脑组织GC-MS检测和死亡时间推断的研究

目的利用GC-MS检测死后家猪脑组织的代谢产物,推断死亡时间。方法成年家猪大脑,置于25℃、75%RH的人工气候箱中,于0 h-84 h内,每间隔6 h取材,GC-MS检测各时间点脑组织代谢物变化。结果PCA显示:平台期和窗口期的时间组彼此分开。建立PLS模型,通过VIP> 1且Kruskal-Wallis检验(P <0.05)筛选出18种重要的代谢物,线性回归模型和参数检验均有统计学意义。多元回归方程为:Y_(PMI)=6.610+16.29X_(十八烷酸)+14.56X_(5-氨基缬草酸)+5.517X_(丙氨酸)(R~2=0.909、SE=6.323)或Y_(PMI)=15.78+9.690 X_(5-氨基缬草酸)+86.45X_(亮氨酸)-82.35X_(甘氨酸)(R~2=0.952、SE=4.271)。结论 GC-MS检测出家猪死后脑组织的多种产物与PMI存在显著相关性,证实了其理论和技术推断PMI的可行性。综合多指标多元逐步回归分析和PLS-DA等多元模式分析方法建立PMI推断模型,可提高推断模型的准确性和精确度。     

Analysis of gastrocnemius compound muscle action potential in rat after death: significance for the estimation of early postmortem interval

The estimation of postmortem interval is of great importance in forensic medicine. Changes in the properties of excitable tissue provide another possible means by which the time of death can be estimated. This paper reports the monitorization of the compound action potentials recorded from gastrocnemius muscle by means of sciatic nerve stimulation in rats before and after death. The sciatic nerve was stimulated using rectangular impulses of 0.1ms duration and intensities ranged between 1 and 100mA while the rat was alive. Subsequently, the rat was killed by cervical dislocation. The similar measurement procedure was performed at the moment of death and every 5min after sequentially. There was a progressive decline in amplitude values that began 10min after death. The decrease in the amplitude of the compound muscle action potentials (CMAP) was most prominent especially when elicited with lower stimulus intensities. The mean area of the CMAPs also began to decrease beginning from 15min after death. Fifteen minutes after death, the motor latencies began to prolong. Thirty-five minutes after death, the decline in amplitude and area of mean CMAP was most prominent as the mean motor latency. At the 40th minute, most of the CMAPs were unelicitable. During the early postmortem interval, these amplitude, area and motor latency alterations decrease in the amplitude and area, prolongation of motor latency seems to be well correlated with each other and this was statistically significant. These findings are discussed as possible basis of a forensic method for postmortem interval estimation.     

根据食尸性蝇类推断死亡时间的研究进展

法医昆虫学是应用昆虫学知识解决法医实践中所遇到的相关问题的一门科学。食尸性蝇类在尸体的腐败分解中发挥着重要的作用,运用食尸性蝇类的特点可以更准确进行死亡时间推断,为侦查破案提供线索。本文对依据食尸性蝇类推断死亡时间的方法进行综述,以期为后续的研究与实践应用参考和借鉴。     

运用猪眼视网膜细胞DNA降解程度推断死亡时间

目的运用单细胞凝胶电泳（single cell gel electrophoresis,SCGE）技术观察猪眼视网膜细胞DNA降解规律,推断死亡时间（postmortem interval,PMI）。方法猪死后取眼球放置于避光、温度（15&#177;2）℃、湿度（50&#177;5）%条件下,分别于2、4、6、8、10、12、14、16、18、20、22、24 h提取猪眼球视网膜细胞,进行SCGE,荧光显微镜采集图像,并运用单细胞凝胶电泳图像分析系统（IMI 1.0）进行图像分析。结果死后2～24h,视网膜细胞DNA降解程度随着PMI延长而增加;头DNA含量（%）、LT/LH、IT/IH与PMI的回归方程分别为y=92.227-5.188 x＋0.019 x^2＋0.001 x^3（R^2=0.971）、y=0.035e^0.191x（R^2=0.947）、y=0.099 e^0.264x（R^2=0.955）。结论运用SCGE检测视网膜细胞DNA降解情况有助于推断PMI。     

Efficacy of entomological method in estimation of postmortem interval: a comparative analysis

Sixteen insect-infested cadavers were examined and analysed to evaluate the reliability of the entomological method in estimation of time elapsed since death, in relation to other medico-legal approaches. The entomological method was found statistically more reliable and superior when compared to other prevalent methods.     

组织RNA检测用于死亡时间推断的研究进展

近几年来利用RNA的降解程度来推断死亡时间已逐渐成为法医学研究热点.本文复习相关研究文献,对大鼠不同组织(脑组织、心脏组织、肝脏组织和肾组织等)中RNA在推断死亡时间的具体应用方法做出总结,归纳出不同组织中的各类RNA在推断死亡时间方面的适用范围,以及对此种方法在推断死亡时间的过程中产生的问题及可行性的解决方法.     

A new perspective in the estimation of postmortem interval (PMI) based on vitreous

The relation between the potassium concentration in the vitreous humor, [K+], and the postmortem interval has been studied by several authors. Many formulae are available and they are based on a correlation test and linear regression using the PMI as the independent variable and [K+] as the dependent variable. The estimation of the confidence interval is based on this formulation. However, in forensic work, it is necessary to use [K+] as the independent variable to estimate the PMI. Although all authors have obtained the PMI by direct use of these formulae, it is, nevertheless, an inexact approach, which leads to false estimations. What is required is to change the variables, obtaining a new equation in which [K+] is considered as the independent variable and the PMI as the dependent. The regression line obtained from our data is [K+] = 5.35 + 0.22 PMI, by changing the variables we get PMI = 2.58[K+] - 9.30. When only nonhospital deaths are considered, the results are considerably improved. In this case, we get [K+] = 5.60 + 0.17 PMI and, consequently, PMI = 3.92[K+] - 19.04.     

根据肝脏死后改变推断死亡时间的研究进展

机体死后会发生一系列的改变,是腐败的过程,也是器官组织细胞自溶的过程。在司法实践中,通过研究肝脏死后改变,可以更准确的推断死亡时间,为案件的侦破提供线索。本文综述了近几十年来,利用肝脏死后变化推断死亡时间的研究进展。     

大鼠肝细胞DNA含量与早期死亡时间关系的图像分析研究

实验选择 15只大鼠 ,处死后 ,在 2 4h内 ,每隔 1h取肝组织块进行细胞学涂片、福尔马林液固定、Feul gen染色、自动图像分析仪测量、统计学处理数据。结果表明 ,肝细胞DNA含量在死后 2 4h内 ,随死亡时间的延长而较有规律的下降。其中积分光密度、平均光密度、异形指数是用来研究死亡 2 4h内肝细胞DNA降解规律 ,并准确推断死亡时间的较好指标。     

利用猪胸主动脉生物力学性能时序性变化推断死亡时间

目的观察分析家猪尸体胸主动脉生物力学性状指标的变化规律,探讨其在死亡时间(PMI)推断中的应用价值。方法采集180根家猪的主动脉,在恒定温度、湿度下,于2～230h之间每间隔12h设置1个取检材时间点组;各组主动脉检材用电子万能材料试验机拉伸检测极限载荷、极限载荷变形、平均力、应力、应变,宽度和厚度等生物力学参数指标;应用多元逐步回归方法进行统计学分析。结果家猪死后230h内,随PMI延长,胸主动脉大体观呈自溶腐败性变色、瘫软、液化趋势。生物力学参数指标中,极限载荷、平均力和应力呈随PMI延长呈明显下降趋势,PMI间隔24h组间比较差异性均有统计学意义(P<0.05),校正决定系数分别为0.923、0.806、0.867,估计标准误差分别为±18.39h、±29.88h、±24.58h,PMI间隔24h组间比较差异性均有统计学意义(P<0.05),其它指标与PMI之间相关性不显著均P>0.05。结论死后230h内家猪胸主动脉的极限载荷、平均力和应力的死后时序性变化,与PMI呈明显的负相关性,可用于PMI推断,其中极限载荷效果最佳。     

大鼠死后腓肠肌直接电兴奋性变化与早期死亡时间的关系

目的探讨大鼠死亡后不同时间腓肠肌电兴奋性的变化,为早期死亡时间的推断提供新的指标。方法建立大鼠机械性窒息模型,利用电生理检测仪检测死亡后不同时间大鼠腓肠肌对不同强度的电刺激的反应性,记录肌肉组织动作电位出现时间,统计学分析其差异并建立回归方程。结果大鼠机械性窒息死亡后一定时间内,其腓肠肌对电刺激的兴奋性与死亡时间呈明显线性关系。结论肌肉组织的电兴奋性可以作为早期死亡时间推断的有效指标。