Partial sequencing of the cytochrome oxydase b subunit gene I: a tool for the identification of European species of blow flies for postmortem interval estimation

The identification of insects found on a dead body can lead to the estimation of the time of death (postmortem interval). We report an updated version of an established method based on sequence analysis of PCR products from a region of the cytochrome b oxidase subunit I mitochondrial gene of different members of the family Calliphoridae, by sequencing six European species: Lucilia sericata (Meigen), Lucilia caesar (Linné), Lucilia illustris (Meigen), Calliphora vicina (Robineau-Desvody), Calliphora vomitoria (Linné), Protophormia terraenovae (Robineau-Desvody) and one Guianese species: Cochliomyia macellaria (Fabricius). This technique provided clear results when applied to the larvae and we also report the identification of empty puparia.     

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±2）℃、湿度（50±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。     

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。     

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.     

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。     

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、...     

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。     

The use of absolute refractory period in the estimation of early postmortem interval

The estimation of the time since death (postmortem interval) is one of the most difficult problems in forensic pathology. Most methods currently employed use temperature-based algorithms intended to model the cooling of the body after death and thus estimate the postmortem interval. These methods are subject to considerable inaccuracy but their reliability can be improved if a range of other observed criteria such as lividity and rigor are also taken into consideration. The aim of the present study was to investigate the feasibility of using the absolute refractory period as an adjunct to the estimation of postmortem interval. The relationship between the `postmortem interval' and the `duration of absolute refractory period' was investigated using the rat sciatic nerve. A strong correlation between the duration of the absolute refractory period and the postmortem interval was observed. When both absolute refractory period and temperature were used in conjunction, the strength of this correlation was increased.     

基于角膜图像的人体死亡时间推断模型初探

目的尸体角膜随死后时间延长发生的形态学变化是规律性较好的指标,常用来判断死亡时间(postmortem interval,PMI)。本文尝试用机器视觉代替人的肉眼主观判断,收集尸体样本以建立通过人体角膜图像推断PMI的模型。方法收集实际案例建立包含505例人体死后角膜图像的数据库,PMI范围为0.24h(约死后14min)至492h(约死后20.5d),大致分为三类(依次为:0~<6h、6~<20h、20h及以上)或二类(0~<15h、15h及以上);使用由华盛顿大学陈天奇博士提出的Xgboost模型分别进行二分类与三分类分析;使用多种卷积神经网络模型分别进行分类和回归学习,并通过比较最终选择了由微软研究院提出的ResNet模型进行分析。结果Xgboost在三分类时预测准确率依次为71.8%、40.7%、65.7%,二分类时为90%、48.5%。ResNet分类模型中,精准率、召回率在三分类时分别依次为:81%、75%,30%、50%,61%、71%,二分类时为:70%、92%,76%、38%。ResNet回归模型中,比较整个模型的预测结果,0~6h内的预测值与真实值较为接近,均值误差为0.5616,均方误差为0.5873,6h之后开始出现较大误差。结论分类和回归模型都在0~6h之内得到了很好的结果,说明在此时间段内,角膜图像噪声较低,可预测性强。     

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。     

Survival of submerged blowfly species and their parasitoids: implications for postmortem submersion interval

Pupal survival of three blowfly species, Chrysomya albiceps, Chrysomya megacephala, and Chrysomya putoria (Diptera: Calliphoridae) and the parasitoid species Nasonia vitripennis (Hymenoptera: Pteromalidae) was studied after the pupae were experimentally submerged in water. Non-parasitized pupae at different developmental stages, 0, 24, 48, and 72 h, and parasitized pupae after 3, 8, 10, and 12 days of development were submerged for 6, 24, 48, or 72 h. Control groups for each pupal developmental stage (parasitized or not), which were not submerged, were also observed in order to compare the adult emergence rates. The survival of white pupae (0 h/age) decreased with time of submergence for all three blowfly species, showing the lowest rates compared with other experimental pupa groups. For the three blowfly species, non-parasitized pupae at 24 and 48 h of age showed survival rates above 60%. However, for pupae at 72 h of age, the survival rates decreased with increased underwater time, with less than 30% survival after 72 h in C. putoria and C. albiceps. The survival of parasitoids inside blowfly pupae that were submerged during their larval stage (3 days/age) decreased with the increase of submergence time. After the parasitoids reached the pre-pupal life stage, the survival was higher for all underwater periods. These observations can be useful in investigations of the decomposition of partially submerged bodies, or in cases of pupae found adhering to decaying flesh, hair, or clothes of corpses that were submerged after the larvae had developed and pupated.     

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.     

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。     

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.     

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.     

Comparison of chemical methods for determining postmortem interval

Accurate determination of postmortem interval (PMI) is a problem for the forensic thanatologist, especially in unwitnessed deaths. A number of objective chemical methods for determining PMI have been developed, the most widely used being accumulation of potassium in the vitreous humor. The authors previously have reported a chemical method for determining PMI from the predictable accumulation or clearance of the dopaminergic metabolite 3-methoxytyramine (3-MT) in the putamen of the brain. They have extended their previous study to compare directly the accuracy of determining PMI from the level of 3-MT in putamen with the level of potassium in vitreous humor. The data indicate that 3-MT is at least as accurate as, if not more accurate than, potassium accumulation in vitreous humor, although 3-MT levels can be affected by the cause of death and drugs present at the time of death. Nevertheless, determination of both the 3-MT and potassium levels can afford the most accurate method of determining PMI; preliminary nomograms for determining PMI from both variables are presented.     

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。     

根据绿蝇属昆虫推断死亡时间的法医学研究进展

尸源性昆虫在某些刑事案件的侦破中占有重要地位,对于推断死者的死亡时间和推断尸体是否有转移有重要的作用。双翅目中的丽蝇科绿蝇属昆虫是尸体上常见的昆虫之一,通常最先到达尸体,而且最喜阳光,该特点以及在尸体上发现的绿蝇属昆虫幼虫的生长发育阶段,可以为刑事案件的侦破提供十分有力的证据。本文主要从生物形态学和分子生物学对绿蝇的种属鉴定以及绿蝇日龄的推断等方面,综述了根据绿蝇属昆虫推断死亡时间的法医学应用研究进展。