春季尸体腹腔腐败气压在法医学死亡时间推断中的应用研究

目的 研究尸体腹腔腐败气压在春季的发展变化规律及其用于推断死后经过时间的方法。方法用实验动物山羊57只,分陆地处死和水中溺死两大组,用自行研制的“腐败气压测定仪”,定时系统测量动物尸体腹腔内的腐败气压。结果 得出尸体腹腔内腐败气压的发展变化规律,并据此建立测量腹腔腐败气压推断死后经过时间的方法。研究了数种死亡方式、尸体所处环境和个体差异等的影响。结论 该研究成果填补了法医学中尸体腐败气压发展变化规律研究、检测腐败气压推算死后经过时间和腐败气压测定仪等的多项空白,丰富了该领域的法医学内容。     

家兔角膜上皮和内皮细胞DNA含量与PMI关系的图像分析

目的 探讨家兔角膜上皮和内皮细胞DNA含量与PMI的关系。方法 应用计算机图像分析技术,测定105只家兔死后72h内不同时间点家兔角膜上皮和内皮细胞核DNA含量(IOD)的变化值并做统计学分析。结果 家兔死后72h内其角膜上皮细胞和内皮细胞核DNA降解速率与PMI具有显著的相关性,并由此归纳出体现DNA降解趋势的二项式回归方程。结论 应用计算机图像分析技术,测量机体死后角膜内外皮细胞DNA含量变化,将会成为推断PMI精确、客观的新方法。     

利用尸体角膜内皮细胞活性率判定死后经过时间的研究

本研究对已知死亡时间的500只非正常死亡者的角膜内皮细胞进行染色观察，以单位面积内的活性内皮细胞与细胞总数之比作为活性率，发现角膜内皮细胞活性率（Endothelialcelllivinsrate，ECLR）随死后经过时间（postmorteminterval，PMI）的延长而逐渐降低，数理分析表明两者之间的关系为负相关，因此，认为检测尸体角膜内皮细胞活性的方法可为法医学推断死后经过时间提供一新的组织学手段。     

Post-mortem interval estimation using miRNAs of road traffic accident cases: A forensic molecular approach

In forensic examination accurate estimation of post-mortem interval (PMI) is a challenging task, particularly in the advanced stages of decomposition. The existing methods (algor mortis, livor mortis, rigor mortis, putrefaction etc) used for estimating PMI rely on analyzing the physical, biochemical, and metabolic changes that occur in the corpse after death. While these methods have shown some level of effectiveness in estimating PMI during the early stages of decomposition, accurate estimation becomes increasingly challenging during the later stages of putrefaction when the body undergoes significant changes. Recently, microRNA (miRNA) profiling due to its relatively small size and stability has emerged as a promising tool in several areas of forensics. This study demonstrates the potential of miRNA for PMI estimation in advanced stages of death. In this study, miRNA-195, miRNA-206, and miRNA-378 were selected as target miRNAs and miRNA-1 as reference miRNA. Left ventricle tissue (5 g) of the heart from 20 forensic autopsies of traffic accident victims (18–32 years) were collected and processed. The samples were held at room temperature for eight different time intervals (12, 24, 48, 72, 96, 120, 168 and 196 h), and RNA was extracted from all the samples using Trizol-based RNA isolation protocol, followed by cDNA synthesis and amplification with commercially available specific miRNA probes in Real-Time PCR (RT-PCR), Ct was calculated. The result showed that miRNAs were associated with PMI. Over time, there were substantial changes in the Ct values of all three miRNAs, with significant reductions observed at 196 h compared to 12 h. miRNA-206 demonstrated significant changes at multiple time intervals, while miRNA-1 remained stable for up to 196 h and thus holds caas an endogenous marker. In conclusion, miRNA has the potential to serve as a valuable tool for estimating PMI, especially during the advanced stages of decomposition, when used in conjunction with established techniques. However, further validation of the study is required to obtain more accurate estimates of PMI.     

Time-related changes in cardiac ct images of rabbits died from four kinds of execution

Objective To explore the feasibility and appropriate parameters for estimating postmortem interval (PMI) through time-related CT imaging into dynamically monitoring the cardiac changes of rabbits died from four kinds of execution. Methods The experimental rabbits were executed with four disposals of air embolism, strangulation, drowning and hemorrhagic shock. The dead rabbits were observed of their hearts with CT scanning every 6 hours within 120h from the death moment, having the obtained time-different CT images and mean CT values examined. With the cardiac average CT values of rabbits died from discrepant execution, four relevant regression equations were established against the elapsing time (i.e. PMI). Results The CT images of post-death cardiac tissue of rabbits died from one of four executions did change regularly with the PMI elongating, showing consistent with the autopsy verification. The binomial regressive equations were established between the post-death cardiac average CT value and PMI from four executions, demonstrating statistically significant (P<0.05). Conclusion The postmortem cardiac CT imaging into PMI analysis, plus the relating regression equation, provides a new objective visual quantitative approach and reference for forensic medicine to infer the time of death. © 2021, Editorial Office of Forensic Science and Technology. All rights reserved.     

Diurnal and Nocturnal Flight Activity of Blow Flies (Diptera: Calliphoridae) in a Rainforest Fragment in Brazil: Implications for the Colonization of Homicide Victims

Nocturnal flight of blow flies (Diptera: Calliphoridae) is a controversial issue in forensic entomology. We performed two field experiments to investigate the diurnal and nocturnal activity of six blow fly species in a rainforest fragment in Brazil. Initially, nocturnal (17:30–05:30) versus diurnal (05:30–17:30) flight activity was investigated. Only 3.9% of adults were collected at night, mostly the native species Mesembrinella bicolor, and nocturnal oviposition did not occur. In the second experiment, collection of adults took place at the following intervals: 05:30–08:30, 08:30–11:30, 11:30–14:30, and 14:30–17:30. The proportions of adults did not differ significantly among the four diurnal intervals, except for Hemilucilia segmentaria, which was captured more frequently in the early morning. Calliphoridae has predominantly diurnal behavior, not laying eggs in darkness. The association of the native species M. bicolor, Hemilucilia semidiaphana, and H. segmentaria to forested areas reinforces the forensic relevance of data on their flight pattern.     

早期死亡时间推断研究进展

死亡时间推断在判断案件的性质、划定侦查范围及锁定嫌疑人等方面至关重要,一直是法医病理学工作的重点和难点。早期死亡时间,即指死后24 h以内,由于距离案发时间更短,对其准确推断能促进案件的成功侦破,具有重要的法医学意义。近年来,国内外法医学者运用一系列新方法和新技术对早期死亡时间推断进行了大量研究。本文对体液生物化学、超生反应、代谢组学、影像学、遗传物质降解规律等方面的研究进展进行综述,以期为早期死亡时间推断的研究和应用提供新的思路。     

死后大鼠脾脏组织FTIR测量结果的法医学分析

目的应用傅里叶变换红外（FTIR）光谱技术分析大鼠死后脾脏组织随死亡时间增加的化学变化过程,为死亡时间推断研究提供新的途径与研究数据。方法大鼠断颈处死后,在30℃、20℃及4℃环境中,不同死亡时间点提取大鼠脾脏组织,并运用FTIR光谱仪测定不同化学基团随死亡时间的变化。结果随着死亡时间的推移,大鼠脾脏组织FTIR光谱的主要吸收峰峰位没有明显变化,而其吸收峰强度有明显差异：（1）1080cm-1和1238cm-1被指认核酸谱带吸收峰的峰强呈下降趋势;（2）1541cm-1被指认酰胺Ⅱ吸收峰的峰强呈上升变化;（3）1396cm-1被指认脂肪酸吸收峰的峰强呈上升变化;（4）指认为C-H结构振动的2852、2871、2923、2958cm-1吸收峰的峰强呈现上升趋势。结论 FTIR光谱分析技术有望成为法医死亡时间推断的有效方法。     

Sequences of the Cytochrome C Oxidase Subunit I (COI) Gene are Suitable for Species Identification of Korean Calliphorinae Flies of Forensic Importance (Diptera: Calliphoridae)

Abstract:  Calliphorinae fly species are important indicators of the postmortem interval especially during early spring and late fall in Korea. Although nucleotide sequences of various Calliphorinae fly species are available, there has been no research on the cytochrome c oxidase subunit I (COI) nucleotide sequences of Korean Calliphorinae flies. Here, we report the full-length sequences of the COI gene of four Calliphorinae fly species collected in Korea (five individuals of Calliphora vicina , five Calliphora lata , four Triceratopyga calliphoroides and three Aldrichina grahami ). Each COI gene was amplified by polymerase chain reaction and directly sequenced and the resulting nucleotide sequences were aligned and analyzed by MEGA4 software. The results indicate that COI nucleotide sequences can be used to distinguish between these four species. Our phylogenetic result coincides with recent taxonomic views on the subfamily Calliphorinae in that the genera Aldrichina and Triceratopyga are nested within the genus Calliphora .     

The potential to determine a postmortem submersion interval based on algal/diatom diversity on decomposing mammalian carcasses in brackish ponds in Delaware

Recently botanical evidence has been studied to determine if it is useful in forensic investigations. This study was performed to examine stillborn piglet decomposition in a brackish water environment and to semi-quantitatively document stages of decomposition, degree day accumulation per stage as well as the algal/diatom diversity useful in determining a postmortem submersion interval (PMSI). Piglets and ceramic tiles were submerged in brackish ponds and sampled on a regular basis to document algal diversity and succession between substrates and stages of decomposition. Significantly greater weight was lost from piglet carcasses during the early floating and advanced floating decay stages. Seasonal effects were observed in degree-day accumulations. Diatom diversity was significantly greater on piglet carcasses compared to tile substrates. Algal diversity decreased over time on the piglet carcasses as well as the stage of decomposition. A significant relationship and strong correlation between algal diversity found on the piglet substrate with time was observed. Our results indicate that more research is needed to examine the potential to use diatoms in not only determining manner of death but also the duration of time (PMSI) a victim may have been immersed in an aquatic environment.