New Advances, Challenges and Opportunities in Forensic Applications of Microbiomics / 法医学杂志

The succession of microbiota is closely associated with several essential factors, including race, sex, health condition, lifestyle, postmortem interval, etc., and it has great potential application value in forensic medicine. This paper summarizes recent studies on the forensic applications of the microbiome, including individual identification, geographical feature identification, origin identification of the tissue or body fluid, and postmortem interval estimation, and introduces the current machine learning algorithms for microbiology research based on next-generation sequencing data. In addition, the current problems facing forensic microbiomics such as the extraction and preservation of samples, construction of standardization and database, ethical review and practical applicability are discussed. Future multi-omics studies are expected to explore micro ecosystems from a comprehensive and dynamic perspective, to promote the development of forensic microbiomics application.

Visualization of Literature Information on Postmortem Interval Estimation Indexed by CNKI Database from 1990 to 2020 / 法医学杂志

OBJECTIVES@#To explore the development process of the postmortem interval (PMI) research in China from January 1990 to August 2020, research hotspots in different periods, authors and cooperation between institutions, and to provide a reference for the better development of PMI inference research through the visualization of the literature information of the PMI estimation research indexed in China National Knowledge Infrastructure (CNKI).@*METHODS@#The information visualization analysis software CiteSpace 5.7.R1 was used to carry out big data analysis on hotspots, high-frequency keywords, authors, institutions and other information in the research literature on PMI inference from January 1990 to August 2020 indexed in CNKI.@*RESULTS@#The peak time of publication of PMI was from 2006 to 2010 with 114 articles. In keyword co-occurrence network, the effective hot words were forensic entomology, DNA content analysis and some emerging words such as artificial intelligence and big data. In the cooperation network of institutions, the high-frequency institutions were mainly the scientific research institutions. The author cooperation network showed a trend of co-aggregation and multi-cooperation.@*CONCLUSIONS@#With the development of science and technology, the research on PMI estimation based on traditional methods is mature and novel strategies are emerging. Big data and artificial intelligence combined with forensic science provide new research directions on PMI estimation.

Estimating Postmortem Interval Using Intestinal Microbiota Diversity Based on 16S rRNA High-throughput Sequencing Technology / 法医学杂志

OBJECTIVES@#To explore the correlation between intestinal microbiota and postmortem interval(PMI) in rats by using 16S rRNA high-throughput sequencing technology.@*METHODS@#Rats were killed by anesthesia and placed at 16 ℃, and DNA was extracted in caecum at 14 time points of 0, 1, 2, 3, 5, 7, 9, 12, 15, 18, 21, 24, 27 and 30 d after death. The 16S rRNA high-throughput sequencing technology was used to detect intestinal microbiota in rat cecal contents, and the results were used to analyze the rat intestinal microbiota diversity and differences.@*RESULTS@#The total number of intestinal microbial communities did not change significantly within 30 days after death, but the diversity showed an upward trend. A total of 119 bacterial communities were significantly changed at 13 time points after death. The models for PMI estimation were established by using partial least squares (PLS) regression at all time points, before 9 days and after 12 days, reaching an R2 of 0.795, 0.767 and 0.445, respectively; and the root mean square errors (RMSEs) were 6.57, 1.96 and 5.37 d, respectively.@*CONCLUSIONS@#Using 16S rRNA high-throughput sequencing technology, the composition and structure of intestinal microbiota changed significantly within 30 d after death. In addition, the established PLS regression model suggested that the PMI was highly correlated with intestinal microbiota composition, showing a certain time series change.

Application of Sarcosaprophagous Insects to Estimate the Postmortem Interval in 11 Cases / 法医学杂志

Objective To test the feasibility and accuracy of with sarcosaprophagous insects postmortem interval （PMI） estimation with sarcosaprophagous insects and provide references for estimation practice. Methods Eleven cases confirmed by the detection results, with complete entomological evidence were selected. The insect species, estimation results and true results involved in the cases were statistically analyzed and compared. Results Thirteen species of insects were found at the criminal scene, including Chrysomya megacephala （Fabricius）, Chrysomya rufifacies （Macquart）, Chrysomya nigripes （Aubertin）, Lucilia sericata （Meigen）, Hydrotaea spinigera Stein, Muscina stabulans （Fallén）, Sarcophagid （species were not identified）, Megaselia scalaris （Loew）, Hermetia illucens （Linnaeus）, Saprinus splendens （Paykull）, Creophilus maxillosus （Linnaeus）, Dermestes maculatus （De Geer） and Necrobia ruficollis （Fabricius）. The PMI of all eleven cases was within the range of estimated PMI. The estimated results of 72.73% cases were on the same day of the true results. Conclusion Sarcosaprophagous insects can estimate the PMI simply and conveniently. In cases where the PMI is within the time range of one generation of flies or beetles, the estimation results are relatively accurate. However, the estimation is less accurate when the PMI is beyond the time range.

Progress and Application of Entomological Evidence in Forensic Science / 法医学杂志

Entomological evidence provides entry points and clues for cases detection, in terms of estimation of the postmortem interval （PMI）, and place and cause of death. In recent years, the feasibility of entomological evidence in practice has been proved by theories and cases. It especially plays an important role in the investigation of cases with unnatural death, no monitoring, and highly corrupt cadaver. However, there are still some key issues to be further studied and standardized before the application of entomological evidence to forensic practice, to improve the effect of entomological evidence in forensic investigation and trial. This paper retrospectively reviews key studies of the application of entomological evidence in forensic science, mainly including discussion of forensic entomology inspection standard, identification studies of sarcosaprophagous insect species, collection of sarcosaprophagous insect growth and succession data under different environments and forensic entomotoxicology. With the rapid development of information technology and biotechnology, applying artificial intelligence and whole genome sequencing technology in forensic entomology has become a new research direction, which can improve the application value and range of entomological evidence in forensic science.

Métodos histoquímicos e inmunohistoquímicos para la estimación del Intervalo postmortem en tejidos humanos: una revisión / Histochemical and immunohistochemical methods for the postmortem interval estimation in human tissues: a review

El intervalo postmortem (IPM) es un importante desafío a resolver en patología forense, y consiste en poder determinar el tiempo transcurrido desde la muerte hasta el momento de la autopsia. Dada la poca confiablidad de algunos métodos por la gran influencia de factores externos, la Histoquímica (HQ) y la Inmunohistoquímica (IHQ), entre otros, han recibido considerable atención por sus niveles de objetividad en la investigación forense. Se presenta una revisión con búsqueda sistemática de estudios experimentales que apliquen métodos HQs e IHQs para la estimación del IPM sobre material cadavérico humano. Se identificaron 1053 artículos de los cuales 12 cumplieron con los criterios, a los que se agregaron 4 mediante una búsqueda manual (n=16 artículos). Alemania fue el país con más publicaciones destacando con 8 artículos. Las técnicas HQs de AgNORs, TRAP y PAS fueron utilizadas en 5 estudios (glándulas sudoríparas, piel, hígado, médula ósea y mucosa labial), mientras que las IHQs fueron empleadas con diferentes grupos antigénicos en 12 estudios (páncreas, cerebro, pulmón, tiroides, hígado, glándulas pituitarias, glándulas sudoríparas y mucosa gingival). Las estimaciones del IPM fueron posibles con márgenes entre 2-3 h. hasta los 20 días dependiendo de la técnica. El análisis de tejidos provenientes de cavidad oral asegura una vía no invasiva, de fácil acceso y bajo resguardo natural a la influencia de factores ambientales. Si bien no existe un método único que permita de manera confiable estas estimaciones, la introducción de nuevas técnicas permitiría evitar la producción de errores.

The postmortem interval (IPM) is an important challenge to be solved in forensic pathology, and it consists in determine the time elapsed since death until the autopsy. Given the low reliability of some methods due to the great influence of external factors, Histochemistry (HQ) and Immunohistochemistry (IHQ), among others, have received considerable attention for their levels of objectivity in forensic investigation. A scoping review of experimental studies that apply HQs and IHQs methods to estimate the MPI on human cadaveric material is presented. We identified 1053 articles, of which 12 met the criteria; we added 4 articles through a manual search (n = 16 articles). Germany was the most productive country, with 8 articles. HQ techniques of AgNORs, TRAP and PAS were used in 5 studies (on sweat glands, skin, liver, bone marrow and labial mucosa), while IHQs techniques were used with different antigenic groups in 12 studies (on pancreas, brain, lung, thyroid, liver, pituitary glands, sweat glands and gingival mucosa). IPM estimates were possible with margins between 2-3 hours up to 20 days depending on the technique. The analysis of oral tissues ensures a non-invasive route, easily accessible and under natural protection to the influence of environmental factors. Although there is no single method that reliably allows these estimates, the introduction of new techniques would prevent the production of errors.