Vitreous humour as a potential DNA source for postmortem human identification

PURPOSE: The aim of this study was the assessment of vitreous humor as a potential DNA for forensic human postmortem identification. MATERIAL AND METHODS: Vitreous humor samples were collected using two alternative approaches from 25 corpses of either sex during autopsies. DNA was extracted by standard organic method. Recovered DNA was quantitiated fluorometrically. AmpFlSTR SGM Plus kit and ABI 310 Genetic Analyzer (Applera) were used to obtain genetic profiles. RESULTS: Different DNA yields were quantitated in vitreous body depending on cause of death and sampling approach. CONCLUSION: Vitreous humor is a potential DNA for forensic human postmortem identification depending on a sampling method used.     

A checklist of arthropods associated with pig carrion and human corpses in southeastern brazil

Necrophagous insects, mainly Diptera and Coleoptera, are attracted to specific stages of carcass decomposition, in a process of faunistic succession. They are very important in estimating the postmortem interval, the time interval between the death and the discovery of the body. In studies done with pig carcasses exposed to natural conditions in an urban forest (Santa Genebra Reservation), located in Campinas, State of S?o Paulo, southeastern Brazil, 4 out of 36 families of insects collected - Calliphoridae, Sarcophagidae, Muscidae (Diptera) and Dermestidae (Coleoptera) - were considered of forensic importance, because several species were collected in large numbers both visiting and breeding in pig carcasses. Several species were also observed and collected on human corpses at the Institute of Legal Medicine. The species belonged to 17 different families, 6 being of forensic importance because they were reared from human corpses or pig carcasses: Calliphoridae, Sarcophagidae, Muscidae, Piophilidae (Diptera), Dermestidae, Silphidae and Cleridae (Coleoptera). The most important species were: Diptera - Chrysomya albiceps, Chrysomya putoria, Hemilucilia segmentaria, Hemilucilia semidiaphana (Calliphoridae), Pattonella intermutans (Sarcophagidae), Ophyra chalcogaster (Muscidae), Piophila casei (Piophilidae); Coleoptera - Dermestes maculatus (Dermestidae), Oxyletrum disciolle (Silphidae) and Necrobia rufipes (Cleridae).     

我国嗜尸性蝇类的鉴别、发育及演替研究现状与分析

嗜尸性蝇类是法医昆虫学调查中最重要的目标,作为早期到达尸体并主要促成尸体组织腐解的昆虫,对死亡时间的推断,特别是腐败尸体死亡时间的推断具有重大意义。本文针对我国嗜尸性蝇类的主要种类及形态识别、各种类生长发育、在尸体上的演替进行了综述。     

Functional and Structural Succession of Soil Microbial Communities below Decomposing Human Cadavers

The ecological succession of microbes during cadaver decomposition has garnered interest in both basic and applied research contexts (e.g. community assembly and dynamics; forensic indicator of time since death). Yet current understanding of microbial ecology during decomposition is almost entirely based on plant litter. We know very little about microbes recycling carcass-derived organic matter despite the unique decomposition processes. Our objective was to quantify the taxonomic and functional succession of microbial populations in soils below decomposing cadavers, testing the hypotheses that a) periods of increased activity during decomposition are associated with particular taxa; and b) human-associated taxa are introduced to soils, but do not persist outside their host. We collected soils from beneath four cadavers throughout decomposition, and analyzed soil chemistry, microbial activity and bacterial community structure. As expected, decomposition resulted in pulses of soil C and nutrients (particularly ammonia) and stimulated microbial activity. There was no change in total bacterial abundances, however we observed distinct changes in both function and community composition. During active decay (7 - 12 days postmortem), respiration and biomass production rates were high: the community was dominated by Proteobacteria (increased from 15.0 to 26.1% relative abundance) and Firmicutes (increased from 1.0 to 29.0%), with reduced Acidobacteria abundances (decreased from 30.4 to 9.8%). Once decay rates slowed (10 - 23 d postmortem), respiration was elevated, but biomass production rates dropped dramatically; this community with low growth efficiency was dominated by Firmicutes (increased to 50.9%) and other anaerobic taxa. Human-associated bacteria, including the obligately anaerobic Bacteroides, were detected at high concentrations in soil throughout decomposition, up to 198 d postmortem. Our results revealed the pattern of functional and compositional succession in soil microbial communities during decomposition of human-derived organic matter, provided insight into decomposition processes, and identified putative predictor populations for time since death estimation.     

Predicting postmortem interval based on microbial community sequences and machine learning algorithms

Microbes play an essential role in the decomposition process but were poorly understood in their succession and behaviour. Previous researches have shown that microbes show predictable behaviour that starts at death and changes during the decomposition process. Research of such behaviour enhances the understanding of decomposition and benefits estimating the postmortem interval (PMI) in forensic investigations, which is critical but faces multiple challenges. In this study, we combined microbial community characterization, microbiome sequencing from different organs (i.e. brain, heart and cecum) and machine learning algorithms [random forest (RF), support vector machine (SVM) and artificial neural network (ANN)] to investigate microbial succession pattern during corpse decomposition and estimate PMI in a mouse corpse system. Microbial communities exhibited significant differences between the death point and advanced decay stages. Enterococcus faecalis, Anaerosalibacter bizertensis, Lactobacillus reuteri, and so forth were identified as the most informative species in the decomposition process. Furthermore, the ANN model combined with the postmortem microbial data set from the cecum, which was the best combination among all candidates, yielded a mean absolute error of 1.5 ± 0.8 h within 24-h decomposition and 14.5 ± 4.4 h within 15-day decomposition. This integrated model can serve as a reliable and accurate technology in PMI estimation.     

Comprehensive postmortem analyses of intestinal microbiota changes and bacterial translocation in human flora associated mice

Background

Postmortem microbiological examinations are performed in forensic and medical pathology for defining uncertain causes of deaths and for screening of deceased tissue donors. Interpretation of bacteriological data, however, is hampered by false-positive results due to agonal spread of microorganisms, postmortem bacterial translocation, and environmental contamination.

Methodology/Principal Findings

We performed a kinetic survey of naturally occurring postmortem gut flora changes in the small and large intestines of conventional and gnotobiotic mice associated with a human microbiota (hfa) applying cultural and molecular methods. Sacrificed mice were kept under ambient conditions for up to 72 hours postmortem. Intestinal microbiota changes were most pronounced in the ileal lumen where enterobacteria and enterococci increased by 3–5 orders of magnitude in conventional and hfa mice. Interestingly, comparable intestinal overgrowth was shown in acute and chronic intestinal inflammation in mice and men. In hfa mice, ileal overgrowth with enterococci and enterobacteria started 3 and 24 hours postmortem, respectively. Strikingly, intestinal bacteria translocated to extra-intestinal compartments such as mesenteric lymphnodes, spleen, liver, kidney, and cardiac blood as early as 5 min after death. Furthermore, intestinal tissue destruction was characterized by increased numbers of apoptotic cells and neutrophils within 3 hours postmortem, whereas counts of proliferative cells as well as T- and B-lymphocytes and regulatory T-cells decreased between 3 and 12 hours postmortem.

Conclusions/Significance

We conclude that kinetics of ileal overgrowth with enterobacteria and enterococci in hfa mice can be used as an indicator for compromized intestinal functionality and for more precisely defining the time point of death under defined ambient conditions. The rapid translocation of intestinal bacteria starting within a few minutes after death will help to distinguish between relevant bacteria and secondary contaminants thus providing important informations for routine applications and future studies in applied microbiology, forensic pathology, and criminal medicine.     

Moral considerations in body donation for scientific research: a unique look at the University of Tennessee's anthropological research facility

This paper discusses keys to the moral procurement, treatment and disposition of remains used for scientific research, specifically those donated to the University of Tennessee's Anthropological Research Facility (ARF). The ARF is an outdoor laboratory dedicated to better understanding the fate of human remains in forensic contexts, and focuses its research on decomposition, time since death estimates, body location and recovery techniques, and skeletal analysis. Historically, many donations were unclaimed bodies received from medical examiners (although it will be shown that this trend is changing), and it has been argued that the use of the unclaimed bodies for medical or scientific purposes is a violation of autonomy since no consent was given by the individual. It is argued here, however, that the domain of autonomous choice extends to one's own corpse only insofar as expressed wishes are made known prior to one's death, and that in the absence of expressed intent toward final disposition, it is acceptable for institutions to receive donations from medical examiners or family members. This paper also discusses other philosophical issues related to donation, consent and autonomy, and the forensic benefits of research conducted at the Anthropological Research Facility.     

Comparison of the Decomposition VOC Profile during Winter and Summer in a Moist,Mid-Latitude (Cfb) Climate

The investigation of volatile organic compounds (VOCs) associated with decomposition is an emerging field in forensic taphonomy due to their importance in locating human remains using biological detectors such as insects and canines. A consistent decomposition VOC profile has not yet been elucidated due to the intrinsic impact of the environment on the decomposition process in different climatic zones. The study of decomposition VOCs has typically occurred during the warmer months to enable chemical profiling of all decomposition stages. The present study investigated the decomposition VOC profile in air during both warmer and cooler months in a moist, mid-latitude (Cfb) climate as decomposition occurs year-round in this environment. Pig carcasses (Sus scrofa domesticus L.) were placed on a soil surface to decompose naturally and their VOC profile was monitored during the winter and summer months. Corresponding control sites were also monitored to determine the natural VOC profile of the surrounding soil and vegetation. VOC samples were collected onto sorbent tubes and analyzed using comprehensive two-dimensional gas chromatography – time-of-flight mass spectrometry (GC×GC-TOFMS). The summer months were characterized by higher temperatures and solar radiation, greater rainfall accumulation, and comparable humidity when compared to the winter months. The rate of decomposition was faster and the number and abundance of VOCs was proportionally higher in summer. However, a similar trend was observed in winter and summer demonstrating a rapid increase in VOC abundance during active decay with a second increase in abundance occurring later in the decomposition process. Sulfur-containing compounds, alcohols and ketones represented the most abundant classes of compounds in both seasons, although almost all 10 compound classes identified contributed to discriminating the stages of decomposition throughout both seasons. The advantages of GC×GC-TOFMS were demonstrated for detecting and identifying trace levels of VOCs, particularly ethers, which are rarely reported as decomposition VOCs.     

Forensic entomology and main challenges in Brazil

Apart from an early case report from China (13th century), the first observations on insects and other arthropods as forensic indicators were documented in Germany and France during mass exhumations in the 1880s by Reinhard, who is considered a co-founder of the discipline. After the French publication of Mégnin's popular book on the applied aspects of forensic entomology, the concept quickly spread to Canada and United States. At that time, researchers recognized that the lack of systematic observations of insects of forensic importance jeopardized their use as indicators of postmortem interval. General advances in insect taxonomy and ecology helped to fill this gap over the following decades. After World Wars, few forensic entomology cases were reported in the scientific literature. From 1960s to the 1980s, Leclercq and Nuorteva were primarily responsible for maintaining the method in Central Europe, reporting isolated cases. Since then, basic research in the USA, Russia and Canada opened the way to the routine use of Entomology in forensic investigations. Identifications of insects associated with human cadavers are relatively few in the literature of the Neotropical region and have received little attention in Brazil. This article brings an overview of historic developments in this field, the recent studies and the main problems and challenges in South America and mainly in Brazil.     

杭州地区猪尸体上昆虫群落的组成 与演替的初步观察

对杭州地区猪尸体的腐败过程及尸体上昆虫群落的演替规律,进行了初步观察和研究。结果表明,室外地表上猪尸体的腐败过程可以划分为新鲜、肿胀、腐烂、干化和残骸5个连续的阶段;常见昆虫包括3目、19科、33种,其中双翅目的巨尾阿丽蝇、丝光绿蝇、南岭绿蝇、大头金蝇、肥须亚麻蝇等为优势种。尸体上昆虫群落的演替有明显的时间规律可循。许多昆虫类群的出现时间与尸体腐败阶段有明确的对应关系,这种对应关系可以为法医科学中推测死后间隔时间(postmortem interval, PMI)提供依据。     

The Identification of Human Remains

The identification of human remains, especially if they have been mutilated or burnt, or occur in skeletal form, may pose a major problem for the forensic physician. It may involve the co-operation of coroner, police officer, forensic pathologist and forensic laboratory. It is first necessary to demonstrate that the remains are human, and that the tissue in question represents one, or more than one, body. A meticulous postmortem examination by the forensic pathologist will reveal all anatomical peculiarities for study and record. Photographs, radiographs, dental charts, fingerprints and blood type all contribute materially to the solution of the problem.     

Characterizing the Smell of Marijuana by Odor Impact of Volatile Compounds: An Application of Simultaneous Chemical and Sensory Analysis

Recent US legislation permitting recreational use of marijuana in certain states brings the use of marijuana odor as probable cause for search and seizure to the forefront of forensic science, once again. This study showed the use of solid-phase microextraction with multidimensional gas chromatography—mass spectrometry and simultaneous human olfaction to characterize the total aroma of marijuana. The application of odor activity analysis offers an explanation as to why high volatile chemical concentration does not equate to most potent odor impact of a certain compound. This suggests that more attention should be focused on highly odorous compounds typically present in low concentrations, such as nonanal, decanol, o-cymene, benzaldehyde, which have more potent odor impact than previously reported marijuana headspace volatiles.     

Fungal volatile organic compounds: A review with emphasis on their biotechnological potential

Fungi produce various mixtures of gas-phase, carbon-based compounds called volatile organic compounds (VOCs) that due to their small size are able to diffuse through the atmosphere and soils. Despite some methodological and technological constraints, researchers have detected and characterized approximately 250 fungal VOCs, many of which have characteristic odors and are produced during primary and secondary metabolism. Fungal VOCs may contribute to a controversial medical diagnosis called “sick building syndrome” and may also be important in the success of some biocontrol species of Trichoderma. VOCs also play important signaling roles for fungi in their natural environments. Many ecological interactions are mediated by VOCs, including those between fungi and plants, arthropods, bacteria, and other fungi. The diverse functions of fungal VOCs can be developed for use in biotechnological applications for biofuel, biocontrol, and mycofumigation. Volatiles represent a new frontier in bioprospecting, and the study of these gas-phase compounds promises the discovery of new products for human exploitation and will generate new hypotheses in fundamental biology.     

Decomposition Odour Profiling in the Air and Soil Surrounding Vertebrate Carrion

Chemical profiling of decomposition odour is conducted in the environmental sciences to detect malodourous target sources in air, water or soil. More recently decomposition odour profiling has been employed in the forensic sciences to generate a profile of the volatile organic compounds (VOCs) produced by decomposed remains. The chemical profile of decomposition odour is still being debated with variations in the VOC profile attributed to the sample collection technique, method of chemical analysis, and environment in which decomposition occurred. To date, little consideration has been given to the partitioning of odour between different matrices and the impact this has on developing an accurate VOC profile. The purpose of this research was to investigate the decomposition odour profile surrounding vertebrate carrion to determine how VOCs partition between soil and air. Four pig carcasses (Sus scrofa domesticus L.) were placed on a soil surface to decompose naturally and their odour profile monitored over a period of two months. Corresponding control sites were also monitored to determine the VOC profile of the surrounding environment. Samples were collected from the soil below and the air (headspace) above the decomposed remains using sorbent tubes and analysed using gas chromatography-mass spectrometry. A total of 249 compounds were identified but only 58 compounds were common to both air and soil samples. This study has demonstrated that soil and air samples produce distinct subsets of VOCs that contribute to the overall decomposition odour. Sample collection from only one matrix will reduce the likelihood of detecting the complete spectrum of VOCs, which further confounds the issue of determining a complete and accurate decomposition odour profile. Confirmation of this profile will enhance the performance of cadaver-detection dogs that are tasked with detecting decomposition odour in both soil and air to locate victim remains.     

药（毒）物对尸食性蝇类生长发育影响的研究进展

药（毒）物对尸食性蝇类生长发育影响是法医昆虫毒理学领域里一个十分重要的研究方向,其研究结果可对与药（毒）物相关死亡案件的死亡时间作出修正。随着近年来全球毒品及药物滥用情况的日趋严重,其所导致的死亡案件也越来越多。这类案件常常需要应用尸食性蝇类生长发育历期来推算死后经历时间（postmortem interval, PMI）。为了阐明该领域的研究进展以及未来研究的焦点和难点,本文在阐述法医昆虫毒理学概念和特点的基础上,按照不同的药（毒）物分类,对近年来药（毒）物对尸食性蝇类生长发育影响在国内外的研究进展进行了综述。研究表明,某些药（毒）物对尸食性蝇类生长发育具有一定的影响,且这种影响存在种属差异。目前,该领域的研究尚限于宏观现象观察阶段,其研究范围在不断拓宽,既有的研究也在进一步深化,但还有许多问题有待进一步探讨。     

Pre-and Postmortem Influences on Brain RNA

Abstract: Many potentially valuable techniques for the understanding of human neurobiological and neuropathological processes require the use of RNA obtained from postmortem tissue. As with earlier neurochemical studies, there are two particular problems posed by such tissue in comparison with tissue from experimental animals. These are the postmortem interval and the condition of the patient prior to death, referred to as the agonal state. We review the nature and extent of the effects of postmortem interval and agonal state on RNA in brain tissue, with particular reference to the study of neuropsychiatric disorders. Perhaps surprisingly, postmortem interval has at most a modest effect on RNA. Abundant intact and biologically active RNA is present in tissue frozen 36 h or more after death. Postmortem interval does not account for the marked variability observed among human brains in all RNA parameters. Despite the overall stability of RNA after death, some evidence suggests that individual RNAs may undergo postmortem decay. Less attention has been paid to the effects of agonal state. The existing data indicate that events in the premortem period such as hypoxia and coma can affect the amount of some messenger RNAs. The nature of agonal state influences depends on the messenger RNA in question, though the basis for this selective vulnerability is unknown. No agonal state effect on overall RNA level or activity has been found. The data show that postmortem brain tissue can be used for RNA research. However, considerable attention must be paid to controlling for the influences of pre-and postmortem factors, especially when quantitative analyses are performed.     

Forensic implication of cadaveric behaviors of the Japanese pavement ant (Tetramorium tsushimae Emery) attending to rabbit cadavers

It is noticed by some researchers that ants may cause some forensic confusion in understanding death scenes. In the aspect of relationship between the ant‐animal decomposition, we observed the behavior of ants congregating on dead animals. Amongst various species of ants visiting dead rabbits, Tetramorium tsushimae Emery was noticeable in producing scratched scars, mounds, and nests around dead rabbits and covering them with soils. The behaviors are likely to interfere or to disturb the usual process of decomposition succession lead by maggots. We discussed that a series of cadaveric behaviors of T. tsushimae may be used as a potential forensic hint not to misunderstand death scenes disturbed by the species.     

呼吸中的疾病诊断标志物及检测技术

人类呼出气体中的各种化合物能提供各种疾病和健康状况的重要信息。近年来,由于红外、电化学、化学发光等新技术的重大突破和质谱仪的使用,使得在极低浓度下精确测量呼出的挥发性有机化合物(VOCs)和气溶胶颗粒成为可能,呼吸检测领域因而取得了重大进展:,呼吸检测因其可以作为一种实时、快速和无创的方法来评估和监测各种疾病与健康状况信息,在科学研究、临床运用中引起了广泛关注。本综述主要概述呼出气体成分分析方法及在疾病诊断中的研究与应用情况,旨在为将来疾病的实时、快速和无创诊断提供一种新的策略.     

The invasive species Alliaria petiolata (garlic mustard) increases soil nutrient availability in northern hardwood-conifer forests

The invasion of non-native plants can alter the diversity and activity of soil microorganisms and nutrient cycling within forests. We used field studies to analyze the impact of a successful invasive groundcover, Alliaria petiolata, on fungal diversity, soil nutrient availability, and pH in five northeastern US forests. We also used laboratory and greenhouse experiments to test three mechanisms by which A. petiolata may alter soil processes: (1) the release of volatile, cyanogenic glucosides from plant tissue; (2) the exudation of plant secondary compounds from roots; and (3) the decomposition of litter. Fungal community composition was significantly different between invaded and uninvaded soils at one site. Compared to uninvaded plots, plots invaded by A. petiolata were consistently and significantly higher in N, P, Ca and Mg availability, and soil pH. In the laboratory, the release of volatile compounds from the leaves of A. petiolata did not significantly alter soil N availability. Similarly, in the greenhouse, the colonization of native soils by A. petiolata roots did not alter soil nutrient cycling, implying that the exudation of secondary compounds has little effect on soil processes. In a leaf litter decomposition experiment, however, green rosette leaves of A. petiolata significantly increased the rate of decomposition of native tree species. The accelerated decomposition of leaf litter from native trees in the presence of A. petiolata rosette leaves shows that the death of these high-nutrient-content leaves stimulates decomposition to a greater extent than any negative effect that secondary compounds may have on the activity of the microbes decomposing the native litter. The results presented here, integrated with recent related studies, suggest that this invasive plant may change soil nutrient availability in such a way as to create a positive feedback between site occupancy and continued proliferation.