Postmortem chondrocyte viability in porcine articular cartilage: Influence of time, temperature, and burial under winter conditions

The aim of the present study was to investigate the effects of time, temperature, and burial in a natural environment on the viability of chondrocytes in porcine femoral condyles using confocal laser scanning microscopy. Hind trotters from 10 pigs were buried or left unburied. Samples were collected daily and stained with a combination of vital dyes (calcein-AM and ethidium homodimer-1). The chondrocytes showed an intense staining corresponding to their vitality. In the first 3 days, viability decreased slowly and showed no statistical difference between buried and unburied samples. After the first 3 days, it decreased rapidly, with the viability of the buried samples being 66% on day 4, decreasing to 25% on day 8 and to 16% on day 10, while in the unburied samples it decreased to 43% on day 4, 13% on day 8 and 5% on day 10. Our results indicate a time, temperature, and burial dependent decrease in chondrocyte viability and suggest the use of chondrocyte viability as a marker for estimating PMI in both the natural environment and in animals, as well as its potential use in humans.

Evaluation of porcine decomposition and total body score (TBS) in a central European temperate forest

The total body score (TBS) is a visual scoring method to scale the succession of decomposition stages. It compares decomposition between cadavers, to connect it with external taphonomic factors and estimate the post-mortem interval. To study decomposition in various climatic environments, pigs are often used as human proxies. Currently, there is one TBS system by Keough et al. (J Forensic Sci. 2017;62:986) for surface-deposited domestic pigs, coming from South Africa. Our study aims to evaluate this method and analyze porcine decomposition in Central Europe to inform forensic research and casework. We conducted an experiment studying six 50 kg pig carcasses in a temperate Swiss forest. Three observers documented decomposition patterns and rated the decomposition stages from photographs based on the porcine TBS model by Keough et al. (J Forensic Sci. 2017;62:986). We documented discrepancies between the carcass decomposition of our specimens and those in the South African study, especially related to the high insect activity in our experiment. Furthermore, we noted factors complicating TBS scoring, including rainfall and scavengers. The agreement between TBS observers from photographs was in the highest agreement category apart from one "substantial agreement" category. Our study is the first in Europe to systematically test the Keough et al. (J Forensic Sci. 2017;62:986) method. The results evidence that regional adaptations are required to be applicable for other environments. We present a modified approach based on experimental observations in a Swiss temperate forest. The identification of regional decomposition patterns and drivers will inform future taphonomy research as well as forensic casework in comparable contexts in Central Europe.

Comparative analysis of fetal pig decomposition processes in burials of variable depths and wrapping

This research examined the effects that the variables of burial depth and presence of plastic wrapping had on the decomposition rate of fetal pig (Sus scrofa) remains in a New England environment. The decomposition of 56 fetal pigs was observed in four independent variable groups: 20 cm depth unwrapped, 20 cm wrapped, 60 cm unwrapped, and 60 cm wrapped, with exhumation at months 1, 2, 3, 6, 9, 12, and 18. The authors hypothesized that the rate of decay would be slower for wrapped remains and/or for remains at a greater burial depth. Analysis of these remains consisted of preburial and postburial mass, adipocere coverage, skeletal exposure, and decomposition quantified as Total Body Score (TBS). The difference between preburial and postburial mass was reported as a loss percentage to account for varying preburial masses. Wrapping was a significant influencer of mass loss percentage, with p = 0.0298 but not for the TBS, with p = 0.17565. Burial depth did not have a significant effect on either mass loss percentage or TBS, with p = 0.1956 and 0.08969, respectively. This study suggests that wrapping has a greater influence on decomposition patterns than burial depth in this environment, particularly the mass loss percentage. It is suggested that there are limitations with the use of TBS in Postmortem Interval (PMI) estimation, such as variable burial conditions and body characteristics.

The Application of Metabolomics in Forensic Science with Focus on Forensic Toxicology and Time-of-Death Estimation

Recently, the diagnostic methods used by scientists in forensic examinations have enormously expanded. Metabolomics provides an important contribution to analytical method development. The main purpose of this review was to investigate and summarize the most recent applications of metabolomics in forensic science. The primary research method was an extensive review of available international literature in PubMed. The keywords “forensic” and “metabolomics” were used as search criteria for the PubMed database scan. Most authors emphasized the analysis of different biological sample types using chromatography methods. The presented review is a summary of recently published implementations of metabolomics in forensic science and types of biological material used and techniques applied. Possible opportunities for valuable metabolomics’ applications are discussed to emphasize the essential necessities resulting in numerous nontargeted metabolomics’ assays.

Cell Death-Associated Ribosomal RNA Cleavage in Postmortem Tissues and Its Forensic Applications

Estimation of postmortem interval (PMI) is a key issue in the field of forensic pathology. With the availability of quantitative analysis of RNA levels in postmortem tissues, several studies have assessed the postmortem degradation of constitutively expressed RNA species to estimate PMI. However, conventional RNA quantification as well as biochemical and physiological changes employed thus far have limitations related to standardization or normalization. The present study focuses on an interesting feature of the subdomains of certain RNA species, in which they are site-specifically cleaved during apoptotic cell death. We found that the D8 divergent domain of ribosomal RNA (rRNA) bearing cell death-related cleavage sites was rapidly removed during postmortem RNA degradation. In contrast to the fragile domain, the 5' terminal region of 28S rRNA was remarkably stable during the postmortem period. Importantly, the differences in the degradation rates between the two domains in mammalian 28S rRNA were highly proportional to increasing PMI with a significant linear correlation observed in mice as well as human autopsy tissues. In conclusion, we demonstrate that comparison of the degradation rates between domains of a single RNA species provides quantitative information on postmortem degradation states, which can be applied for the estimation of PMI.

Estimation of postmortem interval using vitreous potassium levels in cases of fatal road traffic collision

AIM OF THE STUDY

To produce a formula that can accurately predict postmortem interval (PMI) based on vitreous potassium levels using road traffic collision fatalities.

MATERIAL AND METHODS

Vitreous humour samples were taken from 78 individuals who had died following road traffic collisions between 2010 and 2015. Samples were obtained from both eyes and were sent for on-site analysis. Measurement of potassium was by an indirect ion-specific electrode Siemens diagnostics ADVIA 2400 chemistry system. Exact time of death was known from police reports, the time of postmortem was recorded and the postmortem interval was calculated. Linear regression was then used to analyse the relationship between the two. The impact of age was also assessed.

RESULTS

PMI was between 6 and 162 hours. As vitreous potassium increases, the PMI also increases; exhibiting a linear relationship. This is illustrated by a regression equation of PMI = 6.42[K+] - 40.94, R = 0.67 (p < 0.001). This produced a formula closely comparable with three other studies proposed in previous literature and produces estimates that may exceed one calendar day. When both age and medical intervention are accounted for there is an insignificant improvement in prediction.

CONCLUSIONS

Validated methods have been used to produce a formula for prediction of PMI using vitreous potassium. Although this is specific to road traffic collisions, the methods are transferable and can be seen to be comparable with other recently published methods. Nonetheless, if greater levels of accuracy are required it is suggested that biomarkers delivering a higher level of precision should still be sought.