A preliminary study on postmortem interval estimation of suffocated rats by GC-MS/MS-based plasma metabolic profiling

Abstract

Estimation of postmortem interval (PMI) is an important goal in judicial autopsy. Although many approaches can estimate PMI through physical findings and biochemical tests, accurate PMI calculation by these conventional methods remains difficult because PMI is readily affected by surrounding conditions, such as ambient temperature and humidity. In this study, Sprague-Dawley (SD) rats (10 weeks) were sacrificed by suffocation, and blood was collected by dissection at various time intervals (0, 3, 6, 12, 24, and 48 h; n = 6) after death. A total of 70 endogenous metabolites were detected in plasma by gas chromatography-tandem mass spectrometry (GC-MS/MS). Each time group was separated from each other on the principal component analysis (PCA) score plot, suggesting that the various endogenous metabolites changed with time after death. To prepare a prediction model of a PMI, a partial least squares (or projection to latent structure, PLS) regression model was constructed using the levels of significantly different metabolites determined by variable importance in the projection (VIP) score and the Kruskal-Wallis test (P < 0.05). Because the constructed PLS regression model could successfully predict each PMI, this model was validated with another validation set (n = 3). In conclusion, plasma metabolic profiling demonstrated its ability to successfully estimate PMI under a certain condition. This result can be considered to be the first step for using the metabolomics method in future forensic casework.

MALDI-TOF MS as a Novel Tool for the Estimation of Postmortem Interval in Liver Tissue Samples

“…These signs continue to be the main basis for estimating the PMI 1 . For many years, various approaches have been used to determine the PMI, including examinations of thanatochemistry 2, 3 , DNA/RNA degradation 4, 5 , and forensic entomology 6, 7 .…”

“…The physical changes that occur after death, including the cooling of the body, rigor mortis, and the development of lividity, have long been recognized as early postmortem phenomena 1 . These signs continue to be the main basis for estimating the PMI 1 .…”

“…However, these methods estimate the postmortem interval using a few—or even just one—specific parameters, and their precision and time-frame of applicability are often limited. In recent years, studies of postmortem microbial communities 8–11 , and postmortem metabolomics/lipidomics 1, 12, 13 , have emerged, and have been successfully applied to PMI estimation. These technologies may be a potential tool for PMI estimation in forensic practice.…”

Potential use of GAPDH m-RNA in estimating PMI in brain tissue of albino rats at different environmental conditions

“…Since decades, many methods have been used to determine the PMI including physical, biochemical and entomological methods (Sato et al, 2015). The earliest changes after death (within the first 24 h postmortem) include the development and regression of rigor mortis, the progression of livor mortis and algor mortis.…”

Vitality and wound-age estimation in forensic pathology: review and future prospects

“…Metabolomics, which involves assaying all low-molecular-weight biochemicals, is used for diagnosing disease, investigating pathogenic mechanisms, and determining prognoses. Metabolic profiling is useful for estimating the postmortem time interval [54,55], but its suitability for determining wound age is unclear. Therefore, assessing changes in factors at various levels of wound healing could enable identification of the biomarkers that would allow us to determine the time of the injury.…”