Comparative use of aqueous humour 1H NMR metabolomics and potassium concentration for PMI estimation in an animal model

Abstract

Estimation of the post-mortem interval (PMI) remains a matter of concern in the forensic scenario. Traditional and novel approaches are not yet able to fully address this issue, which relies on complex biological phenomena triggered by death. For this purpose, eye compartments may be chosen for experimental studies because they are more resistant to post-mortem modifications. Vitreous humour, in particular, has been extensively investigated, with potassium concentration ([K+]) being the marker that is better correlated with PMI estimation. Recently, a 1H nuclear magnetic resonance (NMR) metabolomic approach based on aqueous humour (AH) from an animal model was proposed for PMI estimation, resulting in a robust and validated regression model. Here we studied the variation in [K+] in the same experimental setup. [K+] was determined through capillary ion analysis (CIA) and a regression analysis was performed. Moreover, it was investigated whether the PMI information related to potassium could improve the metabolome predictive power in estimating the PMI. Interestingly, we found that a part of the metabolomic profile is able to explain most of the information carried by potassium, suggesting that the rise in both potassium and metabolite concentrations relies on a similar biological mechanism. In the first 24-h PMI window, the AH metabolomic profile shows greater predictive power than [K+] behaviour, suggesting its potential use as an additional tool for estimating the time since death.

Post mortem computed tomography meets radiomics: a case series on fractal analysis of post mortem changes in the brain

“…Concerning the determination of the PMI, however, only a few studies that focus on the use of post-mortem CT can be found in the literature. Undoubtedly, in the past years, efforts have been made by the forensic community, including our research team, to identify methods that could help determine the time of death, such as the study of human tissues transcriptomes [29], muscle proteins degradation [30], gene expression patterns [31], ocular changes, [32,33], metabolomics [34][35][36], the study of rigor mortis using ultrasound shear wave elastography (US SWE) [37] or atomic force microscopy (AFM) [38]. However, to our knowledge, there are no studies concerning the application of fractal analysis to post-mortem CT scans for the determination of the PMI.…”

Untargeted metabolomics approaches to improve casework in clinical and forensic toxicology—“Where are we standing and where are we heading?”

“…In an attempt to overcome the ethical issue of time-dependent tissue collection, other matrices were previously proposed to study endogenous postmortem changes. These include anatomically isolated ocular fluids such as vitreous-and aqueous humor (Locci et al, 2019(Locci et al, , 2021. In these, metabolomics changes were found to progress slower and smoother than in blood and were hence proposed as a more suitable matrix for PMI estimation, but still, large enough study sets are missing for reliable PMI estimation (Zelentsova et al, 2020).…”

Application of Micro-Computed Tomography for the Estimation of the Post-Mortem Interval of Human Skeletal Remains

“…Various techniques and methods have been employed to estimate the PMI with the highest accuracy. Methods include examination of the external physical appearance; histopathological surveys [ 6 , 7 , 8 ]; reaction with a mineral acid, reaction with benzidine, nitrogen loss [ 9 ]; molecular biology [ 10 , 11 , 12 , 13 , 14 , 15 ]; metabolomics [ 16 ]; high performance liquid chromatography-tandem mass spectrometry [ 17 ]; UV-Vis spectroscopic methods [ 18 , 19 , 20 , 21 , 22 ]; radioisotope measurements [ 23 , 24 , 25 , 26 ]; luminol chemiluminescent reaction [ 24 , 27 , 28 , 29 , 30 , 31 ]; X-ray diffraction [ 32 , 33 , 34 ]; spectroscopic technology [ 21 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ]; postmortem computed tomography (CT) [ 48 ], micro-CT [ 2 , 34 ]; visible and thermal 3D imaging [ 49 ]; and entomological methods (succession model, carrion insect development) ...…”