Capillary zone electrophoresis and artificial neural networks for estimation of the post-mortem interval (PMI) using electrolytes measurements in human vitreous humour

Abstract

Determination of electrolyte concentrations (mainly potassium) in vitreous humour has long been considered an important tool in human death investigations for the estimation of the post-mortem interval (PMI). On the basis of its well known potential in ion analysis, capillary zone electrophoresis (CZE) has recently been applied to achieve a rapid and simultaneous determination of inorganic ions in this extracellular fluid. In the present work, artificial neural networks (ANN) were applied for modelling of the relationship of multicomponent CZE analysis of K+, NH4+, Na+, and Ba2+ ions in vitreous humour with PMI. In a study based on 61 cases with different causes of death and a known PMI ranging from 3 to 144 h, the use of ANNs considering all inorganic ion data from the human vitreous humour, achieved a substantial improvement of post-mortem interval prediction. Good linear correlation was observed (r2 = 0.98) and in comparison to the traditional linear least squares (LLS) method applied only to K+ levels in the vitreous humour, the prediction of PMI with ANN was improved by a factor of 5 from approximately +/- 15 h to less than 3 h.

Comparative study of two vitreous humor sampling methods in rabbits

“…In contrast, the ratios of the cases with variations 15 % greater the mean values in the group B (for the first time samples) are 0/9, 0/9, 1/9, 0/9 and 2/9, respectively. Interestingly, our results are consistent with other reports in which entire-sampling showed obvious variations [2][3][4] and micro-sampling yielded less variations [5,6] . This suggests that the micro-sampling methodology is more reliable than one-time entire sampling, and can yield consistent results.…”

“…In contrast, several other reports [5,6] suggested that the two-eye variations are acceptable and they believed that the humor of either eye is representative of the individual.…”

Determination of the early time of death by computerized image analysis of DNA degradation: Which is the best quantitative indicator of DNA degradation?

“…AOD, IOD and AG can sensitively and objectively reflect the DNA content from different perspectives, but AG works best as a quantitative index for the estimation of PMI. This study about CIAT is still preliminary and studies involving multiple factors (such as death mechanisms, environmental temperature etc) are needed to ensure the better consistence and accuracy of the method [22,23] . …”

Recent advances and trends in capillary electrophoresis of inorganic ions

“…More specifically, summaries of practical contributions in which the application format of CE was miniaturized down to a single-cell level [199] and metal ions of clinical significance were involved [200] have recently become available. The most recent real-world application reports, incorporating robust sample preparation procedures, addressed the determination of common alkali, alkaline earth metal, and ammonium ions in urine [201], human plaque fluid [202], and infusion solutions [57], potassium and other cations in vitreous humor [203,204], K, Na, Mg, Ca in lettuce [205], monitoring of the releasing rates of inorganic cations and anions from pine needles [206], the quantification of anions in saliva [163], thiocyanate in different biofluids [207], measuring the nitrate level in various tissue homogenates [208] and concentrations of Cl , SO 4 2-in plant tissue extracts [186] or from microbial fermentation process liquids [209]. Also, the content of iron or zinc dithiocarbamate fungicides in wheat grains [135,210] and of different metal chelates of nitrilotriacetic acid and EDTA in complex nutrient media [211] can be quantified using CE.…”