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.

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The effects of alcohol intake on haemodynamics and heart rate variability were investigated with relation to genotypes of aldehyde dehydrogenase 2 (ALDH2), which were determined in 33 male Japanese volunteers (mean +/- s.e., 35.7 +/- 1.4 years) using the PCR-RFLP method. On the alcohol intake day, they consumed 660 ml of beer containing 33 ml of ethanol (0.3-0.5 g/kg of body weight) from 18.00 to 18.30. On the control day, they ingested the same amount of non-alcoholic beer. Ambulatory blood pressure, heart rate, and ECG R-R intervals were measured during a 24-h period with a portable recorder. A power spectral analysis of R-R intervals was performed to obtain the low-frequency (LF) and high-frequency (HF) components. Sixteen subjects were homozygotes for the normal ALDH gene (active ALDH2), only one was a homozygote for the mutant ALDH2 gene (inactive ALDH2), and the remaining 16 were heterozygotes (inactive ALDH2). Alcohol intake did not change 24-h average blood pressure (BP) either in the active ALDH2 group or in the inactive ALDH2 group. However, during the time interval from 18.30 to 0.00, alcohol intake significantly decreased diastolic BP in the active ALDH2 group and both systolic and diastolic BPs in the inactive ALDH2 group. In the active ALDH2 group, alcohol intake did not change heart rate, while in the inactive ALDH2 group, alcohol intake significantly increased 24-h average heart rate by 5.3 +/- 1.6 beats per minute (P < 0.01). In the active ALDH2 group, neither the LF nor the HF component was changed by alcohol intake, while in the inactive ALDH2 group, both the LF and the HF components were significantly decreased during the time interval from 18.30 to 0.00. These results demonstrate for the first time that ALDH2 genotypes modify the effects of intake of a small amount of alcohol on haemodynamics and heart rate variability in Japanese men.

In vivo and in vitro experiments showed that the -360G allele has lower basal transcriptional activity than the -360A allele, whereas acetaldehyde/ethanol-induced gene expression, in general, seems to be more enhanced in individuals homozygous for the -360G allele than in those with the -360A allele. Thus, the promoter polymorphism may be involved in individual differences in acetaldehyde elimination.