1H NMR analysis of GHB and GBL: further findings on the interconversion and a preliminary report on the analysis of GHB in serum and urine

A 1H nuclear magnetic resonance (1H NMR) method for the determination of gamma-hydroxybutyric acid (GHB) and gamma-hydroxybutyrolactone (GBL) in human serum and urine using spiked samples has been developed. The method gives linear responses (correlation coefficients of 0.99 or greater) over the concentration range 0.01 mg/mL to 4.0 mg/mL in urine and 0.3 mg/mL to 2.0 mg/mL in serum. No sample pretreatment is required. Studies of the chemical interconversion of GBL and GHB showed hydrolysis of GBL to be rapid at pH 11.54, slower and less complete (30% hydrolysis) at pH 2.54 and slowest at pH 7.0, reaching 30% hydrolysis in about 40 days. No esterification of GHB was observed at any pH.     

Postmortem non-invasive virtual autopsy: death by hanging in a car

A body was found behind a car with a noose tied around its neck, the other end of the rope tied to a tree. Apparently the man committed suicide by driving away with the noose tied around his neck and was dragged out of the car through the open hatchback. postmortem multislice-computed tomography (MSCT) and magnetic resonance imaging (MRI) indicated that the cause of death was cerebral hypoxia due to classic strangulation by hanging, and not due to a brainstem lesion because of a hang-man fracture as would be expected in such a dynamic situation. Furthermore, the MRI displayed intramuscular haemorrhage, bleeding into the clavicular insertions of the sternocleidomastoid muscles and subcutaneous neck tissue. We conclude that MSCT and MRI are useful instruments with an increased value compared with 2D radiographs to augment the external findings of bodies when an autopsy is refused. But further postmortem research and comparing validation is needed.     

Empirical analysis of the STR profiles resulting from conceptual mixtures

Samples containing DNA from two or more individuals can be difficult to interpret. Even ascertaining the number of contributors can be challenging and associated uncertainties can have dramatic effects on the interpretation of testing results. Using an FBI genotypes dataset, containing complete genotype information from the 13 Combined DNA Index System (CODIS) loci for 959 individuals, all possible mixtures of three individuals were exhaustively and empirically computed. Allele sharing between pairs of individuals in the original dataset, a randomized dataset and datasets of generated cousins and siblings was evaluated as were the number of loci that were necessary to reliably deduce the number of contributors present in simulated mixtures of four or less contributors. The relatively small number of alleles detectable at most CODIS loci and the fact that some alleles are likely to be shared between individuals within a population can make the maximum number of different alleles observed at any tested loci an unreliable indicator of the maximum number of contributors to a mixed DNA sample. This analysis does not use other data available from the electropherograms (such as peak height or peak area) to estimate the number of contributors to each mixture. As a result, the study represents a worst case analysis of mixture characterization. Within this dataset, approximately 3% of three-person mixtures would be mischaracterized as two-person mixtures and more than 70% of four-person mixtures would be mischaracterized as two- or three-person mixtures using only the maximum number of alleles observed at any tested locus.