Estimation of the time of death: where we are now?

ABSTRACT: One of the increasingly discussed topics in forensic pathology is that concerning the quantification of the postmortem interval (PMI). The estimation of the time interval between the death of a person and the discovery of the body is extremely complicated, as it is affected by the influence of many factors, both endogenous and exogenous. With the advancement of knowledge in the field of molecular biology, several studies have been performed, for more than 30 years, on the degradation pattern of macromolecules, such as proteins, DNA, RNA, and the relationship with PMI. Despite initial enthusiasm, studies have shown different kind of limitations in determining PMI in the forensic field. In the last years, consequently, researchers focused their attention on the potential of microRNAs as housekeeping genes, due to their postmortem stability and resistance to degradation. MiRNAs are small, endogenous, single stranded, non-coding RNA molecules identified in plants, animals and DNA virus transcriptome. Various and growing are the fields of application: to establish time of death, to evaluate vitality of skin lesions, in cases of head trauma, and cases of acute myocardial infarction. Their use could also be particularly useful in determining late PMI (beyond 24 hours after death), as no additional markers are available in this scenario. At the moment, scientific research is still at an early stage as it is mainly based on animal models. However, the promising properties of miRNAs and their low cost may make this field of research very interesting for an increasingly precise determination of PMI in the future.

Effects of salicylates on evoked otoacoustic emissions and remote masking in humans.

The aim of this study was to evaluate, in young volunteer subjects, the effects of salicylates on evoked otoacoustic emissions (EOAEs), which presumably reflect an active mechanical process in the cochlea due to outer hair cell (OHC) activity, and on remote masking (RM), which has been proposed as a useful tool in the study of the non-linear cochlear distortion products generated by high-frequency maskers. Data from the present research are consistent with the literature showing a reversible effect of salicylate leading to elevated hearing thresholds and reduced EOAE amplitudes. From the point of view of new findings, the results demonstrate a reversible effect of salicylates on RM magnitude, which decreases as serum salicylate concentration increases. As described previously by other authors, salicylate selectivity inhibits OHC motility and, in consequence, reduces the amplitude of the motion of the basilar membrane. According to these data it is very likely that the observed reduction in RM magnitude after salicylate administration is also the result of the decreased ability of the OHCs to contract and of the reduced basilar membrane motion. The results are consistent with the conclusion that the OHC system function plays a role in producing RM.