RESUMO
BACKGROUND: The unambiguous diagnosis of asphyxiation is still a major challenge for the forensic pathologist, especially in terms of highly advanced decomposed corps. METHODOLOGY: In order to demonstrate asphyxiation particularly in profoundly putrid bodies we hypothesized that hypoxic stress is basically responsible for generalized fatty degeneration of visceral organs which can be detected by histological examination using a special staining technique referred to as Oil-Red-O Stain (Sudan III-red-B-stain). To test this hypothesis we examined different tissues (myocardium, liver, lung and kidney) of 107 people divided into 5 groups. These are: (i) 71 case-victims who were found in a truck and died most likely due to asphyxiation, whereby any other violent or natural cause of death was ruled out by postmortem examination; (ii) 10 barely decomposed positive-control-victims; (iii) 6 non-decomposed positive-control-victims; iv) 10 drowning non-decomposed positive-control victims, and v) 10 negative-control-victims. Apart from general histological special staining methods, an immunohistochemically approach as a case-control-study on lung tissues of same individuals was carried out by means of using two polyclonal rabbit-antibodies against (i) HIF-1-α (Hypoxia Inducing Factor-1 alpha) and (ii) SP-A (pulmonary surfactant-associated protein A) to detect both the transcription factor and pulmonary surfactants. The positive proof of already either of them gives evidence of death caused by hypoxia. RESULTS: Histological examination of myocardium, liver and kidney of the 71 case-victims and the 10 positive-control-victims using Oil-Red-O Stain showed a fatty degeneration of small droplet type; there was no evidence for fatty degeneration in tissues of the 10 negative-control-victims. These findings strongly indicate a causal association between oxygen deficiency and generalized fatty degeneration of viscera due to insufficient oxygen supply. In terms of methodology, this special staining technique seems to be very informative, even applicable on decomposed corps. Results of immunohistochemistry indicate that on the one hand the detection of HIF-1α is not possible to perform on (advanced) putrid bodies, whereas the verification of SP-A is still feasible on the other. CONCLUSION: Positive Oil-Red-O staining and the immunohistochemical detection of SP-A can serve as a serious hint for the diagnosis of asphyxia on putrid corpses, considering other circumstances of death that have been determined.
