Investigación bioquímica y aproximación proteómica de fluidos biológicos en muertes por sumersión

Resum

Drowning deaths have increased worldwide to become the second cause of unintentional death. Therefore, its diagnosis in forensic pathology is a challenge for our daily practice since the absence of specific and absolutely reliable diagnostic test causes requires complementary examinations to the medical-legal autopsy, such as histopathological, biological and biochemical investigations to identify the cause of death, due to the judicial implications present. Consequently, advances in the research of trace element analysis in biological fluids and in immersion means as well as the study of proteins with differential expression in drowning deaths would contribute to the postmortem diagnosis of drowning. Our objectives were analyzing concentrations of trace elements in blood and in vitreous humor in drowning cases among other causes of death, as well as investigating for the first time the proteomic profile of drowning cases so as to enhance our knowledge of their physiopathology and their possible application in the diagnosis and treatment in survival cases. Material and methods: The sample consisted of 137 bodies (n=111 drowning cases and n=26 cases of other causes of death) whose autopsies were performed at the Institute of Legal Medicine and Forensic Sciences of Spain. The average age of the subjects was 48.58 years and the average post-mortem interval was 27.87 hours. In all case, blood samples were obtained from both ventricles and peripheral and vitreous humor. More specifically, regarding drowning cases, water was collected from the scene. We analyzed lithium, potassium, magnesium, bromine, boron, calcium and strontium in each sample by means of ICP-MS techniques. Concerning proteomic analysis, we identified expresión proteins that coul act as potential biomarkers in the post-mortem diagnosis of drowning through the application of Mass Spectrometry based technologies. Additionally we carried out a pilot proteomic experiment including two drownings and two forensic control cases, validated in 25 cases, with apolipoprotein A and ?-1 antitrypsin determination. Results: The analysis of differences in blood element concentrations in drowning deathsrevealed a higher concentration in all elements but potassium along with higher concentrations at the left ventricle level. With regards to vitreous humor, high concentrations were also found in all elements in drowning cases except for calcium. Furthermore, correlation between blood, vitreous and water was evidenced for lithium, calcium and streontium. No relationship between postmortem interval and trace elements in blood or vitreous humor was found in drowning deaths. The ROC curves showed the higher discrimination capacity for strontium, lithium and magnesium concentrations in blood; otherwise, in vitreous humor it was found for strontium, lithium, boron, bromine and magnesium concentrations. The multivariate analysis revealed strontium and bromine concentrations in the left ventricle and boron in peripheral blood as predictive factors in drowning death. On the other hand, in vitreous humor bromine was revealed as the first factor associated to drowning death. Both apolipoprotein A1 and ?-1 antitrypsin are independent predictors of drowning death. The, we showed significant correlations between concentrations of elements in blood and vitreous humor. The proteomic pilot study reveals that both apolipoprotein A1 and ?-1 antitrypsin are independent predictors of drowning deaths. Conclusions: The joint determination of trace elements in blood and vitreous humor together with the proteomic determination of apolipoprotein A1 and ?-1 antitrypsin would contribute as complementary tests to the diagnosis of seawater drowning deaths.