Caracterización del pulmón como órgano diana de la muerte por sumersiónevaluación del estrés oxidativo y concentraciones de elementos traza

Abstract

The diagnosing of drowning remains one of the most difficult and controversial deaths to establish. It represents one of the leading causes of unintentional death worldwide. In most cases, the forensic pathologist needs not only autopsy findings, but also a series of complementary tests such as histopathological, biological and chemical studies to reach an accurate diagnosis, biological and chemical studies. Although the lung is the most affected organ in death by drowning, there is little information on the impact of this type of death on this organ. The objectives of our work were to investigate the concentration of trace elements in the lungs of subjects who had died from different causes of death in order to evaluate the discriminatory capacity of trace elements in the diagnosing of death by seawater drowning. And to know the processes of oxidative stress in deaths by seawater drowning and other causes of death, analyzing the levels of oxidative stress markers (MDA and GSH) in lung lobes, as well as their correlation with alterations in the immunohistochemical expression of protein A of the pulmonary surfactant. Materials and methods: A total of 11 trace elements in 74 forensic cases were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Scanning electron microscopy associated with energy dispersive X-ray spectroscopy was used to identify ultrastructural alterations and determine the levels of trace elements in the lung samples. On the other hand, we studied in a series of 93 forensic autopsy cases, oxidative stress markers by colorimetric determination of Malondialdehyde (MDA), by spectrophotometry of GSH (Tiztze method). Finally, to evaluate the immunohistochemical expression of PS-A, histological analyses were performed using the mouse monoclonal anti-human PS-A antibody PE-10. Results: Significantly higher concentrations of Br and Sr, and significantly lower concentrations of Cu, Zn, Se, Cd and Pb were obtained in cases of death by seawater drowning compared to other causes of death. These results were confirmed by PCA, which revealed a wide separation between drowning deaths and all other causes of death. MDA levels were higher in both lungs in cases of death by seawater drowning compared to other causes of death, with statistically significant differences in MDA concentrations between the three groups of causes of death analyzed. Similarly, significantly higher levels of GSH were observed in cases of drowning compared to the other causes of death, being more significant in the right lung. Higher immunohistochemical expression of SP-A was obtained in cases of seawater drowning than in the other causes of death, with higher levels in both lungs. In the correlation analysis between the levels of oxidative stress (MDA and GSH) in lung tissue and the level of SP-A expression, positive and significant results were obtained for the cases of seawater drowning, both in the alveolar membrane and in the alveolar space. Conclusions: The determination of the trace elements Br and Sr in lung together with the determination of MDA and GSH levels in lung tissue, as well as the level of SP-A expression can be of great importance in the diagnosing of death by seawater drowning and circumstances of death. A better understanding of the physiology of drowning is important for its potential implications in taking action in the management of patients who have survived a drowning process and also crucial in forensic pathology for a more correct interpretation of the events leading to death by drowning.