Journal of Forensic Research

Immunohistochemical Characterization of Sudden Death While Bathing:Evaluating the Expression of SP-A, HSP70 and c-Fos Following Drowning and Thermal Stress

Abstract

Makoto Sakurada, Migiwa Asano, Azumi Kuse, Mai Morichika, Kanako Nakagawa and Yasuhiro Ueno

Sudden death while bathing is a major issue in elderly Japanese individuals. Despite its growing incidence, the exact processes underlying sudden death while bathing remain unknown. This study was designed to establish reliable diagnostic markers for drowning while bathing, as well as to assess the pathological conditions associated with sudden death while bathing, by analyzing the immunohistochemical intensity and localization of surfactant protein-A (SP-A), heat shock protein 70 (HSP70) and c-Fos protein in the lungs and central nervous system, including the cerebral cortex and hippocampus. We found that a distinct pattern of immunohistochemical expression of SP-A, HSP70 and c-Fos in the lung can be utilized to diagnose drowning. In most of these individuals, c-Fos protein was
absent from the central nervous system, providing insight into patterns of ischemia in the central nervous system, or a loss in consciousness while bathing. We also found that rapid hypothermia or a cold stimulus increased c-Fos expression in the hippocampus (CA4). Furthermore, our results suggest that HSP70 expression in the hippocampus (CA4) can be used to estimate the length of time between the initial occurrence of stress and death.