The aim of the present study was to review the immunohistochemical and biochemical findings with reference to the causes of death in routine casework (total, n = 492). In the immunohistochemistry (n = 283), an increase in intra-alveolar granular SP-A (SP-A score) was often observed in asphyxiation (n = 21/34, 61.8%) and freshwater drowning (n = 15/24, 62.5%), and also in fire and methamphetamine (MA) fatalities (n = 22/76, 28.9% and n = 5/16, 31.3%). Serum SP-A level (n = 134) was elevated in acute respiratory distress syndrome and in some cases of drowning, fire and MA fatalities, hyperthermia and chest traumas. A quantitative analysis of SP-A subclass-gene expression (SP-A1/A2 mRNA) in the lung tissue specimens (n = 126) revealed an increase in the SP-A1/A2 mRNA ratio in asphyxiation (n = 17/21, 80.9%), freshwater drowning (n = 7/9, 77.7%), fire and MA fatalities (n = 20/35, 57.1% and n = 8/10, 80.0%). These findings suggested the usefulness of SP-A as a marker of asphyxiation, respiratory distress and alveolar injury.
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