Master of Arts (MA)
Geography and Anthropology
There are numerous ways to estimate postmortem interval (PMI), or time since death, including body temperature, rigor mortis, insect activity, and decomposition. Individually, many of these indicators are prone to inaccuracy due to the influence of the external environment upon them. This study proposed that in addition to or in conjunction with these and other indicators, certain enzymes could be used to accurately determine PMI, namely aspartate aminotransferase (AST), alcohol dehydrogenase (ADH), creatine kinase (CK), and lactate dehydrogenase (LDH). In this project, 18 rats were studied postmortem to determine how ethanol consumption and different environments affect decomposition and enzyme activity. Three groups of six rats each were studied at three different times. Two rats in each group of six received Treatment 1 (0 mg/dL ethanol), two received Treatment 2 (75 mg/dL ethanol), and two received Treatment 3 (200 mg/dL ethanol). One hour after treatments were given, the rats were euthanized in a CO2 chamber. After euthanasia one rat from each treatment pair was put into a cold room (approximately 40° F) and the other was put outside. Liver tissue, cardiac muscle, and skeletal muscle samples were taken periodically and frozen at -80° C. Samples were homogenized and centrifuged at 12x g for one hour and put back into -80° C until analysis on the spectrophotometer. After this analysis, the data were compiled using the SAS/IML version 9.1 program. Graphs for each enzyme and tissue type were made, illustrating the positions of all data points in relation to the prediction interval deduced from the statistical computations. Visually and statistically, the graphs did not seem to exhibit any discernible pattern with regard to enzyme velocity. Alcohol did not appear to affect the enzyme activity. This study did not find a pattern for using enzyme velocity to determine PMI. Further research projects could attempt to study other variables not considered in this project. Studies using larger animals, different environments, and different taphonomic conditions would all be projects that could enhance this subfield of forensics.
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Buras, Karly Laine, "Are enzymes accurate indicators of postmortem interval?: a biochemical analysis" (2006). LSU Master's Theses. 177.