الفهرس 
List of tablesOnly 14 pages are availabe for public view
 |  | from | 93 |  |  |
| | | from | 93 | | |
Abstract
The postmortem interval (PMI) is a significant step in most homicidal or unattended death investigations. It remains one of the most challenging variables to measure and establish, despite the large number of researches undertaken.
The present study is an experimental study. It was performed to evaluate the role of different methods in estimation of postmortem interval (PMI) by studying: biochemical changes in blood (uric acid, lactate, amylase enzyme, lipase enzyme and insulin) and histopathological changes in tongue, salivary glands and pancreas.
The study was conducted on 48 adult Albino rats weighting about 100-200 gm. The ethics and husbandry conditions of animal research were considered according to the guide of care and use of laboratory animals approved by Medical Research Ethics Committee of Faculty of Medicine, Sohag University.
The rats were divided randomly into 8 groups (6 rats each) according to different postmortem intervals.
• group I (0 hour postmortem): for studying postmortem changes at 0 hours postmortem.
• group II (2 hours postmortem): for studying postmortem changes at 2 hours postmortem.
• group III (4 hours postmortem): For studying postmortem changes at 4 hours postmortem.
• group IV (8 hours postmortem): For studying postmortem changes at 8 hours postmortem.
• group V (16 hours postmortem): For studying postmortem changes at 16 hours postmortem.
• group VI (24 hours postmortem): For studying postmortem changes at 24 hours postmortem.
• group VII (36 hours postmortem): For studying postmortem changes at 36 hours postmortem.
• group VIII (48 hours postmortem): For studying postmortem changes at 48 hours postmortem.
All animals were sacrificed by cervical dislocation under light anesthesia by ether inhalation at the beginning of the study. The blood was drawn via cardiac puncture and placed into a 5 ml ethylene diamine tetra acetic acid (EDTA) collection tube using 5ml syringe for further assessment at different postmortem intervals. Tongue, salivary glands and pancreas were excised and placed in 10% formalin solution at the different postmortem intervals of the study. Then put in paraffin wax according to the standard procedures and stained by H&E for histopathological examination
The data obtained were analyzed statistically using SPSS version (17.0).
Biochemical results:
There was significant statistical increase in the mean value of serum uric acid occurred 36 hours after death (group VII).
Also, there was significant statistical increase in the mean value of serum lactate occurred 8 hours after death (group IV) and continue to increase with increasing PMI.
There was significant statistical increase in the mean value of serum lipase enzyme occurred 36 hours after death (group VII).
There was no significant statistical change in the mean value of serum amylase enzyme and insulin with increasing postmortem interval.
There was strong positive correlation between serum lactate, lipase enzyme and PMI. Serum uric acid showed a moderate positive correlation with PMI. There was a negligable positive correlation between serum amylase enzyme and PMI. There was non-significant correlation between insulin and PMI.
A regression formula was obtained to predict PMI from serum lactate and lipase enzyme.
PMI = -16.395 + 1.482 (serum lactate) + 0.136 (serum lipase enzyme).
Histopathological results
In the present study histopathological examination of tongue tissue at different postmortem intervals showed the following changes: There was epithelial shredding and spliting in the tongue tissue and cytoplasmic eosinophilia. With increasing postmortem interval there were cytoplasmic vacuolation, karyolysis, pyknosis and karyorrhexis throughout the epithelium. Also, there was muscle degenration.
Histopathological examination of salivary gland at (0) hour postmortem showed normal serous acini architecture, normal striated ducts, no cellular or nuclear changes in acini or ducts with normal CT distribution. With increasing postmortem interval there were vacuolation, pykinosis and karyolysis of acinar cells. After (48) hours, there were distortion of acinar architecture, CT homogenization and inflammatory cellular infiltration.
Histopathological examination of pancreas at different postmortem intervals showed the following changes: Pancreatic acini appeared at first slightly vacuolated then with increasing postmortem interval they appeared with dark nuclei and with nuclear ghosts (karyolysis). Also, islets of Langerhans were visible at first and formed by acidophilic cells and basophilic cells and with increasing postmortem interval they appeared with dark nuclei and nuclear ghosts.
Conclusion:
There were increase in serum uric acid and lipase enzyme started 36 hours after death. Also, there was increase in serum lactate started 8 hours after death and it continued to rise until 48 hours after death.
It has been found that serum lactate and lipase enzyme could be used to determine postmortem interval through the regression equation: PMI= -16.395 + 1.482 (serum lactate) +
0.136 (serum lipase enzyme).
Also, histopathological examination of tongue, salivary glands and pancreas showed valuable results concerning PMI estimation.
Recommendation
• The present study detected that there was increase in serum lactate started 8 hours after death and it continued to rise until 48 hours after death. So it is recommended to use this biochemical marker to estimate postmortem interval.
• It has been found that serum lactate and lipase enzyme could be used to determine postmortem interval through the regression equation: PMI= -16.395 + 1.482 (serum lactate) + 0.136 (serum lipase enzyme). Therefore, it is recommended to use this equation to determine postmortem interval.
• It is recommended to perform further studies to evaluate other biochemical markers and to assess its accuracy in determining postmortem interval.
• It is recommended to use histopathological examination of tongue, salivary glands and pancreas as they showed valuable results concerning PMI estimation.
• Also, further studies should be performed to detect the accessibility of estimating postmortem interval from histopathological examination of different body organs.
• More researches are needed to be conducted at different environmental conditions to assess its effect on PMI as temperature and humidity.
• It is recommended to perform more studies for a longer postmortem interval (more than 48 hours).
• Important results were achieved from this animal study. So, it is recommended to be conducted on human.
• More studies should take in consideration the factors which influence postmortem autolytic changes such as manner and cause of death.