Relation between PMI and FTIR spectral changes in asphyxiated rat's liver and spleen / 法医学杂志

OBJECTIVE@#Fourier transform infrared (FTIR) spectroscopy was applied to observe the postmortem degradation process in mechanical asphyxiated rat's liver and spleen for providing a new method of estimating PMI.@*METHODS@#Rats were sacrificed by mechanical asphyxia and cadavers were kept at (20 +/- 2) degrees C in a control chamber. The liver and spleen were sub-sampled from the same rat at intervals of 0-15 days postmortem and the data were measured by FTIR spectrometer. The different absorbance (A) ratios of peaks were calculated and the curve estimation analysis between absorbance ratios (x) and PMI (y) were performed to establish mathematical models by the statistical software.@*RESULTS@#The band absorbance ratios showed increase, decrease and stable with PMI. The cubic model functions showed the strongest correlation coefficient. Compared with the spleen, the liver showed a higher correlation coefficient. The A1541/A1396 of liver showed the highest correlation coefficient (r=0.966). After 6-7 days postmortem, band absorbance ratios showed a steady period.@*CONCLUSION@#FTIR spectroscopy can be a new and efficient method to estimate PMI within 7 days.

Relationship between PMI and fourier transform infrared spectral changes in muscle of rats after death caused by mechanical asphyxial / 法医学杂志

OBJECTIVE@#To observe the postmortem degradation process in rat myocardium and skeletal muscle using Fourier transform infrared (FTIR) spectroscopy and to provide a new method for estimating postmortem interval (PMI).@*METHODS@#Left ventricle and skeletal muscles of rats dying of mechanical asphyxiated were sampled at different PMIs. The changes of different chemical functional group in the myocardium and skeletal muscle samples were measured by FTIR spectroscopy. The different absorbance (A) ratios of peaks were calculated and the curve estimation analysis between absorbance ratios (x) and PMI (y) were performed to establish six mathematical models.@*RESULTS@#FTIR spectral absorption peak of rat myocardium and skeletal muscle showed three changes: increase, decrease and stable. The cubic model function showed the strongest correlation coefficient. The A1080/A1396 ratio of skeletal muscle showed the strongest correlation coefficient (r = 0.832) with more accurate determination of PMI.@*CONCLUSION@#FYIR spectroscopy can be potentially used as an effective method for estimating PMI in forensic practice using myocardium and skeletal muscle.

Postmortem changes of liver phosphofructokinase-2 level in rats following different causes of death / 法医学杂志

OBJECTIVE@#To study the changes of liver phosphofructokinase-2 (PFK-2) level at different postmortem intervals as well as due to different causes of death.@*METHODS@#One hundred and five rats were randomly divided into 3 groups and the rats were sacrificed by either bleeding, suffocating, and neck breaking, respectively. The content of liver PFK-2 at 0, 1, 2, 4, 8, 12 and 24 hours following death were studied using immunohistochemishtry and image analysis.@*RESULTS@#PFK-2 content of the rat's liver in all 3 groups showed a linear decrease at different postmortem intervals with no significant statistical differences found between the different groups.@*CONCLUSION@#PFK-2 level in rat liver appears to decrease linearly in correlation with prolonged PMI.

Induction of hypoxia-inducible factor-1alpha in two kinds of rats asphyxiation death models / 法医学杂志

OBJECTIVE@#To investigate the expression of hypoxia-inducible factor 1-alpha (HIF1-alpha) in the heart, lung, liver and kidney in rats died of two typical models of asphyxia.@*METHODS@#Two asphyxia models were made and tissue samples of the dead rats were collected from different groups at various postmortem duration. The expression and the changes of HIF1-alpha in various tissues were examined by immunohistochemistry and image analysis techniques. Results Significant expression of HIF1-alpha was observed in the myocardial fibers, kidney cells, liver cells and lung cells in both asphyxia models, but not in the control group. The expression of HIF1-alpha in various tissues in the rat died of nitrogen gas breathing was found in the nuclei at 0 hour and the expression level decreased gradually thereafter. The HIF1-alpha expression level and duration in various tissues of the rat died of hanging were higher and longer than that of the former group, with a peak of the expression level observed 6 hours after death, and then started to decline in all tissues except the heart where the expression still showed an increase 24 hours after death. The control groups showed a steady expression in the cytoplasm but not in the nuclei.@*CONCLUSION@#HIF1-alpha appears to be a valuable biomarker in the diagnosis of asphyxia within 24 hours after death.

Comparison of the contents of ATP, ADP, and AMP in the cardiac muscle of rat killed by different manners / 法医学杂志

OBJECTIVE@#The content changes of energy substances in the cardiac muscle of rat killed by different manners were investigated to elucidate evidence that can be used to determine the modes of death and postmortem interval.@*METHODS@#One hundred and eighty rats were randomly allocated into 3 groups and killed by bleeding, suffocating, and neck breaking, respectively. The contents of ATP, ADP, and AMP in the cardiac muscle of rats killed by the different manners at different death intervals (0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 18, and 24 h) were measured by HPLC.@*RESULTS@#There were significant differences observed in the contents of ATP and AMP in the rats' cardiac muscle in different groups at most of the intervals (P < 0.05) and at all of the intervals within the same group (P < 0.01), but no differences were found in the ADP contents in any of the group at most of the intervals.@*CONCLUSION@#The content changes of energy substances (ATP and AMP) in the cardiac muscle of dead rats may provide a basis for determination of the death manners and postmortem intervals.