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Estimation of postmortem interval using kinetic analysis of the third component of complement (C3) cleavage
Y Kominato1, K Kumada, K Yamazaki
1Department of Legal Medicine, University of Tsukuba, Ibaraki-ken, Japan.
Insights
Estimating the postmortem interval (PMI) can be achieved by measuring the cleavage of the third component of complement (C3) in blood. This study shows C3 cleavage correlates with time since death, aiding PMI estimation.
Area of Science:
- Forensic Science
- Biochemistry
- Immunology
Background:
- Accurate estimation of the postmortem interval (PMI) is crucial in forensic investigations.
- Current methods for PMI determination have limitations.
- The third component of complement (C3) undergoes spontaneous cleavage, potentially correlating with time since death.
Purpose of the Study:
- To investigate the potential of C3 cleavage as a biomarker for estimating PMI.
- To develop a method for PMI estimation based on C3 cleavage kinetics.
Main Methods:
- Studied spontaneous C3 cleavage in aged and cadaveric blood using crossed immunoelectrophoresis.
- Applied kinetic models (first-order reaction, Arrhenius' equation) and body cooling equations to calculate C3 cleavage percentages.
- Correlated calculated C3 cleavage percentages with measured percentages in cadaveric blood.
Main Results:
- A significant positive correlation was observed between calculated and measured C3 cleavage percentages (up to 10%) in cadaveric blood.
- The developed method demonstrated the potential for estimating PMI based on C3 cleavage levels.
Conclusions:
- C3 cleavage in blood shows promise as a reliable indicator for PMI estimation.
- This biochemical approach offers a new avenue for developing accurate PMI determination methods.
Abstract:
To estimate postmortem interval (PMI), spontaneous cleavage of the third component of complement (C3) was studied in aged blood and cadaveric blood by crossed immunoelectrophoresis. Using the kinetics of C3 cleavage in vitro described as dC/dt = -kC, where C is the concentration of native C3 at time t and k is a first-order rate constant, Arrhenius' equation, and another equation which assumes a linear drop of body temperature after death, the percentages of C3 cleavage were calculated. There was a significant positive correlation between the calculated percentages and the measured percentages of up to 10% in cadaveric blood. We found that the comparison between the calculated percentage of C3 cleavage for each optional postmortem interval and the measured percentage of up to 10% in cadaveric blood leads to the estimation of PMI. This approach is one step towards the development of an accurate method for determining PMI based on C3 cleavage, that is, on a first-order reaction.