[The forensic implications of the relationship between the proteolytic enzymes activity and the changes in NADH and FAD fluorescence intensity in skeletal muscle when determining the time of death (experimental study)]. / Sudebno-meditsinskoe znachenie vzaimosvyazi aktivnosti proteoliticheskikh fermentov i dinamiki intensivnosti fluorestsentsii kofermentov NADH i FAD v skeletnoi myshtse pri diagnostike davnosti nastupleniya smerti (eksperimental'noe issledovanie).

OBJECTIVE: Evaluation of the relationship between the activity of proteolytic enzymes (cathepsin D and calpains) and the dynamics of the fluorescence intensity of the coenzymes nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) in the rats' skeletal muscles in relation to the time of death. The proteolytic activity of enzymes in rat skeletal muscle was determined at the postmortem time points corresponding to the most significant changes in the dynamics of coenzymes NADH and FAD fluorescence intensity. The proteolytic enzymes activity was found to be low during the period of increasing intensity of NADH fluorescence observed within 3 hours after death. An increase in the activity of proteolytic enzymes was registered in 4.5 hours after death which corresponds to the initial point of decrease in NADH fluorescence intensity. In 24 hours post-mortem, corresponding to increased FAD fluorescence intensity a significant decrease in the activity of calpains was found. The results of the study suggest that the nature of the postmortem dynamics of the fluorescence intensity of coenzymes is largely due to the peculiarities of intracellular proteolysis. The study results suggest that the pattern of post mortem changes in coenzyme fluorescence intensity is largely attributable to the specifics of intracellular proteolysis. The relationship between coenzyme fluorescence and molecular mechanisms of cell death confirms the viability and feasibility of laser-induced spectroscopy for post-mortem changes assessment when determining the time of death.

[Determination of the fluorescence intensity of coenzymes NADH and FAD in the skeletal muscle of the rat depending on the post-mortem interval]. / Opredelenie intensivnosti fluorestsentsii kofermentov NADN i FAD v skeletnoi myshtse krysy v zavisimosti ot davnosti nastupleniia smerti.

Aim of the study is to identify patterns of variations of the fluorescence intensity of NADH (reduced nicotinamide adenine dinucleotide) and FAD (oxidized flavin adenine dinucleotide) in the skeletal muscle depending on the time since death. For the evaluation of fluorescence intensity of the studied coenzymes, laser-induced spectroscopy in situ was used. We revealed the dynamic of the fluorescence intensity of NADH and FAD in the skeletal muscle of a rat at different times during the post-mortem period, and theoretically justified the observed phenomena. The results obtained allow us to consider the studied indicators as a potential criterion for determining the post-mortem interval.