ABSTRACT
Objective To investigate the curative effects of various infusion volumes on liver-related metabolic mechanism in the treatment of hemorrhagic shock.Methods A severe hemorrhagic shock rabbit model was established in 30 rabbits.The rabbits were randomly divided into three groups:non-infusion group (A), conventional infusion group (B), and excessive infusion group (C) (n=10 in each group).Taking group B as the control, groups A and C were observed for the damage of non-infusion and excessive infusion, respectively.The outcomes in the three groups and their relations with liver tissue metabolism changes were analyzed with gas chromatograph-mass spectrometer (GC-MS).Results The mortality in groups A, B, and C group were 80％, 0％, and 70％, respectively.The liver tissue metabolic profile in group B showed statistically significant difference compared with that in groups A and B.In group C, the levels of 21 metabolites were lower than those in group B, and the levels of8 metabolites were lower than those in group A.The relative contents of various metabolites were correlated with infusion volumes, and the succinic acid content was associated with death events (P＜0.05).Conclusion The conventional infusion has significant curative effect on hemorrhagic shock.The metabolites of liver tissues with excessive infusion are generally decompensated and have longer survival time than those in non-infusion group, which may caused by the excessive infusion-induced blood volume increase after hemorrhagic shock.Tissue fluid dilution is an important cause of death.
ABSTRACT
Objective To explore the regularity of time-dependent changes in morphology and biomechanical properties of brain tissues in pigs, and value the feasibility of deducing the postmortem interval (PMI). Methods Brain tissues were taken from 42 pigs and kept in an artificial climate chamber with the temperature of 25 ℃ and humidity of 75%. The samples were collected from telencephalon at sequential time intervals (0, 12, 24, 36, 48, 60 h；n=6) according to the principle of predefined time, position, direction, ratio, quantity and shape. The samples fixed with formaldehyde were then immediately tested by mechanical testing machine to obtain their biomechanical parameters and the histological sections were prepared. Results With the extension of PMI (0-60 h), brain tissues gradually became discolored, weak, mudding and liquefied under the influence of autolysis and putrefaction. Both clearance area of the white matter and its integrated optical density (IOD) significantly increased during 0-48 h. Biomechanical properties of brain tissues including the limit load, average force, elastic modulus and fracture energy all presented a declining tendency at the interval of 12-60 h. The limit load was considered highly statistically significant, and statistical differences were found in average force, elastic modulus and fracture energy. Conclusions There exists a significantly negative structure-activity relationship between the morphology of brain tissues and biomechanical properties. The limit load of postmortem brain tissues in 60 h is the optimum in the window period, which can be used as a new method for estimating PMI.
ABSTRACT
Objective To explore the regularity of time-dependent changes in morphology and biomechanical properties of brain tissues in pigs,and value the feasibility of deducing the postmortem interval (PMI).Methods Brain tissues were taken from 42 pigs and kept in an artificial climate chamber with the temperature of 25 ℃ and humidity of 75％.The samples were collected from telencephalon at sequential time intervals (0,12,24,36,48,60 h;n =6) according to the principle of predefined time,position,direction,ratio,quantity and shape.The samples fixed with formaldehyde were then immediately tested by mechanical testing machine to obtain their biomechanical parameters and the histological sections were prepared.Results With the extension of PMI (0-60 h),brain tissues gradually became discolored,weak,mudding and liquefied under the influence of autolysis and putrefaction.Both clearance area of the white matter and its integrated optical density (IOD) significantly increased during 0-48 h.Biomechanical properties of brain tissues including the limit load,average force,elastic modulus and fracture energy all presented a declining tendency at the interval of 12-60 h.The limit load was considered highly statistically significant,and statistical differences were found in average force,elastic modulus and fracture energy.Conclusions There exists a significantly negative structure-activity relationship between the morphology of brain tissues and biomechanical properties.The limit load of postmortem brain tissues in 60 h is the optimum in the window period,which can be used as a new method for estimating PMI.