In view of the high content of fluorine in the water in Guangdong pro-vince,we detected the serum fluorine level in rabbits died of drowning andcompared with that obtained from rabbits immersed in water after deathfrom hanging.The fluorine content in water is about 15 folds higher than normal whilein control cases the serum fluorine values are slightly lower than normal.The fluorine content in human serum is similar with that of rabbits.Itsuggests that detection of serum fluorine content might be a valuable methodfor the diagnosis of drowning in those areas where there are high waterfluorine content.

For the purpose of timing of wounds,the measurement of K~+/Na~+ ratio of 36specimens of wister rat's muscles taken from the local burn area by the atomicabsorption spcetrophometry was carried out.The results showed that K~+/Na~+ ratio in specimens of burn formed 15,30,60minutes before death and 20 minutes after death reduced 47～82%(mean 71%),56～89%(mean 77%),69～94%(mean 86%)and 4～38%(mean 27%)respectively ascompared with the control muscles.Reduction rate of K~+/Na~+ ratio in ante-mortem group was more obvious than the postmortem ones.With the prolongationof the antemortem interval,the reduction of K~+/Na~+ ratio becomes more marked.We believe that this method is a simple and reliable method in timing woundsand it is valuable in forensic medicine practice.

Objective This research aimed to study if the cerebral vascular injury can be caused by the positional asphyxia. Method The brain tissue sections were studied immunohistochemically (SABC method) by using the anti-human von Willebrand Factor (vWF) and anti-human albumin as the first antibody. Results No positive expression of vWF and albumin was found in the cerebral blood vessels of control group. The vivid positive expression of albumin and vWF were observed in the positional asphyxia group. Conclusion The results indicate that the positional asphyxia can result the expression of the vWF in the cerebral vessels and it seems one of the injury markers in the cerebral blood vessels and can be used to probe the mechanism of positional asphyxia.

Objective To detect the loss of cardiac troponin T (CTnT) in human myocardial infarction. Methods Loss of cardiac troponin T in human myocardial infarction was detected by immunohistochemical LSAB method. Results Obvious depletion of CTnT was observed in cases died from myocardial infarction,and by the computer image analysis, the mean CTnT-depleting area in myocardial infarction group was significantly different from that in the control group(P

Objective To explore the relationship between the changes of lactate dehydrogenase (LDH) and cholinesterase (CHE) activities and death from hanging of bound upper limbs (DHBL). Methods After the animal model of DHBL was established, the LDH and CHE activities in the serum and tissues including diaphragm muscle and musculi gastrocnemius were determined. Results In DHBL group, LDH activity decreased significantly in diaphragm muscle as compared with that in musculi gastrocnemius (P0.05). In comparison with the control group, LDH activity lowered greatly in the diaphragm muscle(P0.05). Significant decrease in serum LDH in the DHBL group as compared with control group (P0.05). Conclusion Decrease in the LDH activity may be associated with hanging posture of bound upper limbs.

Experimental acute myocardial ischemia model of dog was established, and the postmortem stability of fibronectin for the diagnosis of mycardial infarction was studied with immunohistochemistry and image analysis technique. The results showed that the positive reaction areas of fibronectin in ischemic myocardial tissues decreased along with the prolongation of postmortem interval, but positive reaction of fibronectin could still be found in ischemic myocardia kept for 4 weeks postmortem. No positive reaction for fibronectin could be found in normal myocardia when kept for different times. So fibronectin is a quite stable marker for the postmortem diagnosis of myocardial infarction, and is of practical value in the forensic practice.

Demonstration of the abnormal distribution of Mb and Fn in electric injuries of skeletal muscles. The electrocution model of rats was established, and the human autopsy samples of electrocution were collected. Immunohistochemical study of myoglobin(Mb) and fibronectin(Fn) were performed on the skeletal muscles in the electric current pathways. The results showed that the muscle fibers showed the bamboo-like appearance and depletion of the Mb as well as the positive reaction of Fn which was called the python-pattern. This experiment proved that the bamboo-like appearance and python-pattern change of the skeletal muscle fibers have the practical value in the medicolegal diagnosis of electrocution without typical current mark.

For the purpose of establishment of a diagnostic method of mild viral myocarditis,an experimental mild viral myocarditis model was induced in Balb/c murine by coxsackie virus B 3.The cardiac tissue secfion were stained by LSAB-immunohistochemical method with anti fibronectin(Fn) antibody. The results demonstrated that the Fn deposition was found in the myocardium of mice with myocarditis and the mild degeneration of cardiomyocytes could be identified by Fn LSAB immunohistochemical staining.It is suggested that the Fn deposition in the myocardium tissue is one of the reliable marks of myocardium inflammation.

Experimental acute myocardial ischemia model of rat was established, and the changes of C5 complement in the ischemic myocardia were studied with immunohistochemistry and image analysis technique. The results showed that the positive reaction of C5 could be observed in ischemic myocardia at 15 min after ischemia, and the positive reaction area increased along with the prolongation of the ischemic period. It is concluded that the positive reaction of C5 in cardiomyocytes is a quite sensitive marker of early myocardial ischaemia.The immunohistochemical detection of C5 in cardiomyocytes will be a meaningful tool for the postmortem diagnosis of early myocardial ischaemia.

In order to explore the value of fibronectin (Fn) in the postmortem diagnosis of myocardial infarction.The changes of Fn staining in normal, infarcted and other non infarcted myocardial injuries resulted from myocarditis, mechanical asphyxia, electrocution, hemorrhagic shock, cardiac contusion and organophosphate poisoning were studied with immunohistochemistry and image analysis system. The results showed that positive Fn staining could only be observed in groups of myocardial infarction and myocarditis, but could not be found in groups of mechanical asphyxia, electrocution, hemorrhagic shock, cardiac contusion, organophosphate poisoning. It is indicated that positive reaction of Fn could be affected only by myocarditis, so it is quite specific for the diagnosis of myocardial infarction.