[Correlation between postmortem intervals and the changes of electrical conductivity in vitreous humor in rabbits after death].

OBJECTIVE: To investigate the correlation between postmortem interval (PMI) and the changes of electrical conductivity in vitreous humor in rabbits after death. METHODS: The changes of electrical conductivity in vitreous humor in rabbits were measured using the conductivity meter under 30 degrees C during 0-48 hours and 20 degrees C during 0-120 hours after death. RESULTS: Electrical conductivity in vitreous humor in rabbits increased gradually under 30 degrees C and 20 degrees C from 0 to 48 hours and from 0-120 hours after death. The formulae of the relationship between PMI and conductivity under 30 degrees C and 20 degrees C were obtained by statistical analysis and the correlation coefficients were 0.970 and 0.983 (both P < 0.01), respectively. CONCLUSION: The increase of electrical conductivity in vitreous humor in rabbits after death may be used as the relatively objective parameter for PMI estimation.

[The expressions of HSP 70 mRNA and c-fos mRNA in the skeletal muscle and cardiac muscle of rabbits by electrocuted].

OBJECTIVE: To study the changes of HSP 70 mRNA and c-fos mRNA expression and to find a method to differentiate antemortem from postmortem electrocution. METHODS: Fifteen New Zealand rabbits were randomly divided into three groups, the antemortem electrocution group, the postmortem electrocution group, and the control group. Each group consists of five rabbits. The levels of HSP 70 mRNA and c-fos mRNA in skeletal muscle and cardiac muscle were examined with quantitative fluorescent RT-PCR. RESULTS: The levels of HSP 70 mRNA and c-fos mRNA in the antemortem electrocution group increased significantly (P<0.05), compared with that of the postmortem electrocution group. CONCLUSION: The changes of HSP 70 mRNA and c-fos mRNA expression in skeletal muscle and cardiac muscle can be used as an indicator to distinguish antemortem from postmortem electrocution.

[A forensic pathological study of eighty-two cases of adrenal hemorrhage].

OBJECTIVE: To analyze the relationship between adrenal hemorrhage and the cause of death, age and gender. METHODS: Eighty-two cases of adrenal hemorrhage were statistically analyzed. RESULTS: Adrenal hemorrhage occurred mostly in cases of sudden death, infection, trauma and asphyxia. Male had more chance than female to have adrenal hemorrhage. Adrenal hemorrhage caused by sudden death, trauma and poisoning was more frequently seen in young adults, whereas adrenal hemorrhage in children as well as in fetus and newborns was often caused by infection as well as sudden death and asphyxia respectively. Adrenal hemorrhage caused by sudden death and asphyxia was mainly located in medulla, while the infection usually induced hemorrhage in cortex. Adrenal hemorrhage caused by trauma showed an equal opportunity in either the cortex or medulla. CONCLUSION: Our data indicate that adrenal hemorrhage might provide some clues in searching for the cause of death.

[Scanning electron microscopic observation of erythrocytes and endothelial cells of electrified death rabbits].

OBJECTIVE: To identify electrified death of animals without electric marks. METHODS: Two animal models (model A and model B) of electrified death without electric marks were established. Model A: right anterior limb and left hind limb of rabbits were soddened by 0.1 mol/L PBS, and two pieces of wet gause which were soaked in the 0.1 mol/L PBS were winded on the right anterior limb and left hind limb of them, respectively, and then two nake wires were winded outside of the gause; then, the two wires were connected to the alternating current of 220 voltage (A1 group) or 110 voltage (AZ group) electrified. Model B: two nake wires were fixed at the bilaterals of an oblong container, then a small quantities water were infunded into it, about 1.5 cm deep, and then, one rabbit was put in each time; finally, the two wires were connected to the alternating current of 220 voltage (B1 group) or 110 voltage (B2 group) electrified. The erythrocytes and endothelium of aorta and pulmonary artery of the animals were observed under scanning electron microscopes. RESULTS: Pores were found on the surface of the erythrocytes and endothelial cells of aorta and pulmonary artery of the electrified animals, which was absent in the control animals. The erythrocytes had the greatest perforated cell index among the three cells, followed by the pulmonary endothelium. CONCLUSION: The perforation phenomena can serve as an evidence of electrified death when no electric mark is observable.

[Expressions of GABA and GABA(A)R-alpha1 in the brain of rats poisoned by tetramine].

OBJECTIVE: Expressions of GABA and GABA(A)R-alpha1 in the brain of rats poisoned by Tetramine were analyzed to explore the intoxication mechanism. Methods Sixty rats were randomly divided into control, sham poisoned, high-dose poisoned (1.0 mg/kg tetramine) and low-dose poisoned (0.1 mg/kg) groups. The expressions of GABA and GABA(A)R-alpha1 in the brain of the poisoned rats were detected and analyzed by immunohistochemistry and imaging analyzer. Results The expressions of both GABA and GABA(A)R-alpha1 were diffusely seen in the brains of the control and shame poisoned rat groups with a moderate expression level, whereas the expressions of both GABA and GABA(A)R-alpha1 were decreased in the brains of the high-dose poisoned group. In the low-dose poisoned rat group, the expression of GABA initially decreased and reached its lowest level 6 hours after poisoning, and then started to show an increase and reached the level of control groups at day 3. The expressions level reached its peak at days 5-7 after poisoning and remained above the level of control groups till 10 days after poisoning. Similarly, the expression of GABA(A)R-alpha1 in the brains of the low-dose poisoned group initially decreased and reached its lowest level 6-12 hrs after poisoning, and then started to increase and reached the level of control groups at days 7-10 after poisoning, respectively. Conclusion The expression of both GABA and GABA(A)R-alpha1 decreased in the brains of the high-dose poisoned rat group and these changes of GABA and GABA(A)R-alpha1 expressions may be associated with underlying mechanism of tetramine poisoning.

[Postmortem changes of liver phosphofructokinase-2 level in rats following different causes of death].

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.

[Advance of study on pathological mechanism of paraquat poisoning].

Paraquat which is used widely as a potent herbicide is poisonous, and its pathological mechanism is unclear. Studies show that it is so a strong oxidant that it can oxidate lipid and some enzyme, also, it can damage DNA directly or induce necrosis or apoptosis, which is marked in pulmonary. To offer new directions for treatment and studies on paraquat poisoning, this paper reviewed the foreign studies on mechanism of it.

[A study on the expression of HSP70 in endothelial cells pretreated with ethanol and fluid shear stress].

OBJECTIVE: To detect whether ethanol can affect the expression of HSP70 in endothelial cells under fluid shear stress. METHODS: Ethanol at different concentrations was added to the culture medium of endothelial cells, EA. Hy926, which was treated statically or under 1Pa fluid shear stress. After the incubation of 1 h, 2 h, 4 h and 6 h, the expression of HSP70 was detected by immunohistochemical method(SP). RESULTS: In the control group, the expression of HSP70 was negative under static state, while it was positive under 1Pa fluid shear stress lasting 4 h even without ethanol. No statistic difference was found between the 50 mg/dL ethanol group and the control group with the same treatment time of fluid shear stress. HSP70 expression was found under static state with 150 mg/dL ethanol after 4 h or 300 mg/dL ethanol after 2 h respectively. The expression increased greatly under 1Pa fluid shear stress in the same ethanol concentrations. CONCLUSION: Medium to high ethanol concentration in coordination with fluid shear stress can strongly stimulates the expression of HSP70 by a kinetic mechanism of time-dependent.

[Contents of vitreous humor of dead body with different postmortem intervals].

OBJECTIVE: To establish regression correlations between postmortem interval (PMI) and contents of human vitreous humor of dead bodies for forensic purposes. METHODS: The human vitreous humor were taken from 126 dead bodies between 0.5 to 216 hours after death, and 11 chemical elements were detected by the OLYMPUS AU400 auto-biochemistry instrument. RESULTS: (1) The glucose, natrium and chlorine in human vitreous humor decreased, while the urea, creatinine, uric acid, potassium, calcium, magnesium, phosphorus, and micro-protein increased after death. The change of glucose, potassium and phosphorus were well correlated with the PMI (r = 0.824, 0.967, 0.880). But the uric acid and micro-protein did not have a good correlation with the PMI(r = 0.350, 0.153). (2) The stepwise regression analysis established the following equations for the PMI (Y): Y = -35. 15+6.05X, R2 = 0.957 (X = potassium); Y = -27.83+ 5.49X(1) - 1.35X(2), R2 = 0.960 (X(1) = potassium, X(2) = glucose); Y = -6.37+3.93X(1) -2.29X(2) + 5.36X(3), R2 = 0.966 (X(1) = potassium, X(2) = glucose, X(3) = phosphorus). CONCLUSIONS: (1) Eleven chemical components in human vitreous humor change after death, among which postassium has the best linear correlation with the PMI within 72 hours after death. (2) The accuracy of the estimation of PMI could be improved by establishing a multi-variable equation through stepwise regression.

[A study on expression of caspase-8 in organs of rats after electrical injury at antemortem or postmortem].

OBJECTIVE: This study was conducted to detect the expression of caspase-8 in organs of rats after The electrical injury so as to elucidate whether caspase-8 is useful in identifying electrical lesion. METHODS: experiment included two parts. In the first part (the antemortem electrical injury part), thirty-five healthy male SD rats were randomly divided into seven groups (n = 5 per group), i. e. the group of rats subjected to instantaneous electrothanasia; the groups of rats subjected to cervical dislocation at 1 h, 2 h, 4 h, 8 h after electrical injury; the sham group and the normal control group. In the second part (the postmortem electrical injury part), twenty-five healthy male SD rats wererandomly divided into five groups (n=5 per group), i. e. the groups of rats electrically injured just after death, and at 15 min, 30 min, 60 min after death; and the postmortem sham group. All experimental rats were given respectively an electric shock with two metal clamps that were connected with two poles of 220 V alternating current by clamping the rats' left hind limbs and right forelimbs. The rats of sham group after death were clamped but not electrified. The brain, lung, heart, liver, spleen, kidney, the muscle of electrified limb, the cutis of electrified limb of all experimental rats and those organs of control groups were dissected to detect the expression of caspase-8 by immunohistochemistry staining, and the staining intensities were assessed by image analysis system. RESULTS: In the antemortem electrical injury groups, the expression of caspase-8 was positive in brain, heart, liver and kidney; the strongest staining intensity appeard at 4 h after electrical injury and decreased at 8 h after electrical injury. In the group of rats electrically injuryed just after death, the expression of caspase-8 was faint, and the expression of caspase-8 in spleen, lung, muscle and cutis was negative in the other groups. The expression of caspase-8 in all detected organs was negative in the other rats that were electrified after death. CONCLUSION: Caspase-8 can be regarded as an index in identifying electrical injury and distinguishing between antemortem and postmortem electrical injuryies.

[Expression of Cyt C in brain of rats poisoned by tetramine].

OBJECTIVE: To investigate the evidence for the judgement on legal cases of intoxication by tetramine. METHODS: Fifty rats given tetramine by lavage were sacrificed at different time after intoxication. The expression of Cyt C was detected by immunohistochemistry, and the reasults were assessed by an image analysis system. RESULTS: There was a slight expression of Cyt C in control group. In intoxication group the expression of Cyt C increased after the rats were given tetramine for 30 minutes; it reached the peak at 24 hours after intoxication and kept up the level for 3 days, then it began to decrease and returned to the control level in 10 days. CONCLUSION: The regular change of Cyt C expression might be a useful sign for assessment in legal cases of intoxication by tetramine.

[Change of brainstem auditory evoked potential with different stimulating frequencies after closed diffuse brain injuries of rat].

UNLABELLED: OBJECTIVE To investigate the change of peak latency (PL), interpeak latency (IPL) and peak latency ratio (PL ratio) of brainstem auditory evoked potential (BAEP) with different stimulating frequencies after closed diffuse brain injuries of rat,and provide experimental evidence for clinical diagnosis of traumatic brain injury in early stage and also for Forensic practice. METHODS: A rat model for closed diffuse brain injury was successfully constructed by hit the parietal bone with a spring-driven steel stick. The auditory brainstem response (ABR) evoked by clicking with low stimulating frequency of 10 Hz and high stimulating frequency of 50 Hz were respectively recorded at 6 h, 12 h, 2 d, 4 d after brain injury. The results of experimented group were compared with those of control group. RESULTS: The 2 d, 4 d V PL and the 6 h, 12 h, 2 d, 4 d III-V IPL of BAEP with 50 Hz stimulating frequency of model group became longer than those of control group (P < 0.05), but there was no significant difference observed between model and control group experimented with low stimulating frequency of 10 Hz (P > 0.05). The PL ratio of III/I, IV/I, V/I, IV/III and V/III with different stimulating frequencies had no significant postinjury changes. Conclusion The high stimulating frequency of BAEP is a reliable test for diagnosis of TBI in early period. Its sensitivity is superior to the low simulating frequency.

[The relationship of injury timing with the change of neuronal apoptosis and the expression of caspase-3 after brain contusion].

OBJECTIVE: To investigate and analyze the changes of neuronal-apoptosis and the expression of caspase-3 for finding out a new method of injury timing after brain contusion in human. METHODS: The tissue was stained by TUNEL for apoptosis and by immunohistochemistry for caspase-3. Image analysis technique was employed. RESULTS: The nerve cells stained positive by TUNEL and Caspase-3 immunohistochemistry were distributed in the penumbra and central area. Both these areas were in striking contrast with the distal area or those of control group. The positive staining was more prominente in penumbra area than in central area (P < 0.05). The changes of TUNEL staining and expression of Caspase-3 in penumbra area gradually increased with the survival period after injury; they were parallel to each other. There were linear relationships between the time of injury in 48 hours and the increase in the mean of integral optical density (IOD), the coefficient of correlation (r) being 0.93 and 0.69 for the two staining methods, and two linear regression formulae were induced, respectively. CONCLUSION: Observations on the increasing of neuronal apoptosis and Caspase-3 expression in relation with the survival period after injury could be utilized in the timing of brain contusion.

[The advances in the neuropathology of sudden infant death syndrome].

Sudden infant death syndrome is known as sudden death in 12 months postnatal without obvious cause, the cause of death and differential diagnosis of still couldn't be indefinite so far. In this paper, the recent studies on the SIDS neuropathology using immunohisto-chemical technology were reviewed in order to suggest the lethal patho-physiologic derangement or mechanism in SIDS involves dysfunction of sleep-related cardio-respiratory homeostatic controls or failure to arouse. Thus the main cause of SIDS lies in central nerve system, but not unique cause.

[Dynamic observation of brainstem auditory evoked potential and pathological changes of the brain after closed brain injuries in rats].

OBJECTIVE: To investigate the dynamic experiences of pathological changes in brain and the injured role of brainstem auditory evoked potential (BAEP) after closed Mild Traumatic Brain Injury (MTBI) in rat. METHODS: A closed diffuse brain injury model was successfully produced in rat by hit the parietal bone with a spring-droved steel stick. The auditory brainstem response evoked by click at 50Hz stimulating frequency were recorded at pre-trauma, 15 min and 1, 3, 6, 12 h and 1, 2, 4, 7, 10, 14, 21 d after brain injury. The pathological changes of brain were observed under light microscope and the brain edema was detected by wet weight/dry weight rations. RESULTS: The I-V, III-V of BAEP wave inter peak latency (IPL) in MTBI group increased immediately in 15 minutes after injury. The III, V wave peak latency (PL) and I-V, III-V wave IPL became longer than the pre-trauma level in 6, 12 h post-injury (P<0.05). The III, V wave PL and I - III, I - V, III - V wave IPL became longer than the pre-trauma level in 1, 2 d after injury (P < 0.001), the BAEP retuned to normal level in 14 d after brain injury. At 15 minutes after injury, the water content in brain increased and met its peak in 1 d, decreased gradually in 4 d, then decreased slowly and returned to normal level in 10 d after injury. CONCLUSION: The regular changes of BAEP could be an objective tool for evaluating hearing dysfunction after closed mild diffuse traumatic brain injury.

[Expressions of Bcl-2 and Caspase-3 in the internal organs of rats when tetramine was administered].

OBJECTIVE: To find whether Bcl-2 and Caspase-3 take part in the pathophysiological mechanism of tetramine toxification. METHODS: Sixty Sprague-Dawley rats were divided into normal control group, the sham poisoned group, high dose poisoned group, low dose poisoned group. High dose poisoned group were administered 1.0 mg/kg weight body tetramine by mouth, however low dose poisoned group was administered tetramine 0.1 mg/kg weight body by mouth. The rats of the sham poisoned group were administered water, and rats of normal control group were given nothing. Bcl-2 and Caspase-3 were detected by immunohistochemistry staining and the results were assessed by image analysis system. RESULTS: The expressions of Bcl-2 and Caspase-3 in all organs were similar, ie, Bcl-2 and Caspase-3 expressed obviously in all organs of high dose poisoned group; in all organs of low dose poisoned group, they were hardly detected at 30 min after administration, however, at 3 h after administration, they could be detected obviously; Bcl-2 got to peak at 6 h-3 d after administration and Caspase-3 got to peak at 24 h-3 d after administration. CONCLUSION: Bcl-2 and Caspase-3 take part in the pathophysiological procedure of tetramine poisoned rats.

[To estimate early postmortem interval by investigating changes of rats' gastrocnemius excitability].

OBJECTIVE: To investigate the changes of excitability of rats' gastrocnemius after rats were died from mechanic asphyxia, so as to make an objective evidence for estimating of the early postmortem interval. METHODS: After rats were sacrificed by mechanic asphyxia, the reaction of rats' gastrocnemius to variable electric stimulation at different period after death were recorded by electricphysiological method. RESULTS: Changes in the properties of excitable tissue to electric stimulate in rats' gastrocnemius after mechanic asphyxia seems to be well correlated with the early postmortem interval and appeared a linear relation in certain period. CONCLUSION: The regular changes of excitability in muscle might be a useful means for estimating of early postmortem interval.

[Relationship between the injury time and DNA fragmentation and its quantity in rat brain].

OBJECTIVE: To observe the changes of DNA fragmentation and its quantity along with the time of injury in nerve cells after brain contusion. METHODS: The model of brain contusion caused by free drop hammer was established. TUNEL and Feulgen's DNA staining conjoined with image analysis technique were used for exploration. RESULTS: With the gradually rising of DNA fragmentation, DNA quantity was declining in the brain tissue after contusion. CONCLUSION: TUNEL and Feulgen's DNA staining conjoined with image analysis technique could be utilized in the timing of brain injury and provide a new approach for this issue.

[Observation the electroporation of blood cells in vitro by scanning electron microscope].

OBJECTIVE: To observe changes on cell membrane in blood cells after they were been electrified. METHODS: Blood were electrified for 5, 10, 20, 30 s, 1 min respectively, and Scanning electron microscope was used to detect the changes on their cell membranes. RESULTS: Pores were detected both on electrified erythrocytes and leukocytes with round or ellipse shapes. The erythrocytes often have one or more pores while the leukocytes often have more pores looked like cribble. The rates of perforated cells were increased with the prolonging time of electrification, 5 s with 6% and 1 min increased to 40%. CONCLUSIONS: Alternating current can cause the cell perforating, and the rates of perforated cell were increased with the prolonging time of electrification.

[Expression of c-fos protein after muscle contusion in experimental rats].

OBJECTIVE: To study the relationship between the expression of c-Fos protooncogene and skeleton muscle contusion of rats, and to search for a sensitive marker of timing for skeleton muscle contusion. METHODS: Fifty Sprague-Dawley rats were randomly distributed into control group and experimental groups. The expression of c-fos was microscopically observed by immunohistochemical method. RESULTS: With the time prolonged the c-fos positive intensity and area were increased. Positive expression of c-fos protein appeared at 15 min after skeleton muscle contusion, and reached to the peak at 1h after skeleton muscle contusion, then decreased gradually and returned to the normal level on 1d after skeleton muscle contusion. CONCLUSION: The detection of the expression of c-fos protein could be a sensitive marker for timing skeleton muscle contusion.