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The finite element method (FEM) is a mathematical method for obtaining approximate solutions to a wide variety of engineering problems. With the development of computer technology, it is gradually applied to the study of biomechanics of human body. The application of the combination of FEM and biomechanics in exploring the relationship between vascular injury and disease, and pathological mechanisms will be a technological innovation for traditional forensic medicine. This paper reviews the construction and development of human vascular FEM modeling, and its research progress on the vascular biomechanics. This paper also looks to the application prospects of FEM modeling in forensic pathology.

Objectives: To study the quantitative and qualitative differences of visual evoked potential (VEP) in monocular visual impairment after different parts of visual pathway injury., Methods: A total of 91 subjects with monocular visual impairment caused by trauma were selected and divided into intraocular refractive media-injury group (eyeball injury group for short), optic nerve injury group, central nervous system injury and intracranial combined injury group according to the injury cause and anatomical segment. Pattern Reversal visual evoked potential (PR-VEP) P100 peak time and amplitude, Flash visual evoked potential (F-VEP) P2 peak time and amplitude were recorded respectively. SPSS 26.0 software was used to analyze the differences of quantitative (peak time and amplitude) and qualitative indexes (spatial frequency sweep-VEP acuity threshold, and abnormal waveform category and frequency) of the four groups., Results: Compared with healthy eyes, the PR-VEP P100 waveforms of the intraocular eyeball injury group and the F-VEP P2 waveforms of the optic nerve group showed significant differences in prolonged peak time and decreased amplitude in injured eyes ( P <0.05). The PR-VEP amplitudes of healthy eyes were lower than those of injured eyes at multiple spatial frequencies in central nervous system injury group and intracranial combined injury group ( P <0.05).The amplitude of PR-VEP in patients with visual impairment involving central injury was lower than that in patients with eye injury at multiple spatial frequencies. The frequency of VEP P waveforms reaching the threshold of the intraocular injury group and the optic nerve injury group were siginificantly different from the intracranial combined injury group, respectively( P <0.008 3), and the frequency of abnormal reduction of VEP amplitude of threshold were significantly different from the central nervous system injury group, respectively( P <0.008 3)., Conclusions: VEP can distinguish central injury from peripheral injury, eyeball injury from nerve injury in peripheral injury, but cannot distinguish simple intracranial injury from complex injury, which provides basic data and basis for further research on the location of visual impairment injury.

In forensic traumatic pathology practice, immunohistochemistry and special staining technique play an important role in wound age estimation and complications of traumatic complication identification. They even play an important role in the identification of special cases, such as snakebites and insulin killings. This article reviews the application and value of immunohistochemistry and special staining techniques in forensic traumatic pathology based on the cases of forensic practice reported in literature.

Objectives: To explore the composition characteristic of event related potential （ERP） in different visual acuity levels, and to provide theoretical basis for the objective assessment of visual acuity., Methods: Monocular stimulus was performed on 16 selected subjects. The subjects were required to look straight at the screen ahead and count the amount of stimuli from different directions. The pictures of optotype stimulus which corresponding to three different visual acuity levels were showed in the center of the screen. The ERP results were recorded separately., Results: （1） The P₁ amplitudes of match stimuli recorded under the supra-threshold visual acuity level were higher than that of match stimuli recorded under the threshold and sub-threshold visual acuity levels. There was no significant difference between the P₁ amplitudes of match stimuli recorded under the threshold and sub-threshold visual acuity levels. The tendency of conflict stimuli was similar to that of match stimuli under three visual acuity levels. （2） In the 340-500 ms post-stimulus range, P₃₀₀ component was found under supra-threshold and threshold visual acuity levels; no P₃₀₀ component was found in corresponding time window under sub-threshold visual acuity. The differences of P₃₀₀ amplitudes among three visual acuity levels were statistically significant. The amplitudes from high to low were the supra-threshold, threshold and sub-threshold visual acuity levels., Conclusions: ERP can be a potential new method for the objective assessment of visual acuity in forensic medicine., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Forensic Medicine)

Objectives: To observe the changes of cystathionine β-synthase （CBS） expression in the cerebral cortex after brain contusion at different times., Methods: An experimental model of traumatic brain injury （TBI） in mice was established by an improved weight-drop device. Then Western blotting and immunohistochemical examination were used to detect the CBS expression in cerebral cortex around injury at different time points （1 h, 6 h, 12 h, 1 d, 2 d, 3 d, 7 d）., Results: The results of Western blotting revealed that the expression level of CBS was down-regulated and reached its lowest level at the 3rd days after injury, and then restored to normal level after 7 days. The results of immunohistochemistry showed that CBS was present in the normal brain cortex. CBS expression gradually decreased at the 3rd days after injury, and then restored to normal level after 7 days., Conclusions: CBS has the potential to be a reference index for time estimation after brain contusion in forensic practice., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Forensic Medicine)

Objectives: To study the effect of different attentional conditions on the event-related potential （ERP） components generated by the visual information stimuli related to visual acuity, and provide a theoretical reference for clinical forensic visual objective evaluation., Methods: With visual acuity optotypes as normal form of visual information stimuli, 15 volunteers as study subjects were supposed to account the visual acuity optotypes under the attentional condition of visual stimuli. Furthermore, the subjects were required to listen to the storytelling carefully under the non-attentional condition of visual stimuli, and after the examination, they needed to answer the story-related questions. All the EEG results of two different attentional conditions from the subjects were recorded by 32 channel ERP system., Results: Under two attentional conditions, P₁ and P₃₀₀ components were evoked by the visual acuity optotypes on supra-threshold and threshold visual acuity levels, while only P₁ component were evoked by the visual acuity optotypes on sub-threshold levels. In the ERP waveforms evoked by the visual acuity optotypes on supra-threshold, P₁ and P₃₀₀ amplitudes under attentional condition were larger than that under non-attentional condition., Conclusions: Attentional conditions can influence the detection of visual acuity. P₃₀₀ component can be used to distinguish the visual acuity levels with supra-threshold and sub-threshold under non-attentional condition., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Forensic Medicine)

Mild cognitive impairment caused by craniocerebral trauma is the key points and difficulties in judicial authentication. This article has comparative analysis of each mode of event-related potential (classical Oddball, Eriksen flanker task and so on), which can provide a more objective method for such craniocerebral trauma cases in clinical forensic judicial authentication.

Objective: To observe the time-course expression of zonula occludens-1 (ZO-1) in cerebral cortex after traumatic brain injury (TBI)., Methods: The TBI model of mouse was established. The mice were divided in 1 h, 3 h, 6 h, 12 h, 24 h, 3 d, 7 d after TBI, sham and control groups. The permeability of the blood brain barrier was evaluated by measuring the extravasation of Evans blue (EB) dye. The expression of ZO-1 in cerebral cortex in the injured area was detected by Western blotting and immunohistochemistry., Results: The extravasation of EB dye of injured cortex gradually increased from 1 h, peaked at 1-3 d and approximately decreased to normal at 7 d after TBI. Western blotting revealed that the expression of ZO-1 gradually decreased after 1 h, was at the lowest at 1-3 d, and then significantly increased after 7 d but was still lower than that of normal and sham groups. The result of immunohistochemistry showed that ZO-1 had strong expression in vessel of normal cortex, gradually decreased after TBI, and almost disappeared at 3 d after TBI and gradually recovered to normal level later., Conclusion: The expression of ZO-1 in the injured cortex after TBI initially decreases and then increases. The negative correlation between ZO-1 expression and EB extravasation after TBI could be used as a new indicator for wound age estimation.

Objective: To observe the time-course expression of calcium-calmodulin dependent protein kinase II delta (CaMK II delta) in cerebral cortex after traumatic brain injury (TBI)., Methods: The TBI rat model was established. The expression of CaMK II delta in cerebral cortex around injured area was tested by Western blotting and immunohistochemical staining., Results: Western blotting revealed expression of CaMK II delta in normal rat brain cortex. It gradually increased after TBI, peaked after 3 days, and then returned to normal level. The result of immunohistochemical staining was consistent with that of Western blotting., Conclusion: The expression of CaMK II delta around injured area after TBI increased initially and then decreased. It could be used as a new indicator for wound age determination following TBI.

Diagnosis of nervous system injury is one of the most difficult issues in medical-legal practice. Nowadays, the activation of NF-kappaB has been studied by many researchers in order to find objective evidence and indicators to calculate the injury time and to diagnose the severity of brain injury for forensic practice. It was reviewed that the advances and problems of NF-kappaB and its correlation with nervous system injury and diseases, such as cerebral ischemia, traumatic brain injury, Alzheimer's disease and amyotrophic lateral sclerosis.

Objective: To study the expression of cathepsin-B and -D in different time point after traumatic brain injury., Methods: Traumatic brain injury (TBI) model was established on rats, cathepsin-B and cathepsin-D immunofluorescence staining and confocal microscope analysis were performed. Positive cells were counted by confocal microscope and image analysis techniques were used to determine the morphological changes in each group., Results: Immunofluorescence staining results showed that cathepsin-B was activated 1 hour after TBI while cathepsin-D was not activated until 12hour after TBI. Both of them got to their peak during 4 to 8days, and kept a high level of activating 32days after TBI. Cathepsin-B and -D positive cells did not merge with caspase-3 positive cells until 6 h after TBI., Conclusion: Cathepsin-B and -D could be the diagnostic markers of TBI and can estimating time course of lateral TBI. They blocked caspase-3 activation at the beginning period after TBI and started to promote cell death with caspase-3 6 h after TBI.

Objective: To investigate the expression of NF-kappaB in different post-traumatic intervals and severity of brain injury., Methods: Fifty-four brain tissue samples of slight (n=24), moderate (n=24) brain injury, sham (n=3) and control (n=3) of rat were examined by immunohistochemical staining, westernblot and RT-PCR., Results: Up-regulating of NF-kappaB expression was found in tissues from traumatic brain injury compared with controls in early 1 hour after TBI, and reached peak at 24h and 48h and disappeared after 7 days. The expression of NF-kappaB mRNA has association with contusion severity., Conclusion: NF-kappaB may benefit to the estimation of posttraumatic intervals of brain injury.

Objective: To investigate the expression of caspase-3 in different posttraumatic intervals and severity of brain injury., Methods: The study examined brain tissue samples of slight (n = 24), severe (n = 24) brain injury and control (n = 6) of rat, using immunohistochemical staining, western-blot and RT-PCR method., Results: Up-regulating of caspase-3 expression was found in tissue from traumatic brain injury compared with controls in early 1 hour after TBI, and lasted for 14 days. The gray degree and threshold area of caspase-3 positive cells is different in different severity of brain injury., Conclusion: The increasing of caspase-3 expression indicates that TBI exists. The gray degree, threshold area of caspase-3 positive cells and the cleavage degree of pro-caspase-3 have association with the severity of brain injury.

Objective: In human, both in vivo and in vitro, telomere shortening appears to be a major component of cell senescence and aging. The detailed telomere shortening status and mechanism in peripheral blood cell is needed to be further characterized., Methods: One hundred and twenty three peripheral blood samples were collected from healthy individuals of different age groups and the mean telomeric restricted fragment (TRF) was measured using Southern Blotting with Dig labeled probe. The samples of different groups were homogenized in sex components as indicated by chi 2 test of sex ratio of different test groups (P > 0.05)., Results: The average length of TRF is shortening with aging and distinguished shortening dynamic profiles could be observed. Further analysis showed that there might be a shortening peak near the age of 5., Conclusion: There are distinguished dynamics profiles of telomere shortening among different age groups. Thus, the results indicate that it might be possible to infer individual age by telomeric restricted fragment length assay.

Many pathologic and physiologic changes occur after brain injury. Many genes control these changes. Caspase plays an important role in neuron cell apoptosis and has concern with secondary brain injury. It is of great significance in the forensic science.

Objective: To investigate the expression of caspase-1 in different posttraumatic intervals and severity of brain injury., Methods: The study examined brain tissue samples of slight (n = 24), severe (n = 24) brain injury and control (n = 6) of rat, using immunohistochemical staining, western-blot and RT-PCR method., Results: Up-regulating of caspase-1 expression was found in tissue from traumatic brain injury compared with controls in early 1 hour after TBI, and lasted for 2 weeks. Caspase-1 cleaved after brain injury., Conclusion: These findings are the first time to demonstrate the study of different intense brain injury. The increasing of caspase-1 expression indicates that the TBI exists. The threshold area of caspase-1 positive cells is different in different severity of brain injury.

Nuclear factor-kappa B (NF-kappa B) plays an important role in controlling infection, immunity responses, cellar differentiation and apoptosis. It is of characteristics especially in neural system. NF-kappa B exist widely in neural cells and transfer from plasma into nucleolus through diversified activation passages. in addition, NF-kappa B is also a key factor in the development of the neural system, anti-apoptosis and modulating the activity of glia cells. It is of great significance in the forensic science.

After the model of experimental brain contusion was set up, the changes of GFAP, PCNA were studied by immunohistochemistry SP method combined with image quantity analysis. After contusion, the gray degrees and areas of GFAP-positive cells increased significantly at the 3rd hour, reached the highest level in the 4th day and kept until the 7th day. PCNA-positive cells appeared in the 12th hour, simultaneously, their gray degrees tended to increase and positive areas tended to decrease. It showed regular changes of GFAP, PCNA with various survival times, and these changes were useful in the diagnosis of brain contusion especially in the period from the second to 7th day after injury. The numbers of astrocytes increased and reached the highest level in the 3rd day after contusion while the reactive proliferation of astrocytes is only a minor phenomenon.