8-oxoguanine DNA glycosylase-1 may serve as biomarker of mechanical asphyxia.

AIM: To identify mtDNA and OGG1 as potential biomarker candidates for mechanical asphyxia. METHOD: The human tissues are divided into experimental group (hanging and strangulation) and control groups (hemorrhagic shock, brain injury group, and poisoning group). Detected the expression of OGG1 and integrity of mtDNA in cardiac tissue of each group. We used over-OGG1 vector and siRNA-OGG1 transfecting H9C2 cell line to observe the function of OGG1 in hypoxic cells. RESULTS: 1. mtDNA integrity decreased in the mechanical asphyxia group, OGG1 expression increased in mechanical asphyxia groups. They can be biomarkers for mechanical asphyxia. 2. OGG1 increased first and decreased in hypoxia-induced H9C2 cells. OGG1 upregulated the TFAM, NRF1, and Bcl2 in hypoxia-induced H9C2. OGG1 downregulated cleaved-Caspase3 in hypoxia-induced H9C2 cells. 3. In the normoxia condition, NAC maintained mtDNA integrity and decreased the mitochondrial membrane potential and amount of ATP. CONCLUSION: mtDNA integrity and OGG1 expression can be biomarkers for mechanical asphyxia. OGG1 can maintain mtDNA integrity and maintain the stability of the mitochondrial membrane.

Determining Whether an Individual is 18 Years or Older Based on the Third Molar Root Pulp Visibility in East China.

OBJECTIVES: To investigate the age-related changes of the mandibular third molar root pulp visibility in individuals in East China, and to explore the feasibility of applying this method to determine whether an individual is 18 years or older. METHODS: A total of 1 280 oral panoramic images were collected from the 15-30 years old East China population, and the mandibular third molar root pulp visibility in all oral panoramic images was evaluated using OLZE 0-3 four-stage method, and the age distribution of the samples at each stage was analyzed using descriptive statistics. RESULTS: Stages 0, 1, 2 and 3 first appeared in 16.88, 19.18, 21.91 and 25.44 years for males and in 17.47, 20.91, 22.01 and 26.01 years for females. In all samples, individuals at stages 1 to 3 were over 18 years old. CONCLUSIONS: It is feasible to determine whether an individual in East China is 18 years or older based on the mandibular third molar root pulp visibility on oral panoramic images.

SREBP1 deficiency diminishes glutamate-mediated HT22 cell damage and hippocampal neuronal pyroptosis induced by status epilepticus.

Status epilepticus (SE) is a life-threatening disorder that can result in death or severe brain damage, and there is a substantial body of evidence suggesting a strong association between pyroptosis and SE. Sterol regulatory element binding protein 1 (SREBP1) is a significant transcription factor participating in both lipid homeostasis and glucose metabolism. However, the function of SREBP1 in pyroptosis during SE remains unknown. In this study, we established a SE rat model by intraperitoneal injection of lithium chloride and pilocarpine in vivo. Additionally, we treated HT22 hippocampal cells with glutamate to create neuronal injury models in vitro. Our results demonstrated a significant induction of SREBP1, inflammasomes, and pyroptosis in the hippocampus of SE rats and glutamate-treated HT22 cells. Moreover, we found that SREBP1 is regulated by the mTOR signaling pathway, and inhibiting mTOR signaling contributed to the amelioration of SE-induced hippocampal neuron pyroptosis, accompanied by a reduction in SREBP1 expression. Furthermore, we conducted siRNA-mediated knockdown of SREBP1 in HT22 cells and observed a significant reversal of glutamate-induced cell death, activation of inflammasomes, and pyroptosis. Importantly, our confocal immunofluorescence analysis revealed the co-localization of SREBP1 and NLRP1. In conclusion, our findings suggest that deficiency of SREBP1 attenuates glutamate-induced HT22 cell injury and hippocampal neuronal pyroptosis in rats following SE. Targeting SREBP1 may hold promise as a therapeutic strategy for SE.

Sex Estimation of Medial Aspect of the Ischiopubic Ramus in Adults Based on Deep Learning.

OBJECTIVES: To investigate the reliability and accuracy of deep learning technology in automatic sex estimation using the 3D reconstructed images of the computed tomography (CT) from the Chinese Han population. METHODS: The pelvic CT images of 700 individuals (350 males and 350 females) of the Chinese Han population aged 20 to 85 years were collected and reconstructed into 3D virtual skeletal models. The feature region images of the medial aspect of the ischiopubic ramus (MIPR) were intercepted. The Inception v4 was adopted as the image recognition model, and two methods of initial learning and transfer learning were used for training. Eighty percent of the individuals' images were randomly selected as the training and validation dataset, and the remaining were used as the test dataset. The left and right sides of the MIPR images were trained separately and combinedly. Subsequently, the models' performance was evaluated by overall accuracy, female accuracy, male accuracy, etc. RESULTS: When both sides of the MIPR images were trained separately with initial learning, the overall accuracy of the right model was 95.7%, the female accuracy and male accuracy were both 95.7%; the overall accuracy of the left model was 92.1%, the female accuracy was 88.6% and the male accuracy was 95.7%. When the left and right MIPR images were combined to train with initial learning, the overall accuracy of the model was 94.6%, the female accuracy was 92.1% and the male accuracy was 97.1%. When the left and right MIPR images were combined to train with transfer learning, the model achieved an overall accuracy of 95.7%, and the female and male accuracies were both 95.7%. CONCLUSIONS: The use of deep learning model of Inception v4 and transfer learning algorithm to construct a sex estimation model for pelvic MIPR images of Chinese Han population has high accuracy and well generalizability in human remains, which can effectively estimate the sex in adults.

Research Progress on Molecular Changes in Pulmonary Hypoxia and Cause of Death Identification in Mechanical Asphyxia.

Lung is the largest organ of the respiratory system. During hypoxia, pulmonary cells undergo rapid damage changes and activate the self-rescue pathways, thus leading to complex biomacromolecule modification. Death from mechanical asphyxia refers to death due to acute respiratory disorder caused by mechanical violence. Because of the absence of characteristic signs in corpse, the accurate identification of mechanical asphyxia has always been the difficulty in forensic pathology. This paper reviews the biomacromolecule changes under the pulmonary hypoxia condition and discusses the possibility of application of these changes to accurate identification of death from mechanical asphyxia, aiming to provide new ideas for related research.

Individual Identification in Facial Appearance Biometrics Based on Macroscopical Comparison.

Individual identification is one of the research hotspots in the practice of forensic science, and the judgment is usually built on the comparison of the unique biological characteristics of the individual, such as fingerprints, iris and DNA. With the dramatic increase in the number of cases related to video image investigations, there is an increasing need for the technology to identify individuals based on the macroscopic comparison of facial appearance biometrics. At present, with the introduction of computer three-dimensional (3D) modeling and 3D superimposition comparison technology, considerable progress has been made in individual identification methods based on macroscopic comparison of facial appearance biometrics. This paper reviews individual facial appearance biometric methods based on macroscopical comparison, comprehensively analyzes the advantages and limitations of different methods, and puts forward recommendations and prospects for subsequent research.

Forensic Examination of Six Homicide Injection Cases.

OBJECTIVES: To retrospectively analyze homicide cases of death after injection and provide reference for forensic identification. METHODS: Six homicide cases of death after injection which were investigated by the Criminal Investigation Team of Shanghai Public Security Bureau were collected and analyzed, including case situation, scene investigation, autopsy and other materials. RESULTS: The 6 cases were premeditated crimes, 5 cases took place in private spaces, and 5 cases involved the victims approached by suspects' decoy. There were no obvious abnormalities at the scene of the 6 cases. In 6 cases, the victim's body surface injury was mild or no, lividity color was abnormal, and the needlestick injury showed different manifestations from conventional medical measures. CONCLUSIONS: Death after injection is a highly concealed crime and easy to be ignored. For the suspected injection injury found in autopsy, it is necessary to carefully examine, identify and analyze, be alert to the situation of injecting poison (drug) and do a good job in evidence fixation and material extraction.

Research Progress of Automatic Diatom Test by Artificial Intelligence.

Diatom test is the main laboratory test method in the diagnosis of drowning in forensic medicine. It plays an important role in differentiating the antemortem drowning from the postmortem drowning and inferring drowning site. Artificial intelligence (AI) automatic diatom test is a technological innovation in forensic drowning diagnosis which is based on morphological characteristics of diatom, the application of AI algorithm to automatic identification and classification of diatom in tissues and organs. This paper discusses the morphological diatom test methods and reviews the research progress of automatic diatom recognition and classification involving AI algorithms. AI deep learning algorithm can assist diatom testing to obtain objective, accurate, and efficient qualitative and quantitative analysis results, which is expected to become a new direction of diatom testing research in the drowning of forensic medicine in the future.

Application of Diatoms Quantitative Analysis in the Diagnosis of Drowning.

OBJECTIVES: To retrospectively analyze diatom test cases of corpses in water and discuss the value of quantitative analysis of diatoms in the diagnosis of drowning. METHODS: A total of 490 cases of water-related death were collected. They were divided into drowning group and postmortem immersion group according to the cause of death. Diatoms in lung, liver, kidney tissue and water sample were analyzed quantitatively by microwave digestion-vacuum filtration-automated scanning electron microscopy (MD-VF-Auto SEM) method. The ratios of content of diatoms in lung tissue and water sample (CL/CD) were calculated. RESULTS: The results of diatom test for three organs (lung, liver and kidney) were all positive in 400 cases (85.5%); the content of diatom in lung, liver, kidney tissues, and water samples of drowning group were (113 235.9±317 868.1), (26.7±75.6), (23.3±52.2) and (12 113.3±21 760.0) cells/10 g, respectively; the species of diatom were (7.5±2.8), (2.6±1.9), (2.9±2.1) and (8.9±3.0) types, respectively; the CL/CD of drowning group and postmortem immersion group were (100.6±830.7) and (0.3±0.4), respectively. CONCLUSIONS: Quantitative analysis of diatoms can provide supportive evidence for the diagnosis of drowning, and the parameter CL/CD can be introduced into the analysis to make a more accurate diagnosis of drowning.

Estimation of the human postmortem interval using an established rat mathematical model and multi-RNA markers.

In our previous study, a R code-based mathematical model using RNA degradation patterns was developed for PMI determination in rat brain specimens. However, the postmortem changes of RNA are much more complicated in real cases, and there is still a huge challenge in efficiently applying information in animal data to real cases. In the present study, different RNA markers in both rat and human tissues were collected to screen valid biomarkers and the corresponding mathematical models were established and validated. With the same methodology, multi-RNA markers of myocardium and liver tissues were detected by qPCR and the Ct values of ten biomarkers generally increased with prolonged PMIs. 5S, miR-1 and miR-133a were shown to be optimum reference biomarkers that were not affected by a PMI of up to 5 or more days; however, liver-specific miR-122 began to degrade under higher temperatures and only 5S was selected as an endogenous control in the liver. Among the tested target RNAs, similar to our previous study in brain tissue, ß-actin (ΔCt) was found to exhibit the best correlation coefficient with PMI and was employed to build mathematical models using R software. Following validation, the relatively low estimated error demonstrated that PMIs can be accurately predicted in human cases through comprehensive consideration of various factors and using effective biomarkers.

RNA degradation as described by a mathematical model for postmortem interval determination.

Precisely determining the postmortem interval (PMI) is crucial to civil, criminal and forensic cases. A technique to exploit the postmortem RNA transcript level was developed to increase the accuracy and practicality of PMI estimation. For this purpose, lung tissues and muscle tissues were removed at twelve time points (0-144 h) from rat corpses that had been stored at three different temperatures (10, 20 and 30 °C). Human tissues were collected at autopsy from twelve real cases with known PMI values and other parameters. After the RNA was extracted from all these samples, the transcript levels of nine biomarkers were analyzed by real-time quantitative PCR (RT-qPCR). With the assistance of geNorm, miR-195, miR-200c, 5S, U6 and RPS29 were selected as reference biomarkers for lung specimens; miR-1, miR-206, 5S and RPS29 were chosen as control markers for muscle tissues. On the contrary, ACTB and GAPDH were significantly correlated with the PMI. The mathematical models using these target biomarkers were constructed to describe the characteristic relationship between △Ct values (normalized to reference biomarkers) and the observed PMI for each temperature group. Following validation, the relatively low error rates (7.4% and 12.5% for rat and human samples, respectively) demonstrated the accuracy and reliability of the mathematical model. We believe these results indicate that the multi-parametric mathematical model can become a practical tool for PMI estimation.

Unnatural deaths in Shanghai from 2000 to 2009: a retrospective study of forensic autopsy cases at the Shanghai Public Security Bureau.

Shanghai is the most developed city in China and has a soaring population. This study uses forensic epidemiology to determine the relationship between unnatural deaths and the development in Shanghai, based on recently released forensic autopsy cases from the 2000s at the Shanghai Public Security Bureau (SPSB). There were 5425 accidental deaths, 2696 homicides, 429 suicides, 186 natural deaths, and 1399 deaths of undetermined cause. There was a male-to-female ratio of 2.02:1, and the average age was 40.9±18.7 years. Traffic accidents (84.2%) were the number one cause of accidental deaths, which decreased during the study period. Sharp force injury (50.6%) was the leading cause of homicides, different from Western countries, where firearms are the leading cause. Hanging (24.5%) was the leading cause of suicides, whereas drug and chemical intoxication was the leading cause in the previous decade; pesticide ingestion decreased in the 2000s. In addition to traffic accidents, manual strangulation was the leading cause of death in childhood fatalities. Children under age 2 were vulnerable to homicides. In the 2000s, there were a large number of drug overdoses, and illegal medical practices and subway-related deaths first appeared in Shanghai. A new type of terrorist attack that involved injecting people with syringes in public places was reflected in the SPSB archives. The forensic epidemiology and changes in unnatural deaths in this decade reflected their relationship with the law, policy and changes in Shanghai. Illegal medical practices, subway-related deaths and terrorist attacks were closely related to the development in Shanghai. Identifying the risks of unnatural deaths will improve public health.

Suicidal drownings with psychiatric disorders in Shanghai: a retrospective study from 2010.1 to 2014.6.

Psychiatric disorders exhibited in 13% suicidal drownings in Southwestern Croatia and 63% in Milan, but in China is unknown. This study is committed to outline the feature of a suicidal drowning with psychiatric disorder, show mental status and reveal key factor to high incidence in China. Immersed corpses were handled by SPSBMPH in its jurisdiction range. Half of immersed corpses were suicidal, and nearly half of suicides had psychiatric disorders. 104 suicidal drownings with psychiatric disorders cases from 2010.1 to 2014.6 were reviewed (21.5% of all immersed corpses, 42.1% of suicides). Most victims clothed normally, and only 2 fastened attached weights. Male victims were more and younger than female. Psycho were prone to commit suicidal drowning in warm and hot season. Psycho were prone to choose familiar area to commit suicide, 45 decedents were found in their familiar areas. Suicidal drowings were occult without suicide attempts, suicide note or abnormal clothing, but showed abnormal mental or behavior changes prior to suicide. The three leading psychiatric disorders were depression (33.7%), depression status (30.8%) and schizophrenia (20.2%). Only 44.2% decedents had visited psychiatric disorder specialist, and merely less than 10% patients could adhere to regular medication. No regular medication on psychiatric disorder was the key factor contributing to high incidence of suicide in psycho. Professional psychiatric and psychological intervention should be taken as soon as possible when they had psychiatric symptoms or suffered misfortune. Guardians should be alert to patients' abnormality to detect their suicidal ideation and intervene, especially in warm season.

[Pathological Features of Myocardial Contraction Band Necrosis in Sudden Cardiac Death].

OBJECTIVE: To investigate the pathological features and significance of myocardial contraction band necrosis in sudden cardiac death. METHODS: Using HE and PTAH staining, the distribution sites and pathological features of myocardial contraction band necrosis were observed. The data were analyzed according to the extent of necrosis. RESULTS: The locations, pathological features and the extent of necrosis were similar in different sudden death cases. The locations were related with sites of myocardial damage. The papillary muscles of left ventricular were most occurred, followed by the anterior wall of left ventricular. In the sudden death cases caused by stress cardiomyopathy, the extent of myocardial contraction band necrosis was lighter than the others. Most cases were predominantly level 1, the others were level 2. CONCLUSION: Used as the diagnosis basis of acute myocardial ischemia, the myocardial contraction band necrosis has important significance to determination of death.

[Correlation between five RNA markers of rat's skin and PMI at different temperatures].

OBJECTIVE: To explore the correlation between postmortem interval (PMI) and five RNA markers of rat's skin--ß-actin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 18S ribosomal RNA(18S rRNA), 5S ribosomal RNA (5S rRNA), and microRNA-203 (miR-203), at different temperatures. METHODS: Eighteen SD rats were randomly divided into three environmental temperature groups: 4 °C, 15 °C and 35 °C, respectively. Skin samples were taken at 11 time points from 0 h to 120 h post-mortem. The total RNA was extracted from the skin samples and the five RNA levels were detected by real-time fluorescent quantitative PCR. Proper internal reference was selected by geNorm software. Regression analysis of the RNA markers was conducted by GraphPad software. RESULTS: 5S rRNA and miR-203 were most suitable internal references. A good linear relationship between PMI and RNA levels (ß-actin and GAPDH) was observed in two groups (4 °C and 15 °C), whereas the S type curve relationship between the expression levels of the two markers (ß-actin and GAPDH) and PMI was observed in the 35 °C group. The partial linear relationship between 18S rRNA and PMI was observed in the groups (15 °C and 35 °C). CONCLUSION: Skin could be a suitable material for extracting RNA. The RNA expression levels of ß-actin and GAPDH correlate well with PMI, and these RNA markers of skin tissue could be additional indice for the estimation of PMI.

[Analysis of false-positive hyoid fractures: 12 forensic identification cases].

OBJECTIVE: To study the causes of false-positive hyoid fractures and forensic identification. METHODS: Twelve cases of false-positive hyoid fractures were collected and analyzed. RESULTS: Improper dissection technique (4 cases) and congenital separation (8 cases) were the main reasons for false-positive hyoid fractures. CONCLUSION: True fractures can be differentiated from false-positive hyoid fractures. False-positive hyoid fracture caused by improper dissection technique can be identified through examination of peripheral muscle, soft tissue hemorrhage, and the characteristics of fracture end.

Epitome of China's unnatural deaths: a historically retrospective study of forensic autopsy cases in Shanghai Public Security Bureau from 1990 to 1999.

The unnatural death investigation in China seems vague to the world. Shanghai is one of the largest city located in Yangtze River Delta in the East China. This study is committed to lift the veil of unnatural death investigation and describe the epitome of China's unnatural deaths. Based on the 7302 forensic report archives from 1990 to 1999 in Shanghai Public Security Bureau, statistics were carried out in 5 areas according to the manner of death. In 3502 accidental deaths, there was a rapid increase during the 1990s, and 71.6% were involved in traffic accidents whose major cause of death was head and neck injuries. The first 3 causes of death in nontraffic accidents (994) were head and neck injuries (42.8%), poisoning (11.8%), and drowning (9.0%). In 2456 homicides, sharp force injury (36.7%), blunt force injury (35.8%), and manual strangulation (12.9%) were the first 3 causes of death. In 563 suicides, drug/chemical intoxication (40.1%), hanging (23.4%), and injuries because of fall from height (11.4%) were the 3 leading causes of death, especially pesticides ingestion. The causes of natural deaths were diseases mainly in circulatory system (23.1%), central nervous system (12.8%), and respiratory system (6.4%). However, the cause of death remained undetermined in 500 victims. Childhood fatalities were different. The victims of accidents and homicides were nearly equal, and the main cause of homicide was manual strangulation. Besides, 1997 was the landmark year when drug abuse began to emerge in Shanghai.

Postmortem interval determination using 18S-rRNA and microRNA.

The importance of determining postmortem interval (PMI) is crucial to criminal, civil and forensic cases. The precise estimation of PMI is a critical step in many death investigations. A technique exploiting the level of RNA, 18S rRNA and microRNA to estimate PMI was investigated. 18S-rRNA is a main ribosomal RNA presented as part of the ribosomal protein complex, while microRNA is a class of small non-coding single-stranded RNA, only 21-25 nucleotides, which has a strong conservation between different species. In this study, heart tissues were removed from adult rats at various postmortem intervals. An efficient extraction and detection protocol to analyze the level of 18S-rRNA and microRNA in postmortem tissue was carried out. The process consists of total RNA extraction, transcription and visualization by quantitative real time PCR. The result indicates a characteristic parabola relationship between postmortem period and Ct values for 18S-rRNA in dead rat hearts. The result indicates that the degradation pattern of tissue 18S-rRNA and microRNA is useful in the determination of the postmortem interval within seven days.

[Relationship between PMI and relative expression of myocardial various RNAs in rats died of different causes].

OBJECTIVE: To observe the changes of relative expression of myocardial various RNAs in rats died of different causes and their relationship with PMI. METHODS: The rat models were established in which the rats were sacrificed by broken neck, asphyxia, and hemorrhagic shock. Total RNAs were extracted from myocardium. The quantitative real time PCR was used to calculate threshold cycle values of RNAs including glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-actin, inducible nitric oxide synthase (iNOS), hypoxia-inducible factor-1 (HIF-1), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and U6 small nuclear RNA (U6 snRNA) and to study the changes of the relative expressions of various indexes with PMI. RESULTS: U6 snRNA with stable expression level could be used as appropriate internal control. In the early PMI, the relative expression of GAPDH, HIF-1, iNOS, TNF-alpha, and IL-6 more characteristically increased in groups of asphyxia and hemorrhagic shock than in group of broken neck, but the quantity of beta-actin decreased in all groups. In the late PMI, all the relative expressions significantly declined in correlation with the degradation of RNA. CONCLUSION: The characteristic changes of each RNA expression can be used as references to estimate PMI in deaths by different causes.

A time course study demonstrating mRNA, microRNA, 18S rRNA, and U6 snRNA changes to estimate PMI in deceased rat's spleen.

Determining the postmortem interval (PMI) is important in criminal, civil, and forensic cases. We examined the feasibility of using the transcript abundances of mRNAs, 18S rRNA, U6 snRNA, and microRNAs as a means to estimate the PMI. We removed spleen tissues from rats at different PMIs under 4°C or 25°C and examined gene transcript abundances in these samples by RT-qPCR. Using the algorithm geNorm, we found that microRNAs to be appropriate control markers because they were less affected by PMI and temperature. We also characterized relationships between observed PMI and the transcript levels of the above-mentioned RNAs. GAPDH1 and ACTB1 fluctuated slightly like cubic curves, while GAPDH2 and ACTB2 decreased rapidly. 18S rRNA transcript level exhibited a parabolic-like trend at 25°C and exponential growth at 4°C, while U6 transcript level exhibited exponential decay at 25°C and a parabolic-like trend at 4°C. Following validation, we conclude that GAPDH2, ACTB2, and 18S rRNA are suitable makers in the accurate determination of PMI.