OBJECTIVES: To estimate postmortem interval (PMI) by analyzing the protein changes in skeletal muscle tissues with the protein chip technology combined with multivariate analysis methods. METHODS: Rats were sacrificed for cervical dislocation and placed at 16 ℃. Water-soluble proteins in skeletal muscles were extracted at 10 time points (0 d, 1 d, 2 d, 3 d, 4 d, 5 d, 6 d, 7 d, 8 d and 9 d) after death. Protein expression profile data with relative molecular mass of 14 000-230 000 were obtained. Principal component analysis (PCA) and orthogonal partial least squares (OPLS) were used for data analysis. Fisher discriminant model and back propagation (BP) neural network model were constructed to classify and preliminarily estimate the PMI. In addition, the protein expression profiles data of human skeletal muscles at different time points after death were collected, and the relationship between them and PMI was analyzed by heat map and cluster analysis. RESULTS: The protein peak of rat skeletal muscle changed with PMI. The result of PCA combined with OPLS discriminant analysis showed statistical significance in groups with different time points (P<0.05) except 6 d, 7 d and 8 d after death. By Fisher discriminant analysis, the accuracy of internal cross-validation was 71.4% and the accuracy of external validation was 66.7%. The BP neural network model classification and preliminary estimation results showed the accuracy of internal cross-validation was 98.2%, and the accuracy of external validation was 95.8%. There was a significant difference in protein expression between 4 d and 25 h after death by the cluster analysis of the human skeletal muscle samples. CONCLUSIONS The protein chip technology can quickly, accurately and repeatedly obtain water-soluble protein expression profiles in rats' and human skeletal muscles with the relative molecular mass of 14 000-230 000 at different time points postmortem. The establishment of multiple PMI estimation models based on multivariate analysis can provide a new idea and method for PMI estimation.
Animals ; Humans ; Rats ; Multivariate Analysis ; Postmortem Changes ; Protein Array Analysis ; Technology

OBJECTIVES: To investigate the concentration and change characteristics of 1, 5-anhydroglucitol (1, 5-AG) in the vitreous humor of rabbit cadavers with hyperglycemic metabolism, and to explore the value of 1, 5-AG in forensic pathology identification of death caused by hyperglycemic metabolism disorders. METHODS: A diabetic hyperglycemic rabbit model was established by using alloxan. Eighteen rabbits with fasting glucose concentration ≥13.80 mmol/L (experimental group) and 18 healthy rabbits with fasting glucose concentration ≤6.10 mmol/L (control group) were selected. After death from air embolism. The blood samples were collected immediately, and vitreous humor samples were collected at 0 h, 12 h, 24 h and 36 h after death. The concentration of 1, 5-AG in the blood and vitreous humor of rabbits was determined. RESULTS: The blood glucose concentration in the experimental group was (25.10±3.14) mmol/L. At the time of death, there was no significant difference in the concentration of 1, 5-AG in the blood [(0.94±0.20) μg/mL] and in the vitreous humor (0.99±0.05 μg/mL, P>0.05). The concentration of 1, 5-AG in the vitreous humor of the experimental group was lower than that of the corresponding control group at all time points (P<0.05), and there was no significant difference betwwen 1, 5-AG concentration in vitreous humor between earch time point in the experimental group and the control group (P>0.05). Correlation analysis showed that the concentration of 1,5-AG in blood was negatively correlated with blood glucose in both control group and experimental group (control group: r=-0.79, P<0.05; experimental group: r=-0.97, P<0.05). CONCLUSIONS Vitreous humor can replace blood as an effective test sample for 1,5-AG detection. The concentration of 1, 5-AG in rabbit vitreous humor remains stable within 36 hours after death and is not affected by the change of postmortem interval. If the concentration of 1, 5-AG decreases significantly, it indicates the existence of hyperglycemia in rabbits before death.
Animals ; Rabbits ; Blood Glucose/metabolism* ; Postmortem Changes ; Vitreous Body/metabolism* ; Cadaver ; Autopsy

Estimation of postmortem interval (PMI) is one of the important research contents in forensic pathology, and it has always been the focus and hot spot of research work. In recent years, scholars at home and abroad have made some research progress in estimating PMI by using ocular tissue. After death, the changes of cornea, aqueous humor, iris, lens, vitreous humor and retina all show time sequence change rule highly related to PMI. This paper reviews the research progress of PMI estimation based on the morphological, biochemical, molecular and genetic material changes of different ocular tissue structures after death, and discusses the existing problems and development trends.
Humans ; Postmortem Changes ; Time Factors ; Autopsy ; Vitreous Body ; Forensic Pathology

Yeast autolysis affects the flavor and quality of beer. The regulation of yeast autolysis is a need for industrial beer production. Previous studies on brewer's yeast autolysis showed that the citric acid cycle-related genes had a great influence on yeast autolysis. To explore the contribution of isocitrate dehydrogenase genes in autolysis, the IDP1 and IDP2 genes were destroyed or overexpressed in typical lager yeast Pilsner. The destruction of IDP1 gene improved the anti-autolytic ability of yeast, and the anti-autolytic index after 96 h autolysis was 8.40, 1.5 times higher than that of the original strain. The destruction of IDP1 gene increased the supply of nicotinamide adenine dinucleotide phosphate (NADPH) and the NADPH/NADP⁺ ratio was 1.94. After fermentation, intracellular ATP level was 1.8 times higher than that of the original strain, while reactive oxygen species (ROS) was reduced by 10%. The destruction of IDP2 gene resulted in rapid autolysis and a decrease in the supply of NADPH. Anti-autolytic index after 96 h autolysis was 4.03 and the NADPH/NADP⁺ ratio was 0.89. After fermentation, intracellular ATP level was reduced by 8% compared with original strain, ROS was 1.3 times higher than that of the original strain. The results may help understand the regulation mechanism of citric acid cycle-related genes on yeast autolysis and provide a basis for the selection of excellent yeast with controllable anti-autolytic performance.
Humans ; Isocitrate Dehydrogenase/genetics* ; NADP ; Reactive Oxygen Species ; Autolysis ; Adenosine Triphosphate

The postmortem interval (PMI) estimation is a key and difficult point in the practice of forensic medicine, and forensic scientists at home and abroad have been searching for objective, quantifiable and accurate methods of PMI estimation. With the development and combination of high-throughput sequencing technology and artificial intelligence technology, the establishment of PMI model based on the succession of the microbial community on corpses has become a research focus in the field of forensic medicine. This paper reviews the technical methods, research applications and influencing factors of microbial community in PMI estimation explored by using high-throughput sequencing technology, to provide a reference for the related research on the use of microbial community to estimate PMI.
Humans ; Postmortem Changes ; Artificial Intelligence ; Autopsy ; Cadaver ; Microbiota

Autopsy ; Drowning/diagnosis* ; Forensic Pathology ; Humans ; Lung ; Postmortem Changes ; Water

OBJECTIVES: The metabolomics technique of LC-MS/MS combined with data analysis was used to detect changes and differences in metabolic profiles in the vitreous humor of early rat carcasses found in water, and to explore the feasibility of its use for early postmortem submersion interval (PMSI) estimation and the cause of death determination. METHODS: The experimental model was established in natural lake water with 100 SD rats were randomly divided into a drowning group (n=50) and a postmortem (CO₂ suffocation) immediately submersion group (n=50). Vitreous humor was extracted from 10 rats in each group at 0, 6, 12, 18 and 24 h postmortem for metabolomics analyses, of which 8 were used as the training set to build the model, and 2 were used as test set. PCA and PLS multivariate statistical analysis were performed to explore the differences in metabolic profiles among PMSI and causes of death in the training set samples. Then random forest (RF) algorithm was used to screen several biomarkers to establish a model. RESULTS: PCA and PLS analysis showed that the metabolic profiles had time regularity, but no differences were found among different causes of death. Thirteen small molecule biomarkers with good temporal correlation were selected by RF algorithm. A simple PMSI estimation model was constructed based on this indicator set, and the data of the test samples showed the mean absolute error (MAE) of the model was 0.847 h. CONCLUSIONS The 13 metabolic markers screened in the vitreous humor of rat corpses in water had good correlations with the early PMSI. The simplified PMSI estimation model constructed by RF can be used to estimate the PMSI. Additionally, the metabolic profiles of vitreous humor cannot be used for early identification of cause of death in water carcasses.
Animals ; Biomarkers/metabolism* ; Cadaver ; Chromatography, Liquid ; Immersion ; Postmortem Changes ; Rats ; Rats, Sprague-Dawley ; Tandem Mass Spectrometry ; Vitreous Body/metabolism* ; Water/metabolism*

OBJECTIVES: To study the relationship between water temperature and floating time of aquatic cadavers, providing a reference for more precise positioning and searching for floating corpses. METHODS: The floating model of guinea pig after drowning at 17-30 ℃ was established, and the floating times of carcasses were recorded. The collected data of 32 floating corpse cases in the Pearl River were sorted out and analyzed according to the floating time of corpses corresponding to each degree of water temperature. The relationship models between water temperature and the floating time of guinea pig carcass, and between that and the floating time of real cases were established. RESULTS: The floating time of the cadaver was negatively correlated with water temperature. The power function fitting equation of the relationship between floating time and water temperature of guinea pig carcass was y=1×10¹⁵x^-10.530(R²=0.871, P<0.01), and the power function fitting equation of the relationship between corpse floating time and water temperature was y=3×10⁶x^-3.467(R²=0.802, P<0.01). CONCLUSIONS It is found that average floating cadaver time has a power function with water temperature, which provides a reference for locating floating cadavers and establishing search models.
Animals ; Cadaver ; Drowning ; Guinea Pigs ; Postmortem Changes ; Rivers ; Temperature ; Water

The postmortem diagnosis of acute myocardial infarction (AMI), especially the postmortem diagnosis of early AMI that died immediately after onset or within 1 hour, has always been a difficulty in forensic identification. This article reviews the forensic application of diagnosis and analysis methods for AMI postmortem diagnosis including autopsy imaging, histomorphology, immunohisto-chemistry, biochemical marker and molecular biology diagnosis, and explores the feasible scheme of early postmortem diagnosis in AMI.
Autopsy ; Biomarkers ; Forensic Medicine ; Forensic Pathology/methods* ; Humans ; Myocardial Infarction/diagnosis* ; Postmortem Changes

OBJECTIVES: To investigate the effects of injury time, postmortem interval (PMI) and postmortem storage temperature on mRNA expression of glycoprotein non-metastatic melanoma protein B (Gpnmb), and to establish a linear regression model between Gpnmb mRNA expression and injury time, to provide aimed at providing potential indexes for injury time estimation. METHODS: Test group SD rats were anesthetized and subjected to blunt contusion and randomly divided into 0 h, 4 h, 8 h, 12 h, 16 h, 20 h and 24 h groups after injury, with 18 rats in each group. After cervical dislocation, 6 rats in each group were collected and stored at 0 ℃, 16 ℃ and 26 ℃, respectively. The muscle tissue samples of quadriceps femoris injury were collected at 0 h, 12 h and 24 h postmortem at the same temperature. The grouping method and treatment method of the rats in the validation group were the same as above. The expression of Gpnmb mRNA in rat skeletal muscle was detected by RT-qPCR. The Pearson correlation coefficient was used to evaluate the correlation between Gpnmb mRNA expression and injury time, PMI, and postmortem storage temperature. SPSS 25.0 software was used to construct a linear regression model, and the validation group data was used for the back-substitution test. RESULTS: The expression of Gpnmb mRNA continued to increase with the prolongation of injury time, and the expression level was highly correlated with injury time (P<0.05), but had little correlation with PMI and postmortem storage temperature (P>0.05). The linear regression equation between injury time (y) and Gpnmb mRNA relative expression (x) was y=0.611 x+4.489. The back-substitution test proved that the prediction of the model was accurate. CONCLUSIONS The expression of Gpnmb mRNA is almost not affected by the PMI and postmortem storage temperature, but is mainly related to the time of injury. Therefore, a linear regression model can be established to infer the time of injury.
Animals ; Rats ; Glycoproteins ; Linear Models ; Melanoma ; Membrane Glycoproteins/genetics* ; Postmortem Changes ; Rats, Sprague-Dawley ; RNA, Messenger/metabolism* ; Time Factors