Pathological Characteristics and Classification of Unstable Coronary Atheroscle-rotic Plaques / 法医学杂志

Important forensic diagnostic indicators of sudden death in coronary atherosclerotic heart dis-ease,such as acute or chronic myocardial ischemic changes,sometimes make it difficult to locate the ischemic site due to the short death process,the lack of tissue reaction time.In some cases,the de-ceased died of sudden death on the first-episode,resulting in difficulty for medical examiners to make an accurate diagnosis.However,clinical studies on coronary instability plaque revealed the key role of coronary spasm and thrombosis caused by their lesions in sudden coronary death process.This paper mainly summarizes the pathological characteristics of unstable coronary plaque based on clinical medi-cal research,including plaque rupture,plaque erosion and calcified nodules,as well as the influencing factors leading to plaque instability,and briefly describes the research progress and technique of the atherosclerotic plaques,in order to improve the study on the mechanism of sudden coronary death and improve the accuracy of the forensic diagnosis of sudden coronary death by diagnosing different patho-logic states of coronary atherosclerotic plaques.

Postmortem Interval Estimation Using Protein Chip Technology Combined with Multivariate Analysis Methods / 法医学杂志

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.

Exploration and Practice of the "One Combination, Two Highlights, Three Combinations, Four in One" Innovative Talents Training Mode in Forensic Medicine / 法医学杂志

Talent is one of the basic and strategic supports for building a modern socialist country in all aspects. Since the 1980s, the establishment of forensic medicine major and the cultivation of innovative talents in forensic medicine have become hot topics in higher education in forensic medicine. Over the past 43 years, the forensic medicine team of Shanxi Medical University has adhered to the joint education of public security and colleges, and made collaborative innovation, forming a training mode of "One Combination, Two Highlights, Three Combinations, Four in One" for innovative talents in forensic medicine. It has carried out "5+3/X" integrated reform, and formed a relatively complete talent training innovation mode and management system in teaching, scientific research, identification, major, discipline, team, platform and cultural construction. It has made a historic contribution to China's higher forensic education, accumulated valuable experience for the construction of first-class major and first-class discipline of forensic medicine, and provided strong support for the construction of the national new forensic talent training system. The popularization of this training mode is conducive to the rapid and sustainable development of forensic science, and provides more excellent forensic talents for national building, regional social development and the discipline construction of forensic science.

Research Progress of Automatic Diatom Test by Artificial Intelligence / 法医学杂志

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.

Comparison among Four Deep Learning Image Classification Algorithms in AI-based Diatom Test / 法医学杂志

OBJECTIVES@#To select four algorithms with relatively balanced complexity and accuracy among deep learning image classification algorithms for automatic diatom recognition, and to explore the most suitable classification algorithm for diatom recognition to provide data reference for automatic diatom testing research in forensic medicine.@*METHODS@#The "diatom" and "background" small sample size data set (20 000 images) of digestive fluid smear of corpse lung tissue in water were built to train, validate and test four convolutional neural network (CNN) models, including VGG16, ResNet50, InceptionV3 and Inception-ResNet-V2. The receiver operating characteristic curve (ROC) of subjects and confusion matrixes were drawn, recall rate, precision rate, specificity, accuracy rate and F1 score were calculated, and the performance of each model was systematically evaluated.@*RESULTS@#The InceptionV3 model achieved much better results than the other three models with a balanced recall rate of 89.80%, a precision rate of 92.58%. The VGG16 and Inception-ResNet-V2 had similar diatom recognition performance. Although the performance of diatom recall and precision detection could not be balanced, the recognition ability was acceptable. ResNet50 had the lowest diatom recognition performance, with a recall rate of 55.35%. In terms of feature extraction, the four models all extracted the features of diatom and background and mainly focused on diatom region as the main identification basis.@*CONCLUSIONS@#Including the Inception-dependent model, which has stronger directivity and targeting in feature extraction of diatom. The InceptionV3 achieved the best performance on diatom identification and feature extraction compared to the other three models. The InceptionV3 is more suitable for daily forensic diatom examination.

Comparison of Medical Dispute Resolution Mechanisms in China and Abroad / 法医学杂志

Medical disputes are one of the common problems concerned by the whole world. All countries and regions have established their own medical dispute resolution mechanisms, in accordance with their own national conditions. Medical dispute identification opinions, as one of the important bases for identifying the responsibilities of both doctors and patients, play a pivotal role in the process of dispute settlement. A reasonable medical dispute resolution mechanism and standardized medical dispute identification model can help resolve disputes flexibly and reduce the conflict between doctors and patients. This paper briefly compares the medical dispute resolution mechanism and identification mode of China and several other representative countries (the United States, Britain, France, Germany, Italy, Japan, etc.), and discusses their respective characteristics and shortcomings, to bring some enlightenment to the medical dispute resolution and identification in our country.

Application of Linear Regression Model of Gpnmb Gene in Rat Injury Time Estimation / 法医学杂志

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.

Correlation between the Polymorphism of Coagulation-Related Genes and Lower Extremity Deep Venous Thrombosis / 法医学杂志

Objective To investigate the correlation between the polymorphism of 4 coagulation-related genes, rs1799963 （coagulation factor V gene Leiden）, rs6025 （prothrombin gene G20210A）, rs1042579 （thrombomodulin protein gene c.1418C>T） and rs1801131 （methylenetetrahydroflate reductase gene） and lower extremity deep venous thrombosis （LEDVT）. Methods The 4 genotypes mentioned above of 150 LEDVT patients and 153 healthy controls were detected by the kompetitive allele specific polymerase chain reaction （KASP）, then related blood biochemical indicators were collected, binary Logistic regression was established to screen the independent risk factors of LEDVT, and the correlation between polymorphism of 4 coagulation-related genes and LEDVT and its indicators under different genetic modes after adjusting confounding factors were analyzed. Results Five variables, D-dimer, fibrinogen degradation product, homocysteine, sex and age might be the risk factors of LEDVT. These variables were put into 4 genetic inheritance models, and adjusted in binary Logistic regression. The results suggested that the mutations of rs1042579 were correlated with LEDVT under dominant inheritance mode. Conclusion The gene polymorphism of rs1799963, rs6025 and rs1801131 has no significant correlation with the formation of LEDVT. The gene polymorphism of rs1042579 plays a role under dominant inheritance mode, and might be an independent risk factor for formation of LEDVT.

Application Prospects and Prospect of Metabolomics in the Identification of Sudden Cardiac Death / 法医学杂志

In cases of sudden death, the prevention of sudden cardiac death and the analysis of the cause of death after sudden cardiac death have always been a difficult problem. Therefore, clinical research and forensic pathological identification of sudden cardiac death are of great significance. In recent years, metabolomics has gradually developed into a popular field of life science research. The detection of "metabolic fingerprints" of biological fluids can provide an important basis for early diagnosis of diseases and the discovery of potential biomarkers. This article reviews the current research status of sudden cardiac death and the research on metabolomics of cardiovascular diseases that is closely related to sudden cardiac death and analyzes the application prospects of metabolomics in the identification of the cause of sudden cardiac death.

Estimating Postmortem Interval Using Intestinal Microbiota Diversity Based on 16S rRNA High-throughput Sequencing Technology / 法医学杂志

OBJECTIVES@#To explore the correlation between intestinal microbiota and postmortem interval(PMI) in rats by using 16S rRNA high-throughput sequencing technology.@*METHODS@#Rats were killed by anesthesia and placed at 16 ℃, and DNA was extracted in caecum at 14 time points of 0, 1, 2, 3, 5, 7, 9, 12, 15, 18, 21, 24, 27 and 30 d after death. The 16S rRNA high-throughput sequencing technology was used to detect intestinal microbiota in rat cecal contents, and the results were used to analyze the rat intestinal microbiota diversity and differences.@*RESULTS@#The total number of intestinal microbial communities did not change significantly within 30 days after death, but the diversity showed an upward trend. A total of 119 bacterial communities were significantly changed at 13 time points after death. The models for PMI estimation were established by using partial least squares (PLS) regression at all time points, before 9 days and after 12 days, reaching an R2 of 0.795, 0.767 and 0.445, respectively; and the root mean square errors (RMSEs) were 6.57, 1.96 and 5.37 d, respectively.@*CONCLUSIONS@#Using 16S rRNA high-throughput sequencing technology, the composition and structure of intestinal microbiota changed significantly within 30 d after death. In addition, the established PLS regression model suggested that the PMI was highly correlated with intestinal microbiota composition, showing a certain time series change.

Expression of Autophagy-Associated Protein in Rat Muscle Tissues after Antemortem and Postmortem Injury / 法医学杂志

Objective To study the expression of the three autophagy-associated proteins, BECN1, LC3 and p62, after the injury of the skeletal muscle of rats and to explore its application in differentiation between antemortem and postmortem injury. Methods The 72 healthy Sprague-Dawley rats were randomly divided into the undamaged control group, the antemortem injury group （0.5 h, 1 h, 2 h, 4 h, 8 h, 16 h and 24 h） and postmortem injury group （0.5 h, 1 h, 2 h and 4 h）. A model of the injured right hind limb of rats was constructed. The expressions of the autophagy-associated proteins, BECN1, LC3-2/LC3-1 and p62, in the control group, the antemortem injury group and postmortem injury group were detected by Western blotting method. The data were respectively centralized and standardized and the orthogonal partial least square-discrimination analysis （OPLS-DA） identification model of antemortem and postmortem injury groups was constructed. Results The expression of BECN1, p62 protein and LC3-2/LC3-1 after the injury of the skeletal muscle of the rats showed different degrees of changes, but the differences among the 3 groups had no statistical significance. Antemortem and postmortem injury groups can be distinguished by centralizing and standardizing the expression levels of autophagy protein BECN1 and the ratio of LC3-2/LC3-1. The principal components extracted from OPLS-DA model of antemortem injury and postmortem injury had a relatively good interpretation of the model （Rx2=0.563, Ry2=0.439）, but it were less predictive （Q2=0.366）. Conclusion The expression of BECN1 and the ratio of LC3-2/LC3-1 in injured local tissue of the rat skeletal muscle can be used for the differentiation of antemortem injury group and postmortem injury group.

Determination of Escitalopram in Biological Samples by Dispersive Liquid-Liquid Microextraction Combined with GC-MS/MS / 法医学杂志

Objective To establish a method for determination of escitalopram in biological samples by ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with gas chromatography-tandem mass spectrometry （GC-MS/MS） and provide evidences for forensic determination of cases related to escitalopram. Methods The 1-hexyl-3-methylimidazolium hexafluorophosphate （[C6MIM][PF6]） was selected as an extract solvent to process biological samples. Ultrasound-assisted extraction was used on the samples. Then the samples were detected by GC-MS/MS. Results The linear range of escitalopram in blood and liver were 5.56-1 111.10 ng/mL and 0.025-5.00 mg/g, respectively. The correlation coefficient （r） were greater than 0.999, limit of detection （LOD） were 4.00 ng/mL and 2.00 μg/g, limit of quantitation （LOQ） were 14.00 ng/mL and 6.00 μg/g, respectively. The extraction recovery rates were all greater than 50%, the interday and intraday precision were less than 20%. Escitalopram was detected in blood and liver samples from the actual poisoning case by this method with a content of 1.26 μg/mL and 0.44 mg/g, respectively. Conclusion The ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with GC-MS/MS is environment friendly, rapid, has good enriching effect and consumes less organic solvent and can be used for forensic determination of escitalopram related cases.

Establishment of Mathematical Models for Skeletal Age Determination of Extremitas Sternalis of Clavicle in Shanxi Adolescents / 法医学杂志

Objective To develop mathematical models for skeletal age determination with multiple statistic method based on the correlation between age and the growth of the epiphysis of extremitas sternalis of clavicle in Shanxi adolescents. Methods The 562 Shanxi sternoclavicular joint samples （454 cases of modelling, 108 cases of external verification） were scanned by the thin-section computed tomography. After volume rendering was obtained, indicators such as area of epiphysis, area of metaphysis, longest diameter of epiphysis and longest diameter of metaphysis of both extremitas sternalis of clavicle were collected. Indicators such as the ratio of area of epiphysis to area of metaphysis, and the ratio of longest diameter of epiphysis to longest diameter of metaphysis of both sides were calculated. Then multiple linear regression and random forest discriminant models were used to build mathematical models for age determination of adolescents. Results The obtained indicators exhibited a strong correlation with age （r>0.85）. The multiple linear regression model for males and females （all 4 indicators entering the model） based on the ratio of longest diameter of epiphysis to longest diameter of metaphysis and the ratio of area of epiphysis to area of metaphysis had an internal validation accuracy rate （±1.0 year） of over 92% and 108 cases had an external validation accuracy rate of over 70% （±1.0 year）. The out of bag error rates of random forest discriminant models were less than 2% for people over 18.0 years old （≥18.0 years old） and under 18.0 years old. The external validation accuracy rates of the 108 cases were over 80%. Conclusion The regression and discriminant models established in this study have certain reliability and accuracy and can be used in age determination of Shanxi adolescents.

Estimating Postmortem Interval by Protein Chip Detection Technology Combined with Multidimensional Statistics / 法医学杂志

Objective To obtain the protein expression profile of rat liver tissue after death by the 2100 bioanalyzer combined with protein chip, and infer the relationship between protein expression profile and postmortem interval. Methods Rats were killed by abdominal anesthesia and placed at 16 ℃. Water-soluble proteins in liver tissues were extracted at 14 time points after death. The expression profile data of proteins with relative molecular weight of 14 000-230 000 were obtained using protein chip, and principal component analysis （PCA）, partial least squares-discriminant analysis （PLS-DA） and Fisher discriminant were used to analyze the data. Results According to the changes of protein expression profile, the postmortem interval was divided into group A （0 d）, group B （1-9 d）, group C （12-30 d） according to the result of PLS-DA. The prediction accuracy of the training set and test set of the model were all 100.0%, and the internal cross-validation of the training set was 100.0% according to Fisher discriminant. The Fisher discriminant model at each time point of group B and C was established to narrow the time window of postmortem interval estimation. The prediction accuracy of the training set and test set were all 100.0%, and the internal cross-validation accuracy of the training set was 100.0% in group B. The prediction accuracy of the training set and test set were respectively 95.2% and 78.6% in group C, and the internal cross-validation of the training set was 88.1%. Conclusion Protein chip detection technology can quickly and easily obtain the expression profile of water-soluble proteins of rat liver tissue with a relative molecular weight of 14 000-230 000 at different time points after death. PLS-DA and Fisher discriminant models are established to classify and predict the postmortem interval, in order to provide new ideas and methods for postmortem interval estimation.

Combination of mRNA of Repair-related Genes in Rat Skeletal Muscles for Wound Age Estimation / 法医学杂志

Objective To investigate the estimation of early and mid-term wound age by a combination of four mRNAs, the DNA polymerase delta-interacting protein 3 （POLDIP3） mRNA, regulator of chromosome condensation 1 like （RCC1L） mRNA, proline-rich 5 （PRR5） mRNA, and ribonucleic acid export 1 （RAE1） mRNA in rats skeletal muscles. Methods The model of rat skeletal muscle contusion was established, and then contusion area muscle tissue was extracted 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44 and 48 h after injury. Histomorphological changes during the repair process after rat skeletal muscle contusion were observed. The relative expressions of Poldip3, Rcc1l, Prr5 and Rae1 mRNAs were detected by reverse transcription real-time quantitative polymerase chain reaction （RT-qPCR）. Different stages of wound age were classified by using the expression patterns of four genes at various time points after injury. The accuracy of the results was verified by Fisher discriminant analysis. Results Histomorphological results showed that the repair process after skeletal muscle contusion occurred with the prolonging of time. Through combination of the expression trends of the four kinds of mRNAs, the 48 h after injury could be divided into three periods, 4-12 h, 16-28 h and 32-48 h. The Fisher discrimination method showed that the classification accuracy rates of the three periods were 83.3%, 75.0% and 73.3%, respectively. Conclusion The classification discrimination based on the relative expression of every gene has a higher accuracy, and the accuracy of wound age estimation with combination of mRNA relative expressions is higher than that with a single indicator. By combining with Fisher discrimination method, this method can be used for early and mid-term wound age estimation.

Wound Age Estimation by Neutrophil Migration Distance / 法医学杂志

Objective To explore the application of neutrophil migration distance for wound age estimation of skeletal muscles in rats, and to provide methodological basis for follow-up study in future. Methods The skeletal muscle contusion model was established in rats, and the control group and the 2, 4, 6 h post-traumatic groups were set. The law of response of neutrophils that participated in the inflammation after injury was detected by immunohistochemical staining, and the relationship between neutrophil migration distance and injury time was detected by TissueFAXS PLUS software. Results The skeletal muscle was obviously infiltrated with neutrophils 2-6 h after injury. The positive rate of neutrophil was （28.75±0.94）% at 2 h post-traumatic, and reached the peak （45.50±3.63）% at 4 h post-traumatic, then decreased to （31.92±1.56）% at 6 h post-traumatic. The neutrophil migration distances increased with the progress of inflammation, and reached （124.80±12.32） μm, （229.03±21.45） μm and （335.04±16.75） μm at 2 h, 4 h and 6 h, respectively. Conclusion There is a relationship of neutrophil infiltrated number and migration distance and wound age within the 2-6 h after skeletal muscle injury, which could be used for the inference of skeletal muscle wound age.

Effects of Temperature on FTIR Spectral Characteristics of Renal Tissue in Rats after Death / 法医学杂志

OBJECTIVES@#To analyse the Fourier transform infrared （FTIR） spectral data of renal tissue at different temperatures in rats after death, and to explore the effects of temperature on the FTIR spectral characteristics of renal tissue.@*METHODS@#The rats were sacrificed by cervical dislocation and placed at 4 ℃, 20 ℃ and 30 ℃. The FTIR spectral data of renal tissue were collected at different time points and analysed by data mining method.@*RESULTS@#The principal component analysis （PCA） results showed that there were significant trends of clustering in the samples of partial time point at 4 ℃, 20 ℃ and 30 ℃. Partial least square （PLS） regression models were established with the spectral data at three temperature groups. The performance of PLS regression models in 20 ℃ and 30 ℃ groups were more superior than that in 4 ℃ group, and the stability of the model in 20 ℃ group was better than that in 30 ℃ group.@*CONCLUSIONS@#There are differences in the FTIR spectral characteristics of renal tissue of rats after death at different temperatures. Temperature has a major impact on the performance of FTIR spectral PLS regression model. Therefore, in order to improve the accuracy of postmortem interval estimation, the effects of temperature on the model should be considered in the related study by spectral method.

Study on Urinary Metabolic Profile in Rats with Deep Venous Thrombosis Based on Pattern Recognition / 法医学杂志

OBJECTIVES@#To study the urinary metabolic profile in rats with deep venous thrombosis （DVT） based on metabolomics and to screen out small molecular biomarkers for the diagnosis and forensic identification of DVT.@*METHODS@#Inferior vena cava of rats was ligated to construct DVT models. The rats were randomly divided into three groups： DVT, sham, and control groups, 10 in each group. The urine of DVT and sham rats was collected during 24 hours in the metabolic cage at 48 hours after operating, meanwhile, 24 hours urine was collected in control group. The metabolic profile was analyzed by nuclear magnetic resonance. SIMCA-P 14.1 software was used for pattern recognition. The variable importance in projection （VIP） value from orthogonal PLS-DA （OPLS-DA） model combined with Mann-Whitney U test were used to search the different metabolites in the urine.@*RESULTS@#The metabolic profiles of urine from DVT, sham, and control groups had significant differences. The DVT, sham, and control groups could be distinguished by the partial least squares method-discriminant analysis （PLS-DA） model. Compared with the urine of the rats in control groups, the levels of leucine, glutamine, creatine, creatinine and sucrose in the urine of DVT rats were up-regulated, and the levels of 3-hydroxybutyrate, lactate, acetone, α-oxoglutarate, citrate and hippurate were down-regulated.@*CONCLUSIONS@#The different metabolites in the urine of DVT rats are expected to become its candidate biomarkers. The results can provide a research basis for the diagnosis, treatment and forensic identification of DVT.

Homogeneity of Different Functional mRNA Indicators for Wound Age Estimation / 法医学杂志

OBJECTIVES@#To explore the homogeneity level of four different functional mRNA （PUM2, TAB2, Cx45 and CHRNA1） expressions in rats with skeletal muscle contusion.@*METHODS@#The relative expressions of PUM2, TAB2, Cx45 and CHRNA1 mRNAs were detected by quantitative real-time reverse transcription-polymerase chain reaction （RT-qPCR）. The coefficient of variation （CV） of the relative expressions for different individuals in each injury group was calculated. The extreme value of CV, cumulative variability, and CVCV were compared.@*RESULTS@#A high CV of PUM2 and TAB2 mRNAs appeared on several different time points. However, the CV of Cx45 and CHRNA1 mRNAs was relatively low. The cumulative variability from high to low was PUM2, CHRNA1, TAB2 and Cx45 mRNAs. The relative expression of PUM2 mRNA was significantly higher than that of TAB2, Cx45 and CHRNA1 mRNAs （ P<0.05）. There was no statistical significance （P>0.05） in the CVCV of the relative expression of TAB2, CHRNA1 and Cx45 mRNAs.@*CONCLUSIONS@#As the mRNAs involving in biological process regulation, PUM2 and CHRNA1 mRNAs show a lowest individual homogeneity of the relative expression followed by TAB2 mRNA. As the mRNAs participating in the composition of cellular structure, Cx45 and CHRNA1 mRNAs show a high individual homogeneity of the relative expressions. The functional classification should be considered for the screening of the mRNA indicators used for wound age estimation.

Establishment of the Mathematical Model for PMI Estimation Using FTIR Spec-troscopy and Data Mining Method / 法医学杂志

Objective To analyse the relationship between Fourier transform infrared （FTIR） spectrum ofrat's spleen tissue and postmortem interval （PMI） for PMI estimation using FTIR spectroscopy combinedwith data mining method. Methods Rats were sacrificed by cervical dislocation, and the cadavers were placed at 20 ℃. The FTIR spectrum data of rats' spleen tissues were taken and measured at different time points. After pretreatment, the data was analysed by data mining method. Results The absorption peak intensity of rat's spleen tissue spectrum changed with the PMI, while the absorption peak position was unchanged. The results of principal component analysis （PCA） showed that the cumulative contribution rate of the first three principal components was 96%. There was an obvious clustering tendency for the spectrum sample at each time point. The methods of partial least squares discriminant analysis （PLS- DA） and support vector machine classification （SVMC） effectively divided the spectrum samples with different PMI into four categories （0-24 h, 48-72 h, 96-120 h and 144-168 h）. The determination coefficient （R2） of the PMI estimation model established by PLS regression analysis was 0.96, and the root mean square error of calibration （RMSEC） and root mean square error of cross validation （RMSECV） were 9.90 h and 11.39 h respectively. In prediction set, the R2 was 0.97, and the root mean square error of prediction （RMSEP） was 10.49 h. Conclusion The FTIR spectrum of the rat's spleen tissue can be effectively analyzed qualitatively and quantitatively by the combination of FTIR spectroscopy and data mining method, and the classification and PLS regression models can be established for PMI estimation.