法医学杂志最新文献

Objectives: To compare the application effects of plankton multiplex polymerase chain reaction-capillary electrophoresis (PCR-CE), SYBR Green Ⅰ real-time quantitative PCR (qPCR) and microwave digestion-vacuum filtration-automated scanning electron microscopy (MD-VF-Auto SEM) in the diagnosis of drowning.

Methods: Lung, liver and kidney tissues from 212 drowned corpses and 30 non-drowned corpses were examined respectively by the three drowning-related plankton testing methods, and the detection rates of plankton in each tissue by three methods were compared.

Results: In drowned corpses, the total detection rates of PCR-CE, qPCR, and MD-VF-Auto SEM were 93.9%, 96.2%, and 95.3%, respectively, with no statistically significant difference (P>0.05). The detection rate of lung tissue by MD-VF-Auto SEM (100%) was higher than those of PCR-CE and qPCR (P<0.05), and there was no significant difference in the detection rates of the three methods in liver or kidney tissues (P>0.05). In non-drowning corpses, a small number of diatoms (less than 10 cells/10 g) were detected by MD-VF-Auto SEM method, only in liver and kidney tissues, while the other two methods yielded negative results for all tissues.

Conclusions: All three methods have good efficacy in the examination of drowned corpses. The MD-VF-Auto SEM method directly observes diatom morphological characteristics through scanning electron microscopy, and the qualitative and quantitative analyses are intuitive and accurate. It has great advantages in the examination of difficult degradation samples. The PCR-CE method and qPCR method have a low sample demand (0.5 g), are easy to operate and have short detection time (4-7 h). They are easy to be applied in the grassroots departments and are suitable for the rapid determination of drowned corpses in routin cases. The combination of the two DNA methods with the MD-VF-Auto SEM method can increase the detection rate of plankton, ensuring the reliability of examination results. This combined use is of significant importance in the application of drowning diagnosis.

Objectives: To verify the efficacy of a domestic human DNA quantification kit based on real-time fluorescence quantitative PCR in detecting the total human DNA concentration, male DNA concentration in mixed male/female DNA samples, the degree of DNA degradation and inhibitor tolerance.

Methods: Samples with different concentrations, different male/female ratios, different concentrations of inhibitors, and different degradation degrees were tested using the domestic human DNA quantification kit based on real-time fluorescence quantitative PCR. This kit was compared with a similar product on the market and was applied to the detection of DNA from real cases.

Results: This human DNA quantification kit can effectively detect human DNA as low as 0.001 65 ng/μL, and 6.25 pg/μL of male DNA in mixed samples with a male-to-female ratio of 1∶15 000. Even when the sample contains as high as 400 ng/μL of humic acid or 1 000 μmol/L of hemin alone, the DNA concentration can still be accurately detected. The degradation index can effectively characterize the degradation degree of the sample. This kit has been successfully applied in forensic practice.

Conclusions: This human DNA quantification kit is accurate and reliable in detection. It can accurately reflect the degradation of DNA and inhibitor tolerance. It has good performance in quantitative accuracy, determination of the male/female ratio in mixed samples, and inhibitor tolerance. It has application potential in forensic case examination.

Objectives: To explore a deep learning network model suitable for bone age estimation using shoulder joint X-ray images in Chinese Han adolescents.

Methods: A retrospective collection of 1 286 shoulder joint X-ray images of Chinese Han adolescents aged 12.0 to <18.0 years (708 males and 578 females) was conducted. Using random sampling, approximately 80% of the samples (1 032 cases) were selected as the training and validation sets for model learning, selection and optimization, and the other 20% samples (254 cases) were used as the test set to evaluate the model's generalization ability. The original single-channel shoulder joint X-ray images and dual-channel inputs combining original images with segmentation labels (manually annotated shoulder joint regions multiplied pixel-by-pixel with original images, followed by segmentation via the U-Net++ network to retain only key shoulder joint region information) were respectively input into four network models, namely VGG16, ResNet18, ResNet50 and DenseNet121 for bone age estimation. Additionally, manual bone age estimation was conducted on the test set data, and the results were compared with the four network models. The mean absolute error (MAE), root mean square error (RMSE), coefficient of determination (R²), and Pearson correlation coefficient (PCC) were used as main evaluation indicators.

Results: In the test set, the bone age estimation results of the four models with dual-channel input of shoulder joint X-ray images outperformed those with single-channel input in all four evaluation indicators. Among them, DenseNet121 with dual-channel input achieved best results with MAE of 0.54 years, RMSE of 0.82 years, R² of 0.76, and PCC (r) of 0.88. Manual estimation yielded an MAE of 0.82 years, ranking second only to dual-channel DenseNet121.

Conclusions: The DenseNet121 model with dual-channel input combined with original images and segmentation labels is superior to manual evaluation results, and can effectively estimate the bone age of Chinese Han adolescents.

Objectives: To detect the expression changes of citrullinated histone H3 (CitH3) during the development of deep vein thrombosis (DVT) in mice, and to explore its value in estimating the time to thrombosis.

Methods: The inferior vena cava (IVC) of mice was ligated to establish a thrombosis model induced by congestion. Mice were sacrificed under excessive anesthesia at 0 h, 1 d, 3 d, 5 d, 7 d, 10 d, 14 d and 21 d after the modeling, respectively. The congested IVC segments (0 h after modeling) and the thrombosed IVC segments (1-21 days after modeling) were extracted. Immunohistochemistry and double immunofluorescence staining were used to observe the number of neutrophils and the expression of CitH3 during thrombosis. Western blotting was used to detect the protein expression level of CitH3.

Results: During thrombosis, CitH3 was mainly expressed in neutrophils within the thrombus. A small number of neutrophils and a few CitH3-positive cells were observed at 0 h after modeling in the congested IVC. Between 1 d and 21 d after modeling, the number of neutrophils reached a peak at 1 d and gradually decreased. The number of CitH3-positive cells and their ratio to neutrophils began to increase at 1 d, reached a peak at 5 d after modeling, and then decreased. The expression level of CitH3 protein began to increase at 1 d and reached a peak at 5 d after modeling.

Conclusions: The expression of CitH3 during DVI shows temporal changes, and is expected to become a biological marker for estimating the formation time of thrombosis.

The inference of tissue origin of body fluid stains is crucial for case investigation and court proceedings. However, traditional methods for identification of body fluid stains, such as morphological, chemical, and immunoassay identifications have certain limitations, and there is an urgent need for more efficient methods for confirmatory experiments. In recent years, the rapid development of transcriptomics technology has provided new means for the identification of tissue origin of body fluid stains. Different types of RNA in the transcriptome have their own advantages. This paper elaborates in detail on the application of different types of RNA, such as mRNA, miRNA, circRNA, lncRNA, piRNA and microbial transcriptomics in body fluid identification, and summarizes their respective advantages and limitations, in order to provide a reference for related research.

Objectives: To investigate the genetic differences among different populations based on 13 autosomal STR loci in CODIS core.

Methods: Data of 13 autosomal STR loci (CSF1PO, FGA, THO1, TPOX, vWA, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11) were collected from 95 populations in scientific journals between 1999 and 2021, soursed from the PubMed database, which had been published. Allele frequencies of loci were sorted out and forensic genetic parameters including gene differentiation coefficient (G_st), total heterozygosity (H_t), subpopulation heterozygosity (H_s) values, and Nei's DA genetic distance were calculated. Principal component analysis, phylogenetic tree, and multidimensional scale analysis were conducted to assess population genetic structure.

Results: A total of 265 alleles were detected at the 13 STR loci in these 95 populations. The mean values of G_st, H_t, and H_s were 0.023 247, 0.797 915 and 0.779 365. Population genetic analyses reflected significant differences among populations from Asia, Africa and Europe. In Asian populations, there was a certain degree of distinction between mainland and island populations; the Han population showed a certain degree of distinction with surrounding populations in mainland; while within the Han population, there were two distinct clusters formed by the northern Han and the southern Han.

Conclusions: The 13 autosomal STR loci in CODIS core demonstrate potential value for population identification across different groups, and may be used for the differentiation of ethnic groups, among different continental populations.