Accurate and objective estimation of the postmortem interval (PMI) is crucial in forensic practice. This study aimed to infer PMI through equations based on the relationship between PMI and metabolomics biomarkers.Rats were subjected to models representing various temperatures and causes of death, with blood collected at different intervals. Untargeted gas chromatographymass spectrometry metabolomics detection methods were developed, and candidate biomarkers were chosen as co-differentially expressed metabolites in four models. A targeted method was then developed for quantitatively determining candidate biomarkers. Animal tests and human cadaver samples with clearly documented causes of death and time were used to verify the reliability of the regression equation.Results: Unique differential metabolites for CO poisoning deaths included 2,3-butanediol, hypoxanthine, and dehydrated hexanol, while those for mechanical asphyxia deaths comprised propylamine, 1,3-propylene glycol, phosphoric acid, and sorbitol. Pyruvate, glycerol and isoleucine were identified as candidate biomarkers. Human case results demonstrated the method\'s potential (error rate < 20 %). The findings of this study may offer reference points for estimating PMI and causes of death in forensic practice.

To study the degradation of lncRNAs in EPMI in rat brain tissue, this study provides a new direction for the estimation of EPMI. LncRNA high-throughput sequencing was performed on the brain tissues of hemorrhagic shock model rats at 0 h and 24 h, and the target lncRNAs were screened. Samples at 0, 1, 3, 6, 12, 18 and 24 h after death were collected, and miRNA-9 and miRNA-125b were used as reference genes. The relative expression levels of lncRNAs at each PMI were detected by RT-qPCR, and a functional model involving lncRNAs and EPMI was established. Samples were collected at 6, 9, 15, and 21 h after death for functional model verification. The expression of several lncRNAs decreased with the prolongation of EPMI, and the mathematical model established by several lncRNA indices exhibited good fit. The verification results of the multi-index joint function model are significantly better than those of the single-index function model, and the established model is more practical. There is a linear relationship between lncRNAs and EPMI, and the multi-index function model is significantly better than the single-index function model, which is important for EPMI inference in forensic pathology practice.

In the process of murder investigation, it is of great significance to find the discarded and buried human remains accurately. The main methods of searching for human remains include human visual search, aerial detection, geophysical technology, remote imaging technology and canine olfactory search technique. Canine olfactory search for human remains is a recognized time-effective and non-invasive search method, making dogs the most valuable search tool in forensic investigation. By systematically reviewing and summarizing relevant literature, and based on the theory of volatile organic compound produced by the decomposition of human remains, this paper explores the basic principle of the canine olfactory search technique for human remains. This paper also reviews the application of training canine search technique for human remains in forensic investigation by using human blood, tissue, cadaver putrefying fluid and odor substitutes as sniffing sources. The application prospect of canine olfactory search for human remains was prospected from the perspectives of detection of volatile organic compound during cadaver decay, development of odor substitutes and adsorption devices, and technology tactics used in canine training and use, to provide references for the relevant research of canine olfactory search for human remains in China.
命案侦查过程中，准确找到被丢弃、掩埋的人体遗骸至关重要。寻找人体遗骸的方法主要有人类的视觉搜索、空中探测、地球物理技术、远程成像技术以及犬类嗅觉搜索技术等。犬类嗅觉搜索人体遗骸技术是一种公认的具有时效性的非侵入性搜索方法，是法医调查中最有价值的搜索工具。本文通过系统查阅和总结相关文献资料，以人体遗骸分解产生的挥发性有机化合物为理论基础，探寻犬类嗅觉搜索人体遗骸技术的基本原理，对以人类血迹、人体组织、尸体腐败液、气味替代物作为嗅源训练犬类搜索人体遗骸技术在法医调查中的使用进行综述，从尸体腐败过程中挥发性有机化合物的检测、气味替代物和吸附装置的研发、犬类训练与使用的技战法等角度展望犬类嗅觉搜索人体遗骸技术的应用前景，以期为我国犬类嗅觉搜索人体遗骸技术的相关研究提供参考。.

To reveal the interaction of oxidative stress and protein S-nitrosylation on mitochondrial pathway apoptosis and tenderness development in postmortem yak meat. Herein, we selected yak longissimus dorsi muscle as the research object and treated hydrogen peroxide (H2O2) with S-nitrosoglutathione agent (GSNO) as well as Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) in mixed injections with 0.9 % saline as a control group, followed by incubation at 4 °C for 12, 24, 72, 120 and 168 h. Results showed that this interaction significantly increased mitochondrial ROS and NO content (P < 0.05) while weakening the antioxidant capacity of GSH and TRX redox response systems or accelerating the Ca2+ release process, leading to mitochondrial functional impairment and increased apoptosis rate. Notably, the H2O2 + L-NAME group showed more pronounced apoptosis. Hence, we suggest that the interaction between oxidative stress and protein S-nitrosylation could positively regulate yak meat tenderization.

Necrophagous beetles are sometimes used to estimate the minimum postmortem interval (PMImin) in the decay and remains stages of a corpse. Among these, the Dermestidae is one of the most common groups used and therefore has important research and application value. In this study, the developmental events of Dermestes maculatus de Geer, 1774, were recorded at six constant temperatures, and isomorphen diagrams were established. The thermobiological parameters were estimated using linear and non-linear models, and morphological indicators such as larval body length were measured. The results showed that the developmental duration of the whole immature stage decreased from 66.13 ± 8.58 days at 19 °C to 21.9 ± 2.01 days at 34 °C. The survival rate of the immature stages, especially the egg stage, varies greatly with temperature, with the lowest survival observed at 34 °C and the highest at 22 °C. The lower developmental threshold, the intrinsic optimum temperature, and the upper lethal developmental threshold obtained by the curvilinear Optim SSI models were 15.28 °C, 28.36 °C, and 34.03 °C, respectively. The body length, head capsule width, and pronotum width showed obvious growth patterns with larval developmental duration, which were characterized by equations and isomegalen diagrams. This study provides important basic data for the application of D. maculatus to estimate the PMImin in forensic entomology in the Yangtze River Delta region of China.

The weathering time of empty puparia could be important in predicting the minimum postmortem interval (PMImin). As corpse decomposition progresses to the skeletal stage, empty puparia often remain the sole evidence of fly activity at the scene. In this study, we used empty puparia of Sarcophaga peregrina (Diptera: Sarcophagidae) collected at ten different time points between January 2019 and February 2023 as our samples. Initially, we used the scanning electron microscope (SEM) to observe the surface of the empty puparia, but it was challenging to identify significant markers to estimate weathering time. We then utilized attenuated total internal reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to detect the puparia spectrogram. Absorption peaks were observed at 1064 cm-1, 1236 cm-1, 1381 cm-1, 1538 cm-1, 1636 cm-1, 2852 cm-1, 2920 cm-1. Three machine learning models were used to regress the spectral data after dimensionality reduction using principal component analysis (PCA). Among them, eXtreme Gradient Boosting regression (XGBR) showed the best performance in the wavenumber range of 1800-600 cm-1, with a mean absolute error (MAE) of 1.20. This study highlights the value of refining these techniques for forensic applications involving entomological specimens and underscores the considerable potential of combining FTIR and machine learning in forensic practice.

Research conducted previously has demonstrated that apoptosis significantly influences the chicken quality. While ROS are acknowledged as significant activators of apoptosis, the precise mechanism by which they influence muscle cell apoptosis in the post-mortem remains unclear. In this study, chicken samples were treated with rosemarinic acid and H2O2 to induce varying ROS levels, and the ROS-triggered apoptosis mechanism in chicken muscle cells in post-mortem was analyzed. The TUNEL results revealed that elevated ROS levels in chicken were associated with a greater degree of muscle cell apoptosis. Western-blot results suggested that sarcoplasmic ROS could initiate apoptosis through the mitochondrial pathway by activating the MAPK-JNK signaling pathway. Moreover, TEM and shear force results demonstrated that muscle cell apoptosis initiates myofiber fragmentation and structural damage to sarcomeres, ultimately reducing chicken tenderness. This study enhances our understanding of post-mortem muscle cell apoptosis, providing valuable insights for regulating chicken quality.

OBJECTIVE: To explore the postmortem diffusion rule of Aconitum alkaloids and their metabolites in poisoned rabbits, and to provide a reference for identifying the antemortem poisoning or postmortem poisoning of Aconitum alkaloids.
METHODS: Twenty-four rabbits were sacrificed by tracheal clamps. After 1 hour, the rabbits were administered with aconitine LD50 in decocting aconite root powder by intragastric administration. Then, they were placed supine and stored at 25 ℃. The biological samples from 3 randomly selected rabbits were collected including heart blood, peripheral blood, urine, heart, liver, spleen, lung and kidney tissues at 0 h, 4 h, 8 h, 12 h, 24 h, 48 h, 72 h and 96 h after intragastric administration, respectively. Aconitum alkaloids and their metabolites in the biological samples were analyzed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).
RESULTS: At 4 h after intragastric administration, Aconitum alkaloids and their metabolites could be detected in heart blood, peripheral blood and major organs, and the contents of them changed dynamically with the preservation time. The contents of Aconitum alkaloids and their metabolites were higher in the spleen, liver and lung, especially in the spleen which was closer to the stomach. The average mass fraction of benzoylmesaconine metabolized in rabbit spleen was the highest at 48 h after intragastric administration. In contrast, the contents of Aconitum alkaloids and their metabolites in kidney were all lower. Aconitum alkaloids and their metabolites were not detected in urine.
CONCLUSIONS: Aconitum alkaloids and their metabolites have postmortem diffusion in poisoned rabbits, diffusing from high-content organs (stomach) to other major organs and tissues as well as the heart blood. The main mechanism is the dispersion along the concentration gradient, while urine is not affected by postmortem diffusion, which can be used as the basis for the identification of antemortem and postmortem Aconitum alkaloids poisoning.
目的: 探究乌头生物碱及其代谢物在中毒家兔体内的死后弥散规律，为乌头生物碱中毒相关死亡案件生前服毒或死后染毒的判别提供参考依据。方法: 将24只家兔经气管夹闭处死1 h后，以生川乌水煎液灌胃（以生川乌水煎液中乌头碱的LD50计算）。灌胃后将家兔以仰卧位保存于25 ℃气候箱中，分别于0 h、4 h、8 h、12 h、24 h、48 h、72 h、96 h随机各取3只进行解剖，取心血、外周血、尿液、心脏、肝、脾、肺和肾组织，采用高效液相色谱-串联质谱法对乌头生物碱及其代谢物在各生物检材中的含量进行检测。结果: 灌胃后4 h，乌头生物碱及其代谢物在心血、外周血和主要器官组织中均可检出，且含量随保存时间的延长发生动态变化。其中，脾、肝和肺中乌头生物碱及其代谢物含量均较高，尤其距离胃较近的脾中乌头生物碱及其代谢物含量最高。灌胃后48 h，家兔脾中代谢物苯甲酰新乌头原碱的平均质量分数最高；肾中乌头生物碱及其代谢物含量均偏低；尿液中未检出乌头生物碱及其代谢物。结论: 乌头生物碱及其代谢物在中毒家兔体内存在死后弥散现象，且从含量高的器官（胃）扩散到其他主要器官组织及心血中，其主要机制是顺浓度梯度的弥散，而尿液不受死后弥散的影响，可考虑将其作为乌头生物碱生前服毒和死后染毒的鉴别依据。.

In forensic practice, determining the postmortem submersion interval (PMSI) and cause-of-death of cadavers in aquatic ecosystems has always been challenging task. Traditional approaches are not yet able to address these issues effectively and adequately. Our previous study proposed novel models to predict the PMSI and cause-of-death based on metabolites of blood from rats immersed in freshwater. However, with the advance of putrefaction, it is hardly to obtain blood samples beyond 3 days postmortem. To further assess the feasibility of PMSI estimation and drowning diagnosis in the later postmortem phase, gastrocnemius, the more degradation-resistant tissue, was collected from drowned rats and postmortem submersion model in freshwater immediately after death, and at 1 day, 3 days, 5 days, 7 days, and 10 days postmortem respectively. Then the samples were analyzed with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to investigate the dynamic changes of the metabolites. A total of 924 metabolites were identified. Similar chronological changes of gastrocnemius metabolites were observed in the drowning and postmortem submersion groups. The difference in metabolic profiles between drowning and postmortem submersion groups was only evident in the initial 1 day postmortem, which was faded as the PMSI extension. Nineteen metabolites representing temporally-dynamic patterns were selected as biomarkers for PMSI estimation. A regression model was built based on these biomarkers with random forest algorithm, which yielded a mean absolute error (± SE) of 5.856 (± 1.296) h on validation samples from an independent experiment. These findings added to our knowledge of chronological changes in muscle metabolites from submerged vertebrate remains during decomposition, which provided a new perspective for PMSI estimation.

This paper aimed to investigate the effects of ultrasound-assisted L-lysine treatment on meat quality and myofibrillar proteins (MPs) properties of pork longissimus dorsi during postmortem aging. The results revealed that the L-lysine (Lys) and/or ultrasound treatment significantly increased (p < 0.05) the water-holding capacity and tenderness of the pork during postmortem aging, while the ultrasound-assisted Lys treatment had the lowest cooking loss, pressurization loss, Warner-Bratzler shear force, and hardness. In addition, L-lysine and/or ultrasound treatment increased (p < 0.05) pH value, T21, and myofibrillar fragmentation index, while the ultrasound-assisted Lys treatment had the highest value. Meanwhile, the protein solubility was increased with Lys and/or ultrasound treatment during postmortem aging, and ultrasound-assisted Lys treatment had the highest solubility, reaching 88.19%, 92.98%, and 91.73% at 0, 1, and 3 days, respectively. The result of protein conformational characteristics showed that Lys and/or ultrasound treatment caused the unfolding of the α-helix structure, resulting in the exposure of more hydrophobic amino acids and buried sulfhydryl groups, ultimately enhancing MPs solubility. In summary, ultrasound-assisted Lys treatment altered the structure of MPs, resulting in the enhancement of the water-holding capacity and tenderness of the pork. PRACTICAL APPLICATION: This study showed that ultrasound-assisted L-lysine (Lys) treatment could enhance the water-holding capacity and tenderness of pork during postmortem aging. The results might provide a reference for the application of ultrasound-assisted Lys treatment on the improvement of pork meat quality. To facilitate practical applications in production, the development of medium and large-sized ultrasound equipment for conducting small-scale and pilot experiments is crucial for future research.