Research Progress on Microbial Community Succession in the Postmortem Interval Estimation / 法医学杂志

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.

Metabonomics Analysis of Brain Stem Tissue in Rats with Primary Brain Stem Injury Caused Death / 法医学杂志

OBJECTIVES@#To explore the potential biomarkers for the diagnosis of primary brain stem injury (PBSI) by using metabonomics method to observe the changes of metabolites in rats with PBSI caused death.@*METHODS@#PBSI, non-brain stem brain injury and decapitation rat models were established, and metabolic maps of brain stem were obtained by LC-MS metabonomics method and annotated to the HMDB database. Partial least square-discriminant analysis (PLS-DA) and random forest methods were used to screen potential biomarkers associated with PBSI diagnosis.@*RESULTS@#Eighty-six potential metabolic markers associated with PBSI were screened by PLS-DA. They were modeled and predicted by random forest algorithm with an accuracy rate of 83.3%. The 818 metabolic markers annotated to HMDB database were used for random forest modeling and prediction, and the accuracy rate was 88.9%. According to the importance in the identification of cause of death, the most important metabolic markers that were significantly up-regulated in PBSI group were HMDB0038126 (genipinic acid, GA), HMDB0013272 (N-lauroylglycine), HMDB0005199 [(R)-salsolinol] and HMDB0013645 (N,N-dimethylsphingosine).@*CONCLUSIONS@#GA, N-lauroylglycine, (R)-salsolinol and N,N-dimethylsphingosine are expected to be important metabolite indicators in the diagnosis of PBSI caused death, thus providing clues for forensic medicine practice.

Effects of quorum sensing system lasR/rhlR gene on the expression of foxp3, TGF-β1 and IL-10 of lung tissue in tracheal intubation model rat with Pseudomonas aeruginosa biofilm infection / 解放军医学杂志

Objective To investigate the effects of lasR/rhlR gene on Foxp3, TGF-β1 and IL-10 of lung tissue in rat tracheal intubation model with biofilm infection of Pseudomonas aeruginosa (Ps. aer) wild strain (PAO1) and quorum sensing (QS) deficient strain (ΔlasRΔrhlR). Methods Twenty-one SD rats were randomly assigned into 3 groups (7 each): ΔlasRΔrhlR-treated group, PAO1-treated group and sterile control group. Biofilms (BF) were cultured in vitro, and the BF coated tube (infected respectively with Ps. aer PAO1 strain, ΔlasRΔrhlR strain, or with asepsis) was inserted into the trachea to establish the rat model. The rats were sacrificed on the 7th day after intubation. Colony count of lung tissue homogenate (cfu) and lung HE staining were performed, and IL-10 content in bronchoalveolar lavage fluid (BALF), TGF-β1 in lung tissue, and the expression of Foxp3 mRNA in lung cells were determined. Results The bacterial counts were significantly higher in PAO1 and ΔlasRΔrhlR groups than that in sterile control group, and the counts were obviously higher in PAO1 group (10400.00 ± 6313.70/g lung tissue) than that in ΔlasRΔrhlR group (975.00 ± 559.97/g lung tissue, P<0.05). There was no significant pathological changes in lung tissue in sterile control group, while the bronchi and blood vessels in PAO1 group were infiltrated by a large number of inflammatory cells and complicated with alveolar septum thickening and local abscess and necrosis. The pathological changes were milder in ΔlasRΔrhlR group than in PAO1 group; the expression of Foxp3 mRNA was higher in the two Ps. aer infected groups than that in sterile control group (0.65 ± 0.32), and it was significantly higher in PAO1 group (4.62 ± 1.07) than in ΔlasRΔrhlR group (2.15 ± 1.43, P<0.05). The accumulated optical density value of TGF-β1 was significantly higher in the two Ps. aer infected groups than in sterile control group (3721.66 ± 1412.95), and significantly higher in PAO1 group (65 090.56 ± 33 956.54) than that in ΔlasRΔrhlR group (28 861.99 ± 10 826.96, P<0.05); the level of IL-10 was significantly higher in the two Ps. aer infected groups than in that of sterile control group (57.43 ± 22.13ng/ml), and significantly higher in PAO1 group (188.07 ± 57.01ng/ml) than in ΔlasRΔrhlR group (93.31 ± 17.26ng/ml, P<0.05). Conclusion Ps. aer QS system lasR/rhlR gene may promote inflammation, up-regulate the Foxp3 expression and increase the TGF-β1 and IL-10 levels in lung tissue, which may prompt the protraction and persistence of infection.