Purpose To perform MRI examination after the death of SD rat model due to cerebral infarction and to investigate the changing characteristics of cerebral infarction during postmortem examination. Materials and Methods Middle cerebral artery occlusion (MCAO) model was established on 21 SD rats by applying modified suture method. 13 to 56 h after modeling, 12 dead SD rats were collected for the experiment. The bodies were stored at an environment with a temperature of 10-15°C and relative humidity of 45%-55%. Head MRI was performed 12 h after modeling and at 8, 24, 48, 72 and 96 h after death respectively, and apparent diffusion coefficient (ADC) values of infarction and contralateral brain tissue were calculated. At each post-mortem time point, ADC values of bilateral cerebral hemispheres, ADC values of infarction and living infarction, and ADC values of non-infarcted brain and living non-infarcted zone were compared. Brain tissue was taken after scan for pathological diagnosis and compared with diagnostic results of postmortem MRI (pmMRI). Results The right cerebral signal of rats was abnormal 12 h after cerebral infarction and after death. Eight rats were found to have shifted cerebral middle-line structure to the left. ADC values of infarction at each time point after death were lower than that of non-infarction, the difference of which was statistically significant (P<0.05); ADC values of infarction were lower than that of living infarction, the difference of which was statistically significant (P<0.05); ADC value of non-infarcted area at each time point was lower than that of living non-infarcted area, the difference of which was statistically significant (P<0.05). Necrosis and disintegration of neurons, disintegration and liquefaction of glial fibers, infiltration of inflammatory cells and leakage of red blood cells were spotted in necrotic areas after receiving cerebral HE staining in rat. HE staining was consistent with the infarction zone indicated by pmMRI. Conclusion pmMRI can be used for the diagnosis of cerebral infarction via virtual necropsy.

Objective To study the mechanism of two-component system of MprAB and TrcRS in synergistically regulating gene rv1057 expression of Mycobacterium tuberculosis.Methods The in vivo specific binding capability of MprA and TrcR with the target gene promoter region was analyzed using electrophoretic mobility shift assay.The transcription level of target gene was analyzed by using fluorescence quantitative polymerase chain reaction,and all results were compared with the fold changes in H37Rv strain plus SDS group,which was set as one unit.The expression level of target gene was analyzed by using western blot;the transcription ability of different promoter region of rv1057 was detected through lacZ report gene.The t test was used for statistical analysis.Results MprA was able to bind to trcR promoter.The expressions of trcR in D981 and H37Rv strains without SDS were 1.7 and 2.5 folds of the expression of H37Rv strains with SDS groups,respectively.The difference between these two groups was statistically significant (t=18.54,P＜0.05).With SDS,the expressions of trcR in D981 and H37Rv strains were 1.0 and 2.1 folds of the expression of H37Rv strains plus SDS group,respectively.The expressions of trcR in D981 and H37Rv strains were significantly different (t=15.86,P＜0.05).After adding SDS during the culture of H37Rv strains,the expression of trcR in H37Rv decreased.The difference between these two groups was statistically significant (t=16.99,P＜0.05).Both MprA and TrcR were able to bind to rv1057 promoter and regulate its expression.MprA activated the expression of rv1057,while TrcR repressed the expression of rv1057.Conclusions MprAB and TrcRS synergistically regulate the expression of rv1057.MprA is activated in the presence of SDS,which represses the transcription of trcR and activates the transcription of rv1057.However,TrcR represses the transcription of rv1057 in the absence of SDS.

Type Ⅶ secretion system(T7SS) is a novel and specialized secretion system discovered in recent years. It was first found in Mycobacterium tuberculosis. Type Ⅶ secretion system is involved in the secretion of virulence-associated proteins, the interaction between pathogens and hosts and the balance of zinc/iron ions. Moreover,it plays a critical role in the growth and pathogenesis of Mycobacteria. This review summarizes the components,substrates and translocation mechanisms of the type Ⅶ secretion system and its relation to the virulence of Mycobacteria aiming to provide references for developing novel strategies for disea-ses diagnosis,treatment and prevention.

Stenotrophomonas species are non-fermentative Gram-negative bacteria that are widely distributed in environment and are highly resistant to numerous antibiotics. Thus, Stenotrophomonas serves as a reservoir of genes encoding antimicrobial resistance (AMR). The detection rate of Stenotrophomonas is rapidly increasing alongside their strengthening intrinsic ability to tolerate a variety of clinical antibiotics. This review illustrated the current genomics advances of antibiotic resistant Stenotrophomonas, highlighting the importance of precise identification and sequence editing. In addition, AMR diversity and transferability have been assessed by the developed bioinformatics tools. However, the working models of AMR in Stenotrophomonas are cryptic and urgently required to be determined. Comparative genomics is envisioned to facilitate the prevention and control of AMR, as well as to gain insights into bacterial adaptability and drug development.
Stenotrophomonas/genetics* ; Drug Resistance, Bacterial/genetics* ; Anti-Bacterial Agents/pharmacology* ; Gram-Negative Bacteria ; Genomics ; Microbial Sensitivity Tests