Evaluation of virulence of Klebsiella pneumoniae using zebrafish behavior as a biological indicator.

INTRODUCTION: Klebsiella pneumoniae is one of the common pathogenic bacteria that can cause infections in hospitals and communities and can cause respiratory, urinary, and other multi-system infections. In recent years, the emergence of highly virulent and drug-resistant Klebsiella pneumoniae has greatly increased the difficulty of treatment for infection. Clinically, it is very important to accurately judge the virulence of isolated Klebsiella pneumoniae for treatment, but there is no better method to evaluate its virulence. METHODS: In this study, zebrafish were used as a model organism, and the swimming distance was used as a detection index to identify clinically isolated Klebsiella pneumoniae. In this study, we selected two different strains of Klebsiella pneumoniae, i.e., NTUH-K2044 and ATCC BAA-1705, with known high and low virulence, respectively, to infect zebrafish juveniles and evaluated their behavioral ability according to different bacterial concentrations and different developmental times. RESULTS: It was found that highly virulent Klebsiella pneumoniae caused a significant decrease in the behavioral ability of zebrafish larvae, while low-virulence Klebsiella pneumoniae had relatively little effect. CONCLUSIONS: These results indicate that it is entirely feasible to assess the virulence of Klebsiella pneumoniae based on behavioral ability.

Upregulated CXCL8 in placenta accreta spectruma regulates the migration and invasion of HTR-8/SVneo cells.

BACKGROUND: Placenta accreta spectrum (PAS) is mainly characterized by excessive invasion of the uterine muscle layer accompanied by a large number of foreign blood vessels, leading to severe bleeding during and after delivery. However, the mechanism of excessive invasion of nutrient cells in placenta accreta is currently unclear. METHODS: We performed RNA sequencing of 6 PAS patients and 4 control donors, coupled with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The mRNA and protein expression of C-X-C motif ligand 8 (CXCL8) in the placental tissue was measured by qRT‒PCR, immunohistochemical staining and Western blotting. HTR-8/SVneo human villous trophoblast Neo cells were used for in vitro investigation of cell migration and invasion as well as the expression level of CXCL8. RESULTS: A total of 1120 differentially expressed mRNAs were identified in PAS patients. Moreover, GO and KEGG analyses indicated that the differentially expressed mRNAs were most closely associated with immune system processes, biological adhesion and Wnt signaling pathway. The CXCL8 mRNA and protein levels in PAS tissue were significantly higher than those in normal placental tissue. Forced overexpression of CXCL8 significantly increased the migration and invasion of HTR-8/SVneo cells, accompanied by the upregulation of matrix metalloproteinase-2 and matrix metalloproteinase-9 and the downregulation of E-cadherin, which was reversed by knockdown of CXCL8. CONCLUSIONS: CXCL8 was highly expressed in PAS, and knockdown of CXCL8 suppressed the migration and invasion of HTR-8/SVneo cells, suggesting its potential as a diagnostic and therapeutic target for PAS.

Maternal colonization with group B Streptococcus and antibiotic resistance in China: systematic review and meta-analyses.

BACKGROUND: Maternal rectovaginal colonization with group B Streptococcus (GBS) or Streptococcus agalactiae is the most common pathway for this disease during the perinatal period. This meta-analysis aimed to summarize existing data regarding maternal colonization, serotype profiles, and antibiotic resistance in China. METHODS: Systematic literature reviews were conducted after searching 6 databases. Meta-analysis was applied to analyze colonization rate, serotype, and antimicrobial susceptibility of GBS clinical isolates in different regions of China. Summary estimates are presented using tables, funnel plots, forest plots, histograms, violin plots, and line plots. RESULTS: The dataset regarding colonization included 52 articles and 195 303 pregnant women. Our estimate for maternal GBS colonization in China was 8.1% (95% confidence interval [CI] 7.2%-8.9%). Serotypes Ia, Ib, III, and V account for 95.9% of identified isolates. Serotype III, which is frequently associated with the hypervirulent clonal complex, accounts for 46.4%. Among the maternal GBS isolates using multilocus sequence typing (MLST), ST19 (25.7%, 289/1126) and ST10 (25.1%, 283/1126) were most common, followed by ST12 (12.4%, 140/1126), ST17 (4.8%, 54/1126), and ST651 (3.7%, 42/1126). GBS was highly resistant to tetracycline (75.1% [95% CI 74.0-76.3%]) and erythromycin (65.4% [95% CI 64.5-66.3%]) and generally susceptible to penicillin, ampicillin, vancomycin, ceftriaxone, and linezolid. Resistance rates of GBS to clindamycin and levofloxacin varied greatly (1.0-99.2% and 10.3-72.9%, respectively). A summary analysis of the bacterial drug resistance reports released by the China Antimicrobial Resistance Surveillance System (CARSS) in the past 5 years showed that the drug resistance rate of GBS to erythromycin, clindamycin, and levofloxacin decreased slowly from 2018 to 2020. However, the resistance rates of GBS to all 3 antibiotics increased slightly in 2021. CONCLUSIONS: The overall colonization rate in China was much lower than the global colonization rate (17.4%). Consistent with many original and review reports in other parts of the world, GBS was highly resistant to tetracycline. However, the resistance of GBS isolates in China to erythromycin and clindamycin was greater than in other countries. This paper provides important epidemiological information, to assist with prevention and treatment of GBS colonization in these women.

Microstructural evolution and mechanical properties of WC-6CO cemented carbide prepared via SPS: incorporation of YSZ as a reinforcer.

WC-Co based alloys are widely applied cemented carbide materials due to unique and outstanding properties. In this study, a series of WC-6Co cemented carbides are quickly prepared via SPS and the effects of Zr2O3-7 wt% Y2O3(YSZ) on the properties of the as-prepared samples are also investigated. The results show that with the increase of the YSZ amount, the density, flexural strength and fracture toughness of the samples were particularly improved to a certain extent, but the Vickers hardness was slightly reduced. Combined with the evolution of microstructure and analysis of property changes, it can be speculated that the mechanism of YSZ additive promoting sintering can be attributed to the formation of solid solution and subsequent activation sintering process. Consequently, YSZ was preliminarily proved to be a potential enhancer for the WC-Co based cemented carbides.

In Situ Ternary Boride: Effects on Densification Process and Mechanical Properties of WC-Co Composite Coating.

New coatings resistant to corrosion in high-temperature molten zinc aluminum were prepared by supersonic flame spraying of various composite powders. These composite powders were prepared by mixing, granulation, and heat treatment of various proportions of Mo-B4C powder and WC and Co powder. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectroscopy (EDS), and mechanical analysis were used to study the effects of Mo-B4C on the microstructure, phase, porosity, bonding strength, and elastic modulus of the composite powder and coating. Results show that the addition of an appropriate quantity of Mo-B4C reacts with Co to form ternary borides CoMo2B2 and CoMoB. Ternary boride forms a perfect continuous interface, improving the mechanical properties and corrosion resistance property of the coating. When the amount of Mo-B4C added was 35.2%, the mechanical properties of the prepared coating reached optimal values: minimum porosity of 0.31 ± 0.15%, coating bonding strength of 77.81 ± 1.77 MPa, nanoindentation hardness of 20.12 ± 1.85 GPa, Young's modulus of 281.52 ± 30.22 GPa, and fracture toughness of 6.38 ± 0.45 MPa·m1/2.

Soft-lithography-based optical interconnection with high misalignment tolerance.

A low-cost, versatile optical coupling structure featuring a monolithic integration of a polymeric waveguide, beam ducts, and end-reflectors has been designed, prototyped, and demonstrated to be capable of sustaining high misalignment errors whilst maintaining a reasonable coupling efficiency. The soft lithography fabrication process of this interconnection design allows for significant advantages over traditional designs in terms of misalignment tolerance, manufacture cost and speed, as well as 3-D integration capability.