Uracil-DNA-glycosylase-assisted loop-mediated isothermal amplification for detection of bacteria from urine samples with reduced contamination.

Loop-mediated isothermal amplification (LAMP) is a useful molecular biology technology for analytical applications, but it is prone to contamination because of escaped aerosols, leading to false positive results. This report establishes an integrated, rapid, and accurate method to detect bacteria in urine samples by incorporating uracil-DNA-glycosylase (UDG) into real-time loop-mediated isothermal amplification (RT-LAMP). To do this, nucleic acids from five clinically important uropathogens, including Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus mirabilis, and Enterococcus faecalis, were directly captured and concentrated using Flinders Technology Associates (FTA) Elute cards. Following elution, the extracted DNAs were specifically amplified with sets of LAMP primers. The added UDG in the modified LAMP reaction excises uracils from previously amplified products or contaminants and generates apyrimidinic (AP) sites, reducing false positive rates. This UDG-assisted RT LAMP strategy was able to degrade carryover contaminants to as little as 1 femtogram (10-15 g). The assay showed a limit of detection of 104 CFU mL-1 with a sensitivity of 94.1% and a specificity of 95.0%. Both the sensitivity and specificity were improved compared to LAMP carried out without UDG. Our results indicate that the UDG-assisted RT LAMP is of great potential for rapid and precise analysis of nucleic acids in real applications.

CDK7 inhibition suppresses rheumatoid arthritis inflammation via blockage of NF-κB activation and IL-1ß/IL-6 secretion.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by joint swelling, joint tenderness and destruction of synovial joints, leading to severe disability. Anti-inflammatory drugs and disease-modifying anti-rheumatic drugs (DMARDs) may improve RA process. However, in most patients the treatment effect is still not satisfactory. Cyclin-dependent kinase 7 (CDK7) plays a well-established role in the regulation of the eukaryotic cell division cycle, and recent studies indicated that it exerted anti-inflammatory effect. In our previous research, we found that inhibition of CDK7 by highly selective inhibitor BS-181 significantly impeded the development of collagen-induced arthritis (CIA) mice. However, the underlying mechanism of CDK7 in RA remains to be explored. We elucidated the molecular mechanism of CDK7 inhibition in RA inflammation by administration of CDK7 highly selective inhibitor BS-181 and siRNA-CDK7. We found that both IL-1ß, IL-6, IL-8 and RANKL transcript levels and IL-1ß/IL-6 secretion were effectively suppressed by BS-181 treatment as well as CDK7 knockdown. Furthermore, CDK7 inhibition prevented NF-κB signalling pathway activation and restrained p65 nuclear translocation. Moreover, CDK7 selective inhibitor BS-181 also blocked phosphorylation of p65 in MH7A cells. These results strongly indicate that CDK7 inhibition by BS-181 and siRNA-CDK7 significantly suppresses rheumatoid arthritis inflammation, which may be via blockage of NF-κB signalling pathway and IL-1ß/IL-6 secretion.

Rapid and visual detection of Mycoplasma genitalium using recombinase polymerase amplification combined with lateral flow strips.

Mycoplasma genitalium (MG) is an important sexually transmitted pathogen that can cause urethritis in males and pelvic inflammatory disease in females. Due to its complex growth requirements and lengthy incubation times, culturing MG in clinical laboratories is impractical. Here we describe a rapid and visual assay combining recombinase polymerase amplification (RPA) with lateral flow (LF) strips to detect MG (MG-RPA-LF). The limit of detection (LoD) of this method was 33.6 genome equivalents (GE) per reaction, using a dilution series of purified genomic DNA. Clinical performance was evaluated by testing 100 urogenital swabs. Compared to the Simultaneous Amplification and Testing assay, our MG-RPA-LF assay showed a sensitivity of 94 % (95 % CI, 82 %-98 %) and a specificity of 100 % (95 % CI, 91 %-100 %). The overall concordance between the two methods was 97 % (95 % CI, 91 %-99 %) with a κ coefficient of 0.94 (P < 0.001). Without cumbersome and expensive instruments, this method is anticipated to be a promising alternative to diagnose MG infection, especially in resource-poor settings.