This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

BackgroundMicroRNAs (miRNAs) are small, non-coding RNAs capable of postranscriptionally regulating gene expression. Accurate expression profiling is crucial for understanding the biological roles of miRNAs, and exploring them as biomarkers of diseases.Methodology/Principal FindingsA novel, highly sensitive, and reliable miRNA quantification approach,termed S-Poly(T) miRNA assay, is designed. In this assay, miRNAs are subjected to polyadenylation and reverse transcription with a S-Poly(T) primer that contains a universal reverse primer, a universal Taqman probe, an oligo(dT)11 sequence and six miRNA-specific bases. Individual miRNAs are then amplified by a specific forward primer and a universal reverse primer, and the PCR products are detected by a universal Taqman probe. The S-Poly(T) assay showed a minimum of 4-fold increase in sensitivity as compared with the stem-loop or poly(A)-based methods. A remarkable specificity in discriminating among miRNAs with high sequence similarity was also obtained with this approach. Using this method, we profiled miRNAs in human pulmonary arterial smooth muscle cells (HPASMC) and identified 9 differentially expressed miRNAs associated with hypoxia treatment. Due to its outstanding sensitivity, the number of circulating miRNAs from normal human serum was significantly expanded from 368 to 518.Conclusions/SignificanceWith excellent sensitivity, specificity, and high-throughput, the S-Poly(T) method provides a powerful tool for miRNAs quantification and identification of tissue- or disease-specific miRNA biomarkers.

It is well known that the recently developed photoinduced metal-free atom transfer radical polymerization (ATRP) has been considered as a promising methodology to completely eliminate transition metal residue in polymers. However, a serious problem needs to be improved, namely, large amount of organic photocatalysts should be used to keep the controllability over molecular weights and molecular weight distributions. In this work, a novel photocatalyst 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) with strong excited state reduction potential is successfully used to mediate a metal-free ATRP of methyl methacrylate just with parts per million (ppm) level usage under irradiation of blue light emitting diode at room temperature, using ethyl α-bromophenyl-acetate as a typical initiator with high initiator efficiency. The polymerization kinetic study, multiple controlled "on-off" light switching cycle regulation, and chain extension experiment confirm the "living"/controlled features of this promising photoinduced metal-free ATRP system with good molecular weight control in the presence of ppm level photocatalyst 4CzIPN.

Although antimicrobial resistance poses a great challenge to clinicians in China, there are limited antimicrobial resistance data on Gram-negative bacteria nationwide. We investigated the phenotypic characteristics of carbapenem-resistant Escherichia coli (CREC) and Klebsiella pneumoniae (CRKP) as well as extensively drug-resistant strains of Pseudomonas aeruginosa (XDRPA) and Acinetobacter baumannii (XDRAB) isolated from blood cultures in China. Data were collected on 24113 isolates from the China surveillance of antimicrobial resistance program in 2013, which comprised 208 hospitals located in all seven administrative regions of China. Minimum inhibitory concentrations (MICs) for common antimicrobials were determined by commercial automated systems available at local hospitals, and associations with geographic and clinical distributions was further studied. The overall prevalence of CREC, CRKP, XDRAB and XDRPA strains was 1.0, 5.5, 13.7 and 4.2%, respectively. Except for CREC, which did not differ greatly by region, the prevalence of the remaining three strains varied significantly across regions. The highest prevalence of CRKP (10.6%) and XDRAB (13.1%) were found in the pediatric group, and higher prevalence of all four target strains was found in the intensive care unit. For imipenem, 55.8% of CREC and 22.9% of CRKP strains had MICs of ≤4 μg/mL, while 97.4% XDRAB and 84% XDRPA isolates had MICs of ≥16 μg/mL. All CREC, CRKP and 81.2% of XDRAB strains were susceptible to tigecycline, with MIC90 values of 0.5, 2 and 4 μg/mL, respectively. In conclusion, a high prevalence of CRKP and XDRAB has emerged in China, especially in children and in the intensive care unit.