Catalytic Oxidation of Toluene over Pt/CeO2 Catalysts: A Double-Edged Sword Effect of Strong Metal-Support Interaction.

Strong metal-support interaction (SMSI), which has drawn widespread attention in heterogeneous catalysis, is thought to significantly affect the catalytic performance for volatile organic chemical (VOC) abatement. In the present study, strong interactions between platinum and ceria are constructed by modulating the oxygen vacancy concentration of CeO2 through a NaBH4 reduction method. For a catalyst with higher content of oxygen vacancy, more electrons would transfer from ceria to Pt, which is attributed to the stronger effect of SMSI. The obtained electron-richer Pt sites exhibit higher ability for toluene activation, contributing to better performance for toluene oxidation. On the other hand, the stronger metal-support interaction would facilitate CeOx species migrating to the Pt nanoparticle surface and forming an encapsulated structure. Smaller Pt dispersion leads to fewer sites for toluene adsorption and activation, which is to the disadvantage of the reaction. Therefore, taking the negative and positive effects together, the Pt/CeO2-0.5 catalyst has the highest catalytic performance for toluene abatement. Our study provides new insights into strong metal-support interaction on toluene oxidation and contributes to designing noble metal catalysts for VOC abatement.

High flux isothermal assays on the pathogenic features of Mycoplasma pneumoniae.

As one of the most important pathogens, M. pneumoniae is a causative agent responsible for atypical and other respiratory tract infections, even its extra-pulmonary complications. This study aims to use the high and rapid flux sequencing assays on the M. pneumoniae and further bioinformatic analysis, for the investigation of their clinical features and pathogenic characteristics. The results in this study on the clinical features and pathogenic characteristics of M. pneumoniae may further aid in the control and surveillance and better understanding of this pathogen.

Integron mediated bacterial resistance and virulence on clinical pathogens.

Integron was recognized as mobile elements responsible for the emergence and diffusion of antibiotic resistance, virulence and pathogenicity. The existence of resistant integron in pathogens may consequently lead to the increasing number of clinical failures in bacterial mediated diseases, as well as the expenses. In this study, a total of 22 clinical pathogens (including E. faecalis, S. aureus, K. pneumoniae, Enterobacter, P. aeruginosa and Acinetobacter) were subjected to the identification of class 1-class 3 integrons and drug resistant gene cassettes by high flux LAMP method. According to the results, the clinical isolates were screened as carrying class 1 integron with dfrA12-orfF-aadA2 cassette array, class 1 integron with dfrA17-aadA5 cassette array, class 1 integron with aadA2 cassette, class 1 integron with blaVIM2 cassette, class 1 and class 2 integron with dfrA1-sat1-aadA1 and dfrA12-orfF-aadA2 cassette arrays simultaneously, which was accordantly with the previous data. The optimized high flux LAMP assay was proceeded in water bath at 65 °C for 60 min and determined by naked eye, with the time consumption restricted within 2.5 h. Prior to conventional PCR method, the high flux LAMP assay was demonstrated as a highly-specific and highly-sensitive method. This study offered a valid LAMP method in resistance integrons detection for laboratory use, which was time-saving and easy-determination.

Microbial infection pattern, pathogenic features and resistance mechanism of carbapenem-resistant Gram negative bacilli during long-term hospitalization.

BACKGROUND: Carbapenem-resistant Gram-negative bacilli (GNB) have become an important cause of nosocomial infections of hospitalized patients. METHODS: To investigate the microbial infection patterns and molecular epidemiology characteristics of the carbapenem-resistant GNB isolates from a long-term hospitalized patient, antimicrobial susceptibility testing, phenotypic screening test for carbapenemase production, PCR screening and DNA sequencing of carbapenemase genes, repetitive extragenic palindromic sequence-based PCR (REP-PCR), multilocus sequencing typing (MLST) and genetic environment analysis were performed. RESULTS: Twelve strains with carbapenemase genes were detected from 63 carbapenem-resistant isolates, including two blaIMP-25-carrying Pseudomonas aeruginosa, one blaNDM-1-carrying Citrobacter freundii, three blaNDM-1-carrying Klebsiella pneumoniae and six blaKPC-2-carrying K. pneumoniae. Only the blaNDM-1 genes were successfully transferred from three K. pneumoniae strains to Escherichia coli C600 by conjugation. Genetic environment of blaIMP-25, blaNDM-1 and blaKPC-2 genes in our study were consistent with previous reports. Molecular typing of K. pneumoniae performed by MLST revealed that most of the isolates belonged to ST11. blaNDM-1-carrying K. pneumoniae sequencing type 1416 was first reported in our study. CONCLUSIONS: Carbapenem-resistant GNB are common pathogens during long-term hospitalization, and ST11 blaKPC-2-carrying K. pneumoniae is the dominant bacterium in our study. Colonization and horizontal transmission of resistance by plasmids of carbapenem-resistant GNB have increased the risks of persistent infection and mortality of long-term hospitalized patients.

Microbial virulence, molecular epidemiology and pathogenic factors of fluoroquinolone-resistant Haemophilus influenzae infections in Guangzhou, China.

BACKGROUND: Fluoroquinolone-resistant Haemophilus influenzae (FRHI) has been reported worldwide but remain unclear in China. METHODS: A total of 402 H. influenzae isolates collected from 2016 to 2017 were included. Antimicrobial susceptibility on 10 antibiotics was performed, and minimum inhibitory concentration of ciprofloxacin- and nalidixic acid-resistant strains were further determined by E-test strips, with risk factors also evaluated. Strains with resistance or reduced susceptibility to ciprofloxacin were subjected to sequencing of the quinolone resistance-determining regions (QRDR) and plasmid-mediated quinolone resistance genes by sequencing, with multi-locus sequence typing. RESULTS: 2.2% of H. influenzae strains were non-susceptible (7/402, 1.7%) or susceptible (2/402, 0.5%) to ciprofloxacin but NAL-resistant by E-test, and multidrug resistance was more common in fluoroquinolones non-susceptible H. influenzae group (p = 0.000). Infection risk factors included invasive procedure (p = 0.011), catching cold/previous contact with someone who had a cold (p = 0.019), fluoroquinolones use during previous 3 months (p = 0.003). With none of mutations obtained in gyrB, parE and other plasmid-mediated quinolone resistance genes, 7 and 4 strains were found for Ser-84-Leu substitutions in gyrA and one amino acid substitution in the QRDR of gyrA linked with one amino acid substitution in the QRDR of parC, respectively. In addition, five sequence types (ST) were identified, with ST1719 firstly found. CONCLUSIONS: For the first time, this study has reported the incidence, risk factors, molecular determinants on fluoroquinolones resistance and ST of FRHI strains in mainland China, representing the first evidence of mutation of gyrA and parC in China and the new ST1719 worldwide.

A Pseudo-Surfactant Chemical Permeation Enhancer to Treat Otitis Media via Sustained Transtympanic Delivery of Antibiotics.

Chemical permeation enhancers (CPEs) represent a prevalent and safe strategy to enable noninvasive drug delivery across skin-like biological barriers such as the tympanic membrane (TM). While most existing CPEs interact strongly with the lipid bilayers in the stratum corneum to create defects as diffusion paths, their interactions with the delivery system, such as polymers forming a hydrogel, can compromise gelation, formulation stability, and drug diffusion. To overcome this challenge, differing interactions between CPEs and the hydrogel system are explored, especially those with sodium dodecyl sulfate (SDS), an ionic surfactant and a common CPE, and those with methyl laurate (ML), a nonionic counterpart with a similar length alkyl chain. Notably, the use of ML effectively decouples permeation enhancement from gelation, enabling sustained delivery across TMs to treat acute otitis media (AOM), which is not possible with the use of SDS. Ciprofloxacin and ML are shown to form a pseudo-surfactant that significantly boosts transtympanic permeation. The middle ear ciprofloxacin concentration is increased by 70-fold in vivo in a chinchilla AOM model, yielding superior efficacy and biocompatibility than the previous highest-performing formulation. Beyond improved efficacy and biocompatibility, this single-CPE formulation significantly accelerates its progression toward clinical deployment.

Molecular Epidemiology and Antibiotic Resistance Analysis of Non-Typeable Haemophilus influenzae (NTHi) in Guangzhou: A Representative City of Southern China.

This study aimed to investigate the molecular epidemiology and antibiotic resistance of Haemophilus influenzae in Guangzhou, China. A total of 80 H. influenzae isolates were collected from the First Affiliated Hospital of Guangzhou Medical University from January 2020 to April 2021. Species identification, antimicrobial susceptibility, molecular capsular typing, multilocus sequence typing and the clinical characteristics analysis of patients were performed. For all recruited isolates, the majority of H. influenzae strains from patients with respiratory symptoms were found to be non-typeable H. influenzae (NTHi). The isolates were relative susceptible to third- and fourth-generation cephalosporins, quinolones and chloramphenicol, despite having a high ampicillin resistance rate (>70%). The genotyping results reveal a total of 36 sequence types (STs), with ST12 being the most prevalent ST. Remarkably, the 36 STs identified from 80 NTHi isolates within a short period of 15 months and in a single medical setting have revealed a high genetic diversity in NTHi isolates. In comparison, it is noteworthy that the most prevalent STs found in the present study have rarely been found to overlap with those from previous studies. This is the first study on the molecular epidemiology of NTHi isolates in Guangzhou, a city that is representative of southern China.

Genome-Wide Association Analysis Reveals Genetic Loci and Candidate Genes for Chest, Abdominal, and Waist Circumferences in Two Duroc Pig Populations.

Chest circumference (CC), abdominal circumference (AC), and waist circumference (WC) are regarded as important indicators for improving economic traits because they can reflect the growth and physiological status in pigs. However, the genetic architecture of CC, AC, and WC is still elusive. Here, we performed single-trait and multi-trait genome-wide association studies (GWASs) for CC, AC, and WC in 2,206 American origin Duroc (AOD) and 2,082 Canadian origin Duroc (COD) pigs. As a result, one novel quantitative trait locus (QTL) on Sus scrofa chromosome (SSC) one was associated with CC and AC in COD pigs, which spans 6.92 Mb (from 170.06 to 176.98 Mb). Moreover, multi-trait GWAS identified 21 significant SNPs associated with the three conformation traits, indicating the multi-trait GWAS is a powerful statistical approach that uncovers pleiotropic locus. Finally, the three candidate genes (ITGA11, TLE3, and GALC) were selected that may play a role in the conformation traits. Further bioinformatics analysis indicated that the candidate genes for the three conformation traits mainly participated in sphingolipid metabolism and lysosome pathways. For all we know, this study was the first GWAS for WC in pigs. In general, our findings further reveal the genetic architecture of CC, AC, and WC, which may offer a useful reference for improving the conformation traits in pigs.

Molecular epidemiology and evolution of Haemophilus influenzae.

Haemophilus influenzae remains a common cause of illness in children worldwide. H. influenzae type b is the leading cause of bacterial meningitis in children before introduction of vaccination and is a common cause of pneumonia, epiglottis and septic arthritis. Since the implementation of the Hib conjugate vaccine, the non-typeable H. influenzae has rapidly decreased in respiratory and invasive infections in children and adults. However, the rate of antibiotic resistance of H. influenzae varies with region and period and is usually on the rise. In this review, typing of H. influenzae, virulence factors and resistance will be dissertated.

Stress2TF: a manually curated database of TF regulation in plant response to stress.

Considerable studies demonstrate that plant transcription factors (TFs) play key regulatory roles in abiotic/biotic stress conditions, such as drought and pathogen attack. However, there is no effort dedicated to curate experimentally validated stress-TF regulatory relationships from these individual reports into a central database, which put an obstacle in the exploration of stress-TF regulations in plants. To address this issue, we presented a literature-curated database 'Stress2TF' that currently documented 1533 regulatory relationships between 71 abiotic/biotic stresses and 558 TFs in 47 plant species. Each entry in Stress2TF contains detailed information about a stress-TF relationship such as plant name, stress name, TF and brief description of stress-TF relationship. Stress2TF provided a user-friendly interface for entry browse, search and download. In addition, a submission page and several useful tools (e.g., BLAST, network visualization) were integrated. Stress2TF may be a valuable resource for the research of stress-TF regulatory mechanisms in plants. Stress2TF is available at http://csgenomics.ahau.edu.cn/Stress2TF.

High-spin states and level structure in stable nucleus strontium-84.

High-spin states of (84)Sr are populated through the reaction (70)Zn ((18)O, 4n) (84)Sr at the beam energy of 75 MeV. The measurements of excitation functions, γ-γ coincidences, directional correlations of oriented states (DCO) ratios and γ-transition intensities are performed using eight anticompton HPGe detectors and one planar HPGe detector. Based on the experimental results, we establish a new level scheme of (84)Sr, in which 12 new states and nearly 30 new γ-transitions are identified in the present work. The positive-parity yrast band is extended to spin I(π) = 24(+), while one negative-parity band is extended to spin I(π) = 19(-) and it is found that the even-spin and odd-spin members in high-spin states show the nature of signature staggering. The deformation of (84)Sr is studied by calculating the total-Routhian-surfaces (TRS) of positive-parity yrast states in the cranked shell model formalism.