Adaptive attenuation of virulence in hypervirulent carbapenem-resistant Klebsiella pneumoniae.

The emergence of nosocomial infections caused by hypervirulent and carbapenem-resistant K. pneumoniae (hv-CRKP) has become a significant public health challenge. The genetic traits of virulence and resistance plasmids in hv-CRKP have been extensively studied; however, research on the adaptive evolution strategies of clinical strains inside the host was scarce. This study aimed to understand the effects of antibiotic treatment on the phenotype and genotype characteristics of hv-CRKP. We investigated the evolution of hv-CRKP strains isolated from the same patient to elucidate the transition between hospital invasion and colonization. A comparative genomics analysis was performed to identify single nucleotide polymorphisms in the rmpA promoter. Subsequent validation through RNA-seq and gene deletion confirmed that distinct rmpA promoter sequences exert control over the mucoid phenotype. Additionally, biofilm experiments, cell adhesion assays, and animal infection models were conducted to illuminate the influence of rmpA promoter diversity on virulence changes. We demonstrated that the P12T and P11T promoters of rmpA possess strong activity, which leads to the evolution of CRKP into infectious and virulent strains. Meanwhile, the specific sequence of polyT motifs in the rmpA promoter led to a decrease in the lethality of hv-CRKP and enhanced cell adhesion and colonization. To summarize, the rmpA promoter of hv-CRKP is utilized to control capsule production, thereby modifying pathogenicity to better suit the host's ecological environment.IMPORTANCEThe prevalence of hospital-acquired illness caused by hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP) is significant, leading to prolonged antibiotic treatment. However, there are few reports on the phenotypic changes of hv-CRKP in patients undergoing antibiotic treatment. We performed a comprehensive examination of the genetic evolutionary traits of hv-CRKP obtained from the same patient and observed variations in the promoter sequences of the virulence factor rmpA. The strong activity of the promoter sequences P11T and P12T enhances the consistent production of capsule polysaccharides, resulting in an invasive strain. Conversely, weak promoter activity of P9T and P10T is advantageous for exposing pili, hence improving bacterial cell attachment ability and facilitating bacterial colonization. This finding also explains the confusion of some clinical strains carrying wild-type rmpA but exhibiting a low mucoid phenotype. This adaptive alteration facilitates the dissemination of K. pneumoniae within the hospital setting.

Analysis of spike and accessory 3c genes mutations of less virulent and FIP-associated feline coronaviruses in Beijing, China.

Mutations in S and 3c genes of feline coronavirus (FCoV) have been associated with the development of feline infectious peritonitis (FIP). In the present study, FCoV S and 3c genes mutations were analyzed in healthy and FIP cats. M1058L mutation was found in 13.64% (3/22) feces from FIP cats, but not in feces from healthy cats (0/39). The intact 3c gene was found in feces from both healthy cats (19/19) and FIP cats (12/12). All parenteral samples from FIP cats carried one or more of the M1058L mutation, S1060A mutation and mutated 3c gene. FCoV reverse-transcriptase polymerase chain reaction (RT-PCR) of parenteral samples (including ascites, pleural effusions and tissue) is recommended as the gold standard for clinical diagnosis of FIP rather than detection of the M1058L mutation, but when cats have severe gastrointestinal symptoms and lesions, detection of the M1058L mutation in feces may be helpful in diagnosing FIP.

Selective Separation of Chalcopyrite from Pyrite Using Sodium Humate: Flotation Behavior and Adsorption Mechanism.

Flotation separation of chalcopyrite from pyrite using lime or cyanides as depressants results in serious problems, such as the blockage of pipelines and environmental pollution. Eco-friendly organics are a future trend for beneficiation plants. In this research, the eco-friendly organic depressant sodium humate (SH) was chosen as a depressant to separate chalcopyrite from pyrite by flotation. The results indicated that SH could selectively depress pyrite owing to the oxidation species (FeOOH, Fe2(SO4)3) on its surface. The oxidation species were the adsorption sites for the COO- in the SH structure and impeded the subsequent collector potassium ethyl xanthate (KEX) adsorption. However, chalcopyrite was slightly oxidized with fewer oxidation species for SH adsorption, and KEX could be adsorbed and functioned effectively. This research suggested that SH could be an effective and eco-friendly depressant in chalcopyrite-pyrite flotation separation, which had potential use in the industry.

Four-Arm Polymer-Guided Formation of Curcumin-Loaded Flower-Like Porous Microspheres as Injectable Cell Carriers for Diabetic Wound Healing.

Stem cell injection is an effective approach for treating diabetic wounds; however, shear stress during injections can negatively affect their stemness and cell growth. Cell-laden porous microspheres can provide shelter for bone mesenchymal stem cells (BMSC). Herein, curcumin-loaded flower-like porous microspheres (CFPM) are designed by combining phase inversion emulsification with thermally induced phase separation-guided four-arm poly (l-lactic acid) (B-PLLA). Notably, the CFPM shows a well-defined surface topography and inner structure, ensuring a high surface area to enable the incorporation and delivery of a large amount of -BMSC and curcumin. The BMSC-carrying CFPM (BMSC@CFPM) maintains the proliferation, retention, and stemness of -BMSCs, which, in combination with their sustainable curcumin release, facilitates the endogenous production of growth/proangiogenic factors and offers a local anti-inflammatory function. An in vivo bioluminescence assay demonstrates that BMSC@CFPM can significantly increase the retention and survival of BMSC in wound sites. Accordingly, BMSC@CFPM, with no significant systemic toxicity, could significantly accelerate diabetic wound healing by promoting angiogenesis, collagen reconstruction, and M2 macrophage polarization. RNA sequencing further unveils the mechanisms by which BMSC@CFPM promotes diabetic wound healing by increasing -growth factors and enhancing angiogenesis through the JAK/STAT pathway. Overall, BMSC@CFPM represents a potential therapeutic tool for diabetic wound healing.

Carbon source shaped microbial ecology, metabolism and performance in denitrification systems.

The limited information on microbial interactions and metabolic patterns in denitrification systems, especially those fed with different carbon sources, has hindered the establishment of ecological linkages between microscale connections and macroscopic reactor performance. In this work, denitrification performance, metabolic patterns, and ecological structure were investigated in parallel well-controlled bioreactors with four representative carbon sources, i.e., methanol, glycerol, acetate, and glucose. After long-term acclimation, significant differences were observed among the four bioreactors in terms of denitrification rates, organic utilization, and heterotrophic bacterial yields. Different carbon sources induced the succession of denitrifying microbiota toward different ecological structures and exhibited distinct metabolic patterns. Methanol-fed reactors showed distinctive microbial carbon utilization pathways and a more intricate microbial interaction network, leading to significant variations in organic utilization and metabolite production compared to other carbon sources. Three keystone taxa belonging to the Verrucomicrobiota phylum, SJA-15 order and the Kineosphaera genus appeared as network hubs in the methanol, glycerol, and acetate-fed systems, playing essential roles in their ecological functions. Several highly connected species were also identified within the glucose-fed system. The close relationship between microbial metabolites, ecological structures, and system performances suggests that this complex network relationship may greatly contribute to the efficient operation of bioreactors.

Microbial mixotrophic denitrification using iron(II) as an assisted electron donor.

Mixotrophic denitrification processes have a great potential in nitrogen removal in biological wastewater treatment processes. However, so far, few studies have focused on the mixotrophic denitrification system using Fe(II) as an exclusively assisted electron donors and the underlying mechanisms in such a process remain unclear. Furthermore, the mechanisms by which microorganisms cover carbon, nitrogen, phosphorus and iron in an iron-assisted mixotrophic system remain unrevealed. In this work, we explore the feasibility of using Fe(II) as an assisted electron donor for enhancing simultaneous nitrogen and phosphorus removal via long-term reactor operation and batch tests. The results show that Fe(II) could provide electrons for efficient nitrate reduction and that biological reactions played a predominant role in these systems. In these systems Thermomonas, a strain of nitrate-reduction Fe(II)-oxidation bacterium, was enriched and accounted for a maximum abundance of 60.2%. These findings indicate a great potential of the Fe(II)-assisted mixotrophic denitrification system for practical use as an efficient simultaneous nitrogen and phosphorus removal process.

Evidence for human infection with avian influenza A(H9N2) virus via environmental transmission inside live poultry market in Xiamen, China.

H9N2 avian influenza virus (AIV) has become prevalent in the live poultry market (LPM) worldwide, and environmental transmission mode is an important way for AIVs to infect human beings in the LPM. To find evidence of human infection with the influenza A(H9N2) virus via environmental contamination, we evaluated one human isolate and three environmental isolates inside LPMs in Xiamen, China. The phylogeny, transmissibility, and pathogenicity of the four isolates were sorted out systematically. As for the H9N2 virus, which evolved alongside the "Avian-Environment-Human" spreading chain in LPMs from the summer of 2019 to the summer of 2020, its overall efficiency of contact and aerosol transmissibility improved, which might contribute to the increasing probability of human infection. This study indicated that environmental exposure might act as an important source of human infection in LPMs.

Etiologic characteristics of avian influenza H11 viruses isolated from the live poultry market in southeast coastal region in China.

Since it was first identified in 1956, the H11 subvariant influenza virus has been reported worldwide. However, due to the low pathogenicity of the H11 subvariant and the absence of its widespread transmission among humans, there are only a few reports on the etiology of the H11 subvariant influenza virus. Therefore, in the present study, we isolated a strain of the H11N3 avian influenza virus (AIV) from poultry feces from the live poultry market in the southeast coastal region of China. Considering that the H11 subvariant is known to cause infections in humans and to enrich the knowledge of the H11 subvariant of the avian influenza virus, the genetics, pathogenicity, and transmissibility of the isolate were studied. The phylogenetic analysis indicated that the H11N3 isolate was of Eurasian origin and carried genes closely related to duck H7N2 and H4N6. The receptor binding analysis revealed that the H11N3 isolate only acquired a binding affinity for avian-derived receptors. In the respiratory system of mice, the isolate could directly cause infection without adaptation. In addition, the results from transmission experiments and antibody detection in guinea pigs demonstrated that H11N3 influenza viruses can efficiently transmit through the respiratory tract in mammalian models. Direct infection of the H11N3 influenza virus without adaptation in the mouse models and aerosol transmission between guinea pig models confirms its pandemic potential in mammals, underscoring the importance of monitoring rare influenza virus subtypes in future studies.

Microstructure, Mechanical and Tribological Properties of Arc Ion Plating NbN-Based Nanocomposite Films.

NbN, NbN-Ag and NbN/NbN-Ag multilayer nanocomposite films were successfully deposited by an arc ion plating system (AIP), and their microstructures, mechanical and tribological properties were systematically investigated. The results show that all the films had a polycrystalline structure, and the Ag in the Ag-doped films existed independently as a face-centered cubic phase. The content of Ag in NbN-Ag and NbN/NbN-Ag films was 20.11 and 9.07 at.%, respectively. NbN films fabricated by AIP technique had excellent mechanical properties, and their hardness and critical load were up to 44 GPa and 34.6 N, respectively. The introduction of Ag into NbN films obviously reduced the friction coefficient at room temperature, while the mechanical properties and wear resistance were degraded sharply in comparison with that of NbN films. However, the NbN/NbN-Ag films presented better hardness, H/E*, H3/E*2, adhesive strength and wear resistance than NbN-Ag films. Additionally, analysis of wear surfaces of the studied films and Al2O3 balls using 3D images, depth profiles, energy dispersive spectrometry (EDS) and Raman spectra indicated that the main wear mechanisms of NbN and NbN/NbN-Ag films were adhesive and oxidation wear with slight abrasive wear, while the severe abrasive and oxidation wear were the dominant wear mechanism for NbN-Ag films.

Controllable preparation of bioactive open porous microspheres for tissue engineering.

Biodegradable microspheres have been widely applied as cell carriers for tissue engineering and regenerative medicine. However, most cell carriers only have a simple planar structure and show poor biological activity and cell adherence, resulting in low cell density and unfavorable application effect. How to develop size-controllable microspheres with an open-porous structure remains a challenge, and is a key factor to extend their employment as cell/drug delivery vehicles to boost regeneration of tissues (e.g., bone). Herein, well-defined open porous microspheres of poly(lactic-co-glycolic acid) (PLGA with good biocompatibility approved by the Food and Drug Administration (FDA)) were developed by using a gas-assisted-emulsion and surface-alkalization-treatment technology (GEST). The gas-assisted-emulsion strategy enables the formation of microspheres with a large size of 200-300 µm, meanwhile, the microspheres have a large amount of micropores with diameter in the range of 10-60 µm. The following alkalization-treatment on the surface makes the microspheres form a good porous interconnectivity throughout both the surface and the interior of the microspheres. The good porous interconnectivity endows the microspheres with a highly open pore structure and a large specific surface area for nutrient exchange and cell attachment, thus promoting cell proliferation and nutrient transportation, promising their potential as an ideal cell carrier to increase cell density and bioactivity for cell therapy-based tissue engineering.

Microsphere-containing Hydrogel Scaffolds for Tissue Engineering.

Key Laboratory for Ultrafine Materials of Ministry of Education Centre for Biomedical Technologies Current tissue engineering technology aims to achieve the regeneration of human tissues, which integrates the key factors such as scaffolds, cells and biomolecules. Among these key factors, the development of high-performance scaffolds is the basis for the success of tissue engineering strategies. In the past decades, hydrogel scaffolds have been developed rapidly and widely used in biomedical field, however, their drawbacks have also been revealed, which shows that a single hydrogel scaffold cannot meet the excellent performance required in the field of tissue engineering. Recently, microspheres have been further engineered to fabricate structurally and functionally reliable artificial three-dimensional scaffolds of desired shape with enhanced specific biological functions. Therefore, the effective combination of hydrogel and microspheres can facilitate the development of high-performance scaffolds for tissue engineering and further fine-tuning the composite structure, which is expected to solve the dilemma faced by a single scaffold. In this review paper, we systematically summurized the type and preparation method for synthesis of hydrogel and microsphere materials commonly used in developing microsphere-containing hydrogel scaffolds. We then reviewed the broad application of these hybrid scaffolds in various fields of tissue engineering, followed by a summary and perspective on future directions.

Non-Halogenated Solvents and Layer-by-Layer Blade-Coated Ternary Organic Solar Cells via Cascade Acceptor Adjusting Morphology and Crystallization to Reduce Energy Loss.

The power conversion efficiency (PCE) of halogenated solvent spin-coated organic solar cells (OSCs) has been boosted to a high level (>18%) by developing efficient photovoltaic materials and precise morphological control. However, the PCE of OSCs prepared from non-halogenated solvents and with a scalable printing process is far behind, limited by tough morphology manipulation. Herein, we have fabricated ternary OSCs by using layer-by-layer (LBL) blade-coating and a non-halogenated solvent. The ternary OSCs based on the PM6:IT-M(1:0.2)/BTP-eC9 active layer are processed with the hydrocarbon solvent 1,2,4-trimethylbenzene with no need of any additives and post-treatment. The vertical donor/acceptor distribution is optimized by LBL blade-coating within the PM6:IT-M(1:0.2)/BTP-eC9 active layer. The cascade acceptor IT-M blended in PM6 not only attenuates the damage of BTP-eC9 to the PM6 crystallization, leading to a dense nanofiber-like morphology, but also prefers to reside between PM6 and BTP-eC9 to form a cascade energy level alignment for a fast charge-transfer process. Finally, the improved morphology and crystallization lead to a reduced molecular recombination, low energy loss, and high open-circuit voltage. The prepared non-halogenated solvent and LBL blade-coated OSCs achieve a PCE of 17.16%. The work provides an approach to fabricate hydrocarbon solvent-processed high-performance OSCs by employing LBL blade-coating and a ternary strategy.

Dynamic insights into increasing antibiotic resistance in Staphylococcus aureus by label-free SERS using a portable Raman spectrometer.

Rapid and quantitative detection of bacterial antibiotic resistance is of great significance for the prevention and treatment of infections and understanding drug-resistant mechanism. In this study, label-free surface-enhanced Raman spectroscopy (SERS) technology was applied to dynamically explore oxacillin/cefazolin-derived resistance in Staphylococcus aureus using a portable Raman spectrometer. The results showed that S. aureus rapidly responded to oxacillin/cefazolin stimulation and gradually developed different degrees of drug resistance during the 21 days of exposure. The molecular changes that accumulated in the drug-resistant strains were sensitively recorded by SERS in a whole-cell manner. Principal components-linear discriminant analysis correctly distinguished various degrees of drug-resistant strains. The typical Raman peak intensities of I734/I867 showed a negative and non-linear correlation with the minimum inhibitory concentration (MIC). The correlation coefficient reached above 0.9. The target sites of oxacillin/cefazolin on S. aureus clearly reflected on SERS profiles. The results collected by SERS were further verified by other biological methods including the antibiotic susceptibility test, MIC determination, and PCR results. This study indicates that SERS technology provides a rapid and flexible alternative to current drug susceptibility testing, laying a foundation for qualitative and quantitative evaluation of drug resistance in clinical detection.

Visualization of the infection risk assessment of SARS-CoV-2 through aerosol and surface transmission in a negative-pressure ward.

Since December 2019, coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a great challenge to the world's public health system. Nosocomial infections have occurred frequently in medical institutions worldwide during this pandemic. Thus, there is an urgent need to construct an effective surveillance and early warning system for pathogen exposure and infection to prevent nosocomial infections in negative-pressure wards. In this study, visualization and construction of an infection risk assessment of SARS-CoV-2 through aerosol and surface transmission in a negative-pressure ward were performed to describe the distribution regularity and infection risk of SARS-CoV-2, the critical factors of infection, the air changes per hour (ACHs) and the viral variation that affect infection risk. The SARS-CoV-2 distribution data from this model were verified by field test data from the Wuhan Huoshenshan Hospital ICU ward. ACHs have a great impact on the infection risk from airborne exposure, while they have little effect on the infection risk from surface exposure. The variant strains demonstrated significantly increased viral loads and risks of infection. The level of protection for nurses and surgeons should be increased when treating patients infected with variant strains, and new disinfection methods, electrostatic adsorption and other air purification methods should be used in all human environments. The results of this study may provide a theoretical reference and technical support for reducing the occurrence of nosocomial infections.