PPARδ agonist protects against osteoarthritis by activating AKT/mTOR signaling pathway-mediated autophagy.

Osteoarthritis (OA) is the most prevalent degenerative joint disease, and PPARs are involved in its pathogenesis; however, the specific mechanisms by which changes in PPARδ impact the OA pathogenesis yet to be discovered. The purpose of this study was to ascertain how PPARδ affects the onset and development of OA. In vitro, we found that PPARδ activation ameliorated apoptosis and extracellular matrix (ECM) degradation in OA chondrocytes stimulated by IL-1ß. In addition, PPARδ activation may modulate AKT/mTOR signaling to partially regulate chondrocyte autophagy and apoptosis. In vivo, injection of PPARδ agonist into the articular cavity improved ECM degradation, apoptosis and autophagy in rats OA models generated by destabilization medial meniscus (DMM), eventually delayed degeneration of articular cartilage. Thus, targeting PPARδ for OA treatment may be a possibility.

Graphdiyne/metal oxide hybrid materials for efficient energy and environmental catalysis.

Graphdiyne (GDY)-based materials, owing to their unique structure and tunable electronic properties, exhibit great potential in the fields of catalysis, energy, environmental science, and beyond. In particular, GDY/metal oxide hybrid materials (GDY/MOs) have attracted extensive attention in energy and environmental catalysis. The interaction between GDY and metal oxides can increase the number of intrinsic active sites, facilitate charge transfer, and regulate the adsorption and desorption of intermediate species. In this review, we summarize the structure, synthesis, advanced characterization, small molecule activation mechanism and applications of GDY/MOs in energy conversion and environmental remediation. The intrinsic structure-activity relationship and corresponding reaction mechanism are highlighted. In particular, the activation mechanisms of reactant molecules (H2O, O2, N2, etc.) on GDY/MOs are systemically discussed. Finally, we outline some new perspectives of opportunities and challenges in developing GDY/MOs for efficient energy and environmental catalysis.

Fluid shear force and hydrostatic pressure jointly promote osteogenic differentiation of BMSCs by activating YAP1 and NFAT2.

Natural bone tissue features a complex mechanical environment, with cells responding to diverse mechanical stimuli, including fluid shear stress (FSS) and hydrostatic pressure (HP). However, current in vitro experiments commonly employ a singular mechanical stimulus to simulate the mechanical environment in vivo. The understanding of the combined effects and mechanisms of multiple mechanical stimuli remains limited. Hence, this study constructed a mechanical stimulation device capable of simultaneously applying FSS and HP to cells. This study investigated the impact of FSS and HP on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and examined the distinctions and interactions between the two mechanisms. The results demonstrated that both FSS and HP individually enhanced the osteogenic differentiation of BMSCs, with a more pronounced effect observed through their combined application. BMSCs responded to external FSS and HP stimulation through the integrin-cytoskeleton and Piezo1 ion channel respectively. This led to the activation of downstream biochemical signals, resulting in the dephosphorylation and nuclear translocation of the intracellular transcription factors Yes Associated Protein 1 (YAP1) and nuclear factor of activated T cells 2 (NFAT2). Activated YAP1 could bind to NFAT2 to enhance transcriptional activity, thereby promoting osteogenic differentiation of BMSCs more effectively. This study highlights the significance of composite mechanical stimulation in BMSCs' osteogenic differentiation, offering guidance for establishing a complex mechanical environment for in vitro functional bone tissue construction.

Composition and evolutionary characterization of the gut microbiota in pigs.

The intestinal microbiota plays significant role in the physiology and functioning of host organisms. However, there is limited knowledge of the composition and evolution of microbiota-host relationships from wild ancestors to modern domesticated species. In this study, the 16S rRNA gene V3-V4 in the intestinal contents of different pig breeds was analyzed and was compared using high-throughput sequencing. This identified 18 323 amplicon sequence variants, of which the Firmicutes and Actinobacteria phyla and Bifidobacterium and Allobaculum genera were most prevalent in wild pigs (WP). In contrast, Proteobacteria and Firmicutes predominated in Chinese Shanxi Black pigs (CSB), while Firmicutes were the most prevalent phylum in Large White pigs (LW) and Iberian pigs (IB), followed by Bacteroidetes in IB and Proteobacteria in LW. At the genus level, Shigella and Lactobacillus were most prevalent in CSB and LW, while Actinobacillus and Sarcina predominated in IB. Differential gene expression together with phylogenetic and functional analyses indicated significant differences in the relative abundance of microbial taxa between different pig breeds. Although many microbial taxa were common to both wild and domestic pigs, significant diversification was observed in bacterial genes that potentially influence host phenotypic traits. Overall, these findings suggested that both the composition and functions of the microbiota were closely associated with domestication and the evolutionary changes in the host. The members of the microbial communities were vertically transmitted in pigs, with evidence of co-evolution of both the hosts and their intestinal microbial communities. These results enhance our understanding and appreciation of the complex interactions between intestinal microbes and hosts and highlight the importance of applying this knowledge in agricultural and microbiological research.

A novel laboratory-based nomogram for assessing infection presence risk in acute-on-chronic liver failure patients.

Accurate assessment of infection presence risk level, timely diagnosis, and effective control are critical for decreasing mortality of Acute­on­chronic liver failure (ACLF). We aimed to develop and validate a novel diagnostic model to accurately assess infection presence risk level in ACLF patients. 185 ACLF patients with/without infection were enrolled, and their demographic, physical findings, immune-inflammatory, hepatic function, metabolism, and coagulation-fibrinolysis indicators were analyzed. Regression analysis was performed to identify the independent diagnostic parameters, which were further used to establish diagnostic models with a nomogram for visual. An area under receiver operating characteristic curve (AUROC), calibration plots, clinical impact curves, decision curve analysis, and net reclassification index were used to evaluate and identify the best model. An external validating cohort was introduced to verify the diagnostic accuracy. We screened out white blood cell (WBC) count, LYM%, blood urea nitrogen (BUN), and D-dimer for assessing infection presence risk levels in ACLF patients. WBD (WBC + BUN + D-dimer) was established and proposed as a novel diagnostic model for infection presence risk levels assessment in ACLF patients with an AUROC of 0.803 (95%CI 0.723-0.883), 0.885 (95%CI 0.786-0.984) in training and external cohorts, respectively. In stratification analysis by ACLF etiology and stages, WBD achieved an AUROC of 0.791 (95%CI 0.691-0.891) and 0.873 (95%CI 0.78-0.966) in HBV-related and early-stage patients, respectively. Whereas a higher AUROC of 0.905 (95%CI 0.807-1.00) in the early-stage of HBV-related ACLF patients indicated its optimum application scope. WBD, a novel laboratory-based nomogram, can serve as a decision-making support tool for clinicians to assess infection presence risk levels in ACLF patients.

Targeting LGSN restores sensitivity to chemotherapy in gastric cancer stem cells by triggering pyroptosis.

Gastric cancer (GC) is notoriously resistant to current therapies due to tumor heterogeneity. Cancer stem cells (CSCs) possess infinite self-renewal potential and contribute to the inherent heterogeneity of GC. Despite its crucial role in chemoresistance, the mechanism of stemness maintenance of gastric cancer stem cells (GCSCs) remains largely unknown. Here, we present evidence that lengsin, lens protein with glutamine synthetase domain (LGSN), a vital cell fate determinant, is overexpressed in GCSCs and is highly correlated with malignant progression and poor survival in GC patients. Ectopic overexpression of LGSN in GCSC-derived differentiated cells facilitated their dedifferentiation and treatment resistance by interacting with vimentin and inducing an epithelial-to-mesenchymal transition. Notably, genetic interference of LGSN effectively suppressed tumor formation by inhibiting GCSC stemness maintenance and provoking gasdermin-D-mediated pyroptosis through vimentin degradation/NLRP3 signaling. Depletion of LGSN combined with the chemo-drugs 5-fluorouracil and oxaliplatin could offer a unique and promising approach to synergistically rendering this deadly cancer eradicable in vivo. Our data place focus on the role of LGSN in GCSC regeneration and emphasize the critical importance of pyroptosis in battling GCSC.

Cronobacter spp. Isolated from Quick-Frozen Foods in China: Incidence, Genetic Characteristics, and Antibiotic Resistance.

Cronobacter spp. are emerging foodborne pathogens that cause severe diseases. However, information on Cronobacter contamination in quick-frozen foods in China is limited. Therefore, we studied the prevalence, molecular characterization, and antimicrobial susceptibility of Cronobacter in 576 quick-frozen food samples collected from 39 cities in China. Cronobacter spp. were found in 18.75% (108/576) of the samples, and the contamination degree of the total positive samples was 5.82 MPN/g. The contamination level of frozen flour product samples was high (44.34%). Among 154 isolates, 109 were C. sakazakii, and the main serotype was C. sakazakii O1 (44/154). Additionally, 11 serotypes existed among four species. Eighty-five sequence types (STs), including 22 novel ones, were assigned, indicating a relatively high genetic diversity of the Cronobacter in this food type. Pathogenic ST148, ST7, and ST1 were the main STs in this study. ST4, epidemiologically related to neonatal meningitis, was also identified. All strains were sensitive to cefepime, tobramycin, ciprofloxacin, and imipenem, in which the resistance to cephalothin was the highest (64.94%).Two isolates exhibited multidrug resistance to five and seven antimicrobial agents, respectively. In conclusion, these findings suggest that the comparatively high contamination level of Cronobacter spp. in quick-frozen foods is a potential risk warranting public attention.

Osteosarocma progression in biomimetic matrix with different stiffness: Insights from a three-dimensional printed gelatin methacrylamide hydrogel.

Recent studies on osteosarcoma and matrix stiffness are still mostly performed in a 2D setting, which is distinct from in vivo conditions. Therefore, the results from the 2D models may not reflect the real effect of matrix stiffness on cell phenotype. Here, we employed a 3D bioprinted osteosarcoma model, to study the effect of matrix stiffness on osteosarcoma cells. Through density adjustment of GelMA, we constructed three osteosarcoma models with distinct matrix stiffnesses of 50, 80, and 130 kPa. In this study, we found that osteosarcoma cells proliferated faster, migrated more actively, had a more stretched morphology, and a lower drug sensitivity in a softer 3D matrix. When placed in a stiffer matrix, osteosarcoma cells secrete more MMP and VEGF, potentially to fight for survival and attract vascular invasion. Transcriptomic analysis showed that matrix stiffness could impact the signaling pathway of integrin α5-MAPK. The transplantation of 3D printed models in nude mice showed that cells encapsulated in the softer hydrogel were more likely to form subcutaneous tumors. These results suggest that matrix stiffness plays an important role in the development of osteosarcoma in a 3D environment and that inhibition of integrin α5 could block the signal transduction of matrix stiffness.

Effect of PI3K/AKT/mTOR signaling pathway-based clustered nursing care combined with papaverine injection on vascular inflammation and vascular crisis after replantation of severed fingers.

This research aimed to investigate the effect of PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B)/mTOR (mammalian target protein of rapamycin) signaling pathway-based clustering care combined with papaverine injection on vascular inflammation and vascular crisis after finger amputation and replantation. 100 patients admitted in General Hospital of Ningxia Medical University from April 2022 to December 2022 for replantation of severed fingers were selected and divided into a control group (n = 50) and an observation group (n = 50) using the randomized grouping principle. The control group received a papaverine injection and general nursing care, the observation group received a papaverine injection and clustered care. The pain score; constipation incidence; replantation finger survival rate; physician, nurse, and patient satisfaction; serum inflammatory factors; vascular crisis parameters; and occurrence of adverse reactions were compared between the two patient groups. Enzyme-linked immunosorbent assay was performed to detect PI3K, AKT, and mTOR protein concentrations in the venous blood of the two groups, and statistical analysis of the data was performed. On postoperative day 7, the pain score and incidence of constipation in the observation group were lower than those in the control group (P < 0.05); the survival rate of reimplanted fingers in the observation group was 88.00%, which was higher than that in the control group 80.00% (P < 0.05); the satisfaction of doctors, nurses, and patients in the observation group was higher than that in the control group; the concentrations of interleukin-1 (IL-1), tumor necrosis factor (TNF-α), blood flow resistance index (RI), and arterial pulsatility index (PI) in the observation group were lower than those in the control group, while the concentration of interleukin-10 (IL-10), vascular diameter, and Vm (mean blood flow velocity) were higher in the observation group than those in the control group; the differences were statistically significant (P < 0.05). The difference in the incidence of adverse reactions between the two groups was not statistically significant (P > 0.05). The concentrations of PI3K, AKT, and mTOR proteins in the observation group were higher than those in the control group (P < 0.05). The concentrations of PI3K, AKT, and mTOR proteins in the observation group were higher than those in the control group (P < 0.05). Overall, these findings suggest that clustered care combined with papaverine injection reduces vascular inflammatory symptoms and vascular crisis in the treatment of severed finger replantation through the PI3K/AKT/mTOR signaling pathway.

Rapid Ozone Decomposition over Water-activated Monolithic MoO3 /Graphdiyne Nanowalls under High Humidity.

Catalytic ozone (O3 ) decomposition at high relative humidity (RH) remains a great challenge due to the catalysts poison and deactivation under high humidity. Here, we firstly elaborate the role of water activation and the corresponding mechanism of the promoted O3 decomposition over the three-dimensional monolithic molybdenum oxide/graphdiyne (MoO3 /GDY) catalyst. The O3 decomposition over MoO3 /GDY reaches up to 100 % under high humid condition (75 % RH) at room temperature, which is 4.0 times as high as that of dry conditions, significantly surpasses other carbon-based MoO3 materials(≤7.1 %). The sp-hybridized carbon in GDY donates electrons to MoO3 along the C-O-Mo bond, facilitating water activation to form hydroxyl species. As a result, hydroxyl species dissociated from water act as new active sites, promoting the adsorption of O3 and the generation of new intermediate species (hydroxyl ⋅OH and superoxo ⋅O2 - ), which significantly lowers the energy barriers of O3 decomposition (0.57 eV lower than dry conditions).

Research Progresses on the Function and Detection Methods of Insect Gut Microbes.

The insect gut is home to an extensive array of microbes that play a crucial role in the digestion and absorption of nutrients, as well as in the protection against pathogenic microorganisms. The variety of these gut microbes is impacted by factors such as age, diet, pesticides, antibiotics, sex, and caste. Increasing evidence indicates that disturbances in the gut microbiota can lead to compromised insect health, and that its diversity has a far-reaching impact on the host's health. In recent years, the use of molecular biology techniques to conduct rapid, qualitative, and quantitative research on the host intestinal microbial diversity has become a major focus, thanks to the advancement of metagenomics and bioinformatics technologies. This paper reviews the main functions, influencing factors, and detection methods of insect gut microbes, in order to provide a reference and theoretical basis for better research utilization of gut microbes and management of harmful insects.

Genome Characterization of the Novel Lytic Enterobacter cloacae Phage vB_EclM_Q7622.

Enterobacter cloacae is a widespread opportunistic pathogen that causes urinary tract infection. The abuse of antibiotics enabled multidrug-resistant strains to spread. Bacteriophage therapy is a naturally, safe, and efficient alternative treatment technology against multi-resistant bacteria. In this study, a virulent phage vB_EclM_Q7622 (Q7622) was isolated from the sewage of Jiangcun poultry market in Guangzhou city. Transmission electron microscopy indicated that Q7622 had an icosahedral head (97.8 ± 5.6 nm in diameter) and a short, contractile tail (113.7 ± 4.5 nm). Its double-stranded DNA genome is composed of 173,871 bp with a GC content of 40.02%. It possesses 297 open reading frames and 9 tRNAs. No known virulence and resistance genes were detected, indicated that phage Q7622 could be used for pathogens prevention and control safely. Comparative genomic and phylogenetic analysis showed that Q7622 was highly similar to the phages vB_EclM_CIP9 and vB_EhoM-IME523. The highest nucleotide similarity between Q7622 and the similar phages in NCBI calculated by pyANI and VIRIDIC were 94.9% and 89.1% with vB_EhoM-IME523 respectively, below 95%. Thus, according to the result of nucleotide similarity calculation results, Q7622 was a novel virulent Enterobacter cloacae phage strain of the genus Kanagawavirus.

Phosphine-based metal-organic layers to construct single-site heterogeneous catalysts for arene borylation.

Metal-organic layers (MOLs) are versatile platforms for creating single-site heterogeneous catalysts. Incorporating molecular functionalities into MOLs is crucial for catalysis. In this study, we synthesized phosphine-containing MOLs constructed from Hf6-oxo secondary building units (SBUs) and phosphine ligands. The mono(phosphine)-Ir complexes generated by the metalation of TPP-MOL were highly active as heterogeneous catalysts for the C(sp2)-H borylation of a range of arenes. This research expands the diversity of MOL-based catalysts.

[Clinical characteristics of nasal respiratory epithelial adenomatoid hamartoma].

〓 Objectives: To analyze the pathological and clinical features of nasal respiratory epithelial adenomatoid hamartoma（REAH）, and summarize the diagnostic points, to improve the experience of diagnosis and treatment. Methods:The clinical data of 16 patients with REAH were analyzed retrospectively. The clinical manifestations, pathological features, imaging features, surgical treatment and prognosis were summarized. Results:16 cases of REAH were studied, 10 cases（62.50%） were associated with sinusitis, 1 case（6.25%） was associated with inverted papilloma, 1 case（6.25%） was associated with hemangioma. 5 cases（31.25%） had a history of nasal sinus surgery, including 1 case with 3 times of nasal sinus surgery, 1 case with 2 times of nasal sinus surgery, 3 cases with 1 time of nasal sinus surgery; 10 cases（62.50%） occurred in the bilateral olfactory cleft, 2 cases（12.50%） in the unilateral olfactory cleft, 3 cases（18.75%） in the unilateral middle turbinate, 1 case（6.25%） in the nasopharynx. All 16 patients were pathologically diagnosed as REAH. In the patients with lesions located in bilateral olfactory fissures, symmetrical widening of olfactory fissures and lateral displacement of middle turbinate were observed on preoperative sinus CT. The average width of bilateral olfactory fissures was （9.9±2.70） mm. The ratio of wide to narrow olfactory cleft was 1.21 ± 0.19. There was no significant difference in Lund-Mackay score between the two sides（P>0.05）. All patients underwent surgery under general anesthesia and nasal endoscopy. The follow-up period ranged from 1 to 66 months, and no recurrence occurred. Conclusion:Preoperative diagnosis of REAH is facilitated by the combination of clinical manifestations and endoscopic and imaging features. Endoscopic complete resection can achieve a good therapeutic effect.

Buckley-James boosting model based on extreme learning machine and random survival forests.

Buckley-James (BJ) model is a typical semiparametric accelerated failure time model, which is closely related to the ordinary least squares method and easy to be constructed. However, traditional BJ model built on linearity assumption only captures simple linear relationships, while it has difficulty in processing nonlinear problems. To overcome this difficulty, in this paper, we develop a novel regression model for right-censored survival data within the learning framework of BJ model, basing on random survival forests (RSF), extreme learning machine (ELM), and L2 boosting algorithm. The proposed method, referred to as ELM-based BJ boosting model, employs RSF for covariates imputation first, then develops a new ensemble of ELMs-ELM-based boosting algorithm for regression by ensemble scheme of L2 boosting, and finally, uses the output function of the proposed ELM-based boosting model to replace the linear combination of covariates in BJ model. Due to fitting the logarithm of survival time with covariates by the nonparametric ELM-based boosting method instead of the least square method, the ELM-based BJ boosting model can capture both linear covariate effects and nonlinear covariate effects. In both simulation studies and real data applications, in terms of concordance index and integrated Brier sore, the proposed ELM-based BJ boosting model can outperform traditional BJ model, two kinds of BJ boosting models proposed by Wang et al., RSF, and Cox proportional hazards model.

Coexisting Infantile Hepatic Hemangioma and Hepatoblastoma in a Neonate: A Case Report.

Infantile hepatic hemangioma and hepatoblastoma are the most common benign and malignant tumors of the liver in the neonatal and early childhood periods, respectively. However, the simultaneous occurrence of these 2 tumors in the same liver lesion is very rare. We report a case of a newborn infant diagnosed with a liver mass by ultrasound examination 4 days after birth. Serum alpha-fetoprotein (AFP) was elevated for his age (32,881.7 ng/mL). The liver mass was resected. Macroscopically, an externally protruding mass measuring 6 × 4 × 3.5 cm was identified. Microscopically, we observed the coexistence of infantile hepatic hemangioma and epithelial hepatoblastoma components within the tumor. The infantile hepatic hemangioma component was composed of multiple small vascular channels lined by endothelial cells. In the hepatoblastoma component, tumor cells were arranged in a 2- to 3-cell-thick trabecular formation. Immunohistochemistry indicated that the tumor cells in the infantile hepatic hemangioma component expressed CD34, CD31, FLI1, and ERG, and those in the hepatoblastoma component expressed hepatocyte, keratin AE1/AE3 and keratin 8, glypican 3, glutamine synthetase, and AFP. Pathological examination confirmed the presence of an infantile hepatic hemangioma combined with epithelial hepatoblastoma (fetal type). The boy did not undergo chemotherapy after the operation. Regular follow-up through serum AFP levels and liver ultrasound for 16 months to date show that the serum AFP levels decreased continuously to normal levels, with no signs of tumor recurrence or metastasis. The coexistence of infantile hepatic hemangioma and hepatoblastoma is rare. Hepatoblastoma should be considered in neonates with liver tumors and elevated AFP.

Reduction in Nitrogen Rate and Improvement of Nitrogen Use Efficiency without Loss of Peanut Yield by Regional Mean Optimal Rate of Chemical Fertilizer Based on a Multi-Site Field Experiment in the North China Plain.

It is important to quantify nutrient requirements and optimize fertilization to improve peanut yield and fertilizer use efficiency. In this study, a multi-site field trial was conducted from 2020 to 2021 in the North China Plain to estimate nitrogen (N), phosphorus (P), and potassium (K) uptake and requirements of peanuts, and to evaluate the effects of fertilization recommendations from the regional mean optimal rate (RMOR) on dry matter, pod yield, nutrient uptake, and fertilizer use efficiency. Results show that compared with farmer practice fertilization (FP), optimal fertilization (OPT) based on the RMOR increased peanut dry matter by 6.6% and pod yield by 10.9%. The average uptake rates of N, P, and K were 214.3, 23.3, and 78.4 kg/ha, respectively, with 76.0% N harvest index, 59.8% P harvest index, and 41.4% K harvest index. The OPT treatment increased N, P, and K uptake by 19.3%, 7.3%, and 11.0% compared with FP, respectively. However, the average of yield, nutrition uptake, and harvest indexes of N, P, and K were not significantly affected by fertilization. The peanut required 42.0 kg N, 4.6 kg P, and 15.3 kg K to produce 1000 kg of pods. The OPT treatment significantly improved the N partial factor productivity and N uptake efficiency but decreased the K partial factor productivity and K uptake efficiency. The present study demonstrates that fertilizer recommendations from RMOR improve N use efficiency, and reduce N and P fertilizer application without yield loss in regions with smallholder farmers, and the corresponding estimation of nutrient requirements helps to make peanut fertilization recommendations.

CCL3 in the bone marrow microenvironment causes bone loss and bone marrow adiposity in aged mice.

The central physiological role of the bone marrow renders bone marrow stromal cells (BMSCs) particularly sensitive to aging. With bone aging, BMSCs acquire a differentiation potential bias in favor of adipogenesis over osteogenesis, and the underlying molecular mechanisms remain unclear. Herein, we investigated the factors underlying age-related changes in the bone marrow and their roles in BMSCs' differentiation. Antibody array revealed that CC chemokine ligand 3 (CCL3) accumulation occurred in the serum of naturally aged mice along with bone aging phenotypes, including bone loss, bone marrow adiposity, and imbalanced BMSC differentiation. In vivo Ccl3 deletion could rescue these phenotypes in aged mice. CCL3 improved the adipogenic differentiation potential of BMSCs, with a positive feedback loop between CCL3 and C/EBPα. CCL3 activated C/EBPα expression via STAT3, while C/EBPα activated CCL3 expression through direct promoter binding, facilitated by DNA hypomethylation. Moreover, CCL3 inhibited BMSCs' osteogenic differentiation potential by blocking ß-catenin activity mediated by ERK-activated Dickkopf-related protein 1 upregulation. Blocking CCL3 in vivo via neutralizing antibodies ameliorated trabecular bone loss and bone marrow adiposity in aged mice. This study provides insights regarding age-related bone loss and bone marrow adiposity pathogenesis and lays a foundation for the identification of new targets for senile osteoporosis treatment.

Sensitive and Selective Detection of Enterococcus faecalis Using a New Turn-on Fluorogenic ß-glucosidase Substrate Combined with a Modified Selective Broth.

A new, simple-to-synthesize and sensitive turn-on fluorogenic substrate (CFMU-Glu) for ß-glucosidase activity was developed. This probe was based on a 7-hydroxycoumarin derivative (CFMU) that could emit green fluorescence and had the low pKa value of 5.61 ± 0.01. CFMU-Glu could be used for sensitive monitoring of the almond ßGLU and Enterococcus faecalis (E. faecalis) at the optimal pHs of 6.50 and 7.00, respectively. Moreover, a new sensitive and selective fluorogenic broth (PBF-B) for E. faecalis, utilizing CFMU-Glu and polymyxin B, was also developed. Polymyxin B was discovered to can significantly improve the detection selectivity and signal intensity. The proposed 4-four method using PBF-B and a microcentrifuge tube could provide fluorogenic detection limits of 5.01 × 104 and 1.0 × 105 CFU mL-1 by fluorescence microplate reader and naked eye, respectively; it could also provide a turn-on chromogenic detection limit of 1.0 × 106 CFU mL-1 by naked eye. The proposed method could detect 8 CFU mL-1 of E. faecalis in drinking water, Liangcha (herbal tea) and milk samples within 10 h, without pre-enrichment.

Antibiotic and metal resistance of Stenotrophomonas maltophilia isolates from Eboling permafrost of the Tibetan Plateau.

Whole-genome sequencing of pathogenic bacteria Stenotrophomonas maltophilia from a less polluted environment of permafrost can help understand the intrinsic resistome of both antibiotics and metals. This study aimed to examine the maximum minimum inhibitory concentration (MIC) of both antibiotics and metals, as well as antibiotic resistance genes and metal resistance genes annotated from whole-genome sequences. The permafrost S. maltophilia was sensitive to ciprofloxacin, tetracycline, streptomycin, and bacitracin, and resistant to chloramphenicol, trimethoprim-sulfamethoxazole, erythromycin, Zn2+, Ni2+, Cu2+, and Cr6+, with a lower maximum MIC, compared with clinical S. maltophilia. The former strain belonged to the lower antibiotic resistance gene (ARG) and metal resistance gene (MRG) clusters compared with the latter ones. The permafrost strain contained no or only one kind of ARG or MRG on a single genomic island, which explained the aforementioned lower maximum MIC and less diversity of ARGs or MRGs. The result indicated that the co-occurrence of antibiotic and metal resistance was due to a certain innate ability of S. maltophilia. The continuous human use of antibiotics or metals induced selective pressure, resulting in higher MIC and more diverse ARGs and MRGs in human-impacted environments.