Functional characterization of a TerC family protein of Riemerella anatipestifer in manganese detoxification and virulence.

Manganese (Mn) is an essential element for bacteria, but the overload of manganese is toxic. In a previous study, we showed that the cation diffusion facilitator protein MetA and the resistance-nodulation-division efflux pump MetB are responsible for Mn efflux in the bacterial pathogen Riemerella anatipestifer CH-1. However, whether this bacterium encodes additional manganese efflux proteins is unclear. In this study, we show that R. anatipestifer CH-1 encodes a tellurium resistance C (TerC) family protein with low similarity to other characterized TerC family proteins. Compared to the wild type (WT), the terC mutant of R. anatipestifer CH-1 (∆terC) is sensitive to Mn(II) intoxication. The ability of TerC to export manganese is higher than that of MetB but lower than that of MetA. Consistently, terC deletion (∆terC) led to intracellular accumulation of Mn2+ under excess manganese conditions. Further study showed that ∆terC was more sensitive than the WT to the oxidant hypoclorite but not to hydrogen peroxide. Mutagenesis studies showed that the mutant at amino acid sites of Glu116 (E116), Asp122 (D122), Glu245 (E245) Asp248 (D248), and Asp254 (D254) may be involved in the ability of TerC to export manganese. The transcription of terC was upregulated under excess manganese and downregulated under iron-limited conditions. However, this was not dependent on the manganese metabolism regulator MetR. In contrast to a strain lacking the manganese efflux pump MetA or MetB, the terC mutant is attenuated in virulence in a duckling model of infection due to increased sensitivity to duck serum. Finally, comparative analysis showed that homologs of TerC are distributed across the bacterial kingdom, suggesting that TerC exerts a conserved manganese efflux function.IMPORTANCERiemerella anatipestifer is a notorious bacterial pathogen of ducks and other birds. In R. anatipestifer, the genes involved in manganese efflux have not been completely identified, although MetA and MetB have been identified as two manganese exporters. Additionally, the function of TerC family proteins in manganese efflux is controversial. Here, we demonstrated that a TerC family protein helps prevent Mn(II) intoxication in R. anatipestifer and that the ability of TerC to export manganese is intermediate compared to that of MetA and MetB. Sequence analysis and mutagenesis studies showed that the conserved key amino sites of TerC are Glu116, Asp122, Glu245, Asp248, and Asp254. The transcription of terC was regulated by manganese excess and iron limitation. Finally, we show that TerC plays a role in the virulence of R. anatipestifer due to the increased sensitivity to duck serum, rather than the increased sensitivity to manganese. Taken together, these results expand our understanding of manganese efflux and the pathogenic mechanisms of R. anatipestifer.

Phospholipid and glycerolipid metabolism as potential diagnostic biomarkers for acute pancreatitis.

BACKGROUND: Acute pancreatitis (AP) is characterized as a systemic inflammatory condition posing challenges in diagnosis and prognosis assessment. Lipid metabolism abnormalities, especially triacylglycerol (TAG) levels, have been reported, indicating their potential as biomarkers in acute pancreatitis. However, the performance of the TAG cycle, including phospholipid and glycerolipid metabolism, in AP patients has not yet been reported. METHODS: This study enrolled 91 patients with acute biliary pancreatitis (ABP), 27 with hyperlipidaemic acute pancreatitis (HLAP), and 58 healthy controls (HCs), and their plasma phospholipid and glycerolipid levels were analyzed through liquid chromatography‒mass spectrometry. The phospholipid and glycerolipid contents of plasma collected from AP patients on the first, third, and seventh days of hospitalization were also measured. An orthogonal partial least squares discriminant analysis model served to differentiate the ABP, HLAP and HC groups, and potentially diagnostic lipids were evaluated via receiver operating characteristic curves in both the test and validation sets. Correlations between clinical data and lipids were conducted using Spearman's method. Clustering via the 'mfuzz' R package and the Kruskal‒Wallis H test were conducted to monitor changes during hospitalization. RESULTS: Compared with those in HCs, the levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidic acid (PA) were lower in AP patients, whereas the levels of phosphatidylinositol (PI) and phosphatidylglycerol (PG) showed the opposite trend. Interestingly, TAG levels were positively correlated with white blood cell counts in ABP patients, and TAGs containing 44-55 carbon atoms were highly correlated with plasma TAG levels in HLAP patients. Phospholipid levels exhibited an inverse correlation with AP markers, in contrast to glycerolipids, which demonstrated a positive correlation with these markers. Additionally, PE (O-16:0/20:4) and PE (18:0/22:6) emerged as potential biomarkers because of their ability to distinguish ABP and HLAP patients from HCs, showing area under the curve (AUC) values of 0.932 and 0.962, respectively. PG (16:0/18:2), PG (16:0/20:4), PE (P-16:0/20:2), PE (P-18:2/18:2), PE (P-18:1/20:3), PE (P-18:1/20:4), PE (O-16:0/20:4), and TAG (56:6/FA18:0) were significantly changed in ABP patients who improved. For HLAP patients, PC (18:0/20:3), TAG (48:3/FA18:1), PE (P-18:0/16:0), and TAG (48:4/FA18:2) showed different trends in patients with improvement and deterioration, which might be used for prognosis. CONCLUSIONS: Phospholipids and glycerolipids were found to be potential biomarkers in acute pancreatitis, which offers new diagnostic and therapeutic insights into this disease.

Efficacy and safety of laparoscopic common bile duct exploration via choledochotomy with primary closure for the management of acute cholangitis caused by common bile duct stones.

BACKGROUND: T-tube drainage after laparoscopic common bile duct exploration (LCBDE) has been demonstrated to be safe and effective for patients with acute cholangitis caused by common bile duct stones (CBDSs). The outcomes after LCBDE with primary closure in patients with CBDS-related acute cholangitis are unknown. The present study aimed to evaluate the efficacy and safety of LCBDE with primary closure for the management of acute cholangitis caused by CBDSs. METHODS: Between June 2015 and June 2020, 368 consecutive patients with choledocholithiasis combined with cholecystolithiasis, who underwent laparoscopic cholecystectomy (LC) + LCBDE in our department, were retrospectively reviewed. A total of 193 patients with CBDS-related acute cholangitis underwent LC + LCBDE with primary closure of the CBD (PC group) and 62 patients underwent LC + LCBDE followed by T-tube placement (T-tube group). A total of 113 patients who did not have cholangitis were excluded. The clinical data were compared and analyzed. RESULTS: There was no mortality in either group. No significant differences were noted in morbidity, bile leakage rate, retained CBD stones, or readmission rate within 30 days between the two groups. Compared with the T-tube group, the PC group avoided T-tube-related complications and had a shorter operative time (121.12 min vs. 143.37 min) and length of postoperative hospital stay (6.59 days vs. 8.81 days). Moreover, the hospital expenses in the PC group were significantly lower than those in the T-tube group ($4844.47 vs. $5717.22). No biliary stricture occurred during a median follow-up of 18 months in any patient. No significant difference between the two groups was observed in the rate of stone recurrence. CONCLUSIONS: LCBDE with primary closure is a safe and effective treatment for cholangitis caused by CBDSs. LCBDE with primary closure is not inferior to T-tube drainage for the management of CBDS-related acute cholangitis in suitable patients.

Intestinal microbiota: a new force in cancer immunotherapy.

Cancer displays high levels of heterogeneity and mutation potential, and curing cancer remains a challenge that clinicians and researchers are eager to overcome. In recent years, the emergence of cancer immunotherapy has brought hope to many patients with cancer. Cancer immunotherapy reactivates the immune function of immune cells by blocking immune checkpoints, thereby restoring the anti-tumor activity of immune cells. However, immune-related adverse events are a common complication of checkpoint blockade, which might be caused by the physiological role of checkpoint pathways in regulating adaptive immunity and preventing autoimmunity. In this context, the intestinal microbiota has shown great potential in the immunotherapy of cancer. The intestinal microbiota not only regulates the immune function of the body, but also optimizes the therapeutic effect of immune checkpoint inhibitors, thus reducing the occurrence of complications. Therefore, manipulating the intestinal microbiota is expected to enhance the effectiveness of immune checkpoint inhibitors and reduce adverse reactions, which will lead to new breakthroughs in immunotherapy and cancer management. Video abstract.

The role of microbiota in the development of colorectal cancer.

Colorectal cancer is the third largest cancer in worldwide and has been proven to be closely related to the intestinal microbiota. Many reports and clinical studies have shown that intestinal microbial behavior may lead to pathological changes in the host intestines. The changes can be divided into epigenetic changes and carcinogenic changes at the gene level, which ultimately promote the production and development of colorectal cancer. This article reviews the pathways of microbial signaling in the intestinal epithelial barrier, the role of microbiota in inflammatory colorectal tumors, and typical microbial carcinogenesis. Finally, by gaining a deeper understanding of the intestinal microbiota, we hope to achieve the goal of treating colorectal cancer using current microbiota technologies, such as fecal microbiological transplantation.

Star Image Prediction and Restoration under Dynamic Conditions.

The star sensor is widely used in attitude control systems of spacecraft for attitude measurement. However, under high dynamic conditions, frame loss and smearing of the star image may appear and result in decreased accuracy or even failure of the star centroid extraction and attitude determination. To improve the performance of the star sensor under dynamic conditions, a gyroscope-assisted star image prediction method and an improved Richardson-Lucy (RL) algorithm based on the ensemble back-propagation neural network (EBPNN) are proposed. First, for the frame loss problem of the star sensor, considering the distortion of the star sensor lens, a prediction model of the star spot position is obtained by the angular rates of the gyroscope. Second, to restore the smearing star image, the point spread function (PSF) is calculated by the angular velocity of the gyroscope. Then, we use the EBPNN to predict the number of iterations required by the RL algorithm to complete the star image deblurring. Finally, simulation experiments are performed to verify the effectiveness and real-time of the proposed algorithm.

Krüppel-like factor 8 promotes cancer stem cell-like traits in hepatocellular carcinoma through Wnt/ß-catenin signaling.

Krüppel-like factor 8 (KLF8) is highly expressed in hepatocellular carcinoma (HCC) and contributes to tumor initiation and progression by promoting HCC cell proliferation and invasion. However, the role of KLF8 in liver cancer stem cells (LCSCs) is not known. In the current study, we investigated the role of KLF8 in LCSCs to determine if KLF8 is a novel marker of these cells. We found that KLF8 was highly expressed in primary HCC tumors, distant migrated tissues, and LCSCs. Patients with high KLF8 expression had a poor prognosis. KLF8 promoted stem cell-like features through activation of the Wnt/ß-catenin signaling pathway. Cell apoptosis was significantly increased in HCC cells with knockdown of KLF8 compared with the control cells when treated with the same doses of sorafenib or cisplatin. Taken together, our study shows that KLF8 plays a potent oncogenic role in HCC tumorigenesis by maintaining stem cell-like features through activation of the Wnt/ß-catenin signaling pathway and promoting chemoresistance. Thus, targeting KLF8 may provide an effective therapeutic approach to suppress tumorigenicity of HCC. © 2016 Wiley Periodicals, Inc.

A clinical nomogram for predicting small bowel obstruction after extubation after radical resection of esophageal cancer and jejunostomy.

BACKGROUND: Small bowel obstruction after extubation is among the most serious complications of radical esophageal cancer and jejunostomy resection. This study aimed to explore the risk factors and treatment methods for small bowel obstruction after extubation and construct a predictive model to guide its clinical management. METHODS: Clinical data for 514 patients who underwent esophagectomy with jejunostomy for esophageal cancer were collected. A nomogram was constructed using the independent risk factors for small bowel obstruction after extubation determined on multivariable logistic regression analysis, and a subgroup analysis was performed of the treatment methods for the 61 patients with small bowel obstruction after extubation. RESULTS: The nomogram incorporated the independent risk factors for small bowel obstruction after extubation (gastrointestinal function recovery [P < .001], postoperative albumin reduction ratio [P = .009], and serious postoperative complications [P < .001]) in the multivariable logistic regression analysis. The final model had an area under the curve of 0.829 (95% confidence interval, 0.775-0.883). The calibration plots demonstrated high concordance between the predicted and actual probabilities. The model demonstrated excellent discriminatory power for internal and time validation, with adjusted C-statistics of 0.821 and 0.810 (95% confidence interval, 0.686-0.933), respectively. In the subgroup analysis, an abnormal anion gap (P = .016) and low serum albumin level (P = .005) were associated with recurrent small bowel obstruction. The model's area under the curve was 0.815 (95% confidence interval, 0.683-0.948). The probability of recurrence among patients with small bowel obstruction after extubation was 78.3% when the 2 risk factors were present. CONCLUSION: The clinical nomogram based on small bowel obstruction after extubation predictors recommends aggressive surgical intervention for patients with small bowel obstruction after extubation and an abnormal anion gap and low serum albumin level at admission.

USP35 promotes HCC development by stabilizing ABHD17C and activating the PI3K/AKT signaling pathway.

S-palmitoylation is a reversible protein lipidation that controls the subcellular localization and function of targeted proteins, including oncogenes such as N-RAS. The depalmitoylation enzyme family ABHD17s can remove the S-palmitoylation from N-RAS to facilitate cancer development. We previously showed that ABHD17C has oncogenic roles in hepatocellular carcinoma (HCC) cells, and its mRNA stability is controlled by miR-145-5p. However, it is still unclear whether ABHD17C is regulated at the post-translational level. In the present study, we identified multiple ubiquitin-specific proteases (USPs) that can stabilize ABHD17C by inhibiting the ubiquitin-proteasome-mediated degradation. Among them, USP35 is the most potent stabilizer of ABHD17C. We found a positive correlation between the elevated expression levels of USP35 and ABHD17C, together with their association with increased PI3K/AKT pathway activity in HCCs. USP35 knockdown caused decreased ABHD17C protein level, impaired PI3K/AKT pathway, reduced proliferation, cell cycle arrest, increased apoptosis, and mitigated migration and invasion. USP35 can interact with and stabilize ABHD17C by inhibiting its ubiquitination. Overexpression of ABHD17C can rescue the defects caused by USP35 knockdown in HCC cells. In support of these in vitro observations, xenograft assay data also showed that USP35 deficiency repressed HCC development in vivo, characterized by reduced proliferation and disrupted PI3K/AKT signaling. Together, these findings demonstrate that USP35 may promote HCC development by stabilization of ABHD17C and activation of the PI3K/AKT pathway.

Continuous Homogeneous Catalytic Oxidation of C-H Bonds by Metal-Free Carbon Dots with a Poly(ascorbic acid) Structure.

The activation of the C-H bond, a necessary step to get high-value-added compounds, is one of the most important issues in modern catalysis. Combining the advantages of both homogeneous and heterogeneous catalysis, a certain continuous homogeneous process should be one of the ideal routes for the catalytic activation of C-H bonds. Here, through machine learning (ML), we predicted and fabricated metal-free carbon dot (C-Dot) homogeneous catalysts for C-H bond oxidation. These C-Dots have an ascorbic acid unit based polymer-like structure with a polymerization degree in the range of 3-10. With C-Dots as the catalyst, three groups (aliphatic, aromatic, and cycloalkanes) of 10 hydrocarbon molecules were tested, proving its generality for the catalytic oxidation of the C-H bond. A typical example of cyclohexane that was selectively oxidized to adipic acid (AA) by using a circulation and phase-transfer process demonstrates its critical advantages, such as the continuous and large-scaled producing ability of the homogeneous catalysis process. The one-pass conversion efficiency of cyclohexane to AA reaches 77.49% with selectivity up to 84.24% in 4 h. The yield of 16.32% per hour is about 4 times over that of modern technology. Theoretical calculations suggested that the O2 activation on C-Dots plays a crucial role in determining the reaction rate of the entire catalytic oxidation process of cyclohexane.

Exosomal DLX6-AS1 from hepatocellular carcinoma cells induces M2 macrophage polarization to promote migration and invasion in hepatocellular carcinoma through microRNA-15a-5p/CXCL17 axis.

BACKGROUND: Hepatocellular carcinoma (HCC) cells-secreted exosomes (exo) could stimulate M2 macrophage polarization and promote HCC progression, but the related mechanism of long non-coding RNA distal-less homeobox 6 antisense 1 (DLX6-AS1) with HCC-exo-mediated M2 macrophage polarization is largely ambiguous. Thereafter, this research was started to unearth the role of DLX6-AS1 in HCC-exo in HCC through M2 macrophage polarization and microRNA (miR)-15a-5p/C-X-C motif chemokine ligand 17 (CXCL17) axis. METHODS: DLX6-AS1, miR-15a-5p and CXCL17 expression in HCC tissues and cells were tested. Exosomes were isolated from HCC cells with overexpressed DLX6-AS1 and co-cultured with M2 macrophages. MiR-15a-5p/CXCL17 down-regulation assays were performed in macrophages. The treated M2 macrophages were co-cultured with HCC cells, after which cell migration, invasion and epithelial mesenchymal transition were examined. The targeting relationships between DLX6-AS1 and miR-15a-5p, and between miR-15a-5p and CXCL17 were explored. In vivo experiment was conducted to detect the effect of exosomal DLX6-AS1-induced M2 macrophage polarization on HCC metastasis. RESULTS: Promoted DLX6-AS1 and CXCL17 and reduced miR-15a-5p exhibited in HCC. HCC-exo induced M2 macrophage polarization to accelerate migration, invasion and epithelial mesenchymal transition in HCC, which was further enhanced by up-regulated DLX6-AS1 but impaired by silenced DLX6-AS1. Inhibition of miR-15a-5p promoted M2 macrophage polarization to stimulate the invasion and metastasis of HCC while that of CXCL17 had the opposite effects. DLX6-AS1 mediated miR-15a-5p to target CXCL17. DLX6-AS1 from HCC-exo promoted metastasis in the lung by inducing M2 macrophage polarization in vivo. CONCLUSION: DLX6-AS1 from HCC-exo regulates CXCL17 by competitively binding to miR-15a-5p to induce M2 macrophage polarization, thus promoting HCC migration, invasion and EMT.

Hydroxyl-terminated carbon dots for efficient conversion of cyclohexane to adipic acid.

Adipic acid (HOOC(CH2)4COOH, AA) is a crucial chemical in industrial manufactures and mainly produced by the oxidation of cyclohexane with air and nitric acid via a homogeneous two step path in industry. However, the conventional industrial method inevitably results in the generation of nitrous oxide (N2O, etc.), which is the main cause of the greenhouse effect and ozone depletion. Herein, we engineered five kinds of carbon dots (CDs) with different oxygen-containing functional groups on their surfaces, which were directly used as catalysts over the selective catalytic oxidation of cyclohexane. Among the five CDs, the hydroxyl-terminated CDs show the best catalytic activity with the conversion of cyclohexane ~ 29.43% and selectivity to AA ~ 95.89% under 130 °C, 20 atm with oxygen as oxidant. With the CDs directly as catalyst, the one-step efficient catalytic oxidation reaction for cyclohexane to AA was realized to replace the two-step routes. In addition, the density functional theory (DFT) computational results were performed to further prove that the more quantity of hydroxyl on CDs and the higher O2 pressure can boost the higher catalytic activity of CDs over oxidation of cyclohexane.

Efficient photocatalytic water splitting through titanium silicalite stabilized CoO nanodots.

Water can be split into hydrogen (H2) and hydrogen peroxide (H2O2) in an environment-friendly manner through photocatalysis by CoO, which is a promising strategy to alleviate the energy crisis. However, the stability of CoO remains a great challenge because of the oxidation effect of the product H2O2. Herein, titanium silicalite-1 (TS-1) was employed as a framework to obtain and anchor monodisperse CoO nanodots, improve CoO photocatalytic performance, and efficiently separate the oxidizing species from CoO by adsorbing the resulting H2O2. As a result, TS-1 prevented CoO from aggregation, surface oxidation, and rapid inactivation. CoO-TS-1 showed H2 and H2O2 production rates of 1460 µmol h-1 gCoO-1 and 1390 µmol h-1 gCoO-1, respectively, with a high photostability for about 168 h. In addition, the efficiently harvested H2O2 was directly used in the oxidation of cyclohexane to cyclohexanol and cyclohexanone with a selectivity of up to 89.48%. This work paves a new way for the design of an efficient and stable photocatalyst as well as product utilization.

A Facile and Efficient Method to Fabricate Highly Selective Nanocarbon Catalysts for Oxidative Dehydrogenation.

Carbon nanotubes (CNTs) were used in oxidative dehydrogenation (ODH) reactions. Quinone groups on the CNT surface were identified as active sites for the dehydrogenation pathway. Liquid-phase oxidation with HNO3 is one way to generate various oxygen functionalities on the CNT surface but it produces a large amount of acid waste, limiting its industrial application. Here, a facile and efficient oxidative method to prepare highly selective CNT catalysts for ODH of n-butane is reported. Magnesium nitrate salts as precursors were used to produce defect-rich CNTs through solid-phase oxidation. Skeleton defects induced on the CNT surface resulted in the selective formation of quinone groups active for the selective dehydrogenation. The as-prepared catalyst exhibited a considerable selectivity (58 %) to C4 olefins, which is superior to that of CNTs oxidized with liquid HNO3 . Through the introduction of MgO nanoparticles on the CNT surface, the desorption of alkenes can be accelerated dramatically, thus enhancing the selectivity. This study provides an attractive way to develop new nanocarbon catalysts.

Celastrol suppresses obesity process via increasing antioxidant capacity and improving lipid metabolism.

High fat diet, as an important risk factor, plays a pivotal role in atherosclerotic process. Celastrol is one of the active triterpenoid compounds with antioxidative and anti-inflammatory characters. The aims of this study were to evaluate the effect of celastrol on weight, blood lipid and oxidative injury induced by high fat emulsion, and investigate its potential pharmacological mechanisms. Male Sprague-Dawley rats were fed with high fat emulsion for 6 wk to mimic high fat mediated oxidative injury. The effects of celastrol on weight and blood lipid were evaluated, and its mechanisms were disclosed by applying western blot, ELISA and assay kits. Long-term consumption of high fat emulsion could significantly increase weight by enhancing total cholesterol (TC), triacylglycerol (TG), apolipoprotein B (Apo B), low-density lipoprotein cholesterol (LDL-c) levels, attenuating ATP-binding cassette transporter A1 (ABCA1) expression, and decreasing the levels of high-density lipoprotein cholesterol (HDL-c) and apolipoprotein A-I (Apo A-I), and inhibit antioxidant enzymes activities, improve nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. Comparing with model group, celastrol was able to effectively suppress weight and attenuate high fat mediated oxidative injury by improving ABCA1 expression, reducing the levels of TC, TG, LDL-c and Apo B in plasma, and increasing antioxidant enzymes activities and inhibiting NADPH oxidase activity, and decreasing the serum levels of Malondialdehyde (MDA) and reactive oxygen species in dose-dependent way. These data demonstrated that celastrol was able to effectively suppress weight and alleviate high-fat mediated cardiovascular injury via mitigating oxidative stress and improving lipid metabolism.