Genetic components of Escherichia coli involved in its complex prey-predator interaction with Myxococcus xanthus.

Myxococcus xanthus and Escherichia coli represent a well-studied microbial predator-prey pair frequently examined in laboratory settings. While significant progress has been made in comprehending the mechanisms governing M. xanthus predation, various aspects of the response and defensive mechanisms of E. coli as prey remain elusive. In this study, the E. coli MG1655 large-scale chromosome deletion library was screened, and a mutant designated as ME5012 was identified to possess significantly reduced susceptibility to predation by M. xanthus. Within the deleted region of ME5012 encompassing seven genes, the significance of dusB and fis genes in driving the observed phenotype became apparent. Specifically, the deletion of fis resulted in a notable reduction in flagellum production in E. coli, contributing to a certain level of resistance against predation by M. xanthus. Meanwhile, the removal of dusB in E. coli led to diminished inducibility of myxovirescin A production by M. xanthus, accompanied by a slight decrease in susceptibility to myxovirescin A. These findings shed light on the molecular mechanisms underlying the complex interaction between M. xanthus and E. coli in a predatory context.

Construction of a competing risk model for disease-free survival of patients with non-muscle invasive bladder cancer / 现代泌尿外科杂志

【Objective】 To construct an easy-to-use individual survival prognostic tool based on competing risk analyses to predict the risk of 1-, 2- and 3- year recurrence for patients with non-muscle invasive bladder cancer (NMIBC). 【Methods】 The follow-up data of 419 NMIBC patients were obtained. The patients were randomly divided into training cohort (n=293) and validation cohort (n=126). The variables included age at diagnosis, sex, history of smoking, tumor number, tumor size, histolo-gic grade, pathological stage, and bladder perfusion drug. The cumulative incidence function (CIF) of recurrence was estimated using all variables in the training cohort and potential prognostic variables were determined with Gray’s test. The Fine-Gray subdistribution proportional hazard approach was used as a multivariate competitive risk analysis to identify independent pro-gnostic variables. A competing risk nomogram was developed to predict the recurrence. The performance of the competing risk model was evaluated with the area under the receiver operating characteristic curve (AUC), calibration curve, and Brier score. 【Results】 Five independent prognostic factors including age, number of tumors, tumor size, histologic grade and pathological stage were used to construct the competing risk model. In the validation cohort, the AUC of 1-, 2- and 3- year recurrence were 0.895 (95%CI: 0.831-0.959), 0.861(95%CI: 0.774-0.948) and 0.827(95%CI: 0.721-0.934), respectively, indicating that the model had a high predictive performance. 【Conclusion】 We successfully constructed a competing risk model to predict the risk of 1-, 2- and 3-year recurrence for NMIBC patients. It may help clinicians to improve the postoperative management of patients.

The food preservative sodium propionate induces hyperglycaemic state and neurological disorder in zebrafish.

Propionate is an effective mould inhibitor widely used as a food preservative. In this study, we used zebrafish to explore the adverse effects of long-term exposure to low concentrations of sodium propionate and the underlying molecular mechanisms (from larvae to adult). When exposed for 3 months, we found that blood glucose, total cholesterol, and triglyceride levels increased, and zebrafish developed a hyperglycaemic state. New tank test results showed depression in zebrafish reduced 5-hydroxytryptamine levels in the brain and damaged the dopamine system. At the same time, the results of the color preference test showed that zebrafish had cognitive impairments. In addition, Hypothalamic-Pituitary-Adrenal axis analysis revealed abnormal gene expression, increased cortisol levels, and reduced glucocorticoid receptor mRNA levels, which were consistent with depressive behavior. We also observed abnormal transcription of inflammatory and apoptotic factors. Overall, we found that chronic exposure to sodium propionate induces depressive symptoms. This may be related to the activation of the HPA axis by the hyperglycaemic state, thereby inducing inflammation and disrupting the dopaminergic system. In summary, this study provides theoretical and technical support for the overlap of the emotional pathogenesis associated with diabetes.

Calycosin may Alleviate Ang II-Induced Pro-proliferative Effects on Glomerular Mesangial Cells via Partially Inhibiting Autophagy and ERK Signaling Pathway.

Over-expression of angiotensin II (Ang II) is an important reason for the development of chronic kidney disease. Calycosin is the active component of traditional Chinese medicine astragali radix. The present work aims to explore whether calycosin could affect the growth and apoptosis ability of the Ang II treated glomerular mesangial cells and the underlying mechanism. Human glomerular mesangial cells (GMCs) were cultured and treated by Ang II and 0, 0.1, 1, or 10 µM calycosin, and the viability and proliferation of the cells were determined by methyl thiazolyl tetrazolium (MTT) and 5-ethynil-2'-deoxyuridine (EdU) staining; moreover, the apoptosis of the cells was examined by flow cytometry assay; furthermore, the expression levels of extracellular signal-regulated kinase (ERK), p-ERK, anti-apoptotic factor Bcl-2, as well as pro-apoptotic factor Bax have been examined by Western blot (WB) methods; finally, the expression of autophagic markers in each group was examined by WB and immunocytochemistry methods. We found that Ang II increased viability and proliferation, meanwhile inhibited apoptosis of the GMCs; furthermore, 1 and 10 µM calycosin significantly inhibited the growth and promoted the apoptosis of the GMCs treated by Ang II; moreover, calycosin also inhibited ERK signaling in mesangial cells activated by Ang II treatment; Finally, calycosin could inhibit Ang II induced autophagy of GMCs in a dose-dependent manner. In conclusion, calycosin may alleviate Ang II-induced pro-proliferative and anti-apoptotic effects on glomerular mesangial cells at least partially via inhibiting autophagy and ERK signaling pathway, suggesting that calycosin may function as a potential alternative medication for the management of chronic kidney diseases.

α-Mangostin reduced the viability of A594 cells in vitro by provoking ROS production through downregulation of NAMPT/NAD.

α-Mangostin (MAN) is a bioactive compound isolated from the inedible pericarp of a tropical fruit mangosteen (Garcinia mangostana Linn). It exhibits notable therapeutic potentials on lung cancers, but the underlying mechanisms are still largely unknown. This study was designed to further explore the mechanisms involved in cytotoxicity of MAN on A549 cells. Apoptosis and cell cycle distribution were analyzed by flow cytometry methods. The fluorescent probes DCFH-DA and JC-1 were used to assess the intracellular reactive oxidative species (ROS) and mitochondrial membrane potential statuses, respectively. The regulation of MAN on relevant pathways was investigated by immunoblotting assays. The results obtained indicated that MAN caused significant apoptosis and cell cycle arrest in A549 cells, which eventually resulted in inhibition on cell proliferation in vitro. All these phenomena were synchronized with escalated oxidative stress and downregulation of nicotinamide phosphoribosyltransferase/nicotinamide adenine dinucleotide (NAMPT/NAD). Supplementation with nicotinamide mononucleotide (NMN) and N-acetylcysteine (NAC) efficiently eased MAN-induced ROS accumulation, and potently antagonized MAN-elicited apoptosis and cell cycle arrest. The pro-apoptotic effect of MAN was further confirmed by increased expressions of cleaved caspase 3, 6, 7, and 9, and its effect on cell cycle progression was validated by the altered expressions of p-p38, p-p53, CDK4, and cyclin D1. The immunoblotting assays also demonstrated that NAC/NMN effectively restored these molecular changes elicited by MAN treatment. Collectively, this study revealed a unique anti-tumor mechanism of MAN by provoking ROS production through downregulation of NAMPT/NAD signaling and further validated MAN as a potential therapeutic reagent for lung cancer treatment.

Development and Validation of a Low-Cost and Simple Simulator for Microlaryngeal Surgery.

OBJECTIVES: The simulation of microlaryngeal skills is rarely seen in surgical training, but it is particularly important in phonomicrosurgery. This study described and validated the laryngeal surgical simulator through surgical training. METHODS: A simple and low-cost simulator was developed for the fixation of the suspension laryngoscope and porcine larynges. Twenty participants with work skills and experience did preparation before training, and performed suture and carbon dioxide (CO2) laser cordectomy for simulator evaluation. The results were proposed by the aspects of time taken for each procedure, the global rating scale, a procedure-specific assessment, and a post-simulation questionnaire. RESULTS: All participants completed the preparation within 9 minutes and reached the conclusion that the microlaryngeal surgical simulator was helpful in improving their surgical skills. The performance of experts was superior to that of novices in both suture and CO2 laser cordectomy. CONCLUSION: This simulator could be easily assembled and was successfully validated by microlaryngeal surgical training both subjectively and objectively. It may be helpful to clinicians in microlaryngeal skills.

Inhibition of NF-κB pathway in fibroblast-like synoviocytes by α-mangostin implicated in protective effects on joints in rats suffering from adjuvant-induced arthritis.

α-Mangostin (MG) is a bioactive compound isolated from mangosteen. This study was aimed to investigate effects of MG on adjuvant-induced arthritis (AA) in rats and decipher the underlying mechanisms. Clinical severity of AA was evaluated by paw oedema, arthritis score, and hematological parameters. Digital radiography (DR) and histological examinations were employed to assess joints destructions. Immune functions were evaluated by T cell subsets distribution. Effects on NF-κB pathway were investigated by immunohistochemical, western-blot and immunofluorescence methods both in vivo and vitro. It was found MG possessed superior anti-inflammatory effects in vivo, suggested by attenuated paw swelling, reduced inflammatory cells infiltration and decreased the secretion of TNF-α and IL-1ß in serum. Meanwhile MG inhibited fibrous hyperplasia, synovial angiogenesis, cartilage and bone degradation in AA rats. Although MG exerted little effects on CD4+ population, it greatly decreased IFN-γ positive cells and promoted expression of FOXP3 in immune organs, indicating restoration of Th1/Treg cells ratio and recovery of immune homeostasis in vivo. Inhibition of NF-κB induced by MG was indicated by reduced the expression of p-p65 and VEGF in synovium. In vitro experiments found MG at 10 µg/ml significantly suppressed the expression and phosphorylation of key proteins implicated in NF-κB pathway and inhibited nucleus translocation of p65. These changes led to increased apoptosis and proliferation inhibition of HFLS-RA cells. The results demonstrated regulation of immune functions was deeply involved in the therapeutic actions of MG on AA, and it's inhibition on NF-κB in fibroblast-like synoviocytes was associated to the protective effects on joints.

Reactive oxygen species mediated NF-κB/p38 feedback loop implicated in proliferation inhibition of HFLS-RA cells induced by 1,7-dihydroxy-3,4-dimethoxyxanthone.

1,7-Dihydroxy-3,4-dimethoxyxanthone (XAN) is a bioactive compound isolated from Securidaca inappendiculata Hassk. and exerts the inhibitory effects on fibroblast-like synoviocytes by targeting NF-κB and p38. This study was designed to elucidate mechanisms underlying the divergent regulation on the two pathways in HFLS-RA cells by XAN. Expressions of hallmark proteins and transcription of GADD45α mRNA were determined by Western-blot and RT-qPCR methods, respectively. Fluorescence staining was employed to evaluate intracellular oxidative stress. Effects of XAN and N-acetyl-l-cysteine (NAC) on the proliferation of cells were investigated by MTT assay, and pro-apoptotic effects of XAN were assessed by Annexin V-FITC/PI method. It was found XAN blocked NF-κB signaling in HFLS-RA cells shortly after treatment. Moreover, it up-regulated both transcription and expression of GADD45α, and subsequently activated p38 pathway. As time went on, XAN significantly promoted the generation of reactive oxygen species (ROS), which accompanied with sustained up-regulation of p-p38 and increased apoptosis. 48H later, dual-effects of XAN on NF-κB and p38 were reversed. As activation of p38 and increased apoptosis induced by XAN were antagonized by NAC, they were deemed as ROS mediated effects. Furthermore, the accumulated ROS should also account for the activation of NF-κB in the late stage of treatments via interfering in p38/MSK1/NF-κB feedback. Altogether, these findings suggested XAN-induced ROS contributed great importance to the proliferation inhibition of HFLS-RA cells by mediating NF-κB/p38 feedback loop and apoptosis, which provided us a panoramic view of potential target in the therapy of RA by XAN.

Astragaloside IV downregulates the expression of MDR1 in Bel­7402/FU human hepatic cancer cells by inhibiting the JNK/c­Jun/AP­1 signaling pathway.

Previous studies demonstrated that astragaloside IV (ASIV) is a potential P­glycoprotein (P­gp)­mediated multidrug resistance (MDR) reversal agent through mechanisms involving downregulation of the gene expression of mdr1. In order to investigate whether the c­Jun N­terminal kinase (JNK) signaling pathway is involved in the mechanism underlying ASIV­induced downregulated the expression of mdr1, the present study used 5­fluorouracil­resistant Bel­7402/FU human hepatic cancer cells as target cells. ASIV (0.1 mM) decreased the protein expression of phosphorylated (p)­JNK and p­c­Jun in the Bel­7402/FU cells, as determined using western blot analysis. Treatment with the JNK pathway inhibitor, SP600125, at a concentration of 11 µM, decreased the mRNA expression levels of mdr1 and P­gp, as determined using reverse transcription­quantitative polymerase chain reaction and western blot analyses, and similar effects were observed following exposure to ASIV. Furthermore, electrophoretic mobility shift assays demonstrated that the DNA­binding activity of activator protein­1 (AP­1) was decreased by 0.1 mM ASIV or 11 µM SP600125. Flow cytometric analysis revealed that 0.1 mM ASIV or 11 µM SP600125 increased the intracellular accumulation of fluorescent P­gp substrates, including rhodamine 123. Taken together, these results indicated that ASIV reversed the drug resistance of Bel­7402/FU cells by downregulating the expression of mdr1 via inhibition of the JNK/c­Jun/AP­1 signaling pathway.

[Neuroprotective effect of Nogo-66 receptor silencing in preterm rats with brain injury caused by intrauterine infection].

OBJECTIVE: To investigate the effect of Nogo-66 receptor (NgR) silencing with specific small interfering RNA (siRNA) on brain injury repair in preterm rats with brain injury caused by intrauterine infection and related mechanism of action. METHODS: The pregnant Sprague-Dawley rats (with a gestational age of 15 days) were selected, and premature delivery was induced by RU486 or lipopolysaccharide (LPS). The preterm rats delivered by those treated with RU486 were selected as the control group. The preterm rats with brain injury caused by intrauterine infection induced by LPS were divided into model, empty vector, and NgR-siRNA groups, with 36 rats in each group. The rats in the control and model groups were given routine feeding only, and those in the empty vector and NgR-siRNA groups were given an injection of lentiviral empty vector or NgR-siRNA lentivirus via the lateral ventricle on postnatal day 1 (P1) and then fed routinely. On P3, P7, and P14, 8 rats in each group were randomly selected and sacrificed to harvest the brain tissue. RT-PCR was used to measure the mRNA expression of NgR. Western blot was used to to measure the protein expression of active RhoA. The immunofluorescence histochemistry was used to determine the degree of activation of microglial cells and the morphology of oligodendrocyte precursor cells (OPCs). Hematoxylin and eosin staining was used to observe the pathological changes in brain tissue. The behavioral score was evaluated on P30. RESULTS: On P3, the NgR-siRNA group had significantly lower mRNA expression of NgR and protein expression of active RhoA in brain tissue than the model and empty vector groups (P<0.05). In each group, the mRNA expression of NgR was positively correlated with the protein expression of active RhoA (P<0.05). The results of immunofluorescence histochemistry showed that on P3, the NgR-siRNA group had a significantly reduced fluorescence intensity of the microglial cells labeled with CD11b compared with the model and empty vector groups (P<0.05). The OPCs labeled with O4 antibody in the four groups were mainly presented with tripolar cell morphology. The results of pathological examination showed a normal structure of white matter with clear staining in the periventriclar area in the control group, a loose structure of white matter with disorganized fibers and softening lesions in the model and empty vector groups, and a loose structure of white matter with slightly disorganized fibers, slight gliocyte proliferation, and no significant necrotic lesions in the NgR-siRNA group. As for the behavioral score, compared with the model and empty vector groups, the NgR-siRNA group had a higher score in the suspension test, a longer total activity distance, and greater mean velocity and number of squares crossed, as well as a shorter time of slope test and a shorter time and distance of activity in the central area (P<0.05), while there were no significant differences in these parameters between the NgR-siRNA and control groups (P>0.05). CONCLUSIONS: NgR silencing with specific siRNA can effectively silence the expression of NgR in pertem rats with brain injury caused by interauterine infection and has a significant neuroprotective effect in brain injury repair.

Regulation of MAPKs Signaling Contributes to the Growth Inhibition of 1,7-Dihydroxy-3,4-dimethoxyxanthone on Multidrug Resistance A549/Taxol Cells.

1,7-Dihydroxy-3,4-dimethoxyxanthone (XAN) is a bioactive compound isolated from Securidaca inappendiculata Hassk. and validated with antiproliferative activities on a panel of cancer cell lines. This study was designed to investigate its growth inhibitory effects on multidrug resistance (MDR) non-small cell lung carcinoma (NSCLC) cell line A549/Taxol and explore the possible linkage between modulation of MAPKs and the bioactivities. Its growth inhibitory potency on the cells was estimated by MTT assay, and flow cytometric analysis was employed to investigate its potential cell cycle arrest and proapoptosis effects. Expressions of hallmark proteins were assessed by Western-Blot method. The results showed A549/Taxol cells were sensitive to XAN. XAN inhibited the proliferation of A549/Taxol cells in the time and concentration dependent manners. It acted as a potent inducer of apoptosis and cell cycle arrest in the cells. Western-Blot investigation validated the proapoptosis and cell cycle arrest activities of XAN and the potential of MDR reversion. Upregulation of p38 by XAN, which accounted for the cell cycle arrest at G2 phase, and the downregulation of ERK associated with the proapoptosis activity were also revealed. Further analysis found p53 may be the central role mediated the bioactivities of MAPKs in A549/Taxol cells. Based on these evidences, a conclusion has been deduced that XAN could be a potential agent for MDR NSCLC therapy targeting specifically MAPKs.

Dosing-time contributes to chronotoxicity of clofarabine in mice via means other than pharmacokinetics.

To evaluate the time- and dose-dependent toxicity of clofarabine in mice and to further define the chronotherapy strategy of it in leukemia, we compared the mortality rates, LD50s, biochemical parameters, histological changes and organ indexes of mice treated with clofarabine at various doses and time points. Plasma clofarabine levels and pharmacokinetic parameters were monitored continuously for up to 8 hours after the single intravenous administration of 20 mg/kg at 12:00 noon and 12:00 midnight by high performance liquid chromatography (HPLC)-UV method. Clofarabine toxicity in all groups fluctuated in accordance with circadian rhythms in vivo. The toxicity of clofarabine in mice in the rest phase was more severe than the active one, indicated by more severe liver damage, immunodepression, higher mortality rate, and lower LD50. No significant pharmacokinetic parameter changes were observed between the night and daytime treatment groups. These findings suggest the dosing-time dependent toxicity of clofarabine synchronizes with the circadian rhythm of mice, which might provide new therapeutic strategies in further clinical application.

Killing of Escherichia coli by Myxococcus xanthus in aqueous environments requires exopolysaccharide-dependent physical contact.

Nutrient or niche-based competition among bacteria is a widespread phenomenon in the natural environment. Such interspecies interactions are often mediated by secreted soluble factors and/or direct cell-cell contact. As ubiquitous soil bacteria, Myxococcus species are able to produce a variety of bioactive secondary metabolites to inhibit the growth of other competing bacterial species. Meanwhile, Myxococcus spp. also exhibit sophisticated predatory behavior, an extreme form of competition that is often stimulated by close contact with prey cells and largely depends on the availability of solid surfaces. Myxococcus spp. can also be isolated from aquatic environments. However, studies focusing on the interaction between Myxococcus and other bacteria in such environments are still limited. In this study, using the well-studied Myxococcus xanthus DK1622 and Escherichia coli as model interspecies interaction pair, we demonstrated that in an aqueous environment, M. xanthus was able to kill E. coli in a cell contact-dependent manner and that the observed contact-dependent killing required the formation of co-aggregates between M. xanthus and E. coli cells. Further analysis revealed that exopolysaccharide (EPS), type IV pilus, and lipopolysaccharide mutants of M. xanthus displayed various degrees of attenuation in E. coli killing, and it correlated well with the mutants' reduction in EPS production. In addition, M. xanthus showed differential binding ability to different bacteria, and bacterial strains unable to co-aggregate with M. xanthus can escape the killing, suggesting the specific nature of co-aggregation and the targeted killing of interacting bacteria. In conclusion, our results demonstrated EPS-mediated, contact-dependent killing of E. coli by M. xanthus, a strategy that might facilitate the survival of this ubiquitous bacterium in aquatic environments.

The clpB gene is involved in the stress response of Myxococcus xanthus during vegetative growth and development.

The Clp/HSP100 family of molecular chaperones is ubiquitous in both prokaryotes and eukaryotes. These proteins play important roles in refolding, disaggregating and degrading proteins damaged by stress. As a subclass of the Clp/HSP100 family, ClpB has been shown to be involved in various stress responses as well as other functions in bacteria. In the present study, we investigated the role of a predicted ClpB-encoding gene, MXAN5092, in the stress response during vegetative growth and development of Myxococcus xanthus. Transcriptional analysis confirmed induction of this clpB homologue under different stress conditions, and further phenotypic analysis revealed that an in-frame deletion mutant of MXAN5092 was more sensitive to various stress treatments than the wild-type strain during vegetative growth. Moreover, the absence of the MXAN5092 gene resulted in decreased heat tolerance of myxospores, indicating the involvement of this clpB homologue in the stress response during the development of myxospores. The M. xanthus recombinant ClpB (MXAN5092) protein also showed a general chaperone activity in vitro. Overall, our genetic and phenotypic analysis of the predicted ATP-dependent chaperone protein ClpB (MXAN5092) demonstrated that it functions as a chaperone protein and plays an important role in cellular stress tolerance during both vegetative growth and development of M. xanthus.

Why we need semisolid decalcification system in bone tissue engineering? A story begins with honeycomb.

The repair of large segmental bone defects remains a tough problem disturbing surgeons and researchers. Bone tissue engineering brings some new sight in this field. However, it has not been effectively applied in clinics, for the reason that the involved mechanism is not well understood. Thus, we need to know the osteogenesis process of the tissue-engineered bone including distribution, proliferation and interaction among seed cells pre-inoculated in biomaterials as well as the function of surrounding tissues. As a matter of fact, the tissue-engineered bone or the biomaterials are solid and opaque, which makes the study difficult. Here, inspired by the structure of honeycomb and amber, we hypothesize a semisolid decalcification protocol to solve this problem.

Comparison of the antioxidant activity amongst Gingko biloba extract and its main components.

OBJECTIVE: To compare the antioxidant activity amongst the extract of Ginkgo biloba (EGb) and its main components, flavonoids and terpenoids. METHODS: The induction of EGb, flavonoids and terpenoids on a typical antioxidant enzyme, glutamate cysteine ligase catalytic subunit (GCLC), in cell lines was detected by Western-blot. The effects of EGb, flavonoids and terpenoids on superoxide anion radical (O2*(-)), hydroxyl radical (OH*), rat erythrocyte hemolysis and lipid peroxidation of rat liver homogenate were determined by respective activity methods. RESULTS: EGb and flavonoids but not terpenoids were demonstrated significantly to induce the antioxidant enzyme (GCLC), directly scavenge O2*(-), OH* and inhibit rat erythrocyte hemolysis and lipid peroxidation of rat liver homogenate. Compared these antioxidant activities between EGb and flavonoids, the activities of flavonoids were weaker than those of EGb, which contains similar dose of flavonoids. CONCLUSION: EGb has stronger antioxidant activities than flavonoids, but terpenoids did not show antioxidant activity in this research.