Cancer-associated fibroblasts contributed to hepatocellular carcinoma recurrence and metastasis via CD36-mediated fatty-acid metabolic reprogramming.

Cancer-associated fibroblasts (CAFs) are the main components in the tumor microenvironment. Tumors activate fibroblasts from quiescent state into activated state by secreting cytokines, and activated CAFs may in turn promote tumor progression and metastasis. Therefore, studies targeting CAFs could enrich the therapeutic options for tumor treatment. In this study, we demonstrate that the content of lipid droplets and the expression of autophagosomes were higher in CAFs than in peri-tumor fibroblasts (PTFs), which was inhibited by 5-(tetradecyloxy)-2-furoic acid(TOFA). The expression of CD36 in CAFs was higher than that in PTFs at both mRNA and protein levels. Inhibition of CD36 activity using either the CD36 inhibitor SSO or siRNA had a significant negative impact on the proliferation and migration abilities of CAFs, which was associated with reduced levels of relevant activated genes (α-SMA, FAP, Vimentin) and cytokines (IL-6, TGF-ß and VEGF-α). SSO also inhibited HCC growth and tumorigenesis in nude mice orthotopically implanted with CAFs and HCC cells. Our data further show that CD36+CAFs affected the expression of PD-1 in CTLs leading to CTL exhaustion, and that patients with high CD36 expression in CAFs were correlated with shorter overall survival (OS). Together, our data demonstrate that CAFs were active in lipid metabolism with increased lipid content and lipophagy activity. CD36 may play a key role in the regulation of the biological behaviors of CAFs, which may influence the proliferation and migration of tumor cells by reprograming the lipid metabolism in tumor cells. Thus, CD36 could be an effective therapeutic target for the treatment of HCC.

Overexpression of COX7A1 Promotes the Resistance of Gastric Cancer to Oxaliplatin and Weakens the Efficacy of Immunotherapy.

Gastric cancer (GC) is one of the most common clinical malignant tumors worldwide, with high morbidity and mortality. Presently, the overall response rate to immunotherapy is low, and current methods for predicting the prognosis of GC are not optimal. Therefore, novel biomarkers with accuracy, efficiency, stability, performance ratio, and wide clinical application are needed. Based on public data sets, the chemotherapy cohort and immunotherapy cohort from Sun Yat-sen University Cancer Center, a series of bioinformatics analyses, such as differential expression analysis, survival analysis, drug sensitivity prediction, enrichment analysis, tumor immune dysfunction and exclusion analysis, single-sample gene set enrichment analysis, stemness index calculation, and immune cell infiltration analysis, were performed for screening and preliminary exploration. Immunohistochemical staining and in vitro experiments were performed for further verification. Overexpression of COX7A1 promoted the resistance of GC cells to Oxaliplatin. COX7A1 may induce immune escape by regulating the number of fibroblasts and their cellular communication with immune cells. In summary, measuring the expression levels of COX7A1 in the clinic may be useful in predicting the prognosis of GC patients, the degree of chemotherapy resistance, and the efficacy of immunotherapy.

Highly Curved Defect Sites: How Curvature Effect Influences Metal-Free Defective Carbon Electrocatalysts.

Topological defects are widely recognized as effective active sites toward a variety of electrochemical reactions. However, the role of defect curvature is still not fully understood. Herein, carbon nanomaterials with rich topological defect sites of tunable curvature is reported. The curved defective surface is realized by controlling the high-temperature pyrolytic shrinkage process of precursors. Theoretical calculations demonstrate bending the defect sites can change the local electronic structure, promote the charge transfer to key intermediates, and lower the energy barrier for oxygen reduction reaction (ORR). Experimental results convince structural superiority of highly-curved defective sites, with a high kinetic current density of 22.5 mA cm-2 at 0.8 V versus RHE for high-curvature defective carbon (HCDC), ≈18 times that of low-curvature defective carbon (LCDC). Further raising the defect densities in HCDC leads to the dual-regulated products (HCHDC), which exhibit exceptionally outstanding ORR activity in both alkaline and acidic media (half-wave potentials: 0.88 and 0.74 V), outperforming most of the reported metal-free carbon catalysts. This work uncovers the curvature-activity relationship in carbon defect for ORR and provides new guidance to design advanced catalysts via curvature-engineering.

Monocarboxylate transporter 4 inhibition potentiates hepatocellular carcinoma immunotherapy through enhancing T cell infiltration and immune attack.

BACKGROUND AND AIMS: Monocarboxylate transporter (MCT) 4 is a high-affinity lactate transporter that is primarily involved in the maintenance of intracellular pH homeostasis and highly expressed in different tumors. However, the role of MCT4 in modulating immune responses against HCC remains unknown. APPROACH AND RESULTS: In this study, we demonstrated that MCT4 was overexpressed in HCC, which was associated with poor prognosis in patients. Genetic or pharmacological inhibition of MCT4 using VB124 (a highly potent MCT4 inhibitor) suppressed HCC tumor growth in immunocompetent mice model by enhancing CD8 + T cell infiltration and cytotoxicity. Such improved immunotherapy response by MCT4 targeting was due to combined consequences characterized by the alleviated acidification of tumor microenvironment and elevated the chemokine (C-X-C motif) ligand (CXCL) 9/CXCL10 secretion induced by reactive oxygen species/NF-κB signaling pathway. Combining MCT4 inhibition improved the therapeutic benefit of anti-programmed cell death 1 immunotherapy in HCC and prolonged mice survival. Moreover, higher MCT4 expression was observed in tumor tissues from nonresponder patients with HCC receiving neoadjuvant therapy with toripalimab. CONCLUSIONS: Our results revealed that lactate exportation by MCT4 has a tumor-intrinsic function in generating an immunosuppressive HCC environment and demonstrated the proof of the concept of targeting MCT4 in tailoring HCC immunotherapeutic approaches.

Whole-exome sequencing-based mutational profiling of hepatocellular adenoma malignant transformation to hepatocellular carcinoma.

Hepatocellular adenoma (HCA) represents a rare benign hepatic neoplasm with potential for malignant transformation into hepatocellular carcinoma (HCC), yet the underlying mechanism remains elusive. In this study, we investigated the genomic landscape of this process to identify therapeutic strategies for blocking malignant transformation. Using micro-detection techniques, we obtained specimens of adenoma, cancerous neoplasm and adjacent normal liver from three patients undergoing hepatic resection surgery. Whole-exome sequencing (WES) was performed, and genomic interactions between HCA and HCC components within the same tumour were evaluated using somatic variant calling, copy number variation (CNV) analysis, clonality evaluation and mutational signature analysis. Our results revealed genomic heterogeneity among patient cases, yet within each sample, HCA and HCC tissues exhibited a similar mutational landscape, suggesting a high degree of homology. Using nonnegative matrix factorization and phylogenetic trees, we identified shared and distinct mutational characteristics and uncovering necessary pathways associated with HCA-HCC malignant transformation. Remarkably, we found that HCA and HCC shared a common monoclonal origin while displaying significant genetic diversity within HCA-HCC tumours, indicating fundamental genetic connections or evolutionary pathways between the two. Moreover, elevated immune therapy-related markers in these patients suggested heightened sensitivity to immune therapy, providing novel avenues for the treatment of hepatic malignancies. This study sheds light on the genetic mechanisms underlying HCA-HCC progression, offering potential targets for therapeutic intervention and highlighting the promise of immune-based therapies in managing hepatic malignancies.

Engineering Interfacial Pt─O─Ti Site at Atomic Step Defect for Efficient Hydrogen Evolution Catalysis.

The hydrogen evolution reaction (HER) activity of defect-stabilized low-Pt-loading catalysts is closely related with defect type in support materials, while the knowledge about the effect of higher-dimensional defects on the property and activity of trapped Pt atomic species is scarce. Herein, small size (5-10 nm) TiO2 nanoparticles with abundant surface step defects (one kind of line defect) are used to direct the uniform anchoring of Pt atomic clusters (Pt-ACs) via Pt─O─Ti linkage. The as-made low-Pt catalysts (Pt-ACs/S-TiO2 -NP) exhibit exceptional HER intrinsic activity due to the unique step-site Pi-O-Ti species, in which the mass activity and turnover frequency are as high as 21.46 A mg Pt -1 and 21.69 s-1 at the overpotential of 50 mV, both far beyond those of benchmark Pt/C catalysts and other Pt-ACs/TiO2 samples with less step sites. Spectroscopic measurements and theoretical calculations reveal that the step-defect-located Pt─O─Ti sites can simultaneously induce the charge transfer from TiO2 substrate to the trapped Pt-ACs and the downshift of d-band center, which helps the proton reduction to H* intermediates and the following hydrogen desorption process, thus improving the HER. The work provides a deep insight on the interactions between high-dimensional defect and well-dispersed atomic metal motifs for superior HER catalysis.

eHealth Literacy of Chinese Residents During the Coronavirus Disease 2019 Pandemic: A Cross-sectional Survey.

The Coronavirus Disease 2019 (COVID-19) pandemic has become a leading societal concern. eHealth literacy is important in the prevention and control of this pandemic. The purpose of this study is to identify eHealth literacy of Chinese residents about the COVID-19 pandemic and factors influencing eHealth literacy. A total of 15 694 individuals clicked on the link to the questionnaire, and 15 000 agreed to participate and completed the questionnaire for a response rate of 95.58%. Descriptive statistics, χ 2 test, and logistic regression analysis were conducted to analyze participants' level of eHealth literacy about COVID-19 and its influencing factors. The results showed 52.2% of participants had relatively lower eHealth literacy regarding COVID-19 (eHealth literacy score ≤ 48). The scores of the information judgment dimension (3.09 ± 0.71) and information utilization dimension (3.18 ± 0.67) of the eHealth literacy scale were relatively lower. The logistics regression showed that sex, age, education level, level of uncertainty, having people around the respondent diagnosed with COVID-19, relationship with family, and relationship with others were associated to eHealth literacy (χ 2 = 969.135, P < .001). The public's eHealth literacy about COVID-19 needs to be improved, especially the ability to judge and utilize online information. Close collaboration among global health agencies, governments, healthcare institutions, and media is needed to provide reliable online information to the public. Interventions to improve eHealth literacy should take into account and accentuate the importance of sex, age, educational background, level of uncertainty, exposure to disease, and social support.

A novel transcription factor, ScAIL1, modulates plant defense responses by targeting DELLA and regulating gibberellin and jasmonic acid signaling in sugarcane.

DELLA proteins are important repressors of gibberellin signaling, regulating plant development and defense responses through crosstalk with various phytohormones. Sugarcane ScGAI encodes a DELLA protein that regulates culm development. However, it is unclear which transcription factors mediate the transcription of ScGAI. Here, we identified two different ScGAI promoter sequences that cooperatively regulate ScGAI transcription. We also identified a nuclear-localized AP2 family transcription factor, ScAIL1, which inhibits the transcription of ScGAI by directly binding to two ScGAI promoters. ScAIL1 was expressed in all sugarcane tissues tested and was induced by gibberellin and various stressors, including NaCl, polyethylene glycol, and pathogenic fungi and bacteria. Overexpression of ScAIL1 in rice significantly improved resistance to bacterial blight and rice blast, while reducing growth and development. In addition, several genes associated with stress responses were significantly up-regulated in transgenic rice overexpressing ScAIL1. Endogenous phytohormone content and expression analysis further revealed that ScAIL1-overexpressing lines improved resistance to bacterial blight and rice blast instead of promoting growth, and that this response was associated with increased jasmonic acid synthesis and gibberellin inactivation. These results provide molecular evidence that the role of ScAIL1 in the plant defense response is related to jasmonic acid and gibberellin signaling.

Molecular pathways underlying tissue injuries in the bladder with ketamine cystitis.

Ketamine cystitis (KC) is a chronic bladder inflammation leading to urinary urgency, frequency, and pain. The pathogenesis of KC is complicated and involves multiple tissue injuries in the bladder. Recent studies indicated that urothelium disruption, lamina propria fibrosis and inflammation, microvascular injury, neuropathological alterations, and bladder smooth muscle (BSM) abnormalities all contribute to the pathogenesis of KC. Ketamine has been shown to induce these tissue injuries by regulating different signaling pathways. Ketamine can stimulate antiproliferative factor, adenosine triphosphate, and oxidative stress to disrupt urothelium. Lamina propria fibrosis and inflammation are associated with the activation of cyclooxygenase-2, nitric oxide synthase, immunoglobulin E, and transforming growth factor ß1. Ketamine contributes to microvascular injury via the N-methyl-D aspartic receptor (NMDAR), and multiple inflammatory and angiogenic factors such as tumor necrosis factor α and vascular endothelial growth factor. For BSM abnormalities, ketamine can depress the protein kinase B, extracellular signal-regulated kinase, Cav1.2, and muscarinic receptor signaling. Elevated purinergic signaling also plays a role in BSM abnormalities. In addition, ketamine affects neuropathological alterations in the bladder by regulating NMDAR- and brain-derived neurotrophic factor-dependent signaling. Inflammatory cells also contribute to neuropathological changes via the secretion of chemical mediators. Clarifying the role and function of these signaling underlying tissue injuries in the bladder with KC can contribute to a better understanding of the pathophysiology of this disease and to the design of effective treatments for KC.

Mifepristone combined with ethacridine lactate for third-trimester stillbirth induction: a 5-year experience from Shanghai.

OBJECTIVE: To review and analyze the efficacy and safety of mifepristone combined with ethacridine lactate for induction of stillbirth in the third trimester. METHODS: All patients with stillbirth in late pregnancy (≥ 28 weeks) in a university-affiliated maternity center from October 2016 to September 2021 were included in this study. After exclusion, patients were divided into ethacridine lactate and non-ethacridine lactate groups according to induction methods. Logistic regression was conducted to identify the risks of complications. RESULTS: We identified 122 patients that experienced stillbirth (5' Apgar score = 0) in third-trimester from the 5-year total deliveries in the hospital, among whom 39 stillbirths that resulted from termination of pregnancy for severe fetal anomalies and 1 stillbirth that was in twin pregnancy were excluded. Thus, 82 cases with stillbirths (dead before induction) were included in the analyses. In the 82 cases, 49 (59.76%) accepted intra-amniotic ethacridine lactate induction with 47 (95.92%, 47/49) successfully induced. No statistical difference was observed in induction failure rate between ethacridine dosage groups of < 75mg and ≥ 75mg (0/25, vs. 2/24, respectively; P > 0.05). The ethacridine lactate induction group showed no increased risks in complications (6.12%, 3/49), compared with non-ethacridine lactate group (12.12%, 4/33) (P = 0.35, OR, 0.47, 95%CI, 0.10 to 2.27). CONCLUSION: Mifepristone combined with ethacridine lactate is a safe and low-risk induction method for patients with stillbirth in the third trimester.

Comprehensive analysis of complement-associated molecular features in hepatocellular carcinoma.

The complement cascade plays a "complementing" role in human immunity. However, the potential roles of complement system in impacting molecular and clinical features of hepatocellular carcinoma (HCC) remain unclear. In this study, eleven public datasets are analyzed to compare the complement status between normal and cancerous samples based on 18 classical complement-associated genes. The complement scores are constructed to quantify complement signatures of individual tumors. HCC patients in the The Cancer Genome Atlas (TCGA) cohort are focused to perform systematical analyses between complement status and immune infiltration, miRNA expression, DNA methylation, clinicopathological features, and drug response. The results show that the complement scores in normal tissues are dramatically higher than those of tumor tissues. Tumor samples in the TCGA cohort are classified into complement score-low and score-high groups. Pathway analysis reveals that tumor-promoting pathways are typically inhibited in complement score-high group. This study also shows that tumor-killing immune cells, such as CD8 + T cells and natural killer cells are abundant and tumor-suppressing miRNAs are upregulated in complement score-high samples. In addition, we identify that complement scores are negatively correlated with certain clinical features, including pathological grade, clinical-stage, and portal vein invasion. Moreover, various molecular features together with complement scores are found to be correlated with response to anti-cancer drugs. This study provides a comprehensive and multidimensional analysis conducive to understanding the role of complement in cancer.

Cross-cultural validation and psychometric testing of the Debriefing Experience Scale (DES): a cross-sectional study.

BACKGROUND: The Debriefing Experience Scale (DES) is a tool that is used to explore nursing students' subjective experiences during a debriefing and to help determine best debriefing practices. A Chinese version of the scale has not been found; its development can enhance learning in simulation activites in Chinese healthcare education programs. METHODS: A simplified Chinese version of the DES was developed and tested using 34 Chinese undergraduate (second year) nursing students. They participated in six simulation scenarios and debriefings. Eight experts were consulted to determine the content validity of the scale. Critical ratio method, Cronbach's alpha, intraclass correlation coefficient, correlation coefficient and factor analysis were used in testing the psychometric properties of the scale. RESULTS: Analysis of 200 scales showed that the simplified Chinese version of the DES had good potential in discriminatiing Chinese nursing students' experiences of debriefing. CONCLUSIONS: The simplified Chinese DES was effective in evaluating the experience of debriefing. A larger sample size and multicenter research is needed to confirm these findings.

Relationship between eHealth literacy and psychological status during COVID-19 pandemic: A survey of Chinese residents.

AIMS: To investigate the eHealth literacy and the psychological status of Chinese residents during the COVID-19 pandemic and explore their interrelationship. BACKGROUND: The COVID-19 outbreak has placed intense psychological pressure on community residents. Their psychological status may be affected by eHealth literacy due to home isolation during this rampant pandemic. METHODS: This is a Web-based cross-sectional survey conducted on the JD Health platform, which resulted in 15,000 respondents having participated in this survey. The eHealth Literacy Questionnaire (EHLQ), Patient Health Questionnaire-9 (PHQ-9), Insomnia Severity Index (ISI) and Impact of Event Scale-Revised (IES-R) were used. The Pearson correlation was used to analyse the relationship between eHealth literacy and depression, insomnia and post-traumatic stress disorder. RESULTS: The score of eHealth literacy was 48.88 ± 8.46, and 11.4%, 6.8% and 20.1% of respondents experienced moderate to severe depression, insomnia and post-traumatic stress disorder. eHealth literacy negatively correlated with depression (r = -0.331), insomnia (r = -0.366) and post-traumatic stress disorder (r = -0.320). CONCLUSION: eHealth literacy is closely related to psychological status. Improving eHealth literacy may contribute to maintaining good psychological well-being. IMPLICATIONS FOR NURSING MANAGEMENT: It is necessary to strengthen the education of primary health care providers to enhance their ability to help community residents effectively use eHealth information.

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group.

Chemoselective sulfonylation and isonitrilation reactions for the divergent synthesis of valuable diarylmethyl sulfones and isonitrile diarylmethanes starting from easy-to-synthesize para-quinone methides (p-QMs) and commercially abundant p-toluenesulfonylmethyl isocyanide (TosMIC) by using respectively zinc iodide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as catalysts were developed. The distinguishing feature of this method is that TosMIC plays a dual role from the same substrates in the reaction: as a sulfonyl source or as an isonitrile source. The synthetic utility of this protocol was also demonstrated in the synthesis of difluoroalkylated diarylmethane 5 and diarylmethane ketone derivatives 6 and 7, which are important core structures in natural products and medicines.

Novel Compound-Target Interactions Prediction for the Herbal Formula Hua-Yu-Qiang-Shen-Tong-Bi-Fang.

Herbal formulae have a long history in clinical medicine in Asia. While the complexity of the formulae leads to the complex compound-target interactions and the resultant multi-target therapeutic effects, it is difficult to elucidate the molecular/therapeutic mechanism of action for the many formulae. For example, the Hua-Yu-Qiang-Shen-Tong-Bi-Fang (TBF), an herbal formula of Chinese medicine, has been used for treating rheumatoid arthritis. However, the target information of a great number of compounds from the TBF formula is missing. In this study, we predicted the targets of the compounds from the TBF formula via network analysis and in silico computing. Initially, the information of the phytochemicals contained in the plants of the herbal formula was collected, and subsequently computed to their corresponding fingerprints for the sake of structural similarity calculation. Then a compound structural similarity network infused with available target information was constructed. Five local similarity indices were used and compared for their performance on predicting the potential new targets of the compounds. Finally, the Preferential Attachment Index was selected for it having an area under curve (AUC) of 0.886, which outperforms the other four algorithms in predicting the compound-target interactions. This method could provide a promising direction for identifying the compound-target interactions of herbal formulae in silico.

[Cluster analysis of Dendrobium officinale from different populations through agronomy characterization].

Through resources investigation and sample collection,a total number of 392 Dendrobium officinale from 38 different populations,9 provinces were processed for measuring and observing.Fourteen agronomy characterizations like stem height,stem diameter,number of node in stem were selected for further classification.The cluster analysis was performed using Ward and Euclidean method.The results showed that the threshold of genetic distance was 2.77.Thirtyeight populations were divided into 6 groups.The factor analysis showed that,the leaf shape,stem shape,pitch length and leaf color were very important factors for classification.This study establish the foundation for analyzing the genetic relationship of D.officinale from different populations.

Effects of Glycyrrhizin in a Mouse Model of Lung Adenocarcinoma.

BACKGROUND: Currently, there is a global attempt to identify potential anti-cancer agents with low toxicity. Previous studies have found that glycyrrhizin exerts anti-cancer action with low toxicity through suppressing thromboxane A2 (TxA2) in lung cancer cell lines. However, these effects have not yet been determined in animal models of lung cancer. METHODS: Human lung adenocarcinoma xenografts were established in nude mice by the introduction of A549 cells with stable transfection of the TxA2 receptor (TPα). The animal model was confirmed by the hematoxylin and eosin (H&E) method. Tumor-bearing mice were then administered graded concentrations of glycyrrhizin, cisplatin or both. After the treatments, body weights of all animals were recorded, and immunohistochemistry staining of lung tissues and serum biochemistry detection of aspartate amino transferase (AST), alanine amino transferase (ALT), urea and creatinine were carried out. RESULTS: Treatment with glycyrrhizin alone or the combination of cisplatin and glycyrrhizin profoundly reduced expression of thromboxane synthase (TxAS) as well as proliferating cell nuclear antigen (PCNA), recovered the body weight, and rescued damage of liver and kidney in tumor-bearing mice. Although it inhibited PCNA expression, cisplatin could not significantly suppress TxAS expression. Because of a positive feedback loop between TPα and TxAS, the effects of glycyrrhizin are possibly attributable to the suppression of the TxA2 pathway. CONCLUSIONS: This study provides in vivo evidence to support glycyrrhizin as a potential candidate for developing new regimens to overcome tumor progression and the resistance and toxicity of cisplatin.

Buyang Huanwu decoction facilitates neurorehabilitation through an improvement of synaptic plasticity in cerebral ischemic rats.

BACKGROUND: Loss of neural function is a critical but unsolved issue after cerebral ischemia insult. Neuronal plasticity and remodeling are crucial for recovery of neural functions after brain injury. Buyang Huanwu decoction, which is a classic formula in traditional Chinese medicine, can positively alter synaptic plasticity. This study assessed the effects of Buyang Huanwu decoction in combination with physical exercise on neuronal plasticity in cerebral ischemic rats. METHODS: Cerebral ischemic rats were administered Buyang Huanwu decoction and participated in physical exercise after the induction of a permanent middle cerebral artery occlusion. The neurobehavioral functions and infarct volumes were evaluated. The presynaptic (SYN), postsynaptic (GAP-43) and cytoskeletal (MAP-2) proteins in the coronal brain samples were evaluated by immunohistochemistry and western blot analyses. The ultrastructure of the neuronal synaptic junctions in the same region were analyzed using transmission electron microscopy. RESULTS: Combination treatment of Buyang Huanwu decoction and physical exercise ameliorated the neurobehavioral deficits (p < 0.05), significantly enhanced the expression levels of SYN, GAP-43 and MAP-2 (p < 0.05), and maintained the synaptic ultrastructure. CONCLUSIONS: Buyang Huanwu decoction facilitated neurorehabilitation following a cerebral ischemia insult through an improvement in synaptic plasticity. Graphical abstract The Buyang Huanwu decoction (BYHWD) combined with physical exercise (PE) attenuates synaptic disruption and promotes synaptic plasticity following cerebral ischemia (stroke).

The Fabrication and Characterization of Ni/4H-SiC Schottky Diode Radiation Detectors with a Sensitive Area of up to 4 cm².

Silicon carbide (SiC) detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1-4 cm² were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response to alpha particles ranging from 5.157 to 5.805 MeV was obtained. The detectors were proved to have a low dark current, a good energy resolution, and a high neutron/gamma discrimination for pulsed radiation, showing the advantages in charged particle detection and neutron detection in high-temperature and high-radiation environments.

[Regulation of pyocyanin biosynthesis by transcriptional factor sigma38 in Pseudomonas aeruginosa PAO1].

Pyocyanin, an important virulence factor, is synthesized and secreted by Pseudomonas aeruginosa PAO1and plays a critical role in pathogen-host interaction during infection. Sigma38 (σ38, σS) is a central regulator for many virulence production in pathogens. Objective: Our aim is to identify expression and regulation of two phenazine-producing operons mediated by the sigma38 factor in Pseudomonas aeruginosa PAO1. Methods: We first cloned the flanking fragments of rpoS from the chromosomal DNA of P. aeruginosa PAO1 and constructed the deletion mutant ΔrpoS with the insertion of gentamycin resistance cassette (aacC1). Complementation of rpoS was then carried out after construction and introduction of pME10S (containing the whole rpoS region). Finally, we created the mutant ΔrpoSphz1 and ΔrpoSphz2, and measured pyocyanin production by these mutants in GA medium, using the parental strain Δphz1 and Δphz2 as controls. Results: In GA medium, pyocyanin production by mutant ΔrpoS increased dramatically in comparison with the wild-type strain PAO1. Production of pyocyanin, however, was decreased to the level of the wild-type strain with complementation of the derivative ΔrpoS harboring pME10S. Mutant ΔrpoSphz2 produced much more pyocyanin than mutant Δphz2. Mutant ΔrpoSphz1, however, produced much less pyocyanin than mutant Δphz1. Conclusion: By positively regulating the expression of phz2 and negatively regulating the phz1, sigma38 factor exerts negative modulation on pyocyanin biosynthesis in P. aeruginosa PAO1.