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We have previously shown that exposure to TiO2 nanoparticles (NPs) reduces the resistance of HeLa cells to bacterial infection. Here we demonstrate that the increased infectivity is associated with enhanced asymmetry in the cholesterol distribution. We applied a live cell imaging method which uses tunable orthogonal cholesterol sensors to visualize and quantify in-situ cholesterol distribution between the two leaflets of the plasma membrane (PM). In the control culture, we found marked transbilayer asymmetry of cholesterol, with the concentration in the outer plasma membrane (OPM) being 13 ± 2-fold higher than that in the inner plasma membrane (IPM). Exposure of the culture to 0.1 mg/mL of rutile TiO2 NPs increased the asymmetry such that the concentration in the OPM was 51 ± 10 times higher, while the total cholesterol content increased only 21 ± 2%. This change in cholesterol gradient may explain the increase in bacterial infectivity in HeLa cells exposed to TiO2 NPs since many pathogens, including Staphylococcus aureus used in the present study, require cholesterol for proper membrane attachment and virulence. RT-PCR indicated that exposure to TiO2 was responsible for upregulation of the ABCA1 and ABCG1 mRNAs, which are responsible for the production of the cholesterol transporter proteins that facilitate cholesterol transport across cellular membranes. This was confirmed by the observation of an overall decrease in bacterial infection in ABCA1 knockout or methyl-β-cyclodextrin-treated HeLa cells, as regardless of TiO2 NP exposure. Hence rather than preventing bacterial infection, TiO2 nanoparticles upregulate genes associated with membrane cholesterol production and distribution, hence increasing infectivity. Statement of significance A great deal of work has been done regarding the toxicology of the particles, especially focusing on detrimental outcomes associated with reactive oxygen species (ROS) production. In this paper we show unambiguously a very surprising result, namely the ability of these particles to enhance bacterial infection even at very small exposure levels, where none of the deleterious effects of ROS products can yet be detected. Using a new imaging technique, we are able to demonstrate, in operando, the effect of the particles on cholesterol generation and distribution in live HeLa cells. This paper also represents the first in a series where we explore other consequences of increased membrane cholesterol, due to particle exposure, which are known to have multiple other consequences on human tissue function and development.

We proposed a method to regulate nucleic acid polymerization by proximity and designed an ultrasensitive biosensor based on proximity-induced exponential amplification reaction for proximity assay of proteins (streptavidin) and small molecules (adenosine triphosphate), which allows us to detect a variety of interesting targets by simply changing the binding sites of DNA.

Viral diseases pose a major risk to human health and human society. Research on vaccines as an economical and effective countermeasure is of great importance to prevent the spread of viruses and to treat viral diseases. Here in this work, we first introduce the reader to the role of the immune system in which vaccines are involved, while reviewing the history of vaccine development. We then present a detailed classification of viral vaccines, describing representative applications to elucidate the research value of different vaccines. We conclude with our views on future trends in the development of vaccine designs.

The activation and cleavage of C–C bonds remains a critical scientific issue in many organic reactions and is an unmet challenge due to their intrinsic inertness and ubiquity. Meanwhile, it is crucial for the valorization of lignin into high-value chemicals. Here, we proposed a novel strategy to enhance the Caromatic–Cα bond cleavage by pre-functionalization with amine sources, in which an active amine intermediate is first formed through Markovnikov hydroamination to reduce the dissociation energy of the Caromatic–Cα bond which is then cleaved to form target chemicals. More importantly, this strategy provides a method to achieve the maximum utilization of the aromatic nucleus and side chains in lignin or its platform molecules. Phenols and N,N-dimethylethylamine compounds with high yields were produced from herbaceous lignin or the p-coumaric acid monomer in the presence of industrially available dimethylamine (DMA).

Vagus nerve stimulation (VNS) restores autonomic balance, suppresses inflammation action and minimizes cardiomyocyte injury. However, little knowledge is known about the VNS’ role in cardiomyocyte phenotype, sarcomere organization, and energy metabolism of infarcted hearts. VNS in vivo and acetylcholine (ACh) in vitro optimized the levels of α/β-MHC and α-Actinin positive sarcomere organization in cardiomyocytes while reducing F-actin assembly of cardiomyocytes. Consistently, ACh improved glucose uptake while decreasing lipid deposition in myocytes, correlating both with the increase of Glut4 and CPT1α and the decrease of PDK4 in infarcted hearts in vivo and myocytes in vitro, attributing to improvement in both glycolysis by VEGF-A and lipid uptake by VEGF-B in response to Ach. This led to increased ATP levels accompanied by the repaired mitochondrial function and the decreased oxygen consumption. Functionally, VNS improved the left ventricular performance. In contrast, ACh-m/nAChR inhibitor or knockdown of VEGF-A/B by shRNA powerfully abrogated these effects mediated by VNS. On mechanism, ACh decreased the levels of nuclear translocation of FoxO3A in myocytes due to phosphorylation of FoxO3A by activating AKT. FoxO3A overexpression or knockdown could reverse the specific effects of ACh on the expression of VEGF-A/B, α/β-MHC, Glut4, and CPT1α, sarcomere organization, glucose uptake and ATP production. Taken together, VNS optimized cardiomyocytes sarcomere organization and energy metabolism to improve heart function of the infarcted heart during the process of delaying and/or blocking the switch from compensated hypertrophy to decompensated heart failure, which were associated with activation of both P13K/AKT-FoxO3A-VEGF-A/B signaling cascade.

Development of high-performance catalysts for carbon dioxide (CO2) hydrogenation is crucial for CO2 utilization. Herein, a heterogeneous catalyst for CO2 hydrogenation to formate was developed by c...

Uncovering the mechanisms of virus infection and assembly is crucial for preventing the spread of viruses and treating viral disease. The technique of single-virus tracking (SVT), also known as single-virus tracing, allows one to follow individual viruses at different parts of their life cycle and thereby provides dynamic insights into fundamental processes of viruses occurring in live cells. SVT is typically based on fluorescence imaging and reveals insights into previously unreported infection mechanisms. In this review article, we provide the readers a broad overview of the SVT technique. We first summarize recent advances in SVT, from the choice of fluorescent labels and labeling strategies to imaging implementation and analytical methodologies. We then describe representative applications in detail to elucidate how SVT serves as a valuable tool in virological research. Finally, we present our perspectives regarding the future possibilities and challenges of SVT.

Introduction: Gastrointestinal stromal tumor (GIST) is among the leading malignancies of the digestive system. GIST is not susceptible to chemotherapies and is prone to recurrence or metastasis after surgical operation. Secoisolariciresinol diglucoside (SDG) was suggested to have potential anticancer effects, but no clinical evidence had been available. Here we report successful treatment of a postoperative GIST case with dietary SDG. Presentation of Case: The patient was a 58-year-old man. He had GIST and received resection of small intestinal lesions 1 year before. He was diagnosed with postoperation of GIST and presented with high level of serum carbohydrate antigen 72-4 (CA72-4). The patient was then treated with dietary administration of SDG with his voluntary acceptance for 5 months, and underwent 2 serum CA72-4 measurements during this period. CA72-4 level of the patient was restored to normal range after treatment with dietary SDG for 1 month. There was no aberrant CA72-4 level, recurrence or metastasis after the treatment with dietary SDG. Discussion: This is to our knowledge the first report on application of dietary SDG on a postoperative GIST patient with aberrant level of serum CA72-4. SDG can be transformed into active substances with antitumor effects by human gut bacteria. Dietary SDG might inhibit tumorigenicity and malignant behavior of GIST cells. Conclusion: The excellent effects suggest dietary SDG to be a potential therapy for GIST, especially against recurrence or metastasis.

Selective oxidation of ethers to lactones with O2 as a benign oxidant using Au/CeO2 as the catalyst has been developed. The oxygen vacancies and Au0 species on the surface of CeO2 contribute to the activation of O2. The excellent selectivity of lactones is due to the adsorption of ethers and activation of the C(sp3)–H bond on Au/CeO2.

Extracellular vesicles (EVs) are intercellular communicators that are heavily implicated in diverse pathological processes. However, it is poorly understood how EVs interact with recipient cells due to the lack of appropriate tracking techniques. Here, we report a robust chemoenzymatic labeling technique for visualizing the internalization process of EVs into target cells in real time. This method uses phospholipase D (PLD) to catalyze the in situ exchange of choline by alkyne in the native EV phosphatidylcholine. Subsequent alkyne-azide click chemistry allows conjugation of Cy5 dyes for visualizing EVs internalization by confocal fluorescence microscopy. The fluorescent labeling of EVs was accomplished in an efficient and biocompatible way, without affecting both the morphology and biological activity of EVs. We applied this chemoenzymatic labeling strategy to monitor the cellular uptake of cancer cell-derived EVs in real time and to further reveal multiple internalization mechanisms. This robust, biocompatible labeling strategy provides an essential tool for EV-related studies ranging from chemical biology to drug delivery.

Selective hydrodeoxygenation of biomass-derived aromatic alcohols to value-added chemical or fuel is of great importance for sustainable biomass upgrading, and hydrodeoxygenation of 5-hydroxymethylfurfural (HMF) to 2,5-dimethylfuran (DMF) is one of the most attractive reactions. Achieving the conversion of HMF to DMF using H2 at ambient temperature is challenging. In this work, we used PdCu nanoalloys to catalyze the selective hydrodeoxygenation reaction of HMF to DMF using H2 as the reducing agent. The reaction path and the product selectivity are governed by the crystallographic phase of the PdCu nanoalloys. It was discovered that body-centered cubic (BCC) PdCu nanoalloys supported on activated carbon (AC) exhibited outstanding performance with 93.6% yield of DMF at room temperature (PdCu/AC-BCC). A combination of experimental and density functional theory (DFT) studies showed that the tilted adsorption modes of furanic intermediates on PdCu-BCC nanoalloy surfaces accounted for the high selectivity of DMF; however, furan ring was activated on PdCu face-centered cubic (FCC) nanoalloy surfaces. Furthermore, PdCu/AC-BCC could also catalyze the hydrodeoxygenation of other aromatic alcohols at room temperature while maintaining the aromatic structures. This work opens the way for selective hydrodeoxygenation of the aromatic alcohols at room temperature with the aromatic ring intact., Graphical abstract, Public summary • Selectively cleaving of C–O bonds in lignocellulosic biomass is very difficult. The PdCu nanoalloys can catalyze the selective hydrodeoxygenation reaction of HMF to DMF • The PdCu nanoalloys with specific crystallographic phases can improve the selectivity of hydrodeoxygenation reaction • The body-centered cubic (BCC) PdCu nanoalloys exhibited outstanding performance with 93.6% yield of DMF at room temperature • PdCu/AC-BCC could also catalyze other aromatic alcohols at room temperature

Many enveloped viruses utilize endocytic pathways and vesicle trafficking to infect host cells, where the acidification of virus-containing endosomes triggers the virus-endosome fusion events. Therefore, simultaneous correlation of intracellular location, local pH, and individual virus dynamics is important for gaining insight into viral infection mechanisms. Here, an imaging approach is developed for spatiotemporal quantification of endosomal acidification on the viral journey in host cells using a fluorescence resonance energy transfer based ratiometric pH sensor consisting of a photostable and high-brightness QD, pH-sensitive fluorescent dyes, and virus-binding proteins. Ratiometric analysis of sensor-based single-virus tracking data enables to dissect a two-step endosomal acidification process during the infection of influenza viruses and elucidates the occurrence of the fission and sorting of virus-containing endosomes to recycling endosomes after initial acidification. This technique should serve as a robust approach for in situ quantification of endosomal acidification on the viral journey.

Supplemental Digital Content is available in the text, Objective: The current study aimed to understand epidemiological feature and critical factors associated with pathogenesis of circulating recombinant form (CRF) 01_AE strains in Northeast China. Design: Compared analysis was made between CRF01_AE and non-CRF01_AE samples to understand the pathogenicity features of CRF01_AE. Further analyses between CRF01_AE samples with high or low CD4+ cell counts and between samples with different coreceptor usages were done to explore the possible factors correlating to the pathogenesis of CRF01_AE viruses. Methods: The genotypes of newly identified strains were determined by phylogenetic analyses using Mega 6.06. Coreceptor usage was predicted by Geno2Pheno algorithm. Potential N-linked glycosylation site (PNGS) number was calculated using the online N-glycosite software. The properties of amino acid sequences were analyzed by the online ProtParam tool. Results: CRF01_AE become the main HIV-1 genotype since 2010. Compared with non-CRF01_AE group, the CRF01_AE group showed a higher proportion of samples with CD4+ cell count less than 200 cells/μl. Shorter amino acid length, fewer PNGSs and the presence of a basic motif R/KNXT or NR/KT in V4 correlated to a lower CD4+ cell count, and existence or coexistence of Thr12, Arg13, Val21 and Lys33, presence of more than 4 of net charges and lack of the PNGS within V3 favored to the X4/R5X4 coreceptor usage of CRF01_AE viruses. Conclusion: CRF01_AE has dominated HIV-1 genotype in Northeast China. Infection with CRF01_AE exhibited a fast disease progression, which may be associated with specific amino acid residues and PNGSs in V3 and V4 regions as well as amino acid length of V4 region.

Background Sterol-regulatory element binding protein 1 (SREBP1), an intracellular cholesterol sensor located in the endoplasmic reticulum, regulates the intracellular cholesterol by the Insig-Srebp-Scap pathway. Over-expression of SREBP1 can cause dyslipidemia. SREBP1 can regulate the metabolic pathway, and then promote the proliferation of tumor cells. However, there is no relevant research of metastasis and invasion in the field of colorectal cancer (CRC). Methods Expression of SREBP1 was manipulated in CRC cell lines with low and high level SREBP1 expression by transfectiong with plasmids containing the SREBP1 gene, or by shRNA. The effect of SREBP1 on cell migration was assayed. The expression of SREBP1, p65 and MMP7 were detected by western blot. Human umbilical vein endothelial cell was used for detection of angiogenesis by adding the culture supernatant from HT29 and SW620. The level of reactive oxygen species (ROS) was detected by Dihydroethidium (DHE) staining. NF-κB inhibitor SN50 was used to test the relationship of SREBP1, NF-κB pathway and MMP7. Results We found that the expression of SREBP1 in colon adenocarcinoma was significantly higher than that in noncancerous tissues, especially in the invasive tumor front including tumor budding. In vitro, SREBP1 over-expressed in colon cancer cell lines HT29 promoted angiogenesis in endothelial cells, increased ROS levels, phosphorylation of NF-κB-p65 and increases MMP7 expression. The effect of SREBP1 on expression of MMP7 was lost following treatment with the NF-κB inhibitor SN50. Conclusion Our results suggest that SREBP1 can promote the invasion and metastasis of CRC cells by means of promoting the expression of MMP7 related to phosphorylation of p65. Electronic supplementary material The online version of this article (10.1186/s12885-019-5904-x) contains supplementary material, which is available to authorized users.

Live cells, as reservoirs of biochemical reactions, can serve as amazing integrated chemical plants where precursor formation, nucleation and growth of nanocrystals, and functional assembly, can be carried out accurately following an artificial program. It is crucial but challenging to deliberately direct intracellular pathways to synthesize desired nanocrystals that cannot be produced naturally in cells, because the relevant reactions exist in different spatiotemporal dimensions and will never encounter each other spontaneously. This article summarizes the progress in the introduction of inorganic functional nanocrystals into live cells via the ‘artificially regulated space–time-coupled live-cell synthesis’ strategy. We also describe ingenious bio-applications of nanocrystal–cell systems, and quasi-biosynthesis strategies expanded from live-cell synthesis. Artificially regulated live-cell synthesis—which involves the interdisciplinary application of biology, chemistry, nanoscience and medicine—will enable researchers to better exploit the unanticipated potentialities of live cells and open up new directions in synthetic biology.

Cholesterol is an essential component of the mammalian plasma membrane involved in diverse cellular processes. Our recent quantitative imaging analysis using ratiometric cholesterol sensors showed that the available cholesterol concentration in the inner leaflet of the plasma membrane (IPM) is low in unstimulated cells and increased in a stimulus-specific manner to trigger cell signaling events. However, the transbilayer distribution of cholesterol in the plasma membrane of mammalian cells remains controversial. Here we report a systematic and rigorous evaluation of basal IPM cholesterol levels in a wide range of mammalian cells with different properties employing cholesterol sensors derived from the D4 domain of the Perfringolysin O toxin and a sterol-transfer protein, Osh4. Results consistently showed that, although basal IPM cholesterol levels vary significantly among cells, they remain significantly lower than cholesterol levels in the outer leaflets. We found that IPM cholesterol levels were particularly low in all tested primary cells. These results support the universality of the low basal IPM cholesterol concentration under physiological conditions. We also report here the presence of sequestered IPM cholesterol pools, which may become available to cytosolic proteins under certain physiological conditions. We hypothesize that these pools may partly account for the low basal level of available IPM cholesterol. In conclusion, we provide new experimental data that confirm the asymmetric transbilayer distribution of the plasma membrane cholesterol, which may contribute to regulation of various cellular signaling processes at the plasma membrane.

We have previously shown that exposure to TiO2 nanoparticles (NPs) reduces the resistance of HeLa cells to bacterial infection. Here we demonstrate that the increased infectivity is associated with enhanced asymmetry in the cholesterol distribution. We applied a new live cell imaging method which uses tunable orthogonal cholesterol sensors to visualize and quantify in-situ cholesterol distribution between the two leaflets of the plasma membrane (PM). In the control culture, we found marked transbilayer asymmetry of cholesterol, with the concentration in the outer plasma membrane (OPM) being 12.5(2.2)-fold higher than that in the inner plasma membrane (IPM). Exposure of the culture to 0.1 mg/mL of rutile TiO2 NPs increased the asymmetry such that the concentration in the OPM was 50.8(9.5) times higher, while the total cholesterol content increased only 20.5(2.4)%. This change in cholesterol gradient may explain the increase in bacterial infectivity in HeLa cells exposed to TiO2 NPs since many pathogens, including Staphylococcus aureus used in the present study, require cholesterol for proper membrane attachment and virulence. RT-PCR indicated that exposure to TiO2 was responsible for upregulation of the ABCA1 and ABCG1 mRNAs, which are responsible for the production of the cholesterol transporter proteins that facilitate cholesterol transport across cellular membranes. This was confirmed by the observation of an overall decrease in bacterial infection in ABCA1 knockout or methyl-β-cyclodextrin-treated HeLa cells, as regardless of TiO2 NP exposure. Hence rather than preventing bacterial infection, TiO2 nanoparticles upregulate genes associated with membrane cholesterol production and distribution, hence increasing infectivity.

This paper studies the optimization of ultrasonic-assisted extraction of polysaccharides from Oenothera biennis L. leaves using Box-Behnken design, and their in vitro antioxidant activity and structure. It is demonstrated that the optimum extraction conditions are: the ultrasonic power at 400 W, solvent-tosample ratio of 23:1 (mL/g), ultrasonication temperature at 53 °C, and time for 36 min, under which the yield of polysaccharides from Oenothera biennis L. leaves, namely 3.54%, remains close to the predicted value in the model. The assays of the scavenging effect on DPPH and hydroxyl free radicals, and of the reducing power indicate that polysaccharides from Oenothera biennis L. leaves possess strong antioxidant activity and certain relationship exists between their dose and effect in the concentration range of the experiment; Fourier IR spectroscopy reveals that characteristic absorption peak of polysaccharides can be seen from the sample; the DE-52 cellulose column chromatography, HPLC profiles, and GC-MS chromatogram identify the obtained OCP-2 as heteropolysaccharides, whose major components, including arabinose, mannose, galactose, and talose, have an average molecular weight of 5435 Da.

Ovarian cancer is the third most common cancer in the female reproductive organs and epithelial ovarian cancer has the highest lethality of all gynecological cancers. Pomegranate fruit juice (PFJ) has been shown to inhibit the growth of several types of cancer other than ovarian cancer. In this study, we exposed the ovarian cancer cell line A2780 to PFJ and two of its components (ellagic acid and luteolin). MTT and wound healing assays demonstrated that all three treatments suppressed the proliferation and migration of the ovarian cancer cells. In addition, western blotting and ELISA assays showed that the expression levels of MMP2 and MMP9 gradually decreased after treatment with increasing concentrations of ellagic acid and luteolin. To confirm our findings in the in vitro experiments, we used another ovarian cancer cell line, ES-2, in nude mice experiments. All three treatments inhibited tumor growth without obvious side-effects. Furthermore, compared with the control group, the expression levels of MMP2 and MMP9 were depressed. Ellagic acid induced a greater effect than luteolin, suggesting that ellagic acid might be a promising candidate for further preclinical testing for treatment of human ovarian cancer.

The influence of W content upon corrosion of Ni-xW-6Cr alloys in molten FLiNaK salts at 850 °C was examined. The results indicate a significantly greater depletion of Cr and W from Ni-xW-6Cr alloys with higher W contents in the molten FLiNaK salt, which mainly results from the increasing activities of W and Cr in the alloy with the W content increasing. The high concentrations of oxygen, Ni and Fe impurities further accelerate the corrosion of W and Cr from the alloy by providing more corrosion vacancies as diffusion paths in the alloy's near surface area.

In this work, an approach to improve the oxidation resistance of a Ni-based alloy was proposed by doping a high valence metal element into the oxides. Oxidation kinetics of Ni-28W-6Cr alloys with 0−0.2 wt.% Zr at 850 °C show that Zr can significantly decrease the oxidation rate of the alloy and the thickness of the inner oxide. Zr charged +4 prefers to segregate in the inner NiWO4 by replacing Ni2+, which inhibits the formation of oxygen vacancies and reduces the oxygen diffusion pathways, improving the oxidation resistance of the alloy.

Secoisolariciresinol (SECO) is a lignan of potential therapeutic value for diseases such as cancer, but its use has been limited by the lack of ideal production methods, even though its precursors are abundant in plants, such as flaxseeds. Here, we report the characterization of a bacterial strain, S1, isolated from the human intestinal flora, which could produce secoisolariciresinol by biotransformation of precursors in defatted flaxseeds. This bacterium was a Gram-negative and facultatively anaerobic straight rod without capsules. Biochemical assays showed that it was negative for production of oxidase, lysine decarboxylase, ornithine decarboxylase, arginine dihydrolase, and β-glucolase. The G + C content of genomic DNA was 57.37 mol%. Phylogenetic analysis by 16S rRNA and rpoB gene sequences demonstrated S1’s close relatedness to Klebsiella. No homologues were found for wzb or wzc (capsular genes), which may explain why Klebsiella sp. strain S1 does not have the capsule and was isolated from a healthy human individual. Based on the percentages of homologous genes with identical nucleotide sequences between the bacteria in comparison, we found that clear-cut genetic boundaries had been formed between S1 and any other Klebsiella strains compared, dividing them into distinct phylogenetic lineages. This work demonstrates that the intestinal Klebsiella, well known as important opportunistic pathogens prevalent in potentially fatal nosocomial infections, may contain lineages that are particularly beneficial to the human health.

Arterial stiffening is a consequence of aging and a cholesterol-independent risk factor for cardiovascular disease (CVD). Arterial stiffening and CVD show a sex bias, with men more susceptible than premenopausal women. How arterial stiffness and sex interact at a molecular level to confer risk of CVD is not well understood. Here, we used the sexual dimorphism in LDLR-null mice to show that the protective effect of female sex on atherosclerosis is linked to reduced aortic stiffness and reduced expression of matrix metalloproteinase-12 (MMP12) by lesional macrophages. Deletion of MMP12 in LDLR-null mice attenuated the male sex bias for both arterial stiffness and atherosclerosis, and these effects occurred despite high serum cholesterol. Mechanistically, we found that oxidized LDL stimulates secretion of MMP12 in human as well as mouse macrophages. Estrogen antagonizes this effect by downregulating MMP12 expression. Our data support cholesterol-independent causal relationships between estrogen, oxidized LDL–induced secretion of macrophage MMP12, and arterial stiffness that protect against atherosclerosis in females and emphasize that reduced MMP12 functionality can confer atheroprotection to males.

The effect of metallic impurities on corrosion of a Ni-26W-6Cr alloy in molten FLiNaK salts at 850 °C was investigated. Results show that the Ni-26W-6Cr alloy exhibits the same excellent compatibility with fluoride salts as Hastelloy N alloy. Fe impurities in molten salts accelerate the diffusion of Cr in the alloy, which determines the corrosion degree of the alloy. Unexpected depletion of W from the alloy was observed, which mostly results from the presence of Mo impurity in the salts. Mo impurity should be limited because of the significant effect of W on the neutron spectra of reactors.

The accurate and rapid determination of hydrogen peroxide (H2O2) levels is of great significance because of the far-ranging impacts of H2O2 homeostasis on human health. In this work, we developed an enhanced electrochemiluminescence (ECL) biosensor based on CdZnSeS quantum dots (QDs) condensed with ordered mesoporous carbon (OMC) for high-sensitive detection of H2O2 in live cells. Benefiting from the combination of QDs with the highly conductive OMC materials, the prepared ECL biosensor exhibited outstanding ECL signal. We then assessed the analytical performance of the ECL biosensor for H2O2 detection, and found that the biosensor possessed low detection limit, wide linear range, desirable selectivity, and long-time stability. By the detection of H2O2 in different live cells, the ECL biosensor platform shows its potential for reliable and sensitive H2O2 detection in diagnostic applications and physiological research.

Program of International ST National Natural Science Foundation of China [51371188, 51501216]; Strategic Priority Research Program of the Chinese Academy of Sciences [XDA02004210]

Background Epithelial carcinoma is a subtype of ovarian cancers, with the highest lethality among all ovarian cancer subtypes. Hitherto surgical excision combined with chemotherapy has been the most extensively employed method in clinical treatment. However, the disease relapses very frequently, calling for more effective therapies. Mangiferin, a natural xanthone glucoside, has displayed promising anti-cancer activities by in vitro studies, but its therapeutic value in epithelial ovarian cancer treatment, either by in vivo or in vitro studies, remained to be known. Purpose This study aimed to determine the suppressive activities of mangiferin on human epithelial ovarian cancer and elucidate the underlying molecular mechanisms. Study design and methods We employed the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the crystal violet assay to determine the half maximal inhibitory concentration (IC50) values of mangiferin with paclitaxel as a positive control and the inhibitory effects of mangiferin on the proliferation of two human epithelial ovarian cancer cell lines. Wound healing and Transwell assays were used to determine anti-metastastic activities of mangiferin. ES-2 xenograft nude mouse model was used for the in vivo experiments. Western blotting, enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry (IHC) assays were carried out for evaluating the expression level of matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9). Results In the present study, we demonstrated by both in vitro and in vivo assays that mangiferin suppressed the progress of epithelial ovarian cancer in a dose-dependent manner. In the animals treated with mangiferin, the tumor volume and weight were reduced significantly. Analyses of involved molecular events demonstrated that mangiferin down-regulated the expression of metastasis-associated proteins MMP2 and MMP9. Conclusion Mangiferin strongly inhibited the progression of human epithelial ovarian cancer by down-regulating MMP2 and MMP9.

Activation of class I phosphatidylinositol 3-kinase (PI3K) leads to formation of phosphatidylinositol-3,4,5-trisphophate (PIP3) and phosphatidylinositol-3,4-bisphophate (PI34P2), which spatiotemporally coordinate and regulate a myriad of cellular processes. By simultaneous quantitative imaging of PIP3 and PI34P2 in live cells, we here show that they have a distinctively different spatiotemporal distribution and history in response to growth factor stimulation, which allows them to selectively induce the membrane recruitment and activation of Akt isoforms. PI34P2 selectively activates Akt2 at both the plasma membrane and early endosomes, whereas PIP3 selectively stimulates Akt1 and Akt3 exclusively at the plasma membrane. These spatiotemporally distinct activation patterns of Akt isoforms provide a mechanism for their differential regulation of downstream signaling molecules. Collectively, our studies show that different spatiotemporal dynamics of PIP3 and PI34P2 and their ability to selectively activate key signaling proteins allow them to mediate class I PI3K signaling pathways in a spatiotemporally specific manner.

Rhizoma alismatis (the rhizome of Alisma orientalis) polysaccharides (RAP) have been reported to have a variety of important biological activities. However, effective extraction of RAP has been an unsolved issue. In this study, we used an ultrasound method for high yield extraction of RAP and optimized the conditions using the response surface methodology (RSM). Following multiple regression analyses of the experimental results, we applied the 3-D response surface and the contour plots to determine the optimal conditions, which were found to be ultrasound treatment at 76.1°C for 75.2 min, and water to material ratio at 30.1 ml/g. Under such conditions, the yield was 6.90% which was much higher than traditional hot water extraction yield (3.41%). The fractionated RAPs following stepwise ethanol precipitation showed strong antioxidant activities. The results indicated that ultrasound extraction was a very effective method for the extraction of RAP and the polysaccharides could be explored as a potential antioxidant agent for use in medicine or functional food.

Background Ovarian cancer is one of the three leading gynecological malignancies, characterized by insidious growth, highly frequent metastasis, and quick development of drug resistance. As a result, this disease has low 5-year survival rates. Estrogen receptor inhibitors were commonly used for the treatment, but only 7% to 18% of patients respond to anti-estrogen therapies. Therefore, more effective therapies to inhibit estrogen-related tumors are urgently needed. Recently, phytoestrogens, such as lignans with estrogen-like biological activities, have attracted attention for their potential effects in the prevention or treatment of estrogen-related diseases. Enterodiol (END) and enterolactone (ENL) are mammalian lignans, which can reduce the risk of various cancers. However, the effects of END and ENL on ovarian cancer are not adequately documented. Methods We used in vitro assays on the ES-2 cell line to evaluate the inhibiting effects of END and ENL on ovarian cancer cell proliferation, invasion and migration ability and in vivo xenograft experiments on nude mice to validate the anticancer effects of END and ENL. Results The in vitro assays demonstrated that high-dose END and ENL could obviously inhibit ovarian malignant properties, including cancerous proliferation, invasion, and metastasis. Compared to END, ENL behaved in a better time-dose dependent manner on the cancer cells. The in vivo experiments showed that END (1 mg/kg), ENL (1 mg/kg) and ENL (0.1 mg/kg) suppressed tumor markedly, and there were statistically significant differences between the experimental and control groups in tumor weight and volume. Compared to END, which have serious side effects to the animals at high concentration such as 1 mg/kg, ENL had higher anticancer activities and less side effects in the animals than END at the same concentrations, so it would be a better candidate for drug development. Conclusion END and ENL both have potent inhibitory effects on ovarian cancer but ENL possesses a more effective anti-cancer capability and less side effects than END. Findings in this work provide novel insights into ovarian cancer therapeutics with phytoestrogens and encourage their clinical applications.

Highly conserved short sequences help identify functional genomic regions and facilitate genomic annotation. We used Salmonella as the model to search the genome for evolutionarily conserved regions and focused on the tetranucleotide sequence CTAG for its potentially important functions. In Salmonella, CTAG is highly conserved across the lineages and large numbers of CTAG-containing short sequences fall in intergenic regions, strongly indicating their biological importance. Computer modeling demonstrated stable stem-loop structures in some of the CTAG-containing intergenic regions, and substitution of a nucleotide of the CTAG sequence would radically rearrange the free energy and disrupt the structure. The postulated degeneration of CTAG takes distinct patterns among Salmonella lineages and provides novel information about genomic divergence and evolution of these bacterial pathogens. Comparison of the vertically and horizontally transmitted genomic segments showed different CTAG distribution landscapes, with the genome amelioration process to remove CTAG taking place inward from both terminals of the horizontally acquired segment.

Membrane lipids are dynamic molecules and their local concentrations serve as regulatory signals for diverse biological processes. To achieve quantitative in situ imaging of various lipids, we developed a ratiometric analysis using fluorescence biosensors, each of which is composed of an engineered lipid-binding protein and a covalently attached solvatochromic fluorophore. To cover a wide range of lipid concentration, lipid-binding proteins are engineered to have variable dynamic ranges. These tunable sensors allow robust and sensitive in situ quantitative lipid imaging in mammalian cells, providing new insight into the spatiotemporal dynamics and fluctuation of key signaling lipids. The sensor strategy is also applicable to in situ quantification of multiple cellular lipids or a single lipid in the opposing leaflets of cell membranes.

Lipids regulate a wide range of biological activities. Since their local concentrations are tightly controlled in a spatiotemporally specific manner, the simultaneous quantification of multiple lipids is essential for elucidation of the complex mechanisms of biological regulation. Here, we report a new method for the simultaneous in situ quantification of two lipid pools in mammalian cells using orthogonal fluorescent sensors. The sensors were prepared by incorporating two environmentally sensitive fluorophores with minimal spectral overlap separately into engineered lipid-binding proteins. Dual ratiometric analysis of imaging data allowed accurate, spatiotemporally resolved quantification of two different lipids on the same leaflet of the plasma membrane or a single lipid on two opposite leaflets of the plasma membrane of live mammalian cells. This new imaging technology should serve as a powerful tool for systems-level investigation of lipid-mediated cell signaling and regulation.

Ten polysaccharides were extracted from five categories of tea with hot water and further fractionated by stepwise ethanol precipitation. The polysaccharides were characterized by Fourier transform infrared spectroscopy (FT-IR) and the components including sulfuric radical, aminohexose and uronic acid were determined. All analyzed polysaccharides had antioxidant activities, with polysaccharides-II being stronger than polysaccharides-I and the antioxidant activity of the tea polysaccharides was closely related with the contents of functional groups in the polysaccharides. Our results suggest that the tea polysaccharides could be explored as a potential antioxidant agent for use in medicine or functional foods. On the other hand, the different antioxidant activities of samples provided an important reference for choosing the suitable kind of tea in application.

Understanding the microtubule-dependent behaviors of viruses in live cells is very meaningful for revealing the mechanisms of virus infection and endocytosis. Herein, we used a quantum dots-based single-particle tracking technique to dynamically and globally visualize the microtubule-dependent transport behaviors of influenza virus in live cells. We found that the intersection configuration of microtubules can interfere with the transport behaviors of the virus in live cells, which lead to the changing and long-time pausing of the transport behavior of viruses. Our results revealed that most of the viruses moved along straight microtubules rapidly and unidirectionally from the cell periphery to the microtubule organizing center (MTOC) near the bottom of the cell, and the viruses were confined in the grid of microtubules near the top of the cell and at the MTOC near the bottom of the cell. These results provided deep insights into the influence of entire microtubule geometry on the virus infection.

Enterodiol (END) possesses the estrogenic and antiestrogenic activities, which could prevent the development of breast cancer and prostate cancer, as well as menopausal syndrome. Previous studies in our laboratory set up a bio-transformation method for largely yielding secoisolariciresinol (SECO) from the substrate of defatted flaxseeds by strain Bacteroides uniformis ZL-I. In this research, another two single colonies, designated as strain ZL-II and strain ZL-III, were isolated, which were closely related to Eubacterium limosum species (ZL-II), and Eggerthella lenta species (ZL-III) on the basis of 16S rRNA gene sequence data. Under the combining actions of strains ZL-(I + II + III), END could be produced from defatted flaxseed directly, ZL-II was proved to possess the activities of demethylation, while ZL-III had the activities of dehydroxylation. Secoisolariciresinol diglucoside (SDG) existed in the form of oligomeric with 3-hydroxy-3-methyl glutaric acid in flaxseed could be efficiently transformed into END under the co-culture of strains ZL-(I + II + III), with the conversion rate of more than 90%. The method for mass-producing END from defatted flaxseed reported here is meaningful not only for the medicinal values of END but also for the resource utilization of flaxseed materials.

The plasma membrane in mammalian cells is rich in cholesterol, but how the cholesterol is partitioned between the two leaflets of the plasma membrane remains a matter of debate. Recently, Liu et al. used domain 4 (D4) of perfringolysin O as a cholesterol sensor to argue that cholesterol is mostly in the exofacial leaflet (Liu et al., 2017). This conclusion was made by interpreting D4 binding in live cells using in vitro calibrations with liposomes. However, liposomes may be unfaithful in mimicking the plasma membrane, as we demonstrate here. Also, D4 binding is highly sensitive to the presence of cytosolic proteins. In addition, we find that a D4 variant, which requires >35 mol% cholesterol to bind to liposomes in vitro, does in fact bind to the cytoplasmic leaflet of the plasma membrane in a cholesterol-dependent manner. Thus, we believe, based on the current evidence, that it is unlikely that there is a significantly higher proportion of cholesterol in the exofacial leaflet of the plasma membrane compared to the cytosolic leaflet.

Collagens in the atherosclerotic plaque signal regulation of cell behavior and provide tensile strength to the fibrous cap. Type VIII collagen, a short-chain collagen, is up-regulated in atherosclerosis; however, little is known about its functions in vivo. We studied the response to arterial injury and the development of atherosclerosis in type VIII collagen knockout mice (Col8(-/-) mice). After wire injury of the femoral artery, Col8(-/-) mice had decreased vessel wall thickening and outward remodeling when compared with Col8(+/+) mice. We discovered that apolipoprotein E (ApoE) is an endogenous repressor of the Col8a1 chain, and, therefore, in ApoE knockout mice, type VIII collagen was up-regulated. Deficiency of type VIII collagen in ApoE(-/-) mice (Col8(-/-);ApoE(-/-)) resulted in development of plaques with thin fibrous caps because of decreased smooth muscle cell migration and proliferation and reduced accumulation of fibrillar type I collagen. In contrast, macrophage accumulation was not affected, and the plaques had large lipid-rich necrotic cores. We conclude that in atherosclerosis, type VIII collagen is up-regulated in the absence of ApoE and functions to increase smooth muscle cell proliferation and migration. This is an important mechanism for formation of a thick fibrous cap to protect the atherosclerotic plaque from rupture.

SummaryArterial stiffening is a risk factor for cardiovascular disease, but how arteries stay supple is unknown. Here, we show that apolipoprotein E (apoE) and apoE-containing high-density lipoprotein (apoE-HDL) maintain arterial elasticity by suppressing the expression of extracellular matrix genes. ApoE interrupts a mechanically driven feed-forward loop that increases the expression of collagen-I, fibronectin, and lysyl oxidase in response to substratum stiffening. These effects are independent of the apoE lipid-binding domain and transduced by Cox2 and miR-145. Arterial stiffness is increased in apoE null mice. This stiffening can be reduced by administration of the lysyl oxidase inhibitor BAPN, and BAPN treatment attenuates atherosclerosis despite highly elevated cholesterol. Macrophage abundance in lesions is reduced by BAPN in vivo, and monocyte/macrophage adhesion is reduced by substratum softening in vitro. We conclude that apoE and apoE-containing HDL promote healthy arterial biomechanics and that this confers protection from cardiovascular disease independent of the established apoE-HDL effect on cholesterol.

Eubacterium limosum ZL-II was described to convert secoisolariciresinol (SECO) to its demethylating product 4,4′-dihydroxyenterodiol (DHEND) under anoxic conditions. However, the reaction cascade remains unclear. Here, the O-demethylase being responsible for the conversion was identified and characterized. Nine genes encoding two methyltransferase-Is (MT-I), two corrinoid proteins (CP), two methyltransferase-IIs (MT-II), and three activating enzymes (AE) were screened, cloned, and expressed in Escherichia coli. Four of the nine predicted enzymes, including ELI_2003 (MT-I), ELI_2004 (CP), ELI_2005 (MT-II), and ELI_0370 (AE), were confirmed to constitute the O-demethylase in E. limosum ZL-II. The complete O-demethylase (combining the four components) reaction system was reconstructed in vitro. As expected, the demethylating products 3-demethyl-SECO and DHEND were both produced. During the reaction process, ELI_2003 (MT-I) initially catalyzed the transfer of methyl group from SECO to the corrinoid of ELI_2004 ([CoI]-CP), yielding demethylating products and [CH3-CoIII]-CP; then ELI_2005 (MT-II) mediated the transfer of methyl group from [CH3-CoIII]-CP to tetrahydrofolate, forming methyltetrahydrofolate and [CoI]-CP. Due to the low redox potential of [CoII]/[CoI], [CoI]-CP was oxidized to [CoII]-CP immediately in vitro, and ELI_0370 (AE) was responsible for catalyzing the reduction of [CoII]-CP to its active form [CoI]-CP. The active-site residues in ELI_2003, ELI_2005, and ELI_0370 were subsequently determined using molecular modeling combined with site-directed mutagenesis. To our knowledge, this is the first study on the identification and characterization of a four-component O-demethylase from E. limosum ZL-II, which will facilitate the development of method to artificial synthesis of related bioactive chemicals.

Adhesive interactions between cells are needed to maintain tissue architecture during development, tissue renewal and wound healing. Thrombomodulin (TM) is an integral membrane protein that participates in cell-cell adhesion through its extracellular lectin-like domain. However, the molecular basis of TM-mediated cell-cell adhesion is poorly understood. Here, we demonstrate that TM is linked to the actin cytoskeleton via ezrin. In vitro binding assays showed that the TM cytoplasmic domain bound directly to the N-terminal domain of ezrin. Mutational analysis of the TM cytoplasmic domain identified (522)RKK(524) as important ezrin-binding residues. In epidermal epithelial A431 cells, TM colocalized with ezrin and actin filaments at cell-cell contacts. Knockdown of endogenous TM expression by RNA interference induced morphological changes and accelerated cell migration in A431 cells. Moreover, epidermal growth factor, upstream of ezrin activation, stimulated the interaction between ezrin and TM. In skin wound healing of mice, TM and ezrin were highly expressed in neoepidermis, implying that both proteins are key molecules in reepithelialization that requires collective cell migration of epithelial cells. Finally, exogenous expression of TM in TM-deficient melanoma A2058 cells promoted collective cell migration. In summary, TM, which associates with ezrin and actin filaments, maintains epithelial morphology and promotes collective cell migration.

This article has introduced and evaluated the various methods of study on carbon emissions, and makes a comparison on the research conclusion by using these methods. We has classified the influence factors of carbon emissions into three primary factors such as technical factor, structure factor and scale factor, respectively including six secondary factors such as carbon emission intensity and energy intensity; energy structure and industrial structure; economic scale, population size.

Secoisolariciresinol (SECO) is a natural lignan-type phytoestrogen constituent mainly found in flaxseed. It can be metabolized in vivo to mammalian lignans of enterodiol and enterolactone, which have been proven to be effective in relieving menopausal syndrome. Depression is one of the most common symptoms of menopausal syndrome, and is currently treated with estrogen replacement and antidepressant therapy. However, due to the serious side-effects of such agents, there are urgent needs for safer and more tolerable treatments. In this paper, using two classical depression models, the forced swimming test and the tail suspension test, we report the antidepressant effect of SECO on ovariectomized (OVX) mice by intragastric administration for 14 consecutive days at doses of 5, 10 and 20 mg/kg. The results showed that SECO (10 mg/kg) treatment could significantly reduce the duration of immobility of OVX mice in these two models compared with the control group (OVX mice + vehicle), which was similar to the positive control imipramine. In addition, SECO treatment could substantially increase brain monoamine (norepinephrine and dopamine) levels in OVX mice. The present studies showed that SECO can reverse depressive-like behavior and exhibit monoamine-enhancing effects.

The paper focuses on the dynamics optimization of the pin joints which determine the operating performance and life of a novel Large-diameter Coal-bed Methane Reaming Tool (LCMRT). For this purpose, the constraint force equations of the pin joints for LCMRT are first established using Newton-Euler dynamics theory. Moreover, the virtual prototype model of LCMRT is created for dynamics simulations. Based on the dynamics simulations, the constraint forces of the pin joints are shown. Size optimization results for LCMRT are exhibited and described in detail through parametric model. Finally, the results of dynamics simulations based on the LCMRT optimized are demonstrated to validate optimization effect.

Arterial stiffening is a hallmark of aging and risk factor for cardiovascular disease, yet its regulation is poorly understood. Here we use mouse modeling to show that matrix metalloproteinase-12 (MMP12), a potent elastase, is essential for acute and chronic arterial stiffening. MMP12 was induced in arterial smooth muscle cells (SMCs) after acute vascular injury. As determined by genome-wide analysis, the magnitude of its gene induction exceeded that of all other MMPs as well as those of the fibrillar collagens and lysyl oxidases, other common regulators of tissue stiffness. A preferential induction of SMC MMP12, without comparable effect on collagen abundance or structure, was also seen during chronic arterial stiffening with age. In both settings, deletion of MMP12 reduced elastin degradation and blocked arterial stiffening as assessed by atomic force microscopy and immunostaining for stiffness-regulated molecular markers. Isolated MMP12-null SMCs sense extracellular stiffness normally, indicating that MMP12 causes arterial stiffening by remodeling the SMC microenvironment rather than affecting the mechanoresponsiveness of the cells themselves. In human aortic samples, MMP12 levels strongly correlate with markers of SMC stiffness. We conclude that MMP12 causes arterial stiffening in mice and suggest that it functions similarly in humans.

Real-time tracking of fluorophore-tagged viruses in living cells can help uncover virus infection mechanisms. Certainly, the indispensable prerequisite for virus-tracking is to label viruses with some bright and photostable beacons such as quantum dots (QDs) via an appropriate labeling strategy. Herein, we devise a convenient hydrazine-aldehyde based strategy to label viruses with QDs through the conjugation of 4-formylbenzoate (4FB) modified QDs to 6-hydrazinonicotinate acetone hydrazone (HyNic) modified viruses under mild conditions. On the basis of this strategy, viruses can be successfully labeled with QDs with high selectivity, stable conjugation, good reproducibility, high labeling efficiency of 92-93% and maximum retention of both fluorescence properties of QDs and infectivity of viruses, which is very meaningful to tracking and statistical analysis of virus infection processes. By further comparing with the most widely used labeling strategy based on the Biotin-SA system, this new strategy has advantages of both high labeling efficiency and good retention of virus infectivity, thus offering a promising alternative for virus-labeling. Moreover, due to the ubiquitous presence of exposed amino groups on the surface of various viruses, this selective, efficient, reproducible and biofriendly strategy should have good universality for labeling both enveloped and nonenveloped viruses.

Surface-nitrided nickel foil and particle films were prepared through the nitridation of metallic nickel foil and particle films in ammonia atmosphere. The microstructure of the obtained surface ni...

Aims Macrophage-related oxidative stress plays an important role in the inflammatory process in atherosclerosis. Recently, dextromethorphan (DXM), a common cough-suppressing ingredient with a high safety profile, was found to inhibit the activation of microglia, the resident macrophage in the nervous system. We investigated whether DXM could reduce macrophage production of cytokines and superoxide and the resultant influence on atherosclerosis formation in mice. Methods and results We used in vitro and in vivo studies to evaluate the DXM inhibitory effect on oxidative stress. Dextromethorphan pretreatment significantly suppressed the production of tumour necrosis factor-α, monocyte chemoattractant protein-1, interleukin-6, interleukin-10, and superoxide in macrophage cell culture after stimulation. Indeed, DXM reduced macrophage nicotinamide adenine dinucleotide phosphate oxidase activity by decreasing membrane translocation of p47phox and p67phox through the inhibition of protein kinase C and extracellular signal-regulated kinase activation. The anti-atherosclerosis effect of DXM was tested using two animal models, apolipoprotein E (apoE)-deficient mice and a mouse carotid ligation model. Dextromethorphan treatment (10–40 mg/kg/day) for 10 weeks in apoE-deficient mice significantly reduced superoxide production in their polymorphonuclear leukocytes and aortas. It significantly decreased the severity of aortic atherosclerosis in the apoE-deficient mice and decreased carotid neointima formation after ligation in C57BL/6 mice. Conclusion Our data show that DXM, with its novel effect in reducing oxidative stress, significantly reduces atherosclerosis and neointima formation in mice.

Antrodia camphorata (AC) is a well-known traditional Chinese medicine that has been shown to inhibit proliferation and migration of cancer cells. We examined whether AC could inhibit rat aortic smooth muscle cell (RASMC) proliferation and migration and evaluated its effect on neointima formation in mouse carotid artery after injury. In Transwell migration assay and wound scratch assay, RASMCs were treated with AC or saline, and the number of migrated cells was counted or the distance was determined. Both assays showed that AC significantly inhibited platelet-derived growth factor (PDGF)-induced SMC migration. In 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and 5-bromo-2' deoxyuridine (BrdU) proliferation assays, RASMCs were pretreated with AC or saline and stimulated with PDGF. Both assays showed that AC inhibited PDGF-induced SMC proliferation. The left common carotid arteries of C57BL/6 mice were ligated near the carotid bifurcation. The mice were given water or AC for 4 weeks. The severity of neointima formation was expressed as the neointima/media (N/M) ratio. The AC-treated mice had less neointima formation at 4 weeks after carotid ligation (N/M ratio, water versus 250 versus 1250 mg/kg AC; 1.33 +/- 0.87 versus 0.83 +/- 0.45 versus 0.63 +/- 0.32, P0.05).Our data indicate that AC is an effective inhibitor of PDGF-induced RASMC proliferation and migration. AC treatment reduced neointima formation in this mouse carotid ligation model.