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Find video protocols related to scientific articles indexed in Pubmed.
FabH Mutations Confer Resistance to FabF-Directed Antibiotics in Staphylococcus aureus.
Antimicrob. Agents Chemother.
PUBLISHED: 11-19-2014
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Delineating the mechanisms for genetically acquired antibiotic resistance is a robust approach to target validation and anticipates the evolution of clinical drug resistance. This study defines a spectrum of mutations in fabH that render Staphylococcus aureus resistant to multiple natural products known to inhibit the elongation condensing enzyme (FabF) of bacterial type II fatty acid synthesis. Twenty independently-isolated clones resistant to platensimycin, platencin or thiolactomycin were isolated. All mutants selected against one antibiotic were cross-resistant to the other two antibiotics. Mutations were not detected in fabF, but the resistant strains harbored missense mutations in fabH. The altered amino acids clustered in and around the FabH active site tunnel. The mutant FabH proteins were catalytically compromised based on the low activities of the purified enzymes, a fatty acid-dependent growth phenotype and elevated expression of the fabHF operon in the mutant strains. Independent manipulation of fabF and fabH expression levels showed that the FabH:FabF activity ratio was a major determinant of antibiotic sensitivity. Missense mutations that reduce FabH activity are sufficient to confer resistance to multiple antibiotics that bind to the FabF acyl-enzyme intermediate in S. aureus.
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The immunologic and hematopoietic profiles of mesenchymal stem cells derived from different sections of human umbilical cord.
Acta Biochim. Biophys. Sin. (Shanghai)
PUBLISHED: 11-05-2014
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Mesenchymal stem cells (MSCs) have been widely used in allogeneic stem cell transplantation. We compared immunologic and hematopoietic characteristics of MSCs derived from whole human umbilical cord (UC), as well as from different sections of UCs, including the amniotic membrane (AM), Wharton's jelly (WJ), and umbilical vessel (UV). Cell phenotypes were examined by flow cytometry. Lymphocyte transformation test and mixed lymphocyte reaction were performed to evaluate the immuno-modulatory activity of MSCs derived from UCs. The mRNA expression of cytokines was detected by real-time polymerase chain reaction. Hematopoietic function was studied by co-culturing MSCs with CD34(+) cells isolated from cord blood. Our results showed that MSCs separated from these four different sections including UC, WJ, UV, and AM had similar biological characteristics. All of the MSCs had multi-lineage differentiation ability and were able to differentiate into osteoblasts, adipocytes, and chondrocytes. The MSCs also inhibited the proliferation of allogeneic T cells in a dose-dependent manner. The relative mRNA expression of cytokines was examined, and the results showed that UCMSCs had higher interleukin-6 (IL6), IL11, stem cell factor, and FLT3 expression than MSCs derived from specific sections of UCs. CD34(+) cells had high propagation efficiencies when co-cultured with MSCs derived from different sections of UCs, among which UCMSCs are the most efficient feeding layer. Our study demonstrated that MSCs could be isolated from whole UC or specific sections of UC with similar immunomodulation and hematopoiesis supporting characteristics.
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Spontaneous resolution of polyoxometalate-based inorganic-organic hybrids driven by solvent and common ion.
Dalton Trans
PUBLISHED: 10-15-2014
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Three single-sided, triol-functionalized Anderson POM hybrids were successfully synthesized. With suitable solvents and the effect driven by common-ion synergy, enantiopure crystals were obtained when the spontaneous resolution of enantiomers occurred upon crystallization. The chirality of POM-organic hybrids was confirmed by single-crystal X-ray diffraction and solid-state CD spectrum. A reversible, spontaneous resolution process for POM-based inorganic-organic hybrids was observed in this work.
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Iron-catalyzed direct difunctionalization of alkenes with dioxygen and sulfinic acids: a highly efficient and green approach to ?-ketosulfones.
Org. Biomol. Chem.
PUBLISHED: 08-28-2014
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A novel iron-catalyzed direct difunctionalization of alkenes with sulfinic acids and dioxygen for the synthesis of ?-ketosulfones has been developed under mild conditions. The present protocol, which utilizes an inexpensive iron salt as the catalyst, readily available benzenesulfinic acids as the sulfonylating reagents, and dioxygen as the oxidant and oxygen source, provides a cost-effective and environmentally benign approach to access various ?-ketosulfones.
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MOLECULAR CLONING AND CHARACTERIZATION OF A SID-1-LIKE GENE IN Plutella xylostella.
Arch. Insect Biochem. Physiol.
PUBLISHED: 08-18-2014
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RNA interference (RNAi) signal can spread from the point where the double-stranded RNA (dsRNA) was initially applied to other cells or tissues. SID-related genes in Caenorhabditis elegans help in the spreading of this signal. However, the mechanisms of systemic RNAi are still not unveiled in insects. In this study, we cloned a full-length cDNA of sid-1-like gene, Pxylsid-1, from Plutella xylostella that contains 1,047 bp opening reading frame encoding a putative protein of 348 amino acids. This transcript is very much similar to the sil-1 in Bombyx mori (68.8%). The higher expression levels of Pxylsid-1 were found at the adult and fourth-instar stages compared to the second-instar stage with 21.48- and 10.36-fold increase, respectively. Its expression levels in different tissues were confirmed with the highest expression in the hemolymph, which showed 21.09-fold increase than the midgut; however it was lower in other tissues. The result of RNAi by feeding bacterially expressed dsRNA targeting Pxylace-1, which showed that the mRNA level of Pxylace-1 decreased by 34.52 and 64.04% after 36- and 72-h treatment, respectively. However, the mRNA level of Pxylsid-1 was not significantly induced when the Pxylace-1 was downregulated. Furthermore, we found that downregulation of Pxylsid-1 did not affect the RNAi effect of Pxylace-1. Hence, the Pxylsid-1 may not be involved in absorption of dsRNA from the midgut fluid. A further study is needed to uncover the function of Pxylsid-1.
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Formation of monatomic metallic glasses through ultrafast liquid quenching.
Nature
PUBLISHED: 08-06-2014
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It has long been conjectured that any metallic liquid can be vitrified into a glassy state provided that the cooling rate is sufficiently high. Experimentally, however, vitrification of single-element metallic liquids is notoriously difficult. True laboratory demonstration of the formation of monatomic metallic glass has been lacking. Here we report an experimental approach to the vitrification of monatomic metallic liquids by achieving an unprecedentedly high liquid-quenching rate of 10(14) K s(-1). Under such a high cooling rate, melts of pure refractory body-centred cubic (bcc) metals, such as liquid tantalum and vanadium, are successfully vitrified to form metallic glasses suitable for property interrogations. Combining in situ transmission electron microscopy observation and atoms-to-continuum modelling, we investigated the formation condition and thermal stability of the monatomic metallic glasses as obtained. The availability of monatomic metallic glasses, being the simplest glass formers, offers unique possibilities for studying the structure and property relationships of glasses. Our technique also shows great control over the reversible vitrification-crystallization processes, suggesting its potential in micro-electromechanical applications. The ultrahigh cooling rate, approaching the highest liquid-quenching rate attainable in the experiment, makes it possible to explore the fast kinetics and structural behaviour of supercooled metallic liquids within the nanosecond to picosecond regimes.
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Low on-resistance diamond field effect transistor with high-k ZrO2 as dielectric.
Sci Rep
PUBLISHED: 07-15-2014
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Although several high-k insulators have been deposited on the diamond for metal-insulator-semiconductor field effect transistors (MISFETs) fabrication, the k values and current output are still not fully satisfactory. Here, we present a high-k ZrO2 layer on the diamond for the MISFETs. The k value for ZrO2 is determined by capacitance-voltage characteristic to be 15.4. The leakage current density is smaller than 4.8 × 10(-5) A · cm(-2) for the gate voltage ranging from -4.0 to 2.0 V. The low on-resistance MISFET is obtained by eliminating source/drain-channel interspaces, which shows a large current output and a high extrinsic transconductance. The high-performance diamond MISFET fabrication will push forward the development of power devices.
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Void-assisted plasticity in Ag nanowires with a single twin structure.
Nanoscale
PUBLISHED: 07-10-2014
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By employing the in situ transmission electron microscopy (TEM) technique, tensile deformation behaviors of a silver nanowire (NW) with a single twin structure were studied. Our observations revealed that the initial stage of plastic deformation was dominated by surface-mediated partial dislocation activities. Strikingly, the void formation and growth were shown to govern the later stage of plasticity, leading to the ductile type of fracture in NWs. Possible void nucleation and growth mechanisms were discussed. Additionally, TEM images show the transformation from bi-crystal to polycrystal in the fracture area, likely due to the void activity. Our results have implications in the assembly of functional structures applying nano-building blocks.
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Aliphatic Organoimido Derivatives of Polyoxometalates Containing a Bioactive Ligand.
Chemistry
PUBLISHED: 07-09-2014
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A series of aliphatic organoimido derivatives of hexamolybdate based on amantadine, namely (nBu4 N)2 [Mo6 O18 (?NC10 H15 )] (1), (nBu4 N)2 {cis-[Mo6 O17 (?NC10 H15 )2 ]} (2), (nBu4 N)2 {trans-[Mo6 O17 (?NC10 H15 )2 ]} (3), and (nBu4 N)2 [Mo6 O16 (?NC10 H15 )3 ] (4), was synthesized in reasonable yield by dehydration with N,N'-dicyclohexylcarbodiimide (DCC). They were characterized by IR and UV/Vis spectroscopy, elemental analysis, ESI mass spectrometry, and single-crystal X-ray structure analysis. The spectral and structural similarities and differences between monosubstituted, cis-disubstituted, and trans-disubstituted organoimido derivatives were elucidated and may provide guidance for related work on organoimido-functionalized Lindqvist-type polyoxometalates. In addition, trans-disubstituted and polysubstituted derivatives containing aliphatic organoimido ligands have not yet been reported, and the crystal structure of the trans isomer may lead us to a deeper understanding of disubstituted derivatives. Furthermore, proliferation and morphology of MCF-7 cells were studied with compound 1. The present results show that the DCC-dehydrating protocol could be an efficient approach to covalently graft bioactive ligands such as amantadine onto POMs and enhance their application in clinical cancer treatment.
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High-throughput colorimetric assays for mercury(II) in blood and wastewater based on the mercury-stimulated catalytic activity of small silver nanoparticles in a temperature-switchable gelatin matrix.
Chem. Commun. (Camb.)
PUBLISHED: 07-05-2014
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A catalysis-based, label-free, and high-throughput colorimetric protocol has been initially proposed for detecting mercury(II) in blood and wastewater with 96-cell plates, based on the mercury-enhanced catalytic activity of small silver nanoparticles synthesized in a gelatin matrix with unique temperature switchable sol-gel transition.
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Porphodilactones as synthetic chlorophylls: relative orientation of ?-substituents on a pyrrolic ring tunes NIR absorption.
J. Am. Chem. Soc.
PUBLISHED: 06-24-2014
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Porphodilactones represent the porphyrin analogues, in which the peripheral bonds of two pyrrole rings are replaced by lactone moieties. They provide an opportunity to investigate how ?-substituent orientation of porphyrinoids modulates the electronic structures and optical properties, in a manner similar to what is observed with naturally occurring chlorophylls. In this work, a comprehensive description of the synthesis, characterization, and optical properties of meso-tetrakispentafluorophenylporphodilactone isomers is first reported. The ?-dilactone moieties are found to lie at opposite pyrrole positions (trans- and cis-configurations are defined by the relative orientations of the carbonyl group when one lactone moiety is fixed), in accordance with earlier computational predictions (Gouterman, M. J. Am. Chem. Soc. 1989, 111, 3702). The relative orientation of the ?-dilactone moieties has a significant influence on the electronic structures and photophysical properties. For example, the Qy band of trans-porphodilactone is red-shifted by 19 nm relative to that of the cis-isomer, and there is a 2-fold increase in the absorption intensity, which resembles the similar trends that have been reported for natural chlorophyll f and d. An in depth analysis of magnetic circular dichroism spectral data and TD-DFT calculations at the B3LYP/6-31G(d) level of theory demonstrates that the trans- and cis-orientations of the dilactone moieties have a significant effect on the relative energies of the frontier ?-molecular orbitals. Importantly, the biological behaviors of the isomers reveal their different photocytotoxicity in NIR region (>650 nm). The influence of the relative orientation of the ?-substituents on the optical properties in this context provides new insights into the electronic structures of porphyrinoids which could prove useful during the development of near-infrared absorbing photosensitizers.
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Type II fatty acid synthesis is essential for the replication of Chlamydia trachomatis.
J. Biol. Chem.
PUBLISHED: 06-23-2014
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The major phospholipid classes of the obligate intracellular bacterial parasite Chlamydia trachomatis are the same as its eukaryotic host except that they also contain chlamydia-made branched-chain fatty acids in the 2-position. Genomic analysis predicts that C. trachomatis is capable of type II fatty acid synthesis (FASII). AFN-1252 was deployed as a chemical tool to specifically inhibit the enoyl-acyl carrier protein reductase (FabI) of C. trachomatis to determine whether chlamydial FASII is essential for replication within the host. The C. trachomatis FabI (CtFabI) is a homotetramer and exhibited typical FabI kinetics, and its expression complemented an Escherichia coli fabI(Ts) strain. AFN-1252 inhibited CtFabI by binding to the FabI·NADH complex with an IC50 of 0.9 ?M at saturating substrate concentration. The x-ray crystal structure of the CtFabI·NADH·AFN-1252 ternary complex revealed the specific interactions between the drug, protein, and cofactor within the substrate binding site. AFN-1252 treatment of C. trachomatis-infected HeLa cells at any point in the infectious cycle caused a decrease in infectious titers that correlated with a decrease in branched-chain fatty acid biosynthesis. AFN-1252 treatment at the time of infection prevented the first cell division of C. trachomatis, although the cell morphology suggested differentiation into a metabolically active reticulate body. These results demonstrate that FASII activity is essential for C. trachomatis proliferation within its eukaryotic host and validate CtFabI as a therapeutic target against C. trachomatis.
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Photosensing performance of branched CdS/ZnO heterostructures as revealed by in situ TEM and photodetector tests.
Nanoscale
PUBLISHED: 06-12-2014
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CdS/ZnO branched heterostructures have been successfully synthesized by combining thermal vapour deposition and a hydrothermal method. Drastic optoelectronic performance enhancement of such heterostructures was revealed, compared to plain CdS nanobelts, as documented by comparative in situ optoelectronic studies on corresponding individual nanostructures using an originally designed laser-compatible transmission electron microscopy (TEM) technique. Furthermore, flexible thin-film based photodetectors based on standard CdS nanobelts and newly prepared CdS/ZnO heterostructures were fabricated on PET substrates, and comparative photocurrent and photo-responsivity measurements thoroughly verified the in situ TEM results. The CdS/ZnO branched heterostructures were found to have better performance than standard CdS nanobelts for optoelectronic applications with respect to the photocurrent to dark current ratio and responsivity.
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Activation of Liver X Receptor Improves Viability of Adipose-Derived Mesenchymal Stem Cells to Attenuate Myocardial Ischemia Injury Through TLR4/NF-?B and Keap-1/Nrf-2 Signaling Pathways.
Antioxid. Redox Signal.
PUBLISHED: 06-11-2014
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Abstract Aims: Clinical application of cellular therapy for cardiac regeneration is significantly hampered by the low retention of engrafted cells, mainly attributable to the poor microenvironment dominated by inflammation and oxidative stress in the host's infarcted myocardium. This study aims at investigating whether liver X receptor (LXR) agonist T0901317 will improve survival of adipose-derived mesenchymal stem cells (AD-MSCs) after transplantation into infarcted hearts. Results: Noninvasive in vivo bioluminescence imaging and histological staining showed that LXR agonist T0901317 improved the retention and survival of intramyocardially injected AD-MSCs. Moreover, combined therapy of LXR agonist and AD-MSCs inhibited host cardiomyocyte apoptosis, reduced fibrosis, and improved cardiac function, while it concomitantly decreased inflammatory cytokines (e.g., tumor necrosis factor-? and interleukin-6) and increased growth factor (e.g., vascular endothelial growth factor and basic fibroblast growth factor) expression in infarct myocardium. To reveal possible mechanisms, AD-MSCs were subjected to hypoxia/serum deprivation (H/SD) injury to simulate ischemic conditions in vivo. The LXR agonist (10(-7) mM) improved AD-MSC survival under H/SD condition. Western blot revealed that the LXR agonist reduced TLR4, TRAF-6, and MyD88 protein expression, inhibited I?B? phosphorylation and NF-?B-p65 nuclear translocation, which resulted in accelerated Keap-1 protein degradation, enhanced Nrf-2 nuclear translocation, and increased HO-1 protein expression. Innovation and Conclusion: LXR agonist can enhance the functional survival of transplanted AD-MSCs in infarcted myocardium, at least partially, via modulation of the TLR4/NF-?B and Keap-1/Nrf-2 signaling pathways. Moreover, combined therapy of LXR agonist and AD-MSCs has a synergetic effect on cardiac repair and functional improvement after infarction. Antioxid. Redox Signal. 00, 000-000.
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Genome-wide investigation of genetic changes during modern breeding of Brassica napus.
Theor. Appl. Genet.
PUBLISHED: 05-29-2014
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Considerable genome variation had been incorporated within rapeseed breeding programs over past decades. In past decades, there have been substantial changes in phenotypic properties of rapeseed as a result of extensive breeding effort. Uncovering the underlying patterns of allelic variation in the context of genome organisation would provide knowledge to guide future genetic improvement. We assessed genome-wide genetic changes, including population structure, genetic relatedness, the extent of linkage disequilibrium, nucleotide diversity and genetic differentiation based on F ST outlier detection, for a panel of 472 Brassica napus inbred accessions using a 60 k Brassica Infinium® SNP array. We found genetic diversity varied in different sub-groups. Moreover, the genetic diversity increased from 1950 to 1980 and then remained at a similar level in China and Europe. We also found ~6-10 % genomic regions revealed high F ST values. Some QTLs previously associated with important agronomic traits overlapped with these regions. Overall, the B. napus C genome was found to have more high F ST signals than the A genome, and we concluded that the C genome may contribute more valuable alleles to generate elite traits. The results of this study indicate that considerable genome variation had been incorporated within rapeseed breeding programs over past decades. These results also contribute to understanding the impact of rapeseed improvement on available genome variation and the potential for dissecting complex agronomic traits.
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A multifunctional nanomicelle for real-time targeted imaging and precise near-infrared cancer therapy.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 05-21-2014
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Simultaneous targeted cancer imaging, therapy and real-time therapeutic monitoring can prevent over- or undertreatment. This work describes the design of a multifunctional nanomicelle for recognition and precise near-infrared (NIR) cancer therapy. The nanomicelle encapsulates a new pH-activatable fluorescent probe and a robust NIR photosensitizer, R16FP, and is functionalized with a newly screened cancer-specific aptamer for targeting viable cancer cells. The fluorescent probe can light up the lysosomes for real-time imaging. Upon NIR irradiation, R16FP-mediated generation of reactive oxygen species causes lysosomal destruction and subsequently trigger lysosomal cell death. Meanwhile the fluorescent probe can reflect the cellular status and in?situ visualize the treatment process. This protocol can provide molecular information for precise therapy and therapeutic monitoring.
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Pharmaceuticals and personal care products in a mesoscale subtropical watershed and their application as sewage markers.
J. Hazard. Mater.
PUBLISHED: 05-19-2014
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This study comprehensively analyzed 23 classes of 51 pharmaceuticals and personal care products (PPCPs) in the two major prongs of Jiulong River and its estuary in southeast China, where the levels of the targeted PPCPs were mostly unknown. For both Jiulong River and its estuary, nine PPCPs were detected with 100% detection frequencies including two anti-inflammatory and analgesic drugs (ketoprofen and diclofenac acid), a stimulant (caffeine), a plasticizer (bisphenol A), two preservatives (methyl paraben and propyl paraben), two antimicrobials (triclosan and triclocarban) and a ?-blocks (metoprolol), among which bisphenol A and caffeine accounted for more than 60% in concentrations. PPCPs generally had higher concentrations in dry season than normal season and wet season, while certain PPCPs, such as UV filters, showed higher concentrations in wet season, which were presumed to be related to their usage patterns. The concentrations of PPCPs were significantly correlated to several quality parameters of the surface water. The selected sewage markers were also used to track sewage in the studied river and the ratios of easily removed markers and conservative markers were used to identify the contribution of raw or treated sewage input. From our result, Jiulong River and its estuary were likely polluted by potential discharge of raw sewage.
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In situ transmission electron microscopy study of electrochemical sodiation and potassiation of carbon nanofibers.
Nano Lett.
PUBLISHED: 05-19-2014
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Carbonaceous materials have great potential for applications as anodes of alkali-metal ion batteries, such as Na-ion batteries and K-ion batteries (NIB and KIBs). We conduct an in situ study of the electrochemically driven sodiation and potassiation of individual carbon nanofibers (CNFs) by transmission electron microscopy (TEM). The CNFs are hollow and consist of a bilayer wall with an outer layer of disordered-carbon (d-C) enclosing an inner layer of crystalline-carbon (c-C). The d-C exhibits about three times volume expansion of the c-C after full sodiation or potassiation, thus suggesting a much higher storage capacity of Na or K ions in d-C than c-C. For the bilayer CNF-based electrode, a steady sodium capacity of 245 mAh/g is measured with a Coulombic efficiency approaching 98% after a few initial cycles. The in situ TEM experiments also reveal the mechanical degradation of CNFs through formation of longitudinal cracks near the c-C/d-C interface during sodiation and potassiation. Geometrical changes of the tube are explained by a chemomechanical model using the anisotropic sodiation/potassiation strains in c-C and d-C. Our results provide mechanistic insights into the electrochemical reaction, microstructure evolution and mechanical degradation of carbon-based anodes during sodiation and potassiation, shedding light onto the development of carbon-based electrodes for NIBs and KIBs.
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[The role of RNA pooling technique in the diagnosis of acute HIV infection and the estimation on HIV incidence among low-grade-venues female sex workers].
Zhonghua Liu Xing Bing Xue Za Zhi
PUBLISHED: 05-17-2014
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To examine the feasibility of RNA pooling technique in the diagnosis on acute HIV infection among female sex workers (FSWs) working at the low-grade venues.
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Evaluation of occipitocervical neutral position using lateral radiographs.
J Orthop Surg Res
PUBLISHED: 05-13-2014
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Intraoperative assessment of neutral occipitocervical balance during a fusion procedure is challenging. We designed this study to introduce a more comprehensive method of evaluating the occipitocervical neutral position using lateral radiographs.
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[Effects of CD147 gene silencing on protein expression of ANXA2, MMP-2 and TIMP-2 by thyroid medullary carcinoma TT cells and biologic characteristics].
Zhonghua Bing Li Xue Za Zhi
PUBLISHED: 04-19-2014
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To study the influence of CD147 gene silencing on the expression of ANXA2, MMP-2 and TIMP-2 of thyroid medullary carcinoma TT cells and related biological characteristics.
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Comparison of the risk of breakage of two kinds of sacroiliac screws in the treatment of bilateral sacral fractures.
Eur Spine J
PUBLISHED: 04-10-2014
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This study aimed at comparing the risk of breakage of lengthened sacroiliac screw and ordinary sacroiliac screw for the treatment of bilateral vertical sacral fractures to provide reference for clinical application.
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Metal-free direct trifluoromethylation of activated alkenes with Langlois' reagent leading to CF3-containing oxindoles.
J. Org. Chem.
PUBLISHED: 04-10-2014
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A metal-free and cost-effective synthesis protocol has been initially proposed for the construction of CF3-containing oxindoles via the direct oxidative trifluoromethylation of activated alkenes with Langlois' reagent (CF3SO2Na). The present methodology, which utilizes very cheap CF3 reagent and a simple oxidant, provides a convenient and practical approach to CF3-containing oxindoles with a wide variety of functional groups.
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Protective effect of Salvia miltiorrhiza aqueous extract on myocardium oxidative injury in ischemic-reperfusion rats.
Gene
PUBLISHED: 03-20-2014
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Salvia miltiorrhiza has strong antioxidative activity. They may have a strong potential as cardioprotective agents in ischemic-reperfusion injury. Experiments were carried out in Sprague-Dawley rats with myocardium ischemia reperfusion (IR). Myocardial injuries during IR were determined by changes in electrocardiogram analysis of arrhythmias, antioxidant enzyme activities, AST, CK-MB, lactate dehydrogenase (LDH) levels, and myocyte apoptosis. Results showed that S. miltiorrhiza aqueous extract (SAME) pre-treatment significantly decreased the ST-segment (?ST120) and myocardium MDA, AST, CK-MB, lactate dehydrogenase (LDH) levels, increased myocardium antioxidant enzyme activities, and inhibit myocardium cell apoptosis. Furthermore, the SAME pre-treatment significantly upregulated p-JAK2 and p-STAT3 protein expression, decreased myocardium TNF-? and IL-6 concentrations in IR rats. The levels of TNF-? and IL-6 were positively correlated with the changes in myocardium p-JAK2 and p-STAT3 protein expression levels in IR rats. It can be concluded that the SAME pre-treatment has anti-ischemic and anti-apoptosis activity in heart IR rats. SAME pre-treatment protects heart against IR injury, at least in part, through its stimulating effects on injury-induced deactivation of JAK2/STAT3 signaling pathway.
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Melaminivora alkalimesophila gen. nov., sp. nov., a melamine-degrading betaproteobacterium isolated from a melamine-producing factory.
Int. J. Syst. Evol. Microbiol.
PUBLISHED: 03-03-2014
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A taxonomic study was carried out on strain CY1(T), which is a novel bacterium isolated from wastewater sludge of a melamine-producing factory in Sanming city, Fujian, China. Strain CY1(T) was shown to rapidly and completely degrade melamine to NH3 and CO2 under aerobic conditions. The isolate was Gram-stain-negative, short-rod-shaped and motile by one unipolar flagellum. Growth was observed at salinities from 0 to 7% NaCl (optimum, 0.1%), at temperatures from 15 to 50 °C (optimum, 40-45 °C) and at pH 7-9.5 (optimum pH 9.5). Quinone-8 was detected as the major respiratory quinone. 16S rRNA gene sequence comparisons showed that strain CY1(T) was affiliated to the family Comamonadaceae in the class Betaproteobacteria. It was most closely related to members of the genera Alicycliphilus (95.5%), Diaphorobacter (94.6-95.1%), Acidovorax (92.9-95.4%), Delftia (93.0-93.6%) and Comamonas (92.6-93.9%). The average nucleotide identity (ANI) values between strain CY1(T) and those representing related genera ranged from 84.0 to 86.1% using Mummer, and from 74.9 to 81.1% using BLAST. The dominant fatty acids were C(16?:?1)?7c and/or C(16?:?1)?6c, C(16?:?0), C(10?:?0) 3-OH and C(18?:?1)?7c and/or C(18?:?1)?6c, and the major polar lipids consisted of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, one unidentified phospholipid and one unidentified aminophospholipid. The G+C content of the chromosomal DNA was 69.5 mol%. On the basis of the phenotypic and phylogenetic data, strain CY1(T) represents a novel species of a new genus, for which the name Melaminivora alkalimesophila gen. nov., sp. nov. is proposed. The type strain of Melaminivora alkalimesophila is CY1(T) (?=?CCTCC AB 2012024(T)?=?DSM 26006(T)).
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Characterization of miRNomes in acute and chronic myeloid leukemia cell lines.
Genomics Proteomics Bioinformatics
PUBLISHED: 02-25-2014
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Myeloid leukemias are highly diverse diseases and have been shown to be associated with microRNA (miRNA) expression aberrations. The present study involved an in-depth miRNome analysis of two human acute myeloid leukemia (AML) cell lines, HL-60 and THP-1, and one human chronic myeloid leukemia (CML) cell line, K562, via massively parallel signature sequencing. mRNA expression profiles of these cell lines that were established previously in our lab facilitated an integrative analysis of miRNA and mRNA expression patterns. miRNA expression profiling followed by differential expression analysis and target prediction suggested numerous miRNA signatures in AML and CML cell lines. Some miRNAs may act as either tumor suppressors or oncomiRs in AML and CML by targeting key genes in AML and CML pathways. Expression patterns of cell type-specific miRNAs could partially reflect the characteristics of K562, HL-60 and THP-1 cell lines, such as actin filament-based processes, responsiveness to stimulus and phagocytic activity. miRNAs may also regulate myeloid differentiation, since they usually suppress differentiation regulators. Our study provides a resource to further investigate the employment of miRNAs in human leukemia subtyping, leukemogenesis and myeloid development. In addition, the distinctive miRNA signatures may be potential candidates for the clinical diagnosis, prognosis and treatment of myeloid leukemias.
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Synthesis and anticancer activity of novel quinoline-docetaxel analogues.
Bioorg. Med. Chem. Lett.
PUBLISHED: 02-24-2014
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A series of novel quinoline-docetaxel analogues (6a-6g, 13a-13g) were designed and synthesized by introducing bioactive quinoline scaffold to C2'-OH of docetaxel. The anticancer activities of these novel analogues were investigated against different human cancer cell lines including Hela, A549, A2780, MCF-7 and two resistant strains A2780-MDR and MCF-7-MDR. The data showed these analogues possessed similar to better cytotoxicity than docetaxel. Compound 6c was found to be the most potent one, and its IC50 value against MCF-7-MDR was 8.8 nM (IC50 of docetaxel was 180 nM). The work indicated that the introduction of quinolyl group in docetaxel could enhance cytotoxicity and reduce drug-resistance.
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Comparison of the heat stress induced variations in DNA methylation between heat-tolerant and heat-sensitive rapeseed seedlings.
Breed. Sci.
PUBLISHED: 02-16-2014
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DNA methylation is responsive to various biotic and abiotic stresses. Heat stress is a serious threat to crop growth and development worldwide. Heat stress results in an array of morphological, physiological and biochemical changes in plants. The relationship between DNA methylation and heat stress in crops is relatively unknown. We investigated the differences in methylation levels and changes in the cytosine methylation patterns in seedlings of two rapeseed genotypes (heat-sensitive and heat-tolerant) under heat stress. Our results revealed that the methylation levels were different between a heat-tolerant genotype and a heat-sensitive one under control conditions. Under heat treatment, methylation increased more in the heat-sensitive genotype than in the heat-tolerant genotype. More DNA demethylation events occurred in the heat-tolerant genotype, while more DNA methylation occurred in the heat-sensitive genotype. A large and diverse set of genes were affected by heat stress via cytosine methylation changes, suggesting that these genes likely play important roles in the response and adaption to heat stress in Brassica napus L. This study indicated that the changes in DNA methylation differed between heat-tolerant and heat-sensitive genotypes of B. napus in response to heat stress, which further illuminates the molecular mechanisms of the adaption to heat stress in B. napus.
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Whole transcriptome RNA-seq analysis: tumorigenesis and metastasis of melanoma.
Gene
PUBLISHED: 02-13-2014
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Melanoma is the most malignant cutaneous cancer and causes over 9000 deaths annually. Because fatality rates from malignant melanoma (MM) increase dramatically upon metastasis, we investigated tumorigenesis and metastasis of MM in transcriptome analyses of three distinct cell lines that correspond with the stages of MM pathogenesis: the normal stage (HEMn-LP), the onset of MM (A375), and the metastasis stage (A2058). Using next-generation sequencing (NGS) technology, we detected asymmetrical expression of genes among the three cell lines, notably on chromosomes 9, 11, 12, and 14, suggesting their involvement in tumorigenesis and metastasis of MM. These genes were clustered into 41 categories based on their expression patterns, and their biological functions were analyzed using Ingenuity Pathway Analysis. In the top cancer-associated category, HIF1A, IL8, TERT, ONECUT1, and FOXA1 directly interacted with either transcription factors or cytokines that are known to be involved in the tumorigenesis or metastasis of other malignant tumors. The present data suggest that cytokine regulatory pathways in macrophages predominate over other pathways during the pathogenesis of MM. This study provides new targets for the downstream mechanistic studies of the tumorigenesis and metastasis of MM and demonstrates a new strategy for studies of the progression of other malignant cancers.
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Flexible ultraviolet photodetectors with broad photoresponse based on branched ZnS-ZnO heterostructure nanofilms.
Adv. Mater. Weinheim
PUBLISHED: 02-12-2014
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The application of nanofilm networks made of branched ZnS-ZnO nanostructures as a flexible UV photodetector is demonstrated. The fabricated devices show excellent operational characteristics: tunable spectral selectivity, widerange photoresponse, fast response speed, and excellent environmental stability.
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Copper-catalyzed highly selective direct hydrosulfonylation of alkynes with arylsulfinic acids leading to vinyl sulfones.
Org. Biomol. Chem.
PUBLISHED: 02-12-2014
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A novel Cu-catalyzed direct hydrosulfonylation of alkynes with arylsulfinic acids for the synthesis of (E)-vinyl sulfones has been realized under mild conditions with 100% atom efficiency. The present protocol provides an attractive approach to various vinyl sulfones in good to excellent yields, with the advantages of operation simplicity, atom economy, and high stereo- and regioselectivities.
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Anti-inflammatory effects of vinpocetine on the functional expression of nuclear factor-kappa B and tumor necrosis factor-alpha in a rat model of cerebral ischemia-reperfusion injury.
Neurosci. Lett.
PUBLISHED: 02-09-2014
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The restoration of blood flow to the brain after ischemic stroke prevents further, extensive damage but can result in reperfusion injury. The inflammation response is one of many factors involved in cerebral ischemia-reperfusion injury. This study investigated the use of vinpocetine, a drug used to treat cognitive impairment, to explore its effects on inflammation in a rat model of cerebral ischemia-reperfusion.
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Genome-wide association study dissects the genetic architecture of seed weight and seed quality in rapeseed (Brassica napus L.).
DNA Res.
PUBLISHED: 02-07-2014
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Association mapping can quickly and efficiently dissect complex agronomic traits. Rapeseed is one of the most economically important polyploid oil crops, although its genome sequence is not yet published. In this study, a recently developed 60K Brassica Infinium(®) SNP array was used to analyse an association panel with 472 accessions. The single-nucleotide polymorphisms (SNPs) of the array were in silico mapped using 'pseudomolecules' representative of the genome of rapeseed to establish their hypothetical order and to perform association mapping of seed weight and seed quality. As a result, two significant associations on A8 and C3 of Brassica napus were detected for erucic acid content, and the peak SNPs were found to be only 233 and 128 kb away from the key genes BnaA.FAE1 and BnaC.FAE1. BnaA.FAE1 was also identified to be significantly associated with the oil content. Orthologues of Arabidopsis thaliana HAG1 were identified close to four clusters of SNPs associated with glucosinolate content on A9, C2, C7 and C9. For seed weight, we detected two association signals on A7 and A9, which were consistent with previous studies of quantitative trait loci mapping. The results indicate that our association mapping approach is suitable for fine mapping of the complex traits in rapeseed.
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Effects of cannabinoid receptor type 2 on endogenous myocardial regeneration by activating cardiac progenitor cells in mouse infarcted heart.
Sci China Life Sci
PUBLISHED: 01-15-2014
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Cannabinoid receptor type 2 (CB2) activation is recently reported to promote proliferation of some types of resident stem cells (e.g., hematopoietic stem/progenitor cell or neural progenitor cell). Resident cardiac progenitor cell (CPC) activation and proliferation are crucial for endogenous cardiac regeneration and cardiac repair after myocardial infarction (MI). This study aims to explore the role and possible mechanisms of CB2 receptor activation in enhancing myocardial repair. Our results revealed that CB2 receptor agonist AM1241 can significantly increase CPCs by c-kit and Runx1 staining in ischemic myocardium as well as improve cardiomyocyte proliferation. AM1241 also decreased serum levels of MDA, TNF-? and IL-6 after MI. In addition, AM1241 can ameliorate left ventricular ejection fraction and fractional shortening, and reduce fibrosis. Moreover, AM1241 treatment markedly increased p-Akt and HO-1 expression, and promoted Nrf-2 nuclear translocation. However, PI3K inhibitor wortmannin eliminated these cardioprotective roles of AM1241. In conclusion, AM1241 could induce myocardial regeneration and improve cardiac function, which might be associated with PI3K/Akt/Nrf2 signaling pathway activation. Our findings may provide a promising strategy for cardiac endogenous regeneration after MI.
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In search of antiaging modalities: evaluation of mTOR- and ROS/DNA damage-signaling by cytometry.
Cytometry A
PUBLISHED: 01-07-2014
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This review presents the evidence in support of the IGF-1/mTOR/S6K1 signaling as the primary factor contributing to aging and cellular senescence. Reviewed are also specific interactions between mTOR/S6K1 and ROS-DNA damage signaling pathways. Outlined are critical sites along these pathways, including autophagy, as targets for potential antiaging (gero-suppressive) and/or chemopreventive agents. Presented are applications of flow- and laser scanning- cytometry utilizing phospho-specific Abs, to monitor activation along these pathways in response to the reported antiaging drugs rapamycin, metformin, berberine, resveratrol, vitamin D3, 2-deoxyglucose, and acetylsalicylic acid. Specifically, effectiveness of these agents to attenuate the level of constitutive mTOR signaling was tested by cytometry and confirmed by Western blotting through measuring phosphorylation of the mTOR-downstream targets including ribosomal protein S6. The ratiometric analysis of phosphorylated to total protein along the mTOR pathway offers a useful parameter reporting the effects of gero-suppressive agents. In parallel, their ability to suppress the level of constitutive DNA damage signaling induced by endogenous ROS was measured. While the primary target of each of these agents may be different the data obtained on several human cancer cell lines, WI-38 fibroblasts and normal lymphocytes suggest common downstream mechanism in which the decline in mTOR/S6K1 signaling and translation rate is coupled with a reduction of oxidative phosphorylation and ROS that leads to decreased oxidative DNA damage. The combined assessment of constitutive ?H2AX expression, mitochondrial activity (ROS, ??m), and mTOR signaling provides an adequate gamut of cell responses to test effectiveness of gero-suppressive agents. Described is also an in vitro model of induction of cellular senescence by persistent replication stress, its quantitative analysis by laser scanning cytometry, and application to detect the property of the studied agents to attenuate the induction of senescence. Discussed is cytometric analysis of cell size and heterogeneity of size as a potential biomarker used to asses gero-suppressive agents and longevity.
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Effect of methotrexate on the mechanical properties and microstructure of calcium phosphate cement.
Orthopedics
PUBLISHED: 01-05-2014
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Calcium phosphate cement (CPC) is widely used as an antitumor bone-filling material. Methotrexate (MTX) is recognized as an effective chemotherapy medicine. The current study examined the effects of MTX on the mechanical properties and microstructure of CPC. Methotrexate-loaded CPC at mass ratios of 0%, 0.1%, 0.2%, and 0.5% were designated as groups A, B, C, and D, respectively, and were pressed into precast cylindrical molds. Solidification time, axial compressive strength, transverse compressive strength, and rotational tensile strength were measured, and scanning electron microscopy images were captured before and after MTX-CPC microstructure changes occurred. Average initial and final setting times increased gradually with increasing drug concentration, but this increase was not significant among the groups. Average axial transverse compressive strength and rotational tensile strength of groups B and C were not significantly different from those of group A (P>.05); however, there was a significant difference in these properties between groups A and D (P<.05). Scanning electron microscopy observations showed a porous crystalline structure. The addition of MTX to CPC does not significantly affect the basic crystal structure and setting time of CPC. Adding MTX at mass ratios of 0.1% and 0.2% to CPC does not lead to a significant difference in mechanical strength and can therefore be applied in clinical practice. This study may shed some light on the future application of MTX-loaded CPC in the treatment of bone defects after tumor excision.
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Screening for acute HIV infections and estimating HIV incidence among female sex workers from low-grade venues in Guangxi, China.
PLoS ONE
PUBLISHED: 01-01-2014
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Guangxi has become one of the provinces with the most severe HIV-1 epidemic in China, where heterosexual contact is the dominant transmission route. However, data of acute HIV infections and HIV incidence among female sex workers (FSWs) from low-grade venues are scant.
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Identification of novel and conserved microRNAs related to drought stress in potato by deep sequencing.
PLoS ONE
PUBLISHED: 01-01-2014
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MicroRNAs (miRNAs) are a group of small, non-coding RNAs that play important roles in plant growth, development and stress response. There have been an increasing number of investigations aimed at discovering miRNAs and analyzing their functions in model plants (such as Arabidopsis thaliana and rice). In this research, we constructed small RNA libraries from both polyethylene glycol (PEG 6,000) treated and control potato samples, and a large number of known and novel miRNAs were identified. Differential expression analysis showed that 100 of the known miRNAs were down-regulated and 99 were up-regulated as a result of PEG stress, while 119 of the novel miRNAs were up-regulated and 151 were down-regulated. Based on target prediction, annotation and expression analysis of the miRNAs and their putative target genes, 4 miRNAs were identified as regulating drought-related genes (miR811, miR814, miR835, miR4398). Their target genes were MYB transcription factor (CV431094), hydroxyproline-rich glycoprotein (TC225721), quaporin (TC223412) and WRKY transcription factor (TC199112), respectively. Relative expression trends of those miRNAs were the same as that predicted by Solexa sequencing and they showed a negative correlation with the expression of the target genes. The results provide molecular evidence for the possible involvement of miRNAs in the process of drought response and/or tolerance in the potato plant.
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WBSA: web service for bisulfite sequencing data analysis.
PLoS ONE
PUBLISHED: 01-01-2014
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Whole-Genome Bisulfite Sequencing (WGBS) and genome-wide Reduced Representation Bisulfite Sequencing (RRBS) are widely used to study DNA methylation. However, data analysis is complicated, lengthy, and hampered by a lack of seamless analytical pipelines. To address these issues, we developed a convenient, stable, and efficient web service called Web Service for Bisulfite Sequencing Data Analysis (WBSA) to analyze bisulfate sequencing data. WBSA focuses on not only CpG methylation, which is the most common biochemical modification in eukaryotic DNA, but also non-CG methylation, which have been observed in plants, iPS cells, oocytes, neurons and stem cells of human. WBSA comprises three main modules as follows: WGBS data analysis, RRBS data analysis, and differentially methylated region (DMR) identification. The WGBS and RRBS modules execute read mapping, methylation site identification, annotation, and advanced analysis, whereas the DMR module identifies actual DMRs and annotates their correlations to genes. WBSA can be accessed and used without charge either online or local version. WBSA also includes the executables of the Portable Batch System (PBS) and standalone versions that can be downloaded from the website together with the installation instructions. WBSA is available at no charge for academic users at http://wbsa.big.ac.cn.
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Genome-wide survey and expression analysis of the putative non-specific lipid transfer proteins in Brassica rapa L.
PLoS ONE
PUBLISHED: 01-01-2014
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Plant non-specific lipid transfer proteins (nsLtps) are small, basic proteins encoded by multigene families and have reported functions in many physiological processes such as mediating phospholipid transfer, defense reactions against phytopathogens, the adaptation of plants to various environmental conditions, and sexual reproduction. To date, no genome-wide overview of the Brassica rapa nsLtp (BrnsLtp) gene family has been performed. Therefore, as the first step and as a helpful strategy to elucidate the functions of BrnsLtps, a genome-wide study for this gene family is necessary.
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Cell-Specific and pH-Activatable Rubyrin-Loaded Nanoparticles for Highly Selective Near-Infrared Photodynamic Therapy against Cancer.
J. Am. Chem. Soc.
PUBLISHED: 12-09-2013
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Spatiotemporal control of singlet oxygen ((1)O2) release is a major challenge for photodynamic therapy (PDT) against cancer with high therapeutic efficacy and minimum side effects. Here a selenium-rubyrin (NMe2Se4N2)-loaded nanoparticle functionalized with folate (FA) was designed and synthesized as an acidic pH-activatable targeted photosensitizer. The nanoparticles could specifically recognize cancer cells via the FA-FA receptor binding and were selectively taken up by cancer cells via receptor-mediated endocytosis to enter lysosomes, in which NMe2Se4N2 was activated to produce (1)O2. The pH-controllable release of (1)O2 specially damaged the lysosomes and thus killed cancer cells in a lysosome-associated pathway. The introduction of selenium into the rubyrin core enhanced the (1)O2 generation efficiency due to the heavy atom effect, and the substitution of dimethylaminophenyl moiety at meso-position led to the pH-controllable activation of NMe2Se4N2. Under near-infrared (NIR) irradiation, NMe2Se4N2 possessed high singlet oxygen quantum yield (??) at an acidic pH (?? = 0.69 at pH 5.0 at 635 nm) and could be deactivated at physiological pH (?? = 0.06 at pH 7.4 at 635 nm). The subcellular location-confined pH-activatable photosensitization at NIR region and the cancer cell-targeting feature led to excellent capability to selectively kill cancer cells and prevent the damage to normal cells, which greatly lowered the side effects. Through intravenous injection of FA-NMe2Se4N2 nanoparticles in tumor-bearing mice, tumor elimination was observed after NIR irradiation. This work presents a new paradigm for specific PDT against cancer and provides a new avenue for preparation of highly efficient photosensitizers.
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Resistance to AFN-1252 Arises from Missense Mutations in Staphylococcus aureus Enoyl-acyl Carrier Protein Reductase (FabI).
J. Biol. Chem.
PUBLISHED: 11-04-2013
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AFN-1252 is a potent antibiotic against Staphylococcus aureus that targets the enoyl-acyl carrier protein reductase (FabI). A thorough screen for AFN-1252-resistant strains was undertaken to identify the spectrum of mechanisms for acquired resistance. A missense mutation in fabI predicted to encode FabI(M99T) was isolated 49 times, and a single isolate was predicted to encode FabI(Y147H). AFN-1252 only bound to the NADPH form of FabI, and the close interactions between the drug and Met-99 and Tyr-147 explained how the mutations would result in resistant enzymes. The clone expressing FabI(Y147H) had a pronounced growth defect that was rescued by exogenous fatty acid supplementation, and the purified protein had less than 5% of the enzymatic activity of FabI. FabI(Y147F) was also catalytically defective but retained its sensitivity to AFN-1252, illustrating the importance of the conserved Tyr-147 hydroxyl group in FabI function. The strains expressing FabI(M99T) exhibited normal growth, and the biochemical properties of the purified protein were indistinguishable from those of FabI. The AFN-1252 Ki(app) increased from 4 nm in FabI to 69 nm in FabI(M99T), accounting for the increased resistance of the corresponding mutant strain. The low activity of FabI(Y147H) precluded an accurate Ki measurement. The strain expressing FabI(Y147H) was also resistant to triclosan; however, the strain expressing FabI(M99T) was more susceptible. Strains with higher levels of AFN-1252 resistance were not obtained. The AFN-1252-resistant strains remained sensitive to submicromolar concentrations of AFN-1252, which blocked growth through inhibition of fatty acid biosynthesis at the FabI step.
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PRDA1, a Novel Chloroplast Nucleoid Protein, is Required for Early Chloroplast Development and is Involved in the Regulation of Plastid Gene Expression in Arabidopsis.
Plant Cell Physiol.
PUBLISHED: 10-15-2013
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Chloroplast development requires accurate spatio-temporal expression of plastid genes. The regulation of plastid genes mediated by plastid-encoded RNA polymerase (PEP) is rather complex, and its related mechanism remains largely unclear. Here, we report the identification of a novel protein that is essential for plant development, PEP-Related Development Arrested 1 (PRDA1). Knock-out of PRDA1 in Arabidopsis (prda1 mutant) caused a seedling-lethal, albino phenotype and arrested the development of leaf chloroplasts. Localization analysis showed that PRDA1 was specifically targeted to chloroplasts and co-localized with chloroplast nucleoids, revealing that PRDA1 is a chloroplast nucleoid-associated protein. Gene expression analyses revealed that the PEP-dependent plastid transcript levels were greatly reduced in prda1. PRDA1 was co-expressed with most of the PEP-associated proteins. Protein interaction assays showed that PRDA1 clearly interacts with MRL7 and FSD2, both of which have been verified as essential for PEP-related chloroplast development. Reactive oxygen species scavenging through dimethylthiourea markedly alleviated the cotyledon-albino phenotypes of PRDA1 and MRL7 RNA interference seedlings. These results demonstrate that PRDA1 is required for early chloroplast development and involved in the regulation of plastid gene expression.
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Copper-catalyzed direct oxysulfonylation of alkenes with dioxygen and sulfonylhydrazides leading to ?-ketosulfones.
Chem. Commun. (Camb.)
PUBLISHED: 09-25-2013
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The first copper-catalyzed oxysulfonylation reaction of alkenes with dioxygen and sulfonylhydrazides for the construction of ?-ketosulfones has been developed under mild conditions without any ligand or additive.
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Phosphatidylglycerol Homeostasis in Glycerol-Phosphate Auxotrophs of Staphylococcus aureus.
BMC Microbiol.
PUBLISHED: 09-24-2013
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The balanced synthesis of membrane phospholipids, fatty acids and cell wall constituents is a vital facet of bacterial physiology, but there is little known about the biochemical control points that coordinate these activities in Gram-positive bacteria. In Escherichia coli, the glycerol-phosphate acyltransferase (PlsB) plays a key role in coordinating fatty acid and phospholipid synthesis, but pathogens like Staphylococcus aureus have a different acyltransferase (PlsY), and the headgroup of the major membrane phospholipid, phosphatidylglycerol (PtdGro), is used as a precursor for lipoteichoic acid synthesis.
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Characterization of a novel melamine-degrading bacterium isolated from a melamine-manufacturing factory in China.
Appl. Microbiol. Biotechnol.
PUBLISHED: 09-08-2013
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Melamine (2,4,6-triamino-1,3,5-triazine, C3H6N6), belonging to the s-triazine family, is an anthropogenic and versatile raw material for a large number of consumer products and its extensive use has resulted in the contamination of melamine in the environment. A novel melamine-degrading bacterium strain CY1 was isolated from a melamine-manufacturing factory in China. The strain is phylogenetically different from the known melamine-degrading bacteria. Approximately, 94 % melamine (initial melamine concentration 4.0 mM, initial cell OD 0.05) was degraded in 10 days without the addition of additional carbon source. High-performance liquid chromatography showed the production of degradation intermediates including ammeline, ammelide, cyanuric acid, biuret, and urea. Kinetic simulation analysis indicated that transformation of urea into ammonia was the rate-limiting step for the degradation process. The melamine-cyanurate complex was formed due to self-assembly of melamine and cyanuric acid during the degradation. The tracking experiment using CY1 cells and (13)C3-melamine showed that the CY1 could mineralize s-triazine ring carbon to CO2. The strain CY1 could also catalyze partial transformation of cyromazine, a cyclopropyl derivative of melamine, to 6-(cyclopropylamino)-[1,3,5]triazine-2,4-diol.
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Berberine suppresses gero-conversion from cell cycle arrest to senescence.
Aging (Albany NY)
PUBLISHED: 08-27-2013
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Berberine (BRB), a natural alkaloid, has a long history of medicinal use in both Ayurvedic and old Chinese medicine. Recently, available as a dietary supplement, Berberine is reported to have application in treatment of variety diseases. Previously we observed that BRB inhibited mTOR/S6 signaling concurrently with reduction of the level of endogenous oxidants and constitutive DNA damage response. We currently tested whether Berberine can affect premature, stress-induced cellular senescence caused by mitoxantrone. The depth of senescence was quantitatively measured by morphometric parameters, senescence-associated ?-galactosidase, induction of p21WAF1, replication stress (?H2AX expression), and mTOR signaling; the latter revealed by ribosomal S6 protein (rpS6) phosphorylation. All these markers of senescence were distinctly diminished, in a concentration-dependent manner, by Berberine. In view of the evidence that BRB localizes in mitochondria, inhibits respiratory electron chain and activates AMPK, the observed attenuation of the replication stress-induced cellular senescence most likely is mediated by AMPK that leads to inhibition of mTOR signaling. In support of this mechanism is the observation that rhodamine123, the cationic probe targeting mitochondrial electron chain, also suppressed rpS6 phosphorylation. The present findings reveal that: (a) in cells induced to senescence BRB exhibits gero-suppressive properties by means of mTOR/S6 inhibition; (b) in parallel, BRB reduces the level of constitutive DNA damage response, previously shown to report oxidative DNA damage by endogenous ROS; (c) there appears to a causal linkage between the (a) and (b) activities; (d) the in vitro model of premature stress-induced senescence can be used to assess effectiveness of potential gero-suppressive agents targeting mTOR/S6 and ROS signaling; (e) since most of the reported beneficial effects of BRB are in age-relate diseases, it is likely that gero-suppression is the primary activity of this traditional medicine.
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[Preparation and identification of anti-follicle-stimulating hormone receptor nanobodies].
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi
PUBLISHED: 08-17-2013
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To prepare camel derived nanobodies which specifically bind to follicle-stimulating hormone receptor (FSHR).
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TLR4-mediated anti-atherosclerosis mechanisms of angiotensin-converting enzyme inhibitor--fosinopril.
Cell. Immunol.
PUBLISHED: 07-31-2013
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Recently, angiotensin-converting enzyme inhibitor (ACEI) has gained increasing attention for its anti-atherosclerosis activity, but the underlying mechanism is unknown. In our study, we used rabbits fed with high-fat forage, as an atherosclerosis model to investigate the effect of fosinopril, which is an ACEI. Animals which received both high-fat forage and fosinopril, were maintained as the drug-treated group. Ultrasonography and Sudan III staining were used to determine the process of atherosclerosis. The expression of TLR4 and activity NF-?B were determined using western blot, RT-PCR and ELISA. The results showed that the atherosclerotic plaque was visible at sixteen weeks. More importantly, the atherosclerotic plaque was significantly decreased after fosinopril treatment. In the atherosclerosis model, the levels of TLR4 and NF-?B were increased, but this increased expression was inhibited in the fosinopril treated group. Our results demonstrated that TLR4 could be used as a potential biomarker for atherosclerosis and ACEI has the potential to be a new anti-atherosclerotic drug.
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A tuberous sclerosis complex signalling node at the peroxisome regulates mTORC1 and autophagy in response to ROS.
Nat. Cell Biol.
PUBLISHED: 07-10-2013
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Subcellular localization is emerging as an important mechanism for mTORC1 regulation. We report that the tuberous sclerosis complex (TSC) signalling node, TSC1, TSC2 and Rheb, localizes to peroxisomes, where it regulates mTORC1 in response to reactive oxygen species (ROS). TSC1 and TSC2 were bound by peroxisomal biogenesis factors 19 and 5 (PEX19 and PEX5), respectively, and peroxisome-localized TSC functioned as a Rheb GTPase-activating protein (GAP) to suppress mTORC1 and induce autophagy. Naturally occurring pathogenic mutations in TSC2 decreased PEX5 binding, and abrogated peroxisome localization, Rheb GAP activity and suppression of mTORC1 by ROS. Cells lacking peroxisomes were deficient in mTORC1 repression by ROS, and peroxisome-localization-deficient TSC2 mutants caused polarity defects and formation of multiple axons in neurons. These data identify a role for the TSC in responding to ROS at the peroxisome, and identify the peroxisome as a signalling organelle involved in regulation of mTORC1.
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Transcriptome dynamics during human erythroid differentiation and development.
Genomics
PUBLISHED: 06-24-2013
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To explore the mechanisms controlling erythroid differentiation and development, we analyzed the genome-wide transcription dynamics occurring during the differentiation of human embryonic stem cells (HESCs) into the erythroid lineage and development of embryonic to adult erythropoiesis using high throughput sequencing technology. HESCs and erythroid cells at three developmental stages: ESER (embryonic), FLER (fetal), and PBER (adult) were analyzed. Our findings revealed that the number of expressed genes decreased during differentiation, whereas the total expression intensity increased. At each of the three transitions (HESCs-ESERs, ESERs-FLERs, and FLERs-PBERs), many differentially expressed genes were observed, which were involved in maintaining pluripotency, early erythroid specification, rapid cell growth, and cell-cell adhesion and interaction. We also discovered dynamic networks and their central nodes in each transition. Our study provides a fundamental basis for further investigation of erythroid differentiation and development, and has implications in using ESERs for transfusion product in clinical settings.
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Decomposition of NO in automobile exhaust by plasma-photocatalysis synergy.
Environ Sci Pollut Res Int
PUBLISHED: 05-30-2013
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The combination of plasma discharge and TiO2 photocatalysis exhibits high performances in the removal of nitrogen monoxide (NO). This article is aimed at elucidating the relationships between NO decomposition efficiency and various experimental parameters, including voltages, humidity and temperature. The experimental results indicate that the efficiency of NO removal by synergic plasma-catalyst coupling is significantly higher than plasma only or photocatalyst only systems. Moreover, the NO removal efficiency improves with the increase of applied voltage. Meanwhile, a higher humidity results in a reduced number of electron-hole pairs at the surface of TiO2 photocatalyst, leading to lower synergic purification efficiencies. Finally, the efficiency of NO removal is raised with the increase of temperature due to the fact that the adsorption of NO and water by nano-TiO2 is affected by environmental temperature.
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Fosinoprilat alleviates lipopolysaccharide (LPS)-induced inflammation by inhibiting TLR4/NF-?B signaling in monocytes.
Cell. Immunol.
PUBLISHED: 04-19-2013
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To evaluate the effect of the fosinoprilat on lipopolysacharides (LPS) induced inflammation in monocytes in vitro.
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Near-ideal theoretical strength in gold nanowires containing angstrom scale twins.
Nat Commun
PUBLISHED: 03-19-2013
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Although nanoscale twinning is an effective means to enhance yield strength and tensile ductility in metals, nanotwinned metals generally fail well below their theoretical strength limit due to heterogeneous dislocation nucleation from boundaries or surface imperfections. Here we show that Au nanowires containing angstrom-scaled twins (0.7 nm in thickness) exhibit tensile strengths up to 3.12 GPa, near the ideal limit, with a remarkable ductile-to-brittle transition with decreasing twin size. This is opposite to the behaviour of metallic nanowires with lower-density twins reported thus far. Ultrahigh-density twins (twin thickness<2.8 nm) are shown to give rise to homogeneous dislocation nucleation and plastic shear localization, contrasting with the heterogeneous slip mechanism observed in single-crystalline or low-density-twinned nanowires. The twin size dependent dislocation nucleation and deformation represent a new type of size effect distinct from the sample size effects described previously.
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Dermatic Scedosporium apiospermum infection after autologous bone marrow transplantation.
Intern. Med.
PUBLISHED: 03-15-2013
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Infection with Scedosporium apiospermum (S. apiospermum) is rare, although it is associated with a high fatality rate, especially in immunosuppressed patients. A 23-year-old man with acute myelogenous leukemia (AML) (M2) who was pretreated with chemotherapy for autologous bone marrow transplantation developed a skin ulcer on the left groin. After a culture study demonstrated the presence of S. apiospermum, voriconazole was administered and the lesion rapidly improved. Since a diagnosis of S. apiospermum continues to depend on the results of a fungal culture and most isolates of S. apiospermum are resistant to amphotericin B, voriconazole should be considered as the first choice when "mold" is thought to be the causative organism.
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Magnetic properties and spin dynamics in Ba(Fe(1-x)Mn(x))2As2 compounds studied by 57Fe Mössbauer spectroscopy.
J Phys Condens Matter
PUBLISHED: 03-11-2013
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Ba(Fe(1-x)Mn(x))2As2 compounds with x = 0.016 and 0.064 have been studied by (57)Fe Mössbauer spectroscopy in the temperature range from 30 to 300 K. The unusual magnetic splitting spectra at lower temperatures have been analyzed using the distribution of hyperfine field. It is found that the influence of Mn dopant spreads beyond the nearest Fe magnetic moments, and the Fe 3d electrons behave more localized compared with those in the electron-doped compounds. This reduces the hyperfine interactions between iron nucleus and the sounding electrons. The shape of the spin density wave is near-rectangular at 6.4%-Mn doping, indicating quite different interband interactions compared with electron-doped compounds. A distinct broadening of the spectral linewidth around the spin density wave transition temperature has been observed and the spin correlation time is deduced according to the linewidth. The correlation time is further related to the spin-lattice relaxation rate by a simple model and the magnetic fluctuations can be explored effectively. It is found that the magnetic fluctuations of iron spins in Mn-doped compounds can be described well using a phenomenological two-component model and the resulting Curie-Weiss temperature is far from the quantum critical point at the present doping levels.
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Dynamic transcriptomes of human myeloid leukemia cells.
Genomics
PUBLISHED: 03-01-2013
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To identify the mechanisms controlling chronic myeloid leukemia (CML) and acute myeloid leukemia (AML) in humans, we analyzed genome-wide transcription dynamics in three myeloid leukemia cell lines (K562, HL-60, and THP1) using high-throughput sequencing technology. Using KEGG analysis, we found that the ERK/MAPK, JAK-STAT and ErbB pathways promoted proliferation and metabolism in CML. However, in AML, differentiation and apoptosis blocking resulted in the accumulation of blast cells in marrow. In addition, each cell type had unique characteristics. K562 cells are an ideal model for studying erythroid differentiation and globin gene expression. The chemokine signaling pathway and Fc gamma R-mediated phagocytosis were markedly upregulated in HL-60 cells. In THP1 cells, highly expressed genes ensured strong phagocytosis by monocytes. Further, we provide a new insight into myeloid development. The abundant data sets and well-defined analysis methods will provide a resource and strategy for further investigation of myeloid leukemia.
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DNA damage signaling, impairment of cell cycle progression, and apoptosis triggered by 5-ethynyl-2-deoxyuridine incorporated into DNA.
Cytometry A
PUBLISHED: 02-27-2013
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The "click chemistry" approach utilizing 5-ethynyl-2-deoxyuridine (EdU) as a DNA precursor was recently introduced to assess DNA replication and adapted to flow- and imaging-cytometry. In the present study, we observed that EdU, once incorporated into DNA, induces DNA damage signaling (DDS) such as phosphorylation of ATM on Ser1981, of histone H2AX on Ser139, of p53 on Ser15, and of Chk2 on Thr68. It also perturbs progression of cells through the cell cycle and subsequently induces apoptosis. These effects were observed in non-small cell lung adenocarcinoma A549 as well as in B-cell human lymphoblastoid TK6 and WTK1 cells, differing in the status of p53 (wt versus mutated). After 1 h EdU pulse-labeling, the most affected was cells progression through the S phase subsequent to that at which they had incorporated EdU. This indicates that DNA replication using the template containing incorporated EdU is protracted and triggers DDS. Furthermore, progression of cells having DNA pulse-labeled with EdU led to accumulation of cells in G2 , likely by activating G2 checkpoint. Consistent with the latter was activation of p53 and Chk2. Although a correlation was observed in A549 cells between the degree of EdU incorporation and the extent of ?H2AX induction, such correlation was weak in TK6 and WTK1 cells. The degree of perturbation of the cell cycle kinetics by the incorporated EdU was different in the wt p53 TK6 cells as compared to their sister WTK1 cell line having mutated p53. The data are thus consistent with the role of p53 in modulating activation of cell cycle checkpoints in response to impaired DNA replication. The confocal microscopy analysis of the 3D images of cells exposed to EdU for 1 h pulse and then grown for 24 or 48 h revealed an increased number of colocalized ?H2AX and p53BP1 foci considered to be markers of DNA double-strand breaks and enlarged nuclei.
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Prediction and verification of microRNAs related to proline accumulation under drought stress in potato.
Comput Biol Chem
PUBLISHED: 01-30-2013
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Proline is an important osmotic adjusting material greatly accumulated under drought stress and can help plant to adapt to osmotic stress. MicroRNAs (miRNAs) are small, endogenous RNAs that play important regulatory roles in plant development and stress response by negatively affecting gene expression at post-transcriptional level. Three genes of pyrroline-5-carboxylate synthetase (P5CS), pyrroline-5-carboxylate reductase (P5CR) and proline dehydrogenase (ProDH) are regulating proline metabolism. Until now, little is known about miRNAs regulating proline accumulation. In this work, in order to understand whether miRNAs related to mRNAs of enzymes to regulate proline enrichment under drought stress, we used mRNAs of related enzymes as the targets of miRNAs to search miRBase using BLAST and find many query miRNA sequences. After a range of filtering criteria, 11 known miRNAs classified into 6 miRNA families were predicted. The result from qRT-PCR assay showed that 10 out of 11 predicted miRNAs were successfully detected including 9 down-regulated miRNAs and one up-regulated miRNA. Based on expression and functional analysis, we identified miR172, miR396a, miR396c and miR4233 may regulate P5CS gene, and miR2673 and miR6461 may regulate P5CR and ProDH gene, respectively. The findings can help us make a good understanding of the roles of miRNAs in regulation of proline accumulation and provide molecular evidence for involvement process of drought tolerance in potato.
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Expression of sPLA2-V, estrogen and its target protein in myocardium tissue.
Int. J. Biol. Macromol.
PUBLISHED: 01-20-2013
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In this study, we examined the effects of Prostaglandin E1 and tea polysaccharides (TP) on serum estrogen and FSH levels, myocardium sPLA2-V positive levels, and sPLA2-V protein expression in the rats fed on hypercholesterolemic diet. Hyperlipidemic rats were treated with Prostaglandin E1 and TP. Serum estrogen and FSH levels were significantly enhanced by Prostaglandin E1 and TP, whereas myocardium sPLA2-V positive rate and protein expression levels were decreased compared to the HCD group. Our results suggest that Prostaglandin E1 and TP exert strong heart-protective effects and therefore can be used to reduce the risk of heart disorders.
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Effects of ischemic preconditioning on myocardium Caspase-3, SOCS-1, SOCS-3, TNF-? and IL-6 mRNA expression levels in myocardium IR rats.
Mol. Biol. Rep.
PUBLISHED: 01-09-2013
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The aim of this study was to characterise the effects of ischemic preconditioning (IP) on heart function parameters (?ST and ?T), activities of serum creatine kinase (CK), lactate dehydrogenase (LDH), and levels of serum nitric oxide (NO), malondialdehyde (MDA), and myocardium Caspase-3 mRNA, SOCS-1, SOCS-3, tumor necrosis factor-alpha (TNF-?) and interleukin-6 (IL-6) expression levels and Apoptosis index in myocardium IR rats. Results showed that ?ST and ?ST values in IP group were markedly lower than those in IR group. Compared with IR group, IP significantly (p < 0.01) decreased serum CK (0.83 ± 0.09 vs 1.36 ± 0.15), LDH (5613 ± 462 vs 7106 ± 492) activities and MDA (11.32 ± 1.05 vs 15.49 ± 1.26) level, increased the serum NO (86.39 ± 7.03 vs 53.77 ± 4.27) level in IR group. The IP induced a significant decreased in myocardium Caspase-3 mRNA (0.303 ± 0.021 vs 0.515 ± 0.022) gene expression (p < 0.01) compared to IR model group. The IP induced a significant decreased in myocardium SOCS-1 (0.241 ± 0.031 vs 0.596 ± 0.036), SOCS-3 (0.258 ± 0.031 vs 0.713 ± 0.057), TNF-? (0.137 ± 0.011 vs 0.427 ± 0.035) and IL-6 (0.314 ± 0.021 vs 0.719 ± 0.064) mRNA gene expression (p < 0.01) compared to IR model group. We conclude that IP is effective in the therapy of heart disease. These findings may have implications for the clinical development of preconditioning-based therapies for ischemic heart disease.
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Infusion of Trx-1-Overexpressing hucMSC Prolongs the Survival of Acutely Irradiated NOD/SCID Mice by Decreasing Excessive Inflammatory Injury.
PLoS ONE
PUBLISHED: 01-01-2013
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A protective reagent for ARI should have the ability to repair injured tissue caused by radiation and prevent continuous damage from secondary risk factors. Trx-1 was explored as a candidate therapy for ARI, as it scavenges reactive oxygen species, regulates cell growth and differentiation, participates in immune reactions, and inhibits apoptosis by acting inside and/or outside cells. Trx-1 can also decrease excessive inflammation in ARI by regulating the creation of inflamed media, by inhibiting the activation of complement, and by reducing the chemotaxis, adhesion, and migration of inflammatory cells. As effectively and stably expressing exogenous genes in the long term and regulating immune inflammation and tissue repair, MSC are a good choice for Trx-1 gene therapy. In this study, Trx-1-overexpressing hucMSC-Trx-1 were obtained by adenoviral vector-mediated infection. We first measured the redox capacity of hucMSC-Trx-1 with an antioxidant capacity (T-AOC) assay, a hydrogen peroxide (H2O2) content determination assay in vivo, a H2O2-induced oxidation hemolysis assay, and a lipid peroxidation assay in vitro. Then, we measured survival time, the protection of the hematopoietic system, and the regulation of inflammation in important organs in three treatment groups of NOD/SCID mice (treated with hucMSC-Trx-1, with hucMSC, and with saline) that were exposed to 4.5 Gy (60)Co-?-ray radiation. The hucMSC-Trx-1 group achieved superior antioxidation results, protecting bone marrow hematopoietic stem cells (Lin(-)CD117(+): hucMSC-Trx-1 vs. hucMSC, P<0.05; hucMSC-Trx-1 vs. NS, P<0.01), promoting the formation of red blood cells and hemoglobin (hucMSC-Trx-1 vs. hucMSC or NS, P<0.05), reducing inflammation and damage in important organs (Bone marrow and lung: hucMSC-Trx-1 vs. NS, P<0.01; hucMSC-Trx-1 vs. hucMSC, P<0.05. Liver and intestine: hucMSC-Trx-1 vs. NS, P<0.05; hucMSC-Trx-1 vs. hucMSC, P<0.05), and prolonging survival (hucMSC-Trx-1 vs. hucMSC or NS, P<0.01). Therefore, hucMSC-Trx-1 combines the merits of gene and cell therapy as a multifunctional radioprotector for ARI.
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Genome protective effect of metformin as revealed by reduced level of constitutive DNA damage signaling.
Aging (Albany NY)
PUBLISHED: 11-10-2011
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We have shown before that constitutive DNA damage signaling represented by H2AX-Ser139 phosphorylation and ATM activation in untreated normal and tumor cells is a reporter of the persistent DNA replication stress induced by endogenous oxidants, the by-products of aerobic respiration. In the present study we observed that exposure of normal mitogenically stimulated lymphocytes or tumor cell lines A549, TK6 and A431 to metformin, the specific activator of 5AMP-activated protein kinase (AMPK) and an inhibitor of mTOR signaling, resulted in attenuation of constitutive H2AX phosphorylation and ATM activation. The effects were metformin-concentration dependent and seen even at the pharmacologically pertinent 0.1 mM drug concentration. The data also show that intracellular levels of endogenous reactive oxidants able to oxidize 2,7-dihydro-dichlorofluorescein diacetate was reduced in metformin-treated cells. Since persistent constitutive DNA replication stress, particularly when paralleled by mTOR signaling, is considered to be the major cause of aging, the present findings are consistent with the notion that metformin, by reducing both DNA replication stress and mTOR-signaling, slows down aging and/or cell senescence processes.
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Evaluation of the antioxidant potential of Salvia miltiorrhiza ethanol extract in a rat model of ischemia-reperfusion injury.
Molecules
PUBLISHED: 11-03-2011
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The present study was undertaken to evaluate the protection potential of ethanol extract of Salvia miltiorrhiza (SMEE) against oxidative injury in the ischemia-reperfusion (I/R) model of rats in vivo. Rats were divided into six groups of 10 rats each. Group I/R model and sham were fed with a standard rat chow, groups SMEE I and SMEE II were fed with a standard rat chow and 400 or 800 mg/kg b.w. ethanol extract for 12 days before the beginning of I/R studies. Positive control group was fed with a standard rat chow and salvianolic acid B (55 mg/kg b.w.) or tanshinone II-A (55 mg/kg b.w.) for 12 days before the beginning of I/R studies. To produce I/R, the left anterior descending artery (LAD) was occluded in anesthetized rats for 15 min, followed by 120 min reperfusion. Infarct sizes were found significantly decreased in SMEE-treated and positive control groups compared to I/R model group. Serum AST, LDH and CK-MB activities were significantly reduced and myocardium Na+-K+ ATPase, Ca2+-Mg2+ ATPase activities and antioxidant enzyme activities (SOD, CAT, GSH-Px) were markedly increased in SMEE-treated and salvianolic acid B or tanshinone II-A positive control groups compared to the I/R model group. Pretreatment of S. miltiorrhiza ethanol extract and salvianolic acid B or tanshinone II-A dose-dependently reduced significantly myocardium MDA level, ROS and NOS activities and enhanced myocardium GSH level in I/R rats compared to I/R rats model. In conclusion, we clearly demonstrated that S. miltiorrhiza ethanol extract pretreatment can decrease oxidative injury in rats subjected to myocardial I/R.
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Simultaneous water desalination and electricity generation in a microbial desalination cell with electrolyte recirculation for pH control.
Bioresour. Technol.
PUBLISHED: 08-30-2011
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A recirculation microbial desalination cell (rMDC) was designed and operated to allow recirculation of solutions between the anode and cathode chambers. This recirculation avoided pH imbalances that could inhibit bacterial metabolism. The maximum power density was 931±29mW/m(2) with a 50mM phosphate buffer solution (PBS) and 776±30mW/m(2) with 25mM PBS. These power densities were higher than those obtained without recirculation of 698±10mW/m(2) (50mM PBS) and 508±11mW/m(2) (25mM PBS). The salt solution (20g/L NaCl) was reduced in salinity by 34±1% (50mM) and 37±2% (25mM) with recirculation (rMDC), and by 39±1% (50mM) and 25±3% (25mM) without recirculation (MDC). These results show that electrolyte recirculation using an rMDC is an effective method to increase power and achieve efficient desalination by eliminating pH imbalances.
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Lithiation-induced embrittlement of multiwalled carbon nanotubes.
ACS Nano
PUBLISHED: 08-12-2011
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Lithiation of individual multiwalled carbon nanotubes (MWCNTs) was conducted in situ inside a transmission electron microscope. Upon lithiation, the intertube spacing increased from 3.4 to 3.6 Å, corresponding to about 5.9% radial and circumferential expansions and ?50 GPa tensile hoop stress on the outermost tube wall. The straight tube walls became distorted after lithiation. In situ compression and tension tests show that the lithiated MWCNTs were brittle with sharp fracture edges. Such a failure mode is in stark contrast with that of the pristine MWCNTs which are extremely flexible and fail in a "sword-in-sheath" manner upon tension. The lithiation-induced embrittlement is attributed to the mechanical effect of a "point-force" action posed by the intertubular lithium that induces the stretch of carbon-carbon bonds in addition to that by applied strain, as well as the chemical effect of electron transfer from lithium to the antibonding ? orbital that weakens the carbon-carbon bond. The combined mechanical and chemical weakening leads to a considerable decrease of the fracture strain in lithiated MWCNTs. Our results provide direct evidence and understanding of the degradation mechanism of carbonaceous anodes in lithium ion batteries.
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A near-infrared reversible fluorescent probe for peroxynitrite and imaging of redox cycles in living cells.
Chem. Commun. (Camb.)
PUBLISHED: 07-22-2011
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BzSe-Cy is a small-molecule fluorescent probe containing Se, which can respond reversibly to changes in ONOO(-) or reduced ascorbate and exhibit high sensitivity and selectivity for ONOO(-).
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Cell fixation in zinc salt solution is compatible with DNA damage response detection by phospho-specific antibodies.
Cytometry A
PUBLISHED: 05-20-2011
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By virtue of superior preservation of proteins and nucleic acids the zinc salt-based fixatives (ZBF) has been proposed as an alternative to precipitants and cross-linking fixatives in histopathology. It was recently reported that ZBF is compatible with analysis of cell surface immunophenotype and detection of intracellular epitopes by flow cytometry. The aim of this study was to explore whether ZBF is also compatible with the detection of DNA damage response assessed by phospho-specific antibodies (Abs) detecting phosphorylation of the key proteins of that pathway. DNA damage in human pulmonary adenocarcinoma A549 cells was induced by treatment with the DNA topoisomerase I inhibitor camptothecin and phosphorylation of histone H2AX on Ser139 (?H2AX) and of ATM on Ser1981 was detected with phospho-specific Abs; cellular fluorescence was measured by laser scanning cytometry (LSC). The sensitivity and accuracy of detection of H2AX and ATM phosphorylation concurrent with the detection of DNA replication by EdU incorporation and "click chemistry" was found in ZBF fixed cells to be comparable to that of cell fixed in formaldehyde. The accuracy of DNA content measurement as evident from the resolution of DNA content frequency histograms of cells stained with DAPI was somewhat better in ZBF- than in formaldehyde-fixed cells. The pattern of chromatin condensation revealed by the intensity of maximal pixel of DAPI that allows one to identify mitotic and immediately post-mitotic cells by LSC was preserved after ZBF fixation. ZBF fixation was also compatible with the detection of ?H2AX foci considered to be the hallmarks of induction of DNA double-strand breaks. Analysis of cells by flow cytometry revealed that ZBF fixation of lymphoblastoid TK6 cells led to about 60 and 33% higher intensity of the side and forward light scatter, respectively, compared to formaldehyde fixed cells.
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