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Find video protocols related to scientific articles indexed in Pubmed.
The complete mitochondrial genome of the Epinephelus akaara (Perciformes: Serranidae).
Mitochondrial DNA
PUBLISHED: 11-19-2014
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Abstract The complete mitochondrial genome of the Epinephelus akaara was presented in this study. The mitochondrial genome is 16,743?bp long and consists of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a control region. The gene order and composition of Epinephelus akaara mitochondrial genome was similar to that of most other vertebrates. The nucleotide compositions of the light strand are 27.31% of A, 16.20% of C, 28.68% of T and 27.81% of G. With the exception of the NADH dehydrogenase subunit 6 (ND6) and eight tRNA genes, all other mitochondrial genes are encoded on the heavy strand.
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Deformation grating fabrication technique based on the solvent-assisted microcontact molding.
Appl Opt
PUBLISHED: 11-18-2014
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A deformation grating fabrication technique based on solvent-assisted microcontact molding (SAMIM) is reported in this paper. The fabrication process can be divided into three steps: imprinting a grating on a medium polymer substrate (MPS) by SAMIM, coating a thin metal film on the MPS, and transferring the film to the measured surface. In order to increase the stiffness of the elastic mold without decreasing its conformal contact formation ability, a re-useable, glass-embedded polydimethylsiloxane (PDMS) mold is used. In addition, a characterization method based on the Fourier transform and phase analysis is proposed to check the quality of the fabricated grating. Verified by experiment, the proposed fabrication technique can fabricate a high-frequency large-area grating on different specimens, which can be a qualified deformation sensor for the moiré method.
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Phosphonium-Organophosphate Ionic Liquids as Lubricant Additives: Effects of Cation Structure on Physicochemical and Tribological Characteristics.
ACS Appl Mater Interfaces
PUBLISHED: 11-18-2014
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Our previous work suggested great potential for a phosphonium-organophosphate ionic liquid (IL) as an anti-wear lubricant additive. In this study, a set of five ILs were carefully designed and synthesized, with identical organophosphate anions but dissimilar phosphonium cations, to allow systematic investigation of the effects of cation alkyl chain length and symmetry on physicochemical and tribological properties. Symmetric cations with shorter alkyl chains seem to increase the density and thermal stability due to closer packing. On the other hand, either higher cation symmetry or longer alkyl moieties induces a higher viscosity, though the viscosity index is dependent more on molecular mass than on symmetry. While a larger cation size generally increases an IL's solubility in non-polar hydrocarbon oils, six-carbon seems to be the critical minimum alkyl chain length for high oil miscibility. Both the two ILs, that are mutually oil miscible, have demonstrated promising lubricating performance at 1.04% treat rate, though the symmetric-cation IL moderately outperformed the asymmetric-cation IL. Characterizations on the tribofilm formed by the best-performing symmetric-cation IL revealed the film thickness, nanostructure, and chemical composition. Results here provide fundamental insights for future molecular design in developing oil-soluble ILs as lubricant additives.
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Advances in engineering of high contrast CARS imaging endoscopes.
Opt Express
PUBLISHED: 11-18-2014
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The translation of CARS imaging towards real time, high resolution, chemically selective endoscopic tissue imaging applications is limited by a lack of sensitivity in CARS scanning probes sufficiently small for incorporation into endoscopes. We have developed here a custom double clad fiber (DCF)-based CARS probe which is designed to suppress the contaminant Four-Wave-Mixing (FWM) background generated within the fiber and integrated it into a fiber based scanning probe head of a few millimeters in diameter. The DCF includes a large mode area (LMA) core as a first means of reducing FWM generation by ~3 dB compared to commercially available, step-index single mode fibers. A micro-fabricated miniature optical filter (MOF) was grown on the distal end of the DCF to block the remaining FWM background from reaching the sample. The resulting probe was used to demonstrate high contrast images of polystyrene beads in the forward-CARS configuration with > 10 dB suppression of the FWM background. In epi-CARS geometry, images exhibited lower contrast due to the leakage of MOF-reflected FWM from the fiber core. Improvements concepts for the fiber probe are proposed for high contrast epi-CARS imaging to enable endoscopic implementation in clinical tissue assessment contexts, particularly in the early detection of endoluminal cancers and in tumor margin assessment.
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TGF-?1, Ghrelin, Neurexin, and Neuroligin are Predictive Biomarkers for Postoperative Prognosis of Laparoscopic Surgery in Children with Hirschsprung Disease.
Cell Biochem. Biophys.
PUBLISHED: 11-17-2014
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The study was set to analyze the predictive values of transforming growth factor ?1 (TGF-?1), Ghrelin, Neurexin, and Neuroligin protein expression on postoperative prognosis of laparoscopic surgery in children with Hirschsprung disease. 281 cases of children with Hirschsprung disease, admitted into Guangdong Women and Children Hospital and Guangzhou women and children's medical center from March 2009 to March 2014, were treated with laparoscopic radical surgery for Hirschsprung disease. They were divided into the good and the poor prognosis groups according to their recuperation and complications. Protein expressions of TGF-?1, Ghrelin, Neurexin, and Neuroligin were prospectively analyzed. The correlations between the expressions of these proteins and the prognosis were analyzed. There were 129 cases of children with poor prognosis, accounting for 45.9 %. There were no significant differences in the expressions of TGF-?1 mRNA and proteins within the group in both the groups (p > 0.05). TGF-?1 mRNA and protein expressions of the poor prognosis group were significantly higher than those of the good prognosis group in each segment of intestine (p < 0.05). Protein detection results manifested that Ghrelin protein expression gradually increased along narrow segment, transitional segment, and expansion segment in both groups. Ghrelin protein expression of the poor prognosis group was significantly lower than that of the good prognosis group in each segment of intestine (p < 0.05). There were significant differences in the protein expressions of Neurexin and Neuroligin within the group. The protein expressions of Neurexin and Neuroligin in expansion segment were the highest. Neurexin and Neuroligin protein expressions of the poor prognosis group were significantly lower than those of the good prognosis group in each segment of intestine (p < 0.05). Increasing expression of TGF-?1 protein, decreasing expressions of Ghrelin, Neurexin, and Neuroligin proteins can induce the loss or dysfunction of ganglion cells in distal intestinal canal, which is closely correlated with the occurrences of adverse prognosis, such as increased intestinal peristalsis recovery time, increased complication rate etc., in children. It has a high value for predicting prognosis of children patients with Hirschsprung disease after surgical intervention.
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Association between process indicators and in-hospital mortality among patients with chronic heart failure in China.
Eur J Public Health
PUBLISHED: 11-15-2014
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Quality indicators for Chinese patients with chronic heart failure (CHF) have been developed. However, little is known about the compliance with quality indicators and the association between process indicators and in-hospital mortality in China.
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Novel scanning electron microscope bulge test technique integrated with loading function.
Rev Sci Instrum
PUBLISHED: 11-03-2014
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Membranes and film-on-substrate structures are critical elements for some devices in electronics industry and for Micro Electro Mechanical Systems devices. These structures are normally at the scale of micrometer or even nanometer. Thus, the measurement for the mechanical property of these membranes poses a challenge over the conventional measurements at macro-scales. In this study, a novel bulge test method is presented for the evaluation of mechanical property of micro thin membranes. Three aspects are discussed in the study: (a) A novel bulge test with a Scanning Electron Microscope system realizing the function of loading and measuring simultaneously; (b) a simplified Digital Image Correlation method for a height measurement; and (c) an imaging distortion correction by the introduction of a scanning Moiré method. Combined with the above techniques, biaxial modulus as well as Young's modulus of the polyimide film can be determined. Besides, a standard tensile test is conducted as an auxiliary experiment to validate the feasibility of the proposed method.
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Ionic liquids composed of phosphonium cations and organophosphate, carboxylate, and sulfonate anions as lubricant antiwear additives.
Langmuir
PUBLISHED: 10-30-2014
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Oil-soluble phosphonium-based ionic liquids (ILs) have recently been reported as potential ashless lubricant additives. This study is to expand the IL chemistry envelope and to achieve fundamental correlations between the ion structures and ILs' physiochemical and tribological properties. Here we present eight ILs containing two different phosphonium cations and seven different anions from three groups: organophosphate, carboxylate, and sulfonate. The oil solubility of ILs seems largely governed by the IL molecule size and structure complexity. When used as oil additives, the ranking of effectiveness in wear protection for the anions are organophosphate > carboxylate > sulfonate. All selected ILs outperformed a commercial ashless antiwear additive. Surface characterization from the top and the cross-section revealed the nanostructures and compositions of the tribo-films formed by the ILs. Some fundamental insights were achieved: branched and long alkyls improve the IL's oil solubility, anions of a phosphonium-phosphate IL contribute most phosphorus in the tribo-film, and carboxylate anions, though free of P, S, N, or halogen, can promote the formation of an antiwear tribo-film.
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The complete mitochondrial genome of the Epinephelus lanceolatus (Perciformes: Serranidae).
Mitochondrial DNA
PUBLISHED: 10-07-2014
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Abstract The complete mitochondrial genome of the Epinephelus lanceolatus was presented in this study. The mitochondrial genome is 16,743?bp long and consists of 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a control region. The gene order and composition of E. lanceolatus mitochondrial genome was similar to that of most other vertebrates. The nucleotide compositions of the light strand are 26.55% of A, 15.02% of C, 29.67% of T and 28.76% of G. With the exception of the NADH dehydrogenase subunit 6 (ND6) and eight tRNA genes, all other mitochondrial genes are encoded on the heavy strand.
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Statistics-based electron Moiré technique: a novel method applied to the characterization of mesoporous structures.
Nanoscale
PUBLISHED: 10-03-2014
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We report a statistics-based electron Moiré method in this study, for the first time, to cope with the highly distorted fringes and to realize the measurement of disordered mesoporous structures. A grey-level co-occurrence matrix is employed to determine the predominant period and the orientation of a randomly distributed Moiré fringe pattern and consequently to obtain the corresponding period/orientation of the test structures. The basic principles, the method descriptions, and the relevant experiments are discussed in detail. Mesoporous alumina films are investigated with the proposed method.
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Mycobacterium smegmatis?BioQ defines a new regulatory network for biotin metabolism.
Mol. Microbiol.
PUBLISHED: 09-28-2014
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Biotin (vitamin H), the sulfur-containing enzyme cofactor, is an essential micronutrient for three domains of life. Given the fact that biotin is an energetically expensive molecule whose de novo biosynthesis demands 20 ATP equivalents each, it is reasonable that bacteria have evolved diversified mechanisms in various microorganisms to tightly control biotin metabolism. Unlike the Escherichia coli?BirA, the prototypical bi-functional version of biotin protein ligase (BPL) in that it acts as a repressor for biotin biosynthesis pathway, the BirA protein of Mycobacterium smegmatis (M. smegmatis), a closely relative of the tuberculosis-causing pathogen, Mycobacterium tuberculosis, lacked the DNA-binding activity. It raised a possibility that an alternative new regulator might be present to compensate the loss of regulatory function. Here we report that this is the case. Genomic context analyses of M. smegmatis detected a newly identified BioQ homolog classified into the TetR family of transcription factor and its recognizable palindromes. The?M. smegmatis?BioQ protein was overexpressed and purified to homogeneity. Size-exclusion chromatography combined with chemical cross-linking studies demonstrated that the BioQ protein had a propensity to dimerize. The promoters of bioFD and bioQ/B were mapped using 5'-RACE. Electrophoretic mobility shift assays revealed that BioQ binds specifically to the promoter regions of bioFD and bioQ/B. Further DNase I foot-printing elucidated the BioQ-binding palindromes. Site-directed mutagenesis suggested the important residues critical for BioQ/DNA binding. The isogenic mutant of bioQ (?bioQ) was generated using the approach of homologous recombination. The in vivo data from the real-time qPCR combined with the lacZ transcriptional fusion experiments proved that removal of bioQ gave significant increment with expression of bio operons. Also, expression of bio operons were repressed by exogenous addition of biotin, and this repression seemed to depend on the presence of BioQ protein. Thereby, we believed that?M. smegmatis?BioQ is not only a negative auto-regulator but also a repressor for bioFD and bioB operons involved in the biotin biosynthesis pathway. Collectively, this finding defined the two-protein paradigm of BirA and BioQ, representing a new mechanism for bacterial biotin metabolism.
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Microbacterium petrolearium sp. nov., isolated from oil-contaminated water sample from Dagang oilfield in China.
Int. J. Syst. Evol. Microbiol.
PUBLISHED: 09-26-2014
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A Gram-positive, rod-shaped aerobic bacterium, designated strain LAM0410(T)?was isolated from oil contaminated water sample from Dagang Oilfield, China. The temperature and pH ranges for growth were 4 °C to 50 °C and 4.4 to 12.0, respectively. The strain did not need NaCl for growth but could tolerate up to 12% concentration. Cell wall hydrolysates from the isolate showed that the diamino acids was ornithine. The cell wall sugars contains ribose and galactose. The glycan moiety of the cell wall contained N-glycolyl residues. The major respiratory quinones were MK-10, MK-11 and MK-12. The major polar lipids were diphosphatidyglycerol, phosphatidylglycerol and nine unknown glycolipids. The major fatty acids were anteiso-C15:0, anteiso-C17:0, and iso-C16:0. The 16S rRNA gene sequence analysis indicated that the isolate belonged to the genus Microbacterium and closely related to M. sediminis MCCC 1A06153(T) and M. murale DSM22178(T) with 97.5% and 97.4% sequence similarity, the DNA-DNA hybridization values were 33.1±3.4% and 21.8±1.6% , respectively. The DNA G+C content was 67.4 mol % as determined by Tm method. Based on its phenotypic and genotypic properties, strain LAM0410(T) was suggested to represent a novel species of the genus Microbacterium, for which the name Microbacterium petrolearium sp. nov., is proposed, the type strain is LAM0410(T) (=ACCC 00719(T) = JCM 19612(T) ).
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Clostridium huakuii sp. nov., a novel anaerobic acetogenic bacterium isolated from methanogenic consortia.
Int. J. Syst. Evol. Microbiol.
PUBLISHED: 09-19-2014
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A Gram-staining-positive, spore-forming, obligate anaerobic acetogenic bacterium, designated LAM1030 (T), was isolated from methanogenic consortia enriched from biogas slurry collected from the large-scale anaerobic digester of Modern Farming Corporation in Hebei Province, China. Cells of strain LAM1030(T) were motile, straight or spiral-rod-shaped. Strain LAM1030(T) could utilize glucose, fructose, maltose, galacatose, lactose, sucrose, cellobiose?mannitol, pyruvate, succinic acid, tryptophan as sole carbon source. Acetic acid, isovaleric acid and butanoic acid were the main productions of glucose fermentation. Sodium sulfite was used as electron acceptor. Growth of strain LAM1030(T) was completely inhibited by the addition of 20 ?g/ml of ampicillin, tetracycline, gentamicin and erythromycin. The main polar lipids of strain LAM1030(T) were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and eleven unknown glycolipids and two unknown phospholipids. No respiratory quinone was detected. The major fatty acids of strain LAM1030(T) were C16:0 (21.1%), C14:0 (10.3%) and iso-C15:0 (6.6%). The analysis on the 16S rRNA gene sequence indicated that strain LAM1030(T) belonged to the genus Clostridium and was most closely related to C. subterminale DSM 6970(T), C. thiosulfatireducens DSM 13105(T) and C. sulfidigenes DSM 18982(T), with 97.0%, 96.9% and 96.8% similarity, respectively. The G+C content of the genomic DNA of strain LAM1030(T) was 31.2±0.3 mol%. On the basis of its phenotypic, phylogenetic and chemotaxonomic characterization, strain LAM1030(T) was suggested to represent a novel species of the genus Clostridium , for which the name Clostridium huakuii sp. nov. is proposed. The type strain is LAM1030(T) (=ACCC 00698(T) = JCM 19186(T)).
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[Evaluation of nutrient level and its factors of breast milk in Shenzhen City].
Wei Sheng Yan Jiu
PUBLISHED: 09-10-2014
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To investigate the nutrient level for Fat and Nutrient Elements (Ca, K, Na, Mg, Fe and Zn) in Breast Milk and its factors in Shenzhen, China. Eventually we can evaluate the nutrient study for local infants and provide a more reasonable basis for infants breast-feeding.
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MiR-198 represses tumor growth and metastasis in colorectal cancer by targeting fucosyl transferase 8.
Sci Rep
PUBLISHED: 09-01-2014
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In this study we investigated the biological role and mechanism of miR-198 in colorectal carcinoma (CRC). MiR-198 expression was shown to exhibit a strongly negative correlation with lymph node invasion, distant metastasis and patient survival in examinations of colorectal cancer tissues and paired normal colorectal mucosa tissues. fucosyl transferase 8 (FUT8) was identified as a potential target of miR-198 in bioinformatics analysis and luciferase reporter assays. Overexpression of miR-198 in CRC cell lines decreased FUT8 levels as shown by immunofluorescence analysis, and inhibited cell proliferation, migration, and invasion. These anti-tumor phenotypes were rescued by reconstitution of FUT8 expression. Furthermore, miR-198 was shown to target the 3'UTR of FUT8 directly to downregulate FUT8 expression at both mRNA and protein levels in qRT-PCR and Western blot analyses, respectively. In vivo, restoration of miR-198 significantly inhibited xenograft growth and invasion of CRC tumors in nude mice. Therefore, it could be concluded that miR-198 suppresses the proliferation and invasion of CRC by directly targeting FUT8.
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Nickel-cobalt bimetallic anode catalysts for direct urea fuel cell.
Sci Rep
PUBLISHED: 08-29-2014
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Nickel is an ideal non-noble metal anode catalyst for direct urea fuel cell (DUFC) due to its high activity. However, there exists a large overpotential toward urea electrooxidation. Herein, NiCo/C bimetallic nanoparticles were prepared with various Co contents (0, 10, 20, 30 and 40 wt%) to improve the activity. The best Co ratio was 10% in the aspect of cell performance, with a maximum power density of 1.57 mW cm(-2) when 0.33 M urea was used as fuel, O2 as oxidant at 60 °C. The effects of temperature and urea concentration on DUFC performance were investigated. Besides, direct urine fuel cell reaches a maximum power density of 0.19 mW cm(-2) with an open circuit voltage of 0.38 V at 60 °C.
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Remediation of chromium-slag leakage with electricity cogeneration via a urea-Cr(VI) cell.
Sci Rep
PUBLISHED: 08-29-2014
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Chromium pollution has been historically widespread throughout the world. Most available remediation technologies often require energy consumption. This study is aimed to develop electrochemical remediation for Cr(VI) in chromium-slag leakage with self-generated electricity. Dynamic leaching experiments of chromium-slag samples were conducted to survey the release and leaching behavior of Cr(VI). Based on previous work, a unique urea-Cr(VI) was designed, in which urea was employed as the fuel and Cr(VI) from the leakage of the dichromate slag served as the oxidant. Furthermore, the electrochemical results showed that the removal percent of Cr(VI) was more than 96% after 18 h with the leakage Cr(VI) concentration of 2.69 mM. The open circuit potential (OCP) varied in the range of 1.56 ~ 1.59 V under different initial Cr(VI) leakage concentrations. The approach explores the feasibility of the promising technique without the need of energy input for simultaneous chromium-slag remediation and generation of electricity.
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Chronic Copper Exposure Causes Spatial Memory Impairment, Selective Loss of Hippocampal Synaptic Proteins, and Activation of PKR/eIF2? Pathway in Mice.
J. Alzheimers Dis.
PUBLISHED: 08-26-2014
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Copper is an essential element for human growth and development; however, excessive intake of copper could contribute to neurotoxicity. Here we show that chronic exposure to copper in drinking water impaired spatial memory with simultaneous selective loss of hippocampal pre-synaptic protein synapsin 1, and post-synaptic density protein (PSD)-93/95 in mice. Copper exposure was shown to elevate the levels of nitrotyrosine and 8-hydroxydeoxyguanosine (8-OHdG) in hippocampus, two markers of oxidative stress. Concurrently, we also found that copper exposure activated double stranded RNA-dependent protein kinase (PKR) as evidenced by increased ratio of phosphorylated PKR at Thr451 and total PKR and increased the phosphorylation of its downstream signaling molecule eukaryotic initiation factor 2? (eIF2?) at Ser51 in hippocampus. Consistent with activation of PKR/eIF2? signaling pathway which was shown to mediate synaptic deficit and cognitive impairment, the levels of activating transcription factor 4 (ATF-4), a downstream signaling molecule of eIF2? and a repressor of CREB-mediated gene expression, were significantly increased, while the activity of cAMP response elements binding protein (CREB) was inactivated as suggested by decreased phosphorylation of CREB at Ser133 by copper exposure. In addition, the expression of the pro-apoptotic target molecule C/EBP homology protein (CHOP) of ATF-4 was upregulated and hippocampal neuronal apoptosis was induced by copper exposure. Taken together, we propose that chronic copper exposure might cause spatial memory impairment, selective loss of synaptic proteins, and neuronal apoptosis through the mechanisms involving activation of PKR/eIF2? signaling pathway.
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A cell-surface-anchored ratiometric fluorescent probe for extracellular pH sensing.
ACS Appl Mater Interfaces
PUBLISHED: 08-21-2014
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Accurate sensing of the extracellular pH is a very important yet challenging task in biological and clinical applications. This paper describes the development of an amphiphilic lipid-DNA molecule as a simple yet useful cell-surface-anchored ratiometric fluorescent probe for extracellular pH sensing. The lipid-DNA probe, which consists of a hydrophobic diacyllipid tail and a hydrophilic DNA strand, is modified with two fluorescent dyes; one is pH-sensitive as pH indicator and the other is pH-insensitive as an internal reference. The lipid-DNA probe showed sensitive and reversible response to pH change in the range of 6.0-8.0, which is suitable for most extracellular studies. In addition, based on simple hydrophobic interactions with the cell membrane, the lipid-DNA probe can be easily anchored on the cell surface with negligible cytotoxicity, excellent stability, and unique ratiometric readout, thus ensuring its accurate sensing of extracellular pH. Finally, this lipid-DNA-based ratiometric pH indicator was successfully used for extracellular pH sensing of cells in 3D culture environment, demonstrating the potential applications of the sensor in biological and medical studies.
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Percutaneous transluminal angioplasty for symptomatic pulmonary stenosis in Takayasu arteritis.
J. Rheumatol.
PUBLISHED: 08-15-2014
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The aim of this study was to evaluate the safety and efficacy of percutaneous transluminal angioplasty (PTA) for symptomatic pulmonary stenosis in Takayasu arteritis (TA).
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NR2B overexpression leads to the enhancement of specific protein phosphorylation in the brain.
Brain Res.
PUBLISHED: 08-13-2014
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n-methyl-d-aspartate receptors (NMDARs) are highly expressed in the central nervous system (CNS) including the cerebral cortex, and it has been found that they contribute significantly to the processes of learning and memory. Dysfunctions of NMDARs are implicated in many neurological disorders. To further investigate the specific role of the NR2B subunit of NMDARs in brain functions, we have examined differences in gene expression in the cerebral cortex between NR2B transgenic mice and their wild-type littermates using the DNA microarray. Total of 179 differentially expressed genes were identified, including genes involved in ion channel activity and/or neurotransmission, signal transduction, structure/cytoskeleton, transcription, and hormone/growth factor activity. Signal pathway analysis has indicated that multiple pathways were involved in this process, especially the Mitogen-activated protein kinases/Extracellular signal-regulated kinases (MAPK/ERK) pathway. The phosphorylation levels of ERK and cAMP response element-binding protein (CREB), and the mRNA levels of CREB target genes (C-Fos and Nr4a1) were significantly upregulated in the cerebral cortices of NR2B transgenic mice compared to their wild-type littermates. Our study suggested that a chronic increase of NMDARs activation by NR2B overexpression in the forebrain may enhance the protein serine/threonine phosphorylation levels of MAPK/ERK-CREB and thereby regulated their signaling pathway.
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Au@Pt Nanoparticle Encapsulated Target-Responsive Hydrogel with Volumetric Bar-Chart Chip Readout for Quantitative Point-of-Care Testing.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 08-11-2014
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Point-of-care testing (POCT) with the advantages of speed, simplicity, portability, and low cost is critical for the measurement of analytes in a variety of environments where access to laboratory infrastructure is lacking. While qualitative POCTs are widely available, quantitative POCTs present significant challenges. Here we describe a novel method that integrates an Au core/Pt shell nanoparticle (Au@PtNP) encapsulated target-responsive hydrogel with a volumetric bar-chart chip (V-Chip) for quantitative POCT. Upon target introduction, the hydrogel immediately dissolves and releases Au@PtNPs, which can efficiently catalyze the decomposition of H2 O2 to generate a large volume of O2 to move of an ink bar in the V-Chip. The concentration of the target introduced can be visually quantified by reading the traveling distance of the ink bar. This method has the potential to be used for portable and quantitative detection of a wide range of targets without any external instrument.
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From memory to prospection: what are the overlapping and the distinct components between remembering and imagining?
Front Psychol
PUBLISHED: 08-06-2014
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Reflecting on past events and reflecting on future events are two fundamentally different processes, each traveling in the opposite direction of the other through conceptual time. But what we are able to imagine seems to be constrained by what we have previously experienced, suggesting a close link between memory and prospection. Recent theories suggest that recalling the past lies at the core of imagining and planning for the future. The existence of this link is supported by evidence gathered from neuroimaging, lesion, and developmental studies. Yet it is not clear exactly how the novel episodes people construct in their sense of the future develop out of their historical memories. There must be intermediary processes that utilize memory as a basis on which to generate future oriented thinking. Here, we review studies on goal-directed processing, associative learning, cognitive control, and creativity and link them with research on prospection. We suggest that memory cooperates with additional functions like goal-directed learning to construct and simulate novel events, especially self-referential events. The coupling between memory-related hippocampus and other brain regions may underlie such memory-based prospection. Abnormalities in this constructive process may contribute to mental disorders such as schizophrenia.
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In vitro and in vivo modifications of recombinant and human IgG antibodies.
MAbs
PUBLISHED: 08-06-2014
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Tremendous knowledge has been gained in the understanding of various modifications of IgG antibodies, driven mainly by the fact that antibodies are one of the most important groups of therapeutic molecules and because of the development of advanced analytical techniques. Recombinant monoclonal antibody (mAb) therapeutics expressed in mammalian cell lines and endogenous IgG molecules secreted by B cells in the human body share some modifications, but each have some unique modifications. Modifications that are common to recombinant mAb and endogenous IgG molecules are considered to pose a lower risk of immunogenicity. On the other hand, modifications that are unique to recombinant mAbs could potentially pose higher risk. The focus of this review is the comparison of frequently observed modifications of recombinant monoclonal antibodies to those of endogenous IgG molecules.
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Heterozygous deletion of ventral anterior homeobox (vax1) causes subfertility in mice.
Endocrinology
PUBLISHED: 07-25-2014
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The known genetic causes of idiopathic hypogonadotropic hypogonadism (IHH) are often associated with the loss of GnRH neurons, leading to the disruption of the hypothalamic pituitary gonadal axis and subfertility. The majority of IHH cases have unknown origins and likely arise from compound mutations in more than one gene. Here we identify the homeodomain transcription factor ventral anterior homeobox1 (Vax1) as a potential genetic contributor to polygenic IHH. Although otherwise healthy, male and female Vax1 heterozygous (HET) mice are subfertile, indicating dosage sensitivity for the Vax1 allele. Although Vax1 mRNA is expressed in the pituitary, hypothalamus, and testis, we did not detect Vax1 mRNA in the sperm, ovary, or isolated pituitary gonadotropes. Whereas Vax1 HET females produced normal numbers of superovulated oocytes, corpora lutea numbers were reduced along with a slight increase in circulating basal LH and estrogen. The subfertility originated in the hypothalamus in which kisspeptin and GnRH transcripts were altered along with a substantial reduction of GnRH neuron number. Although the pituitary responded normally to a GnRH challenge, diestrus females had reduced LH? and FSH? in diestrus. Furthermore, Vax1 HET males had reduced GnRH mRNA and neuron numbers, whereas the pituitary had normal transcript levels and response to GnRH. Interestingly, the Vax1 HET males had an 88% reduction of motile sperm. Taken together, our data suggest that Vax1 HET subfertility originates in the hypothalamus by disrupting the hypothalamic-pituitary-gonadal axis. In addition, male subfertility may also be due to an unknown effect of Vax1 in the testis.
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Suppression of AKT expression by miR-153 produced anti-tumor activity in lung cancer.
Int. J. Cancer
PUBLISHED: 07-22-2014
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Lung cancer is one of the leading causes of cancer death worldwide. microRNAs have been shown to be a novel class of regulators in lung cancer. Here, we explored the role of miR-153 in the pathogenesis of lung cancer and its therapeutic potential. miR-153 was significantly decreased in lung cancer tissues than the adjacent tissues. The protein and mRNA levels of protein kinase B (AKT), which were shown to promote tumor growth, were both increased in lung cancer tissues than adjacent tissues. Overexpression of miR-153 significantly inhibited AKT protein expression, which were abrogated by co-transfection of AMO-153, the specific inhibitor of miR-153. Luciferase assay showed that transfection of miR-153 markedly suppressed the fluorescent intensity of chimeric vectors carrying the 3'UTR of AKT1, while produced no effect on the mutant construct, indicating that AKT is regulated by miR-153. Overexpression of miR-153 significantly inhibited the proliferation and migration, and promoted apoptosis of cultured lung cancer cells in vitro, and suppressed the growth of xenograft tumors in vivo. Interestingly, lung cancer cells with lower endogenous miR-153 expression are more sensitive to ectopic overexpressed miR-153. The IC50 of miR-153 on lung cancer cells is positive correlated with the endogenous miR-153 level, while negative correlated with AKT level. Knockdown of AKT expression suppressed lung cancer cell proliferation. In summary, miR-153 exerted anti-tumor activity in lung cancer by targeting on AKT. The sensitivity of lung cancer cells to miR-153 is determined by its endogenous miR-153 level.
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Transradial renal denervation for the treatment of resistant hypertension.
J Invasive Cardiol
PUBLISHED: 07-05-2014
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As a novel device-based approach targeting the renal sympathetic nerves, renal denervation has been shown to be effective and safe in reducing blood pressure. The femoral artery is currently the most common access site for this procedure due to catheter profile and length limitations that restrict the use of radial access. The purpose of this study was to evaluate technical feasibility and short-term outcomes of transradial renal denervation by a longer radiofrequency ablation catheter (155 cm; AngioCare).
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Characteristics of demyelinating Charcot-Marie-Tooth disease with concurrent diabetes mellitus.
Int J Clin Exp Pathol
PUBLISHED: 06-15-2014
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Charcot-Marie-Tooth disease (CMT) is the most common type of inherited peripheral neuropathy and has a high degree of genetic heterogeneity. CMT with concurrent diabetes mellitus (DM) is rare. The purpose of this study is to explore the genetic, clinical and pathological characteristics of the patients with CMT and concurrent DM.
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CREG1 promotes angiogenesis and neovascularization.
Front Biosci (Landmark Ed)
PUBLISHED: 06-05-2014
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Angiogenesis has long been considered as an important strategy for ischemic injury. It has been reported that cellular repressor of E1A-stimulated genes (CREG1) promotes human umbilical vein endothelial cell (HUVEC) proliferation, migration, and protects endothelial cell (EC) from apoptosis. However, its potential effect on angiogenesis remains undefined. In the present study, we investigated the role and mechanisms of CREG1 in promoting angiogenesis. We found that adenovirus-transduced CREG1 expression in HUVECs increases EC tube formation in matrigel and promotes neovascularization in matrigel plugs grafted into wild type mice. In addition, adenoviral CREG1 expression enhances filopodia formation, which is accompanied by increased expression of integrin-linked kinase (ILK) and activation of its downstream effector Cdc42. Hindlimb perfusion was significantly reduced after femoral artery ligation in CREG1 heterozygous knockout mice. Finally, adenoviral CREG1 was injected intramuscularly in gastrochemius and partially restores ischemic hindlimb perfusion. Our results demonstrated that CREG1 increases EC filopodia formation and vascular assembly via ILK-Cdc42 activation and promotes neovascularization, which might be a therapeutic target for ischemic injury.
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Solvent extraction of lanthanides and yttrium from aqueous solution with methylimidazole in an ionic liquid.
Dalton Trans
PUBLISHED: 05-23-2014
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1-Methylimidazole (1-MIM) and 2-methylimidazole (2-MIM) are miscible in water and imidazolium based ionic liquids (ILs), and can coordinate with soft metal ions. This paper reports a novel solvent extraction process for trivalent lanthanides and yttrium from aqueous solutions into ILs, which was promoted by a hydrophilic 1-MIM or 2-MIM. Slope analysis confirmed that MIM in ILs formed a 1?:?1 complex with La(3+) and Y(3+) and a 1?:?4 complex with Eu(3+) and Lu(3+), depending on the atomic number of the metal and the metal-ligand interactions that have been characterized by FTIR spectroscopy and ESI-MS. The effect of nitrate concentration on the extraction of lanthanides with 1-MIM in ILs was analysed. It indicated that nitrate anions were involved in the extraction process. Under the same conditions, the extraction of lanthanides with MIM into n-pentanol was carried out. The extractability was by far lower than that obtained in ILs. Both cationic exchange and neutral solvation mechanisms occurred in ILs and only the neutral solvation mechanism occurred in n-pentanol, which were demonstrated by the extraction tests and the structure of extracted species determined by ESI-MS. The competitive extraction in ILs showed good selectivity for lanthanides compared to alkali metals and alkaline earth cations. After extraction, lanthanides could be stripped very easily from the ionic liquid phase with dilute nitric acid. From the temperature dependence data, the thermodynamic parameter values (?H, ?S and ?G) were calculated. The results indicated that the extraction reactions were spontaneous and went through an endothermic process.
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Lysinibacillus halotolerans sp. nov., isolated from saline-alkaline soil.
Int. J. Syst. Evol. Microbiol.
PUBLISHED: 05-09-2014
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A novel aerobic, halotolerant bacterium, designated strain LAM612(T), was isolated from saline-alkaline soil samples from Lingxian County, Shandong Province, China. Cells of strain LAM612(T) were Gram-reaction-positive, endospore-forming, motile and rod-shaped. The optimal temperature and pH for growth were 35 °C and pH 6.0, respectively. Strain LAM612(T) could grow in the presence of up to 10% (w/v) NaCl. The genomic DNA G+C conten was 36.4 mol% as detected by the T(m) method. Comparative analysis of 16S rRNA gene sequences revealed that LAM612(T) was closely related to Lysinibacillus sinduriensis KACC 16611(T) (98.0%), L. chungkukjangi KACC 16626(T) (97.5%), L. massiliensis KCTC 13178(T) (97.4%), L. xylanilyticus KACC 15113(T) (97.2%), L. macroides DSM 54(T) (97.0%) and L. manganicus DSM 26584(T) (96.5%). The DNA-DNA hybridization values between strain LAM612(T) and its closest relatives ranged from 20.6% to 41.9%. The major fatty acids of strain LAM612(T) were iso-C(15?:?0) (40.8%), iso-C(16?:?0) (15.2%) and anteiso-C(15?:?0) (10.8%). The cell-wall peptidoglycan content was A4? (L-Lys-D-Asp). The predominant menaquinone was MK-7 and the main polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unknown phospholipids, five unknown glycolipids and an unknown lipid. Based on the DNA-DNA hybridization results and phenotypic, phylogenetic and chemotaxonomic properties, strain LAM612(T) could be distinguished from the recognized species of the genus Lysinibacillus, and was suggested to represent a novel species of this genus, for which the name Lysinibacillus halotolerans sp. nov. is proposed. The type strain is LAM612(T) (?=?ACCC 00718(T)?=?JCM 19611(T)).
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Understory vegetation leads to changes in soil acidity and in microbial communities 27years after reforestation.
Sci. Total Environ.
PUBLISHED: 05-06-2014
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Experiments with potted plants and removed understories have indicated that understory vegetation often affects the chemical and microbial properties of soil. In this study, we examined the mechanism and extent of the influence of understory vegetation on the chemical and microbial properties of soil in plantation forests. The relationships between the vegetational structure (diversity for different functional layers, aboveground biomass of understory vegetation, and species number) and soil properties (pH, microbial community structure, and levels of soil organic carbon, total nitrogen, and inorganic nitrogen) were analyzed across six reforestation types (three pure needleleaf forests, a needle-broadleaf mixed forest, a broadleaf forest, and a shrubland). Twenty-seven years after reforestation, soil pH significantly decreased by an average of 0.95 across reforestation types. Soil pH was positively correlated with the aboveground biomass of the understory. The levels of total, bacterial, and fungal phospholipid fatty acids, and the fungal:bacterial ratios were similar in the shrubland and the broadleaf forest. Both the aboveground biomass of the understory and the diversity of the tree layer positively influenced the fungal:bacterial ratio. Improving the aboveground biomass of the understory could alleviate soil acidification. An increase in the aboveground biomass of the understory, rather than in understory diversity, enhanced the functional traits of the soil microbial communities. The replacement of pure plantations with mixed-species stands, as well as the enhancement of understory recruitment, can improve the ecological functions of a plantation, as measured by the alleviation of soil acidification and increased fungal dominance.
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Long-term clinical outcomes of selective segmental transforaminal lumbar interbody fusion combined with posterior spinal fusion for degenerative lumbar scoliosis.
ANZ J Surg
PUBLISHED: 05-03-2014
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The purpose of the current study was to investigate the long-term clinical outcomes of this technique for degenerative scoliosis (DS).
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Sex differences in blood pressure control in SHR: lack of a role for EETs.
Physiol Rep
PUBLISHED: 05-01-2014
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The mechanisms responsible for the gender difference in blood pressure (BP) in humans are not clear. Over the past several years we have studied the spontaneously hypertensive rat (SHR) as a model of sex differences in BP control. In the present study, we tested the hypothesis that renal vascular and microsomal epoxyeicosatrienoic acid (EET) levels are higher in females than males, and increasing vascular EETs by blocking epoxide hydrolase with AUDA will reduce BP more in males than females. Renal vascular and microsomal EETs were higher in female SHR than males. Mean arterial pressure (MAP by telemetry) was higher in males than females during the baseline period of 6 days, and although the epoxide hydrolase inhibitor, AUDA, given for 10 days increased renal microvascular EETs in both groups, AUDA did not affect MAP in either group. These data suggest that EETs do not contribute to the sex differences in hypertension in young SHR.
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A novel integrated tension-compression design for a mini split Hopkinson bar apparatus.
Rev Sci Instrum
PUBLISHED: 04-03-2014
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A miniature integrated Split Hopkinson Bar (SHB) apparatus based on an innovative three-loading bar technique and a multi-stage electromagnetic driving technique was developed for both impact compression and tensile tests. The design principles of these techniques and the whole structure of this new device are discussed in detail. Compared to the traditional SHB apparatus which has a single-function, this new device can realize the integration of compression and tensile tests. Furthermore, due to the application of the electromagnetic driving technique, the whole structure of the SHB apparatus can be miniaturized with good reproducibility, reliability, and no noise, making it easier to move to different locations without the need for heavy gas launching systems used for some specialist tests. Under both impact compression and tensile conditions, a series of verification experiments were carried out on 2A12 aluminum alloy, proving that the new apparatus can conduct impact tension and compression tests for small specimen with high accuracy and reliability. The dynamic behavior of electrodeposited nickel fabricated by micromachining was investigated at a high strain rate of 1.2 × 10(4) s(-1) using this new setup, the obtained results indicating that the Lithographie Galanoformung Abformung (LIGA) deposited nickel is very sensitive to strain rate.
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A diazirine-based photoaffinity probe for facile and efficient aptamer-protein covalent conjugation.
Chem. Commun. (Camb.)
PUBLISHED: 04-02-2014
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A photo-reactive functional labelling reagent, diazirine phosphoramidite, was designed and synthesized for easy and flexible site-specific labelling of oligonucleotides with the diazirine moiety. The new reagent allows facile photo-crosslinking of oligonucleotide with its interacting partner for a variety of applications, including tertiary structure determination, molecular interaction study and biomarker discovery.
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Streptococcus suis infection: an emerging/reemerging challenge of bacterial infectious diseases?
Virulence
PUBLISHED: 03-25-2014
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Streptococcus suis (S. suis) is a family of pathogenic gram-positive bacterial strains that represents a primary health problem in the swine industry worldwide. S. suis is also an emerging zoonotic pathogen that causes severe human infections clinically featuring with varied diseases/syndromes (such as meningitis, septicemia, and arthritis). Over the past few decades, continued efforts have made significant progress toward better understanding this zoonotic infectious entity, contributing in part to the elucidation of the molecular mechanism underlying its high pathogenicity. This review is aimed at presenting an updated overview of this pathogen from the perspective of molecular epidemiology, clinical diagnosis and typing, virulence mechanism, and protective antigens contributing to its zoonosis.
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Multi-Enhanced-Phonon Scattering Modes in Ln-Me-A Sites co-substituted LnMeA11O19 Ceramics.
Sci Rep
PUBLISHED: 03-21-2014
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Authors reported an effective path to decrease the thermal conductivity while to increase the coefficient of thermal expansion, thus enhancing the thermo-physical properties of the LnMeA11O19-type magnetoplumbite LaMgAl11O19 by simultaneously substituting La(3+), Mg(2+) and Al(3+) ions with large ionic radius Ba(2+), Zn(2+) and Ti(4+), respectively. The mechanism behind the lowered thermal conductivity was mainly due to the multi-enhanced-phonon scattering modes in Ln-Me-A sites co-substituted LnMeA11O19 ceramics. These modes involve the following four aspects, namely, point defect mechanism, the intrinsic scattering in the complex crystal cell and materials with stepped surface to localize phonon vibrational modes, as well as nano-platelet-like structure to incorporate additional grain boundary scattering. This study provides novel thoughts for promising candidate materials of even lower thermal conductivity for the next generation thermal barrier coatings.
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A new ?-galactosidase from thermoacidophilic Alicyclobacillus sp. A4 with wide acceptor specificity for transglycosylation.
Appl. Biochem. Biotechnol.
PUBLISHED: 03-14-2014
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An ?-galactosidase gene (gal36A4) of glycosyl hydrolase family 36 was identified in the genome of Alicyclobacillus sp. A4. It contains an ORF of 2,187 bp and encodes a polypeptide of 728 amino acids with a calculated molecular mass of 82.6 kDa. Deduced Gal36A4 shows the typical GH36 organization of three domains--the N-terminal ?-sheets, the catalytic (?/?)8-barrels, and the C-terminal antiparallel ?-sheet. The gene product was produced in Escherichia coli and showed both hydrolysis and transglycosylation activities. The optimal pH for hydrolysis activity was 6.0, and a stable pH range of 5.0-11.0 was found. The enzyme had a temperature optimum of 60 °C. It is specific for ?-1,6-glycosidic linkages and had a K m value of 1.45 mM toward pNPGal. When using melibiose as both donor and acceptor of galactose, Gal36A4 showed the transfer ratio of 23.25 % at 96 h. With respect to acceptor specificity, all tested monosaccharides, disaccharides, and oligosaccharides except for D-xylose and L-arabinose were good acceptors for transglycosylation. Thus, Gal36A4 may find diverse applications in industrial fields, especially in the food industry.
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One-year outcomes of percutaneous renal denervation for the treatment of resistant hypertension: the first Chinese experience.
Chin. Med. J.
PUBLISHED: 03-14-2014
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As a novel device-based approach targeting the renal sympathetic nerves, percutaneous renal denervation (RDN) has been shown to be effective and safe for reducing blood pressure. However, while considerable data on RDN have been obtained from Western populations, there is limited findings from East Asian populations. The purpose of this study was to evaluate one-year outcomes of RDN for the treatment of resistant hypertension in Chinese patients.
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Expression and characterization of hyperthermotolerant xylanases, SyXyn11P and SyXyn11E, in Pichia pastoris and Escherichia coli.
Appl. Biochem. Biotechnol.
PUBLISHED: 02-06-2014
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Both Syxyn11P and Syxyn11E, two codon-optimized genes encoding glycoside hydrolase (GH) family 11 hyperthermotolerant xylanases (designated SyXyn11P and SyXyn11E), were synthesized and inserted into pPIC9K(M) and pET-28a(+) vectors, respectively. The resulting recombinant expression vectors, pPIC9K(M)-Syxyn11P and pET-28a(+)-Syxyn11E, were transformed into Pichia pastoris GS115 and Escherichia coli BL21, respectively. The maximum activities of two recombinant xylanases (reSyXyn11P and reSyXyn11E) expressed in P. pastoris and E. coli reached 30.9 and 17.8 U/ml, respectively. The purified reSyXyn11P and reSyXyn11E displayed the same pH optimum at 6.5 and pH stability at a broad range of 4.5-9.0. The temperature optimum and stability of reSyXyn11P were 85 and 80 °C, higher than those of reSyXyn11E, respectively. Their activities were not significantly affected by metal ions tested and EDTA, but strongly inhibited by Mn(2+) and Ag(+). The K m and V max of reSyXyn11P toward birchwood xylan were 4.3 mg/ml and 694.6 U/mg, whose K m was close to that (4.8 mg/ml), but whose V max was much higher than that (205.6 U/mg) of reSyXyn11E. High-performance liquid chromatography analysis indicated that xylobiose and xylotriose as the major products were excised from insoluble corncob xylan by reSyXyn11P.
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The ?-galactosidase (BgaC) of the zoonotic pathogen Streptococcus suis is a surface protein without the involvement of bacterial virulence.
Sci Rep
PUBLISHED: 01-30-2014
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Streptococcal pathogens have evolved to express exoglycosidases, one of which is BgaC ?-galactosidase, to deglycosidate host surface glycolconjucates with exposure of the polysaccharide receptor for bacterial adherence. The paradigm BgaC protein is the bgaC product of Streptococcus, a bacterial surface-exposed ?-galactosidase. Here we report the functional definition of the BgaC homologue from an epidemic Chinese strain 05ZYH33 of the zoonotic pathogen Streptococcus suis. Bioinformatics analyses revealed that S. suis BgaC shared the conserved active sites (W240, W243 and Y454). The recombinant BgaC protein of S. suis was purified to homogeneity. Enzymatic assays confirmed its activity of ?-galactosidase. Also, the hydrolysis activity was found to be region-specific and sugar-specific for the Gal ?-1,3-GlcNAc moiety of oligosaccharides. Flow cytometry analyses combined with immune electron microscopy demonstrated that S. suis BgaC is an atypical surface-anchored protein in that it lacks the "LPXTG" motif for typical surface proteins. Integrative evidence from cell lines and mice-based experiments showed that an inactivation of bgaC does not significantly impair the ability of neither adherence nor anti-phagocytosis, and consequently failed to attenuate bacterial virulence, which is somewhat similar to the scenario seen with S. pneumoniae. Therefore we concluded that S. suis BgaC is an atypical surface-exposed protein without the involvement of bacterial virulence.
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Small-sized PdCu nanocapsules on 3D graphene for high-performance ethanol oxidation.
Nanoscale
PUBLISHED: 01-27-2014
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A one-pot solvothermal process has been developed for direct preparation of PdCu nanocapsules (with a size of ca. 10 nm) on three-dimensional (3D) graphene. Due to the 3D pore-rich network of graphene and the unique hollow structure of PdCu nanocapsules with a wall thickness of ca. 3 nm, the newly-prepared PdCu/3D graphene hybrids activated electrochemically have great electrocatalytic activity towards ethanol oxidation in alkaline media, much better than single-phase Pd and commercial E-TEK 20% Pt/C catalysts promising for application in direct ethanol fuel cells.
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G-quadruplex DNA biosensor for sensitive visible detection of genetically modified food.
Talanta
PUBLISHED: 01-24-2014
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In this paper, a novel label-free G-quadruplex DNAzyme sensor has been proposed for colorimetric identification of GMO using CaMV 35S promoter sequence as the target. The binary probes can fold into G-quadruplex structure in the presence of DNA-T (Target DNA) and then combine with hemin to form a DNAzyme resembling horseradish peroxidase. The detection system consists of two G-rich probes with 2:2 split mode by using the absorbance and color of ABTS(2-) as signal reporter. Upon the addition of a target sequence, two probes both hybridize with target and then their G-rich sequences combine to form a G-quadruplex DNAzyme, and the DNAzyme can catalyze the reaction of ABTS(2-) with H2O2. Then the linear range is from 0.05 to 0.5 ?M while detection limit is 5nM. These results demonstrate that the proposed G-quadruplex DNAzyme method could be used as a simple, sensitive and cost-effective approach for assays of GMO.
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Three-phase catalytic system of H2O, ionic liquid, and VOPO4-SiO2 solid acid for conversion of fructose to 5-hydroxymethylfurfural.
ChemSusChem
PUBLISHED: 01-23-2014
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Efficient transformation of biomass-derived feedstocks to chemicals and fuels remains a daunting challenge in utilizing biomass as alternatives to fossil resources. A three-phase catalytic system, consisting of an aqueous phase, a hydrophobic ionic-liquid phase, and a solid-acid catalyst phase of nanostructured vanadium phosphate and mesostructured cellular foam (VPO-MCF), is developed for efficient conversion of biomass-derived fructose to 5-hydroxymethylfurfural (HMF). HMF is a promising, versatile building block for production of value-added chemicals and transportation fuels. The essence of this three-phase system lies in enabling the isolation of the solid-acid catalyst from the aqueous phase and regulation of its local environment by using a hydrophobic ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][Tf2N]). This system significantly inhibits the side reactions of HMF with H2O and leads to 91?mol?% selectivity to HMF at 89?% of fructose conversion. The unique three-phase catalytic system opens up an alternative avenue for making solid-acid catalyst systems with controlled and locally regulated microenvironment near catalytically active sites by using a hydrophobic ionic liquid.
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Determinants for the improved thermostability of a mesophilic family 11 xylanase predicted by computational methods.
Biotechnol Biofuels
PUBLISHED: 01-06-2014
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Xylanases have drawn much attention owing to possessing great potential in various industrial applications. However, the applicability of xylanases, exemplified by the production of bioethanol and xylooligosaccharides (XOSs), was bottlenecked by their low stabilities at higher temperatures. The main purpose of this work was to improve the thermostability of AuXyn11A, a mesophilic glycoside hydrolase (GH) family 11 xylanase from Aspergillus usamii E001, by N-terminus replacement.
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A T7 exonuclease-assisted cyclic enzymatic amplification method coupled with rolling circle amplification: a dual-amplification strategy for sensitive and selective microRNA detection.
Chem. Commun. (Camb.)
PUBLISHED: 01-03-2014
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A T7 exonuclease-assisted cyclic enzymatic amplification method (CEAM) was combined with rolling circle amplification (RCA) to develop a RCA-CEAM dual amplification method for ultrasensitive detection of microRNA with excellent selectivity.
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Impacts of Diffuse Radiation on Light Use Efficiency across Terrestrial Ecosystems Based on Eddy Covariance Observation in China.
PLoS ONE
PUBLISHED: 01-01-2014
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Ecosystem light use efficiency (LUE) is a key factor of production models for gross primary production (GPP) predictions. Previous studies revealed that ecosystem LUE could be significantly enhanced by an increase on diffuse radiation. Under large spatial heterogeneity and increasing annual diffuse radiation in China, eddy covariance flux data at 6 sites across different ecosystems from 2003 to 2007 were used to investigate the impacts of diffuse radiation indicated by the cloudiness index (CI) on ecosystem LUE in grassland and forest ecosystems. Our results showed that the ecosystem LUE at the six sites was significantly correlated with the cloudiness variation (0.24?R2?0.85), especially at the Changbaishan temperate forest ecosystem (R2?=?0.85). Meanwhile, the CI values appeared more frequently between 0.8 and 1.0 in two subtropical forest ecosystems (Qianyanzhou and Dinghushan) and were much larger than those in temperate ecosystems. Besides, cloudiness thresholds which were favorable for enhancing ecosystem carbon sequestration existed at the three forest sites, respectively. Our research confirmed that the ecosystem LUE at the six sites in China was positively responsive to the diffuse radiation, and the cloudiness index could be used as an environmental regulator for LUE modeling in regional GPP prediction.
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Molecular and Genetic Determinants of the NMDA Receptor for Superior Learning and Memory Functions.
PLoS ONE
PUBLISHED: 01-01-2014
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The opening-duration of the NMDA receptors implements Hebb's synaptic coincidence-detection and is long thought to be the rate-limiting factor underlying superior memory. Here, we investigate the molecular and genetic determinants of the NMDA receptors by testing the "synaptic coincidence-detection time-duration" hypothesis vs. "GluN2B intracellular signaling domain" hypothesis. Accordingly, we generated a series of GluN2A, GluN2B, and GluN2D chimeric subunit transgenic mice in which C-terminal intracellular domains were systematically swapped and overexpressed in the forebrain excitatory neurons. The data presented in the present study supports the second hypothesis, the "GluN2B intracellular signaling domain" hypothesis. Surprisingly, we found that the voltage-gated channel opening-durations through either GluN2A or GluN2B are sufficient and their temporal differences are marginal. In contrast, the C-terminal intracellular domain of the GluN2B subunit is necessary and sufficient for superior performances in long-term novel object recognition and cued fear memories and superior flexibility in fear extinction. Intriguingly, memory enhancement correlates with enhanced long-term potentiation in the 10-100 Hz range while requiring intact long-term depression capacity at the 1-5 Hz range.
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Aberrantly up-regulated miR-20a in pre-eclampsic placenta compromised the proliferative and invasive behaviors of trophoblast cells by targeting forkhead box protein A1.
Int. J. Biol. Sci.
PUBLISHED: 01-01-2014
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Preeclampsia is a serious complication in pregnancy. Dysregulation of trophoblast cell proliferation and invasion is a major pathological alteration observed in preeclampsia. Recently, microRNAs were shown to participate in the pathogenesis of preeclampsia. In this study we explored the effect of miR-20a on the proliferation and invasion of trophoblast cells and the underlying mechanism. We verified the distribution of miR-20a in human placenta by in situ hybridization. Real time PCR data showed that the level of miR-20a increased by 2.6 folds in human preeclampsia than normal tissues. We then cultured trophoblast-like JEG-3 cells and evaluated the effect of miR-20a on JEG-3 cell proliferation, migration and invasion. Overexpression of miR-20a significantly inhibited the proliferation, migration and invasion of cultured JEG-3 cells, which were abolished by co-transfection of AMO-20a. Transfection of miR-20a also inhibited JEG-3 cell xenograft tumor growth in nude mice. Luciferase assay technique was used to identify the direct regulation of miR-20a on Forkhead Box Protein A1(FOXA1). Transfection of miR-20a markedly reduced the luciferase activity of the chimeric plasmid containing the 3'UTR of FOXA1, indicating FOXA1 is the target of miR-20a. Furthermore, transfection of miR-20a inhibited both protein and mRNA expression of FOXA1 in JEG-3 cells. In summary, the upregulated miR-20a in human preeclampsia tissue can inhibit the proliferative and invasive activities of trophoblast cells by repressing the expression of FOXA1.
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A highly parallel microfluidic droplet method enabling single-molecule counting for digital enzyme detection.
Biomicrofluidics
PUBLISHED: 01-01-2014
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Although digital detection of nucleic acids has been achieved by amplification of single templates in uniform microfluidic droplets and widely used for genetic analysis, droplet-based digital detection of proteins has rarely been reported, largely due to the lack of an efficient target amplification method for protein in droplets. Here, we report a key step towards digital detection of proteins using a highly parallel microfluidic droplet approach for single enzyme molecule detection in picoliter droplets via enzyme catalyzed signal amplification. An integrated microfluidic chip was designed for high throughput uniform droplet generation, monolayer droplet collection, incubation, detection, and release. Single ?-galatosidase (?-Gal) molecules and the fluorogenic substrate fluorescein di-?-D-galactopyranoside were injected from two separated inlets to form uniform 20??m droplets in fluorinated oil at a frequency of 6.6?kHz. About 200?000 droplets were captured as a monolayer in a capture well on-chip for subsequent imaging detection. A series of ?-Gal solutions at different concentrations were analyzed at the single-molecule level. With no enzyme present, no droplets were found to fluoresce, while brightly fluorescent droplets were observed under single-enzyme molecule conditions. Droplet fluorescence intensity distribution analysis showed that the distribution of enzyme molecules under single-molecule conditions matched well with theoretical prediction, further proving the feasibility of detecting single enzyme molecules in emulsion droplets. Moreover, the population of fluorescent droplets increased as the ?-Gal concentration increased. Based on a digital counting method, the measured concentrations of the enzyme were found to match well with input enzyme concentration, establishing the accuracy of the digital detection method for the quantification of ?-Gal enzyme molecules. The capability of highly parallel detection of single enzyme molecules in uniform picoliter droplets paves the way to microdroplet based digital detection of proteins.
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Radiation Stability of Cations in Ionic Liquids. 3. Guanidinium Cations.
J Phys Chem B
PUBLISHED: 11-08-2013
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Due to their superb structural versatility, guanidinium cations find increasing use as constituent ions in room temperature ionic liquids (ILs). This versatility allows fine-tuning of hydrophobicity, which is an important concern for the use of ILs as diluents for metal ion separations. However, the presence of six C-N bonds in such cations poses a question, whether the guanidinium based ILs can be considered as diluents for nuclear separations, given that the radiation emitted by the decaying radionuclides can break these relatively weak bonds over the use cycle of the solvent. As nothing is presently known about the radiolytic stability of the guanidinium cations, we addressed this question using 2-dialkylamino-1,3-dimethylimidazolidine based cations (R = Et, Pr, and Bu) as a representative model for the entire class of such cations, and assessed their stability in 2.5 MeV electron beam radiolysis. Electron paramagnetic resonance spectroscopy, nuclear magnetic resonance spectroscopy, and mass spectrometry have been used to establish chemical mechanisms for radiation damage in guanidinium cations. Our conclusion is that radiation stability of these cations is not significantly different from that of more familiar aliphatic and aromatic IL cations. In fact, these cations yield exceptionally stable radicals, and fragmentation occurs only in their radiolytically generated excited states. The predominant chemical pathway for the cation decomposition is the elimination of their aliphatic arms, with radiolytic yields of 0.65 to 1.06 to 1.46 per 100 eV from R = Et to R = Bu, respectively. The total loss of the parent cation was estimated as 2.62, 1.65, and 1.98 species per 100 eV. While this attrition is not negligible, it is comparable to other organic cations that have fewer fissile C-N bonds. Many of the products are either modified guanidinium ions or protonated bases that are not expected to interfere with radionuclide separations.
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Radiation Stability of Cations in Ionic Liquids. 1. Alkyl and Benzyl Derivatives of 5-Membered Ring Heterocycles.
J Phys Chem B
PUBLISHED: 11-08-2013
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In order to use hydrophobic room temperature ionic liquids (ILs) as diluents in nuclear separations for advanced fuel cycles, it is desirable to reduce the breakdown of the constituent ions caused by ionizing radiation. In this series, we survey radiation stability for different classes of organic cations used to formulate ILs. While radiolysis of 1-alkyl-3-methylimidazolium cations has been extensively studied, there have not been complementary studies of 1-benzyl derivatives of these cations nor organic cations that are derived from 5-membered ring heterocycles other than imidazole, such as 1,2,4-triazole and thiazole. In part 1, we establish the fragmentation pathways for such cations and quantify product yields for 2.5 MeV electron beam radiolysis of these aromatic cations. Radiolytic reduction of 1-benzyl cations derived from imidazole and 1,2,4-triazole is shown to cause the elimination of benzyl radicals from their electron adducts, whereas this elimination does not occur in the thiazole derivatives due to stabilization of the excess electron as a dimer radical cation. No such elimination occurs in the corresponding 1-alkyl derivatives, but there is significant C-N and C-C bond fragmentation in the aliphatic arms. As such bond dissociation reactions are irreversible, there is significant loss of 1-alkyl cations during the radiolysis. For 1-benzyl derivatives, this electronic excitation causes fragmentation of the C-N bonds in the benzyl arms with the release of the corresponding base and the benzyl carbocation that can subsequently attack this base or add to another cation. Such systems exhibit more predictable fragmentation patterns and yield well-defined products; some of the systems also exhibit increased radiation resistance. The C-N bond fragmentation in the reduced cations can be further suppressed through the use of appropriate electron scavengers, including acids and aromatic imide anions. The observed trends are rationalized using density functional theory calculations, and the implications of these results for the design of IL diluents are examined.
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Kurthia huakuii sp. nov., a new member of the genus Kurthia isolated from biogas slurry in China,and emended description of the genus Kurthia.
Int. J. Syst. Evol. Microbiol.
PUBLISHED: 10-09-2013
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A novel facultative aerobic bacterium, designated strains LAM0618(T), was isolated from biogas slurry samples collected from the large-scale anaerobic digester of Modern Farming Corporation in Hebei Province, China. Cells of strain LAM0618(T) were Gram-positive, motile, non-spore forming and short-rod shaped with a cell size of 0.5 ?m to 0.8 ?m × 2.0 ?m to 4.0 ?m. The temperature and pH ranges for growth were 10 °C to 45 °C (optimum: 30 °C) and 5.5 to 9.5 (optimum: 7.0), respectively. The strain did not require NaCl for growth but tolerated up to 70 g NaCl L(-1). Compared with the reference strains, cells of strain LAM0618(T) had positive utilization of D-maltose, D-fructose, Tween 40, citrate and lactate. The major fatty acids of strain LAM0618(T) were iso-C15:0(47.2%), anteiso-C15:0(8.2%), iso-C14:0(6.5%), C16:0(6.3%), and C18:0(5.6%). The predominant menaquinones of strain LAM0618(T) were menaquinone 7 (MK-7) and menaquinone 6 (MK-6). The genomic DNA G+C content was 41 mol% as determined by Tm method. Analysis of the 16S rRNA gene sequence revealed that strain LAM0618(T) was a member of the genus Kurthia, and was most closely related to K. massiliensis DSM 24639(T), K. zopfii DSM 20580(T), K. gibsonii DSM 20636(T), and K. sibirica DSM 4747(T), with 96.9%, 95.7%, 95.6% and 94.9% sequence similarity, respectively. Based on its phenotypic and genotypic properties, strain LAM0618(T) was suggested to represent a novel species of the genus Kurthia, for which the name Kurthia huakuii sp.nov. is proposed. The type strain is LAM0618(T) (=ACCC 06121(T) =JCM 19187(T)).
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A thermophilic ?-galactosidase from Neosartorya fischeri P1 with high specific activity, broad substrate specificity and significant hydrolysis ability of soymilk.
Bioresour. Technol.
PUBLISHED: 10-05-2013
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An extracellular ?-galactosidase (Gal27A) with high specific activity of 423Umg(-1) was identified in thermophilic Neosartorya fischeri P1. Its coding gene (1680bp) was cloned and functionally expressed in Pichia pastoris. Sequence analysis indicated that deduced Gal27A contains a catalytic domain of glycoside hydrolase family 27. The native and recombinant enzymes shared some similar properties, such as pH optima at 4.5, temperature optima at 60-70°C, resistance to most chemicals and saccharides, and great abilities to degrade raffinose and stachyose in soymilk. Considering the high yield (3.1gL(-1)) in P. pastoris, recombinant rGal27A is more favorable for industrial applications. This is the first report on purification and gene cloning of Neosartorya ?-galactosidase.
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[Metronomic chemotherapy combined with dendritic cell vaccine ?inhibits VEGF secretion].
Zhongguo Fei Ai Za Zhi
PUBLISHED: 09-17-2013
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The survival rate of lung cancer is low, thus new methods for treating this form of cancer must be explored. This study applies immune therapy with metronomic chemotherapy to observe the effect of combined therapy on suppressing tumor.
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Elevated COX2 expression and PGE2 production by downregulation of RXR? in senescent macrophages.
Biochem. Biophys. Res. Commun.
PUBLISHED: 09-06-2013
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Increased systemic level of inflammatory cytokines leads to numerous age-related diseases. In senescent macrophages, elevated prostaglandin E2 (PGE2) production contributes to the suppression of T cell function with aging, which increases the susceptibility to infections. However, the regulation of these inflammatory cytokines and PGE2 with aging still remains unclear. We have verified that cyclooxygenase (COX)-2 expression and PGE2 production are higher in LPS-stimulated macrophages from old mice than that from young mice. Downregulation of RXR?, a nuclear receptor that can suppress NF-?B activity, mediates the elevation of COX2 expression and PGE2 production in senescent macrophages. We also have found less induction of ABCA1 and ABCG1 by RXR? agonist in senescent macrophages, which partially accounts for high risk of atherosclerosis in aged population. Systemic treatment with RXR? antagonist HX531 in young mice increases COX2, TNF-?, and IL-6 expression in splenocytes. Our study not only has outlined a mechanism of elevated NF-?B activity and PGE2 production in senescent macrophages, but also provides RXR? as a potential therapeutic target for treating the age-related diseases.
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Robust Mixed l1/H? Filtering for Affine Fuzzy Systems With Measurement Errors.
IEEE Trans Cybern
PUBLISHED: 09-05-2013
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This paper investigates the robust filtering problem for a class of nonlinear systems described by affine fuzzy parts with norm-bounded uncertainties. The system outputs are chosen as the premise variables of fuzzy models, and their measured values are chosen as the premise variables and inputs of fuzzy filters. The measurement errors between the outputs of the plant and the inputs of the filter are considered, and as a result, the plant and the estimator cannot always evolve in the same region at the same time, especially in the neighborhoods of region boundaries. By using a piecewise Lyapunov function combined with S-procedure and adding slack matrix variables, a fuzzy-basis-dependent mixed l1/H? filter design method is obtained in the formulation of linear matrix inequalities, which allows for reducing the worst case peak output due to the measurement errors, and satisfying an H?-norm constraint. In contrast to existing work, the proposed fuzzy-basis-dependent filter can guarantee a better H? performance and less computational burden. Finally, a numerical example illustrates the effectiveness of the proposed method.
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A novel local anti-colorectal cancer drug delivery system: negative lipidoid nanoparticles with a passive target via a size-dependent pattern.
Nanotechnology
PUBLISHED: 08-21-2013
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The nontoxic, targeted and effective delivery of nucleic acid drugs remains an important challenge for clinical development. Here, we describe a novel negative lipidoid nanoparticle delivery system, providing entrapment-based transfection agents for local delivery of siRNA to the colorectal cancer focus. The delivery system was synthesized with lipidoid material 98N12-5(1), mPEG2000-C12/C14 glyceride and cholesterol at a desired molar ratio to realize the anionic surface charge of particles, which could alleviate to a larger degree the inflammatory response and immune stimulation of the organism, embodying dramatic biocompatibility. In particular, mPEG2000-C12/C14 glyceride was selected to ameliorate the stability of the delivery system and protection of nucleic acids by extending the tail length of the carbons, crucial also to neutralize the positive charge of 98N12-5(1) to form a resultant anionic particle. In vivo experiments revealed that a particle size of 90 nm perfectly realized a passive target in a size-dependent manner and did not affect the function of the liver and kidneys by a local delivery method, enema. We clarified that the uptake of negative lipidoid nanoparticles internalized through a lipid raft endocytotic pathway with low cytotoxicity, strong biocompatibility and high efficacy. This study suggests that negative lipidoid nanoparticles with enema delivery constitute, uniquely and appropriately, a local anti-colorectal cancer nucleic acid drug delivery platform, and the application of similar modes may be feasible in other therapeutic settings.
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Single-molecule photon-fueled DNA nanoscissors for DNA cleavage based on the regulation of substrate binding affinity by azobenzene.
Chem. Commun. (Camb.)
PUBLISHED: 08-21-2013
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A pair of single-molecule photo-responsive DNA nanoscissors for DNA cleavage based on the regulation of substrate binding affinity was designed and fabricated. Compared with other DNA nanomachines, our DNA nanoscissors have the advantages of a clean switching mechanism, as well as robust and highly reversible operation.
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Bilateral stereotactic radiofrequency amygdalohippocampectomy for a patient with bilateral temporal lobe epilepsy.
Epilepsia
PUBLISHED: 08-20-2013
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To search for a method for treatment of bilateral temporal lobe epilepsy (BTLE), we report one patient with BTLE experienced bilateral stereotactic radiofrequency amygdalohippocampectomy (SAHE). Neuropsychological examinations were performed before and 5 days, and 6, 18, and 48 months after operation. No seizure occurred in the follow-up time, and no long-term memory and intelligence deficits were found except for a transient decline of the scores immediately after operation. Because severe damage of memory could be caused by bilateral resection surgery, bilateral SAHE should be considered as a possible approach for the treatment of BTLE. However, further studies with accumulation of cases are needed, especially in the detailed assessment of neuropsychological function.
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[Correlation between thermostability of the xylanase EvXyn11(TS) and its N-terminal disulfide bridge].
Wei Sheng Wu Xue Bao
PUBLISHED: 07-18-2013
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To reveal the correlation between thermostability of xylanase EvXyn11(TS) and its N-terminal disulfide bridge, an EvXyn11(TS)-encoding gene (Syxyn11) was synthesized and subjected to site-directed mutagenesis.
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Novel 3D SEM Moiré method for micro height measurement.
Opt Express
PUBLISHED: 07-12-2013
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A 3D SEM Moiré Method (SMM) is proposed in this investigation for the first time for 3D shape measurement with nano-scale sensitivity. The geometric model of the 3D SMM has been theoretically established, combining the stereovision technology in an SEM with the existing principles of in-plane SMM. The Virtual Projection Fringe (VPF) generated under different conditions has been analyzed for 3D reconstructions. Two typical applications have been used to experimentally validate the theoretical model. Experimental results, with the height measurement sensitivity less than 10nm, agree well with the theoretical model we proposed. The uncertainty analysis for the method has also been performed by other auxiliary measurements.
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Graphene oxide protected nucleic acid probes for bioanalysis and biomedicine.
Chemistry
PUBLISHED: 07-09-2013
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Recently, the binding ability of DNA on GO and resulting nuclease resistance have attracted increasing attention, leading to new applications both in vivo and in vitro. In vivo, nucleic acids absorbed on GO can be effectively protected from enzymatic degradation and biological interference in complicated samples, making it useful for targeted delivery, gene regulation, intracellular detection and imaging with high uptake efficiencies, high intracellular stability, and very low toxicity. In vitro, the adsorption of ssDNA on GO surface and desorption of dsDNA or well-folded ssDNA from GO surface result in the protection and deprotection of DNA from nucleic digestion, respectively, which has led to target-triggered cyclic enzymatic amplification methods (CEAM) for amplified detection of analytes with sensitivity 2-3 orders of magnitude higher than that of 1:1 binding strategies. This Concept article explores some of the latest developments in this field.
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IGF-1R and Bmi-1 expressions in lung adenocarcinoma and their clinicopathologic and prognostic significance.
Tumour Biol.
PUBLISHED: 06-24-2013
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IGF-1R and Bmi-1 play a critical role in cancer growth and survival. We explored the correlation between IGF-1R and Bmi-1, as well as their relationship with clinicopathological parameters and their impacts on outcomes in patients with lung adenocarcinoma resected. Tumors from 178 surgical lung adenocarcinoma patients were evaluated for IGF-1R and Bmi-1 expression by means of immunohistochemistry. The clinicopathological implications of these molecules were analyzed statistically. There was a significant correlation between the expression of IGF-1R and Bmi-1 (p?=?0.011). The 5-year survival rate of patients with Bmi-1 positive was only 31.2 %, but patients with Bmi-1 negative had a survival rate of 50.7 % (p?=?0.004). The pattern of survival curves showed that Bmi-1 was a significant prognostic factor of poor overall survival in lung adenocarcinoma patients. However, there was no obvious correlation between IGF-1R expression and patient survival. The results of multivariate Cox analysis revealed that the pathological stages and Bmi-1 expression were independent prognostic factors. Therefore, Bmi-1 may be a good biomarker to predict the prognosis of patients with completely resected lung adenocarcinoma.
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Tumor-suppressive effects of miR-29c on gliomas.
Neuroreport
PUBLISHED: 06-08-2013
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Although miR-29c has been shown to be expressed less in various kinds of solid cancers, its expression pattern and tumor-suppressive effects in gliomas remain largely unknown. In this study, we detected miR-29c in 10 nontumoral brain tissues and 60 gliomas of various grades and found that its labeling indexes were significantly lower in gliomas (53.7% for the nontumoral brain tissues, and 18.9, 5.5, and 1.8% for the WHO grade I-II, grade III, and grade IV glioma groups, respectively). We then overexpressed miR-29c in the SNB19 glioblastoma cell line and found that it markedly downregulated the expression level of CDK6, and accordingly increased the percentage of the tumor cells in the G1 phase from 44.5 to 69.1% and decreased the colony formation efficiency from 81.1 to 51.5%. miR-29c overexpression also increased the percentage of apoptotic cells from 27.2 to 54.8%, and led to a more than 50% decrease in the migratory and invasive abilities of the tumor cells. Our study shows that miR-29c can effectively block the proliferation of glioblastoma cells by inducing G1 arrest, promote their apoptosis, and inhibit their migration and invasion. At least some of its tumor-suppressive effects are mediated by specifically downregulating the expression of CDK6. Therefore, miR-29c can be used as a tumor suppressor in the gene therapy of malignant gliomas.
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Brucella BioR regulator defines a complex regulatory mechanism for bacterial biotin metabolism.
J. Bacteriol.
PUBLISHED: 05-31-2013
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The enzyme cofactor biotin (vitamin H or B7) is an energetically expensive molecule whose de novo biosynthesis requires 20 ATP equivalents. It seems quite likely that diverse mechanisms have evolved to tightly regulate its biosynthesis. Unlike the model regulator BirA, a bifunctional biotin protein ligase with the capability of repressing the biotin biosynthetic pathway, BioR has been recently reported by us as an alternative machinery and a new type of GntR family transcriptional factor that can repress the expression of the bioBFDAZ operon in the plant pathogen Agrobacterium tumefaciens. However, quite unusually, a closely related human pathogen, Brucella melitensis, has four putative BioR-binding sites (both bioR and bioY possess one site in the promoter region, whereas the bioBFDAZ [bio] operon contains two tandem BioR boxes). This raised the question of whether BioR mediates the complex regulatory network of biotin metabolism. Here, we report that this is the case. The B. melitensis BioR ortholog was overexpressed and purified to homogeneity, and its solution structure was found to be dimeric. Functional complementation in a bioR isogenic mutant of A. tumefaciens elucidated that Brucella BioR is a functional repressor. Electrophoretic mobility shift assays demonstrated that the four predicted BioR sites of Brucella plus the BioR site of A. tumefaciens can all interact with the Brucella BioR protein. In a reporter strain that we developed on the basis of a double mutant of A. tumefaciens (the ?bioR ?bioBFDA mutant), the ?-galactosidase (?-Gal) activity of three plasmid-borne transcriptional fusions (bioBbme-lacZ, bioYbme-lacZ, and bioRbme-lacZ) was dramatically decreased upon overexpression of Brucella bioR. Real-time quantitative PCR analyses showed that the expression of bioBFDA and bioY is significantly elevated upon removal of bioR from B. melitensis. Together, we conclude that Brucella BioR is not only a negative autoregulator but also a repressor of expression of bioY and bio operons that separately function in biotin transport and the biosynthesis pathway.
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Engineering the thermostability of a xylanase from Aspergillus oryzae by an enhancement of the interactions between the N-terminus extension and the ?-sheet A2 of the enzyme.
Biotechnol. Lett.
PUBLISHED: 05-15-2013
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A mesophilic Aspergillus oryzae xylanase (AoXyn11A) belongs to glycoside hydrolase family 11. Hydrogen bonds and a disulfide bridge were introduced between the N-terminus extension and the ?-sheet A2 of AoXyn11A, which were located in the corresponding region of a hyperthermostable xylanase. The mutants were designated as AoXyn11A(C5) and AoXyn11A(C5-C32), respectively. The thermostabilities of AoXyn11A and the mutants were assessed by the molecular dynamics simulations. After being incubated at 55 °C for 30 min, AoXyn11A(C5-C32) retained 49 % of its original activity, AoXyn11A(C5) retained 12 % and AoXyn11A retained 3 %. The interactions between the N-terminus extension and the ?-sheet A2 were analyzed in depth: there was enhancement of the interactions between the N-terminus extension and the ?-sheet A2 of AoXyn11A that improved its thermostability.
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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.