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Find video protocols related to scientific articles indexed in Pubmed.
Metal Seed Layer Thickness-Induced Transition From Vertical to Horizontal Growth of MoS2 and WS2.
Nano Lett.
PUBLISHED: 11-19-2014
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Two-dimensional (2D), layered transition metal dichalcogenides (TMDCs) can grow in two different growth directions, i.e., horizontal and vertical. In the horizontal growth, 2D TMDC layers grow in planar direction with their basal planes parallel to growth substrates. In the vertical growth, 2D TMDC layers grow standing upright on growth substrates exposing their edge sites rather than their basal planes. The two distinct morphologies present unique materials properties suitable for specific applications, such as horizontal TMDCs for opto-electronics and vertical TMDCs for electrochemical reactions. Precise control of the growth orientation is essential for realizing the true potential of these 2D materials for large-scale, practical applications. In this Letter, we investigate the transition of vertical-to-horizontal growth directions in 2D molybdenum (or, tungsten) disulfides and study the underlying growth mechanisms and parameters that dictate such transition. We reveal that the thickness of metal seed layers plays a critical role in determining their growth directions. With thick (> ~ 3 nm) seed layers, the vertical growth is dominant, while the horizontal growth occurs with thinner seed layers. This finding enables the synthesis of novel 2D TMDC heterostructures with anisotropic layer orientations and transport properties. The present study paves a way for developing a new class of 2D TMDCs with unconventional materials properties.
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FeP Nanoparticles Film Grown on Carbon Cloth: An Ultrahighly Active 3D Hydrogen Evolution Cathode in Both Acidic and Neutral Solutions.
ACS Appl Mater Interfaces
PUBLISHED: 11-18-2014
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In this Letter, we demonstrate the direct growth of FeP nanoparticles film on carbon cloth (FeP/CC) through low-temperature phosphidation of its Fe3O4/CC precursor. Remarkably, when used as an integrated 3D hydrogen evolution cathode, this FeP/CC electrode exhibits ultrahigh catalytic activity comparable to commercial Pt/C and good stability in acidic media. This electrode also performs well in neutral solutions. This work offers us the most cost-effective and active 3D cathode toward electrochemical water splitting for large-scale hydrogen fuel production.
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Electrochemically Created Highly Surface Roughened Ag Nanoplate Arrays for SERS Biosensing Applications.
J Mater Chem C Mater Opt Electron Devices
PUBLISHED: 11-11-2014
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Highly surface-roughened Ag nanoplate arrays are fabricated using a simple electrodeposition and in situ electrocorrosion method with inorganic borate ions as capping agent. The electrocorrosion process is induced by a change in the local pH value during the electrochemical growth, which is used to intentionally carve the electrodeposited structures. The three dimensionally arranged Ag nanoplates are integrated with substantial surface-enhanced Raman scattering (SERS) hot spots and are free of organic contaminations widely used as shaping agents in previous works, making them excellent candidate substrates for SERS biosensing applications. The SERS enhancement factor of the rough Ag nanoplates is estimated to be > 10(9). These Ag nanoplate arrays are used for SERS-based analysis of DNA hybridization monitoring, protein detection, and virus differentiation without any additional surface modifications or labelling. They all exhibit an extremely high detection sensitivity, reliability, and reproducibility.
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[The clinical and imaging study of thalamic venous infarction].
Zhonghua Nei Ke Za Zhi
PUBLISHED: 11-08-2014
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To explore the clinical and radiological features of bilateral thalamus venous infarction.
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[Molecular typing and surveillance on Salmonella typhimurium strain in Guangdong province, 2009-2011].
Zhonghua Liu Xing Bing Xue Za Zhi
PUBLISHED: 11-08-2014
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To understand the distribution and the characteristics on molecular typing of Salmonella (S.) typhimurium isolates gathered from the surveillance program and to construct the standard S. typhimurium databank in the laboratory through surveillance network PulseNet, in Guangdong province to improve the capability of detection on laboratory-based foodborne outbreaks.
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Human Influenza A(H7N9) Virus Infection Associated with Poultry Farm, Northeastern China.
Emerging Infect. Dis.
PUBLISHED: 10-24-2014
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We report on a case of human infection with influenza A(H7N9) virus in Jilin Province in northeastern China. This case was associated with a poultry farm rather than a live bird market, which may point to a new focus for public health surveillance and interventions in this evolving outbreak.
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Incident-angle dependent color tuning from a single plasmonic chip.
Nanotechnology
PUBLISHED: 10-22-2014
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We report on a broad color tuning effect covering the visible range from a single plasmonic chip. By simply tilting the orientation of the designed plasmonic chip within a certain range, the photon-plasmon coupling interactions between the incident light and the plasmonic nanostructures on the chip can be finely tuned, resulting in an angle-dependent continuous color filtering effect. The physical mechanism of the device is investigated through the full-wave calculations, which provide important guidance for the design and optimization of the proposed devices. The broad color tuning from the demonstrated single chip will potentially benefit visualization and display technologies, and is particularly useful for the construction of reflection-based spatial light modulators.
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[Application of noninvasive fetal trisomy testing based on massively parallel sequencing for the detection of chromosomal deletions and duplications].
Zhonghua Yi Xue Yi Chuan Xue Za Zhi
PUBLISHED: 10-10-2014
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To assess the value of noninvasive fetal trisomy testing based on massively parallel sequencing for the detection of chromosomal deletions and duplications.
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Er:YAG laser versus scaling and root planing as alternative or adjuvant for chronic periodontitis treatment: a systematic review.
J. Clin. Periodontol.
PUBLISHED: 10-10-2014
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To perform a systematic review to evaluate the erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser versus scaling and root planing (SRP) as alternative or adjuvant for chronic periodontitis treatment.
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Connection between the packing efficiency of binary hard spheres and the glass-forming ability of bulk metallic glasses.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 09-29-2014
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We perform molecular dynamics simulations to compress binary hard spheres into jammed packings as a function of the compression rate R, size ratio ?, and number fraction x_{S} of small particles to determine the connection between the glass-forming ability (GFA) and packing efficiency in bulk metallic glasses (BMGs). We define the GFA by measuring the critical compression rate R_{c}, below which jammed hard-sphere packings begin to form "random crystal" structures with defects. We find that for systems with ??0.8 that do not demix, R_{c} decreases strongly with ??_{J}, as R_{c}?exp(-1/??_{J}^{2}), where ??_{J} is the difference between the average packing fraction of the amorphous packings and random crystal structures at R_{c}. Systems with ??0.8 partially demix, which promotes crystallization, but we still find a strong correlation between R_{c} and ??_{J}. We show that known metal-metal BMGs occur in the regions of the ? and x_{S} parameter space with the lowest values of R_{c} for binary hard spheres. Our results emphasize that maximizing GFA in binary systems involves two competing effects: minimizing ? to increase packing efficiency, while maximizing ? to prevent demixing.
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[Evaluation of left ventricular myocardial function in coronary atherosclerosis patients with type 2 diabetes mellitus by speckle tracking echocardiography].
Zhonghua Yi Xue Za Zhi
PUBLISHED: 09-26-2014
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To evaluate the left ventricular (LV) myocardial function in coronary atherosclerosis patients with type 2 diabetes mellitus (DM) by two-dimensional speckle tracking echocardiography (2D STE).
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Label-Free Measurements of Reaction Kinetics Using a Droplet-Based Optofluidic Device.
J Lab Autom
PUBLISHED: 09-25-2014
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Label-free measurements of the reaction kinetics of a small sample volume are essential for efficient drug discovery, requiring methods and systems that are rapid, accurate, and cost-effective. Herein, we present an integrated optofluidic system for label-free characterization of reactions in a nanoliter reagent volume. This system contains a droplet-based microfluidic sampling section and an optical fiber-based spectroscopy detection section. By manipulating droplets containing reagents at certain concentrations at different times, quantifiable measurements via absorption spectroscopy can be made in a simple, sensitive, and high-throughput manner. We have demonstrated our system's capability by performing potency (IC50) assays of an inhibitor in a TEM-1 ?-lactamase (enzyme) and nitrocefin (substrate) system. This integrated platform can potentially provide an automated, label-free, and low-cost method for many other assays of reaction kinetics.
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Exome sequencing identifies mutations in ABCD1 and DACH2 in two brothers with a distinct phenotype.
BMC Med. Genet.
PUBLISHED: 09-19-2014
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BackgroundWe report on two brothers with a distinct syndromic phenotype and explore the potential pathogenic cause.MethodsCytogenetic tests and exome sequencing were performed on the two brothers and their parents. Variants detected by exome sequencing were validated by Sanger sequencing.ResultsThe main phenotype of the two brothers included congenital language disorder, growth retardation, intellectual disability, difficulty in standing and walking, and urinary and fecal incontinence. To the best of our knowledge, no similar phenotype has been reported previously. No abnormalities were detected by G-banding chromosome analysis or array comparative genomic hybridization. However, exome sequencing revealed novel mutations in the ATP-binding cassette, sub-family D member 1 (ABCD1) and Dachshund homolog 2 (DACH2) genes in both brothers. The ABCD1 mutation was a missense mutation c.1126G¿>¿C in exon 3 leading to a p.E376Q substitution. The DACH2 mutation was also a missense mutation c.1069A¿>¿T in exon 6, leading to a p.S357C substitution. The mother was an asymptomatic heterozygous carrier. Plasma levels of very-long-chain fatty acids were increased in both brothers, suggesting a diagnosis of adrenoleukodystrophy (ALD); however, their phenotype was not compatible with any reported forms of ALD. DACH2 plays an important role in the regulation of brain and limb development, suggesting that this mutation may be involved in the phenotype of the two brothers. ConclusionThe distinct phenotype demonstrated by these two brothers might represent a new form of ALD or a new syndrome. The combination of mutations in ABCD1 and DACH2 provides a plausible mechanism for this phenotype.
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TSC1-mTORC1 signaling determines brown-to-white adipocyte phenotypic switch.
Diabetes
PUBLISHED: 09-13-2014
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Interconversion of white and brown adipocytes occurs between anabolic and catabolic states. The molecular mechanism regulating this phenotypic switch remains largely unknown. This study explores the role of tuberous sclerosis complex 1 (TSC1)-mechanistic target of rapamycin (mTOR) signaling in the conversion of brown to white adipose tissue. A colony of Fabp4-Tsc1-/- mice, in which the Tsc1 gene was specifically deleted by the fatty acid binding protein 4 (FABP4)-Cre, was established. Western blotting and immunostaining demonstrated the absence of TSC1 and activation of ribosomal protein S6 kinase 1, the downstream target of mTOR complex 1 (mTORC1) signaling, in the brown adipose tissues (BAT) of Fabp4-Tsc1-/- mice. Accumulation of lipid droplets in BAT was significantly increased. Levels of brown adipocyte markers were markedly down-regulated, while white adipocyte markers up-regulated. Rapamycin reversed the conversion from BAT to WAT in Fabp4-Tsc1-/- mice. Deletion of Tsc1 gene in cultured brown preadipocytes significantly increased the conversion to white adipocytes. FoxC2 mRNA, the transcriptional factor for brown adipocyte determination, was significantly decreased, while mRNAs for Rb, p107 and RIP140, the transcriptional factors for white adipocyte determination, increased in the BAT of Fabp4-Tsc1-/- mice. Our study demonstrates that TSC1-mTORC1 signaling contributes to the brown-to-white adipocyte phenotypic switch.
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[Dosage and curative effect of blood coagulation factor VIII in the prevention and treatment of haemophilia A in children].
Zhong Nan Da Xue Xue Bao Yi Xue Ban
PUBLISHED: 09-10-2014
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To study the correlation between dosage and curative effect of blood coagulation factor VIII in the prevention and treatment of haemophilia A in children and to determine the suitable dose for prevention of hemophilia in developing countries.
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Carbon nanotube-fullerene hybrid nanostructures by C?? bombardment: formation and mechanical behavior.
Phys Chem Chem Phys
PUBLISHED: 09-08-2014
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This study reports the investigation on C60 bombardment on the carbon nanotube (CNT) by molecular dynamic (MD) simulations. We found that carbon nanotube nanobuds or nanotube-fullerene hybrid nanostructures can be formed by C60 bombardment. Different from the nanobuds in earlier studies, more structural patterns are found in the bombardment formed nanobuds and nanotube-fullerene hybrid nanostructures. In addition, the attaching strengths of the carbon nanobuds are explored, and results indicate that the junction between C60 and CNTs in the nanobuds is very stable. Moreover, we also found that the bombardment formed nanobuds and nanotube-fullerene hybrid nanostructures generally decrease the maximum tensile strength and Young's modulus of carbon nanotubes.
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The molecular symplesiomorphies shared by the stem groups of metazoan evolution: can sites as few as 1% have a significant impact on recognizing the phylogenetic position of myzostomida?
J. Mol. Evol.
PUBLISHED: 08-17-2014
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Although it is clear that taxon sampling, alignments, gene sampling, tree reconstruction methods and the total length of the sequences used are critical to the reconstruction of evolutionary history, weakly supported or misleading nodes exist in phylogenetic studies with no obvious flaw in those aspects. The phylogenetic studies focusing on the basal part of bilaterian evolution are such a case. During the past decade, Myzostomida has appeared in the basal part of Bilateria in several phylogenetic studies of Metazoa. However, most researchers have entertained only two competing hypotheses about the position of Myzostomida-an affinity with Annelida and an affinity with Platyhelminthes. In this study, dozens of symplesiomorphies were discovered by means of ancestral state reconstruction in the complete 18S and 28S rDNAs shared by the stem groups of Metazoa. By contrastive analysis on the datasets with or without such symplesiomorphic sites, we discovered that Myzostomida and other basal groups are basal lineages of Bilateria due to the corresponding symplesiomorphies shared with earlier lineages. As such, symplesiomorphies account for approximately 1-2% of the whole dataset have an essential impact on phylogenetic inference, and this study reminds molecular systematists of the importance of carrying out ancestral state reconstruction at each site in sequence-based phylogenetic studies. In addition, reasons should be explored for the low support of the hypothesis that Myzostomida belongs to Annelida in the results of phylogenomic studies. Future phylogenetic studies concerning Myzostomida should include all of the basal lineages of Bilateria to avoid directly neglecting the stand-alone basal position of Myzostomida as a potential hypothesis.
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Ruthenium (II) Complexes Interact with Human Serum Albumin and Induce Apoptosis of Tumor Cells.
Biol Trace Elem Res
PUBLISHED: 08-15-2014
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The interaction of ruthenium (II) complex [Ru(bpy)2(mal)](2+) (RBM) and [Ru(phen)2(mal)](2+) (RPM) (bpy?=?2, 2-bipyridine, phen?=?1,10-phenanthroline, mal?=?malonyl carboxylate) with human serum albumin (HSA) has been investigated by using fluorescence, UV absorption and circular dichroism (CD) spectroscopy approaches. A strong fluorescence quenching reaction of complexes to HSA was observed and the quenching mechanism was suggested as static quenching according to the Stern-Volmer (S-V) equation. The number of binding sites n and observed binding constant Kb was measured by fluorescence quenching method. The thermodynamic parameters ?H, ?S, and ?G at different temperatures were calculated and the results indicate the binding reaction is mainly entropy-driven and Vander Waals force played a major role in the reaction. The result of CD showed that the secondary structure of HSA molecules was changed in the presence of the ruthenium (II) complexes. Furthermore, the cell viability of ruthenium (II) complexes was evaluated by MTT and complex RPM has shown significant higher anticancer potency than RBM against all the cell lines screened. RPM showed a significant antitumor activity through induction of apoptosis in A549 cells.
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One-pot transformation of cellobiose to formic acid and levulinic acid over ionic-liquid-based polyoxometalate hybrids.
ChemSusChem
PUBLISHED: 08-08-2014
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Currently, levulinic acid (LA) and formic acid (FA) are considered as important carbohydrates for the production of value-added chemicals. Their direct production from biomass will open up a new opportunity for the transformation of biomass resource to valuable chemicals. In this study, one-pot transformation of cellobiose into LA and FA was demonstrated, using a series of multiple-functional ionic liquid-based polyoxometalate (IL-POM) hybrids as catalytic materials. These IL-POMs not only markedly promoted the production of valuable chemicals including LA, FA and monosaccharides with high selectivities, but also provided great convenience of the recovery and the reuse of the catalytic materials in an environmentally friendly manner. Cellobiose conversion of 100%, LA selectivity of 46.3%, and FA selectivity of 26.1% were obtained at 423?K and 3?MPa for 3?h in presence of oxygen. A detailed catalytic mechanism for the one-pot transformation of cellobiose was also presented.
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Composition-controlled synthesis of carbon-supported Pt-Co alloy nanoparticles and the origin of their ORR activity enhancement.
Phys Chem Chem Phys
PUBLISHED: 08-08-2014
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The ability to precisely tune the chemical compositions and electronic structures of nanoalloy catalysts is essential to achieve the goals of high activity and selectivity for the oxygen reduction reaction (ORR) on the catalysts by design. In this work, we synthesized carbon-supported Pt-Co alloy nanoparticles with controlled bimetallic compositions (Pt/Co atomic ratio = 81?:?19, 76?:?24, 59?:?41, 48?:?52, 40?:?60 and 26?:?74) by regulating solution pH and the amount of Pt and Co precursor salts to elucidate the effect of catalyst composition on ORR activity. The obtained Pt-Co alloy nanoparticles have face-centred cubic (fcc) structures and are well-dispersed on the surface of the carbon support with a narrow particle size distribution (2-4 nm diameters). The electrocatalysis experiments in alkaline solution reveal a strong correlation between ORR activity and the alloy composition of the catalysts. Interestingly, the mass-specific activities of the catalysts manifest a typical double-volcano plot as a function of alloy composition. In this Pt-Co alloy series, the catalyst with a Pt?:?Co atomic ratio of 76?:?24 exhibits the best ORR performance, which is remarkably higher than that of the commercial Pt/C (E-TEK). X-ray photoelectron spectroscopy (XPS) measurements demonstrate that the electronic structures of these catalysts can be tuned by controlling their alloy compositions, which are highly correlated with the trends in ORR activity. The origin of the enhancement in ORR activity may be strongly related to the unique chemical surface structures of the catalysts.
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Surfactant media to grow new crystalline cobalt 1,3,5-benzenetricarboxylate metal-organic frameworks.
Inorg Chem
PUBLISHED: 08-07-2014
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In this report, three new metal-organic frameworks (MOFs), [Co3(?3-OH)(HBTC)(BTC)2Co(HBTC)]·(HTEA)3·H2O (NTU-Z30), [Co(BTC)]·HTEA·H2O (NTU-Z31), [Co3(BTC)4]·(HTEA)4 (NTU-Z32), where H3BTC = 1,3,5-benzenetricarboxylic acid, TEA = triethylamine, and NTU = Nanyang Technological University, have been successfully synthesized under surfactant media and have been carefully characterized by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, and IR spectromtry. NTU-Z30 has an unusual trimeric [Co3(?3-OH)(COO)7] secondary building unit (SBU), which is different from the well-known trimeric [Co3O(COO)6] SBU. The topology studies indicate that NTU-Z30 and NTU-Z32 possess two new topologies, 3,3,6,7-c net and 2,8-c net, respectively, while NTU-Z31 has a known topology rtl type (3,6-c net). Magnetic analyses show that all three materials have weak antiferromagnetic behavior. Furthermore, NTU-Z30 has been selected as the heterogeneous catalyst for the aerobic epoxidation of alkene, and our results show that this material exhibits excellent catalytic activity as well as good stability. Our success in growing new crystalline cobalt 1,3,5-benzenetricarboxylate MOFs under surfactant media could pave a new road to preparing new diverse crystalline inorganic materials through a surfactant-thermal method.
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Epigenetic silencing of HDAC1 by miR-449a upregulates Runx2 and promotes osteoblast differentiation.
Int. J. Mol. Med.
PUBLISHED: 07-22-2014
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Human?induced pluripotent (iPS) cells can be induced to differentiate into osteoblasts, but the process is inefficient and time?consuming. Previous studies indicated a close association between the expression of Runx2 and osteoblast differentiation, and established that the transcriptional activation of the Runx2 gene was closely associated with histone acetylation. microRNA?449a (miR?449a) represses HDAC1 expression, thereby regulating histone acetylation. In the present study, whether the expression of miR?449a enhanced the generation of osteoblasts from human iPS cells was investigated. Introduction of miR?449a into human iPS cells resulted in the expression of osteoblast markers after only four days, compared to eight days for untransfected human iPS cells. Differentiation to osteoblasts was associated with a reduction in HDAC1 expression, and higher levels of histone acetylation, particularly at the binding sites on the Runx2 promoter in the human miR?449a?transfected iPS cells. Silencing of endogenous HDAC1 expression by exogenous miR?449a therefore maintains histone acetylation status, stimulates Runx2 gene expression and rapidly promotes osteoblast differentiation.
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Shorter telomere length in peripheral blood leukocytes is associated with childhood autism.
Sci Rep
PUBLISHED: 07-03-2014
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Telomeres are protective chromosomal structures that play a key role in preserving genomic stability. Epidemiologic studies have shown that the abnormal telomere length in leukocytes is associated with some mental disorders and age-related diseases. However, the association between leukocyte telomere length and autism has not been investigated. Here we investigated the possible association between relative telomere length (RTL) in peripheral blood leukocytes and childhood autism by using an established real-time polymerase chain reaction method. We observed significantly shorter RTL in patients with childhood autism than in controls (p = 0.006). Individuals with shorter RTL had a significantly increased presence of childhood autism compared with those who had long RTL. In patients, we found that family training interventions have a significant effect on telomere length (P = 0.012), but no correlations between RTL and clinical features (paternal age, maternal age, age of onset, illness of duration, CARS score and ABC score) were observed in this study. These results provided the first evidence that shorter leukocytes telomere length is significantly associated with childhood autism. The molecular mechanism underlying telomere length may be implicated in the development of autism.
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A Cost-Effective 3D Hydrogen Evolution Cathode with High Catalytic Activity: FeP Nanowire Array as the Active Phase.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 07-03-2014
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Iron is the cheapest and one of the most abundant transition metals. Natural [FeFe]-hydrogenases exhibit remarkably high activity in hydrogen evolution, but they suffer from high oxygen sensitivity and difficulty in scale-up. Herein, an FeP nanowire array was developed on Ti plate (FeP NA/Ti) from its ?-FeOOH NA/Ti precursor through a low-temperature phosphidation reaction. When applied as self-supported 3D hydrogen evolution cathode, the FeP NA/Ti electrode shows exceptionally high catalytic activity and good durability, and it only requires overpotentials of 55 and 127?mV to afford current densities of 10 and 100?mA?cm(2) , respectively. The excellent electrocatalytic performance is promising for applications as non-noble-metal HER catalyst with a high performance-price ratio in electrochemical water splitting for large-scale hydrogen fuel production.
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School Climate and Delinquency Among Chinese Adolescents: Analyses of Effortful Control as a Moderator and Deviant Peer Affiliation as a Mediator.
J Abnorm Child Psychol
PUBLISHED: 06-26-2014
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School climate is the quality and character of school life and reflects the norms, goals, values, interpersonal relationships, teaching and learning practices, and the organizational structure of a school. There is substantial literature documenting the negative association between positive school climate and adolescent delinquency, but little is known about the moderating and mediating mechanisms underlying this relationship. The aim of this study was to examine whether the direct and indirect pathways between school climate and adolescent delinquency would be moderated by effortful control. A sample of 2,758 Chinese adolescents (M age?=?13.53 years, SD?=?1.06) from 10 middle schools completed anonymous questionnaires regarding school climate, effortful control, deviant peer affiliation, and delinquency. After gender, age, geographical area, and socioeconomic status were included as covariates, the results revealed that school climate was significantly associated with adolescent delinquent behavior. This direct association was moderated by effortful control, such that the negative relationship between positive school climate and delinquency was only significant among adolescents low in effortful control. Moreover, the indirect association between school climate and delinquency via deviant peer affiliation was also moderated by effortful control. Specifically, the moderating effect of effortful control was not only manifested in the relationship between school climate and deviant peer affiliation, but also in the relationship between deviant peer affiliation and delinquency. These findings contribute to understanding the mechanisms through which positive school climate might reduce delinquent behavior and have important implications for prevention efforts aimed at diminishing adolescent delinquency.
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Knowledge, attitudes and practices relating to influenza A(H7N9) risk among live poultry traders in Guangzhou City, China.
BMC Infect. Dis.
PUBLISHED: 05-20-2014
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Live poultry traders (LPTs) have greater risk to avian influenza due to occupational exposure to poultry. This study investigated knowledge, attitudes and practices of LPTs relating to influenza A (H7N9).
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Structural insight into autoinhibition and histone H3-induced activation of DNMT3A.
Nature
PUBLISHED: 05-01-2014
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DNA methylation is an important epigenetic modification that is essential for various developmental processes through regulating gene expression, genomic imprinting, and epigenetic inheritance. Mammalian genomic DNA methylation is established during embryogenesis by de novo DNA methyltransferases, DNMT3A and DNMT3B, and the methylation patterns vary with developmental stages and cell types. DNA methyltransferase 3-like protein (DNMT3L) is a catalytically inactive paralogue of DNMT3 enzymes, which stimulates the enzymatic activity of Dnmt3a. Recent studies have established a connection between DNA methylation and histone modifications, and revealed a histone-guided mechanism for the establishment of DNA methylation. The ATRX-DNMT3-DNMT3L (ADD) domain of Dnmt3a recognizes unmethylated histone H3 (H3K4me0). The histone H3 tail stimulates the enzymatic activity of Dnmt3a in vitro, whereas the molecular mechanism remains elusive. Here we show that DNMT3A exists in an autoinhibitory form and that the histone H3 tail stimulates its activity in a DNMT3L-independent manner. We determine the crystal structures of DNMT3A-DNMT3L (autoinhibitory form) and DNMT3A-DNMT3L-H3 (active form) complexes at 3.82 and 2.90 Å resolution, respectively. Structural and biochemical analyses indicate that the ADD domain of DNMT3A interacts with and inhibits enzymatic activity of the catalytic domain (CD) through blocking its DNA-binding affinity. Histone H3 (but not H3K4me3) disrupts ADD-CD interaction, induces a large movement of the ADD domain, and thus releases the autoinhibition of DNMT3A. The finding adds another layer of regulation of DNA methylation to ensure that the enzyme is mainly activated at proper targeting loci when unmethylated H3K4 is present, and strongly supports a negative correlation between H3K4me3 and DNA methylation across the mammalian genome. Our study provides a new insight into an unexpected autoinhibition and histone H3-induced activation of the de novo DNA methyltransferase after its initial genomic positioning.
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Epigallocatechin-3-gallate (EGCG)-stabilized selenium nanoparticles coated with Tet-1 peptide to reduce amyloid-? aggregation and cytotoxicity.
ACS Appl Mater Interfaces
PUBLISHED: 05-01-2014
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Alzheimer's disease (AD), the most common neurodegenerative disease, is caused by an accumulation of amyloid-? (A?) plaque deposits in the brains. Evidence is increasingly showing that epigallocatechin-3-gallate (EGCG) can partly protect cells from A?-mediated neurotoxicity by inhibiting A? aggregation. In order to better understand the process of A? aggregation and amyloid fibril disaggregation and reduce the cytotoxicity of EGCG at high doses, we attached EGCG onto the surface of selenium nanoparticles (EGCG@Se). Given the low delivery efficiency of EGCG@Se to the targeted cells and the involvement of selenoprotein in antioxidation and neuroprotection, which are the key factors for preventing the onset and progression of AD, we synthesized EGCG-stabilized selenium nanoparticles coated with Tet-1 peptide (Tet-1-EGCG@Se, a synthetic selenoprotein analogue), considering the affinity of Tet-1 peptide to neurons. We revealed that Tet-1-EGCG@Se can effectively inhibit A? fibrillation and disaggregate preformed A? fibrils into nontoxic aggregates. In addition, we found that both EGCG@Se and Tet-1-EGCG@Se can label A? fibrils with a high affinity, and Tet-1 peptides can significantly enhance the cellular uptake of Tet-1-EGCG@Se in PC12 cells rather than in NIH/3T3 cells.
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Oral appliance effectively reverses Muller's maneuver-induced upper airway collapsibility in obstructive sleep apnea and hypopnea syndrome.
Sleep Breath
PUBLISHED: 04-25-2014
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To verify the effects of oral appliance (OA) on upper airway morphology under intraluminal pressure, identify specific sites of upper airway collapsibility that can be reversed by OAs, and determine the relationship between OA efficacy and dynamic upper airway changes using computed tomography (CT) with Muller's maneuver.
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Superhydrophobic Surface Enhanced Raman Scattering Sensing using Janus Particle Arrays Realized by Site-Specific Electrochemical Growth.
J Mater Chem C Mater Opt Electron Devices
PUBLISHED: 04-22-2014
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Site-specific electrochemical deposition is used to prepare polystyrene (PS)-Ag Janus particle arrays with superhydrophobic properties. The analyte molecules can be significantly enriched using the superhydrophobic property of the PS-Ag Janus particle array before SERS detections, enabling an extremely sensitive detection of molecules in a highly diluted solution (e.g., femtomolar level). This superhydrophobic surface enhanced Raman scattering sensing concept described here is of critical significance in biosensing and bioanalysis. Most importantly, the site-specific electrochemical growth method we developed here is a versatile approach that can be used to prepare Janus particle arrays with different properties for various applications.
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The PHD1 finger of KDM5B recognizes unmodified H3K4 during the demethylation of histone H3K4me2/3 by KDM5B.
Protein Cell
PUBLISHED: 04-16-2014
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KDM5B is a histone H3K4me2/3 demethylase. The PHD1 domain of KDM5B is critical for demethylation, but the mechanism underlying the action of this domain is unclear. In this paper, we observed that PHD1KDM5B interacts with unmethylated H3K4me0. Our NMR structure of PHD1KDM5B in complex with H3K4me0 revealed that the binding mode is slightly different from that of other reported PHD fingers. The disruption of this interaction by double mutations on the residues in the interface (L325A/D328A) decreases the H3K4me2/3 demethylation activity of KDM5B in cells by approximately 50% and increases the transcriptional repression of tumor suppressor genes by approximately twofold. These findings imply that PHD1KDM5B may help maintain KDM5B at target genes to mediate the demethylation activities of KDM5B.
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Metallic Nanocatalysis: An Accelerating Seamless Integration with Nanotechnology.
Small
PUBLISHED: 03-28-2014
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Rapidly growing research interests surround heterogeneous nanocatalysis, in which metal nanoparticles (NPs) play a pivotal role as structure-sensitive active centers. With advances in nanotechnology, the morphology of metal NPs can be precisely controlled, which can provide well-defined models of nanocatalysts for understanding and optimizing the structure-reactivity correlations and the catalytic mechanisms. Benefiting from this, further credible evidence can be acquired on well-defined nanocatalysts rather than common multiphase systems, which is of great significance for the design and practical application of active metal nanocatalysts. Numerous studies demonstrate that enhanced structure-sensitive catalytic activity and selectivity are dependent not only on an increased surface-to-volume ratio and special surface atom arrangements, but also on tailored metal-metal and metal-organic-ligand interfaces, which is ascribed to the size, shape, composition, and ligand effects. Size-reactivity relationships and underlying size-dependent metal-oxide interactions are observed in many reactions. For bimetallic nanocatalysts, the composition and nanostructure play critical roles in regulating reactivities. Crystal facets favor individual catalytic selectivity and rates via distinct reaction pathways occurring on diverse atomic arrangements, both to low-index and high-index facets. High-index facets exhibit superior reactivities owing to their high-energy active sites, which facilitate rapid bond-breaking and new bond generation. Additionally, organic ligands may enhance the catalytic activity and selectivity of metal nanocatalysts via changing the adsorption energies of reactants and/or reaction energy barriers. Furthermore, atomically dispersed metals, especially single-atom metallic catalysts, have emerged recently, which can achieve better specific catalytic activity compared to conventional nanostructured metallic catalysts due to the low-coordination environment, stronger interaction with supports, and maximum service efficiency. Here, recent progress in shaped metallic nanocatalysts is examined and several parameters are discussed, as well as finally highlighting single-atom metallic catalysts and some perspectives on nanocatalysis. The integration of nanotechnology and nanocatalysis has been shaping up and, no doubt, the combination of sensitive characterization techniques and quantum calculations will play more important roles in such processes.
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Dark-field illumination on zero-mode waveguide/microfluidic hybrid chip reveals T4 replisomal protein interactions.
Nano Lett.
PUBLISHED: 03-24-2014
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The ability of zero-mode waveguides (ZMWs) to guide light energy into subwavelength-diameter cylindrical nanoapertures has been exploited for single-molecule fluorescence studies of biomolecules at micromolar concentrations, the typical dissociation constants for biomolecular interactions. Although epi-fluorescence microscopy is now adopted for ZMW-based imaging as an alternative to the commercialized ZMW imaging platform, its suitability and performance awaits rigorous examination. Here, we present conical lens-based dark-field fluorescence microscopy in combination with a ZMW/microfluidic chip for single-molecule fluorescence imaging. We demonstrate that compared to epi-illumination, the dark-field configuration displayed diminished background and noise and enhanced signal-to-noise ratios. This signal-to-noise ratio for imaging using the dark-field setup remains essentially unperturbed by the presence of background fluorescent molecules at micromolar concentration. Our design allowed single-molecule FRET studies that revealed weak DNA-protein and protein-protein interactions found with T4 replisomal proteins.
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Quinone derivatives from the genus Rubia and their bioactivities.
Chem. Biodivers.
PUBLISHED: 03-18-2014
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The extracts and phytochemicals of the genus Rubia have drawn much attention due to their potent effects; among them, naphthoquinone and cyclopeptide derivatives, with significant biological activities, have great potential to be developed to new drugs. This review updates and compiles a total of 142 quinone derivatives including anthraquinone and naphthoquinone derivatives, occuring in twelve Rubia species. These compounds were listed together with their sources, melting points, bioactivities, as well as 112 corresponding references. Furthermore, the structure?activity relationships of these quinone derivatives were discussed.
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Induction of E-cadherin+ human amniotic fluid cell differentiation into oocyte-like cells via culture in medium supplemented with follicular fluid.
Mol Med Rep
PUBLISHED: 03-17-2014
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Pluripotent human amniotic fluid cells (HuAFCs) can differentiate into various types of somatic cell in vitro. However, their differentiation into oocyte-like cells has never been described to the best of our knowledge. In the present study, differentiation of E-cadherin+ and E-cadherin- HuAFC sub-populations into oocyte-like cells was induced via culture in medium containing bovine follicular fluid and ?-mercaptoethanol. The E-cadherin+ HuAFCs expressed DAZL highly. Post-induction, cells with an oocyte-like phenotype were found among the E-cadherin+ HuAFCs, expressing markers specific to germ cells and oocytes (VASA, ZP3 and GDF9) and meiosis (DMC1 and SCP3). When specific small interfering RNA (siRNA) was used to suppress E-cadherin in the E-cadherin+ HuAFCs, the levels of DAZL expression were reduced. Post-induction, the morphology of the siRNA?E?cadherin HuAFCs was poorer and the expression levels of germ cell-specific markers were lower compared with those of the siRNA-mock HuAFCs. Therefore, E-cadherin+ HuAFCs could be more easily induced to differentiate into oocyte-like cells by bovine follicular fluid and ?-mercaptoethanol. In addition, the E-cadherin+ HuAFCs exhibited potential characteristics of DAZL protein expression, and thus it was conjectured that bovine follicular fluid acts on DAZL protein and promotes E-cadherin+ HuAFC differentiation into oocyte-like cells.
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Combinatorial development of bulk metallic glasses.
Nat Mater
PUBLISHED: 03-05-2014
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The identification of multicomponent alloys out of a vast compositional space is a daunting task, especially for bulk metallic glasses composed of three or more elements. Despite an increasing theoretical understanding of glass formation, bulk metallic glasses are predominantly developed through a sequential and time-consuming trial-and-error approach. Even for binary systems, accurate quantum mechanical approaches are still many orders of magnitude away from being able to simulate the relatively slow kinetics of glass formation. Here, we present a high-throughput strategy where ?3,000 alloy compositions are fabricated simultaneously and characterized for thermoplastic formability through parallel blow forming. Using this approach, we identified the composition with the highest thermoplastic formability in the glass-forming system Mg-Cu-Y. The method provides a versatile toolbox for unveiling complex correlations of material properties and glass formation, and should facilitate a drastic increase in the discovery rate of metallic glasses.
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Chronic administration of ketamine mimics the perturbed sense of body ownership associated with schizophrenia.
Psychopharmacology (Berl.)
PUBLISHED: 03-04-2014
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Subanaesthetic ketamine infusion in healthy volunteers induces experiences redolent of early psychosis, including changes in the experience of one's own body. It is not clear, however, whether repeated self-administration of ketamine has a sustained effect on body representation that is comparable to that found during acute administration.
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The effect of structural empowerment and organizational commitment on Chinese nurses' job satisfaction.
Appl Nurs Res
PUBLISHED: 02-15-2014
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The purposes of this study were (1) to examine the level of structural empowerment, organizational commitment and job satisfaction in Chinese nurses; and (2) to investigate the relationships among the three variables.
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Colloidal PbSe quantum dot-solution-filled liquid-core optical fiber for 1.55 ?m telecommunication wavelengths.
Nanotechnology
PUBLISHED: 02-14-2014
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We have studied the optical properties of PbSe colloidal quantum dot-solution filled hollow core multimode silica waveguides as a function of quantum dot-solution concentration, waveguide length, optical pump power and choice of organic solvent in order to establish the conditions to maximize near infrared spontaneous emission intensities. The optical performance was compared and showed good agreement with a simple three level system model for the quantum dots confined in an optical waveguide. Near infrared absorption-free solvent of tetrachlorethylene was confirmed to be a good candidate for the waveguide medium due to the enhancement of output intensity from the liquid-core fiber compared to the performance in toluene-based fiber. This approach demonstrates a useful method for early characterization of quantum dot materials in a waveguide test-bed with minimal material processing on the colloidal nanoparticles.
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Surface coordination polymerization of ethylene by hydrozirconation-immobilized metallocene.
Macromol Rapid Commun
PUBLISHED: 02-12-2014
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Hydrozirconation on vinyl-terminated substrates (silicon wafer and nanosilica sphere) is employed as an efficient way for immobilization of zirconocene catalyst through Zr-C bonds, which is applied in surface coordination ethylene polymerization producing surface-tethered polyethylene (PE). The formation of Zr-C ? bond induced by hydrozirconation provides an initiator precursor for growing a layer of PE covalently linked onto substrates. The results from SEM, AFM, and TEM show that the surface polymerization is controlled by hydrozirconation. Surface pattern or core-shell structure with crystalline PE coating can be formed, when silicon wafer is selectively functionalized with vinyl-groups or vinyl-modified nanosilica is applied. It is believed that hydrozirconation for the synthesis of zirconocene initiator can be a versatile route to prepare polyolefin hybrid materials.
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A ruthenium(II) complex capable of inducing and stabilizing bcl-2 G-quadruplex formation as a potential cancer inhibitor.
J. Inorg. Biochem.
PUBLISHED: 02-12-2014
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Two ruthenium(II) complexes (Ru-complexes) were synthesized and characterized in this study. The selectivity and ability of the complexes to interact with bcl-2 DNA were investigated here. It turned out that [Ru(ip)3](ClO4)2·2H2O (complex 1, ip = 1H-iminazole [4,5-f][1,10] phenanthroline) could induce and stabilize the formations of G-quadruplexes more effectively than [Ru(pip)3](ClO4)2·2H2O (complex 2, pip = 2-phenylimidazo-[4,5-f][1,10]phenanthroline) did. Considering the important role of the Ru-complex ligand in inducing and stabilizing the formations of G-quadruplex in our previous studies, we speculate that the overlarge ligand of complex 2 may block its binding affinity for G-quadruplexes. Complex 1 also induced cell apoptosis in in vitro assays. In general, this study provided potentially important information for further development of the Ru-complexes as good inducers and stabilizers of bcl-2 G-quadruplex DNA for cancer treatment.
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[Renal expression of RANK-RANKL in a rat model of puromycin aminonucleoside nephropathy].
Nan Fang Yi Ke Da Xue Xue Bao
PUBLISHED: 01-28-2014
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To investigate RANK-RANKL expression in the kidneys of a rat model of puromycin aminonucleoside nephropathy (PAN).
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Standing surface acoustic wave (SSAW)-based microfluidic cytometer.
Lab Chip
PUBLISHED: 01-11-2014
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The development of microfluidic chip-based cytometers has become an important area due to their advantages of compact size and low cost. Herein, we demonstrate a sheathless microfluidic cytometer which integrates a standing surface acoustic wave (SSAW)-based microdevice capable of 3D particle/cell focusing with a laser-induced fluorescence (LIF) detection system. Using SSAW, our microfluidic cytometer was able to continuously focus microparticles/cells at the pressure node inside a microchannel. Flow cytometry was successfully demonstrated using this system with a coefficient of variation (CV) of less than 10% at a throughput of ~1000 events s(-1) when calibration beads were used. We also demonstrated that fluorescently labeled human promyelocytic leukemia cells (HL-60) could be effectively focused and detected with our SSAW-based system. This SSAW-based microfluidic cytometer did not require any sheath flows or complex structures, and it allowed for simple operation over a wide range of sample flow rates. Moreover, with the gentle, bio-compatible nature of low-power surface acoustic waves, this technique is expected to be able to preserve the integrity of cells and other bioparticles.
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Construction of functional tissue-engineered bone using cell sheet technology in a canine model.
Exp Ther Med
PUBLISHED: 01-09-2014
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The aim of the present study was to construct functional tissue-engineered bone with cell sheet technology and compare the efficacy of this method with that of traditional bone tissue engineering techniques. Canine bone mesenchymal stem cells (BMSCs) were isolated using density gradient centrifugation and then cultured. The BMSCs were induced to differentiate into osteoblasts and cultured in temperature-responsive culture dishes. The BMSCs detached automatically from the temperature-responsive culture dishes when the temperature was reduced to 20°C, forming an intact cell sheet. Demineralized bone matrix (DBM) and platelet-rich plasma (PRP) were prepared and used to construct a DBM/PRP/BMSC cell sheet/BMSC complex, which was implanted under the left latissimus dorsi muscle in a dog model. A DBM/PRP/BMSC complex was used as a control and implanted under the right latissimus dorsi muscle in the dog model. Immunoblot assays were performed to detect the levels of growth factors. Osteogenesis was observed to be induced significantly more effectively in the DBM/PRP/BMSC cell sheet/BMSC implants than in the DBM/PRP/BMSC implants. Immunoblot assay results indicated that the levels of the growth factors platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) in the experimental group were 3.2- and 2.5-fold higher compared with those in the control group, respectively. These results indicated that the BMSC cell sheets were functional and more effective than the control cell complex. Therefore, cell sheet technology may be used for the effective construction of functional tissue-engineered bone with ideal properties.
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Attenuation of A?25-35-induced parallel autophagic and apoptotic cell death by gypenoside XVII through the estrogen receptor-dependent activation of Nrf2/ARE pathways.
Toxicol. Appl. Pharmacol.
PUBLISHED: 01-02-2014
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Amyloid-beta (A?) has a pivotal function in the pathogenesis of Alzheimer's disease. To investigate A? neurotoxicity, we used an in vitro model that involves A?25-35-induced cell death in the nerve growth factor-induced differentiation of PC12 cells. A?25-35 (20?M) treatment for 24h caused apoptotic cell death, as evidenced by significant cell viability reduction, LDH release, phosphatidylserine externalization, mitochondrial membrane potential disruption, cytochrome c release, caspase-3 activation, PARP cleavage, and DNA fragmentation in PC12 cells. A?25-35 treatment led to autophagic cell death, as evidenced by augmented GFP-LC3 puncta, conversion of LC3-I to LC3-II, and increased LC3-II/LC3-I ratio. A?25-35 treatment induced oxidative stress, as evidenced by intracellular ROS accumulation and increased production of mitochondrial superoxide, malondialdehyde, protein carbonyl, and 8-OHdG. Phytoestrogens have been proved to be protective against A?-induced neurotoxicity and regarded as relatively safe targets for AD drug development. Gypenoside XVII (GP-17) is a novel phytoestrogen isolated from Gynostemma pentaphyllum or Panax notoginseng. Pretreatment with GP-17 (10?M) for 12h increased estrogen response element reporter activity, activated PI3K/Akt pathways, inhibited GSK-3?, induced Nrf2 nuclear translocation, augmented antioxidant responsive element enhancer activity, upregulated heme oxygenase 1 (HO-1) expression and activity, and provided protective effects against A?25-35-induced neurotoxicity, including oxidative stress, apoptosis, and autophagic cell death. In conclusion, GP-17 conferred protection against A?25-35-induced neurotoxicity through estrogen receptor-dependent activation of PI3K/Akt pathways, inactivation of GSK-3? and activation of Nrf2/ARE/HO-1 pathways. This finding might provide novel insights into understanding the mechanism for neuroprotective effects of phytoestrogens or gypenosides.
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?4 contributes to bladder urothelial carcinoma cell invasion and/or metastasis via regulation of E-cadherin and is a predictor of outcome in bladder urothelial carcinoma patients.
Eur. J. Cancer
PUBLISHED: 01-02-2014
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?4 is upregulated in several types of human cancer and possesses an oncogenic role. However, the abnormalities of ?4 and its underlying mechanisms in the pathogenesis of bladder urothelial carcinoma (BUC) remain unknown.
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Effects of Ciji Hua'ai Baosheng Granule Formula (CHBGF) on Life Time, Pathology, Peripheral Blood Cells of Tumor Chemotherapy Model Mouse with H22 Hepatoma Carcinoma Cells.
Afr J Tradit Complement Altern Med
PUBLISHED: 01-01-2014
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Ciji Hua'ai Baosheng Granule Formula (CHBGF) is a traditional Chinese empirical formula that can help the tumor patients who have received chemotherapy antagonize the toxin and side-effects so as to improve and prolong the life. This study is to evaluate the effects of CHBGF on improving life quality in terms of survival time, pathology of tumor tissue and ameliorating peripheral blood cells in mouse chemotherapy model with subcutaneous transplanted tumor or ascitic tumor of H22 hepatoma carcinoma cells at an overall level.
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The molecular epidemiological characteristics and genetic diversity of salmonella typhimurium in guangdong, china, 2007-2011.
PLoS ONE
PUBLISHED: 01-01-2014
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Salmonella enterica serovar Typhimurium is the most important serovar associated with human salmonellosis worldwide. Here we aimed to explore the molecular epidemiology and genetic characteristics of this serovar in Guangdong, China.
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Meta-analysis of peritumoural rCBV values derived from dynamic susceptibility contrast imaging in differentiating high-grade gliomas from intracranial metastases.
Int J Clin Exp Med
PUBLISHED: 01-01-2014
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In the preoperative period, it is very important to accurately differentiate high-grade gliomas from intracranial metastases, as treatment strategies vary. Hence we performed a meta-analysis to evaluate the sensitivity and specificity of peritumoural relative cerebral blood volume (rCBV) values derived from dynamic susceptibility contrast imaging (DSCI) in differentiating high-grade gliomas from intracranial metastases.
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Genome-Wide Association Studies Using Haplotypes and Individual SNPs in Simmental Cattle.
PLoS ONE
PUBLISHED: 01-01-2014
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Recent advances in high-throughput genotyping technologies have provided the opportunity to map genes using associations between complex traits and markers. Genome-wide association studies (GWAS) based on either a single marker or haplotype have identified genetic variants and underlying genetic mechanisms of quantitative traits. Prompted by the achievements of studies examining economic traits in cattle and to verify the consistency of these two methods using real data, the current study was conducted to construct the haplotype structure in the bovine genome and to detect relevant genes genuinely affecting a carcass trait and a meat quality trait. Using the Illumina BovineHD BeadChip, 942 young bulls with genotyping data were introduced as a reference population to identify the genes in the beef cattle genome significantly associated with foreshank weight and triglyceride levels. In total, 92,553 haplotype blocks were detected in the genome. The regions of high linkage disequilibrium extended up to approximately 200 kb, and the size of haplotype blocks ranged from 22 bp to 199,266 bp. Additionally, the individual SNP analysis and the haplotype-based analysis detected similar regions and common SNPs for these two representative traits. A total of 12 and 7 SNPs in the bovine genome were significantly associated with foreshank weight and triglyceride levels, respectively. By comparison, 4 and 5 haplotype blocks containing the majority of significant SNPs were strongly associated with foreshank weight and triglyceride levels, respectively. In addition, 36 SNPs with high linkage disequilibrium were detected in the GNAQ gene, a potential hotspot that may play a crucial role for regulating carcass trait components.
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White and grey matter changes in the language network during healthy aging.
PLoS ONE
PUBLISHED: 01-01-2014
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Neural structures change with age but there is no consensus on the exact processes involved. This study tested the hypothesis that white and grey matter in the language network changes during aging according to a "last in, first out" process. The fractional anisotropy (FA) of white matter and cortical thickness of grey matter were measured in 36 participants whose ages ranged from 55 to 79 years. Within the language network, the dorsal pathway connecting the mid-to-posterior superior temporal cortex (STC) and the inferior frontal cortex (IFC) was affected more by aging in both FA and thickness than the other dorsal pathway connecting the STC with the premotor cortex and the ventral pathway connecting the mid-to-anterior STC with the ventral IFC. These results were independently validated in a second group of 20 participants whose ages ranged from 50 to 73 years. The pathway that is most affected during aging matures later than the other two pathways (which are present at birth). The results are interpreted as showing that the neural structures which mature later are affected more than those that mature earlier, supporting the "last in, first out" theory.
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The effects of leaf roughness, surface free energy and work of adhesion on leaf water drop adhesion.
PLoS ONE
PUBLISHED: 01-01-2014
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The adhesion of water droplets to leaves is important in controlling rainfall interception, and affects a variety of hydrological processes. Leaf water drop adhesion (hereinafter, adhesion) depends not only on droplet formulation and parameters but also on the physical (leaf roughness) and physico-chemical (surface free energy, its components, and work-of-adhesion) properties of the leaf surface. We selected 60 plant species from Shaanxi Province, NW China, as experimental materials with the goal of gaining insight into leaf physical and physico-chemical properties in relation to the adhesion of water droplets on leaves. Adhesion covered a wide range of area, from 4.09 to 88.87 g/m(2) on adaxial surfaces and 0.72 to 93.35 g/m(2) on abaxial surfaces. Distinct patterns of adhesion were observed among species, between adaxial and abaxial surfaces, and between leaves with wax films and wax crystals. Adhesion decreased as leaf roughness increased (r =? -0.615, p = 0.000), but there were some outliers, such as Salix psammophila and Populus simonii with low roughness and low adhesion, and the abaxial surface of Hyoscyamus pusillus and the adaxial surface of Vitex negundo with high roughness and high adhesion. Meanwhile, adhesion was positively correlated with surface free energy (r = 0.535, p = 0.000), its dispersive component (r = 0.526, p = 0.000), and work of adhesion for water (r = 0.698, p = 0.000). However, a significant power correlation was observed between adhesion and the polar component of surface free energy (p = 0.000). These results indicated that leaf roughness, surface free energy, its components, and work-of-adhesion for water played important roles in hydrological characteristics, especially work-of-adhesion for water.
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Leukocyte mitochondrial DNA copy number in blood is not associated with major depressive disorder in young adults.
PLoS ONE
PUBLISHED: 01-01-2014
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Major depressive disorder (MDD) is the leading cause of disability worldwide, and has significant genetic predisposition. Mitochondria may have a role in MDD and so mitochondrial DNA (mtDNA) has been suggested as a possible biomarker for this disease. We aimed to test whether the mtDNA copy number of peripheral blood leukocytes is related to MDD in young adults.
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Long-term effects of liming on health and growth of a Masson pine stand damaged by soil acidification in Chongqing, China.
PLoS ONE
PUBLISHED: 01-01-2014
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In the last decades, the Masson pine (Pinus massoniana) forests in Chongqing, southwest China, have increasingly declined. Soil acidification was believed to be an important cause. Liming is widely used as a measure to alleviate soil acidification and its damage to trees, but little is known about long-term effects of liming on the health and growth of declining Masson pine forests. Soil chemical properties, health condition (defoliation and discoloration), and growth were evaluated following application of limestone powder (0 (unlimed control), 1, 2, 3, and 4 t ha(-1)) in an acidified and declining Masson pine stand at Tieshanping (TSP) of Chongqing. Eight years after liming, in the 0-20 cm and 20-40 cm mineral soil layers, soil pH values, exchangeable calcium (Ca) contents, and Ca/Al molar ratios increased, but exchangeable aluminum (Al) levels decreased, and as a result, length densities of living fine roots of Masson pine increased, with increasing dose. Mean crown defoliation of Masson pines (dominant, codominant and subdominant pines, according to Kraft classes 1-3) decreased with increasing dose, and it linearly decreased with length densities of living fine roots. However, Masson pines (Kraft classes 1-3) in all treatments showed no symptoms of discoloration. Mean current-year twig length, twig dry weight, needle number per twig, needle length per twig, and needle dry weight per twig increased with increasing dose. Over 8 years, mean height increment of Masson pines (Kraft classes 1-3) increased from 5.5 m in the control to 5.8, 6.9, 8.3, and 9.5 m in the 1, 2, 3, and 4 t ha(-1) lime treatments, and their mean DBH (diameter at breast height) increment increased from 3.1 to 3.2, 3.8, 4.9, and 6.2 cm, respectively. The values of all aboveground growth parameters linearly increased with length densities of living fine roots. Our results show that liming improved tree health and growth, and these effects increased with increasing dose.
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Cyclin D1 overexpression is associated with poor clinicopathological outcome and survival in oral squamous cell carcinoma in Asian populations: insights from a meta-analysis.
PLoS ONE
PUBLISHED: 01-01-2014
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The clinicopathological significance of cyclin D1 overexpression and prognosis of oral squamous cell carcinoma has not been fully quantified. We performed a comprehensive meta-analysis for evaluation of cyclin D1 overexpression in oral squamous cell carcinoma to determine the strength of this association.
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Interaction between 8-hydroxyquinoline ruthenium(ii) complexes and basic fibroblast growth factors (bFGF): inhibiting angiogenesis and tumor growth through ERK and AKT signaling pathways.
Metallomics
PUBLISHED: 12-16-2013
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Angiogenesis is crucial for tumor growth. Thus, inhibiting angiogenesis represents a promising avenue for preventing tumor growth. This study investigated the anti-angiogenesis and anti-tumor effects of 8-hydroxyquinoline ruthenium(ii) complexes [Ru(bpy)2(8-HQ)](+) (BQ) and [Ru(phen)2(8-HQ)](+) (PQ). The results showed that both compounds, especially PQ, suppressed the proliferation, migration, invasion, tube formation and microvessel growth of endothelial cells in vitro. PQ also inhibited tumor growth of human hepatocellular liver carcinoma cells (HepG2) in a mouse xenograft tumor model in vivo. To understand the mechanisms of how ruthenium(ii) complexes disrupt bFGF-induced angiogenesis and tumor growth, we have shown that (1) both compounds can interfere with the binding of bFGF to its cell surface receptors, thereby suppressing activation of bFGF-mediated signaling cascades; (2) PQ can induce tumor cell apoptosis. These effects might inhibit angiogenesis and tumor cell proliferation in tumor tissue. Taken together, our findings reveal that 8-hydroxyquinoline ruthenium(ii) complexes are specific inhibitors of bFGF-mediated angiogenesis, and may be a viable drug candidate in anti-angiogenesis and anti-tumor therapies.
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Interleukin-16 Gene Polymorphisms rs4778889, rs4072111, rs11556218, and Cancer Risk in Asian Populations: A Meta-Analysis.
Genet Test Mol Biomarkers
PUBLISHED: 12-13-2013
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Objectives: Some polymorphisms of the interleukin-16 (IL-16) gene are associated with various cancers. To resolve inconsistencies in published data, we performed a meta-analysis of studies of IL-16 polymorphisms and cancer risk. Materials and Methods: Seven eligible studies pooling 1678 cases and 1937 controls were quantitatively analyzed to evaluate three IL-16 polymorphisms (rs4778889, rs4072111, rs11556218) and cancer risk. Hardy-Weinberg equilibrium (HWE) for controls was evaluated by goodness-of-fit chi-squared tests. Odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated for each genetic model and allelic comparison. Data were pooled using fixed- or random-effects models depending on heterogeneity across studies. Results: Our meta-analysis demonstrated that the IL-16 polymorphism rs11556218 was significantly associated with increased susceptibility to cancer in several models, including allelic contrast (OR=1.307; 95% CI, 1.108-1.541), heterozygote contrast (OR=1.650; 95% CI, 1.424-1.911), and dominant model (OR=1.605; 95% CI, 1.391-1.845). The result remained consistent after adjustment for age and gender. No significant association was found between IL-16 polymorphisms rs4778889 rs4072111 and cancer risk. Conclusions: The rs11556218 T/G polymorphism of the IL-16 gene was significantly associated with elevated cancer risk in Asian populations. Our results warrant larger, better-designed studies, including a greater ethnic variety.
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Co6(?3-OH)6 cluster based coordination polymer as an effective heterogeneous catalyst for aerobic epoxidation of alkenes.
Dalton Trans
PUBLISHED: 12-06-2013
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A new hexaprismane Co(ii)6(?3-OH)6 cluster-based three-dimensional coordination polymer ({Co(?3-OH)(HCOO)0.72(CH3COO)0.28}n, ) was successfully synthesized and characterized with single-crystal XRD, IR spectra, TGA spectra and elemental analysis. was used as an effective heterogeneous catalyst for the aerobic epoxidation of various alkenes. For the catalytic epoxidation of trans-stilbene, the conversion and selectivity towards the epoxide reached 98.6 and 98.0%, respectively. Also, an average TOF of 22 h(-1) was obtained for the reaction. The results indicated that displayed excellent aerobic epoxidation activity among the reported coordination polymer materials, even rivaling the traditional heterogeneous cobalt catalysts. The influence of the reaction parameters such as temperature and oxygen flow rate for the epoxidation of the trans-stilbene were also studied in detail.
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Sub-micrometer-precision, three-dimensional (3D) hydrodynamic focusing via"microfluidic drifting".
Lab Chip
PUBLISHED: 11-28-2013
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In this article, we demonstrate single-layered, "microfluidic drifting" based three-dimensional (3D) hydrodynamic focusing devices with particle/cell focal positioning approaching submicron precision along both lateral and vertical directions. By systematically optimizing channel geometries and sample/sheath flow rates, a series of "microfluidic drifting" based 3D hydrodynamic focusing devices with different curvature angles are designed and fabricated. Their performances are then evaluated using confocal microscopy, fast camera imaging, and side-view imaging techniques. Using a device with a curvature angle of 180°, we have achieved a standard deviation of ±0.45 ?m in particle focal position and a coefficient of variation (CV) of 2.37% in flow cytometric measurements. To the best of our knowledge, this is the best CV that has been achieved using a microfluidic flow cytometry device. Moreover, the device showed the capability to distinguish 8 peaks when subjected to a stringent 8-peak rainbow calibration test, signifying the ability to perform sensitive, accurate tests similar to commercial flow cytometers. We have further tested and validated our device by detection of HEK-293 cells. With its advantages in simple fabrication (i.e., single-layered device), precise 3D hydrodynamic focusing (i.e., submicrometer precision along both lateral and vertical directions), and high detection resolution (i.e., low CV), our method could serve as an important basis for high-performance, mass-producible microfluidic flow cytometry.
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Theory and experiment on particle trapping and manipulation via optothermally generated bubbles.
Lab Chip
PUBLISHED: 11-26-2013
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We present a theoretical analysis and experimental demonstration of particle trapping and manipulation around optothermally generated bubbles. We show that a particle located within 500 ?m of a surface bubble can be attracted towards a bubble by drag force resulting from a convective flow. Once the particle comes in contact with the bubbles surface, a balance between surface tension forces and pressure forces traps the particle on the bubble surface, allowing the particle to move with the bubble without detaching. The proposed mechanism is confirmed by computational fluid dynamics simulations, force calculations, and experiments. Based on this mechanism, we experimentally demonstrated a novel approach for manipulating microparticles via optothermally generated bubbles. Using this approach, randomly distributed microparticles were effectively collected and carried to predefined locations. Single particles were also manipulated along prescribed trajectories. This bubble-based particle trapping and manipulation technique can be useful in applications such as micro assembly, particle concentration, and high-precision particle separation.
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Nurse burnout: Personal and environmental factors as predictors.
Int J Nurs Pract
PUBLISHED: 11-19-2013
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The aim of this study is to investigate the level of burnout of clinical nurses and to examine the influence of personal and environmental factors on nurse burnout. A total of 717 full-time nurses from six hospitals in Tianjin, China, completed five questionnaires: a demographic questionnaire, the Maslach Burnout Inventory, the General Self-Efficacy Scale, the Practice Environment Scale of the Nursing Work Index and the Nurse Job Stressor Scale. The participants had moderate levels of emotional exhaustion (mean score 23.95?±?11.11) and depersonalization (mean score 7.90?±?6.58) and a high level of reduced personal accomplishment (mean score 27.51?±?10.96). Both personal and environmental factors were correlated with nurse burnout; however, personal factors played bigger roles in predicting personal accomplishment, whereas environmental factors played bigger roles in predicting emotional exhaustion and depersonalization. In order to reduce nurse job burnout effectively, administrators should pay more attention to the improvement of nurses self-efficacy and professional nursing practice environment and the reduction of stressors.
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Phosphine-Catalyzed Reactions of Activated Olefins Tethered to Cycloalkanones. Substrate- and Solvent-Controlled Synthesis of Bicyclo[3.2.1]octanones, Mixed Acetals, and Morita-Baylis-Hillman Products.
Org. Lett.
PUBLISHED: 11-11-2013
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The n-Bu3P organocatalyzed reaction of cycloalkanones, i.e., cyclopentanones or 1,3-cyclopentanediones tethered to actived olefins, afforded selectively and in high yields three different types of products: bicyclo[3.2.1]octanones, mixed acetals, and Morita-Baylis-Hillman products. The progress of the reaction was closely related to the reaction medium and to the length of the tether located between the cyclopentanone (-dione) and the activated olefin.
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Crystal Structure of TET2-DNA Complex: Insight into TET-Mediated 5mC Oxidation.
Cell
PUBLISHED: 10-20-2013
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TET proteins oxidize 5-methylcytosine (5mC) on DNA and play important roles in various biological processes. Mutations of TET2 are frequently observed in myeloid malignance. Here, we present the crystal structure of human TET2 bound to methylated DNA at 2.02 Å resolution. The structure shows that two zinc fingers bring the Cys-rich and DSBH domains together to form a compact catalytic domain. The Cys-rich domain stabilizes the DNA above the DSBH core. TET2 specifically recognizes CpG dinucleotide and shows substrate preference for 5mC in a CpG context. 5mC is inserted into the catalytic cavity with the methyl group orientated to catalytic Fe(II) for reaction. The methyl group is not involved in TET2-DNA contacts so that the catalytic cavity allows TET2 to accommodate 5mC derivatives for further oxidation. Mutations of Fe(II)/NOG-chelating, DNA-interacting, and zinc-chelating residues are frequently observed in human cancers. Our studies provide a structural basis for understanding the mechanisms of TET-mediated 5mC oxidation.
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Computational studies of the glass-forming ability of model bulk metallic glasses.
J Chem Phys
PUBLISHED: 10-05-2013
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Bulk metallic glasses (BMGs) are produced by rapidly thermally quenching supercooled liquid metal alloys below the glass transition temperature at rates much faster than the critical cooling rate R(c) below which crystallization occurs. The glass-forming ability of BMGs increases with decreasing R(c), and thus good glass-formers possess small values of R(c). We perform molecular dynamics simulations of binary Lennard-Jones (LJ) mixtures to quantify how key parameters, such as the stoichiometry, particle size difference, attraction strength, and heat of mixing, influence the glass-formability of model BMGs. For binary LJ mixtures, we find that the best glass-forming mixtures possess atomic size ratios (small to large) less than 0.92 and stoichiometries near 50:50 by number. In addition, weaker attractive interactions between the smaller atoms facilitate glass formation, whereas negative heats of mixing (in the experimentally relevant regime) do not change R(c) significantly. These results are tempered by the fact that the slowest cooling rates achieved in our simulations correspond to ~10(11) K/s, which is several orders of magnitude higher than R(c) for typical BMGs. Despite this, our studies represent a first step in the development of computational methods for quantitatively predicting glass-formability.
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Inhibition of tumor growth and vasculature and fluorescence imaging using functionalized ruthenium-thiol protected selenium nanoparticles.
Biomaterials
PUBLISHED: 10-03-2013
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Here we reported the high tumor targeting efficacy of luminescent Ru(II)-thiols protected selenium nanoparticles (Ru-MUA@Se). We have shown that a dual-target inhibitor Ru-MUA@Se directly suppress the tumor growth but also block blood-vessel growth. We also determined that the nanoparticles entered the cells via clathrin-mediated endocytosis pathway. In a xenograft HepG2 tumor model, we found that Ru-MUA@Se effectively inhibited tumor angiogenesis and suppressed tumor growth with low side effects using metronomic chemotherapy with Ru-MUA@Se. In vivo investigation of nanoparticles on nude mice bearing HepG2 cancer xenografts confirmed that Ru-MUA@Se nanoparticles possessed high tumor-targeted fluorescence imaging, exhibited enhanced antitumor efficacy and decreased systemic toxicity. Moreover, Ru-MUA@Se not only significantly induced dose-dependent disruption of mitochondrial membrane potential in HepG2 cells after 24 h treatment, but it also enhanced reactive oxygen species (ROS) generation. Our results suggest that the potential application of these Ru-MUA@Se nanoparticles in targeting cancer imaging and chemotherapy.
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Mechanistic insights into CED-4-mediated activation of CED-3.
Genes Dev.
PUBLISHED: 09-26-2013
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Programmed cell death in Caenorhabditis elegans requires activation of the caspase CED-3, which strictly depends on CED-4. CED-4 forms an octameric apoptosome, which binds the CED-3 zymogen and facilitates its autocatalytic maturation. Despite recent advances, major questions remain unanswered. Importantly, how CED-4 recognizes CED-3 and how such binding facilitates CED-3 activation remain completely unknown. Here we demonstrate that the L2 loop of CED-3 directly binds CED-4 and plays a major role in the formation of an active CED-4-CED-3 holoenzyme. The crystal structure of the CED-4 apoptosome bound to the L2 loop fragment of CED-3, determined at 3.2 Å resolution, reveals specific interactions between a stretch of five hydrophobic amino acids from CED-3 and a shallow surface pocket within the hutch of the funnel-shaped CED-4 apoptosome. Structure-guided biochemical analysis confirms the functional importance of the observed CED-4-CED-3 interface. Structural analysis together with published evidence strongly suggest a working model in which two molecules of CED-3 zymogen, through specific recognition, are forced into the hutch of the CED-4 apoptosome, consequently undergoing dimerization and autocatalytic maturation. The mechanism of CED-3 activation represents a major revision of the prevailing model for initiator caspase activation.
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Induction of estrogen-sensitive epithelial cells derived from human-induced pluripotent stem cells to repair ovarian function in a chemotherapy-induced mouse model of premature ovarian failure.
DNA Cell Biol.
PUBLISHED: 09-14-2013
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The incidence of premature ovarian failure (POF), a condition causing amenorrhea and hypergonadotropic hypoestrogenism in women before the age of 40, has been increasing in recent years. As an irreversible pathological change, improved treatment strategies for this disease are urgently needed. In this study, a type of microRNA (miR-17-3p) was used to guide the differentiation of human-induced pluripotent stem (iPS) cells into hormone-sensitive ovarian epithelial (OSE)-like cells in vitro. To prevent their morphological transformation into fibroblast-like cells, MiR-17-3p, a microRNA that suppresses vimentin expression, was transfected into human iPS cells. Subsequently, these cells were successfully induced into OSE-like cells in vitro after treatment with estrogen and cell growth factors. Compared with controls, iPS cells transfected with miR-17-3p expressed higher levels of epithelial markers (cytokeratin 7, AE1, AE3, and E-cadherin) and estrogen receptors (ER? and ER?) while levels of mesenchymal markers (fibronectin, vimentin, and N-cadherin) lowered after the induction. The human iPS cell-derived OSE-like cells were then injected into cyclophosphamide-induced POF model mice to determine their potential benefit as grafts to repair ovarian tissues. The OSE-like cells survived within POF mouse ovaries for at least 14 days in vivo. Compared with the negative controls, expressions of cytokeratin 7 and ER? proteins were elevated while fibronectin and vimentin levels in ovarian tissues were downregulated in the OSE-like cell transplantation group. Moreover, the ovarian weight and plasma E2 level increased over time in the transplantation with OSE-like cells, compared with control groups. Hence, we can draw the conclusion that iPS cells can be induced to differentiate into OSE-like cells in vitro.
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Molecular detection of human parechovirus in children with acute gastroenteritis in Guangzhou, China.
Arch. Virol.
PUBLISHED: 08-09-2013
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Human parechoviruses (HPeVs) are widespread pathogens causing a wide spectrum of diseases. The prevalence and genetic diversity of HPeV in children with acute diarrhea in China is not well known. The purpose of this study was to investigate the epidemiological characteristics of HPeV in Guangzhou, China. A total of 328 stool specimens collected from children under the age of 5 years with acute diarrhea were tested for the presence of HPeV. Of these, 44 (13.4 %, 44/328) were HPeV positive, with the majority of the infected children (97.7 %, 43/44) being younger than two years of age. HPeV was more frequently detected during July and August. The epidemiological profile of co-infections was similar to that observed in a previous study. Six different HPeV genotypes, including HPeV1, -3, -4, -5, -6, and -14, were identified, and of these, HPeV14, a rarely reported genotype, was reported for the first time in children with acute gastroenteritis in China. In summary, this study clearly demonstrated that HPeV circulating in Guangzhou, China, is genetically diverse, including six genotypes, and it provides useful epidemiological data on the features of HPeV infection in this area.
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Depletion effect and biomembrane budding.
J Biol Phys
PUBLISHED: 06-23-2013
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Depletion effects are well known to lead to phase separation in microsystems consisting of large and small particles with short-range repulsive interactions that act over macromolecular length scales. The equilibrium mechanics between an enveloped colloidal particle and a biomembrane caused by entropy is investigated by using a continuum model. We show that the favorable contact energy stems from entropy, which is sufficient to drive engulfment of the colloidal particle, and deformation of the biomembrane determines the resistance to the engulfment of the colloidal particle. The engulfment process depends on the ratio of the radii of the larger particle and smaller particles and the bending rigidity. The results show insights into the effects of depletion on biomembrane budding and nanoparticle transportation by a vesicle.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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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.