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Find video protocols related to scientific articles indexed in Pubmed.
Structure and Dynamics of Ferro- and Ferri-Cyanide Anions in Water and Heavy Water: an Insight by MD Simulations and 2D IR Spectroscopy.
J Phys Chem B
PUBLISHED: 11-20-2014
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Combined computational and experimental techniques were employed to investigate at microscopic level the structural and dynamic properties of ferro- and ferricyanide ions in aqueous solution. The characterization of the structural patterns and multi-scale dynamics taking place within the first solvation spheres in water and heavy water solvents was first achieved through extensive molecular dynamics simulations, performed with refined force fields, specifically parameterized for the cyanide ions under investigation. The information gained about the solute-solvent interactions is then validated through the successful comparison of computed and measured waiting-time-dependent 2D IR spectra. The vibrational patterns resulting from 2D IR measurements were rationalized in terms of the interaction between the ion and the neighboring water molecules described by simulation. It was found that, within the first solvation sphere, the stronger interactions of the solvent with the ferro species are responsible for a delay in the relaxation dynamics, which becomes more and more evident on longer time scales.
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Ligand replacement induced chemiluminescence for selective detection of an organophosphorus pesticide using bifunctional Au-Fe3O4 dumbbell-like nanoparticles.
Chem. Commun. (Camb.)
PUBLISHED: 11-07-2014
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A facile ligand replacement induced chemiluminescence method is developed for selective detection of the organophosphorus pesticide parathion-methyl based on the use of bifunctional Au-Fe3O4 dumbbell-like nanoparticles to overcome the interference from coexisting substances in a real sample.
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Label-Free Surface-Enhanced Raman Scattering Imaging to Monitor the Metabolism of Antitumor Drug 6-Mercaptopurine in Living Cells.
Anal. Chem.
PUBLISHED: 11-06-2014
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The molecular processes of drugs from cellular uptake to intracellular distribution as well as the intracellular interaction with the target molecule are critically important for the development of new antitumor drugs. In this work, we have successfully developed a label-free surface-enhanced Raman scattering (SERS) technique to monitor and visualize the metabolism of antitumor drug 6-mercaptopurine in living cells. It has been clearly demonstrated that Au@Ag NPs exhibit an excellent Raman enhancement effect to both 6-mercaptopurine and its metabolic product 6-mercaptopurine-ribose. Their different ways to absorb at the surface of Au@Ag NPs lead to the obvious spectral difference for distinguishing the antitumor drug and its metabolite by SERS spectra. The Au@Ag NPs can easily pass through cell membranes in a large amount and sensitively respond to the biological conversion of 6-mercaptopurine in tumor cells. The Raman imaging can visualize the real-time distribution of 6-mercaptopurine and its biotransformation with the concentrations in tumor cells. The SERS-based method reported here is simple and efficient for the assessments of drug efficacy and the understanding of the molecular therapeutic mechanism of antitumor drugs at the cellular level.
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First Succinyl-Proteome Profiling of Extensively Drug-Resistant Mycobacterium tuberculosis Revealed Involvement of Succinylation in Cellular Physiology.
J. Proteome Res.
PUBLISHED: 11-04-2014
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Protein lysine succinylation, an emerging protein post-translational modification widespread among eukaryotic and prokaryotic cells, represents an important regulator of cellular processes. However, the extent and function of lysine succinylation in Mycobacterium tuberculosis, especially extensively drug-resistant strain, remain elusive. Combining protein/peptide prefractionation, immunoaffinity enrichment, and LC-MS/MS analysis, a total of 686 succinylated proteins and 1739 succinylation sites of M. tuberculosis were identified, representing the first global profiling of M. tuberculosis lysine succinylation. The identified succinylated proteins are involved in a variety of cellular functions such as metabolic processes, transcription, translation, and stress responses and exhibit different subcellular localization via GO, protein interaction network, and other bioinformatic analysis. Notably, proteins involved in protein biosynthesis and carbon metabolism are preferred targets of lysine succinylation. Moreover, two prevalent sequence patterns: EK(suc) and K*****K(suc), can be found around the succinylation sites. There are 109 lysine-succinylated homologues in E. coli, suggesting highly conserved succinylated proteins. Succinylation was found to occur at the active sites predicted by Prosite signature including Rv0946c, indicating that lysine succinylation may affect their activities. There is extensive overlapping between acetylation sites and succinylation sites in M. tuberculosis. Many M. tuberculosis metabolic enzymes and antibiotic resistance proteins were succinylated. This study provides a basis for further characterization of the pathophysiological role of lysine succinylation in M. tuberculosis.
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Architectural Design of Heterogeneous Metallic Nanocrystals-Principles and Processes.
Acc. Chem. Res.
PUBLISHED: 10-25-2014
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Conspectus Heterogeneous metal nanocrystals (HMNCs) are a natural extension of simple metal nanocrystals (NCs), but as a research topic, they have been much less explored until recently. HMNCs are formed by integrating metal NCs of different compositions into a common entity, similar to the way atoms are bonded to form molecules. HMNCs can be built to exhibit an unprecedented architectural diversity and complexity by programming the arrangement of the NC building blocks ("unit NCs"). The architectural engineering of HMNCs involves the design and fabrication of the architecture-determining elements (ADEs), i.e., unit NCs with precise control of shape and size, and their relative positions in the design. Similar to molecular engineering, where structural diversity is used to create more property variations for application explorations, the architectural engineering of HMNCs can similarly increase the utility of metal NCs by offering a suite of properties to support multifunctionality in applications. The architectural engineering of HMNCs calls for processes and operations that can execute the design. Some enabling technologies already exist in the form of classical micro- and macroscale fabrication techniques, such as masking and etching. These processes, when used singly or in combination, are fully capable of fabricating nanoscopic objects. What is needed is a detailed understanding of the engineering control of ADEs and the translation of these principles into actual processes. For simplicity of execution, these processes should be integrated into a common reaction system and yet retain independence of control. The key to architectural diversity is therefore the independent controllability of each ADE in the design blueprint. The right chemical tools must be applied under the right circumstances in order to achieve the desired outcome. In this Account, after a short illustration of the infinite possibility of combining different ADEs to create HMNC design variations, we introduce the fabrication processes for each ADE, which enable shape, size, and location control of the unit NCs in a particular HMNC design. The principles of these processes are discussed and illustrated with examples. We then discuss how these processes may be integrated into a common reaction system while retaining the independence of individual processes. The principles for the independent control of each ADE are discussed in detail to lay the foundation for the selection of the chemical reaction system and its operating space.
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Theory of strain tuning fine structure splitting in self-assembled InAs/GaAs quantum dots.
J Phys Condens Matter
PUBLISHED: 10-23-2014
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We analytically derive the change in exciton fine structure splitting (FSS) under external stresses in self-assembled InAs/GaAs quantum dots, using the Bir-Pikus model. We find that the FSS change is mainly due to the strain-induced valence band mixing and valence-conduction band coupling. The exciton polarization angle under strain is determined by the argument of the electron-hole off-diagonal exchange integrals. The theory agrees well with the empirical pseudopotential calculations.
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Interaction between Metal Cation and Unnatural Peptide Backbone Mediated by Polarized Water Molecules: Study of Infrared Spectroscopy and Computations.
J Phys Chem B
PUBLISHED: 10-15-2014
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In this work, the interaction between metal cation and a model ?-peptide N-ethylpropionamide (NEPA) in aqueous solution is investigated using infrared absorption spectroscopy. Monovalent (Na(+)), divalent (Ca(2+), Mg(2+)), and trivalent (Al(3+)) metal cations added to NEPA/water solution at moderate concentrations split the amide-I frequency into a red- and blue-shifted component. Molecular dynamics simulations of NEPA in moderate cationic strength are conducted to gain insight into the structural details of the peptide-salt-water system, particularly in the vicinity of the amide group. Our results do not suggest a direct contact between cation and amide oxygen in the solution phase; otherwise, only a significant red shift in the amide-I frequency would occur due to the vibrational Stark effect, as evidenced by quantum chemistry computations. Instead, our results suggest it is the dynamical interaction between the formed cation/water/anion complexes and the amide group that causes the observed split in the amide-I peak, which indicates the presence of both salting-in (red-shifted) and salting-out (blue-shifted) NEPA species. The presence of dynamic and polarized water molecules between the amide oxygen and the cation complex is believed to be the key to the split amide-I peaks in the cation-rich environment. Our results can be useful to better understand the cationic Hofmeister series.
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Photoisomerization and structural dynamics of two nitrosylruthenium complexes: a joint study by NMR and nonlinear IR spectroscopies.
Phys Chem Chem Phys
PUBLISHED: 10-06-2014
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In this work, the photoisomerization and structural dynamics of two isomeric nitrosylruthenium(ii) complexes [Ru(OAc)(2cqn)2NO] (H2cqn = 2-chloro-8-quinolinol) in CDCl3 and DMSO are examined using NMR and IR spectroscopic methods. The two N atoms in the 2cqn ligand are in trans position in the synthesized cis-1 isomer, while they are in cis position in the cis-2 isomer. Kinetics monitored by NMR spectroscopy shows that the rate constant of photoisomerization from cis-2 to cis-1 isomer depends on the wavelength of irradiation and solvent polarity; it proceeds faster on irradiating near the absorption peak in the UV-Vis region, and also in more polar solvents (DMSO). Density functional theory computation indicates that the peculiarity of [Ru(ii)-NO(+)] group affects the structure and reactivity of the nitrosylruthenium complexes. Using the nitrosyl stretching (?NO) to be vibrational probe, the structural dynamics and structural distributions of the cis-1 and cis-2 isomers are examined by steady-state linear infrared and ultrafast two-dimensional infrared (2D IR) spectroscopies. The structural and photochemical aspects of the observed spectroscopic parameters are discussed in terms of solute-solvent interactions for the two nitrosylruthenium complexes.
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Bio-NCs - the marriage of ultrasmall metal nanoclusters with biomolecules.
Nanoscale
PUBLISHED: 10-01-2014
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Ultrasmall metal nanoclusters (NCs) have attracted increasing attention due to their fascinating physicochemical properties. Today, functional metal NCs are finding growing acceptance in biomedical applications. To achieve a better performance in biomedical applications, metal NCs can be interfaced with biomolecules, such as proteins, peptides, and DNA, to form a new class of biomolecule-NC composites (or bio-NCs in short), which typically show synergistic or novel physicochemical and physiological properties. This feature article focuses on the recent studies emerging at the interface of metal NCs and biomolecules, where the interactions could impart unique physicochemical properties to the metal NCs, as well as mutually regulate biological functions of the bio-NCs. In this article, we first provide a broad overview of key concepts and developments in the novel biomolecule-directed synthesis of metal NCs. A special focus is placed on the key roles of biomolecules in metal NC synthesis. In the second part, we describe how the encapsulated metal NCs affect the structure and function of biomolecules. Followed by that, we discuss several unique synergistic effects observed in the bio-NCs, and illustrate them with examples highlighting their potential biomedical applications. Continued interdisciplinary efforts are required to build up in-depth knowledge about the interfacial chemistry and biology of bio-NCs, which could further pave their ways toward biomedical applications.
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Knockout of MIMP protein in lactobacillus plantarum lost its regulation of intestinal permeability on NCM460 epithelial cells through the zonulin pathway.
BMC Gastroenterol
PUBLISHED: 09-29-2014
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Previous studies indicated that the micro integral membrane protein located within the media place of the integral membrane protein of Lactobacillus plantarum CGMCC 1258 had protective effects against the intestinal epithelial injury. In our study, we mean to establish micro integral membrane protein -knockout Lactobacillus plantarum (LPKM) to investigate the change of its protective effects and verify the role of micro integral membrane protein on protection of normal intestinal barrier function.
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Protein-based fluorescent metal nanoclusters for small molecular drug screening.
Chem. Commun. (Camb.)
PUBLISHED: 09-26-2014
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A facile drug screening method based on synthesis of fluorescent gold nanoclusters inside albumin proteins loaded with small molecular drugs and comparing the relative fluorescence intensities of the resultant gold nanoclusters has been developed and successfully applied for the quantitative measurement of drug-protein binding constants.
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Invasive reaction assisted strand-displacement signal amplification for sensitive DNA detection.
Chem. Commun. (Camb.)
PUBLISHED: 09-25-2014
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A novel DNA detection assay was proposed by invasive reaction coupled with molecular beacon assisted strand-displacement signal amplification (IRASA). Target DNAs are firstly hybridized to two probes to initiate invasive reaction to produce amplified flaps. Then these flaps are further amplified by strand-displacement signal amplification. The detection limit was around 0.2 pM.
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Epigenetic Inactivation and Tumor Suppressor Behavior of NGFR in Human Colorectal Cancer.
Mol. Cancer Res.
PUBLISHED: 09-24-2014
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The nerve growth factor receptor (NGFR/p75) is a potential tumor suppressor, but its role in colorectal cancer (CRC) is unknown. Here, the hypermethylation status, biological function, and clinical relevance were determined for p75NGFR in CRC. The methylation status and expression of p75NGFR were assessed in CRC cell lines and clinical tissues by bisulfate genomic sequencing (BGS), qRT-PCR and immunoblot assay. Methylation of p75NGFR was frequently found in CRC, leading to its silencing or down-regulation, and it was effectively restored by a demethylation agent. The overexpression of p75NGFR in multiple CRC cell model systems significantly inhibited cell proliferation (concomitant with G1-phase arrest), invasion, and colony formation and induced cell apoptosis. In contrast, p75NGFR knockdown significantly promoted proliferative and invasive phenotypes. Importantly, p75NGFR methylation was observed in the majority of primary CRC specimens and was associated with histological grade and preoperative serum CA19-9 levels. Multivariate analysis indicated that patients who lack p75NGFR have reduced overall survival (OS; 64% vs. 75%, p=0.028) and disease-free survival (DFS; 61% vs. 72%, p=0.034) compared with p75NGFR-positive patients. In conclusion, p75NGFR is predominantly silenced or down-regulated in CRC, and its biological activities are consistent with it being a relevant tumor suppressor. Implications: p75NGFR is a candidate tumor suppressor and has independent prognostic potential in CRC.
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Two novel zeolitic imidazolate frameworks (ZIFs) as sorbents for solid-phase extraction (SPE) of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples.
Analyst
PUBLISHED: 09-12-2014
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In this work, two novel zeolitic imidazolate framework (ZIF) materials, ZIF-7 and ZIF-11, were firstly introduced as solid-phase extraction (SPE) sorbents for PAHs efficient extraction and highly sensitive analysis in environmental water samples with high performance liquid chromatography (HPLC) coupled with fluorescence detection. ZIF-7 and ZIF-11 were successfully synthesized and characterized with SEM, FTIR, XRD and water contact angels, exhibiting unique and excellent stability, spatial structure and chemical composition, promising for environmental PAHs efficient enrichment through hydrophobic, ?-? and ?-complexation interactions. The topology effect on PAHs extraction was compared between ZIF-7 and ZIF-11, considering they have the same composition in metal ion (Zn(2+)) and organic linker, but differing spatial structures: ZIF-7 has a cubic structure, while ZIF-11 is a rhombic dodecahedron. At last, ZIF-11 with markedly better extraction efficiencies was selected for subsequent analysis. Under optimum extraction conditions such as sample volume, extraction time, desorption conditions, volume of organic modifier and salt concentration, a robust and highly efficient method based on ZIF-11 as a novel SPE sorbent has been successfully developed for environmental PAHs analysis. Satisfactory precision and accuracy ranging from 1-2.4 × 10(3) ng L(-1) as well as ultrasensitive detection limits of 0.08-1.6 ng L(-1) have been successfully achieved. Moreover, ZIF-11 extraction also exhibited high recoveries of 82.4-112.7% with relative standard deviations (RSDs) being less than 9% for PAHs in the environmental water samples. Therefore, our novel, convenient and efficient extraction method based on ZIF-11 as a sorbent is promising for applications in future trace-level environmental PAHs analyses.
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No advantages of laparoscopy for left-sided malignant colonic obstruction compared with open colorectal resection in both short-term and long-term outcomes.
Med. Oncol.
PUBLISHED: 09-04-2014
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Left-sided malignant colonic obstruction is one of the most difficult clinical problems; however, no studies compared the two most common used surgical approach laparoscopic and open colorectomy till now. The purpose of this study was to investigate the short- and long-term outcomes of laparoscopy and open colorectomy for left-sided malignant colonic obstruction. A total of 193 colorectal carcinoma patients (55 patients who underwent laparoscopic colorectomy and 138 who underwent open colorectomy) with left-sided colonic obstruction and surgical therapy, between May 2007 and March 2012, are included in the study. The short-term and long-term outcomes including curative resection rate, hospital stay time, complications, 1-, 3- and 5-year survival rates and recurrence rate, as well as recurrence-free survival rate were analyzed retrospectively. No significant difference was found between the laparoscopic and open groups about the short-term outcomes, such as the curative resection rate (81.82 vs. 78.99%, P=0.658), hospital stay time (24.22±17.09 vs. 24.19±14.76 day, P=0.990), the overall and respective complications (32.73 vs. 39.63%, P=0.674). Long-term outcomes, including 1-, 3- and 5-year survival rates (P=0.518), recurrence rates (P=0.320), and recurrence-free survival rates (P=0.988), were also indicated no significant differences between the two patient groups. Laparoscopy might not have advantages on left-sided malignant colonic obstruction compared with open colorectal resection in both short-term and long-term outcomes.
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Crucial components of mycobacterium type II fatty acid biosynthesis (Fas-II) and their inhibitors.
FEMS Microbiol. Lett.
PUBLISHED: 09-02-2014
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Abundant mycolic acids are the hallmark of the mycobacterial cell wall. The biosynthesis of mycolic acids fulfilled by type I (Fas-I) and type II (Fas-II) synthase systems necessitates long chain fatty acids as the raw material. Fas-I is responsible for de novo fatty acid synthesis to form fatty acids 16-24 carbons in length and then elongated by the monofunctional enzymes of Fas-II to form long chain fatty acids, and further to form mycolic acids. Mutation of monofunctional enzymes can confer mycobacterial drug resistance. The key monofunctional enzymes of this system might represent new drug target candidates for antituberculosis drug development.
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Counterion-Assisted Shaping of Nanocluster Supracrystals.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 08-29-2014
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Ag44 (p-MBA)30 (4-) (p-MBA=para-mercaptobenzoic acid) nanocluster (NC) supracrystals (SCs) with customizable shapes can be obtained by simply altering the type and concentration of the counterions of the p-MBA ligands in the dimethylsulfoxide (DMSO)/water crystallization system. Changing the counterion of the p-MBA ligand from H(+) to Cs(+) eliminates the directional hydrogen bonds in the SCs, resulting in the packing of deprotonated Ag44 (p-MBA)30 (4-) NCs into octahedral SCs, which is in stark contrast to the rhombohedral SCs that were formed by the packing of protonated Ag44 (p-MBA)30 (4-) NCs in previous studies. Furthermore, the double layer of deprotonated Ag44 (p-MBA)30 (4-) NCs is sensitive to charge screening induced by increasing the Cs(+) concentration, thereby providing a means to regulate the precipitation kinetics of the Ag44 (p-MBA)30 (4-) NCs for SC shape engineering. Slow precipitation kinetics was found to favor over-growth at the corners and edges of the octahedral SC nuclei, shaping the SCs into concave octahedra.
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[Undergraduate teaching in life science exemplified by mycobacteriophages].
Yi Chuan
PUBLISHED: 08-22-2014
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An emerging theme of current biomedical study is a synthesis of multi-disciplinary tools to address the complex biological issues. This trend raised the bar for undergraduate teaching and learning. The phage is an ideal material for teaching reform. Inspired by the "phage hunter" project initiated by Pittsburgh University, we present our practice in translating the mycobacteriophage research achievements into undergraduate teaching experience during the last five years.
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Levels of human replication factor C4, a clamp loader, correlate with tumor progression and predict the prognosis for colorectal cancer.
J Transl Med
PUBLISHED: 08-16-2014
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BackgroundHuman replication factor C4 (RFC4) is involved in DNA replication as a clamp loader and is aberrantly regulated across a range of cancers. The current study aimed to investigate the function of RFC4 in colorectal cancer (CRC).MethodsThe mRNA levels of RFC4 were assessed in 30 paired primary CRC tissues and matched normal colonic tissues by quantitative PCR. The protein expression levels of RFC4 were evaluated by western blotting (n =16) and immunohistochemistry (IHC; n =49), respectively. Clinicopathological features and survival data were correlated with the expression of RFC4 by IHC analysis in a tissue microarray comprising 331 surgically resected CRC. The impact of RFC4 on cell proliferation and the cell cycle was assessed using CRC cell lines.Results RFC4 expression was significantly increased in CRC specimens as compared to adjacent normal colonic tissues (P <0.05). High levels of RFC4, determined on a tissue microarray, were significantly associated with differentiation, an advanced stage by the Tumor-Node-Metastasis (TNM) staging system, and a poor prognosis, as compared to low levels of expression (P <0.05). However, in multivariate analysis, RFC4 was not an independent predictor of poor survival for CRC. In vitro studies, the loss of RFC4 suppressed CRC cell proliferation and induced S-phase cell cycle arrest.Conclusion RFC4 is frequently overexpressed in CRC, and is associated with tumor progression and worse survival outcome. This might be attributed to the regulation of CRC cell proliferation and cell cycle arrest by RFC4.
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High expression of Beclin-1 predicts favorable prognosis for patients with colorectal cancer.
Clin Res Hepatol Gastroenterol
PUBLISHED: 08-14-2014
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Beclin-1 is an autophagy gene. It promotes the formation of the autophagic vesicle as well as plays an essential role in guarding the cells against chromosomal instability. Overexpression of Beclin-1 has been reported to predict a favorable survival in various cancers. However, little is known about its prognostic significance in colorectal cancer.
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Serotype-converting bacteriophage SfII encodes an acyltransferase protein that mediates 6-O-acetylation of GlcNAc in Shigella flexneri O-antigens, conferring on the host a novel O-antigen epitope.
J. Bacteriol.
PUBLISHED: 08-11-2014
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Shigella flexneri O-antigen is an important and highly variable cell component presented on the outer leaflet of the outer membrane. Most Shigella flexneri bacteria share an O-antigen backbone composed of ?2)-?-L-Rhap(III)-(1?2)-?-L-Rhap(II)-(1?3)-?-L-Rhap(I)-(1?3)-?-D-GlcpNAc-(1? repeats, which can be modified by adding various chemical groups to different sugars, giving rise to diverse O-antigen structures and, correspondingly, to various serotypes. The known modifications include glucosylation on various sugar residues, O-acetylation on Rha(I) or/and Rha(III), and phosphorylation with phosphoethanolamine on Rha(II) or/and Rha(III). Recently, a new O-antigen modification, namely, O-acetylation at position 6 of N-acetylglucosamine (GlcNAc), has been identified in S. flexneri serotypes 2a, 3a, Y, and Yv. In this study, the genetic basis of the 6-O-acetylation of GlcNAc in S. flexneri was elucidated. An O-acyltransferase gene designated oacD was found to be responsible for this modification. The oacD gene is carried on serotype-converting bacteriophage SfII, which is integrated into the host chromosome by lysogeny to form a prophage responsible for the evolvement of serotype 2 of S. flexneri. The OacD-mediated 6-O-acetylation also occurs in some other S. flexneri serotypes that carry a cryptic SfII prophage with a dysfunctional gtr locus for type II glucosylation. The 6-O-acetylation on GlcNAc confers to the host a novel O-antigen epitope, provisionally named O-factor 10. These findings enhance our understanding of the mechanisms of the O-antigen variation and enable further studies to understand the contribution of the O-acetylation to the antigenicity and pathogenicity of S. flexneri.
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Cerebral ischemia increases bone marrow CD4(+)CD25(+)FoxP3(+) regulatory T cells in mice via signals from sympathetic nervous system.
Brain Behav. Immun.
PUBLISHED: 08-07-2014
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Recent evidence has shown that an increase in CD4(+)CD25(+)FoxP3(+) regulatory T (Treg) cells may contribute to stroke-induced immunosuppression. However, the molecular mechanisms that underlie this increase in Treg cells remain unclear. Here, we used a transient middle cerebral artery occlusion model in mice and specific pathway inhibitors to demonstrate that stroke activates the sympathetic nervous system, which was abolished by 6-OHDA. The consequent activation of ?2-adrenergic receptor (AR) signaling increased prostaglandin E2 (PGE2) level in bone marrow. ?2-AR antagonist prevented the upregulation of PGE2. PGE2, which acts on prostaglandin E receptor subtype 4 (EP4), upregulated the expression of receptor activator for NF-?B ligand (RANKL) in CD4(+) T cells and mediated the increase in Treg cells in bone marrow. Treatment of MCAO mice with RANKL antagonist OPG inhibited the increase in percent of bone marrow Treg cells. PGE2 also elevated the expression of indoleamine 2,3 dioxygenase in CD11C(+) dendritic cells and promoted the development of functional Treg cells. The effect was neutralized by treatment with indomethacin. Concurrently, stroke reduced production of stromal cell-derived factor-1 (SDF-1) via ?3-AR signals in bone marrow but increased the expression of C-X-C chemokine receptor (CXCR) 4 in Treg and other bone marrow cells. Treatment of MCAO mice with ?3-AR antagonist SR-59230A reduced the percent of Treg cells in peripheral blood after stroke. The disruption of the CXCR4-SDF-1 axis may facilitate mobilization of Treg cells and other CXCR4(+) cells into peripheral blood. This mechanism could account for the increase in Treg cells, hematopoietic stem cells, and progenitor cells in peripheral blood after stroke. We conclude that cerebral ischemia can increase bone marrow CD4(+)CD25(+)FoxP3(+) regulatory T cells via signals from the sympathetic nervous system.
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Recombination in truncated genome sequences of porcine circovirus type 2.
Arch. Virol.
PUBLISHED: 08-05-2014
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Porcine circovirus type 2 (PCV2) is the causal agent of a serious disease found in pigs. Here, we report the first detection of truncated genome sequences of PCV2 strain ZJ-R, with the genomic region encoding part of Rep and Cap with a nonviral insertion. To our knowledge, the genome of ZJ-R represents the first PCV2 DNA with a coding insertion. The PCV2 ZJ-R genome is 694 nucleotides long and has two main open reading frames. The whole genome sequence of ZJ-R may facilitate further study of the origin and evolution of PCV2.
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Expression of A disintegrin and metalloprotease 8 is associated with cell growth and poor survival in colorectal cancer.
BMC Cancer
PUBLISHED: 07-30-2014
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A disintegrin and metalloprotease 8 (ADAM8) has been reported to be associated with various malignancies. However, no studies have examined ADAM8 association in colorectal cancer (CRC). The aim of this study was to investigate the expression and function of ADAM8 in CRC.
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Mycobacterium biofilms: factors involved in development, dispersal, and therapeutic strategies against biofilm-relevant pathogens.
Crit. Rev. Eukaryot. Gene Expr.
PUBLISHED: 07-30-2014
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Many bacteria can develop biofilm (BF), a multicellular structure largely combining bacteria and their extracellular polymeric substances (EPS). The formation of biofilm results in an alternative existence in which microbes ensure their survival in adverse environments. Biofilm-relevant infections are more persistent, resistant to most antibiotics, and more recalcitrant to host immunity. Mycobacterium tuberculosis, the causative agent of tuberculosis, can develop biofilm, though whether M. tuberculosis can form biofilm within tuberculosis patients has yet to be determined. Here, we summarize the factors involved in the development and dispersal of mycobacterial biofilms, as well as underlying regulatory factors and inhibitors against biofilm to deepen our understanding of their development and to elucidate potential novel modes of action for future antibiotics. Key factors in biofilm formation identified as drug targets represent a novel and promising avenue for developing better antibiotics.
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Storage of Gold Nanoclusters in Muscle Leads to their Biphasic in Vivo Clearance.
Small
PUBLISHED: 07-25-2014
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Ultrasmall gold nanoclusters (Au NCs) show great potential in biomedical applications. Long-term biodistribution, retention, toxicity, and pharmacokinetics profiles are pre-requisites in their potential clinical applications. Here, the biodistribution, clearance, and toxicity of one widely used Au NC species-glutathione-protected Au NCs or GSH-Au NCs-are systematically investigated over a relatively long period of 90 days in mice. Most of the Au NCs are cleared at 30 days post injection (p.i.) with a major accumulation in liver and kidney. However, it is surprising that an abnormal increase of the Au amount in the heart, liver, spleen, lung, and testis is observed at 60 and 90 days p.i., indicating that the injected Au NCs form a V-shaped time-dependent distribution profile in various organs. Further investigations reveal that Au NCs are steadily accumulating in the muscle in the first 30 days p.i., and the as-stored Au NCs gradually release into the blood in 30-90 days p.i., which induces a re-distribution and re-accumulation of Au NCs in all blood-rich organs. Further hematology and biochemistry studies show that the re-accumulation of Au NCs still causes some liver toxicity at 30 days p.i. The muscle storage and subsequent release may give rise to the potential accumulation and toxicity risk of functional nanomaterials over long periods of time.
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Toward understanding the growth mechanism: tracing all stable intermediate species from reduction of Au(I)-thiolate complexes to evolution of Au?? nanoclusters.
J. Am. Chem. Soc.
PUBLISHED: 07-21-2014
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Despite 20 years of progress in synthesizing thiolated gold nanoclusters (Au NCs), the knowledge of their growth mechanism still lags behind. Herein the detailed process from reduction of Au(I)-thiolate complex precursors to the eventual evolution of and focusing to the atomically precise Au25 NCs was revealed for the first time by monitoring the time evolution of Au(I) precursor and Au NC intermediate species with ESI-MS. A two-stage, bottom-up formation and growth process was proposed: a fast stage of reduction-growth mechanism, followed by a slow stage of intercluster conversion and focusing. Balanced reactions of formation for each identified NC were suggested, backed by theoretical calculations of the thermodynamic driving force. This work advances one step further toward understanding the mechanism of formation and growth of thiolated Au NCs.
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Learning from nature: introducing an epiphyte-host relationship in the synthesis of alloy nanoparticles by co-reduction methods.
Chem. Commun. (Camb.)
PUBLISHED: 07-16-2014
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This communication reports an epiphytic co-reduction method which can overcome the common tendency of sequential deposition in the synthesis of alloy nanoparticles. In this method the reduction of one of the metals (the epiphyte-metal) is only turned-on and rendered more facile by the in situ generated fresh surfaces of the other metal (the host-metal).
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Cryptococcus inositol utilization modulates the host protective immune response during brain infection.
Cell Commun. Signal
PUBLISHED: 07-03-2014
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Background Cryptococcus neoformans is the most common cause of fungal meningitis among individuals with HIV/AIDS, which is uniformly fatal without proper treatment. The underlying mechanism of disease development in the brain that leads to cryptococcal meningoencephalitis remains incompletely understood. We have previously demonstrated that inositol transporters (ITR) are required for Cryptococcus virulence. The itr1a¿ itr3c¿ double mutant of C. neoformans was attenuated for virulence in a murine model of intra-cerebral infection; demonstrating that Itr1a and Itr3c are required for full virulence during brain infection, despite a similar growth rate between the mutant and wild type strains in the infected brain.ResultsTo understand the immune pathology associated with infection by the itr1a¿ itr3c¿ double mutant, we investigated the molecular correlates of host immune response during mouse brain infection. We used genome-wide transcriptome shotgun sequencing (RNA-Seq) and quantitative real-time PCR (qRT-PCR) methods to examine the host gene expression profile in the infected brain. Our results show that compared to the wild type, infection of mouse brains by the mutant leads to significant activation of cellular networks/pathways associated with host protective immunity. Most of the significantly differentially expressed genes (SDEG) are part of immune cell networks such as tumor necrosis factor-alpha (TNF-¿) and interferon-gamma (IFN-¿) regulon, indicating that infection by the mutant mounts a stronger host immune response compared to the wild type. Interestingly, a significant reduction in glucuronoxylomannan (GXM) secretion was observed in the itr1a¿ itr3c¿ mutant cells, indicating that inositol utilization pathways play a role in capsule production.ConclusionsSince capsule has been shown to impact the host response during Cryptococcus-host interactions, our results suggest that the reduced GXM production may contribute to the increased immune activation in the mutant-infected animals.
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Genetic and structural identification of an O-acyltransferase gene ( oacC ) responsible for the 3/4-O-acetylation on rhamnose III in Shigella flexneri serotype 6.
BMC Microbiol.
PUBLISHED: 06-30-2014
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BackgroundO-antigen (O-polysaccharide) of the lipopolysaccharide is a highly variable cell component of the outer membrane in Shigella flexneri. It defines the serospecificity and plays an important role in the pathogenesis of shigellosis. There are two distinct O-antigen forms for the 19 serotypes of S. flexneri: one for serotypes 1¿5, X, Y, 7 (and their subtypes), and the other for serotype 6. Although having different basal O-polysaccharide structures, the two forms share a common disaccharide fragment [¿2)-¿-l-Rhap III-(1¿¿¿2)-¿-l-Rhap II]. In serotype 6 and some non-6 serotypes, RhaIII is O-acetylated at position either 3 or 4 (3/4-O-acetylation), conferring to the hosts a novel antigenic determinant named O-factor 9. An acyltransferase gene (oacB) responsible for this modification has been identified in serotypes 1a, 1b, 2a, 5a, and Y, but not in serotype 6.ResultsUsing genetic, serological, and chemical approaches, another acyltransferase gene named oacC was demonstrated to be responsible for the 3/4-O-acetylation on RhaIII in the O-antigen of S. flexneri serotype 6. Inactivation of the oacC gene resulted in the loss of the 3/4-O-acetyltion, and the cloned oacC gene restored this modification upon transformation. In accordance with the similarity in the acceptor substrate structure and high sequence homology (72% identity) between oacC and oacB, oacC has the interchangeable function with the oacB gene in mediation of the 3/4-O-acetylation. The oacC gene is located in a prophage on the chromosome and presented in all 77 serotype 6 strains tested.ConclusionsIdentification and functional characterization of the O-acetyltransferase encoding gene, oacC, shows that it is involved in O-antigen modification by 3/4-O-acetylation on RhaIII specific to serotype 6.
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Novel Theranostic DNA Nanoscaffolds for the Simultaneous Detection and Killing of Escherichia coli and Staphylococcus aureus.
ACS Appl Mater Interfaces
PUBLISHED: 06-19-2014
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A novel theranostic platform is made by utilizing a self-assembled DNA nanopyramid (DP) as scaffold for incorporation of both detection and therapeutic moieties to combat bacterial infection. Red-emissive glutathione-protected gold nanoclusters (GSH-Au NCs) were used for bacterial detection. Actinomycin D (AMD) that was intercalated on the DP scaffold was used as therapeutic agent. This results in the formation of theranostic DPAu/AMD. Model bacteria Escherichia coli and Staphylococcus aureus were found to be readily taken in the DPAu/AMD and be susceptible to its killing effect. In addition, DPAu/AMD was observed to outperform the free AMD in killing infectious bacteria. The degradation of the DP structure by DNase was found to be responsible for the release of AMD and the effective killing effect of the infectious bacteria. This novel strategy presents a basic platform for future improvements to detect infectious bacteria and treatment.
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Comparative genomics of Mycobacterium tuberculosis drug efflux pumps and their transcriptional regulators.
Crit. Rev. Eukaryot. Gene Expr.
PUBLISHED: 06-19-2014
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Efflux pump systems are important in general drug resistance. Understanding efflux pumps can inform drug target selection and novel antibiotics designs. In this review, we have summarized the physiological roles, types, and mechanisms of drug efflux pumps. Mycobacterium tuberculosis is the causative agent of tuberculosis, a global threat to public health, and the increasing resistance of this mycobacterium to antibiotics is alarming. Therefore, we have focused on the comparative genomics of efflux pumps and relevant transcriptional regulators of M. tuberculosis.
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Deep sequencing analysis of microRNA expression in porcine serum-induced hepatic fibrosis rats.
Ann Hepatol
PUBLISHED: 06-14-2014
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Recent studies have suggested miRNA dysregulation in liver tissue mediates the pathogenesis of various liver diseases especially liver fibrosis, but the microRNA changes during PS-induced hepatic fibrosis are still unknown. The purpose of this study was to screen the miRNA differences in rat liver fibrosis model and clarify the relationship of miRNAs with the development of PS-induced liver fibrosis.
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Partial hepatectomy for liver metastases from nasopharyngeal carcinoma: a comparative study and review of the literature.
BMC Cancer
PUBLISHED: 06-13-2014
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The management of liver metastases from nasopharyngeal carcinoma (NPC) has not been extensively investigated. This study aimed to compare the long-term outcome of patients with liver metastases from NPC who were treated by a partial hepatectomy or transcatheter hepatic artery chemoembolization (TACE).
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Facile synthesis of water-soluble Au(25-x)Ag(x) nanoclusters protected by mono- and bi-thiolate ligands.
Chem. Commun. (Camb.)
PUBLISHED: 05-31-2014
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A series of water-soluble Au25-xAgx nanoclusters (NCs) protected by mono- and bi-thiolate ligands are synthesized via the NaOH-mediated NaBH4 reduction method. Compositions of both the metal core and the ligand shell can be tailored by varying the feeding ratios of metal precursors and hetero-ligands, further enriching the functionalities of the NCs.
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Characterization of a tuberculosis patient's sera reactive Mycobacterium tuberculosis transcription factor Rv2175c.
J Immunoassay Immunochem
PUBLISHED: 05-28-2014
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The transcriptional factor plays an important role in the regulation of gene expression and crucial to understand the biology of organisms. Mycobacterium tuberculosis, the causative agent of tuberculosis, harbors multiple transcriptional factors. Few transcriptional factors are well-documented antigens. Based on the screening of antigen with TB patients sera, a functional unknown ORF (Rv2175c) annotated as transcriptional factor was heterologously expressed, purified and for serodiagnostic value. E.coli recombinant Rv2175c protein was produced and antibodies were generated in rabbit using the recombinant antigens. ELISA and novel electrochemical immunosensor were employed in a parallel fashion in order to define its serodiagnositic value. Electrochemical immunosensor showed a sharp difference between health and TB sera. The data showed that Rv2715c is antigenic and can be used for TB seradignosis candidate in non BCG vaccinated areas.
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?-conjugated carbon radicals at graphene oxide to initiate ultrastrong chemiluminescence.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 05-15-2014
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Graphene oxide has widely been employed in various fields, but its structure and composition has still not been fully understood. Here we report that freshly prepared graphene oxide exhibits a large number of ?-conjugated carbon radicals at its ?-network plane, which result from the addition reaction of hydroxyl radicals from H2O2 onto the conjugated double bonds of graphene oxide. The ?-conjugated carbon radicals can directly initiate the long-lasting visible chemiluminescence of luminol, which is even stronger than that obtained when horseradish peroxidase and H2O2 are used. Previously, graphene oxide was mainly reported to be a quencher of chemiluminescence instead. Remarkably, the reacted radicals can be regenerated, thereby enabling the repetitive initiation of chemiluminescence by re-treatment of graphene oxide. The results reported here provide a new understanding of the structure, properties, and applications of graphene oxide.
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Double-balloon catheter vs. dinoprostone vaginal insert for induction of labor with an unfavorable cervix.
Arch. Gynecol. Obstet.
PUBLISHED: 05-07-2014
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To compare a double-balloon catheter and dinoprostone vaginal insert for induction of labor with an unfavorable cervix.
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Molecular basis underlying Mycobacterium tuberculosis D-cycloserine resistance. Is there a role for ubiquinone and meraquinone metabolic pathways?
Expert Opin. Ther. Targets
PUBLISHED: 04-29-2014
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Tuberculosis remains a formidable threat to global public health. Multidrug-resistant tuberculosis presents increasing burden on the control strategy. D-Cycloserine (DCS) is an effective second-line drug against Mycobacterium tuberculosis (M. tuberculosis), the causative agent of tuberculosis. Though less potent than isoniazid (INH) and streptomycin, DCS is crucial for antibiotic-resistant tuberculosis. One advantage of DCS is that less drug-resistant M. tuberculosis is reported in comparison with first-line antituberculosis drugs such as INH and rifampin.
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Refluxing synthesis, photoluminescence and binding ability to deoxyribonucleic acid of water-soluble rare earth ion-doped LaF3 nanoparticles.
J Nanosci Nanotechnol
PUBLISHED: 04-18-2014
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Water-soluble rare earth ion (Ce3+, Tb3+)-doped LaF3 nanoparticles with the ability to bind to deoxyribonucleic acid (DNA) were prepared by the refluxing method in a glycerol/water mixture and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and so on. The obtained LaF3:Ce3+, LaF3:Tb3+ and LaF3:Ce3+, Tb3+ nanoparticles are well crystallized with a hexagonal structure and composed of spherical particles with an average size from 11 to 19 nm. The as-prepared samples can be dispersed into water to form a colloidal solution. Under ultraviolet (UV) light irradiation, the emission lines of Tb3+ in the co-doped LaF3:Ce3+, Tb3+ are evidently strengthened compared to those in the single-doped LaF3:Tb3+ nanoparticles, which is due to the energy transfer from Ce3+ to Tb3+ ions in the LaF3:Ce3+, Tb3+ samples. The biological experiment confirms that the water-soluble LaF3:Ce3+, Tb3+ nanoparticles can be bonded to the DNA molecules and emit visible light under UV irradiation. These luminescent nanoparticles could be used similarly to ethidium bromide (EtBr), which has been used extensively as a DNA staining reagent. The advantage that LaF3:Ce3+, Tb3+ nanoparticles have lower toxicity than EtBr makes them a potential reagent instead of EtBr in the DNA staining in biological experiments.
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Phased surgical treatment of barium enema-induced rectal injury and retention of barium in the pelvic floor space.
Ann Transl Med
PUBLISHED: 04-10-2014
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Iatrogenic injuries caused by barium enema are rarely reported. Following a phased surgical protocol for up to one year, we have successfully treated a patient with rectal injury and severe infection of the pelvic floor space complicated with retention of large amounts of barium and vaginal fistula. In this article, the phased surgery planning for the treatment of rectal injury complicated with vaginal fistula is discussed in terms of the pros and cons, and the observed effect and evolution of barium retained in the pelvic floor space are described.
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Convenient purification of gold clusters by co-precipitation for improved sensing of hydrogen peroxide, mercury ions and pesticides.
Chem. Commun. (Camb.)
PUBLISHED: 04-10-2014
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An effective separation process is developed to remove free protein from the protein-protected gold clusters via co-precipitation with zinc hydroxide on their surface. After dialysis, the purified clusters exhibit an enhanced fluorescence for improved sensitive detection and selective visualization.
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Dietary manganese supplementation influences the expression of transporters involved in iron metabolism in chickens.
Biol Trace Elem Res
PUBLISHED: 04-01-2014
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To investigate the effects of dietary manganese (Mn) supplementation on iron (Fe) metabolism, a total of 480 50-week-old hens were fed the basal diet (control, 24.35 mg Mn/kg) without Mn supplementation for 6 weeks to reduce Mn storage in the body. Hens were then randomly assigned to one of three treatments, which included the control and control added with 60 or 300 mg Mn/kg diet (M-Mn or H-Mn). Duodenum, heart, liver, and tibia were collected in hens after 12-week feeding period. No significant differences were observed in egg production, feed/egg ratio, shell breaking strength, and shell thickness among different treatments. Compared with control or M-Mn, H-Mn decreased (P??0.10) Fe concentration in the heart and tibia. In conjunction with reduced Fe retention, DMT1 mRNA expression decreased (P?
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Mycobacterium tuberculosis serine protease Rv3668c can manipulate the host-pathogen interaction via Erk-NF-?B axis-mediated cytokine differential expression.
J. Interferon Cytokine Res.
PUBLISHED: 03-31-2014
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Tuberculosis caused by Mycobacterium tuberculosis (MTB) remains a serious global public health concern. About one-third of the global population has been latently infected with this pathogen. MTB proteases are important virulence factors and involve in subverting the host immunity. MTB protease Rv3668c was implicated in drug action and dormancy by Gene Expression Omnibus data. To define the role of Rv3668c in pathogen-host interaction, we constructed recombinant strain Mycobacterium smegmatis-Rv3668c (Ms-Rv3668c). The resultant strains were used to challenge the human macrophage cell line U937. The cytokine levels and the survival of recombinants and macrophages were monitored. The results showed that recombinant Ms-Rv3668c specifically upregulated the secretion of proinflammatory cytokines TNF-?, IL-1?, and IL-6 and downregulated the secretion of anti-inflammatory cytokine IL-10 by U937 cells, consistent with the upregulated transcription of TNF-? and IL-1?. Rv3668c recombinants demonstrated prolonged survival within the U937 cells and accelerated the death of the host cells. Inhibitor experiments showed that the ERK-NF-?B axis was involved in the Rv3668c-triggered TNF-? and IL-1? changes. These results provided evidence for the engagement of Rv3668c in the interaction between Mycobacterium and host.
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The cooperative behaviour of antimicrobial peptides in model membranes.
Biochim. Biophys. Acta
PUBLISHED: 03-28-2014
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A systematic analysis of the hypothesis of the antimicrobial peptides' (AMPs) cooperative action is performed by means of full atomistic molecular dynamics simulations accompanied by circular dichroism experiments. Several AMPs from the aurein family (2.5,2.6, 3.1), have a similar sequence in the first ten amino acids, are investigated in different environments including aqueous solution, trifluoroethanol (TFE), palmitoyloleoylphosphatidylethanolamine (POPE), and palmitoyloleoylphosphatidylglycerol (POPG) lipid bilayers. It is found that the cooperative effect is stronger in aqueous solution and weaker in TFE. Moreover, in the presence of membranes, the cooperative effect plays an important role in the peptide/lipid bilayer interaction. The action of AMPs is a competition of the hydrophobic interactions between the side chains of the peptides and the hydrophobic region of lipid molecules, as well as the intra peptide interaction. The aureins 2.5-COOH and 2.6-COOH form a hydrophobic aggregate to minimize the interaction between the hydrophobic group and the water. Once that the peptides reach the water/lipid interface the hydrophobic aggregate becomes smaller and the peptides start to penetrate into the membrane. In contrast, aurein 3.1-COOH forms only a transient aggregate which disintegrates once the peptides reached the membrane, and it shows no cooperativity in membrane penetration.
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The influence of lysosomal stability of silver nanomaterials on their toxicity to human cells.
Biomaterials
PUBLISHED: 03-27-2014
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How silver nanomaterials (Ag NMs) could induce toxicity has been debated heatedly by many researchers. We utilized Ag nanoclusters (Ag NCs) with the same size and ligand protection but different core surface speciation. Ag(+)-rich NCs (Ag(+)-R NCs) and their counterpart, the reduced Ag(0)-rich NCs (Ag(0)-R NCs) are synthesized to represent possible dichotomous stages in silver nanomaterial degradation process. Here we show Ag(0)-R NCs induce higher cellular toxicity when compared to Ag(+)-R NCs. This cellular toxicity is brought about via the modulation of reactive oxygen species (ROS) in cells as a result of the more rapid release of Ag species from Ag(0)-R NCs and subsequent oxidation into Ag(+) in the lysosomal compartment. The weaker Ag(0)-R bond greatly potentiated the release of Ag species in the acidic and enzymatic processes within the lysosomes. Since lysosomes are absent in bacteria, increasing silver nanomaterials stability may lower toxicity in mammalian cells whilst not reducing their efficacy to fight bacteria; this redesign can result in a safer silver nanomaterial.
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Prophage-like elements present in Mycobacterium genomes.
BMC Genomics
PUBLISHED: 03-24-2014
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Prophages, integral components of many bacterial genomes, play significant roles in cognate host bacteria, such as virulence, toxin biosynthesis and secretion, fitness cost, genomic variations, and evolution. Many prophages and prophage-like elements present in sequenced bacterial genomes, such as Bifidobacteria, Lactococcus and Streptococcus, have been described. However, information for the prophage of Mycobacterium remains poorly defined.
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Balancing the rate of cluster growth and etching for gram-scale synthesis of thiolate-protected Au(25) nanoclusters with atomic precision.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 03-24-2014
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We report a NaOH-mediated NaBH4 reduction method for the synthesis of mono-, bi-, and tri-thiolate-protected Au25 nanoclusters (NCs) with precise control of both the Au core and thiolate ligand surface. The key strategy is to use NaOH to tune the formation kinetics of Au NCs, i.e., reduce the reduction ability of NaBH4 and accelerate the etching ability of free thiolate ligands, leading to a well-balanced reversible reaction for rapid formation of thermodynamically favorable Au25 NCs. This protocol is facile, rapid (?3?h), versatile (applicable for various thiolate ligands), and highly scalable (>1?g Au NCs). In addition, bi- and tri-thiolate-protected Au25 NCs with adjustable ratios of hetero-thiolate ligands were easily obtained. Such ligand precision in molecular ratios, spatial distribution and uniformity resulted in richly diverse surface landscapes on the Au NCs consisting of multiple functional groups such as carboxyl, amine, and hydroxy. Analysis based on NMR spectroscopy revealed that the hetero-ligands on the NCs are well distributed with no ligand segregation. The unprecedented synthesis of multi-thiolate-protected Au25 NCs may further promote the practical applications of functional metal NCs.
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Determination of urinary aromatic amines in smokers and nonsmokers using a MIPs-SPE coupled with LC-MS/MS method.
J. Chromatogr. B Analyt. Technol. Biomed. Life Sci.
PUBLISHED: 03-19-2014
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Urinary aromatic amines (AAs) could be used as biomarkers for human exposure to AAs in cigarette smoke. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of urinary AAs (i.e. 1-naphthylamine (1-NA), 2-naphthylamine (2-NA), 3-aminobiphenyl (3-ABP) and 4-aminobiphenyl (4-ABP)) in smokers and nonsmokers. A molecularly imprinted polymers (MIPs) solid phase extraction (SPE) cartridge was applied to purify urine samples and no derivatization reaction was involved. Each analytes used respective stable isotope internal standards, which could well compensate matrix effect. Lower limit of detections (LODs) for four AAs were obtained and in the range of 1.5-5ngL(-1). Recovery ranged from 87.7±4.5% to 111.3±6.4% and precision were less than 9.9%. The method was applied to analyze urine samples of 40 smokers and 10 nonsmokers. The 24h urinary excretion amounts of total AAs were higher for smokers compared with nonsmokers. What's more, 1-NA, 3-ABP and 4-ABP excretion amounts showed significant differences (p<0.05) between smokers and nonsmokers.
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The roles of bacterial GCN5-related N-acetyltransferases.
Crit. Rev. Eukaryot. Gene Expr.
PUBLISHED: 03-04-2014
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The GCN5-related N-acetyltransferase (GNAT) superfamily of proteins, widespread in eukaryotes and prokaryotes, can utilize acyl coenzyme A (acyl CoA) to acylate respective acceptor substrates and release both CoA and the acylated products. GNATs have been shown to be involved in multiple physiological events, including bacterial drug resistance, regulation of transcription, stress reaction, and metabolic flux, etc. In the last few years, the importance of GNATs has only emerged in eukaryotes, but bacterial GNATs, particularly those of pathogens, have only recently been explored. In this review, we summarize the main members, structures, inhibitors, and activators of proteins in the GNAT family. We focus on the roles of GNATs in bacteria, particularly Mycobacterium tuberculosis GNATs.
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Ultrasmall Au(10-12)(SG)(10-12) nanomolecules for high tumor specificity and cancer radiotherapy.
Adv. Mater. Weinheim
PUBLISHED: 02-24-2014
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Radiosensitizers can increase local treatment efficacy under a relatively low and safe radiation dose, thereby facilitating tumor eradication and minimizing side effects. Here, a new class of radiosensitizers is reported, which contain several gold (Au) atoms embedded inside a peptide shell (e.g., Au10-12 (SG)10-12 ) and can achieve ultrahigh tumor uptake (10.86 SUV at 24 h post injection) and targeting specificity, efficient renal clearance, and high radiotherapy enhancement.
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Navigating through the maze of TLR2 mediated signaling network for better mycobacterium infection control.
Biochimie
PUBLISHED: 02-21-2014
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Toll-like receptor 2 (TLR2), a member of pattern recognition receptors (PRRs) abundant on macrophages, dendritic cells (DCs) and respiratory epithelial cells lining the lung, plays critical role in host immune response against Mycobacterium tuberculosis (MTB) infection. TLR2-mediated elimination of MTB involves multiple pathways such as promoting DCs maturation, generating biased Th1, Th2, Th17 type response, regulating the macrophage activation and cytokine secretion. MTB can also hijack the TLR2 signaling to subvert the host immunity by dampening the macrophages response to IFN-?, suppressing the processing and presentation of antigens. This review summarizes the intricate network of TLR2-mediated signaling and Mycobacteria effectors involved in MTB-host interaction with an aim to find better target for improved tuberculosis control, especially the host-derived therapy targets. TLR2 agonists with potential to be included in novel tuberculosis vaccines are also discussed.
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Toxicity profiling of water contextual zinc oxide, silver, and titanium dioxide nanoparticles in human oral and gastrointestinal cell systems.
Environ. Toxicol.
PUBLISHED: 02-13-2014
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Engineered nanoparticles (ENPs) are increasingly detected in water supply due to environmental release of ENPs as the by-products contained within the effluent of domestic and industrial run-off. The partial recycling of water laden with ENPs, albeit at ultra-low concentrations, may pose an uncharacterized threat to human health. In this study, we investigated the toxicity of three prevalent ENPs: zinc oxide, silver, and titanium dioxide over a wide range of concentrations that encompasses drinking water-relevant concentrations, to cellular systems representing oral and gastrointestinal tissues. Based on published in silico-predicted water-relevant ENPs concentration range from 100 pg/L to 100 µg/L, we detected no cytotoxicity to all the cellular systems. Significant cytotoxicity due to the NPs set in around 100 mg/L with decreasing extent of toxicity from zinc oxide to silver to titanium dioxide NPs. We also found that noncytotoxic zinc oxide NPs level of 10 mg/L could elevate the intracellular oxidative stress. The threshold concentrations of NPs that induced cytotoxic effect are at least two to five orders of magnitude higher than the permissible concentrations of the respective metals and metal oxides in drinking water. Based on these findings, the current estimated levels of NPs in potable water pose little cytotoxic threat to the human oral and gastrointestinal systems within our experimental boundaries. © 2014 Wiley Periodicals, Inc. Environ Toxicol, 2014.
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Combined targeting of STAT3/NF-?B/COX-2/EP4 for effective management of pancreatic cancer.
Clin. Cancer Res.
PUBLISHED: 02-11-2014
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Near equal rates of incidence and mortality emphasize the need for novel targeted approaches for better management of patients with pancreatic cancer. Inflammatory molecules NF-?B and STAT3 are overexpressed in pancreatic tumors. Inhibition of one protein allows cancer cells to survive using the other. The goal of this study is to determine whether targeting STAT3/NF-?B crosstalk with a natural product Nexrutine can inhibit inflammatory signaling in pancreatic cancer.
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Palmatine inhibits growth and invasion in prostate cancer cell: Potential role for rpS6/NF?B/FLIP.
Mol. Carcinog.
PUBLISHED: 02-03-2014
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Novel agents are desperately needed for improving the quality of life and 5-year survival to more than 30% for metastatic castrate-resistant prostate cancer. Previously we showed that Nexrutine, Phellodendron amurense bark extract, inhibits prostate tumor growth in vitro and in vivo. Subsequently using biochemical fractionation we identified butanol fraction contributes to the observed biological activities. We report here that palmatine, which is present in the butanol fraction, selectively inhibits growth of prostate cancer cells without significant effect on non-tumorigenic prostate epithelial cells. By screening receptor tyrosine kinases in a protein kinase array, we identified ribosomal protein S6, a downstream target of p70S6K and the Akt/mTOR signaling cascade as a potential target. We further show that palmatine treatment is associated with decreased activation of NF?B and its downstream target gene FLIP. These events led to inhibition of invasion. Similar results were obtained using parent extract Nexrutine (Nx) suggesting that palmatine either in the purified form or as one of the components in Nx is a potent cytotoxic agent with tumor invasion inhibitory properties. Synergistic inhibition of rpS6/NF?B/FLIP axis with palmatine may have therapeutic potential for the treatment of prostate cancer and possibly other malignancies with their constitutive activation. These data support a biological link between rpS6/NF?B/FLIP in mediating palmatine-induced inhibitory effects and warrants additional preclinical studies to test its therapeutic efficacy. © 2014 Wiley Periodicals, Inc.
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Mycobacterium tuberculosis PPE family protein Rv1808 manipulates cytokines profile via co-activation of MAPK and NF-?B signaling pathways.
Cell. Physiol. Biochem.
PUBLISHED: 01-31-2014
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Mycobacterium tuberculosis is an extremely successful intracellular pathogen armed with multiple tactics to subvert host immunity. PPE (Pro-Pro-Glu) family exclusively distributed in mycobacteria might be responsible for the virulence and pathogenicity of M.tuberculosis. The up-regulation of Rv1808 (PPE32) in many conditions prompted us to define its role in host innate immune response.
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Unexpected extensive lysine acetylation in the trump-card antibiotic producer Streptomyces roseosporus revealed by proteome-wide profiling.
J Proteomics
PUBLISHED: 01-24-2014
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Lysine acetylation is emerging as a ubiquitous and conserved posttranslational modification in living cells. While the role of lysine acetylation in regulating primary metabolism is well-established, its function in secondary metabolism remains largely elusive. To gain insight into the nature, extent and biological function of lysine acetylation in Streptomyces reseosporus, a producer of daptomycin, dubiously dubbed as the trump card antibiotic, we used immunoaffinity-based acetyllysine peptide enrichment integrated with high resolution mass spectrometry to comprehensively characterize lysine acetylated proteins in this microbe. We identified a total of 667 proteins with 1143 unique sites, representing the largest acetylproteome reported to date in bacteria. Acetylated proteins belong to various functional classes such as metabolism and gene expression according to the gene ontology. We demonstrated for the first time that proteins involved in the biosynthesis of diverse secondary metabolites are acetylated, such as a nonribosomal peptide synthetase, enzymes essential for hydroxamate siderophore and phosphinic acid natural products biosynthesis, implying an important role of acetylation in these processes. Taken together, this proteomic analysis revealed a surprising breadth of cellular processes affected by lysine acetylation and also furnishes some fresh intervention nodes for the rational improvement of the antibiotic producer.
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Characterization of a novel mutation in the overlap of tlyA and ppnK involved in capreomycin resistance in Mycobacterium.
IUBMB Life
PUBLISHED: 01-21-2014
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Capreomycin (CAP) is an important second-line drug for multidrug-resistant tuberculosis. To further define the drug resistance mechanism of CAP, a Mycobacterium smegmatis transposon mutant library was constructed using Tn5 transposon for screening isolates with enhanced CAP resistance. A mutant (named C4) with fourfold increased CAP resistance was isolated and characterized. Tn5 was found to be inserted into MSMEG_0841, an annotated pseudogene. However, knockout demonstrated that MSMEG_0841 was not responsible for CAP resistance. We further sequenced the whole genome of C4 and found an A to G substitution in the overlap region between tlyA and ppnK, which leads a stop codon mutation in upstream tlyA and a T2A mutation in downstream ppnK. Mutation in the overlap might confer the dysfuction of both genes. tlyA is a known gene involved in CAP action. Overexpression of ppnK in both Escherichia coli and M. smegmatis confer subtle susceptible to CAP. Taken together, our study found that a novel mutation involved in CAP resistance.
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Stellated Ag-Pt bimetallic nanoparticles: an effective platform for catalytic activity tuning.
Sci Rep
PUBLISHED: 01-20-2014
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The usefulness of Pt-based nanomaterials for catalysis can be greatly enhanced by coupling morphology engineering to the strategic presence of a second or even third metal. Here we demonstrate the design and preparation of stellated Ag-Pt bimetallic nanoparticles where significant activity difference between the methanol oxidation reaction (MOR) and the oxygen reduction reaction (ORR) may be realized by relegating Ag to the core or by hollowing out the core. In particular the stellated Pt surface, with an abundance of steps, edges, corner atoms, and {111} facets, is highly effective for the ORR but is ineffective for MOR. MOR activity is only observed in the presence of a Ag core through electronic coupling to the stellated Pt shell. The bimetallic Ag-Pt stellates therefore demonstrate the feasibility of tuning a Pt surface for two very different structure sensitive catalytic reactions. Stellated bimetallics may therefore be an effective platform for highly tunable catalyst designs.
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Simultaneous determination of fifteen heterocyclic aromatic amines in the urine of smokers and nonsmokers using ultra-high performance liquid chromatography-tandem mass spectrometry.
J Chromatogr A
PUBLISHED: 01-16-2014
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A sensitive UHPLC-MS/MS method to simultaneously determine fifteen heterocyclic aromatic amines (HAAs) was developed and applied analyze of human urine. The detection limit of the fifteen HAAs was 0.80-6.06 pg/mL and the quantitation limit was 2.65-20.2 pg/mL. The intra-day and inter-day precisions of all HAAs were ?10%. Based on the high sensitivity and good precision, the method was successively applied to analyze the urine of smokers and nonsmokers. Ten HAAs were detected, analyzed and compared between the two groups, and the analytical results showed that cigarette smoke could increase the exposures to 2-amino-9H-pyrido[2,3-b]indole (A?C) and 2-amino-1,6-dimethylimidazo[4,5-b]-pyridine (DMIP). This work is the first report that ten HAAs were simultaneously detected, and is the first comprehensive study of HAA exposure induced by cigarette smoking.
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Identification of a highly luminescent Au22(SG)18 nanocluster.
J. Am. Chem. Soc.
PUBLISHED: 01-14-2014
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The luminescence property of thiolated gold nanoclusters (Au NCs) is thought to involve the Au(I)-thiolate motifs on the NC surface; however, this hypothesis remains largely unexplored because of the lack of precise molecular composition and structural information of highly luminescent Au NCs. Here we report a new red-emitting thiolated Au NC, which has a precise molecular formula of Au22(SR)18 and exhibits intense luminescence. Interestingly, this new Au22(SR)18 species shows distinctively different absorption and emission features from the previously reported Au22(SR)16, Au22(SR)17, and Au25(SR)18. In stark contrast, Au22(SR)18 luminesces intensely at ?665 nm with a high quantum yield of ?8%, while the other three Au NCs show very weak luminescence. Our results indicate that the luminescence of Au22(SR)18 originates from the long Au(I)-thiolate motifs on the NC surface via the aggregation-induced emission pathway. Structure prediction by density functional theory suggests that Au22(SR)18 has two RS-[Au-SR]3 and two RS-[Au-SR]4 motifs, interlocked and capping on a prolate Au8 core. This predicted structure is further verified experimentally by Au L3-edge X-ray absorption fine structure analysis.
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Modelling and analysis on biomechanical dynamic characteristics of knee flexion movement under squatting.
ScientificWorldJournal
PUBLISHED: 01-04-2014
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The model of three-dimensional (3D) geometric knee was built, which included femoral-tibial, patellofemoral articulations and the bone and soft tissues. Dynamic finite element (FE) model of knee was developed to simulate both the kinematics and the internal stresses during knee flexion. The biomechanical experimental system of knee was built to simulate knee squatting using cadaver knees. The flexion motion and dynamic contact characteristics of knee were analyzed, and verified by comparing with the data from in vitro experiment. The results showed that the established dynamic FE models of knee are capable of predicting kinematics and the contact stresses during flexion, and could be an efficient tool for the analysis of total knee replacement (TKR) and knee prosthesis design.
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Assembly of nanoions via electrostatic interactions: ion-like behavior of charged noble metal nanoclusters.
Sci Rep
PUBLISHED: 01-02-2014
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The assembly of ultrasmall metal nanoclusters (NCs) is of interest to both basic and applied research as it facilitates the determination of cluster structures and the customization of cluster physicochemical properties. Here we present a facile and general approach to assemble noble metal NCs by selectively inducing electrostatic interactions between negatively-charged metal NCs and divalent cations. The charged metal NCs, which have well-defined sizes, charges and structures; and behave similarly to multivalent anions, can be considered as nanoions. These nanoions exhibit step-like assembly behavior when interacting with the counter cations - assembly only occurs when the solubility product (Ksp) between the carboxylate ions on the NC surface and the divalent cations is exceeded. The assembly here is distinctively different from the random aggregation of colloidal particles by counter ions. The nanoions would assemble into fractal-like monodisperse spherical particles with a high order of regularity that mimic the assembly of ionic crystals.
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Phage based green chemistry for gold ion reduction and gold retrieval.
ACS Appl Mater Interfaces
PUBLISHED: 01-02-2014
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The gold mining industry has taken its toll on the environment, triggering the development of more environmentally benign processes to alleviate the waste load release. Here, we demonstrate the use of bacteriophages (phages) for biosorption and bioreduction of gold ions from aqueous solution, which potentially can be applied to remediate gold ions from gold mining waste effluent. Phage has shown a remarkably efficient sorption of gold ions with a maximum gold adsorption capacity of 571 mg gold/g dry weight phage. The product of this phage mediated process is gold nanocrystals with the size of 30-630 nm. Biosorption and bioreduction processes are mediated by the ionic and covalent interaction between gold ions and the reducing groups on the phage protein coat. The strategy offers a simple, ecofriendly and feasible option to recover of gold ions to form readily recoverable products of gold nanoparticles within 24 h.
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Promoting Utilization of Saccharum spp. Genetic Resources through Genetic Diversity Analysis and Core Collection Construction.
PLoS ONE
PUBLISHED: 01-01-2014
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Sugarcane (Saccharum spp.) and other members of Saccharum spp. are attractive biofuel feedstocks. One of the two World Collections of Sugarcane and Related Grasses (WCSRG) is in Miami, FL. This WCSRG has 1002 accessions, presumably with valuable alleles for biomass, other important agronomic traits, and stress resistance. However, the WCSRG has not been fully exploited by breeders due to its lack of characterization and unmanageable population. In order to optimize the use of this genetic resource, we aim to 1) genotypically evaluate all the 1002 accessions to understand its genetic diversity and population structure and 2) form a core collection, which captures most of the genetic diversity in the WCSRG. We screened 36 microsatellite markers on 1002 genotypes and recorded 209 alleles. Genetic diversity of the WCSRG ranged from 0 to 0.5 with an average of 0.304. The population structure analysis and principal coordinate analysis revealed three clusters with all S. spontaneum in one cluster, S. officinarum and S. hybrids in the second cluster and mostly non-Saccharum spp. in the third cluster. A core collection of 300 accessions was identified which captured the maximum genetic diversity of the entire WCSRG which can be further exploited for sugarcane and energy cane breeding. Sugarcane and energy cane breeders can effectively utilize this core collection for cultivar improvement. Further, the core collection can provide resources for forming an association panel to evaluate the traits of agronomic and commercial importance.
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Mycobacterium tuberculosis Rv3402c enhances mycobacterial survival within macrophages and modulates the host pro-inflammatory cytokines production via NF-kappa B/ERK/p38 signaling.
PLoS ONE
PUBLISHED: 01-01-2014
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Intracellular survival plays a central role in the pathogenesis of Mycobacterium tuberculosis, a process which depends on an array of virulence factors to colonize and replicate within the host. The M. tuberculosis iron regulated open reading frame (ORF) rv3402c, encoding a conserved hypothetical protein, was shown to be up-regulated upon infection in both human and mice macrophages. To explore the function of this ORF, we heterologously expressed the rv3402c gene in the non-pathogenic fast-growing Mycobacterium smegmatis strain, and demonstrated that Rv3402c, a cell envelope-associated protein, was able to enhance the intracellular survival of recombinant M. smegmatis. Enhanced growth was not found to be the result of an increased resistance to intracellular stresses, as growth of the Rv3402c expressing strain was unaffected by iron depletion, H2O2 exposure, or acidic conditions. Colonization of macrophages by M. smegmatis expressing Rv3402c was associated with substantial cell death and significantly greater amount of TNF-? and IL-1? compared with controls. Rv3402c-induced TNF-? and IL-1? production was found to be mediated by NF-?B, ERK and p38 pathway in macrophages. In summary, our study suggests that Rv3402c delivered in a live M. smegmatis vehicle can modify the cytokines profile of macrophage, promote host cell death and enhance the persistence of mycobacterium within host cells.
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Dissemination and serotype modification potential of pSFxv_2, an O-antigen PEtN modification plasmid in Shigella flexneri.
Glycobiology
PUBLISHED: 12-29-2013
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The O-antigens of all S. flexneri serotypes, except serotype 6, share a linear tetrasaccharide repeat composed of one N-acetylglucosamine and three L-rhamnose residues, and differences between the serotypes are due to modification of various monosaccharide residues with glucosyl and/or O-acetyl and/or phosphoethanolamine (PEtN) groups. Plasmid-borne opt (formerly lpt-O) gene encoding a PEtN transferase which modifies the O-antigens of S. flexneri serotype X, 4a and Y strains and converts the hosts into MASF IV-1 (E1037) positive variant (v) Xv, 4av and Yv serotypes, respectively. In this study we showed that the opt-carrying plasmid pSFxv_2 can transform strains of all S. flexneri serotypes (1 to 6) to confer them with the MASF IV-1 epitope recognized by monoclonal antibody MASF IV-1 and typing antiserum IV. The transformants possessed modified O-antigens with a PEtN group(s) at position 3 of one or two rhamnose residues. In some serotypes, the PEtN modification competed or/and interfered with glucosylation and O-acetylation at the same or its neighboring sugar residue. We also showed that the plasmid pSFxv_2 is mobilizable to other S. flexneri strains by conjugation. Although pSFxv_2-harboring S. flexneri strains found in clinical infections are restricted to serotypes Xv, 4av, Yv and, possibly, 6v, our results demonstrate a high potential of dissemination of this plasmid in S. flexneri and emergence of new S. flexneri serotypes.
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Amide-I Characteristics of Helical ?-Peptides by Linear Infrared Measurement and Computations.
J Phys Chem B
PUBLISHED: 12-23-2013
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In this work, we have examined the amide-I characteristics of three ?-peptide oligomers in typical helical conformations (two in 14-helix and one in 12/10-helix), solvated in water, methanol, and chloroform, respectively. Local-mode frequencies and their distributions were computed using a molecular-mechanics force field based frequency map that was constructed on the basis of molecular dynamics simulations. The local-mode frequencies were found to be determined primarily by peptide backbone and side chain, rather by solvent, suggesting their local structural sensitivities. Intermode vibrational couplings computed using a transition dipole scheme were found to be very sensitive to peptide conformation, with their signs and magnitudes varying periodically along the peptide chain. Linear infrared absorption spectra of the three peptides, simulated using a frequency-frequency time-correlation function method, were found to be in fair agreement with experimental results. Normalized potential energy distribution analysis indicated that the amide-I mode can delocalize over a few amide units. However, the IR band structure appears to be more sophisticated in helical ?-peptides than in helical ?-peptides.
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Progress of FtsZ Inhibitors as Novel Antibiotics Leads.
Crit. Rev. Eukaryot. Gene Expr.
PUBLISHED: 11-26-2013
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Bacterial cell division is an attractive target for new antibiotics. FtsZ is a major cytoskeletal protein widespread among archaea and bacteria. FtsZ has a filament-forming GTPase and a structural homologue of eukaryotic tubulin. FtsZ has been validated as a target for antibiotics. This review summarizes the chemical features, binding sites, mechanisms of action, and minimum inhibitory concentration of FtsZ inhibitors.
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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.