JoVE Visualize What is visualize?
Stop Reading. Start Watching.
Advanced Search
Stop Reading. Start Watching.
Regular Search
Find video protocols related to scientific articles indexed in Pubmed.
Graphitic carbon nitride based nanocomposites: a review.
Nanoscale
PUBLISHED: 11-20-2014
Show Abstract
Hide Abstract
Graphitic carbon nitride (g-C3N4), as an intriguing earth-abundant visible light photocatalyst, possesses a unique two-dimensional structure, excellent chemical stability and tunable electronic structure. Pure g-C3N4 suffers from rapid recombination of photo-generated electron-hole pairs resulting in low photocatalytic activity. Because of the unique electronic structure, the g-C3N4 could act as an eminent candidate for coupling with various functional materials to enhance the performance. According to the discrepancies in the photocatalytic mechanism and process, six primary systems of g-C3N4-based nanocomposites can be classified and summarized: namely, the g-C3N4 based metal-free heterojunction, the g-C3N4/single metal oxide (metal sulfide) heterojunction, g-C3N4/composite oxide, the g-C3N4/halide heterojunction, g-C3N4/noble metal heterostructures, and the g-C3N4 based complex system. Apart from the depiction of the fabrication methods, heterojunction structure and multifunctional application of the g-C3N4-based nanocomposites, we emphasize and elaborate on the underlying mechanisms in the photocatalytic activity enhancement of g-C3N4-based nanocomposites. The unique functions of the p-n junction (semiconductor/semiconductor heterostructures), the Schottky junction (metal/semiconductor heterostructures), the surface plasmon resonance (SPR) effect, photosensitization, superconductivity, etc. are utilized in the photocatalytic processes. Furthermore, the enhanced performance of g-C3N4-based nanocomposites has been widely employed in environmental and energetic applications such as photocatalytic degradation of pollutants, photocatalytic hydrogen generation, carbon dioxide reduction, disinfection, and supercapacitors. This critical review ends with a summary and some perspectives on the challenges and new directions in exploring g-C3N4-based advanced nanomaterials.
Related JoVE Video
[Nucleolus expression in diabetic cardiomyopathy].
Zhong Nan Da Xue Xue Bao Yi Xue Ban
PUBLISHED: 10-31-2014
Show Abstract
Hide Abstract
To investigate the nucleolus expression in the diabetic cardiomyopathy.
Related JoVE Video
Interaction of sleep quality and sleep duration on glycemic control in patients with type 2 diabetes mellitus.
Chin. Med. J.
PUBLISHED: 10-16-2014
Show Abstract
Hide Abstract
Copious evidence from epidemiological and laboratory studies has revealed that sleep status is associated with glucose intolerance, insulin resistance, thus increasing the risk of developing type 2 diabetes. The aim of this study was to reveal the interaction of sleep quality and sleep quantity on glycemic control in patients with type 2 diabetes mellitus.
Related JoVE Video
Crystal structure of poly[aqua-[?-1,1'-(9,9-dimethyl-9H-fluoren-2,7-di-yl)di-1H-imidazole](?-naphthalene-1,4-di-carboxyl-ato)nickel(II)].
Acta Crystallogr Sect E Struct Rep Online
PUBLISHED: 09-01-2014
Show Abstract
Hide Abstract
In the title compound, [Ni(C12H6O4)(C21H18N4)(H2O)] n , the Ni(II) cation is coordinated by three carboxyl-ate O atoms of two naphthalene-1,4-di-carboxyl-ate anions, one water mol-ecule and two N atoms of two 1,1'-(9,9-dimethyl-9H-fluoren-2,7-di-yl)di-1H-imidazole (DFDI) ligands, giving rise to a slightly distorted octa-hedral geometry. The Ni(II) ions are linked by the DFDI ligands into chains, which are further connected by the carboxyl-ate anions into double chains that elongate in the the b-axis direction. These double chains are linked by centrosymmetric pairs of O-H?O hydrogen bonds into layers parallel to (10-1). The asymmetric unit consists of one crystallographically independent Ni(II) cation, one carboxyl-ate and one DFDI ligand, as well as of one water mol-ecule, all of them located in general positions.
Related JoVE Video
Crystal structure of poly[{?-N,N'-bis[(pyridin-4-yl)meth-yl]oxalamide}-?-oxalato-cobalt(II)].
Acta Crystallogr Sect E Struct Rep Online
PUBLISHED: 09-01-2014
Show Abstract
Hide Abstract
In the polymeric title compound, [Co(C2O4)(C14H14N4O2)] n , the Co(II) atom is six-coordinated by two N atoms from symmetry-related bis-[(pyridin-4-yl)meth-yl]oxalamide (BPMO) ligands and four O atoms from two centrosymmetric oxalate anions in a distorted octa-hedral coordination geometry. The Co(II) atoms are linked by the oxalate anions into a chain running parallel to [100]. The chains are linked by the BPMO ligands into a three-dimensional architecture. In addition, N-H?O hydrogen bonds stabilize the crystal packing.
Related JoVE Video
Evaluating tumor metastatic potential by imaging intratumoral acidosis via pH-activatable near-infrared fluorescent probe.
Int. J. Cancer
PUBLISHED: 08-23-2014
Show Abstract
Hide Abstract
Metastasis accounts for the vast majority of cancer deaths. To minimize metastasis-associated mortality, it is crucially important to evaluate the metastatic potential (M.P.), that is, defined as a tendency of a primary tumor to colonize a distant organ. Dysregulated pH in solid tumors, especially the acidification of extracellular pH (pHe ) promotes dormant metastasis by driving protease-mediated digestion, disrupting cell-matrix interaction and increasing migration of cancer cells. Therefore, imaging intratumoral acidosis creates a unique opportunity to evaluate the M.P. In this work, a novel pH activatable probe was developed, in which two near-infrared (NIR) fluorophores were conjugated via a flexible and acid liable linkage. While the fluorescence of this probe is quenched due to intramolecular dimeric aggregate under neutral environment, the cleavage of pH liable linkage with the concomitant disruption of aggregates in acidic tumor microenvironment results in a remarkable fluorescence enhancement. This probe not only visualized the primary tumors with high target to background (T/B) signal ratio in vivo, but also revealed the correlation between the M.P. and acidosis distribution pattern in tumor. While the acidosis locate dispersedly at tumor periphery in highly metastatic tumor, it distribute more widely in lowly metastatic tumor and the acidification degree increases substantially from the margin to core areas. This pH activatable NIR fluorescent probe holds the potential to evaluate the M.P., monitor the therapeutic response and predict the prognosis by delineating acidosis in tumors.
Related JoVE Video
Isocorydine derivatives and their anticancer activities.
Molecules
PUBLISHED: 08-12-2014
Show Abstract
Hide Abstract
In order to improve the anticancer activity of isocorydine (ICD), ten isocorydine derivatives were prepared through chemical structure modifications, and their in vitro and in vivo activities were experimentally investigated. 8-Amino-isocorydine (8) and 6a,7-dihydrogen-isocorydione (10) could inhibit the growth of human lung (A549), gastric (SGC7901) and liver (HepG2) cancer cell lines in vitro. Isocorydione (2) could inhibit the tumor growth of murine sarcoma S180-bearing mice, and 8-acetamino-isocorydine (11), a pro-drug of 8-amino-isocorydine (8), which is instable in water solution at room temperature, had a good inhibitory effect on murine hepatoma H22-induced tumors. The results suggested that the isocorydine structural modifications at C-8 could significantly improve the biological activity of this alkaloid, indicating its suitability as a lead compound in the development of an effective anticancer agent.
Related JoVE Video
Luteimonas dalianensis sp. nov., an obligate marine bacterium isolated from seawater.
J. Microbiol.
PUBLISHED: 07-09-2014
Show Abstract
Hide Abstract
A marine bacterial strain, designated OB44-3(T), was isolated from a crude oil-contaminated seawater sample collected near Dalian Bay, China. Cells of strain OB44-3(T) were Gramnegative, aerobic, rod-shaped, and oxidase- and catalasepositive. The major fatty acids were branched-chain saturated iso-C15:0 (27.9%) and unsaturated iso-C17:1 ?9c (14.8%). The DNA G+C content was 64.6 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain OB44-3(T) was a member of the genus Luteimonas (95-96% 16S rRNA gene sequence similarity); its closest neighbors were the type strains of Luteimonas terricola (96% sequence similarity), Luteimonas mephitis (96%), and Luteimonas lutimaris (96%). On the basis of phenotypic, chemotaxonomic, and phylogenetic distinctiveness, strain OB44-3(T) was considered to represent a novel species of the genus Luteimonas. The name Luteimonas dalianensis sp. nov. is proposed, with strain OB44-3(T) (=CGMCC 1.12191(T) =JCM 18136(T)) as the type strain.
Related JoVE Video
Facile synthesis of organic-inorganic layered nanojunctions of g-C3N4/(BiO)2CO3 as efficient visible light photocatalyst.
Dalton Trans
PUBLISHED: 07-01-2014
Show Abstract
Hide Abstract
Novel g-C3N4/(BiO)2CO3 organic-inorganic nanojunctioned photocatalysts were synthesized by in situ depositing (BiO)2CO3 nanoflakes onto the surface of g-C3N4 nanosheets through a one-pot efficient capture of atmospheric CO2 method at room temperature. The as-synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (DRS), N2 adsorption-desorption analysis and electron spin resonance (ESR). The photocatalytic activity of as-synthesized samples was evaluated by degrading Rhodamine B (RhB) and phenol in aqueous solution under visible-light irradiation. The g-C3N4/(BiO)2CO3 nanojunctions showed much higher visible-light photocatalytic activity than those of pure g-C3N4 and (BiO)2CO3 for the degradation of RhB and phenol. The enhanced photocatalytic activity can be mainly ascribed to the well-matched band structures, dye photosensitization and efficient crystal facets coupling interaction between g-C3N4 {002} and (BiO)2CO3 {002}. The ?O2(-) radicals were identified as the main active species. Furthermore, the pure (BiO)2CO3 with highly exposed {002} crystal facets also exhibited excellent visible-light photoactivity for the degradation of RhB, which can be originated from the indirect dye photosensitization. The present work could provide a new strategy for the efficient utilization of atmospheric CO2 in green synthetic chemistry.
Related JoVE Video
Enhancing the photocatalytic activity of bulk g-C3N4 by introducing mesoporous structure and hybridizing with graphene.
J Colloid Interface Sci
PUBLISHED: 06-20-2014
Show Abstract
Hide Abstract
Bulk graphitic carbon nitride (CN) suffers from small surface area and high recombination of charge carriers, which result in low photocatalytic activity. To enhance the activity of g-C3N4, the surface area should be enlarged and charge carrier separation should be promoted. In this work, a combined strategy was employed to dramatically enhance the activity of bulk g-C3N4 by simultaneously introducing mesoporous structure and hybridizing with graphene/graphene oxide. The mesoporous g-C3N4/graphene (MCN-G) and mesoporous g-C3N4/graphene oxide (MCN-GO) nanocomposites with enhanced photocatalytic activity (NO removal ratio of 64.9% and 60.7%) were fabricated via a facile sonochemical method. The visible light-harvesting ability of MCN-G and MCN-GO hybrids was enhanced and the conduction band was negatively shifted when 1.0 wt% graphene/graphene oxide was incorporated into the matrix of MCN. As electronic conductive channels, the G/GO sheets could efficiently facilitate the separation of chare carriers. MCN-G and MCN-GO exhibited drastically enhanced visible light photocatalytic activity toward NO removal. The NO removal ratio increased from 16.8% for CN to 64.9% for MCN-G and 60.7% for MCN-GO. This enhanced photocatalytic activity could be attributed to the increased surface area and pore volume, improved visible light utilization, enhanced reduction power of electrons, and promoted separation of charge carriers. This work demonstrates that a combined strategy is extremely effective for the development of active photocatalysts in environmental and energetic applications.
Related JoVE Video
A semimetal bismuth element as a direct plasmonic photocatalyst.
Chem. Commun. (Camb.)
PUBLISHED: 06-17-2014
Show Abstract
Hide Abstract
The bismuth element synthesized by a facile chemical solution method exhibited an admirable and stable photocatalytic activity towards the removal of NO under 280 nm light irradiation due to the surface plasmon resonance mediated direct photocatalysis, and most strikingly, showed a catalytic "memory" capability following illumination.
Related JoVE Video
Hypoxia-induced cytosolic calcium influx is mediated primarily by the reverse mode of Na+/Ca2+ exchanger in smooth muscle cells of fetal small pulmonary arteries.
J. Obstet. Gynaecol. Res.
PUBLISHED: 06-04-2014
Show Abstract
Hide Abstract
Constriction of small pulmonary arteries and high resistance of pulmonary circulation are important for maintaining fetal circulation before birth. In this study, we investigated how cytosolic free calcium concentration ([Ca(2+)]i) in fetal lamb small pulmonary artery smooth muscle cells (SPASMC) was affected by hypoxia and regulated by calcium pumps during this process.
Related JoVE Video
Prognostic value of microRNA-100 in esophageal squamous cell carcinoma.
J. Surg. Res.
PUBLISHED: 05-11-2014
Show Abstract
Hide Abstract
MicroRNA-100 (miR-100) has been demonstrated to be implicated in tumorigenesis and tumor progression of human esophageal squamous cell carcinoma (ESCC). However, its expression patterns in ESCC are controversial and its prognostic value in this malignancy has not been fully elucidated. The aim of this study was to investigate the expression and clinical significance of miR-100 in ESCC.
Related JoVE Video
Clinical value of multi-slice spiral computed tomography angiography and three-dimensional reconstruction in the diagnosis of double aortic arch.
Exp Ther Med
PUBLISHED: 04-29-2014
Show Abstract
Hide Abstract
The aim of this study was to evaluate the clincal value of multi-slice spiral computed tomography (MSCT) in the diagnosis of double aortic arch (DAA) and analyze the associated angiography and 3D reconstruction imaging to increase the accuracy of DAA diagnosis. Clinical and imaging data from 15 patients diagnosed with DAA by MSCT were summarized and compared with the corresponding surgical observations. The DAA diagnosis by MSCT for the 15 patients was confirmed by the surgical observations. A total of 13 cases were categorized as type I (double arches are open), including nine with a larger right arch, two with a larger left arch and two with balanced arches. Two cases were categorized as type II (one atretic arch), characterized by left atretic arch. Among the 15 patients, ultrasound diagnosis succeeded in nine cases and failed in the rest. A single malformation was identified in only two cases, whereas the rest had single or multiple combination(s) of intracardiac and extracardiac malformations, including seven with different levels of tracheobronchial stenosis. MSCT was demonstrated to precisely diagnose DAA complicated by malformation and tracheobronchial stenosis. MSCT is an essential therapeutic strategy and serves as a primary method in DAA diagnosis.
Related JoVE Video
Effects of two genes coding squamous cell carcinoma antigen on the diagnosis and treatment of cervical squamous cell carcinoma.
Pak J Med Sci
PUBLISHED: 04-29-2014
Show Abstract
Hide Abstract
To study the effects of expressions of SCCA1 and SCCA2 in cervical squamous cell carcinoma on its diagnosis, treatment evaluation and prognosis analysis. M ethod s : Seventy-six cervical squamous cell carcinoma patients enrolled in our hospital from October 2011 to April 2013 were selected, and another 76 healthy females (without cervical tissue lesions) were enrolled as the control. SCCA1 and SCCA2 expressions in the two groups were compared by RT-PCR. The serodiagnosis results before and after chemotherapy were compared to clarify the effects of SCCA2 expression.
Related JoVE Video
Comparative pharmacokinetic study of four major components after oral administration of pure compounds, herbs and Si-Ni-San to rats.
Xenobiotica
PUBLISHED: 03-18-2014
Show Abstract
Hide Abstract
1.?The pharmacokinetic differences of paeoniflorin, naringin, naringenin and glycyrrhetinic acid (GA) following oral administration of pure compounds, single herbs and Si-Ni-San (SNS) decoction to rats were studied. Blood samples were analyzed with a validated UPLC-MS/MS method. Student's t-test was used for the statistical comparison. 2.?The Cmax and AUC0-? were 1470±434?ng/mL and 4663±916?ng?h/mL for paeoniflorin, 64.29±59.21?ng/mL and 311.8±131.8?ng?h/mL for naringin, 244.2±138.8?ng/mL and 4761±3167?ng?h/mL for naringenin, and 1183±294?ng/mL and 38 994±14 377?ng?h/mL for GA after oral administration of paeoniflorin, naringin and glycyrrhizic acid. The Cmax and AUC0-? were 812.6±259.6?ng/mL and 2489±817?ng?h/mL for paeoniflorin, 344.3±234.9?ng/mL and 1479±531?ng?h/mL for naringin, 981.9±465.4?ng/mL and 12?284±6378?ng?h/mL for naringenin, and 3164±742?ng/mL and 78 817±16?707?ng?h/mL for GA after oral administration of SNS decoction. 3.?There were significant differences between the pharmacokinetic behavior after oral administration of SNS decoction compared with pure components or herbs. The results indicated that some components in the other herbs of SNS had a pharmacokinetic interaction with paeoniflorin, naringin, naringenin and GA.
Related JoVE Video
A novel channel selection method for multiple motion classification using high-density electromyography.
Biomed Eng Online
PUBLISHED: 03-06-2014
Show Abstract
Hide Abstract
Selecting an appropriate number of surface electromyography (EMG) channels with desired classification performance and determining the optimal placement of EMG electrodes would be necessary and important in practical myoelectric control. In previous studies, several methods such as sequential forward selection (SFS) and Fisher-Markov selector (FMS) have been used to select the appropriate number of EMG channels for a control system. These exiting methods are dependent on either EMG features and/or classification algorithms, which means that when using different channel features or classification algorithm, the selected channels would be changed. In this study, a new method named multi-class common spatial pattern (MCCSP) was proposed for EMG selection in EMG pattern-recognition-based movement classification. Since MCCSP is independent on specific EMG features and classification algorithms, it would be more convenient for channel selection in developing an EMG control system than the exiting methods.
Related JoVE Video
Synthesis and optimizable electrochemical performance of reduced graphene oxide wrapped mesoporous TiO? microspheres.
Nanoscale
PUBLISHED: 03-06-2014
Show Abstract
Hide Abstract
A facile microwave solvothermal process is developed to prepare an anatase TiO2 anode material that maintains multiple properties including high surface area, high crystallinity, uniform mesoporous, perfect microspheres and uniform particle size. Using this fine anatase TiO? product, a TiO?/RGO (RGO: reduced graphene oxide) hybrid material is prepared under UV-light irradiation. Incorporation of RGO improves the electrochemical kinetics of the TiO? microspheres, which results in superior electrochemical performance in terms of specific capacity, rate capability and cycle stability. The material shows a discharge capacity of 155.8 mA h g(-1) at the 5 C rate. Even at the 60 C rate, a high discharge capacity of 83.6 mA h g(-1) is still obtained which is two times higher than that of pristine mesoporous TiO?.
Related JoVE Video
Growth mechanism and photocatalytic activity of self-organized N-doped (BiO)?CO? hierarchical nanosheet microspheres from bismuth citrate and urea.
Dalton Trans
PUBLISHED: 02-11-2014
Show Abstract
Hide Abstract
Synthesis of nano-/microstructured functional materials with 3D hierarchical microspheres structure has provided new opportunities for optimizing their physical and chemical properties. This work revealed a new growth mechanism of self-organized N-doped (BiO)2CO3 hierarchical microspheres which were fabricated by hydrothermal treatment of bismuth citrate and urea without an additive. Based on time-dependent observation, several evolution processes were believed to account for the formation of the self-organized N-doped (BiO)2CO3 hierarchical microspheres. Initially, crystallized (BiO)4CO3(OH)2 particles were formed during the nucleation and crystallization processes. Subsequently, the intermediate (BiO)4CO3(OH)2 reacted with CO3(2-) to generate (BiO)2CO3 growth nuclei on the surface of the CO2 bubbles which can act as heterogeneous nucleation centers. Next, the (BiO)2CO3 growth nuclei aggregated together after the consumption of CO2 bubbles with the increased concentration of OH(-) and further grew to be nanosheets. The microspheres constructed by small nanosheets further grew with the consumption of small particles. Finally, all (BiO)4CO3(OH)2 transformed to the (BiO)2CO3 phase, accompanied by the doping of N element into the lattice of (BiO)2CO3, and thereby, the well-defined N-doped (BiO)2CO3 hierarchical microspheres were shaped. Depending on the distance between neighboring CO2 bubbles, the resulting microspheres can be linked or dispersed. Besides, the gradual release of CO2 bubbles and CO3(2-) played a crucial role in controlling the nucleation and growth process, resulting in different sizes of microspheres. The fabricated N-doped (BiO)2CO3 hierarchical microspheres displayed admirably efficient and durable photocatalytic activity under both UV and visible light towards removal of NO, which is mainly attributed to the introduction of N element and the special hierarchical structure. This work provides new insights into the controlled synthesis of photocatalytic nano/microstructures for potential environmental and energetic applications.
Related JoVE Video
Ferrocene-modified carbon nitride for direct oxidation of benzene to phenol with visible light.
ChemSusChem
PUBLISHED: 01-29-2014
Show Abstract
Hide Abstract
Ferrocene moieties were heterogenized onto carbon nitride polymers by a covalent -C=N- linkage bridging the two conjugation systems, enabling the merging of the redox function of ferrocene with carbon nitride photocatalysis to construct a heterogeneous Photo-Fenton system for green organocatalysis at neutral conditions. The synergistic donor-acceptor interaction between the carbon nitride matrix and ferrocene group, improved exciton splitting, and coupled photocatalytic performance allowed the direct synthesis of phenol from benzene in the presence of H2 O2 under visible light irradiation. This innovative modification method will offer an avenue to construct functionalized two-dimensional polymers useful also for other green synthesis processes using solar irradiation.
Related JoVE Video
Growth of BiOBr nanosheets on C3N4 nanosheets to construct two-dimensional nanojunctions with enhanced photoreactivity for NO removal.
J Colloid Interface Sci
PUBLISHED: 01-28-2014
Show Abstract
Hide Abstract
The development of approaches to effectively separate the photo-induced charge carriers is a key strategy to promote the photocatalytic activity of semiconductor photocatalysts. This work represents the construction of novel two-dimensional (2D) BiOBr/C3N4 nanojunctions by the growth of BiOBr nanosheets on the surface of C3N4 nanosheets at room temperature. The samples were characterized by XRD, FT-IR, TEM, UV-vis DRS and PL. The photocatalytic activity of the samples was evaluated by the removal of NO in air under visible light irradiation. The results indicated that electronic coupling took place between the {001} plane of BiOBr and {002} plane of C3N4. The BiOBr/C3N4 nanojunctions exhibited enhanced visible light photocatalytic activity compared with pure BiOBr and C3N4. The enhanced photoactivity can be mainly ascribed to the efficient separation and transportation of photo-induced electrons and holes due to the well-coupled crystal planes and well-matched band structures. The present work could provide new insights into the design and construction of 2D nanojunctions with well-matched crystal planes and band structures for efficient visible light photocatalysis.
Related JoVE Video
Simultaneous determination of neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid and geniposide in rat plasma by UPLC-MS/MS and its application to a pharmacokinetic study after administration of Reduning injection.
Biomed. Chromatogr.
PUBLISHED: 01-27-2014
Show Abstract
Hide Abstract
A simple, specific and sensitive ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was established and validated for simultaneous determination of neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid and geniposide in rat plasma using puerarin as an internal standard (IS). Plasma samples were pretreated by a one-step direct protein precipitation procedure with acetonitrile after acidified using as little as 50??L plasma. Chromatographic separation was performed on an Acquity BEH C18 column (100?×?2.1?mm, 1.7?µm) at a flow rate of 0.2?mL/min by a gradient elution, using 0.2% acetic acid-methanol as mobile phase. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring via electrospray ionization source with negative ion mode. Calibration curves showed good linearity (r?>?0.995) over wide concentration ranges. The intra- and inter-day precisions were <15%, and the accuracy was within ±8.0%. The validated method was successfully applied to a pharmacokinetic study of the four bioactive components in rats after intravenous administration of Reduning injection. Copyright © 2014 John Wiley & Sons, Ltd.
Related JoVE Video
A derivative photoelectrochemical sensing platform for herbicide acetochlor based on TiO?-poly (3-hexylthiophene)-ionic liquid nanocomposite film modified electrodes.
Talanta
PUBLISHED: 01-22-2014
Show Abstract
Hide Abstract
Nonelectroactive acetochlor can be indirectly determined through the photocatalytical degradation of acetochlor. A derivative visible light photoelectrochemical sensor for indirect detection of the herbicide acetochlor using TiO2-poly(3-hexylthiophene)-ionic liquid nanocomposite is constructed. Poly(3-hexylthiophene) (P3HT) was synthesized via chemical oxidative polymerization with anhydrous FeCl3 as oxidant, 3-hexylthiophene as monomer, chloroform as solvent, and the functional TiO2 nanoparticles were facilely prepared by blending TiO2 nanoparticles and P3HT at room temperature ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate solution. Operational parameters, including the photolysis time, ratios of TiO2 to P3HT, bias voltage and pH of buffer solution have been optimized. Under optimal conditions, the proposed photoelectrochemical method could detect acetochlor ranging from 0.5 to 20 ?mol L(-1) with a detection limit of 0.2 nmol L(-1) at a signal-to-noise ratio of 3. The assay results of acetochlor in water samples with the proposed method were in acceptable agreement with those of the gas chromatograph-mass spectrometer (GC-MS) method. The promising sensor opens a new opportunity for fast, portable, and sensitive analysis of acetochlor in environmental samples.
Related JoVE Video
HSF-1 is involved in attenuating the release of inflammatory cytokines induced by LPS through regulating autophagy.
Shock
PUBLISHED: 01-17-2014
Show Abstract
Hide Abstract
Autophagy plays a protective role in endotoxemic mice. Heat shock factor 1 (HSF-1) also plays a crucial protective role in endotoxemic mice by decreasing inflammatory cytokines. The purpose of this study was to determine whether HSF-1 is involved in attenuating the release of inflammatory cytokines in lipopolysaccharide (LPS)-stimulated mice and peritoneal macrophages (PMs) through regulating autophagy activity. Autophagosome formation in HSF-1(+/+) and HSF-1(-/-) mice and PMs stimulated by LPS was examined by Western blotting and immunofluorescence. Lipopolysaccharide-induced autophagy and inflammatory cytokines were examined in HSF-1(+/+) and HSF-1(-/-) PMs treated with 3-methyladenine (3-MA) or rapamycin. Results showed that LPS-induced autophagy was elevated transiently at 12 h but declined at 24 h in the livers and lungs of mice. Higher levels of inflammatory cytokines and lower autophagy activity were detected in HSF-1(-/-) mice and PMs compared with HSF-1(+/+) mice and PMs. Interestingly, LPS-induced release of inflammatory cytokines did not further increase in HSF-1(-/-) PMs treated with 3-MA but aggravated in HSF-1(+/+) PMs. Lipopolysaccharide-induced autophagy did not decrease in HSF-1(-/-) PMs treated with 3-MA but decreased in HSF-1 PMs(+/+). Taken together, our results suggested that HSF-1 attenuated the release of inflammatory cytokines induced by LPS by regulating autophagy activity.
Related JoVE Video
Nucleolin involved in myocardial ischaemic preconditioning via post-transcriptional control of HSPA1A expression.
Cardiovasc. Res.
PUBLISHED: 01-16-2014
Show Abstract
Hide Abstract
Recent studies have identified the critical roles of nucleolin in a variety of cellular processes, including regulation of viral replication and tumour formation. However, the possible roles of nucleolin in myocardial preconditioning remain undefined.
Related JoVE Video
Arabidopsis WRKY57 functions as a node of convergence for jasmonic acid- and auxin-mediated signaling in jasmonic acid-induced leaf senescence.
Plant Cell
PUBLISHED: 01-14-2014
Show Abstract
Hide Abstract
Leaf senescence is regulated by diverse developmental and environmental factors. Exogenous jasmonic acid (JA) can induce leaf senescence, whereas auxin suppresses this physiological process. Crosstalk between JA and auxin signaling has been well studied, but not during JA-induced leaf senescence. Here, we found that upon methyl jasmonate treatment, Arabidopsis thaliana wrky57 mutants produced typical leaf senescence symptoms, such as yellowing leaves, low chlorophyll content, and high cell death rates. Further investigation suggested that senescence-associated genes were upregulated in the wrky57 mutants. Chromatin immunoprecipitation experiments revealed that WRKY57 directly binds to the promoters of SENESCENCE4 and SENESCENCE-ASSOCIATED GENE12 and represses their transcription. In vivo and in vitro experiments suggested that WRKY57 interacts with JASMONATE ZIM-DOMAIN4/8 (JAZ4/8) and the AUX/IAA protein IAA29, repressors of the JA and auxin signaling pathways, respectively. Consistent with the opposing functions of JA and auxin in JA-induced leaf senescence, JAZ4/8 and IAA29 also displayed opposite functions in JA-induced leaf senescence and competitively interacted with WRKY57. Our results suggested that the JA-induced leaf senescence process can be antagonized by auxin via WRKY57. Moreover, WRKY57 protein levels were downregulated by JA but upregulated by auxin. Therefore, as a repressor in JA-induced leaf senescence, WRKY57 is a common component of the JA- and auxin-mediated signaling pathways.
Related JoVE Video
CO2-induced micelle to vesicle transition in zwitterionic-anionic surfactant systems.
Phys Chem Chem Phys
PUBLISHED: 01-14-2014
Show Abstract
Hide Abstract
Study of micelle to vesicle transition (MVT) is of great importance from both theoretical and practical points of view. In this work, we studied the effect of compressed CO2 on the aggregation behavior of zwitterionic-anionic (DSB (dodecyl sulfonatebetaine)-AOT(sodium bis(2-ethylhexyl) sulfosuccinate)) mixed surfactants in aqueous solution by means of direct observation, turbidity, steady-state fluorescence, fluorescence quantum yield, and entrapment quantity of vesicles. Interestingly, all the methods show that compressed CO2 can induce MVT in this zwitterionic-anionic surfactant system. The CO2-induced MVT is reversible and the degree of MVT can be easily tuned by controlling the operation pressure. Further studies show that the pH decrease and dissolution of gas molecules in the surfactant film co-contribute to the MVT, and a possible mechanism for the CO2-induced MVT was proposed based on the experimental results.
Related JoVE Video
High-resolution quantification of hepatitis C virus genome-wide mutation load and its correlation with the outcome of peginterferon-alpha2a and ribavirin combination therapy.
PLoS ONE
PUBLISHED: 01-01-2014
Show Abstract
Hide Abstract
Hepatitis C virus (HCV) is a highly mutable RNA virus and circulates as a heterogeneous population in individual patients. The magnitude of such population heterogeneity has long been proposed to be linked with diverse clinical phenotypes, including antiviral therapy. Yet data accumulated thus far are fairly inconclusive. By the integration of long RT-PCR with 454 sequencing, we have built a pipeline optimized for the quantification of HCV genome-wide mutation load at 1% resolution of mutation frequency, followed by a retrospective study to examine the role of HCV mutation load in peginterferon-alpha2a and ribavirin combination antiviral therapy. Genome-wide HCV mutation load varied widely with a range from 92 to 1639 mutations and presented a Poisson distribution among 56 patients (Kolmogorov-Smirnov statistic ?=?0.078, p?=?0.25). Patients achieving sustained virological response (n?=?26) had significantly lower mutation loads than that in null responders (n?=?30) (mean and standard derivation: 524±279 vs. 805±271, p?=?0.00035). All 36,818 mutations detected in 56 patients displayed a power-law distribution in terms of mutation frequency in viral population. The low-frequency mutation load, but not the high-frequency load, was proportional firmly to the total mutation load. In-depth analyses revealed that intra-patient HCV population structure was shaped by multiple factors, including immune pressure, strain difference and genetic drift. These findings explain previous conflicting reports using low-resolution methods and highlight a dominant role of natural selection in response to therapeutic intervention. By attaining its signatures from complex interaction between host and virus, the high-resolution quantification of HCV mutation load predicts outcomes from interferon-based antiviral therapy and could also be a potential biomarker in other clinical settings.
Related JoVE Video
Cutting force predication based on integration of symmetric fuzzy number and finite element method.
ScientificWorldJournal
PUBLISHED: 01-01-2014
Show Abstract
Hide Abstract
In the process of turning, pointing at the uncertain phenomenon of cutting which is caused by the disturbance of random factors, for determining the uncertain scope of cutting force, the integrated symmetric fuzzy number and the finite element method (FEM) are used in the prediction of cutting force. The method used symmetric fuzzy number to establish fuzzy function between cutting force and three factors and obtained the uncertain interval of cutting force by linear programming. At the same time, the change curve of cutting force with time was directly simulated by using thermal-mechanical coupling FEM; also the nonuniform stress field and temperature distribution of workpiece, tool, and chip under the action of thermal-mechanical coupling were simulated. The experimental result shows that the method is effective for the uncertain prediction of cutting force.
Related JoVE Video
In situ construction of g-C3N4/g-C3N4 metal-free heterojunction for enhanced visible-light photocatalysis.
ACS Appl Mater Interfaces
PUBLISHED: 11-01-2013
Show Abstract
Hide Abstract
The photocatalytic performance of the star photocatalyst g-C3N4 was restricted by the low efficiency because of the fast charge recombination. The present work developed a facile in situ method to construct g-C3N4/g-C3N4 metal-free isotype heterojunction with molecular composite precursors with the aim to greatly promote the charge separation. Considering the fact that g-C3N4 samples prepared from urea and thiourea separately have different band structure, the molecular composite precursors of urea and thiourea were treated simultaneously under the same thermal conditions, in situ creating a novel layered g-C3N4/g-C3N4 metal-free heterojunction (g-g CN heterojunction). This synthesis method is facile, economic, and environmentally benign using easily available earth-abundant green precursors. The confirmation of isotype g-g CN heterojunction was based on XRD, HRTEM, valence band XPS, ns-level PL, photocurrent, and EIS measurement. Upon visible-light irradiation, the photogenerated electrons transfer from g-C3N4 (thiourea) to g-C3N4 (urea) driven by the conduction band offset of 0.10 eV, whereas the photogenerated holes transfer from g-C3N4 (urea) to g-C3N4 (thiourea) driven by the valence band offset of 0.40 eV. The potential difference between the two g-C3N4 components in the heterojunction is the main driving force for efficient charge separation and transfer. For the removal of NO in air, the g-g CN heterojunction exhibited significantly enhanced visible light photocatalytic activity over g-C3N4 alone and physical mixture of g-C3N4 samples. The enhanced photocatalytic performance of g-g CN isotype heterojunction can be directly ascribed to efficient charge separation and transfer across the heterojunction interface as well as prolonged lifetime of charge carriers. This work demonstrated that rational design and construction of isotype heterojunction could open up a new avenue for the development of new efficient visible-light photocatalysts.
Related JoVE Video
Pattern recognition based forearm motion classification for patients with chronic hemiparesis.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 10-11-2013
Show Abstract
Hide Abstract
To make full use of electromyography (EMG) that contains rich information of muscular activities in active rehabilitation for motor hemiparetic patients, a couple of recent studies have explored the feasibility of applying pattern recognition technique to the classification of multiple motion classes for stroke survivors and reported some promising results. However, it still remains unclear if kinematics signals could also bring good motion classification performance, particularly for patients after traumatic brain damage. In this study, the kinematics signals was used for motion classification analysis in three stroke survivors and two patients after traumatic brain injury, and compared with EMG. The results showed that an average classification error of 7.9±6.8% for the affected arm over all subjects could be achieved with a linear classifier when they performed multiple fine movements, 7.9% lower than that when using EMG. With either kind of signals, the motor control ability of the affected arm degraded significantly in comparison to the intact side. The preliminary results suggested the great promise of kinematics information as well as the biological signals in detecting users conscious effort for robot-aided active rehabilitation.
Related JoVE Video
Using speech for mode selection in control of multifunctional myoelectric prostheses.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 10-11-2013
Show Abstract
Hide Abstract
Electromyogram (EMG) recorded from residual muscles of limbs is considered as suitable control information for motorized prostheses. However, in case of high-level amputations, the residual muscles are usually limited, which may not provide enough EMG for flexible control of myoelectric prostheses with multiple degrees of freedom of movements. Here, we proposed a control strategy, where the speech signals were used as additional information and combined with the EMG signals to realize more flexible control of multifunctional prostheses. By replacing the traditional "sequential mode-switching (joint-switching)", the speech signals were used to select a mode (joint) of the prosthetic arm, and then the EMG signals were applied to determine a motion class involved in the selected joint and to execute the motion. Preliminary results from three able-bodied subjects and one transhumeral amputee demonstrated the proposed strategy could achieve a high mode-selection rate and enhance the operation efficiency, suggesting the strategy may improve the control performance of commercial myoelectric prostheses.
Related JoVE Video
A novel electrochemical biosensor for monitoring protein nitration damage affected by NaNO2/hemin/H2O2.
Biosens Bioelectron
PUBLISHED: 08-28-2013
Show Abstract
Hide Abstract
A sensitive and facile electrochemical biosensor has been developed for monitoring the protein nitration damage affected by the nitro free radicals(NO2). The NO2 radicals is generated from hemin-catalyzed oxidation of nitrite (NO(-)2) in the presence of hydrogen peroxide (H2O2). In this work, nanocomposite films of graphene-gold nanoparticles (EG-AuNPs) were modified on the glassy carbon electrode by electropolymerization. Bovine serum albumin (BSA) was then further assembled on EG-AuNPs film through Au-S bond. The damage of BSA molecule was caused by the NO2 radicals which was generated from the NaNO2/hemin/H2O2 nitration reagent. The differential pulse voltammetry was used to detect the damage of BSA molecule. Fluorescence spectra and circular dichroism spectrum further confirmed the nitration damage of BSA. Moreover, the lowest concentration at which the BSA damage was detected is 28.9µM NO(-)2 or H2O2, and the volume ratio of NO(-)2 and H2O2 was 1:1 in the hemin/NO(-)2/H2O2 nitration reagent. The results demonstrated that the proposed electrochemical method can be used to detect protein damage affected by nitration reagent. The developed electrochemical biosensor is envisioned to have promising applications in protein damage studies.
Related JoVE Video
Knockdown of thioredoxin-interacting protein ameliorates high glucose-induced epithelial to mesenchymal transition in renal tubular epithelial cells.
Cell. Signal.
PUBLISHED: 08-18-2013
Show Abstract
Hide Abstract
Epithelial to mesenchymal transition (EMT) of tubular cells contributes to the renal accumulation of matrix protein that is associated with diabetic nephropathy. Both high glucose and transforming growth factor-? (TGF-?) are able to induce EMT in cell culture. In this study, we examined the role of the thioredoxin-interacting protein (TXNIP) on EMT induced by high glucose or TGF-?1 in HK-2 cells. EMT was assessed by the expression of ?-smooth muscle actin (?-SMA) and E-cadherin and the induction of a myofibroblastic phenotype. High glucose (30mM) was shown to induce EMT at 72h. This was blocked by knockdown of TXNIP or antioxidant NAC. Meanwhile, we also found that knockdown of TXNIP or antioxidant NAC inhibited high glucose-induced generation of reactive oxygen species (ROS), phosphorylation of p38 MAPK and ERK1/2 and expression of TGF-?1. HK-2 cells that were exposed to TGF-?1 (4ng/ml) also underwent EMT. The expression of TXNIP gene and protein was increased in HK-2 cells treated with TGF-?1. Transfection with TXNIP shRNA was able to attenuate TGF-?1 induced-EMT. These results suggested that knockdown of TXNIP antagonized high glucose-induced EMT by inhibiting ROS production, activation of p38 MAPK and ERK1/2, and expression of TGF-?1, highlighting TXNIP as a potential therapy target for diabetic nephropathy.
Related JoVE Video
Identification of 4?-isovaleryl-spiramycin III produced by Bacillus sp. fmbJ.
Arch. Microbiol.
PUBLISHED: 07-18-2013
Show Abstract
Hide Abstract
The production of secondary metabolites with antibiotic properties is a common characteristic to Bacillus spp. These metabolites not only have diverse chemical structures but also have a wide range of bioactivities with medicinal and agricultural interests such as antibiotic. Bacillus sp. fmbJ has been found to produce lipopeptides fengycin and surfactin in accordance with our previous report. In this study, another antimicrobial substance was separated and purified from the culture supernatant of strain fmbJ using the silica gel column chromatography and preparative reversed-phase high-performance liquid chromatography. By means of electrospray ionization mass spectroscopy, infrared spectroscopy, and nuclear magnetic resonance, the antagonistic compound was determined to be 4?-isovaleryl-spiramycin III with the molecular weight of 982 Da. This report is the first to introduce the finding of spiramycin produced from Bacillus sp. The study provides a novel source for the production of spiramycin in pharmaceutical industries.
Related JoVE Video
Effect of silver nanoparticles and antibiotics on antibiotic resistance genes in anaerobic digestion.
Water Environ. Res.
PUBLISHED: 06-25-2013
Show Abstract
Hide Abstract
Water resource recovery facilities have been described as creating breeding ground conditions for the selection, transfer, and dissemination of antibiotic resistance genes (ARGs) among various bacteria. The objective of this study was to determine the effect of direct addition of antibiotic and silver nanoparticles (Ag NPs, or nanosilver) on the occurrence of ARGs in thermophilic anaerobic digesters. Test thermophilic digesters were amended with environmentally-relevant concentrations of Ag NP (0.01, 0.1, and 1.0 mg-Ag/L; corresponding to approximately 0.7, 7.0, and 70 mg-Ag/kg total solids) and sulfamethoxazole (SMX) that span susceptible to resistant classifications (1, 5, and 50 mg/L) as potential selection pressures for ARGs. Tetracycline (tet(O), tet(W)) and sulfonamide (sulI, sulII) ARGs and the integrase enzyme gene (intI1) associated with Class 1 integrons were measured in raw sludge, test thermophilic digesters, a control thermophilic digester, and a control mesophilic digester. There was no apparent effect of Ag NPs on thermophilic anaerobic digester performance. The maximum SMX addition (50 mg/L) resulted in accumulation of volatile fatty acids and low pH, alkalinity, and volatile solids reduction. There was no significant difference between ARG gene copy numbers (absolute or normalized to 16S rRNA genes) in amended thermophilic digesters and the control thermophilic digester. Antibiotic resistance gene copy numbers in digested sludge ranged from 10(3) to 10(6) copies per microL (approximately 8 x10(1) to 8 x 10(4) copies per microg) of sludge as result of a 1-log reduction of ARGs (2-log reduction for intI1). Quantities of the five ARGs in raw sludge ranged from 10(4) to 10(8) copies per microL (approximately 4 x 10(2) to 4 x 10(6) per microg) of sludge. Test and control thermophilic digesters (53 degrees C, 12-day solids retention time [SRT]) consistently reduced but did not eliminate levels of all analyzed genes. The mesophilic digester (37 degrees C, 20-day SRT) also reduced levels of sulI, sulII, and intI1 genes, but levels of tet(O) and tet(W) were the same or higher than in raw sludge. Antibiotic resistance gene reductions remained constant despite the application of selection pressures, which suggests that digester operating conditions are a strong governing factor of the bacterial community composition and thus the prevalence of ARGs.
Related JoVE Video
Magnetically separable Fe3O4@SiO2@TiO2-Ag microspheres with well-designed nanostructure and enhanced photocatalytic activity.
J. Hazard. Mater.
PUBLISHED: 06-19-2013
Show Abstract
Hide Abstract
Major efforts in modern material chemistry are devoted to the design and fabrication of nanostructured systems with tunable physical-chemical properties for advanced catalytic applications. Here, a novel Fe3O4@SiO2@TiO2-Ag nanocomposite has been synthesized and characterized by a series of techniques including SEM, TEM, XRD, XPS as well as magnetization measurement and subsequently tested for the photocatalytic activities. The well-designed nanocomposite exhibits significantly superior activity to that of the commercial Degussa P25 thanks to the suppression of electron-hole pairs from recombination by Ag nanoparticles, and can be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running 10 times. The unique nanostructure makes Fe3O4@SiO2@TiO2-Ag a highly efficient, recoverable, stable, and cost-effective photocatalytic system offering broad opportunities in the field of catalyst synthesis and application.
Related JoVE Video
Efficacy of postoperative adjuvant transfusion of cytokine-induced killer cells combined with chemotherapy in patients with colorectal cancer.
Cancer Immunol. Immunother.
PUBLISHED: 06-19-2013
Show Abstract
Hide Abstract
To assess the activity and safety of postoperative adjuvant immunotherapy with transfusion of cytokine-induced killer (CIK) cells combined with chemotherapy in patients with colorectal cancer.
Related JoVE Video
Structural and mechanistic bases of the anticancer activity of natural aporphinoid alkaloids.
Curr Top Med Chem
PUBLISHED: 06-06-2013
Show Abstract
Hide Abstract
Aporphinoid alkaloids, which encompass a large number of complicated structures, are an important group of natural products. The anticancer activity of aporphinoid alkaloids has become a hot pharmaceutical research area in recent years. Recent studies on the anticancer activity of these compounds are reviewed. The structure activity relationships (SARs) and anticancer mechanisms of aporphinoid alkaloids, as well as simple aporphine, oxoaporphine, dehydroaporphine and dimeric aporphine, have been summarized. The presence of a 1,2-methylenedioxy group and methylation of nitrogen are key features to the cytotoxicity of aporphinoid alkaloids. Oxidation and dehydrogenation of C7 could improve the anticancer activity. The contributions of chirality of hydrogen at C6a and the substitution pattern of other positions about aporphinoid alkaloids for anticancer activity remain unknown. Induced cancer cells apoptosis, prevention of cell proliferation, DNA topoisomerase inhibition, reducing the drug-resistant cellular side population (SP) or cancer stem cells (CSCs) and inhibition of epidermal growth factor receptor (EGFR) tyrosine kinase seem to play important roles in the molecular mechanisms of anticancer activity about aporphinoid alkaloids.
Related JoVE Video
Viral categorization and discovery in human circulation by transcriptome sequencing.
Biochem. Biophys. Res. Commun.
PUBLISHED: 05-17-2013
Show Abstract
Hide Abstract
Serum is the most common and easily accessible patient specimen in a minimally invasive manner. As a biological resource, RNA in serum has been less explored for its clinical utilization due to prevailing concerns regarding its high degradable nature. In the current study, however, we have documented the use of human serum RNA for viral categorization and discovery through transcriptome sequencing and analysis using well-curated databases and advanced bioinformatic tools. Such an integrated approach may have an immediate application in any clinical situations concerning with viral etiology.
Related JoVE Video
Comprehensive cloning of patient-derived 9022-bp amplicons of hepatitis C virus.
J. Virol. Methods
PUBLISHED: 03-28-2013
Show Abstract
Hide Abstract
The instability of recombinant clones accommodating large or full-length viral genomes is frequently a technical challenge in RNA virus research. In an attempt to establish a rapid plasmid-based reverse genetics system that utilizes long RT-PCR technique (LRP), similar difficulty was encountered in the cloning of 9022-bp LRP amplicon. All HCV genotype 1a strains used for LRP cloning showed a remarkable difference in terms of cloning stability. Subsequent analysis revealed the predictive value of phylogenetic positions in determining the cloning stability. Putative Escherichia coli promoters on the HCV genome might be responsible for such cloning difference. An exhaustive exploration, testing nearly one hundred cloning protocols, did not reveal a general approach that can achieve stable cloning for all HCV 1a strains. The selection of appropriate strains, guided by phylogenetic analysis, appears to be necessary prior to the construction of infectious HCV 1a clones. These observations are not only valuable for potentially establishing an HCV 1a cell culture model but also have general implications for other RNA viruses due to concern about cloning instability.
Related JoVE Video
Purification and characterization of a dehalogenase from Pseudomonas stutzeri DEH130 isolated from the marine sponge Hymeniacidon perlevis.
World J. Microbiol. Biotechnol.
PUBLISHED: 03-25-2013
Show Abstract
Hide Abstract
2-haloacid dehalogenases are enzymes that are capable of degrading 2-haloacid compounds. These enzymes are produced by bacteria, but so far they have only been purified and characterized from terrestrial bacteria. The present study describes the purification and characterization of 2-haloacid dehalogenase from the marine bacterium Pseudomonas stutzeri DEH130. P. Stutzeri DEH130 contained two kinds of 2-haloacid dehalogenase (designated as Dehalogenase I and Dehalogenase II) as detected in the crude cell extract after ammonium sulfate fractionation. Both enzymes appeared to exhibit stereo-specificity with respect to substrate. Dehalogenase I was a 109.9-kDa enzyme that preferentially utilized D-2-chloropropropionate and had optimum activity at pH 7.5. Dehalogenase II, which preferentially utilized L-2-chloropropionate, was further purified by ion-exchange chromatography and gel filtration. Purified Dehalogenase II appeared to be a dimeric enzyme with a subunit of 26.0-kDa. It had maximum activity at pH 10.0 and a temperature of 40 °C. Its activity was not inhibited by DTT and EDTA, but strongly inhibited by Cu²?, Zn²?, and Co²?. The K(m) and V(max) for L-2-chloropropionate were 0.3 mM and 23.8 ?mol/min/mg, respectively. Its substrate specificity was limited to short chain mono-substituted 2-halocarboxylic acids, with no activity detected toward fluoropropionate and monoiodoacetate. This is the first report on the purification and characterization of 2-haloacid dehalogenase from a marine bacterium.
Related JoVE Video
Simultaneous determination of trantinterol and its metabolites in rat urine and feces by liquid chromatography-tandem mass spectrometry.
J. Chromatogr. B Analyt. Technol. Biomed. Life Sci.
PUBLISHED: 03-19-2013
Show Abstract
Hide Abstract
A highly selective and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of trantinterol (SPFF) and its major metabolites for the first time. The analytes were extracted from rat urine and feces samples by liquid-liquid extraction (LLE) and determined in multiple reaction monitoring (MRM) mode with clenbuterol as the internal standard. Chromatographic separation was achieved on a Venusil ASB C8 column (2.1mm×100mm, 3?m), with the mobile phase consisted of methanol-0.2% formic acid (30:70, v/v) at the flow rate of 0.2mL/min. Each sample was chromatographed within 5min. This method has a lower limit of quantification (LLOQ) of 0.450, 1.05, 1.35, 0.904 and 1.36ng/mL for trantinterol (SPFF), arylhydroxylamine trantinterol (N-OH-SPFF), tert-butyl hydroxylated trantinterol (Tert-OH-SPFF), 1-carbonyl trantinterol (SPFF-COOH) and 3-methyl sulfone-dechloro-trantinterol (SPFF-SO2CH3) in rat urine, and 0.450, 1.35 and 0.904ng/mL for SPFF, Tert-OH-SPFF and SPFF-COOH in rat feces, respectively. The linear correlation coefficients were greater than 0.990. The intra- and inter-day precision (relative standard deviation, RSD) values were below 15% and the accuracy (relative error, RE) was -9.9% to 11% at three quality control levels. The method has been successfully applied to the excretion study following an oral administration of 1mg/kg trantinterol to rats.
Related JoVE Video
Proteomics reveal cucumber Spd-responses under normal condition and salt stress.
Plant Physiol. Biochem.
PUBLISHED: 02-21-2013
Show Abstract
Hide Abstract
To investigate the effects of exogenous Spd on proteomic changes under normal condition and NaCl stress of 3 days in cucumber seedling leaves, a 2-DE gel electrophoresis and MALDI-TOF/TOF MS was performed. A total of 63 differentially expressed proteins responded to salt stress or exogenous Spd treatments, and they were all successfully identified by MALDI-TOF/TOF MS. Many changes were observed in the levels of proteins involved in energy and metabolic pathways, protein metabolic, stress defense, and other functional proteins. Increased salt tolerance by exogenous Spd would contribute to higher expressions of proteins involved in the SAMs metabolism, protein biosynthesis, and defense mechanisms on antioxidant and detoxification. Meanwhile, the regulation of Calvin cycle, protein folding assembly and the inhibition of protein proteolysis by Spd might play important roles in salt tolerance. This study provides insight that may facilitate a better understanding of the salt resistance by Spd in cucumber seedlings.
Related JoVE Video
Pressurized liquid extraction coupled with countercurrent chromatography for systematic isolation of chemical constituents by preprogrammed automatic control.
J. Chromatogr. B Analyt. Technol. Biomed. Life Sci.
PUBLISHED: 02-20-2013
Show Abstract
Hide Abstract
Pressurized liquid extraction (PLE) coupled with high-speed countercurrent chromatography (HSCCC) via an automated procedure was firstly developed to extract and isolate ginsenosides from Panax quinquefolium. The experiments were designed under the guidance of mathematical model. The partition coefficient (K) values of the target compounds and resolutions of peak profiles were employed as the research indicators, and exponential function and binomial formulas were used to optimizing the solvent systems and flow rates of the mobile phases in a three-stage separation. In the first stage, ethyl acetate, n-butanol, and water were simultaneously pumped into the solvent separator at the flow rates 11.0, 10.0, and 23.0mL/min, respectively. The upper phase of the solvent system in the solvent separator was used as both the PLE solvent and the HSCCC stationary phase, followed by elution with the lower phase of the corresponding solvent system to separate the common ginsenosides. In the second and third stages, rare ginsenosides were first separated by elution with ethyl acetate, n-butanol, methanol, and water (flow rates: 20.0, 3.0, 5.0, and 11.0mL/min, respectively), then with n-heptane, n-butanol, methanol, and water (flow rates: 17.5, 6.0, 5.0, and 22.5mL/min, respectively). Nine target compounds, with purities exceeding 95.0%, and three non-target compounds, with purities above 84.48%, were successfully separated at the semipreparative scale in 450min. The separation results prove that the PLE/HSCCC parameters calculated via mathematical model and formulas were accurately and scientifically. This research has opened up great prospects for industrial automation application.
Related JoVE Video
Engineering the nanoarchitecture and texture of polymeric carbon nitride semiconductor for enhanced visible light photocatalytic activity.
J Colloid Interface Sci
PUBLISHED: 02-20-2013
Show Abstract
Hide Abstract
In order to develop g-C3N4 for better visible light photocatalysis, g-C3N4 nanoarchitectures was synthesized by direct pyrolysis of cheap urea at 550°C and engineered through the variation of pyrolysis time. By prolonging the pyrolysis time, the crystallinity of the resulted sample was enhanced, the thickness and size of the layers were reduced, the surface area and pore volume were significantly enlarged, and the band structure was modified. Especially for urea treated for 4h, the obtained g-C3N4 nanosheets possessed high surface area (288 m(2)/g) due to the reduced layer thickness and the improved porous structure. A layer exfoliation and splitting mechanism was proposed to explain the gradual reduction of layer thickness and size of g-C3N4 nanoarchitectures with increased pyrolysis time. The as-synthesized g-C3N4 samples were applied for photocatalytic removal of gaseous NO and aqueous RhB under visible light irradiation. It was found that the activity of g-C3N4 was gradually improved as the pyrolysis time was prolonged from 0 min to 240 min. The enhanced crystallinity, reduced layer thickness, high surface area, large pore volume, enlarged band gap, and reduced number of defects were responsible for the activity enhancement of g-C3N4 sample treated for a longer time. As the precursor urea is very cheap and the synthesis method is facile template-free, the as-synthesized g-C3N4 nanoscale sheets could provide an efficient visible light driven photocatalyst for large-scale applications.
Related JoVE Video
Bottle gourd rootstock-grafting affects nitrogen metabolism in NaCl-stressed watermelon leaves and enhances short-term salt tolerance.
J. Plant Physiol.
PUBLISHED: 02-09-2013
Show Abstract
Hide Abstract
The plant growth, nitrogen absorption, and assimilation in watermelon (Citrullus lanatus [Thunb.] Mansf.) were investigated in self-grafted and grafted seedlings using the salt-tolerant bottle gourd rootstock Chaofeng Kangshengwang (Lagenaria siceraria Standl.) exposed to 100mM NaCl for 3d. The biomass and NO3(-) uptake rate were significantly increased by rootstock while these values were remarkably decreased by salt stress. However, compared with self-grafted plants, rootstock-grafted plants showed higher salt tolerance with higher biomass and NO3(-) uptake rate under salt stress. Salinity induced strong accumulation of nitrate, ammonium and protein contents and a significant decrease of nitrogen content and the activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) in leaves of self-grafted seedlings. In contrast, salt stress caused a remarkable decrease in nitrate content and the activities of GS and GOGAT, and a significant increase of ammonium, protein, and nitrogen contents and NR activity, in leaves of rootstock-grafted seedlings. Compared with that of self-grafted seedlings, the ammonium content in leaves of rootstock-grafted seedlings was much lower under salt stress. Glutamate dehydrogenase (GDH) activity was notably enhanced in leaves of rootstock-grafted seedlings, whereas it was significantly inhibited in leaves of self-grafted seedlings, under salinity stress. Three GDH isozymes were isolated by native gel electrophoresis and their expressions were greatly enhanced in leaves of rootstock-grafted seedlings than those of self-grafted seedlings under both normal and salt-stress conditions. These results indicated that the salt tolerance of rootstock-grafted seedlings might (be enhanced) owing to the higher nitrogen absorption and the higher activities of enzymes for nitrogen assimilation induced by the rootstock. Furthermore, the detoxification of ammonium by GDH when the GS/GOGAT pathway was inhibited under salt stress might play an important role in the release of salt stress in rootstock-grafted seedlings.
Related JoVE Video
Interleukin-6 primarily produced by non-hematopoietic cells mediates the lipopolysaccharide-induced febrile response.
Brain Behav. Immun.
PUBLISHED: 01-31-2013
Show Abstract
Hide Abstract
Interleukin-6 (IL-6) is critical for the lipopolysaccharide (LPS)-induced febrile response. However, the exact source(s) of IL-6 involved in regulating the LPS-elicited fever is still to be identified. One known source of IL-6 is hematopoietic cells, such as monocytes. To clarify the contribution of hematopoietically derived IL-6 to fever, we created chimeric mice expressing IL-6 selectively either in cells of hematopoietic or, conversely, in cells of non-hematopoietic origin. This was performed by extinguishing hematopoietic cells in wild-type (WT) or IL-6 knockout (IL-6 KO) mice by whole-body irradiation and transplanting them with new stem cells. Mice on a WT background but lacking IL-6 in hematopoietic cells displayed normal fever to LPS and were found to have similar levels of IL-6 protein in the cerebrospinal fluid (CSF) and in plasma and of IL-6 mRNA in the brain as WT mice. In contrast, mice on an IL-6 KO background, but with intact IL-6 production in cells of hematopoietic origin, only showed a minor elevation of the body temperature after peripheral LPS injection. While they displayed significantly elevated levels of IL-6 both in plasma and CSF compared with control mice, the increase was modest compared with that seen in LPS injected mice on a WT background, the latter being approximately 20 times larger in magnitude. These results suggest that IL-6 of non-hematopoietic origin is the main source of IL-6 in LPS-induced fever, and that IL-6 produced by hematopoietic cells only plays a minor role.
Related JoVE Video
Quantitative synthesis of the association between the cytochrome P450 1A1 Ile462Val polymorphism and prostate cancer risk.
Tumour Biol.
PUBLISHED: 01-21-2013
Show Abstract
Hide Abstract
The association between the cytochrome P450 1A1 (CYP1A1) Ile462Val polymorphism and prostate cancer risk remains inconclusive owing to the conflicting findings from previous studies. To get a more precise estimate of the possible association, we performed the present meta-analysis. We searched the PUBMED, EMBASE, and Wanfang databases for the studies which met the inclusion criteria. The pooled odds ratio (OR) with corresponding 95 % confidence interval (95 % CI) was used to estimate the association between CYP1A1 Ile462Val polymorphism and prostate cancer risk. A total of 13 studies with 2,350 cases and 2,992 controls were included in the meta-analysis. The results indicated that there was an obvious association between CYP1A1 Ile462Val polymorphism and increased risk of prostate cancer (for Val versus Ile: OR=1.27, 95 % CI 1.13-1.43, P<0.001; for ValVal versus IleIle: OR=1.51, 95 % CI 1.14-2.01, P=0.004; for ValVal?+?ValIle versus IleIle: OR=1.31, 95 % CI 1.14-1.51, P<0.001; for ValVal versus IleIle + ValIle: OR=1.38, 95 % CI 1.05-1.81, P=0.020). Subgroup analyses by ethnicity suggested that CYP1A1 Ile462Val polymorphism was associated with prostate cancer risk in Asians but not in Caucasians. This meta-analysis suggests that there is an association between CYP1A1 Ile462Val polymorphism and increased risk of prostate cancer. More studies with large sample are needed to further assess the association in Caucasians.
Related JoVE Video
Glutathione S-transferase P1 Ile105Val polymorphism contributes to increased risk of gastric cancer in East Asians.
Tumour Biol.
PUBLISHED: 01-17-2013
Show Abstract
Hide Abstract
Glutathione S-transferase P1 (GSTP1) is an important enzyme playing critical roles in the phase II detoxification pathway. There were many studies investigating the association between GSTP1 gene Ile105Val polymorphism and gastric cancer risk, but studies from East Asians reported inconsistent findings. We performed a meta-analysis to investigate the association in East Asians. Published literature from PubMed and Chinese Biomedical Literature databases were searched for eligible publications. Pooled odds ratios (ORs) with 95 % confidence intervals (95 %CIs) were calculated using random or fixed-effect model according the between-study heterogeneity. A total of 12 studies with 2,552 cases and 5,474 controls were finally included into the meta-analysis. Meta-analysis of those 12 studies showed that there was an obvious association between GSTP1 Ile105Val polymorphism and gastric cancer risk in East Asians under three genetic models (for valine vs. isoleucine, OR=1.32, 95 %CI 1.05-1.66, P=0.015; for ValVal vs. IleIle, OR=2.00, 95 %CI 1.34-2.98, P=0.001; for the recessive model, OR=1.96, 95 %CI 1.35-2.83, P<0.001). Sensitivity analysis by removing one study at a time suggested the pooled results were stable under the three genetic models above. There was no risk of publication bias. In conclusion, the meta-analysis suggests that there is a strong evidence for the association between GSTP1 Ile105Val polymorphism and increased risk of gastric cancer in East Asians and contributes to increased risk of gastric cancer in East Asians.
Related JoVE Video
Primary analysis of the expressed sequence tags in a pentastomid nymph cDNA library.
PLoS ONE
PUBLISHED: 01-10-2013
Show Abstract
Hide Abstract
Pentastomiasis is a rare zoonotic disease caused by pentastomids. Despite their worm-like appearance, they are commonly placed into a separate sub-class of the subphylum Crustacea, phylum Arthropoda. However, until now, the systematic classification of the pentastomids and the diagnosis of pentastomiasis are immature, and genetic information about pentastomid nylum is almost nonexistent. The objective of this study was to obtain information on pentastomid nymph genes and identify the gene homologues related to host-parasite interactions or stage-specific antigens.
Related JoVE Video
Microbial products induce claudin-2 to compromise gut epithelial barrier function.
PLoS ONE
PUBLISHED: 01-01-2013
Show Abstract
Hide Abstract
The epithelial barrier dysfunction is an important pathogenic feature in a number of diseases. The underlying mechanism is to be further investigated. The present study aims to investigate the role of tight junction protein claudin-2 (Cldn2) in the compromising epithelial barrier function. In this study, the expression of Cldn2 in the epithelial layer of mice and patients with food allergy was observed by immunohistochemistry. The induction of Cldn2 was carried out with a cell culture model. The Cldn2-facilitated antigen internalization was observed by confocal microscopy. The epithelial barrier function in the gut epithelial monolayer was assessed by recording the transepithelial resistance and assessing the permeability to a macromolecular tracer. The results showed that the positive immune staining of Cldn2 was observed in the epithelial layer of the small intestine that was weakly stained in naïve control mice, and strongly stained in sensitized mice as well as patients with food allergy. Exposure to cholera toxin or Staphylococcal enterotoxin B induced the expression of Cldn2 in HT-29 or T84 cells. Cldn2 could bind protein antigen to form complexes to facilitate the antigen transport across the epithelial barrier. Blocking Cldn2 prevented the allergen-related hypersensitivity the intestine. We conclude that the tight junction protein Cldn2 is involved in the epithelial barrier dysfunction.
Related JoVE Video
Transcriptome characteristics and six alternative expressed genes positively correlated with the phase transition of annual cambial activities in Chinese Fir (Cunninghamia lanceolata (Lamb.) Hook).
PLoS ONE
PUBLISHED: 01-01-2013
Show Abstract
Hide Abstract
The molecular mechanisms that govern cambial activity in angiosperms are well established, but little is known about these molecular mechanisms in gymnosperms. Chinese fir (Cunninghamia lanceolata (Lamb.) Hook), a diploid (2n ?=?2x ?=?22) gymnosperm, is one of the most important industrial and commercial timber species in China. Here, we performed transcriptome sequencing to identify the repertoire of genes expressed in cambium tissue of Chinese fir.
Related JoVE Video
Metal-free activation of H2O2 by g-C3N4 under visible light irradiation for the degradation of organic pollutants.
Phys Chem Chem Phys
PUBLISHED: 12-09-2011
Show Abstract
Hide Abstract
Semiconducting carbon nitride materials were successfully prepared via a thermal poly-condensation of dicyandiamide as a precursor at >500 °C. The resulting materials were investigated as metal-free catalysts for the activation of H(2)O(2) with visible light under mild conditions, using the decomposition of Rhodamine B (RhB) in aqueous solution as a model reaction. Results revealed that carbon nitride catalysts can activate H(2)O(2) to generate reactive oxy-radicals under visible light irradiation without employment of any metal additives, leading to the mineralization of the dye. Factors affecting the degradation of organic compounds are pH values and the concentration of H(2)O(2). Recycling of the catalyst indicated no obvious deactivation during the entire catalytic reaction, indicating good (photo)chemical stability of metal-free polymeric carbon nitride photocatalysts for environmental purification. This study demonstrated a promising approach for the activation of green oxidant, hydrogen peroxide, by the newly-developed polymer photocatalysts for environmental remediation and oxidation catalysis.
Related JoVE Video
Novel in situ N-doped (BiO)2CO3 hierarchical microspheres self-assembled by nanosheets as efficient and durable visible light driven photocatalyst.
Langmuir
PUBLISHED: 12-09-2011
Show Abstract
Hide Abstract
Novel N-doped (BiO)(2)CO(3) hierarchical microspheres (N-BOC) were fabricated by a facile one-pot template free method on the basis of hydrothermal treatment of bismuth citrate and urea in water for the first time. The N-BOC sample was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, N(2) adsorption-desorption isotherms, and Fourier transform-infrared spectroscopy. The N-BOC was constructed by the self-assembly of single-crystalline nanosheets. The aggregation of nanosheets led to the formation of hierarchical framework with mesopores, which is favorable for efficient transport of reaction molecules and harvesting of photoenergy. Due to the in situ doped nitrogen substituting for oxygen in the lattice of (BiO)(2)CO(3), the band gap of N-BOC was reduced from 3.4 to 2.5 eV, making N-BOC visible light active. The N-BOC exhibited not only excellent visible light photocatalytic activity, but also high photochemical stability and durability during repeated and long-term photocatalytic removal of NO in air due to the special hierarchical structure. This work demonstrates that the facile fabrication method for N-BOC combined with the associated outstanding visible light photocatalytic performance could provide new insights into the morphology-controlled fabrication of nanostructured photocatalytic materials for environmental pollution control.
Related JoVE Video
Emergence of NK-cell progenitors and functionally competent NK-cell lineage subsets in the early mouse embryo.
Blood
PUBLISHED: 11-09-2011
Show Abstract
Hide Abstract
The earliest stages of natural killer (NK)-cell development are not well characterized. In this study, we investigated in different fetal hematopoietic tissues how NK-cell progenitors and their mature NK-cell progeny emerge and expand during fetal development. Here we demonstrate, for the first time, that the counterpart of adult BM Lin(-)CD122(+)NK1.1(-)DX5(-) NK-cell progenitor (NKP) emerges in the fetal liver at E13.5. After NKP expansion, immature NK cells emerge at E14.5 in the liver and E15.5 in the spleen. Thymic NK cells arise at E15.5, whereas functionally competent cytotoxic NK cells were present in the liver and spleen at E16.5 and E17.5, respectively. Fetal NKPs failed to produce B and myeloid cells but sustained combined NK- and T-lineage potential at the single-cell level. NKPs were also found in the fetal blood, spleen, and thymus. These findings show the emergence and expansion of bipotent NK/T-cell progenitor during fetal and adult lymphopoiesis, further supporting that NK/T-lineage restriction is taking place prethymically. Uncovering the earliest NK-cell developmental stages will provide important clues, helping to understand the origin of diverse NK-cell subsets, their progenitors, and key regulators.
Related JoVE Video
Performance of electromyography recorded using textile electrodes in classifying arm movements.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 08-29-2011
Show Abstract
Hide Abstract
Electromyography (EMG) signals are commonly recorded using the Ag/AgCl gel electrodes in myoelectric prosthetic control. While a gelled electrode may provide high-quality EMG recordings, it is inconvenient in clinical application of a myoelectric prosthesis. A novel type of signal sensors-textile electrodes should be ideal in control of myoelectric prostheses. However, it is unknown whether the performance of textile electrodes is comparable to commonly used electrodes in classifying arm movements. In this study, the custom-made bipolar textile electrodes were fabricated using copper-based nickel-plated conductive fabric and were used to record EMG signals. The performance of EMG signals recorded with textile electrodes in identifying nine arm and hand movements were investigated. Our pilot results showed that the average classification accuracy across six able-bodied subjects was 94.05% when using textile electrodes and 94.26% when using conventional electrodes, with no significant difference between the two types of electrodes (p=0.81). The pilot results suggest that the textile electrodes could achieve similar performance in classifying arm movements in control of myoelectric prostheses as the gelled metal electrodes.
Related JoVE Video
Divergent quasispecies evolution in de novo hepatitis C virus infection associated with bone marrow transplantation.
Biochem. Biophys. Res. Commun.
PUBLISHED: 08-26-2011
Show Abstract
Hide Abstract
Quasispecies is a remarkable characteristic of hepatitis C virus (HCV) and has profound roles in HCV biology and clinical practice. The understanding of HCV quasispecies behavior, in particular in acute HCV infection, is valuable for vaccine development and therapeutic interference. However, acute HCV infection is seldom encountered in clinic practice due to its silent onset. In the present study, we reported a unique case of de novo HCV infection associated with the transplantation of bone marrow from a HCV-positive donor. HCV quasispecies diversity was determined in both the donor and the recipient over a 4-year follow-up, accompanied with simultaneous measurement of HCV neutralizing antibody. Detailed genetic and phylogenetic analyses revealed a divergent quasispecies evolution, which was not related to dynamic changes of HCV neutralizing antibody. Instead, our data suggested an essential role of the fitness adaptation of founder viral population in driving such an evolutionary pattern.
Related JoVE Video
Identification of hypoxic-responsive proteins in cucumber roots using a proteomic approach.
Plant Physiol. Biochem.
PUBLISHED: 08-24-2011
Show Abstract
Hide Abstract
To elaborate the mechanisms of response of cucumber (Cucumis sativus L. cv.) seedlings to hypoxic stress, plants were grown under either normoxic conditions or hypoxic stress. As expected, plant biomass was significantly reduced under hypoxic stress. Proteomic profiles of cucumber roots were studied at 72 h after treatment; 316 and 425 protein spots were detected on polyacrylamide gels from normoxic and hypoxic-treated plants, respectively. Compared with normoxic-treated plants, protein abundance of 22 proteins was significantly upregulated while protein abundance of 12 proteins decreased in the hypoxic-treated plants. Twenty one of the proteins whose abundance was altered were identified by MALDI-TOF/TOF MS analysis, and categorized into classes corresponding to energy and metabolism proteins, transcription factor proteins, defense stress proteins, structural proteins and regulatory proteins. Under hypoxic stress, glycolysis was induced; energy was channeled to primary metabolism, while secondary pathways and nitrogen metabolism pathways were inhibited. Cucumber plants scavenged reactive oxygen species by antioxidase, and increased Acyl-[acyl-carrier-protein] desaturase which defend against reactive oxygen species damage to plant cell structure. This study provides insight that may facilitate a better understanding of the response mechanisms of cucumber plant to hypoxic stress.
Related JoVE Video
The Core/E1 domain of hepatitis C virus genotype 4a in Egypt does not contain viral mutations or strains specific for hepatocellular carcinoma.
J. Clin. Virol.
PUBLISHED: 04-21-2011
Show Abstract
Hide Abstract
Hepatitis C virus (HCV) infection is a well-documented etiological factor for hepatocellular carcinoma (HCC). As HCV shows remarkable genetic diversity, an interesting and important issue is whether such a high viral genetic diversity plays a role in the incidence of HCC. Prior data on this subject are conflicting.
Related JoVE Video
Headspace solid-phase microextraction with on-fiber derivatization for the determination of aldehydes in algae by gas chromatography-mass spectrometry.
J Sep Sci
PUBLISHED: 03-20-2011
Show Abstract
Hide Abstract
A simple, fast, sensitive and cost-effective method based on headspace solid-phase microextraction (HS-SPME) with on-fiber derivatization coupled with gas chromatography-mass spectrometry was developed for the determination of six typical aldehydes, 2E-hexenal, heptanal, 2E-heptenal, 2E,4E-heptadienal, 2E-decenal and 2E,4E-decadienal in laboratory algae cultures. As derivatization reagent, O-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride, was loaded onto the poly(dimethylsiloxane)/divinylbenzene fiber for aldehydes on-fiber derivatization prior to HS-SPME. Various influence factors of extraction efficiency were systematically investigated. Under optimized extraction conditions, excellent method performances for all the six aldehydes were attained, such as satisfactory extraction recoveries ranging from 67.1 to 117%, with the precision (relative standard deviation) within 5.3-11.1%, and low detection limits in the range of 0.026-0.044 ?g/L. The validated method was successfully applied for the analysis of the aldehydes in two diatoms (Skeletonema costatum and Chaetoceros muelleri), two pyrrophytas (Prorocentrum micans and Scrippsiella trochoidea) and Calanus sinicus eggs (feeding on the two diatoms above).
Related JoVE Video
Isolation, characterization and identification of a Paracoccus sp. 2-haloacid-degrading bacterium from the marine sponge Hymeniacidon perlevis.
J. Basic Microbiol.
PUBLISHED: 02-07-2011
Show Abstract
Hide Abstract
A 2-haloacid dehalogenase-producing bacterium, designated DEH99, was isolated from the marine sponge Hymeniacidon perlevis using a modified enrichment medium and a pH indicator method. DEH99 could degrade only half of the racemic mixture 2-chloropropionic acid (2-CPA) in the medium. The dehalogenase of DEH99 was further determined to be a (S)-2-haloacid dehalogenase, which can degrade 2-CPA, 2-bromopropionic acid (2-BPA), and iodoacetic acid. The gene encoding the (S)-2-haloacid dehalogenase was partially sequenced and classified into the Group II family. The 2-haloacid dehalogenase showed the highest sequence similarity (77% with 21% query coverage) to the haloacid dehalogenase (dhlB) gene of Xanthobacter autotrophicus. A phylogenetic analysis of the 16S rDNA sequence demonstrated that the isolate DEH99 is a member of the genus Paracoccus. To our knowledge, this is the first report detailing the isolation of a strain of genus Paracoccus having 2-haloacid dehalogenase activity from marine sponges.
Related JoVE Video
Microscopic structure and properties changes of cassava stillage residue pretreated by mechanical activation.
Bioresour. Technol.
PUBLISHED: 01-27-2011
Show Abstract
Hide Abstract
This study has focused on the pretreatment of cassava stillage residue (CSR) by mechanical activation (MA) using a self-designed stirring ball mill. The changes in surface morphology, functional groups and crystalline structure of pretreated CSR were examined by using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) under reasonable conditions. The results showed that MA could significantly damage the crystal structure of CSR, resulting in the variation of surface morphology, the increase of amorphous region ratio and hydrogen bond energy, and the decrease in crystallinity and crystalline size. But no new functional groups generated during milling, and the crystal type of cellulose in CSR still belonged to cellulose I after MA.
Related JoVE Video
Conditioning and sampling issues of EMG signals in motion recognition of multifunctional myoelectric prostheses.
Ann Biomed Eng
PUBLISHED: 01-27-2011
Show Abstract
Hide Abstract
Historically, the investigations of electromyography (EMG) pattern recognition-based classification of intentional movements for control of multifunctional prostheses have adopted the filter cut-off frequency and sampling rate that are commonly used in EMG research fields. In practical implementation of a multifunctional prosthesis control, it is desired to have a higher high-pass cut-off frequency to reduce more motion artifacts and to use a lower sampling rate to save the data processing time and memory of the prosthesis controller. However, it remains unclear whether a high high-pass cut-off frequency and a low-sampling rate still preserve sufficient neural control information for accurate classification of movements. In this study, we investigated the effects of high-pass cut-off frequency and sampling rate on accuracy in identifying 11 classes of arm and hand movements in both able-bodied subjects and arm amputees. Compared to a 5-Hz high-pass cut-off frequency, excluding the EMG components below 60 Hz decreased the average accuracy of 0.1% in classifying the 11 movements across able-bodied subjects and increased the average accuracy of 0.1 and 0.4% among the transradial (TR) and shoulder disarticulation (SD) amputees, respectively. Using a 500 Hz instead of a 1-kHz sampling rate, the average classification accuracy only dropped about 2.0% in arm amputees. The combination of sampling rate and high-pass cut-off frequency of 500 and 60 Hz only resulted in about 2.3% decrease in average accuracy for TR amputees and 0.4% decrease for SD amputees in comparison to the generally used values of 1 kHz and 5 Hz. These results suggest that the combination of sampling rate of 500 Hz and high-pass cut-off frequency of 60 Hz should be an optimal selection in EMG recordings for recognition of different arm movements without sacrificing too much of classification accuracy which can also remove most of motion artifacts and power-line interferences for improving the performance of myoelectric prosthesis control.
Related JoVE Video
WRKY22 transcription factor mediates dark-induced leaf senescence in Arabidopsis.
Mol. Cells
PUBLISHED: 01-21-2011
Show Abstract
Hide Abstract
Arabidopsis WRKY proteins are plant-specific transcription factors, encoded by a large gene family, which contain the highly conserved amino acid sequence WRKYGQK and the zinc-finger-like motifs, Cys(2)His(2) or Cys(2)HisCys. They can recognize and bind the TTGAC(C/T) W-box ciselements found in the promoters of target genes, and are involved in the regulation of gene expression during pathogen defense, wounding, trichome development, and senescence. Here we investigated the physiological function of the Arabidopsis WRKY22 transcription factor during dark-induced senescence. WRKY22 transcription was suppressed by light and promoted by darkness. In addition, AtWRKY22 expression was markedly induced by H(2)O(2). These results indicated that AtWRKY22 was involved in signal pathways in response to abiotic stress. Dark-treated AtWRKY22 over-expression and knockout lines showed accelerated and delayed senescence phenotypes, respectively, and senescence-associated genes exhibited increased and decreased expression levels. Mutual regulation existed between AtWRKY22 and AtWRKY6, AtWRKY53, and AtWRKY70, respectively. Moreover, AtWRKY22 could influence their relative expression levels by feedback regulation or by other, as yet unknown mechanisms in response to dark. These results prove that AtWRKY22 participates in the dark-induced senescence signal transduction pathway.
Related JoVE Video
Application of accelerated solvent extraction coupled with high-performance counter-current chromatography to extraction and online isolation of chemical constituents from Hypericum perforatum L.
J Chromatogr A
PUBLISHED: 01-01-2011
Show Abstract
Hide Abstract
Accelerated solvent extraction (ASE) coupled with high-performance counter-current chromatography (HPCCC) was successfully used for the extraction and online isolation of five chemical constituents from the plant Hypericum perforatum L. The upper phase of the solvent system of ethyl acetate-methanol-water (5:2:5, v:v:v) was used as both the ASE solvent and the HPCCC stationary phase. Two hydrophobic compounds including 28.4 mg of hyperforin with a HPLC purity of 97.28% and 32.7 mg of adhyperforin with a HPLC purity of 97.81% were isolated. The lower phase of ethyl acetate-methanol-n-butanol-water (5:2:2.5:12, v:v:v:v) was used as both the ASE solvent and CCC stationary phase. Three hydrophilic compounds of 12.7 mg of 3,4,5-O-tricaffeoylquinic acid with a HPLC purity of 98.82%, 15.2 mg of 1,3,5-O-tricaffeoylquinic acid with a HPLC purity of 99.46% and 42.5mg of 3-O-caffeoylquinic acid with a HPLC purity of 96.90%, were obtained in a one-step extraction-separation process with less than 3h from 10.02 g of raw material of H. perforatum. The targeted compounds isolated, collected and purified by HPCCC were analyzed by high performance liquid chromatography (HPLC), the chemical structures of all five compounds above mentioned were identified by UV, MS and NMR.
Related JoVE Video
Construction of WCB-11: a novel phiYFP arsenic-resistant whole-cell biosensor.
J Environ Sci (China)
PUBLISHED: 12-24-2010
Show Abstract
Hide Abstract
The prediction and assessment of environmental pollution by arsenic are important preconditions of advocating environmental protection and human health risk assessment. A yellow fluorescent protein-based whole-cell biosensor for the detection of arsenite and arsenate was constructed and tested. An arsenic-resistant promoter and the regulatory gene arsR were obtained by PCR from the genome of Escherichia coli DH5alpha, and phiYFP was introduced into E. coli DH5alpha as a reporter gene to construct an arsenic-resistant whole-cell biosensor (WCB-11) in which phiYFP was expressed well for the first time. Experimental results demonstrated that the biosensor has a good response to arsenic and the expression of phiYFP. When strain WCB-11 was exposed to As3+ and As5+, the expression of yellow fluorescence was time-dependent and dose-dependent. This engineered construct is expected to become established as an inexpensive and convenient method for the detection of arsenic in the field.
Related JoVE Video
Selection of sampling rate for EMG pattern recognition based prosthesis control.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 11-25-2010
Show Abstract
Hide Abstract
Most previous studies of electromyography (EMG) pattern recognition control of multifunctional myoelectric prostheses adopted a conventional sampling rate that is commonly used in EMG research fields. However, it is unknown whether using a lower sampling rate in EMG acquisition still preserves sufficient neural control information for accurate classification of user movement intents. This study investigated the effects of EMG sampling rate on the performance of EMG pattern recognition in identifying 11 classes of arm and hand movements. Our results showed that decreasing the sampling rate from 1 kHz to 500 Hz only caused 0.8% reduction of the average classification accuracy over five able-bodied subjects and 2.2% decrease over two transradial amputees. When using a 400 Hz sampling rate, the average classification accuracy decreased 1.3% and 2.8% in able-bodied subjects and amputees, respectively. These results suggest that a sampling rate between 400-500 Hz would be optimal for EMG acquisition in EMG pattern recognition based control of a multifunctional prosthesis.
Related JoVE Video
Pentazocine pretreatment suppresses fentanyl-induced cough.
Pharmacol Rep
PUBLISHED: 10-02-2010
Show Abstract
Hide Abstract
This study evaluated the effect of pentazocine pretreatment on fentanyl-induced cough. With ethics committee approval, 277 ASA I-II patients, aged between 19 and 63 years, undergoing various elective surgeries during general anesthesia, were enrolled in this prospective, randomized, double-blind, placebo-controlled clinical trial. All patients were randomly assigned to one of three groups. Group I (n = 92) and Group II (n = 93) received normal saline, while Group III (n = 92) received pentazocine 0.5 mg·kg(-1) 5 min prior to receiving fentanyl, Patients belonging to Groups II and III were administered 2 ?g/kg fentanyl intravenously over 2 s after the first injection; Group I served as a negative control for fentanyl. Physiologic indicators such as heart rate (HR), non-invasive blood pressure (NBP) and pulse oximetry oxygen saturation (SpO(2)) of patients were recorded before giving pentazocine or normal saline 1 minute after fentanyl injections. The incidence of cough was recorded and graded as mild (1-2), moderate (3-5) and severe (> 5), depending on the number of coughs observed [13]. The incidence of cough was 0%, 22.6% and 4.3% in Group I, Group II and Group III, respectively. There was no significant difference in SpO(2) for the duration of the trial among the three groups. Premedication with intravenous pentazocine can minimize the incidence of fentanyl-induced cough and has no influence on blood pressure, heart rate, and SpO(2) compared with Group II.
Related JoVE Video

What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

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.