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Find video protocols related to scientific articles indexed in Pubmed.
Green facile scalable synthesis of titania/carbon nanocomposites: new use of old dental resins.
ACS Appl Mater Interfaces
PUBLISHED: 10-30-2014
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A green facile scalable method inspired by polymeric dental restorative composite is developed to synthesize TiO2/carbon nanocomposites for manipulation of the intercalation potential of TiO2 as lithium-ion battery anode. Poorly crystallized TiO2 nanoparticles with average sizes of 4-6 nm are homogeneously embedded in carbon matrix with the TiO2 mass content varied between 28 and 65%. Characteristic discharge/charge plateaus of TiO2 are significantly diminished and voltage continues to change along with proceeding discharge/charge process. The tap density, gravimetric and volumetric capacities, and cyclic and rate performance of the TiO2/C composites are effectively improved.
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Enhanced electrochemical performance with surface coating by reactive magnetron sputtering on lithium-rich layered oxide electrodes.
ACS Appl Mater Interfaces
PUBLISHED: 06-09-2014
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Electrode films fabricated with lithium-rich layered 0.3Li2MnO3-0.7LiNi5/21Co5/21Mn11/21O2 cathode materials have been successfully modified with ZnO coatings via a reactive magnetron sputtering (RMS) process for the first time. The morphology and chemical composition of coating films on the electrodes have been in deep investigated by transmission electron microscopy (TEM), energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS) characterizations. The results clearly demonstrate that ZnO film coatings are ultrathin, dense, uniform, and fully covered on the electrodes. The RMS-2 min (deposition time) coated electrode exhibits much higher initial discharge capacity and coulombic efficiency with 316.0 mAh g(-1) and 89.1% than that of the pristine electrode with 283.4 mAh g(-1) and 81.7%. In addition, the discharge capacity also reaches 256.7 and 187.5 mAh g(-1) at 0.1 and 1.0 C-rate, as compared to that of 238.4 and 157.8 mAh g(-1) after 50 cycles. The improved electrochemical performances of RMS-coated electrodes are ascribed to the high-quality ZnO film coatings that reduce charge transfer resistance and effectively protect active material from electrolyte oxidation.
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Regulators of G protein signaling are up-regulated in aspirin-resistant platelets from patients with metabolic syndrome.
Pharmazie
PUBLISHED: 05-27-2014
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G protein-coupled receptor signaling plays a crucial role in platelet function. Regulators of G protein signaling (RGSs), which accelerate the deactivation of G protein signaling, are expressed in platelets. However, RGS expression has not been studied in the context of aspirin resistance. We compared RGS mRNA levels in platelets from 39 aspirin-resistant patients and 50 aspirin-sensitive patients with metabolic syndrome. Although there were no clinical differences between the two groups, transcripts of RGS2, RGS10, and RGS18 were significantly higher in aspirin-resistant patients than in aspirin-sensitive patients. This study is the first to demonstrate that RGS transcripts are elevated in aspirin-resistant platelets from patients with metabolic syndrome.
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Aqueous batteries based on mixed monovalence metal ions: a new battery family.
ChemSusChem
PUBLISHED: 02-21-2014
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As existing battery technologies struggle to meet the requirements for widespread use in the field of large-scale energy storage, new concepts are urgently needed to build batteries with high energy density, low cost, and good safety. Here, we demonstrate two new aqueous batteries based on two monovalence metal ions (Li(+) /K(+) and Na(+) /K(+) ) as charge-transfer ions, Ni1 Zn1 HCF/TiP2 O7 and Ni1 Zn1 HCF/NaTi2 (PO4 )3 . These new batteries are unlike the conventional "rocking-chair" aqueous metal-ion batteries based on the migration of one type of shuttle ion between cathode and anode. They can deliver specific energy of 46 Wh kg(-1) and 53 Wh kg(-1) based on the total mass of active materials; this is superior to current aqueous battery systems based on sodium-ion and/or potassium-ion technologies. These two new batteries together with the previously developed Li(+) /Na(+) mixed-ion battery not only constitute a new battery family for energy storage, but also greatly broaden our horizons for battery research.
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New-concept batteries based on aqueous Li+/Na+ mixed-ion electrolytes.
Sci Rep
PUBLISHED: 03-19-2013
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Rechargeable batteries made from low-cost and abundant materials operating in safe aqueous electrolytes are attractive for large-scale energy storage. Sodium-ion battery is considered as a potential alternative of current lithium-ion battery. As sodium-intercalation compounds suitable for aqueous batteries are limited, we adopt a novel concept of Li(+)/Na(+) mixed-ion electrolytes to create two batteries (LiMn2O4/Na0.22MnO2 and Na0.44MnO2/TiP2O7), which relies on two electrochemical processes. One involves Li(+) insertion/extraction reaction, and the other mainly relates to Na(+) extraction/insertion reaction. Two batteries exhibit specific energy of 17 Wh kg(-1) and 25 Wh kg(-1) based on the total weight of active electrode materials, respectively. As well, aqueous LiMn2O4/Na0.22MnO2 battery is capable of separating Li(+) and Na(+) due to its specific mechanism unlike the traditional "rocking-chair" lithium-ion batteries. Hence, the Li(+)/Na(+) mixed-ion batteries offer promising applications in energy storage and Li(+)/Na(+) separation.
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Small molecule structure correctors abolish detrimental effects of apolipoprotein E4 in cultured neurons.
J. Biol. Chem.
PUBLISHED: 12-12-2011
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Apolipoprotein E4 (apoE4), the major genetic risk factor for late onset Alzheimer disease, assumes a pathological conformation, intramolecular domain interaction. ApoE4 domain interaction mediates the detrimental effects of apoE4, including decreased mitochondrial cytochrome c oxidase subunit 1 levels, reduced mitochondrial motility, and reduced neurite outgrowth in vitro. Mutant apoE4 (apoE4-R61T) lacks domain interaction, behaves like apoE3, and does not cause detrimental effects. To identify small molecules that inhibit domain interaction (i.e. structure correctors) and reverse the apoE4 detrimental effects, we established a high throughput cell-based FRET primary assay that determines apoE4 domain interaction and secondary cell- and function-based assays. Screening a ChemBridge library with the FRET assay identified CB9032258 (a phthalazinone derivative), which inhibits domain interaction in neuronal cells. In secondary functional assays, CB9032258 restored mitochondrial cytochrome c oxidase subunit 1 levels and rescued impairments of mitochondrial motility and neurite outgrowth in apoE4-expressing neuronal cells. These benefits were apoE4-specific and dose-dependent. Modifying CB9032258 yielded well defined structure-activity relationships and more active compounds with enhanced potencies in the FRET assay (IC(50) of 23 and 116 nm, respectively). These compounds efficiently restored functional activities of apoE4-expressing cells in secondary assays. An EPR binding assay showed that the apoE4 structure correction resulted from direct interaction of a phthalazinone. With these data, a six-feature pharmacophore model was constructed for future drug design. Our results serve as a proof of concept that pharmacological intervention with apoE4 structure correctors negates apoE4 detrimental effects in neuronal cells and could be further developed as an Alzheimer disease therapeutic.
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[Boron background value survey of some foodstuffs in 12 provinces of China and boron primary intake estimation of Chinese habitants].
Wei Sheng Yan Jiu
PUBLISHED: 08-25-2011
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To learn boron background value of some foodstuffs in China and estimation the primary intake of boron.
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[Assessment of dietary iodine intake of population in non-high-iodine areas in China].
Wei Sheng Yan Jiu
PUBLISHED: 05-13-2011
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To assess the potential risk of dietary iodine insufficiency of population in non-high-iodine areas (water iodine < 150 microg/L) in China.
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A rapid and sensitive LC-MS/MS assay for the quantitation of deacetyl mycoepoxydiene in rat plasma with application to preclinical pharmacokinetics studies.
J. Chromatogr. B Analyt. Technol. Biomed. Life Sci.
PUBLISHED: 04-21-2011
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The purpose of this study was to develop and validate a high-performance liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for analysis of the deacetyl mycoepoxydiene in rat plasma. The analyte and internal standard (I.S.), benorilate, were extracted from rat plasma by precipitation protein and separated on a C(18) column using acetonitrile-0.5% formic acid as mobile phase. Detection was performed using a turbo-spray ionization source and mass spectrometric positive multi-reaction-monitoring-mode (+MRM) at an ion voltage of +4800 V. The assay was linear over the concentration range 5-5000 ng/mL with the lowest limit of quantification (LLOQ) of 5 ng/mL. The method also afforded satisfactory results in terms of the sensitivity, specificity, precision (intra- and inter-day, RSD<5.8%), accuracy, recovery as well as the stability of the analyte under various conditions. The method was successfully applied to a preclinical pharmacokinetic study in rats after a single intravenous administration of deacetyl mycoepoxydiene 10 mg/kg.
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Structure-dependent impairment of intracellular apolipoprotein E4 trafficking and its detrimental effects are rescued by small-molecule structure correctors.
J. Biol. Chem.
PUBLISHED: 03-18-2011
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Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer disease (AD) and likely contributes to neuropathology through various pathways. Here we report that the intracellular trafficking of apoE4 is impaired in Neuro-2a cells and primary neurons, as shown by measuring fluorescence recovery after photobleaching. In Neuro-2a cells, more apoE4 than apoE3 molecules remained immobilized in the endoplasmic reticulum (ER) and the Golgi apparatus, and the lateral motility of apoE4 was significantly lower in the Golgi apparatus (but not in the ER) than that of apoE3. Likewise, the immobile fraction was larger, and the lateral motility was lower for apoE4 than apoE3 in mouse primary hippocampal neurons. ApoE4 with the R61T mutation, which abolishes apoE4 domain interaction, was less immobilized, and its lateral motility was comparable with that of apoE3. The trafficking impairment of apoE4 was also rescued by disrupting domain interaction with the small-molecule structure correctors GIND25 and PH002. PH002 also rescued apoE4-induced impairments of neurite outgrowth in Neuro-2a cells and dendritic spine development in primary neurons. ApoE4 did not affect trafficking of amyloid precursor protein, another AD-related protein, through the secretory pathway. Thus, domain interaction renders more newly synthesized apoE4 molecules immobile and slows their trafficking along the secretory pathway. Correcting the pathological structure of apoE4 by disrupting domain interaction is a potential therapeutic approach to treat or prevent AD related to apoE4.
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In vitro antitumor activity of silybin nanosuspension in PC-3 cells.
Cancer Lett.
PUBLISHED: 02-21-2011
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The present study aims to evaluate the antitumor activity of silybin nanosuspension on human prostatic carcinoma PC-3 cell line in vitro. Silybin nanosuspension was prepared by the high pressure homogenization (HPH) method. MTT assay, observation of morphological changes and apoptotic body showed that silybin nanosuspension could significantly enhance the in vitro cytotoxicity against PC-3 cells compared to the silybin solution. Flow cytometric (FCM) analysis demonstrated that silybin nanosuspension induced G1 cycle arrest and apoptosis in PC-3 cells. Thereby, the overall results suggest that the silybin nanosuspension represents a potential source of medicine for the treatment of human prostate cancer.
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A rat model of Shuang Huang Lian injection-induced anaphylaxis.
Asian Pac. J. Allergy Immunol.
PUBLISHED: 11-03-2010
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ShuangHuangLian Injection (SHLI) has induced many serious anaphylactic diseases, becoming a threat to the public health. However, study of the mechanism of the reaction and therapeutic approaches to it have been hindered by the lack of suitable animal models.
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Electron transport in high-resistance semiconductor nanowires through two-probe measurements.
Phys Chem Chem Phys
PUBLISHED: 07-26-2010
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Since the successful fabrication of semiconductor nanowires, various techniques have been developed to contact these nanowires and to probe their intrinsic electrical properties. Although many novel quasi one-dimensional materials such as Pb(1 - x)Mn(x)Se nanoarrays were recently produced, their intrinsic electron transport properties have not been extensively studied so far. In this work, we demonstrate that an ordinary source-drain configuration of field-effect transistors or the two-probe measurement can be applied to the exploration of the intrinsic properties of nanowires. This two-probe measurement approach also works on highly resistive nanowires without an Ohmic contact issue. By using this method, electron transport behavior, resistivity, and carrier concentrations of ZnO, InP, GaP, and Pb(1 - x)Mn(x)Se semiconductor nanowires have been investigated. Due to the tiny cross-section and few conducting channels, a nanomaterial usually reveals an ultra high resistance. This technique demonstrates a two-probe characterization of nanostructures, paving the simplest way toward electrical characterizations of all high-resistance nanomaterials such as deoxyribonucleic acid (DNA), molecules and organics.
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Development and in vitro evaluation of deacety mycoepoxydiene nanosuspension.
Colloids Surf B Biointerfaces
PUBLISHED: 07-01-2010
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Deacety mycoepoxydiene (DM), extracted from Phomopsis sp. A123 of thalassiomycetes, is a novel and potent anti-cancer agent. Due to its physicochemical characteristics, the drug, a poorly water-soluble weak acid, shows poor solubility and dissolution characteristics. To improve the solubility and dissolution, formulation of DM as nanosuspension has been performed in this study. Nanosuspensions were developed by high-pressure homogenization (HPH) (DissoCubes(®) Technology) and transformed into dry powder by freeze-drying. The nanosuspension produced was then investigated using optical microscope, photon correlation spectroscopy (PCS), zeta potential measurement, SEM, TEM, AFM, DSC and XRD. To verify the theoretical hypothesis on the benefit of increased surface area, in vitro saturation solubility and dissolution profile were investigated. In addition, the in vitro cell cytotoxicity was examined. Results showed that a narrow size distributed nanosuspension composed of unchanged crystalline state with a mean particle size of 515±18 nm, a polydispersity index of 0.12±0.03 and a zeta potential of -23.1±3.5 mV was obtained. In the in vitro dissolution test an accelerated dissolution velocity and increased saturation solubility could be shown for the MD nanosuspension. The in vitro cytotoxicity experiments provided evidence for an enhanced efficacy of the DM nanosuspension formulation compared to free DM solution. Taken together, these results illustrate the opportunity to formulate DM in nanosuspension form as an anti-prostate cancer delivery system.
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[Comparison of immunosuppression induced by different doses of cyclophosphamide in normal mice].
Wei Sheng Yan Jiu
PUBLISHED: 06-24-2010
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To compare the methods for developing immune-suppressed mice models induced by cyclophosphamide (CTX) with different dosages and ways.
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Synthetic methodologies for carbon nanomaterials.
Adv. Mater. Weinheim
PUBLISHED: 06-08-2010
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Carbon nanomaterials have advanced rapidly over the last two decades and are among the most promising materials that have already changed and will keep on changing human life. Development of synthetic methodologies for these materials, therefore, has been one of the most important subjects of carbon nanoscience and nanotechnology, and forms the basis for investigating the physicochemical properties and applications of carbon nanomaterials. In this Research News article, several synthetic strategies, including solvothermal reduction, solvothermal pyrolysis, hydrothermal carbonization, and soft-chemical exfoliation are specifically discussed and highlighted, which have been developed for the synthesis of novel carbon nanomaterials over the last decade.
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In vitro and in vivo evaluation of silybin nanosuspensions for oral and intravenous delivery.
Nanotechnology
PUBLISHED: 03-23-2010
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In this study, we evaluate the effect of particle sizes on the physicochemical properties of silybin and identify the influence of silybin nanosuspensions on its permeation across the Caco-2 cell monolayer. In vivo pharmacokinetic evaluation of silybin nanosuspensions was also carried out in beagle dogs. TEM, AFM and SEM analyses revealed the effect of homogenization pressure on particle size and morphology, and confirmed the existence of a surfactant-stabilizer film on the surface of nanoparticles. DSC and XRPD experiments manifested that the crystalline state was maintained as particle size was reduced and the enhanced dissolution property was due to the increased surface area. Nanosuspensions had a significant influence on drug transport across the Caco-2 cell monolayer and the enhanced dissolution velocity was responsible for the increased permeability. A pharmacokinetics study in beagle dogs further confirmed the in vitro results and demonstrated that oral administration of silybin nanosuspensions significantly increase its bioavailability compared to the coarse powder. Nanosuspensions of silybin with smaller particle size reveal a higher potential to increase their oral bioavailability; while for intravenous infusion the lower pressure produced silybin nanosuspensions appeared to maintain a more sustained drug release profile.
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A scalable, solution-phase processing route to graphene oxide and graphene ultralarge sheets.
Chem. Commun. (Camb.)
PUBLISHED: 02-02-2010
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High yield production of graphene oxide and graphene sheets with an ultralarge size (up to approximately 200 microm) was realized using a modified solution-phase method.
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Evaluation of the immunosensitizing potential of chlorogenic acid using a popliteal lymph node assay in BALB/c mice.
Food Chem. Toxicol.
PUBLISHED: 01-05-2010
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It has yet to be established whether chlorogenic acid (CGA), a common xenobiotic with potential exposure risk to humans, is associated with immune-mediated hypersensitivity reactions (HRs). The primary limitation in evaluating this potential relationship is the lack of an effective animal model for use in predicting the immunosensitizing potential of low molecular weight compounds (LMWCs). Currently, the popliteal lymph node assay (PLNA) is considered a very promising tool for assessing immunosensitizing potential of LMWCs. To determine whether CGA may possess an intrinsic capacity to stimulate or dysregulate immune responses, and if so, what mechanisms may be involved, we characterized the popliteal lymph node reaction induced by CGA in naive female BALB/c mice using both a direct PLNA (d-PLNA) and a reporter antigen PLNA (RA-PLNA) method. Our results show that CGA failed to induce immunoreactivity following a single subcutaneous injection either alone or when combined with TNP-OVA or TNP-Ficoll. These results indicated that CGA lacks the intrinsic capacity to sensitize or stimulate immune responses in BALB/c mice. Moreover, these results suggest that exposure to CGA may not represent a safety concern for humans and that removal of CGA from Traditional Chinese Medicine Injections may not significantly decrease the prevalence of HRs.
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[Safety evaluation of traditional Chinese medicine injections and study of related key technology].
Zhongguo Zhong Yao Za Zhi
PUBLISHED: 07-31-2009
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Traditional Chinese medicine (TCM) injections originated in China and have been extensively used in clinic. However, some events the adverse drug reactions (ADRs) have been reported, among which, hypersensitivity reactions (HSRs) are the main ADRs of TCM injections. To solve the ADRs of TCM injections will be the key to proceed of the modernization of TCM. This paper reviewed the current situation and causes of the ADRs of TCM injections. On the basis of primary findings obtained from the project granted by the Ministry of Science and Technology, two pivotal technologies of the safety evaluation of TCM injections were introduced, which are anaphylactoid reaction ussessment and metabonomics for TCM injections. It is expected to provide some new ideas for the breakthrough of the safety evaluation of TCM injections.
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Solution-based evolution and enhanced methanol oxidation activity of monodisperse platinum-copper nanocubes.
Angew. Chem. Int. Ed. Engl.
PUBLISHED: 05-01-2009
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Shape-controlled catalysis: High-quality Pt-Cu nanocubes with an average size of about 8 nm (see picture, scale bar = 20 nm) were synthesized from a high-temperature organic solution system in the presence of various capping ligands. These cubic Pt-Cu nanocrystals terminated with {100} facets demonstrated a superior catalytic activity towards methanol oxidation compared to similar sized Pt-Cu and Pt nanospheres.
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Soluble InP and GaP nanowires: self-seeded, solution-liquid-solid synthesis and electrical properties.
Chemistry
PUBLISHED: 04-04-2009
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A facile, self-seeded, solution-liquid-solid growth of soluble InP and GaP nanowires with a very low amount of native point defects with respect to the carrier concentrations have been synthesized (see scheme) and characterized. They are potentially promising building blocks in optoelectronic applications.We demonstrate a facile method for self-seeded, solution-liquid-solid growth of soluble InP and GaP nanowires at a temperature of approximately 300 degrees C. Both types of nanowires are single crystals with very small diameters. The synthesized InP nanowires are almost defect-free, whereas the GaP nanowires have some microtwins. The effect of reaction temperatures and input ligand/III/V (III and V indicate elements of Group 13 and 15 respectively) ratios on wire formation is discussed, and two competitive chemical pathways involved in the nanowire formation are proposed. In addition, electrical properties of these III-V nanowires, generated from the solution-based approach, were investigated for the first time. The current-voltage (I-V) and room temperature resistance investigations indicate that both InP and GaP nanowires possess very low native point defects for carrier concentrations and they could be potentially promising building blocks in optoelectronic applications.
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[Study on toxicity of hyperoside in rat embryo-fetal development].
Zhongguo Zhong Yao Za Zhi
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To observe the toxicity of hyperoside in rat embryo-fetal development, in order to provide preference for safe use of drugs during gestation period.
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Scalable synthesis of TiO2/graphene nanostructured composite with high-rate performance for lithium ion batteries.
ACS Nano
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A simple and scalable method is developed to synthesize TiO(2)/graphene nanostructured composites as high-performance anode materials for Li-ion batteries using hydroxyl titanium oxalate (HTO) as the intermediate for TiO(2). With assistance of a surfactant, amorphous HTO can condense as a flower-like nanostructure on graphene oxide (GO) sheets. By calcination, the HTO/GO nanocomposite can be converted to TiO(2)/graphene nanocomposite with well preserved flower-like nanostructure. In the composite, TiO(2) nanoparticles with an ultrasmall size of several nanometers construct the porous flower-like nanostructure which strongly attached onto conductive graphene nanosheets. The TiO(2)/graphene nanocomposite is able to deliver a capacity of 230 mA h g(-1) at 0.1 C (corresponding to a current density of 17 mA g(-1)), and demonstrates superior high-rate charge-discharge capability and cycling stability at charge/discharge rates up to 50 C in a half cell configuration. Full cell measurement using the TiO(2)/graphene as the anode material and spinel LiMnO(2) as the cathode material exhibit good high-rate performance and cycling stability, indicating that the TiO(2)/graphene nanocomposite has a practical application potential in advanced Li-ion batteries.
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Complement activation associated with polysorbate 80 in beagle dogs.
Int. Immunopharmacol.
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Polysorbate 80 (Tween® 80) is the most extensively used surfactant in parenteral drug formulation. Its application as an adjunct for intravenous drug administration is approved by the Food and Drug Administration. However, severe hypersensitive reactions, which are typical non-immune anaphylactic reactions (pseudoallergy) characterized by the release of histamine and unvaried IgE antibodies, have been associated with Tween® 80. In order to explore the non-immune anaphylactic mechanisms of Tween® 80, we performed in vivo experiments to assess the changes in physiological and hematologic indicators after intravenous injection of Tween® 80 into dogs. Tween® 80 induced the release of histamine, and a 2-fold increase in SC5b-9, 2.5-fold increase in C4d, 1.3-fold increase in Bb, while IgE remained unchanged. It also produced changes in pulmonary pressure, systemic pressure and ECG. In in vitro experiments, Tween® 80 was incubated with dog serum in the presence of an inhibitor of complement activation (EGTA/Mg(2+)). Under these conditions, Tween® 80 increased the contents of C4d and Bb. The results of this study reveal that Tween® 80 can cause cardiopulmonary distress in dogs and activate the complement system through classical and alternative pathways as indicated in both in vivo and in vitro preparations. Moreover, they demonstrate the utility of the beagle dog as an animal model for the study of complement activation-related pseudoallergy. These findings raise concerns with regard to the indiscriminate use of Tween® 80 in clinical applications.
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Formulation and pharmacokinetics evaluation of puerarin nanocrystals for intravenous delivery.
J Nanosci Nanotechnol
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Puerarin is a very widely used drug for treating coronary heart disease. Owing to its poor water solubility and the adverse drug reactions caused by cosolvents having been confirmed by SFDA, the aim of present study was to construction and evaluation the puerarin nanocrystals in vitro and in vivo. The nanocrystals prepared were characterized using PCS, AFM, TEM, SEM and DSC. For the assessment of the pharmacokinetic parameters the developed formulations have been intravenous administered to beagle dogs. Results revealed that a narrow size distributed nanocrystals composed of crystallized spherical particles with a mean particle size of 423.6 +/- 17.3 nm, a poly-dispersity index of 0.13 +/- 0.07 and a negative charges around -30 mV was obtained. Puerarin dissolution velocity and saturation solubility were enhanced by the nanocrystals. DSC analysis revealed that the crystallinity of the puerarin was preserved during the high pressure homogenization and freeze-drying processes. Administration of the nanocrystals led to a mean plasma profile with almost similarly low variations in comparison to the reference solution, however with no initial blood peak as observed with the solution formulation. The puerarin nanocrystals exhibited a significantly (P < 0.05) reduced Cmax and clearance, and a significantly (P < 0.05) greater MRT, clearance and elimination half-life compared to the puerarin solution. These results revealed the opportunity to formulate puerarin in nanocrystals for intravenous delivery with higher safety.
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Dielectrophoretic placement of quasi-zero-, one-, and two-dimensional nanomaterials into nanogap for electrical characterizations.
Electrophoresis
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DEP is one of promising techniques for positioning nanomaterials into the desirable location for nanoelectronic applications. In contrast, the lithography technique is commonly used to make ultra-thin conducting wires and narrow gaps but, due to the limit of patterning resolution, it is not feasible to make electrical contacts on ultra-small nanomaterials for a bottom-up device fabrication. Thus, integrating the lithography and dielectrophoresis, a real bottom-up fabrication can be achieved. In this work, the device with the nanogap in between two nanofinger-electrodes is made using electron-beam lithography from top down and the ultra-small nanomaterials, such as colloidal PbSe quantum dots, polyaniline nanofibers, and reduced-graphene-oxide flakes, are placed in the nanogap by DEP from bottom up. The threshold electric field for the DEP placement of PbSe nanocrystals was roughly estimated to be about 8.3 × 10(4) V/cm under our experimental configuration. After the DEP process, several procedures for reducing contact resistances are attempted and measurements of intrinsic electron transport in versatile nanomaterials are performed. It is experimentally confirmed that electron transport in both PbSe nanocrystal arrays and polyaniline nanofibers agrees well with Prof. Ping Shengs model of granular metallic conduction. In addition, electron transport in reduced-graphene-oxide flakes follows Motts 2D variable-range-hopping model. This study illustrates an integration of the electron-beam lithography and the DEP techniques for a precise manipulation of nanomaterials into electronic circuits for characterization of intrinsic properties.
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In vivo evaluation of silybin nanosuspensions targeting liver.
J Biomed Nanotechnol
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The present study investigated the production, in vivo biodistribution and hepatoprotective of two formulated silybin nanosuspensions with different particle size. The physicochemical properties of the two formulated silybin nanosuspensions were investigated by TEM, AFM and SEM. A kinetic study was conducted to evaluate the influence of particle size on the in vivo tissue distribution following intravenous administration in the mice. The in vivo hepatoprotective studies were conducted on beagle dogs with optimized setting. A clear physicochemical difference was observed among the silybin solution, larger particles and the small particles. The formulation of larger particle size was preferentially targeted at liver and spleen. The silybin nanosuspensions, administrated either intravenously or orally, presented significant (P < or = 0.05) hepatoprotective effect by reducing the serum marker enzymes such as AST, ALT, ALP, TBIL and GGT. Histopathological study further confirmed the hepatoprotective activity of the two silybin nanosuspensions formulations when compared with the CCl4 treated control group. These results indicate that the nanosuspensions approaches could be used to improve the drug target delivery and therapeutic efficacy of the silybin.
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Induction of dendritic spines by ?2-containing nicotinic receptors.
J. Neurosci.
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Glutamatergic synapses are located mostly on dendritic spines in the adult nervous system. The spines serve as postsynaptic compartments, containing components that mediate and control the synaptic signal. Early in development, when glutamatergic synapses are initially forming, waves of excitatory activity pass through many parts of the nervous system and are driven in part by a class of heteropentameric ?2-containing nicotinic acetylcholine receptors (?2*-nAChRs). These ?2*-nAChRs are widely distributed and, when activated, can depolarize the membrane and elevate intracellular calcium levels in neurons. We show here that ?2*-nAChRs are essential for acquisition of normal numbers of dendritic spines during development. Mice constitutively lacking the ?2-nAChR gene have fewer dendritic spines than do age-matched wild-type mice at all times examined. Activation of ?2*-nAChRs by nicotine either in vivo or in organotypic slice culture quickly elevates the number of spines. RNA interference studies both in vivo and in organotypic culture demonstrate that the ?2*-nAChRs act in a cell-autonomous manner to increase the number of spines. The increase depends on intracellular calcium and activation of calcium, calmodulin-dependent protein kinase II. Absence of ?2*-nAChRs in vivo causes a disproportionate number of glutamatergic synapses to be localized on dendritic shafts, rather than on spines as occurs in wild type. This shift in synapse location is found both in the hippocampus and cortex, indicating the breadth of the effect. Because spine synapses differ from shaft synapses in their signaling capabilities, the shift observed is likely to have significant consequences for network function.
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Glutamatergic synapse formation is promoted by ?7-containing nicotinic acetylcholine receptors.
J. Neurosci.
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Glutamate is the primary excitatory transmitter in adult brain, acting through synapses on dendritic spines and shafts. Early in development, however, when glutamatergic synapses are only beginning to form, nicotinic cholinergic excitation is already widespread; it is mediated by acetylcholine activating nicotinic acetylcholine receptors (nAChRs) that generate waves of activity across brain regions. A major class of nAChRs contributing at this time is a species containing ?7 subunits (?7-nAChRs). These receptors are highly permeable to calcium, influence a variety of calcium-dependent events, and are diversely distributed throughout the developing CNS. Here we show that ?7-nAChRs unexpectedly promote formation of glutamatergic synapses during development. The dependence on ?7-nAChRs becomes clear when comparing wild-type (WT) mice with mice constitutively lacking the ?7-nAChR gene. Ultrastructural analysis, immunostaining, and patch-clamp recording all reveal synaptic deficits when ?7-nAChR input is absent. Similarly, nicotinic activation of ?7-nAChRs in WT organotypic culture, as well as cell culture, increases the number of glutamatergic synapses. RNA interference demonstrates that the ?7-nAChRs must be expressed in the neuron being innervated for normal innervation to occur. Moreover, the deficits persist throughout the developmental period of major de novo synapse formation and are still fully apparent in the adult. GABAergic synapses, in contrast, are undiminished in number under such conditions. As a result, mice lacking ?7-nAChRs have an altered balance in the excitatory/inhibitory input they receive. This ratio represents a fundamental feature of neural networks and shows for the first time that endogenous nicotinic cholinergic signaling plays a key role in network construction.
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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.

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

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.