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ABSTRACT: Thermo- and pH-sensitive ionic-crosslinked hollow spheres from self-assembly of chitosan-graft-poly(N-isopropylacrylamide) (CS-g-PNIPAM) for controlled release of 5-fluorouracil were studied. CS-g-PNIPAM aggregated into core-shell micelles with collapsed PNIPAM as the core and CS as the shell at the temperature above LCST. Ionic crosslinking reagent sodium tripolyphosphate (TPP) was used to crosslink the shell to form hollow spheres after cooling to room temperature. The size of hollow spheres was manipulated by changing pH or temperature of the environment. The CS-g-PNIPAM hollow spheres with plenty of inner cavities showed high loading capacity for 5-fluorouracil due to the polymer-drug interactions. Release of 5-fluorouracil from nanoparticles was accelerated at the temperature above LCST ascribed to the destruction of polymer-drug interactions and the decrease of particles size. Changing pH or ionic strength deformed the structure hollow spheres, which led to the increase of drug release. These hollow nanoparticles with environmentally sensitive properties are expected to be utilized in the field of intelligent drug delivery.
International journal of biological macromolecules 01/2013; · 2.37 Impact Factor
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ABSTRACT: In this paper, self-assembled thermo-sensitive polyelectrolyte complex nanoparticles formed from chitosan-graft-poly(N-isopropylacrylamide)/carboxymethyl cellulose (CS-g-PNIPAM/CMC) were prepared for entrapment and release of 5-fluorouracil (5-FU). The morphology and size of the nanoparticles were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The polyelectrolyte complex nanoparticles showed a narrow distribution with an average diameter of about 200nm. The hydrogen bonding interaction between nanoparticles and 5-FU was determined by Fourier-transformed infrared spectroscopy (FTIR). Increasing temperature or pH of the solutions, a sustained and controlled drug release was observed. The chemical cross-linking was an efficient way to decrease the drug release rate at the initial stage. The novel complex nanoparticles with environmentally sensitive properties are expected to be used in the field of intelligent drug delivery system.
International journal of biological macromolecules 09/2012; 51(5):1109-15. · 2.37 Impact Factor
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ABSTRACT: Size-resolved airborne particles (9-stages) in urban Xi'an, China, during summer and winter were measured for molecular distributions and stable carbon isotopic compositions of dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls. To our best knowledge, we report for the first time the size-resolved differences in stable carbon isotopic compositions of diacids and related compounds in continental organic aerosols. High ambient concentrations of terephthalic (tPh, 379 ± 200 ng m(-3)) and glyoxylic acids (ωC(2), 235 ± 134 ng m(-3)) in Xi'an aerosols during winter compared to those in other Chinese cities suggest significant emissions from plastic waste burning and coal combustions. Most of the target compounds are enriched in the fine mode (<2.1 μm) in both seasons peaking at 0.7-2.1 μm. However, summertime concentrations of malonic (C(3)), succinic (C(4)), azelaic (C(9)), phthalic (Ph), pyruvic (Pyr), 4-oxobutanoic (ωC(4)), and 9-oxononanoic (ωC(9)) acids, and glyoxal (Gly) in the coarse mode (>2.1 μm) are comparable to and even higher than those in the fine mode (<2.1 μm). Stable carbon isotopic compositions of the major organics are higher in winter than in summer, except oxalic acid (C(2)), ωC(4), and Ph. δ(13)C of C(2) showed a clear difference in sizes during summer, with higher values in fine mode (ranging from -22.8‰ to -21.9‰) and lower values in coarse mode (-27.1‰ to -23.6‰). The lower δ(13)C of C(2) in coarse particles indicate that coarse mode of the compound originates from evaporation from fine mode and subsequent condensation/adsorption onto pre-existing coarse particles. Positive linear correlations of C(2), sulfate and ωC(2) and their δ(13)C values suggest that ωC(2) is a key intermediate, which is formed in aqueous-phase via photooxidation of precursors (e.g., Gly and Pyr), followed by a further oxidation to produce C(2).
Environmental Science & Technology 04/2012; 46(9):4783-91. · 4.80 Impact Factor
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ABSTRACT: We have previously reported that the absence of leptin signaling in β-cells enhances glucose-stimulated insulin secretion and improves glucose tolerance in vivo. To investigate the relevance of β-cell leptin signaling in the context of postprandial or therapeutic insulin secretion, we examined the cross talk between leptin and glucagon-like peptide (GLP)-1 and sulfonylurea actions. Single and size-matched islets isolated from control or pancreas-specific leptin receptor knockout (pancreas-ObR-KO) mice were treated either with GLP-1 or with glibenclamide. Leptin suppressed GLP-1-stimulated intracellular Ca(2+) concentrations ([Ca(2+)](i)) increase that paralleled the decrease in insulin secretion in controls. In contrast, and as expected, the ObR-KO islets were nonresponsive to leptin, and instead, showed a 2.8-fold greater GLP-1-stimulated [Ca(2+)](i) increase and a 1.7-fold greater insulin secretion. Phosphorylation of cAMP-responsive element binding protein was enhanced, and phosphodiesterase enzymatic activity was suppressed in MIN6 β-cells with ObR knockdown compared with controls. The ObR-KO islets also showed significantly higher glibenclamide-induced insulin secretion compared with control islets, whereas [Ca(2+)](i) was similar to the controls. These data support enhanced insulinotropic effects of glucose, GLP-1, and sulfonylureas in the islets lacking leptin signaling with potential therapeutic implications.
Molecular Endocrinology 04/2012; 26(6):967-76. · 4.54 Impact Factor
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ABSTRACT: Empirical monitoring studies of catchment-scale Escherichia coli burden to land from agriculture are scarce. This is not surprising given the complexity associated with the temporal and spatial heterogeneity in the excretion of livestock faecal deposits and variability in microbial content of faeces. However, such information is needed to appreciate better how land management and landscape features impact on water quality draining agricultural landscapes. The aim of this study was to develop and test a field-based protocol for determining the burden of E. coli in a small headwater catchment in the UK. Predictions of E. coli burden using an empirical model based on previous best estimates of excretion and shedding rates were also evaluated against observed data. The results indicated that an empirical model utilising key parameters was able to satisfactorily predict E. coli burden on pasture most of the time, with 89% of observed values falling within the minimum and maximum range of predicted values. In particular, the overall temporal pattern of E. coli burden on pasture is captured by the model. The observed and predicted values recorded a disagreement of >1 order of magnitude on only one of the nine sampling dates throughout an annual period. While a first approximation of E. coli burden to land, this field-based protocol represents one of the first comprehensive approaches for providing a real estimate of a dynamic microbial reservoir at the headwater catchment scale and highlights the utility of a simple dynamic empirical model for a more economical prediction of catchment-scale E. coli burden.
Environment international 03/2012; 43:6-12. · 4.79 Impact Factor
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ABSTRACT: The brainstem premotor neurons of the facial nucleus (VII) and hypoglossal (XII) nucleus can integrate orofacial nociceptive input from the caudal spinal trigeminal nucleus (Vc) and coordinate orofacial nociceptive reflex (ONR) responses. However, the synaptoarchitectures of the ONR pathways are still unknown. In the current study, we examined the distribution of GABAergic premotor neurons in the brainstem local ONR pathways, their connections with the Vc projections joining the brainstem ONR pathways and the neurochemical properties of these connections. Retrograde tracer fluoro-gold (FG) was injected into the VII or XII, and anterograde tracer biotinylated dextran amine (BDA) was injected into the Vc. Immunofluorescence histochemical labeling for inhibitory/excitatory neurotransmitters combined with BDA/FG tracing showed that GABAergic premotor neurons were mainly distributed bilaterally in the ponto-medullary reticular formation with an ipsilateral dominance. Some GABAergic premotor neurons made close appositions to the BDA-labeled fibers coming from the Vc, and these appostions were mainly distributed in the parvicellular reticular formation (PCRt), dorsal medullary reticular formation (MdD), and supratrigeminal nucleus (Vsup). We further examined the synaptic relationships between the Vc projecting fibers and premotor neurons in the VII or XII under the confocal laser-scanning microscope and electron microscope, and found that the BDA-labeled axonal terminals that made asymmetric synapses on premotor neurons showed vesicular glutamate transporter 2 (VGluT2) like immunoreactivity. These results indicate that the GABAergic premotor neurons receive excitatory neurotransmission from the Vc and may contribute to modulating the generation of the tonic ONR.
PLoS ONE 01/2012; 7(3):e34435. · 4.09 Impact Factor
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ABSTRACT: Esophageal squamous cell carcinoma (ESCC) is a predominant type of esophageal cancer, which is a malignant tumor originating from the esophageal mucosa or gland and is aggressive with poor prognosis. Identification of new gene expression patterns would be helpful for providing new targets for the early detection and treatment of ESCC patients. In the present study, we employed cDNA array technology to compare gene expression profiles between ESCC tissues and adjacent normal epithelial tissues from ESCC patients. There was at least a 4-fold change in the expression levels of 72 genes that were significantly increased and 107 genes that were decreased in ESCC compared with normal esophageal epithelium. Among them, genes known to be involved in ESCC were found, including matrix metalloproteinases, transcription factors SOX-4 and SOX-17, the Wingless-type MMTV integration site family member 2, and cell cycle regulators. Moreover, we have newly identified the two genes that are down-regulated in ESCC: monoamine oxidase A, an enzyme that catalyzes monoamines oxidation and 15-hydroxyprostaglandin dehydrogenase [NAD+], a prostaglandin-synthesizing enzyme that physiologically antagonizes COX-2. Likewise, we found the three genes that are up-regulated in ESCC: CD7, a cell surface glycoprotein member of the immunoglobulin superfamily, LIM-domain kinase 1, a small subfamily with an unique combination of two N-terminal LIM motifs and a C-terminal protein kinase domain, and TTK protein kinase, a previously unidentified member of the kinase family. These newly identified genes may be involved in the progression of the tumor and/or represent properties specific to ESCC.
The Tohoku Journal of Experimental Medicine 01/2012; 226(4):301-11. · 1.24 Impact Factor
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ABSTRACT: Doxorubicin, an approved drug for cancer therapy, was recently found to be a potent agent to augment adeno-associated virus (AAV)-mediated transgene expression, especially in airway cells. Recombinant AAV type 2 (rAAV-2) has been shown to preferentially transduce neural tissues and is considered as the primary viral vector for the treatments of various neurodegenerative diseases including Parkinson's disease (PD). The goal of this study is to investigate whether doxorubicin can be applied to increase the efficacy of rAAV-2 transduction in the central nervous system. We co-administrated doxorubicin with AV2.luc/EGFP into the rat striatum, a preferred target site for PD gene therapy, and found that doxorubicin augmented rAAV-2 transduction dramatically without significant cytotoxicity and alteration of rAAV-2 tropism. By evaluating the effects of doxorubicin on rAAV-2 transduction in PC12 and MN9D neuronal cells, we found that doxorubicin appeared to promote the nuclear accumulation of rAAV-2, but did not affect viral binding or uptake. Our data suggested that doxorubicin might play an important role in modulating rAAV-2 intracellular trafficking in neuron-like cells. Our study also provided the initial in vivo evidence to facilitate AAV-mediated gene expression in the midbrain with the treatment of doxorubicin.
Neurochemistry International 06/2009; · 2.86 Impact Factor
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ABSTRACT: Ge2Sb2Te5 films were deposited by RF magnetron sputtering on Si(100)/SiO2 substrates. N+ ion was implanted into Ge2Sb2Te5 films. Two obvious steps were observed in the resistance–temperature curve of the Ge2Sb2Te5-N film with a minor nitrogen implant dose. The two steps may change into one step because the phase transition from FCC to hexagonal structure was suppressed by nitrogen implantation if the nitrogen implant dose is higher than 4.51 × 1016 cm−2. The favourite nitrogen implant dose is about 6.44 × 1015 to 1.92 × 1016 cm−2 in our study. This phenomenon is very important for multilevel storage. Three-level storage with Ge2Sb2Te5-N media for chalcogenide random access memory (C-RAM) can be performed easily, and hence, the capacity of C-RAM will be dramatically increased.
Semiconductor Science and Technology 04/2004; 19(6):L61. · 1.72 Impact Factor
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Jingqiang Wang,
Jie Wen,
Jingxiang Li,
Jianning Yin,
Qingyu Zhu,
Hao Wang,
Yongkui Yang,
E'de Qin,
Bo You,
Wei Li, [......],
Changqing Zeng,
Jianqiu Fang,
Jun Yu,
Jian Wang,
Huanming Yang,
Matthew B West,
Aruni Bhatnagar,
Youyong Lu,
Ningzhi Xu,
Siqi Liu
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ABSTRACT: The widespread threat of severe acute respiratory syndrome (SARS) to human life has spawned challenges to develop fast and accurate analytical methods for its early diagnosis and to create a safe antiviral vaccine for preventive use. Consequently, we thoroughly investigated the immunoreactivities with patient sera of a series of synthesized peptides from SARS-coronavirus structural proteins.
We synthesized 41 peptides ranging in size from 16 to 25 amino acid residues of relatively high hydrophilicity. The immunoreactivities of the peptides with SARS patient sera were determined by ELISA.
Four epitopic sites, S599, M137, N66, and N371-404, located in the SARS-coronavirus S, M, and N proteins, respectively, were detected by screening synthesized peptides. Notably, N371 and N385, located at the COOH terminus of the N protein, inhibited binding of antibodies to SARS-coronavirus lysate and bound to antibodies in >94% of samples from SARS study patients. N385 had the highest affinity for forming peptide-antibody complexes with SARS serum.
Five peptides from SARS structural proteins, especially two from the COOH terminus of the N protein, appear to be highly immunogenic and may be useful for serologic assays. The identification of these antigenic peptides contributes to the understanding of the immunogenicity and persistence of SARS coronavirus.
Clinical Chemistry 12/2003; 49(12):1989-96. · 7.91 Impact Factor
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ABSTRACT: In this paper, the effect of nitrogen implantation on the structure and sheet resistance of Ge2Sb2Te5 film was studied in details. It is indicated that the phase transition of Ge2Sb2Te5 film from face-centered-cubic (FCC) to hexagonal (HEX) structure was suppressed by nitrogen implantation. From the results of X-ray diffraction, Raman spectra, and X-ray photoelectron spectroscopy measurements, more Te atom bonds to Sb–Sb bond and N atom bonds to Ge atom forming Ge3N4 in the nitrogen-doped Ge2Sb2Te5 film with the increase of implant dose. The sheet resistance of Ge2Sb2Te5–N film decreases with the increase of implant dose at low annealing temperature because the unit cell of crystalline Ge2Sb2Te5 film with FCC structure was distorted due to nitrogen atom occupying the tetrahedral interstitial site and the defects in film increased, which results in larger number of current carrier. On the contrary, the sheet resistance of Ge2Sb2Te5–N film increases slightly with the increase of implant dose at high annealing temperature. The two major reasons may be that the grain refinement, which results in being scattered of current carrier by grain boundary, and the suppression of phase transition from FCC to HEX structure.
Thin Solid Films.
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ABSTRACT: The objectives of this study were to: (1) characterize the evolutional tendency of the non-hydraulic root-sourced signal (NRS) from wheat wild relatives to its modern hexaploid species, and (2) test whether species sensitivity to the NRS was allied with their drought tolerance profiles. The NRS was judged to begin when there was a significant lowering of stomatal conductance without change in leaf relative water content (RWC). The lethal soil water content (LSWC) was operationally characterized as the soil water content (SWC) at the drying lethal point of wheat plants. The threshold of soil water content (TSWC) at which the NRS was triggered, and the LSWC differed amongst six wheat species. For “MO1” and “MO4” representing ‘diploid’ species, the TSWC and the LSWC were initiated successively at about 51% FWC (field water capacity) and about 30% FWC, respectively. Conversely, “Plateau 602” and “Longchun 8139-2” (modern hexaploid species) exhibited the TSWC and the LSWC between about 68% FWC and less than 14% FWC, a much wider threshold range (TR). Increasing TSWC was significantly correlated with decreasing LSWC (r = 0.9464**). The widened TR from the TSWC to the LSWC was also significantly correlated with longer survival days (SD) and higher maintenance ratio of grain yield (MRGY), respectively (r = 0.9411** and 0.8068*, respectively). Meanwhile, those species having higher TSWC had the least reduction ratio of stomatal conductance under the decreasing soil moisture from −0.2 to −1 MPa. This suggests that advances in yield performance and drought tolerance would be made evolutionally by targeted selection for an earlier onset of NRS.
Environmental and Experimental Botany.
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ABSTRACT: The objective of this study was to characterize the elemental carbon and organic carbon (EC and OC, respectively) content of aerosol particles (PM2.5) collected at Tongliao, a site in the Horqin Sandland of northeastern China. During spring 2005, the PM2.5 mass concentration was 126±71 μg·m−3, with higher dust concentrations during five dust storms than on non-dusty days (255±77 vs. 106±44 μg·m−3). The average OC and EC concentrations in PM2.5 determined by a thermal/optical reflectance method were 15.7±7.3 μg·m−3 and 3.3±1.7 μg·m−3, respectively, and carbonaceous aerosol accounted for 9.9% of the PM2.5 mass during dust storms compared to 21.7% on normal days. The average ratios of OC to EC during dust storms were similar to those on non-dusty days, and the correlation coefficient between OC and EC was high, 0.86. The high OC/EC ratios, the distributions of eight carbon fractions, and the strong relationship between K with OC and EC indicate that rural biomass burning was the dominant contributor to the regional carbonaceous aerosol.
China Particuology.
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ABSTRACT: Ge2Sb2Te5 films were deposited by rf magnetron sputtering on Si(1 0 0)/SiO2 substrates. In order to increase the Ge2Sb2Te5 sheet resistance, O+ ion was implanted into Ge2Sb2Te5 films. The effect of oxygen implantation on the structure of Ge2Sb2Te5 film was studied in details using XRD, Raman spectra, and XPS methods. It is indicated that the structure of crystalline Ge2Sb2Te5-O annealed at 250 °C is identified as a FCC structure even when oxygen implant fluence reaches 1.29 × 1017 ions per cm2 and the lattice parameter increases as oxygen implant fluence increasing. However, phase separation takes place when annealing temperature is 450 °C. In the case of the high fluence (higher than 6.44 × 1016 ions per cm2) samples, phase separation no longer takes place and phase transition from FCC to hexagonal structure is suppressed by oxygen implantation. Oxygen implantation has great effect on the resistance-annealing behaviour of Ge2Sb2Te5 film, which may be origin from the structural changes including defect formation, phase separation, suppression of phase transition from FCC to hexagonal structure, and the refinement of grain size, etc. The Rs of Ge2Sb2Te5-O film is higher than that of Ge2Sb2Te5 film when annealing temperature is higher than 340 °C, which may be caused by phase separation and current carrier scattering by crystallite boundary.
Applied Surface Science 242:62-69. · 2.10 Impact Factor
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ABSTRACT: Two series of size-selective aerosol samples, PM2.5 and PM10, were collected in Beijing from July 2002 to July 2003. The samples were analyzed for levoglucosan and related saccharidic compounds, organic and elemental carbon, and ionic species. Levoglucosan and related saccharidic compounds were mostly present in the fine size fraction. The contribution from biomass burning to the carbonaceous aerosol in Beijing was estimated; biomass burning was responsible for 18–38% of the PM2.5 organic carbon and for 14–32% of the PM10 organic carbon. The biomass burning marker levoglucosan was present all year round in Beijing. High levoglucosan concentrations in October and November were attributed to corn field burning and burning of fallen leaves, while the high level observed on 7 May 2003 was tracked back to a boreal forest fire more than 1000 km away in northeastern China. The biomass burning contribution to the Beijing aerosol is made up of two parts, a background component, which is due to biofuel burning all year round in the neighboring countryside households, and a superimposed component from seasonal crop burning events and wild fires.
Atmospheric Environment.
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ABSTRACT: For the 90° equal-width open-channel junction flow, the Reynolds averaged Navier-Stokes equations are solved while using the 3-D k − ω model. The mean flow pattern and the secondary current are obtained. The model is validated by experimental data, and then applied to investigate the effect of the discharge ratio on the shape of separation zone shape, the cross-sectional mean flow angle and the contraction coefficient. The results are fairly close to those of the prior studies. The numerical modeling is both less time-consuming and less expensive to obtain the various flow parameters needed for engineering design.
Journal of Hydrodynamics, Ser. B.
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ABSTRACT: To evaluate effect of diabetes on transient ischemia-induced brain damage and autophagy activity, streptozotocin (STZ)-induced diabetic mellitus (DM) mice were subjected to transient common carotid artery occlusion (CCAO) operation. After the operation, immunohistochemistry and transmission electron microscopy (EM) were performed to investigate the astrocytes activation, amyloid-β protein (Aβ) expression and accumulation of autophagy-like vacuoles containing electron-dense material (avd); and hallmarks of autophagy, the microtubule-associated protein light chain 3 (LC3)-II, was detected by western blot analysis. The results showed that DM amplified stroke-induced astrocytes activation and Aβ generation. Western blot analysis showed that LC3-II conjugate was drastically up-regulated at early stages post ischemia and it last for at least 72 h in DM mice brain. DM mice demonstrated increased baseline level of LC3-II as comparing to normal mice; DM also amplified stroke-induced LC3-II level. Under EM, avd was most markedly accumulated in neurons of DM mice brain after ischemia. Immunofluorescence double-staining showed that most Aβ and autophagosomes co-localized. Therefore, our results suggested that exacerbation of ischemia-induced Aβ generation by diabetes might be associated with autophagy activation in mice brain, and modulating neuronal autophagy might be a new therapeutic strategy to depress the risk of development of dementia in diabetic patients with stroke.
Neuroscience Letters.
