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Find video protocols related to scientific articles indexed in Pubmed.
Evaluation of Normal Fetal Ductus Venosus Using B-Flow Imaging with Spatiotemporal Image Correlation and Traditional Color Doppler Echocardiography.
Echocardiography
PUBLISHED: 10-18-2014
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To explore the feasibility of using four-dimensional echocardiography with B-flow and spatiotemporal image correlation (4DBF-STIC) imaging technology to detect fetal ductus venosus (DV), and establish the normal reference range for the ductus venosus diameter at 18-40 weeks gestation.
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[Sequencing and analysis of N gene of street rabies virus isolated from different hosts in Zhejiang province].
Zhonghua Liu Xing Bing Xue Za Zhi
PUBLISHED: 10-09-2014
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To elucidate the characteristics of genetic variability and its relationship with prevalence, through sequencing and analysis of N gene among street rabies virus isolated from different hosts (homo sapiens, ferret badger, dog) in Zhejiang province.
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Organized assemblies of colloids formed at the poles of micrometer-sized droplets of liquid crystal.
Soft Matter
PUBLISHED: 10-07-2014
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We report on the formation of organized assemblies of 1 ?m-in-diameter colloids (polystyrene (PS)) at the poles of water-dispersed droplets (diameters 7-20 ?m) of nematic liquid crystal (LC). For 4-cyano-4'-pentylbiphenyl droplets decorated with two to five PS colloids, we found 32 distinct arrangements of the colloids to form at the boojums of bipolar droplet configurations. Significantly, all but one of these configurations (a ring comprised of five PS colloids) could be mapped onto a local (non-close packed) hexagonal lattice. To provide insight into the origin of the hexagonal lattice, we investigated planar aqueous-LC interfaces, and found that organized assemblies of PS colloids did not form at these interfaces. Experiments involving the addition of salts revealed that a repulsive interaction of electrostatic origin prevented formation of assemblies at planar interfaces, and that regions of high splay near the poles of the LC droplets generated cohesive interactions between colloids that could overcome the repulsion. Support for this interpretation was obtained from a model that included (i) a long-range attraction between adsorbed colloids and the boojum due to the increasing rate of strain (splay) of LC near the boojum (splay attraction), (ii) an attractive inter-colloid interaction that reflects the quadrupolar symmetry of the strain in the LC around the colloids, and (iii) electrostatic repulsion between colloids. The model predicts that electrostatic repulsion between colloids can lead to a ?1000kBT energy barrier at planar interfaces of LC films, and that the repulsive interaction can be overcome by splay attraction of the colloids to the boojums of the LC droplets. Overall, the results reported in this paper advance our understanding of the directed assembly of colloids at interfaces of LC droplets.
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AChE inhibition: One dominant factor for swimming behavior changes of Daphnia magna under DDVP exposure.
Chemosphere
PUBLISHED: 08-08-2014
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As a key enzyme that hydrolyzes the neurotransmitter acetylcholine in cholinergic synapses of both vertebrates and invertebrates, acetylcholinesterase (AChE) is strongly inhibited by organophosphates. AChE inhibition may induce the decrease of swimming ability. According to previous research, swimming behavior of different aquatic organisms could be affected by different chemicals, and there is a shortage of research on direct correlation analysis between swimming behavior and biochemical indicators. Therefore, swimming behavior and whole-body AChE activity of Daphnia magna under dichlorvos (DDVP) exposure were identified in order to clarify the relationship between behavioral responses and AChE inhibition in this study. In the beginning, AChE activity was similar in all treatments with the control. During all exposures, the tendency of AChE activity inhibition was the same as the behavioral responses of D. magna. The AChE activity of individuals without movement would decrease to about zero in several minutes. The correlation analysis between swimming behavior of D. magna and AChE activity showed that the stepwise behavioral response was mainly decided by AChE activity. All of these results suggested that the toxicity characteristics of DDVP as an inhibitor of AChE on the swimming behavior of organisms were the same, and the AChE activity inhibition could induce loss of the nerve conduction ability, causing hyperactivity, loss of coordination, convulsions, paralysis and other kinds of behavioral changes, which was illustrated by the stepwise behavioral responses under different environmental stresses.
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Analysis of bacterial pathogens causing acute diarrhea on the basis of sentinel surveillance in Shanghai, China, 2006-2011.
Jpn. J. Infect. Dis.
PUBLISHED: 07-25-2014
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Acute diarrhea is the most common infectious disease worldwide and its causes vary from one region to another. We aimed to analyze the spectrum and epidemiological characteristics of pathogens from 22,386 outpatients with acute diarrhea on the basis of surveillance data from Shanghai, China, during 2006-2011. The following 8 pathogens were isolated and identified using standard methods: Salmonella, Shigella, Vibrio cholerae, V. parahaemolyticus, enteropathogenic Escherichia coli, enterotoxigenic E. coli, enteroinvasive E. coli, and enterohemorrhagic E. coli. In total, 2,234 strains of pathogens were obtained and the overall isolation rate of these 8 pathogens gradually decreased from 17.1% in 2006 to 7.4% in 2011. V. parahaemolyticus was the most frequently identified pathogen, followed by Shigella and Salmonella. The isolation rate of V. parahaemolyticus notably varied by season, whereas Salmonella and Shigella infections showed little seasonal variation. Age-related variation was also observed. V. parahaemolyticus infection occurred more often in patients aged 20-40 years. S. enterica serovar Enteritidis and S. flexneri were the most common serotypes of Salmonella and Shigella, respectively. The descending trend observed in the isolation rate of pathogens from the current surveillance suggests an urgent requirement or improvement.
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A Study on the Effect of Neurogenesis and Regulation of GSK3?/PP2A Expression in Acupuncture Treatment of Neural Functional Damage Caused by Focal Ischemia in MCAO Rats.
Evid Based Complement Alternat Med
PUBLISHED: 07-10-2014
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170 SD rats were randomly divided to five groups. Rats in model group, no-acupuncture group, and acupuncture group were subjected to MCAO surgery. Acupuncture group received 3 consecutive acupuncture treatments at a parameter that deep in 2?mm towards apex nasi and thrust/lifted at 3 times per second for 1 minute, while model group and no-acupuncture group were no-intervention control groups. Serious neural functional damage and sharp decrease of cerebral blood flow, obvious infarction volume, increased nestin mRNA expression, and immunopositive cells population (nestin(+), BrdU(+) and nestin/BrdU(+)) were found in MCAO rats which had not been observed in normal group and sham-operated group. However, the damage was attenuated by rat's "self-healing" capacity 3 days after MCAO. And the "self-healing" capacity can be strengthen by acupuncture treatment through increasing cerebral blood flow, neurogenesis, and regulation of gene transcription or GSK-3? and PP2A expression. In conclusion, the present study indicates that the underlying mechanism of acupuncture treatment on neural functional damage caused by focal ischemia injury is a multiple interaction which may involve improved cerebral blood supply, neurogenesis, and regulation of gene transcription or GSK-3? and PP2A expression in MCAO rats.
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Design of Functional Materials based on Liquid Crystalline Droplets.
Chem Mater
PUBLISHED: 06-03-2014
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This brief perspective focuses on recent advances in the design of functional soft materials that are based on confinement of low molecular weight liquid crystals (LCs) within micrometer-sized droplets. While the ordering of LCs within micrometer-sized domains has been explored extensively in polymer-dispersed LC materials, recent studies performed with LC domains with precisely defined size and interfacial chemistry have unmasked observations of confinement-induced ordering of LCs that do not follow previously reported theoretical predictions. These new findings, which are enabled in part by advances in the preparation of LCs encapsulated in polymeric shells, are opening up new opportunities for the design of soft responsive materials based on surface-induced ordering transitions. These materials are also providing new insights into the self-assembly of biomolecular and colloidal species at defects formed by LCs confined to micrometer-sized domains. The studies presented in this perspective serve additionally to highlight gaps in knowledge regarding the ordering of LCs in confined systems.
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Prevention and treatment of viral respiratory infections by traditional Chinese herbs.
Chin. Med. J.
PUBLISHED: 04-09-2014
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This review focuses on current knowledge of traditional Chinese herbs on prevention and treatment of viral respiratory infections, especially caused by Severe Acute Respiratory Syndromes (SARS) virus, respiratory syncytial virus (RSV) and influenza viruses.
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IcgA is a virulence factor of Rhodococcus equi that modulates intracellular growth.
Infect. Immun.
PUBLISHED: 02-18-2014
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Virulence of the intracellular pathogen Rhodococcus equi depends on a 21.3-kb pathogenicity island located on a conjugative plasmid. To date, the only nonregulatory pathogenicity island-encoded virulence factor identified is the cell envelope-associated VapA protein. Although the pathogenicity islands from porcine and equine R. equi isolates have undergone major rearrangements, the virR operon (virR-icgA-vapH-orf7-virS) is highly conserved in both, suggesting these genes play an important role in pathogenicity. VirR and VirS are transcriptional regulators controlling expression of pathogenicity island genes, including vapA. Here, we show that while vapH and orf7 are dispensable for intracellular growth of R. equi, deletion of icgA, formerly known as orf5, encoding a major facilitator superfamily transport protein, elicited an enhanced growth phenotype in macrophages and a significant reduction in macrophage viability, while extracellular growth in broth remained unaffected. Transcription of virS, located downstream of icgA, and vapA was not affected by the icgA deletion during growth in broth or in macrophages, showing that the enhanced growth phenotype caused by deletion of icgA was not mediated through abnormal transcription of these genes. Transcription of icgA increased 6-fold within 2 h following infection of macrophages and remained significantly higher 48 h postinfection compared to levels at the start of the infection. The major facilitator superfamily transport protein IcgA is the first factor identified in R. equi that negatively affects intracellular replication. Aside from VapA, it is only the second pathogenicity island-encoded structural protein shown to play a direct role in intracellular growth of this pathogenic actinomycete.
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Robotic stereotactic irradiation and reirradiation for spinal metastases: safety and efficacy assessment.
Chin. Med. J.
PUBLISHED: 01-21-2014
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Spine is the most common site of bone metastases in patients with cancer. Conventional external beam radiotherapy lacks precision to allow delivery of large fraction radiation but simultaneously limit the dose to spinal cord. The purpose of this study was to evaluate the safety and efficacy of CyberKnife(®) radiation therapy for spinal metastases.
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Analysis of the internal configurations of droplets of liquid crystal using flow cytometry.
Anal. Chem.
PUBLISHED: 10-22-2013
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We report the use of flow cytometry to identify the internal ordering (director configurations) of micrometer-sized droplets of thermotropic liquid crystals (LCs) dispersed in aqueous solutions of adsorbates (surfactants and phospholipids). We reveal that changes in the configurations of the LC droplets induced by the adsorbates generate distinct changes in light scattering plots (side versus forward scattering). Specifically, when compared to bipolar droplets, radial droplets generate a narrower distribution of side scattering intensities (SSC, large angle light scattering) for a given intensity of forward scattering (FSC, small angle light scattering). This difference is shown to arise from the rotational symmetry of a radial LC droplet which is absent for the bipolar configuration of the LC droplet. In addition, the scatter plots for radial droplets possess a characteristic "S-shape", with two or more SSC intensities observed for each intensity of FSC. The origin of the experimentally observed S-shape is investigated via calculation of form factors and established to be due to size-dependent interference effects that differ for the forward and side scattered light. Finally, by analyzing emulsions composed of mixtures of bipolar and radial droplets at rates of up to 10,000 droplets per second, we demonstrate that flow cytometry permits precise determination of the percentage of radial droplets within the mixture with a coefficient of determination of 0.98 (as validated by optical microscopy). Overall, the results presented in this paper demonstrate that flow cytometry provides a promising approach for high throughput quantification of the internal configurations of LC emulsion microdroplets. Because large numbers of droplets can be characterized, it enables statistically robust analyses of LC droplets. The methodology also appears promising for quantification of chemical and biological assays based on adsorbate-induced ordering transitions within LC droplets.
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Sustained improvement of gas exchange and lung mechanics by vaporized perfluorocarbon inhalation in piglet acute lung injury model.
Clin Respir J
PUBLISHED: 08-27-2013
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New methods for perfluorocarbon (PFC) application have been proposed which include aerosolization and vaporization. However, the experimental documentation of efficacy of vaporization of PFC in the treatment of acute respiratory distress syndrome (ARDS) is still lacking.
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p85-RhoGDI2, a novel complex, is required for PSGL-1-induced ?1 integrin-mediated lymphocyte adhesion to VCAM-1.
Int. J. Biochem. Cell Biol.
PUBLISHED: 06-03-2013
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P-selectin glycoprotein ligand-1 and ?1 integrin play essential roles in T cell trafficking during inflammation. E-selectin and vascular cell adhesion molecule-1 are their ligands expressed on inflammation-activated endothelium. During the tethering and rolling of lymphocytes on endothelium, P-selectin glycoprotein ligand-1 binds E-selectin and induces signals. Subsequently, ?1 integrin is activated and mediates stable adhesion. However, the intracellular signal pathways from PSGL-1 to ?1 integrin have not yet been fully understood. Here, we find that p85, a regulatory subunit of phosphoinositide 3-kinase, forms a novel complex with Rho-GDP dissociation inhibitor-2, a lymphocyte-specific RhoGTPases dissociation inhibitor. Phosporylations of the p85-bound Rho-GDP dissociation inhibitor-2 on 130 and 153 tyrosine residues by c-Abl and Src were required for the complex to be recruited to P-selectin glycoprotein ligand-1 and thereby regulate ?1 integrin-mediated T cell adhesion to vascular cell adhesion molecule-1. Both shRNAs to Rho-GDP dissociation inhibitor-2 and p85 and over-expression of Rho-GDP dissociation inhibitor-2 Y130F and Y153F significantly reduced the above-mentioned adhesion. Although Rho-GDP dissociation inhibitor-2 in the p85-Rho-GDP dissociation inhibitor-2 complex was also phosphorylated on 24 tyrosine residue by Syk, the phosphorylation is not required for the adhesion. Taken together, we find that specific phosphorylations on 130 and 153 tyrosine residues of p85-bound Rho-GDP dissociation inhibitor-2 are pivotal for P-selectin glycoprotein ligand-1-induced ?1 integrin-mediated lymphocyte adhesion to vascular cell adhesion molecule-1. This will shed new light on the mechanisms that connect leukocyte initial rolling with subsequent adhesion.
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Nematic-field-driven positioning of particles in liquid crystal droplets.
Phys. Rev. Lett.
PUBLISHED: 04-26-2013
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Common nematic oils, such as 5CB, experience planar anchoring at aqueous interfaces. When these oils are emulsified, this anchoring preference and the resulting topological constraints lead to the formation of droplets that exhibit one or two point defects within the nematic phase. Here, we explore the interactions of adsorbed particles at the aqueous interface through a combination of experiments and coarse-grained modeling, and demonstrate that surface-active particles, driven by elastic forces in the droplet, readily localize to these defect regions in a programmable manner. When droplets include two nanoparticles, these preferentially segregate to the two poles, thereby forming highly regular dipolar structures that could serve for hierarchical assembly of functional structures. Addition of sufficient concentrations of surfactant changes the interior morphology of the droplet, but pins defects to the interface, resulting in aggregation of the two particles.
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Multiple ray cluster rendering for interactive integral imaging system.
Opt Express
PUBLISHED: 04-24-2013
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In this paper, we present an efficient Computer Generated Integral Imaging (CGII) method, called multiple ray cluster rendering (MRCR). Based on the MRCR, an interactive integral imaging system is realized, which provides accurate 3D image satisfying the changeable observers positions in real time. The MRCR method can generate all the elemental image pixels within only one rendering pass by ray reorganization of multiple ray clusters and 3D content duplication. It is compatible with various graphic contents including mesh, point cloud, and medical data. Moreover, multi-sampling method is embedded in MRCR method for acquiring anti-aliased 3D image result. To our best knowledge, the MRCR method outperforms the existing CGII methods in both the speed performance and the display quality. Experimental results show that the proposed CGII method can achieve real-time computational speed for large-scale 3D data with about 50,000 points.
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Liquid crystal-based emulsions for synthesis of spherical and non-spherical particles with chemical patches.
J. Am. Chem. Soc.
PUBLISHED: 04-19-2013
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We report the use of liquid crystal (LC)-in-water emulsions for the synthesis of either spherical or non-spherical particles with chemically distinct domains located at the poles of the particles. The approach involves the localization of solid colloids at topological defects that form predictably at surfaces of water-dispersed LC droplets. By polymerizing the LC droplets displaying the colloids at their surface defects, we demonstrate formation of both spherical and, upon extraction of the mesogen, anisotropic composite particles with colloids located at either one or both of the poles. Because the colloids protrude from the surfaces of the particles, they also define organized, chemical patches with functionality controlled by the colloid surface.
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Value of 3-dimensional sonography for prenatal diagnosis of vertebral formation failure.
J Ultrasound Med
PUBLISHED: 03-26-2013
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The purposes of this study were to explore the value of 3-dimensional sonography for diagnosis of vertebral formation failure in the developing fetus and to formulate antenatal sonographic diagnostic criteria for suspected vertebral formation failure based on a comparison of sonographic characteristics of the disorder with normal sonographic findings and other imaging data.
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Antibacterial activity and cytocompatibility of Cu-Ti-O nanotubes.
J Biomed Mater Res A
PUBLISHED: 03-08-2013
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TiO2 nanotubes (NTs) have favorable biological properties, but the poor antibacterial activity limits their application especially in orthopedics fields. In this article, Cu-Ti-O nanotubes with different Cu contents are fabricated on sputtered TiCu films. Scanning electron microscopy reveals the NTs can be formed on sputtered TiCu films when the Cu content is less than 14.6 at %. X-ray photoelectron spectroscopy results indicate the NTs are consist of CuO mixed with TiO2 and the Cu content in NTs decreases dramatically compared with that in TiCu films. Biological experiments show that although these NTs have poor release antibacterial activity, their contact antibacterial activity has proven to be excellent, indicating the NT surface can effectively inhibit biomaterial-associated infections. The cytocompatibility of the NTs is closely related to the Cu content and when its content is relatively low (1.01 at %), there is no appreciable cytotoxicity. So Cu-Ti-O NTs with 1 at % Cu may be suitable to achieve proper antibacterial activity and desired cytocompatibility. The Cu-Ti-O NTs integrate the favorable antibacterial activity of Cu and excellent biological properties of TiO2 NTs therefore have potential applications in orthopedics, dentistry, and other biomedical fields. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
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Sonographic features of a juvenile polyp: a case report and literature review.
Clin Imaging
PUBLISHED: 02-18-2013
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Juvenile polyps are a rare form of gastrointestinal polyps and are generally diagnosed by colonoscopy or barium enema. In this article, we describe the case of a 3-year-old girl with a large juvenile polyp that was diagnosed by abdominal ultrasound. Ultrasound examination is necessary for children who pass dark red bloody stools either with or without abdominal pain. In addition, mechanical bowel preparation before ultrasonic testing is helpful to enable the detection of intraluminal lesions.
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c-Abl tyrosine kinase plays a critical role in ?2 integrin-dependent neutrophil migration by regulating Vav1 activity.
J. Leukoc. Biol.
PUBLISHED: 01-16-2013
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The recruitment and migration of neutrophils are critical for innate immunity and acute inflammatory responses. However, the mechanism that regulates the recruitment and migration of neutrophils has not been well characterized. We here reveal a novel function of c-Abl kinase in regulating neutrophil migration. Our results demonstrate that c-Abl kinase is required for neutrophil recruitment in vivo and migration in vitro, and the inhibition of c-Abl kinase activity has a significant impact on neutrophil migratory behavior. Moreover, c-Abl kinase activation depends on ?2 integrin engagement, and the activated c-Abl kinase further regulates actin polymerization and membrane protrusion dynamics at the extended leading edges during neutrophil migration. In addition, we identify the Rho GEF Vav1 as a major downstream effector of c-Abl kinase. The C-terminal SH3-SH2-SH3 domain and proline-rich region of Vav1 are required for its interaction with c-Abl kinase, and c-Abl kinase probably regulates the activity of Vav1 by direct phosphorylation at Tyr-267 in the DH domain. Together, these results indicate that c-Abl kinase plays a critical role in ?2 integrin-dependent neutrophil migration by regulating Vav1 activity.
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Nitric oxide in plants: the roles of ascorbate and hemoglobin.
PLoS ONE
PUBLISHED: 01-01-2013
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Ascorbic acid and hemoglobins have been linked to nitric oxide metabolism in plants. It has been hypothesized that ascorbic acid directly reduces plant hemoglobin in support of NO scavenging, producing nitrate and monodehydroascorbate. In this scenario, monodehydroascorbate reductase uses NADH to reduce monodehydroascorbate back to ascorbate to sustain the cycle. To test this hypothesis, rates of rice nonsymbiotic hemoglobin reduction by ascorbate were measured directly, in the presence and absence of purified rice monodehydroascorbate reductase and NADH. Solution NO scavenging was also measured methodically in the presence and absence of rice nonsymbiotic hemoglobin and monodehydroascorbate reductase, under hypoxic and normoxic conditions, in an effort to gauge the likelihood of these proteins affecting NO metabolism in plant tissues. Our results indicate that ascorbic acid slowly reduces rice nonsymbiotic hemoglobin at a rate identical to myoglobin reduction. The product of the reaction is monodehydroascorbate, which can be efficiently reduced back to ascorbate in the presence of monodehydroascorbate reductase and NADH. However, our NO scavenging results suggest that the direct reduction of plant hemoglobin by ascorbic acid is unlikely to serve as a significant factor in NO metabolism, even in the presence of monodehydroascorbate reductase. Finally, the possibility that the direct reaction of nitrite/nitrous acid and ascorbic acid produces NO was measured at various pH values mimicking hypoxic plant cells. Our results suggest that this reaction is a likely source of NO as the plant cell pH drops below 7, and as nitrite concentrations rise to mM levels during hypoxia.
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Lipid Raft Is Required for PSGL-1 Ligation Induced HL-60 Cell Adhesion on ICAM-1.
PLoS ONE
PUBLISHED: 01-01-2013
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P-selectin glycoprotein ligand-1 (PSGL-1) and integrins are adhesion molecules that play critical roles in host defense and innate immunity. PSGL-1 mediates leukocyte rolling and primes leukocytes for integrin-mediated adhesion. However, the mechanism that PSGL-1 as a rolling receptor in regulating integrin activation has not been well characterized. Here, we investigate the function of lipid raft in regulating PSGL-1 induced ?2 integrin-mediated HL-60 cells adhesion. PSGL-1 ligation with antibody enhances the ?2 integrin activation and ?2 integrin-dependent adhesion to ICAM-1. Importantly, with the treatment of methyl-?-cyclodextrin (M?CD), we confirm the role of lipid raft in regulating the activation of ?2 integrin. Furthermore, we find that the protein level of PSGL-1 decreased in raft fractions in M?CD treated cells. PSGL-1 ligation induces the recruitment of spleen tyrosine kinase (Syk), a tyrosine kinase and Vav1 (the pivotal downstream effector of Syk signaling pathway involved in cytoskeleton regulation) to lipid raft. Inhibition of Syk activity with pharmacologic inhibitor strongly reduces HL-60 cells adhesion, implicating Syk is crucial for PSGL-1 mediated ?2 integrin activation. Taken together, we report that ligation of PSGL-1 on HL-60 cells activates ?2 integrin, for which lipid raft integrity and Syk activation are responsible. These ?ndings have shed new light on the mechanisms that connect leukocyte initial rolling with subsequent adhesion.
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c-Abl Kinase Is a Regulator of ?v?3 Integrin Mediated Melanoma A375 Cell Migration.
PLoS ONE
PUBLISHED: 01-01-2013
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Integrins are heterodimeric transmembrane receptors that physically link the extracellular matrix (ECM) to the intracellular actin cytoskeleton, and are also signaling molecules that transduce signals bi-directionally across the plasma membrane. Integrin regulation is essential for tumor cell migration in response to growth factors. c-Abl kinase is a nonreceptor tyrosine kinase and is critical for signaling transduction from various receptors. Here we show that c-Abl kinase is involved in A375 cell migration mediated by ?v?3 integrin in response to PDGF stimulation. c-Abl kinase colocalizes with ?v?3 integrin dynamically and affects ?v?3 integrin affinity by regulating its cluster. The interaction between c-Abl kinase and ?v?3 integrin was dependent on the activity of c-Abl kinase induced by PDGF stimulation, but was not dependent on the binding of ?v?3 integrin with its ligands, suggesting that c-Abl kinase is not involved in the outside-in signaling of ?v?3 integrin. Talin head domain was required for the interaction between c-Abl kinase and ?v?3 integrin, and the SH3 domain of c-Abl kinase was involved in its interaction with talin and ?v?3 integrin. Taken together, we have uncovered a novel and critical role of c-Abl kinase in ?v?3 integrin mediated melanoma cell migration.
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Comprehensive kinetic and thermodynamic study of the reactions of CO2(aq) and HCO3(-) with monoethanolamine (MEA) in aqueous solution.
J Phys Chem A
PUBLISHED: 11-29-2011
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The temperature dependence of the reversible reaction between CO(2)(aq) and monoethanolamine (MEA) has been investigated using stopped-flow spectrophotometry by following the pH changes during the reactions with colored acid-base indicators. Multivariate global analysis of both the forward and backward kinetic measurements for the reaction of CO(2)(aq) with MEA yielded the rate and equilibrium constants, including the protonation constant of MEA carbamate, for the temperature range of 15-45 °C. Analysis of the rate and equilibrium constants in terms of the Arrhenius, Eyring, and vant Hoff relationships gave the relevant thermodynamic parameters. In addition, the rate and equilibrium constants for the slow, reversible reaction of bicarbonate with MEA are reported at 25.0 °C. At high pH, reactions of the amine with CO(2) and with bicarbonate are significant.
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Kinetics of the reversible reaction of CO2(aq) with ammonia in aqueous solution.
J Phys Chem A
PUBLISHED: 05-20-2011
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The kinetics of the interactions of aqueous ammonia with aqueous carbon dioxide/carbonate species has been investigated using stopped-flow techniques by monitoring the pH changes via indicators. The reactions include the reversible formation of ammonium carbamate/carbamic acid. A complete reaction mechanism has been established, and the temperature dependence of all rate and equilibrium constants including the protonation constant of the amine between 15 and 45 °C are reported and analyzed in terms of Arrhenius, Eyring, and vant Hoff relationships.
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Nanoporous bimetallic Pt-Au alloy nanocomposites with superior catalytic activity towards electro-oxidation of methanol and formic acid.
Nanoscale
PUBLISHED: 02-11-2011
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We present a facile route to fabricate novel nanoporous bimetallic Pt-Au alloy nanocomposites by dealloying a rapidly solidified Al(75)Pt(15)Au(10) precursor under free corrosion conditions. The microstructure of the precursor and the as-dealloyed sample was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray (EDX) analysis. The Al(75)Pt(15)Au(10) precursor is composed of a single-phase Al(2)(Au,Pt) intermetallic compound, and can be fully dealloyed in a 20 wt.% NaOH or 5 wt.% HCl aqueous solution. The dealloying leads to the formation of the nanoporous Pt(60)Au(40) nanocomposites (np-Pt(60)Au(40) NCs) with an fcc structure. The morphology, size and crystal orientation of grains in the precursor can be conserved in the resultant nanoporous alloy. The np-Pt(60)Au(40) NCs consist of two zones with distinct ligament/channel sizes and compositions. The formation mechanism of these np-Pt(60)Au(40) NCs can be rationalized based upon surface diffusion of more noble elements and spinodal decomposition during dealloying. Electrochemical measurements demonstrate that the np-Pt(60)Au(40) NCs show superior catalytic activity towards the electro-oxidation of methanol and formic acid in the acid media compared to the commercial JM-Pt/C catalyst. This material can find potential applications in catalysis related areas, such as direct methanol or formic acid fuel cells. Our findings demonstrate that dealloying is an effective and simple strategy to realize the alloying of immiscible systems under mild conditions, and to fabricate novel nanostructures with superior performance.
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Leptin receptor (Lepr) is a negative modulator of bone mechanosensitivity and genetic variations in Lepr may contribute to the differential osteogenic response to mechanical stimulation in the C57BL/6J and C3H/HeJ pair of mouse strains.
J. Biol. Chem.
PUBLISHED: 09-17-2010
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This study investigated the role of leptin receptor (Lepr) signaling in determining the bone mechanosensitivity and also evaluated whether differences in the Lepr signaling may contribute to the differential osteogenic response of the C57BL/6J (B6) and C3H/HeJ (C3H) pair of mouse strains to mechanical stimuli. This study shows that a loading strain of ?2,500 ??, which was insufficient to produce a bone formation response in B6 mice, significantly increased bone formation parameters in leptin-deficient ob(-)/ob(-) mice and that a loading strain of ?3,000 ?? also yielded greater osteogenic responses in Lepr-deficient db(-)/db(-) mice than in wild-type littermates. In vitro, a 30-min steady shear stress increased [(3)H]thymidine incorporation and Erk1/2 phosphorylation in ob(-)/ob(-) osteoblasts and db(-)/db(-) osteoblasts much greater than those in corresponding wild-type osteoblasts. The siRNA-mediated suppression of Lepr expression in B6 osteoblasts enhanced (but in osteoblasts of C3H (the mouse strain with poor bone mechanosensitivity) restored) their anabolic responses to shear stress. The Lepr signaling (leptin-induced Jak2/Stat3 phosphorylation) in C3H osteoblasts was higher than that in B6 osteoblasts. One of the three single nucleotide polymorphisms in the C3H Lepr coding region yielded an I359V substitution near the leptin binding region, suggesting that genetic variation of Lepr may contribute to a dysfunctional Lepr signaling in C3H osteoblasts. In conclusion, Lepr signaling is a negative modulator of bone mechanosensitivity. Genetic variations in Lepr, which result in a dysfunctional Lepr signaling in C3H mice, may contribute to the poor osteogenic response to loading in C3H mice.
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Reversible organogels triggered by dynamic K+ binding and release.
J Colloid Interface Sci
PUBLISHED: 07-24-2010
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In this study, a new lipophilic guanosine derivative was synthesized as an organogelator. The self-aggregation behavior of this organogelator was investigated by NMR, XRD and AFM. In solution, the lipophilic guanosine derivative can form a stable ribbon-like structure through NH(1)-N(7) and NH(2)-O(6) hydrogen bonds. However, gelation would occur in some aprotic solvents after the concentration reached a definite value. More interesting, the ribbon-like structure was able to change to G-quartets in the presence of K(+), which led to the transformation from a gel to a sol. Upon the addition of the cryptand [2.2.2], which can efficiently complex with K(+), G-quartets reverted to the original ribbon-like structure and the gel recovered. Subsequently, upon the addition of acids, K(+) was released from the cryptate with the transformation of gel-to-sol simultaneously. Finally, upon the addition of bases which deprotonated [H(+) ? 2.2.2], the liberated cryptand [2.2.2] recaptured K(+) and the gel was regenerated again. This process of interconversion between G-ribbon 1(n) and octamer 1(8)·K(+) was well monitored by circular dichroism spectra.
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Spin squeezing, negative correlations, and concurrence in the quantum kicked top model.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 07-13-2010
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We study spin squeezing, negative correlations, and concurrence in the quantum kicked top model. We prove that the spin squeezing and negative correlations are equivalent for spin systems with only symmetric Dicke states populated. We numerically analyze spin squeezing parameters and concurrence in this model and find that the maximal spin squeezing direction, which refers to the minimal pairwise correlation direction, is strongly influenced by quantum chaos. Entanglement (spin squeezing) sudden death and sudden birth occur alternatively for the periodic and quasiperiodic cases, while only entanglement (spin squeezing) sudden death is found for the chaotic case.
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PI3K is involved in L-selectin- and PSGL-1-mediated neutrophil rolling on E-selectin via F-actin redistribution and assembly.
J. Cell. Biochem.
PUBLISHED: 06-22-2010
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L-selectin and P-selectin glycoprotein ligand-1 (PSGL-1) are adhesion molecules that play critical roles in neutrophil rolling during inflammation and lymphocyte homing. On the other hand they also function as signaling receptors to induce cytoskeleton changes. The present study is to investigate the signaling kinases responsible for the F-actin changes mediated by L-selectin and PSGL-1 during neutrophil rolling on E-selectin. Western blot analysis demonstrated that PI3K activation, peaking within 5 min, was induced by ligation of L-selectin and PSGL-1 with E-selectin, and that Vav1 (the pivotal downstream effector of PI3K signaling pathway involved in cytoskeleton regulation) was recruited to the membrane and tyrosine-phosphorylated, depending on PI3K. Furthermore, the F-actin redistribution and assembly mediated by ligation with E-selectin were blocked by LY294002, a PI3K specific inhibitor. Additional experiments showed that PI3K activity was involved in neutrophil rolling on E-selectin. However, Syk/Zap70, the well-known upstream kinase of PI3K, was not involved in this event. These data suggest that PI3K is required for the F-actin-based cytoskeleton changes during neutrophil rolling on E-selectin, which may consequently regulate the rolling event.
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Production and identification of wheat-Agropyron cristatum 6P translocation lines.
Planta
PUBLISHED: 03-14-2010
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The narrow genetic background of wheat is the primary factor that has restricted the improvement of crop yield in recent years. The kernel number per spike is the most important factor of the many potential characteristics that determine wheat yield. Agropyron cristatum (L.) Gaertn., a wild relative of wheat, has the characteristics of superior numbers of florets and kernels per spike, which are controlled by chromosome 6P. In this study, the wheat-A. cristatum disomic addition and substitution lines were used as bridge materials to produce wheat-A. cristatum 6P translocation lines induced by gametocidal chromosomes and irradiation. The results of genomic in situ hybridization showed that the frequency of translocation induced by gametocidal chromosomes was 5.08%, which was higher than the frequency of irradiated hybrids (2.78%) and irradiated pollen (2.12%). The fluorescence in situ hybridization results of the translocation lines showed that A. cristatum chromosome 6P could be translocated to wheat ABD genome, and the recombination frequency was A genome > B genome > D genome. The alien A. cristatum chromosome 6P was translocated to wheat homoeologous groups 1, 2, 3, 5 and 6. We obtained abundant translocation lines that possessed whole-arm, terminal, segmental and intercalary translocations. Three 6PS-specific and four 6PL-specific markers will be useful to rapidly identify and trace the translocated fragments. The different wheat-A. cristatum 6P translocation lines obtained in this study can provide basic materials for analyzing the alien genes carried by chromosome 6P. The translocation line WAT33-1-3 and introgression lines WAI37-2 and WAI41-1, which had significant characteristics of multikernel (high numbers of kernels per spike), could be utilized as novel germplasms for high-yield wheat breeding.
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Polycyclic aromatic hydrocarbon removal from contaminated soils using fatty acid methyl esters.
Chemosphere
PUBLISHED: 01-18-2010
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In this study, solubilization of PAHs from a manufactured gas plant (MGP) soil and two artificially spiked soils using fatty acid methyl esters (FAME) was investigated. PAH removals from both the MGP and the spiked soils by FAME, methanol, soybean oil, hydroxypropyl-beta-cyclodextrin, Triton X-100, and Tween 80 were compared. The effect of FAME:MGP soil ratios on PAH removals was also investigated. Results showed that the FAME mixture synthesized by our lab was more efficient than the cyclodextrin and the two surfactants used for PAH removal from the spiked soils with individual PAH concentrations of 200 and 400 mg kg(-1). However, the difference among three PAH removals by the FAME, soybean oil and methanol was not quite pronounced. The FAME synthesized and market biodiesel exhibited better performance for PAH removals (46% and 35% of total PAH) from the weathered contaminated MGP soil when compared with the other agents (0-31%). Individual PAH removals from the weathered MGP soil were much lower than those from the spiked soils. The percentages of total PAH removals from the MGP soil were 59%, 46%, and 51% for the FAME:MGP soil ratios of 1:2, 1:1, and 2:1, respectively. These results showed that the FAME could be a more attractive alternative to conventional surfactants in ex situ washing of PAH-contaminated soils.
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Ground-state properties of the two-site Hubbard-Holstein model: an exact solution.
J Phys Condens Matter
PUBLISHED: 09-23-2009
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We study the two-site Hubbard-Holstein model by using an extended phonon coherent state. For the nontrivial singlet bipolarons, the double occupancy probability, the fidelity and the entanglement entropy are calculated to characterize the ground-state properties in both two-site and single-site bipolaron-dominated regimes. We use the localized minimum of the fidelity to define a crossover and plot the bipolaron phase diagram, which separates the large and small entanglement region. Furthermore, the relation between the bipolaron entanglement and the correlation functions demonstrates that the large entanglement corresponds to the large magnitude of lattice deformations induced by electrons.
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Many-body reduced fidelity susceptibility in Lipkin-Meshkov-Glick model.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 07-02-2009
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We study the reduced fidelity susceptibility chi(r) for an M -body subsystem of an N -body Lipkin-Meshkov-Glick model with tau=M/N fixed. The reduced fidelity susceptibility can be viewed as the response of subsystem to a certain parameter. In noncritical region, the inner correlation of the system is weak, and chi(r) behaves similar with the global fidelity susceptibility chi(g), the ratio eta=chi(r)/chi(g) depends on tau but not on N. However, at the critical point, the inner correlation tends to be divergent, and we find chi(r) approaches chi(g) with increasing the N. It is interesting to note that, eta=1 in the thermodynamic limit, which means the susceptibilities of the local and global system are the same. Finally, we make numerical computations, and they are in perfect agreement with the analytical predictions.
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Regulatory T cells contribute to the immunoregulatory effect on graft versus host reaction after liver transplantation in donor-dominant one-way MHC matching rats.
Transpl. Immunol.
PUBLISHED: 05-15-2009
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Acute graft-versus-host disease following liver transplantation (LTx-aGVHD) poses a major diagnostic and therapeutic challenge, and the mortality rate is as high as 85%. Even the liver contains large numbers of lymphoid cells in the parenchyma and surgical damage of liver transplantation would induce an immunosuppressive, the incidence of LTx-aGVHD is just approximately 1-2%. CD4(+)CD25(+)regulatory T (Treg) cells have recently been shown to suppress proliferative responses of CD4(+)CD25(-)T cells to alloantigenic stimulation in vitro and are required for ex vivo tolerization of donor T cells, which results in their reduced potential to induce aGVHD after bone marrow transplantation. To investigate the role of Treg in LTx-aGVHD, we compared the proportional frequency of Treg in syngeneic liver transplantation recipients (sLT group), semiallogeneic liver transplantation recipients (Semi-LT group), LTx-aGVHD induced recipients (LTx-aGVHD group) and healthy controls. Here we show that replacement of (LewisXBN)F1 liver by Lewis liver alone in Semi-LT group was not sufficient to induce aGVHD, and all recipients grew in a normal pattern as the syngeneic LT from Lewis to Lewis rat. However, when 4 x 10(8) of donor splenocytes were transferred simultaneously with LT, the morbidity of lethal aGVHD were 100%. A relative stable percentage of Treg, defined as CD4, CD25 and Foxp3, was detected in peripheral blood mononuclear cells (PBMCs) of sLT group compared with healthy controls. In early time after transplantation, no significantly change of Treg population was observed in these recipients after semiallogeneic liver transplantation in comparison with healthy controls (P>0.05). However, Treg levels showed a relative increase 4 days after transplantation. Especially on 12th and 16th day after transplantation, there was significantly increased proportion of Treg cells compared with healthy controls (P<0.05). The present of Treg decreased progressively in LTx-aGVHD group, which was significantly lower than group 1 and group 2 on the 12th and 16th day after liver transplantation (p<0.05). In conclusion, recipients in semi-LT group harbor an increased percentage of Treg in peripheral blood compared with controls. Treg have an immunoregulatory effect on graft versus host reaction after liver transplantation. Additional donor splenocyte transplanted with the liver provoke the development of aGVHD after liver transplantation, and reversed the change of Treg in PBMCs as in Semi-LT group, which destroy the balance between Treg and conventional effector T cells which determine the outcome of aGVHD after liver transplantation.
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Spin squeezing as an indicator of quantum chaos in the Dicke model.
Phys Rev E Stat Nonlin Soft Matter Phys
PUBLISHED: 04-29-2009
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We study spin squeezing, an intrinsic quantum property, in the Dicke model without the rotating-wave approximation. We show that the spin squeezing can reveal the underlying chaotic and regular structures in phase space given by a Poincaré section, namely, it acts as an indicator of quantum chaos. Spin squeezing vanishes after a very short time for an initial coherent state centered in a chaotic region, whereas it persists over a longer time for the coherent state centered in a regular region of the phase space. We also study the distribution of the mean spin directions when quantum dynamics takes place. Finally, we discuss relations among spin squeezing, bosonic quadrature squeezing, and two-qubit entanglement in the dynamical processes.
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Kinetics and mechanism of carbamate formation from CO2(aq), carbonate species, and monoethanolamine in aqueous solution.
J Phys Chem A
PUBLISHED: 04-03-2009
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Removal of carbon dioxide from fossil-based power generation is a potentially useful technique for the reduction of greenhouse gas emissions. Reversible interaction with aqueous amine solutions is most promising. In this process, the formation of carbamates is an important reaction of carbon dioxide. In this contribution, a detailed molecular reaction mechanism for the carbamate formation between MEA (monoethanolamine) and dissolved CO(2) as well as carbonate species in aqueous solution is presented. There are three parallel, reversible reactions of the free amine with CO(2), carbonic acid, and the bicarbonate ion; the relative importance of the three paths is strongly pH dependent. Kinetic and equilibrium measurements are based on (1)H NMR and stopped-flow measurements with rate constants, equilibrium constants, and protonation constants being reported.
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The discovery of HNPC-A3066: a novel strobilurin acaricide.
Pest Manag. Sci.
PUBLISHED: 04-03-2009
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Although more than ten strobilurin analogues have been commercialized since 1996 as fungicides, only one was available as an acaricide as of 2003. To search for novel strobilurin analogues with unique biological activities, a synthetic screening programme was carried out.
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Modulating the behaviors of C3A cells via surface charges of polyelectrolyte multilayers.
Carbohydr Polym
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The purpose of this study was to evaluate in vitro how the modulating surface charges of materials influenced the behaviors of hepatocytes. Cells of a human hepatocyte cell line, C3A, which have been used in a clinically tested bioartificial liver, were conducted as cell models. Polyelectrolyte multilayers (PEMs) of poly-L-lysine and alginate biopolymers were fabricated and then the zeta potential was assessed. Protein adsorption study showed that fibrinogen deposition could be modulated via tuning the terminal layer and the surface charges of PEMs. Furthermore, through observing the cellular morphology, viability, functional protein analysis and gene expression, we found that the behavior of C3A cells could be modulated via tuning of surface charges on PEMs, which was different from that via grafting functional groups on PEMs. It suggested that the PEMs with different charges could be used in vitro to manipulate cell behaviors to improve upon the design of tissue engineering.
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Toward the understanding of chemical absorption processes for post-combustion capture of carbon dioxide: electronic and steric considerations from the kinetics of reactions of CO2(aq) with sterically hindered amines.
Environ. Sci. Technol.
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The present study reports (a) the determination of both the kinetic rate constants and equilibrium constants for the reaction of CO(2)(aq) with sterically hindered amines and (b) an attempt to elucidate a fundamental chemical understanding of the relationship between the amine structure and chemical properties of the amine that are relevant for postcombustion capture of CO(2) (PCC) applications. The reactions of CO(2)(aq) with a series of linear and methyl substituted primary amines and alkanolamines have been investigated using stopped-flow spectrophotometry and (1)H NMR measurements at 25.0 °C. The specific mechanism of absorption for each of the amines, that is CO(2) hydration and/or carbamate formation, is examined and, based on the mechanism, the kinetic and equilibrium constants for the formation of carbamic acid/carbamates, including protonation constants of the carbamate, are reported for amines that follow this pathway. A Brønsted correlation relating the kinetic rate constants and equilibrium constants for the formation of carbamic acid/carbamates with the protonation constant of the amine is reported. Such a relationship facilitates an understanding of the effects of steric and electronic properties of the amine toward its reactivity with CO(2). Further, such relationships can be used to guide the design of new amines with improved properties relevant to PCC applications.
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Matrix stiffness in three-dimensional systems effects on the behavior of C3A cells.
Artif Organs
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The purpose of this study was to evaluate in vitro how the modulation of stiffness in a three-dimensional (3D) system independently influenced the behaviors of hepatocytes. Cells of a human hepatocyte cell line, C3A, which have been used in a clinically tested bioartificial liver support system, were conducted as cell models. Using a 3D system of "mechanically tunable" alginate hydrogels, matrix stiffness was modeled by corresponding to values in normal and fibrotic livers. Through observing the cellular morphology, viability, functional protein analysis, and gene expression, the effect of the 3D matrix stiffness on C3A cells was investigated. When cultured in stiff hydrogels (12?Kpa), C3A cells adopt a growth arrested and dedifferentiated phenotype, whereas in soft hydrogels (1?Kpa), they remain differentiated phenotype. The behavior of C3A cells can be modulated via independent tuning of mechanical stimuli in the 3D alginate hydrogels, which is different from that in the two-dimensional (2D) systems. The results indicate the importance of matrix stiffness choice for liver tissue engineering.
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Value of the fetal plantar shape in prenatal diagnosis of talipes equinovarus.
J Ultrasound Med
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The purpose of this study was to evaluate the value of the fetal plantar shape in prenatal diagnosis of talipes equinovarus.
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Toward rational design of amine solutions for PCC applications: the kinetics of the reaction of CO2(aq) with cyclic and secondary amines in aqueous solution.
Environ. Sci. Technol.
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The kinetics of the fast reversible carbamate formation reaction of CO(2)(aq) with a series of substituted cyclic secondary amines as well as the noncyclic secondary amine diethanolamine (DEA) has been investigated using the stopped-flow spectrophotometric technique at 25.0 °C. The kinetics of the slow parallel reversible reaction between HCO(3)(-) and amine has also been determined for a number of the amines by (1)H NMR spectroscopy at 25.0 °C. The rate of the reversible reactions and the equilibrium constants for the formation of carbamic acid/carbamate from the reactions of CO(2) and HCO(3)(-) with the amines are reported. In terms of the forward reaction of CO(2)(aq) with amine, the order with increasing rate constants is as follows: diethanolamine (DEA) < morpholine (MORP) ~ thiomorpholine (TMORP) < N-methylpiperazine (N-MPIPZ) < 4-piperidinemethanol (4-PIPDM) ~ piperidine (PIPD) < pyrrolidine (PYR). Both 2-piperidinemethanol (2-PIPDM) and 2-piperidineethanol (2-PIPDE) do not form carbamates. For the carbamate forming amines a Brønsted correlation relating the protonation constant of the amine to the carbamic acid formation rate and equilibrium constants at 25.0 °C has been established. The overall suitability of an amine for PCC in terms of kinetics and energy is discussed.
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Microenvironment of alginate-based microcapsules for cell culture and tissue engineering.
J. Biosci. Bioeng.
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As a type of 3D model, the technology of microencapsulation holds significant promise for tissue engineering and cell therapy due to its unique performance. The microenvironmental factors within microcapsules play an important role in influencing the behaviors of encapsulated cells. The aim of this review article is to give an overview on the construction of the microenvironmental factors, which include 3D space, physicochemical properties of alginate matrix, cell spheroids, nutritional status, and so on. Furthermore, we clarified the effect of microenvironmental factors on the behaviors of encapsulated cells and the methods about improving the microenvironment of microcapsules. This review will help to understand the interaction of the microenvironment and the encapsulated cells and lay a solid foundation for microcapsule-based cell therapy and tissue engineering.
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PI3K is involved in ?1 integrin clustering by PSGL-1 and promotes ?1 integrin-mediated Jurkat cell adhesion to fibronectin.
Mol. Cell. Biochem.
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P-selectin glycoprotein ligand-1 (PSGL-1) is involved in the initial step of lymphocyte homing by interacting with P- or E-selectins expressed on activated endothelium cells. Besides, it also functions as a receptor to induce signals that increase integrin affinity to ligands and mediate cell adhesion to endothelium. Integrin is required for the second step of lymphocyte homing, whose activation has been reported tightly regulated by inside-out signals triggered by chemokines or the shear-stress generated during lymphocyte rolling on endothelium. However, the relationship between PSGL-1-triggered signals and integrin activation is not clear. In this study, we demonstrated that PSGL-1 ligation induces ?1 integrin-mediated adhesion to fibronectin via regulation of both ?1 subunit clustering and conformation changes. Phosphoinositide 3-kinase (PI3K) is required for PSGL-1-induced ?1 integrin clustering which ultimately regulates ?1 integrin-mediated Jurkat cell adhesion to fibronectin. However, PI3K is not involved in the conformation changes or increases in the total expression of ?1 integrin. Taken together, we found a novel signal pathway, PSGL-1-PI3K-?1 integrin, demonstrating the cooperation between initial adhesion and subsequent arrest and stable adhesion.
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