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Find video protocols related to scientific articles indexed in Pubmed.
Light-Scattering Detection below the Level of Single Fluorescent Molecules for High-Resolution Characterization of Functional Nanoparticles.
ACS Nano
PUBLISHED: 10-13-2014
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Ultrasensitive detection and characterization of single nanoparticles (<100 nm) is important in nanotechnology and life sciences. Direct measurement of the elastically scattered light from individual nanoparticles represents the simplest and the most direct method for particle detection. However, the sixth-power dependence of scattering intensity on particle size renders very small particles indistinguishable from the background. Adopting strategies for single-molecule fluorescence detection in a sheathed flow, here we report the development of high sensitivity flow cytometry (HSFCM) that achieves real-time light-scattering detection of single silica and gold nanoparticles as small as 24 and 7 nm in diameter, respectively. This unprecedented sensitivity enables high-resolution sizing of single nanoparticles directly based on their scattered intensity. With a resolution comparable to that of TEM and the ease and speed of flow cytometric analysis, HSFCM is particularly suitable for nanoparticle size distribution analysis of polydisperse/heterogeneous/mixed samples. Through concurrent fluorescence detection, simultaneous insights into the size and payload variations of engineered nanoparticles are demonstrated with two forms of clinical nanomedicine. By offering quantitative multiparameter analysis of single nanoparticles in liquid suspensions at a throughput of up to 10?000 particles per minute, HSFCM represents a major advance both in light-scattering detection technology and in nanoparticle characterization.
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Enhanced Cycle Performance of Lithium-Sulfur Batteries Using a Separator Modified with a PVDF-C Layer.
ACS Appl Mater Interfaces
PUBLISHED: 10-03-2014
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High energy density Li-S batteries are highly attractive. However, their use in practical applications has been greatly affected by their poor cycle life and low rate performance, which can be partly attributed to the dissolution of polysulfides from the S cathode and their migration to the Li anode through the separator. While much effort has been devoted to designing the structure of the S cathodes for suppressing the dissolution of polysulfides, relatively little emphasis has been placed on modifying the separator. Herein, we demonstrate a new approach for modifying the separator with a polyvinylidene fluoride-carbon (PVDF-C) layer, where the polysulfides generated in the Li-S cells can be localized on the cathode side. Li-S batteries based on the novel separator and a cathode prepared by the simple mixing of a S powder and super P have delivered discharge capacities of 918.6 mAh g(-1), 827.2 mAh g(-1), and 669.1 mAh g(-1) after 100, 200, and 500 cycles, respectively, at a discharge rate of 0.5 C. Even under current densities of up to 5 C, the cells were able to retain a discharge capacity of 393 mAh g(-1), thereby demonstrating an excellent high rate performance and stability. The exceptional electrochemical performance could be attributed to the intense adsorption capability of the micropores, presence of C-C double bonds, and conductivity of the C network in the PVDF-C layer. This economical and simple strategy to overcome the polysulfide dissolution issues provides a commercially feasible method for the construction of Li-S batteries.
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[Rhino-orbito-cerebral mucormycosis: report of 9 cases].
Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi
PUBLISHED: 09-23-2014
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To present the clinical characteristics and combination therapy of rhino-orbito-cerebral mucormycosis.
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S-1-Based versus capecitabine-based preoperative chemoradiotherapy in the treatment of locally advanced rectal cancer: a matched-pair analysis.
PLoS ONE
PUBLISHED: 09-02-2014
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The aim of this paper was to compare the efficacy and safety of S-1-based and capecitabine-based preoperative chemoradiotherapy regimens in patients with locally advanced rectal cancer through a retrospective matched-pair analysis.
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A predisposition for allergies predicts subsequent hypertension, dyslipidemia, and diabetes mellitus among patients with schizophrenia or bipolar disorder: a nationwide longitudinal study.
Schizophr. Res.
PUBLISHED: 08-10-2014
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Previous studies have shown that both severe mental disorders (schizophrenia and bipolar disorder) and atopic diseases were associated with an increased risk of metabolic syndrome. However, the role of atopy/the predisposition for allergies in the development of metabolic syndrome is still unknown among those with severe mental disorders.
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Liquid chromatography-mass spectrometry based serum peptidomic approach for renal clear cell carcinoma diagnosis.
J Pharm Biomed Anal
PUBLISHED: 08-02-2014
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Serum peptidomic approach was applied to investigate the peptidomic signature and discover the clinical biomarkers and biomarker patterns for RCC patients. The holistic orthogonal partial least-squares-discriminant analysis (OPLS-DA) based on qualified profile data successfully classified RCC patients from healthy controls, showing 100% sensitivity and specificity. Following critical criteria, several peptides presenting significant differences in serum level were picked out. The unsupervised hierarchical cluster analysis on those peptides was performed, showing 100% sensitivity and 93.3% specificity for RCC diagnosis regarding the present samples. Besides, receiver-operating characteristic (ROC) analysis was applied on single peptide biomarkers, with four peptides showing excellent predictive power. Among them, IYQLNSKLV and AGISMRSGDSPQD are reported for the first time for cancer detection.
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Thermal diffusion desorption for the comprehensive analysis of organic compounds.
Anal. Chem.
PUBLISHED: 06-10-2014
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Comprehensive analysis of organic compounds is crucial yet challenging considering that information on elements, fragments, and molecules is unavailable simultaneously by current analytical techniques. Additionally, many compounds are insoluble or only dissolve in toxic solvents. A solvent- and matrix-free strategy has been developed which allows the organic compound analyzed in its original form. It utilizes thermal diffusion desorption with the solid analyte irradiated with high energy laser. It is capable of providing explicit elemental, fragmental, and molecular information simultaneously for a variety of organic compounds. Thermal diffusion desorption has many advantages compared to the electrospray and MALDI techniques. The protons that form the protonated molecular ions originate from the analyte itself. All the elements and fragments are also derived from the analyte itself, which provides abundant information and expedites the identification of organic compounds.
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[Root exudates and soil microbes in three Picea asperata plantations with different stand ages].
Ying Yong Sheng Tai Xue Bao
PUBLISHED: 05-17-2014
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This study investigated the dynamics of in situ root exudates and soil microbial composition among three Picea asperata plantations with different stand ages (9, 13 and 31 a) in Miyaluo, west Sichuan, China. The results showed that the secretion rates of root exudation per fine biomass, length, surface area and tip were significantly different among the three plantations with different stand ages. The secretion rate of root exudation was the highest in the 9-year-old plantation stand. The root activity of P. asperata was the weakest in the 13-year-old plantation stand. Besides, soil microbial biomass C (MBC) and N (MBN) between rhizosphere and non-rhizosphere soils were significantly different among the three plantation stands. MBC and MBN contents of rhizosphere soil gradually increased with stand ages, while those of non-rhizosphere soil were the largest in the 13-year-old plantation stand. The phospholipid fatty acids (PLFAs) of bacteria, fungi, actinomycetes and their summation in rhizosphere soil presented a trend of high-low-high with stand ages. The opposite pattern was found in the PLFAs of bacteria, fungi, the summation of PLFA, and the ratio of fungi number to bacteria in non-rhizosphere soil. It is suggested that root exudates might have a positive rhizosphere effect on soil microbial biomass C, N and PLFAs of functional groups.
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Metabolomic analysis reveals a unique urinary pattern in normozoospermic infertile men.
J. Proteome Res.
PUBLISHED: 05-14-2014
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Normozoospermic infertility has become a common and important health problem worldwide. We designed this metabolomic case-control study to investigate the possible mechanism and urinary biomarkers of normozoospermic infertility. Normozoospermic infertile cases (n = 71) and fertile controls (n = 47) were recruited. A urinary metabolome pattern could discriminate normozoospermic infertile cases from fertile controls. A total of 37 potential biomarkers were identified; these have functionally important roles in energy production, antioxidation, and hormone regulation in spermatogenesis. This gave rise to a combined biomarker pattern of leukotriene E4, 3-hydroxypalmitoylcarnitine, aspartate, xanthosine, and methoxytryptophan pointing to a diagnostic capability (AUC = 0.901, sensitivity = 85.7%, and specificity = 86.8%) in a ROC model; these markers may highlight keynote events of normozoospermic infertility. Stalled medium- and long-chain fatty acid metabolism with improved ketone body metabolism, plus decreased levels of malate and aspartate could result in citrate cycle alterations via a malate-aspartate shuttle in ATP generation in spermatogenesis. Inhibitory alterations in the normal hormone-secreting activity in spermatogenesis were suggested in normozoospermic infertility. Folate deficiency and oxidative stress may jointly impact infertile patients. The disruption of eicosanoid metabolism and xanthine oxidase system, which were tightly associated with energy metabolism and oxidative stress, was also a potential underlying mechanism. In addition, depression might be associated with normozoospermic infertility via neural activity-related metabolites. This study suggests that the urinary metabolome can be used to differentiate normozoospermic infertile men from fertile individuals. Potential metabolic biomarkers derived from these analyses might be used to diagnose what remains a somewhat idiopathic condition and provide functional insights into its pathogenesis.
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Effects of ?3- and ?6-polyunsaturated fatty acids on RANKL-induced osteoclast differentiation of RAW264.7 cells: a comparative in vitro study.
Nutrients
PUBLISHED: 04-30-2014
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Polyunsaturated fatty acids (PUFAs) have been reported to have an anabolic effect on bone in vivo, but comparative studies to identify inhibitors of osteoclast formation amongst ?3- and ?6-PUFAs are still lacking. Here we assessed the effects of the ?3-PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and the ?6-PUFAs, arachidonic acid (AA) and ?-linolenic acid (GLA) on a RAW264.7 osteoclast differentiation model. The effects of PUFAs on RANKL-induced osteoclast formation were evaluated by counting tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells. PUFAs significantly inhibited RANKL-induced osteoclast formation in a dose-dependent manner with AA- and DHA-mediated inhibition being the strongest. Furthermore, RANKL-induced mRNA- and protein expression of the key osteoclastogenic genes cathepsin K and TRAP were inhibited by AA and more potently by DHA. Owing to the attenuated osteoclastogenesis by DHA and AA, actin ring formation and bone resorptive activity of these cells as evaluated on bone-mimetic plates were severely compromised. Hence, of the tested PUFAs, AA and DHA were found to be the most effective in inhibiting RANKL-induced osteoclast formation with the latter providing the strongest inhibitory effects. Collectively, the data indicates that these PUFAs may play an important role in regulating bone diseases characterized by excessive osteoclast activity.
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Altitudinal Distribution Patterns of Soil Bacterial and Archaeal Communities Along Mt. Shegyla on the Tibetan Plateau.
Microb. Ecol.
PUBLISHED: 04-03-2014
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Unraveling the distribution patterns of plants and animals along the elevational gradients has been attracting growing scientific interests of ecologists, whether the microbial communities exhibit similar elevational patterns, however, remains largely less documented. Here, we investigate the biogeographic distribution of soil archaeal and bacterial communities across three vertical climate zones (3,106-4,479 m.a.s.l.) in Mt. Shegyla on the Tibetan Plateau, by combining quantitative PCR and high-throughput barcoded pyrosequencing approaches. Our results found that the ratio of bacterial to archaeal 16S rRNA gene abundance was negatively related with elevation. Acidobacteria dominated in the bacterial communities, Marine benthic group A dominated in the archaeal communities, and the relative abundance of both taxa changed significantly with elevation. At the taxonomic levels of domain, phylum, and class, more bacterial taxa than archaeal exhibited declining trend in diversity along the increasing elevational gradient, as revealed by Shannon and Faith's phylogenetic diversity indices. Unweighted UniFrac distance clustering showed that the bacterial communities from the mountainous temperate zone clustered together, whereas those from the subalpine cool temperate zone clustered together. However, the partitioning effect of elevational zones on the archaeal community was much weaker compared to that on bacteria. Redundancy analysis revealed that soil geochemical factors explained 58.3 % of the bacterial community variance and 75.4 % of the archaeal community variance. Taken together, we provide evidence that soil bacteria exhibited more apparent elevational zonation feature and decreased diversity pattern than archaea with increasing elevation, and distribution patterns of soil microbes are strongly regulated by soil properties along elevational gradient in this plateau montane ecosystem.
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Influence of the selective EDTA derivative phenyldiaminetetraacetic acid on the speciation and extraction of heavy metals from a contaminated soil.
Chemosphere
PUBLISHED: 02-14-2014
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The development of more selective chelators for the washing of heavy metal contaminated soil is desirable in order to avoid excessive dissolution of soil minerals. Speciation and mobility of Cu, Zn, Pb, and Ni in a contaminated soil washed with phenyldiaminetetraacetic acid (PDTA), a derivative of EDTA, were investigated by batch leaching test using a range of soil washing conditions followed by sequential extraction. With appropriate washing conditions, PDTA significantly enhanced extraction of Cu from the contaminated soil. The primary mechanisms of Cu extraction by PDTA were complexation-promoted dissolution of soil Cu and increased dissolution of soil organic matter (SOM). PDTA showed high selectivity for Cu(II) over soil component cations (Ca(II), Mg(II), Fe(III), Mn(II), Al(III)), especially at lower liquid-to-soil ratios under PDTA deficiency, thus avoiding unwanted dissolution of soil minerals during the soil washing process which can degrade soil structure and interfere with future land use. PDTA-enhanced soil washing increased the exchangeable fractions of Cu, Zn, and Pb and decreased their residual fractions, compared to their levels in unwashed soil.
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Urinary metabolome identifies signatures of oligozoospermic infertile men.
Fertil. Steril.
PUBLISHED: 02-11-2014
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To identify the differential urinary metabolic pattern of oligozoospermic infertile men and to determine the potential biomarkers indicative of infertility.
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Initial copper stress strengthens the resistance of soil microorganisms to a subsequent copper stress.
Microb. Ecol.
PUBLISHED: 02-07-2014
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To improve the prediction of essential ecosystem functioning under future environmental disturbances, it is of significance to identify responses of soil microorganisms to environmental stresses. In this study, we collected polluted soil samples from field plots with eight copper levels ranging from 0 to 3,200 mg Cu kg(-1) soil. Then, the soils with 0 and 3,200 mg Cu kg(-1) were selected to construct a microcosm experiment. Four treatments were set up including Cu0-C and Cu3200-C without further Cu addition, and Cu0-A and Cu3200-A with addition of 57.5 mg Cu kg(-1) soil. We measured substrate-induced respiration (SIR) and potential nitrification rate (PNR). Furthermore, the abundance of bacterial, archaeal 16S rRNA genes, ammonia-oxidizing bacteria and archaea amoA genes were determined through quantitative PCR. The soil microbial communities were investigated by terminal restriction fragment length polymorphism (T-RFLP). For the field samples, the SIR and PNR as well as the abundance of soil microorganisms varied significantly between eight copper levels. Soil microbial communities highly differed between the low and high copper stress. In the microcosm experiment, the PNR and SIR both recovered while the abundance of soil microorganisms varied irregularly during the 90-day incubation. The differences of microbial communities measured by pairwise Bray-Curtis dissimilarities between Cu0-A and Cu0-C on day 0 were significantly higher after subsequent stress than before. However, the differences of microbial communities between Cu3200-A and Cu3200-C on day 0 changed little between after subsequent stress and before. Therefore, initial copper stress could increase the resistance of soil microorganisms to subsequent copper stress.
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Abundance and community structure of ammonia-oxidizing Archaea and Bacteria in response to fertilization and mowing in a temperate steppe in Inner Mongolia.
FEMS Microbiol. Ecol.
PUBLISHED: 01-15-2014
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Based on a 6-year field trial in a temperate steppe in Inner Mongolia, we investigated the effects of nitrogen (N) and phosphorus (P) fertilization and mowing on the abundance and community compositions of ammonia-oxidizing Bacteria (AOB) and Archaea (AOA) upon early (May) and peak (August) plant growth using quantitative PCR (qPCR), terminal-restriction fragment length polymorphism (T-RFLP), cloning and sequencing. The results showed that N fertilization changed AOB community composition and increased AOB abundance in both May and August, but significantly decreased AOA abundance in May. By contrast, P fertilization significantly influenced AOB abundance only in August. Mowing significantly decreased AOA abundance and had little effect on AOA community compositions in May, while significantly influencing AOB abundance in both May and August, Moreover, AOA and AOB community structures showed obvious seasonal variations between May and August. Phylogenetic analysis showed that all AOA sequences fell into the Nitrososphaera cluster, and the AOB community was dominated by Nitrosospira Cluster 3. The results suggest that fertilization and mowing play important roles in affecting the abundance and community compositions of AOA and AOB.
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Water addition regulates the metabolic activity of ammonia oxidizers responding to environmental perturbations in dry subhumid ecosystems.
Environ. Microbiol.
PUBLISHED: 01-12-2014
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Terrestrial arid and semi-arid ecosystems (drylands) constitute about 41% of the Earth's land surface and are predicted to experience increasing fluctuations in water and nitrogen availability. Mounting evidence has confirmed the significant importance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in nitrification, plant nitrogen availability and atmospheric N2 O emissions, but their responses to environmental perturbations in drylands remain largely unknown. Here we evaluate how the factorial combinations of irrigation and fertilization in forests and land-use change from grassland to forest affects the dynamics of AOA and AOB following a 6-year dryland field study. Potential nitrification rates and AOA and AOB abundances were significantly higher in the irrigated plots, accompanied by considerable changes in community compositions, but their responses to fertilization alone were not significant. DNA-stable isotope probing results showed increased (13) CO2 incorporation into the amoA gene of AOA, but not of AOB, in plots receiving water addition, coupled with significantly higher net mineralization and nitrification rates. High-throughput microarray analysis revealed that active AOA assemblages belonging to Nitrosopumilus and Nitrosotalea were increasingly labelled by (13) CO2 following irrigation. However, no obvious effects of land-use changes on nitrification rates or metabolic activity of AOA and AOB could be observed under dry conditions. We provide evidence that water addition had more important roles than nitrogen fertilization in influencing the autotrophic nitrification in dryland ecosystems, and AOA are increasingly involved in ammonia oxidation when dry soils become wetted.
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Extravascular lung water and pulmonary arterial wedge pressure for fluid management in patients with acute respiratory distress syndrome.
Multidiscip Respir Med
PUBLISHED: 01-07-2014
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Extravascular lung water (EVLW) is a sensitive prognostic indicator of pulmonary edema. Thus, EVLW may be an advantageous method of fluid management. This study aims to evaluate the outcomes of using EVLW and pulmonary artery wedge pressure (PAWP) as strategies for fluid management in patients with acute respiratory distress syndrome (ARDS).
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Wheatstone bridge giant-magnetoresistance based cell counter.
Biosens Bioelectron
PUBLISHED: 01-06-2014
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A Wheatstone bridge giant magnetoresistance (GMR) biosensor was proposed here for the detection and counting of magnetic cells. The biosensor was made of a top-pinned spin-valve layer structure, and it was integrated with a microchannel possessing the function of hydrodynamic focusing that allowed the cells to flow in series one by one and ensured the accuracy of detection. Through measuring the magnetoresistance variation caused by the stray field of the magnetic cells that flowed through the microchannel above the GMR biosensor, we can not only detect and count the cells but we can also recognize cells with different magnetic moments. In addition, a magnetic field gradient was applied for the separation of different cells into different channels.
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Compare analysis for the nanotoxicity effects of different amounts of endocytic iron oxide nanoparticles at single cell level.
PLoS ONE
PUBLISHED: 01-01-2014
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Developing methods that evaluate the cellular uptake of magnetic nanoparticles (MNPs) and nanotoxicity effects at single-cellular level are needed. In this study, magnetophoresis combining fluorescence based cytotoxicity assay was proposed to assess the viability and the single-cellular MNPs uptake simultaneously. Malignant cells (SKHep-1, HepG2, HeLa) were incubated with 10 nm anionic iron oxide nanoparticles. Prussian blue stain was performed to visualize the distribution of magnetic nanoparticles. MTT and fluorescence based assay analyzed the cytotoxicity effects of the bulk cell population and single cell, respectively. DAPI/PI stained was applied to evaluate death mechanism. The number of intracellular MNPs was found to be strongly correlated with the cell death. Significant differences between cellular MNP uptake in living and dead cells were observed. The method could be useful for future study of the nanotoxicity induced by MNPs.
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Effects of daidzein and kiwifruit on bone mineral density and equol production in ovariectomised rats.
Int J Food Sci Nutr
PUBLISHED: 11-19-2013
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Abstract In this study, we investigated the synergistic effects of daidzein (Dz) and kiwifruit on bone and equol production in ovariectomised (OVX) rats. Female Sprague-Dawley rats were randomly assigned to one of five groups: sham operated, OVX control, OVX fed 0.1% Dz-supplemented diet (OVX?+?Dz), OVX fed 0.1% Dz and green kiwifruit (GRK)-supplemented diet (OVX?+?Dz?+?GRK) and OVX fed 0.1% Dz and gold kiwifruit (GOK)-supplemented diet (OVX?+?Dz?+?GOK). There were no significant differences in whole body and femur bone mineral density (BMD) among groups at week 8. BMD in the OVX group significantly decreased at week 8; however, BMD in the OVX?+?Dz?+?GRK was not significantly different from baseline in the end of the study. However, supplementation with kiwifruit did not affect urinary equol concentrations, urinary ratios of equol to Dz and the composition of caecal microbiota. These results suggest that the combination of Dz and GRK may slightly reduce bone loss caused by oestrogen deficiency but does not affect equol production.
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[Olfactory function in patients with idiopathic rapid eye movement sleep behavior disorder].
Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi
PUBLISHED: 09-11-2013
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To analyze the correlation between olfactory bulb (OB) volume with depth of olfactory sulcus (OS) and olfactory function in patients with idiopathic rapid eye movement sleep behavior disorder (iRBD).
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PPh3 -Catalyzed Ring-Expansion Reactions of Sulfamate-Derived Cyclic Imines with Acetylenedicarboxylates.
Chem Asian J
PUBLISHED: 08-12-2013
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The PPh3 -catalyzed ring-expansion reaction of sulfamate-derived cyclic imines with acetylenedicarboxylates has been developed. The reaction works quite efficiently under very mild conditions to afford benzo[g][1,2,3]oxathiazocine-4,5-dicarboxylate 2,2-dioxide derivatives in high yields.
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[Olfactory bulb volume and depth of olfactory sulcus in patients with idiopathic olfactory loss].
Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi
PUBLISHED: 07-27-2013
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To analyze the correlation between olfactory bulb(OB) volume with depth of olfactory sulcus (OS) and olfactory function in patients with idiopathic olfactory loss (IOL).
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[Cytoplasmic expression of P27 protein and its correlation with clinicopathologic features of nasopharyngeal carcinoma].
Nan Fang Yi Ke Da Xue Xue Bao
PUBLISHED: 06-28-2013
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To evaluate the correlation of p27 protein expression in the cytoplasm with the clinicopathologic features of nasopharyngeal carcinoma (NPC).
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Evidence of circulation of an epidemic strain of Pasteurella multocida in Jiangsu, China by multi-locus sequence typing (MLST).
Infect. Genet. Evol.
PUBLISHED: 06-17-2013
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Pasteurella multocida, the causative agent of fowl cholera, is a serious threat to poultry farming. In this study, we isolated and identified 40 P. multocida strains in fowl cholera outbreaks in Jiangsu province, China. The identified P. multocida was further characterized using multi-locus sequence typing (MLST). All of the 40 P. multocida strains studied are genetically identical and belong to the ST129 sequence type based on seven MLST loci. Our study provides evidence of a circulating epidemic strain of P. multocida in Jiangsu, China.
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[Transsphenoidal endoscopic endonasal approach for the resection of Rathke cleft cysts].
Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi
PUBLISHED: 06-13-2013
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To evaluate the effectiveness of transsphenoidal endoscopic endonasal approach for the resection of Rathke cleft cysts (RCC).
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Single cell detection using a magnetic zigzag nanowire biosensor.
Lab Chip
PUBLISHED: 06-12-2013
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A magnetic zigzag nanowire device was designed for single cell biosensing. Nanowires with widths of 150, 300, 500, and 800 nm were fabricated on silicon trenches by electron beam lithography, electron beam evaporation, and lift-off processes. Magnetoresistance measurements were performed before and after the attachment of a single magnetic cell to the nanowires to characterize the magnetic signal change due to the influence of the magnetic cell. Magnetoresistance responses were measured in different magnetic field directions, and the results showed that this nanowire device can be used for multi-directional detection. It was observed that the highest switching field variation occurred in a 150 nm wide nanowire when the field was perpendicular to the substrate plane. On the other hand, the highest magnetoresistance ratio variation occurred in a 800 nm wide nanowire also when the field was perpendicular to the substrate plane. Besides, the trench-structured substrate proposed in this study can fix the magnetic cell to the sensor in a fluid environment, and the stray field generated by the corners of the magnetic zigzag nanowires has the function of actively attracting the magnetic cells for detection.
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[A case of diffuse large B-cell lymphoma in ethmoid sinus].
Lin Chung Er Bi Yan Hou Tou Jing Wai Ke Za Zhi
PUBLISHED: 06-05-2013
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The typical clinical manifestations of diffuse large B-cell lymphoma (DLBCL) included nasal obstruction, rhinorrhea, bleeding in nose, headache,etc. No typical features were seen in CT and MRI. The diagnosis of DLBCL was based on the criteria established by the WHO classification. Morphological and immunohistochemical examination were necessary in the diagnosis of DLBCL.
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[Research on the application of grey system theory in the pattern recognition for chromatographic fingerprints of traditional Chinese medicine].
Se Pu
PUBLISHED: 05-24-2013
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A model based on grey system theory was proposed for pattern recognition in chromatographic fingerprints (CF) of traditional Chinese medicine (TCM). The grey relational grade among the data series of each testing CF and the ideal CF was obtained by entropy and norm respectively, then the principle of "maximal matching degree" was introduced to make judgments, so as to achieve the purpose of variety identification and quality evaluation. A satisfactory result in the high performance liquid chromatographic (HPLC) analysis of 56 batches of different varieties of Exocarpium Citrus Grandis was achieved with this model. The errors in the chromatographic fingerprint analysis caused by traditional similarity method or grey correlation method were overcome, as the samples of Citrus grandis Tomentosa and Citrus grandis (L.) Osbeck were correctly distinguished in the experiment. Furthermore in the study on the variety identification of Citrus grandis Tomentosa, the recognition rates were up to 92.85%, although the types and the contents of the chemical compositions of the samples were very close. At the same time, the model had the merits of low computation complexity and easy operation by computer programming. The research indicated that the grey system theory has good applicability to pattern recognition in the chromatographic fingerprints of TCM.
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Minimizing matrix effect by femtosecond laser ablation and ionization in elemental determination.
Anal. Chem.
PUBLISHED: 04-22-2013
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Matrix effect is unavoidable in direct solid analysis, which usually is a leading cause of the nonstoichiometric effect in quantitative analysis. In this research, experiments were carried out to study the overall characteristics of atomization and ionization in laser-solid interaction. Both nanosecond (ns) and femtosecond (fs) lasers were applied in a buffer-gas-assisted ionization source coupled with an orthogonal time-of-flight mass spectrometer. Twenty-nine solid standards of ten different matrices, including six metals and four dielectrics, were analyzed. The results indicate that the fs-laser mode offers more stable relative sensitivity coefficients (RSCs) with irradiance higher than 7 × 10(13) W·cm(-2), which could be more reliable in the determination of element composition of solids. The matrix effect is reduced by half when the fs-laser is employed, owing to the fact that the fs-laser ablation and ionization (fs-LAI) incurs an almost heat-free ablation process and creates a dense plasma for the stable ionization.
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Single-cell elemental analysis via high irradiance femtosecond laser ionization time-of-flight mass spectrometry.
Anal. Chem.
PUBLISHED: 04-18-2013
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In modern bioanalytics, elemental analysis of single cells is important yet challenging due to the complicated biological matrices and elemental contents. We have developed the high irradiance femtosecond laser ionization orthogonal time-of-flight mass spectrometry (fs-LI-O-TOFMS) to determine the elemental composition of individual cells. The sample preparation procedure is simple and fast through heating and drying the cells. Under typical operating conditions, elements above femtogram levels in a single cell can be clearly observed in the spectrum with reasonable isotope ratios. Some of the nonmetallic elements that are difficult to measure by ICPMS, such as P, S, and Cl, can be easily determined by fs-LI-O-TOFMS. Replicate analyses show that signal variations are 15-35% for metallic elements and 25-50% for nonmetallic elements. The results demonstrate that fs-LI-O-TOFMS is a simple, rapid, and practical tool for the elemental determination of single cells.
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Role of three-body recombination for charge reduction in MALDI process.
Analyst
PUBLISHED: 03-30-2013
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Ions in Matrix-Assisted Laser Desorption/Ionization (MALDI) are predominantly singly charged for small analyte molecules. With the estimated high number density and low temperature of electrons, the three-body recombination mechanism is attractive and should be considered as an important cause for the charge reduction in the plume. Theoretical calculations indicate that the rate coefficient of the three-body recombination is about 50 times higher than that of the two-body recombination if the analyte molecule has insufficient degrees of freedom. Experimental results show that, for small analyte molecules, the ratio of AH2(2+)/AH(+) is close to the theoretical 5% value from the three-body recombination modeling and this ratio declines with the increasing electron and matrix molecule number density caused by greater laser irradiance. The ratio of [A + 2](+)/[A + 1](+) is higher than the theoretical isotopic value, and the excess [A + 2](+) could exclusively result from the three-body recombination collisions. Further evidence demonstrates that [A + 2](+)/[A + 1](+) increases with electron number density, which is in correspondence with the model. All of these theoretical and experimental results indicate that three-body recombination is an essential charge reduction mechanism for small molecules in the MALDI plume.
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Influence of electrolytes on contact angles of droplets under electric field.
Analyst
PUBLISHED: 03-06-2013
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The change of contact angle is one of the major subjects in the studies of electrowetting on dielectrics. A larger change in contact angle with a less applied electric potential has been pursued by the researchers on digital microfluidics. From previous research it is concluded that the effect of free charges in electrolytes on contact angles can almost be neglected. In this article, obvious influences of free charges on contact angles are presented and discussed. To verify the influence of free charges, both weak electrolyte (boric acid) and strong electrolyte (sodium chloride) are used as sources of free charges in our experiment. It was found that the increase of ion concentration enhances the contact angle variation due to the attraction between the bound surface charges in the dielectric layer and the free counter-ions in the solution. The saturated contact angle occurs with a lower electric potential compared with de-ionized water due to the shielding of the electric field by the free counter-ions. When a strong electrolyte is used, the contact angle varies at a much higher rate than with de-ionized water, and the huge amount of accumulated free ions shields the driving field, causing the contact angle to saturate at a much lower electric potential. The saturated contact angle in strong electrolyte solution is markedly larger than those in weak electrolyte solutions and de-ionized water.
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Differential response of archaeal groups to land use change in an acidic red soil.
Sci. Total Environ.
PUBLISHED: 01-30-2013
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Land use management, one of the most important aspects of anthropogenic disturbance to terrestrial ecosystems, has exerted overriding impacts on soil biogeochemical cycling and inhabitant microorganisms. However, the knowledge concerning response of different archaeal groups to long-term land use changes is still limited in terrestrial environments. Here we used quantitative polymerase chain reaction (qPCR) and denaturing gradient gel electrophoresis (DGGE) approaches to investigate the response of archaeal communities to four different land use practices, i.e. cropland, pine forest, restoration land and degradation land. qPCR analyses showed that expression of the archaeal amoA gene responds more sensitively to changes of land use. In particular, we observed, occurring at significantly lower numbers of archaeal amoA genes in degradation land samples, while the abundance of total archaea and Group 1.1c based on 16S rRNA gene copy numbers remained constant among the different treatments examined. Soil nitrate content is significantly correlated with archaeal amoA gene abundance, but not their bacterial counterparts. The percentage of archaea among total prokaryote communities increases with increasing depth, but has no significant relationship with total carbon, total nitrogen or pH. Soil pH was significantly correlated with total bacterial abundance. Based on results from PCR-DGGE, three land use practices (i.e. cropland, pine forest, restoration land) showed distinct dominant bands, which were mostly affiliated with Group 1.1a. Degradation land, however, was dominated by sequences belonging to Group 1.1c. Results from this study suggest that community structure of ammonia oxidizing archaea were significantly impacted by land use practices.
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A model to discriminate malignant from benign thyroid nodules using artificial neural network.
PLoS ONE
PUBLISHED: 01-01-2013
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This study aimed to construct a model for using in differentiating benign and malignant nodules with the artificial neural network and to increase the objective diagnostic accuracy of US.
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Ammonia-oxidizing archaea have more important role than ammonia-oxidizing bacteria in ammonia oxidation of strongly acidic soils.
ISME J
PUBLISHED: 12-01-2011
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Increasing evidence demonstrated the involvement of ammonia-oxidizing archaea (AOA) in the global nitrogen cycle, but the relative contributions of AOA and ammonia-oxidizing bacteria (AOB) to ammonia oxidation are still in debate. Previous studies suggest that AOA would be more adapted to ammonia-limited oligotrophic conditions, which seems to be favored by protonation of ammonia, turning into ammonium in low-pH environments. Here, we investigated the autotrophic nitrification activity of AOA and AOB in five strongly acidic soils (pH<4.50) during microcosm incubation for 30 days. Significantly positive correlations between nitrate concentration and amoA gene abundance of AOA, but not of AOB, were observed during the active nitrification. (13)CO(2)-DNA-stable isotope probing results showed significant assimilation of (13)C-labeled carbon source into the amoA gene of AOA, but not of AOB, in one of the selected soil samples. High levels of thaumarchaeal amoA gene abundance were observed during the active nitrification, coupled with increasing intensity of two denaturing gradient gel electrophoresis bands for specific thaumarchaeal community. Addition of the nitrification inhibitor dicyandiamide (DCD) completely inhibited the nitrification activity and CO(2) fixation by AOA, accompanied by decreasing thaumarchaeal amoA gene abundance. Bacterial amoA gene abundance decreased in all microcosms irrespective of DCD addition, and mostly showed no correlation with nitrate concentrations. Phylogenetic analysis of thaumarchaeal amoA gene and 16S rRNA gene revealed active (13)CO(2)-labeled AOA belonged to groups 1.1a-associated and 1.1b. Taken together, these results provided strong evidence that AOA have a more important role than AOB in autotrophic ammonia oxidation in strongly acidic soils.
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[The study on high-resolution HLA and human cytomegalovirus (HCMV) viremia in bone marrow transplantation recipients].
Zhonghua Shi Yan He Lin Chuang Bing Du Xue Za Zhi
PUBLISHED: 11-01-2011
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To study the correlation between high-resolution HLA-A * 1101, HLA-A * 0201, HLA-A * 2402, HLA-B * 4001, HLA-DRB1 * 0901 with HCMV pp65 antigenemia after bone marrow transplantation (BMT) in China.
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Depression, anxiety and influencing factors in patients with acute pulmonary embolism.
Chin. Med. J.
PUBLISHED: 09-22-2011
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Psychological distress has been widely studied in many cardiovascular and pulmonary diseases, but the condition in acute pulmonary embolism (APE) is unknown. The purpose of this study was to investigate levels of depression and anxiety and their influencing factors in APE patients.
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Bladder cancer determination via two urinary metabolites: a biomarker pattern approach.
Mol. Cell Proteomics
PUBLISHED: 07-28-2011
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The purpose of this study was to use metabonomic profiling to identify a potential specific biomarker pattern in urine as a noninvasive bladder cancer (BC) detection strategy. A liquid chromatography-mass spectrometry based method, which utilized both reversed phase liquid chromatography and hydrophilic interaction chromatography separations, was performed, followed by multivariate data analysis to discriminate the global urine profiles of 27 BC patients and 32 healthy controls. Data from both columns were combined, and this combination proved to be effective and reliable for partial least squares-discriminant analysis. Following a critical selection criterion, several metabolites showing significant differences in expression levels were detected. Receiver operating characteristic analysis was used for the evaluation of potential biomarkers. Carnitine C9:1 and component I, were combined as a biomarker pattern, with a sensitivity and specificity up to 92.6% and 96.9%, respectively, for all patients and 90.5% and 96.9%, respectively for low-grade BC patients. Metabolic pathways of component I and carnitine C9:1 are discussed. These results indicate that metabonomics is a practicable tool for BC diagnosis given its high efficacy and economization. The combined biomarker pattern showed better performance than single metabolite in discriminating bladder cancer patients, especially low-grade BC patients, from healthy controls.
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[Production of porcine blastocysts expressed EGFP by handmade cloning].
Yi Chuan
PUBLISHED: 05-19-2011
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Production of transgenic animals via somatic cell nuclear transfer (SCNT) has been widely used worldwide. However, the application of SCNT is impeded by overall high costs and low efficiency. Here, we reported a modification of the existing technology in order to overcome some of the disadvantages associated with SCNT. Firstly, a marker gene, enhanced green fluorescent gene (EGFP), was transfected into pig fetal fibroblast cells, and was subsequently screened by fluorescent expression to ensure donor cells expressing EGFP. Porcine embryos expressing EGFP were then produced by a method called handmade cloning (HMC), a simplified method for micromanipulation. To demonstrate the concept, we collected a total of 378 fresh swine oocytes, from which 266 with the nucleus removed, obtained a total of 127 viable recombinant oocytes after fusion with EGFP-expressing cells. In vitro incubation of the 127 recombinant oocytes for approximately 144 hours resulted in successful generation of 65 viable embryos, with an average success rate of 52.1±8.3%. Compared with the traditional SCNT, the method of HMC is not only easy to operate, but also increases the rate of recombinant embryo significantly. Furthermore, the modified method no longer relies on expensive instrument like micromanipulator, facilitating the industrialization of transgenic animal production.
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Progress in structure-based drug design against influenza A virus.
Expert Opin Drug Discov
PUBLISHED: 03-26-2011
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Introduction: The 2009-H1N1 influenza pandemic has prompted new global efforts to develop new drugs and drug design techniques to combat influenza viruses. While there have been a number of attempts to provide drugs to treat influenza, drug resistance has been a major problem with only four drugs currently approved by the FDA for its treatment. Areas covered: In this review, the drug-resistant problem of influenza A viruses is discussed and summarized. The article also introduces the experimental and computational structures of drug targeting proteins, neuraminidases, and of the M2 proton channel. Furthermore, the article illustrates the latest drug candidates and techniques of computer-aided drug design with examples of their application, including virtual in silico screening and scoring, AutoDock and evolutionary technique AutoGrow. Expert opinion: Structure-based drug design is the inventive process for finding new drugs based on the structural knowledge of the biological target. Computer-aided drug design strategies and techniques will make drug discovery more effective and economical. It is anticipated that the recent advances in structure-based drug design techniques will greatly help scientists to develop more powerful and specific drugs to fight the next generation of influenza viruses.
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Simultaneous acquisition of elemental, fragmental, and molecular information on organometallic compounds.
Anal. Chem.
PUBLISHED: 02-23-2011
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A novel method for obtaining elemental, fragmental, and molecular information of organometallic compounds has been developed using high irradiance laser induced time-of-flight mass spectrometry (LI-TOFMS) with a buffer-gas-assisted ion source. This technique permits direct and matrix-free analysis of solid analyte with minimal sample preparation. In addition, it shows special advantages in integrated acquisition of elemental, fragmental, and molecular information from a single target, on the basis of which identification of organometallic complexes is simplified and expedited.
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LC-MS based serum metabonomic analysis for renal cell carcinoma diagnosis, staging, and biomarker discovery.
J. Proteome Res.
PUBLISHED: 02-04-2011
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A LC-MS based method, which utilizes both reversed-performance (RP) chromatography and hydrophilic interaction chromatography (HILIC) separations, has been carried out in conjunction with multivariate data analysis to discriminate the global serum profiles of renal cell carcinoma (RCC) patients and healthy controls. The HILIC was found necessary for a comprehensive serum metabonomic profiling as well as RP separation. The feasibility of using serum metabonomics for the diagnosis and staging of RCC has been evaluated. One-hundred percent sensitivity in detection has been achieved, and a satisfactory clustering between the early stage and advanced-stage patients is observed. The results suggest that the combination of LC-MS analysis with multivariate statistical analysis can be used for RCC diagnosis and has potential in the staging of RCC. The MS/MS experiments have been carried out to identify the biomarker patterns that made great contribution to the discrimination. As a result, 30 potential biomarkers for RCC are identified. It is possible that the current biomarker patterns are not unique to RCC but just the result of any malignancy disease. To further elucidate the pathophysiology of RCC, related metabolic pathways have been studied. RCC is found to be closely related to disturbed phospholipid catabolism, sphingolipid metabolism, phenylalanine metabolism, tryptophan metabolism, fatty acid beta-oxidation, cholesterol metabolism, and arachidonic acid metabolism.
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Sensitive and selective off-on rhodamine hydrazide fluorescent chemosensor for hypochlorous acid detection and bioimaging.
Talanta
PUBLISHED: 01-28-2011
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A rhodamine 6G hydrazide fluorescent chemosensor was prepared for the rapid HOCl detection in aqueous media. The system makes good use of the irreversible HOCl-mediated selective oxidation reaction to generate fluorescent response proportional to the amount of HOCl in neutral buffer. This probe exhibits great photostability, high sensitivity, and good selectivity for HOCl over other reactive species and most of the common metal ions. Furthermore, the probe is cell membrane permeable, and its applicability has been successfully demonstrated for fluorescence imaging of both exogenous and endogenous HOCl within living cells. Cytotoxicity assays prove that this probe is almost nontoxic to the cultured cell lines under the experimental conditions.
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Loneliness among the rural older people in Anhui, China: prevalence and associated factors.
Int J Geriatr Psychiatry
PUBLISHED: 01-27-2011
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To clarify the prevalence of loneliness and evaluate the impact of social support, family function and socio-demographic factors on loneliness and their correlation among the rural older people in Anhui, China.
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Analysis of beryllium to biomolecule binding using a metal specific fluorescent probe and competitive assay.
Talanta
PUBLISHED: 01-24-2011
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Studying metal-biomolecule interactions is critical to the elucidation of the molecular basis of the biological functions and toxicity of metals. In the present study, a competitive fluorimetric approach has been developed to measure the apparent affinity of biomolecules for Be(2+) by using a Be(2+)-specific fluorigenic probe (10-hydroxybenzo[h]quinoline-7-sulfonate, HBQS). Under physiological conditions, HBQS coordinates with Be(2+) in a molar ratio of 1:1 and results in a fluorescence shift from 580 nm for HBQS to 480 nm for the Be-HBQS complex associated with significant fluorescence enhancement. When a beryllium ligand is present in the mixture of Be(2+) and HBQS, the competition of ligand against HBQS for beryllium ion binding results in dissociation and thus a fluorescence decrease of the Be-HBQS complex. By titrating ligand and monitoring the dose-dependent decrease of Be-HBQS complex fluorescence at 480 nm, the apparent affinity between ligand and Be(2+) can be derived. Applying this simple approach, the apparent affinities of various nucleotides and the iron-storage protein ferritin for beryllium ion have been determined. In particular, the apparent dissociation constant of Be(2+) and adenosine 5-triphosphate (ATP) was also validated by an electrospray ionization mass spectrometric (ESI-MS) method. The general applicability of the proposed competition assay was further demonstrated using FluoZin-1, a zinc fluorescent indicator, in a binding study for Zn(2+) and bovine serum albumin. This newly developed competitive fluorimetric assay provides a sensitive, simple, and generic approach for affinity estimation of metal and biomolecule binding.
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Synthesis of metal ion-histidine complex functionalized mesoporous silica nanocatalysts for enhanced light-free tooth bleaching.
Acta Biomater
PUBLISHED: 01-07-2011
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Several metal ion-histidine complex functionalized mesoporous silica nanoparticles (MSN) were synthesized and utilized as efficient catalysts for enhanced and light-free tooth bleaching. Fe(II), Mn(II), and Cu(II) ions were successfully immobilized in histidine-functionalized MSN and their catalytic abilities against discoloration of a dye (Orange II) in both test tubes and extracted tooth models were compared and discussed. Through direct observation of test tubes and calculation of mean color changes of extracted teeth we concluded that Fe(II)-his-MSN exhibited better catalytic competence than Mn(II)-his-MSN and Cu(II)-his-MSN because of its intrinsic redox ability. In test tubes Orange II was completely degraded within 6 h when Fe(II)-his-MSN was used as the catalyst. For the extracted tooth model the presence of Fe(II)- or Mn(II)-his-MSN significantly enhanced the efficacy of tooth bleaching for three regions, the enamel, outer dentin, and inner dentin, of stained teeth compared with H(2)O(2) alone. Furthermore, unlike current tooth bleaching techniques that need an LED or laser to catalyze H(2)O(2) bleaching, we demonstrated a light-free tooth bleaching system using Fe(II)-his-MSN as an efficient and reliable catalyst.
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Elemental imaging via laser ionization orthogonal time-of-flight mass spectrometry.
Anal. Chem.
PUBLISHED: 01-07-2011
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An elemental imaging method using a laser ionization orthogonal time-of-flight mass spectrometer system was developed for the simultaneous detection of all metal and nonmetal elements. The instrument control and data processing were realized by self-developed programs. This system is capable of simultaneous detection of metal and nonmetal elements, with a spatial resolution of 50 ?m, the lowest detection limits of 3 × 10(-7) g/g (Li), and a dynamic range of 7 orders of magnitude. Moreover, this technique does not require standards for quantitative analysis and can be a powerful and versatile tool for elemental imaging.
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High irradiance laser ionization orthogonal time-of-flight mass spectrometry: a versatile tool for solid analysis.
Mass Spectrom Rev
PUBLISHED: 01-03-2011
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This article reviews the development of and applications for high irradiance laser ionization orthogonal time-of-flight mass spectrometry (LI-O-TOFMS). LI-O-TOFMS has solved the bottleneck problems in traditional high irradiance laser ionization mass spectrometry, which allows the instrument to acquire explicit spectra with high resolution. A buffer-gas-assisted ion source effectively reduces the kinetic energy of the ions and suppresses the multiply charged ion interference. The pulse train data acquisition technique was applied to reduce the spectrum interference from multiply charged ions and polyatomic ions according to the temporal profiles of different ion packets in the repelling region. Relatively high laser irradiance (?10(10) W/cm(2)) is preferable for achieving uniform relative sensitivities for different elements in the samples of different matrices. LI-O-TOFMS has been used in the standardless, semiquantitative analysis of solids, which is proved to be a fast and convenient technique for solid sample analysis. By increasing the laser irradiance and reducing the buffer gas pressure, the determination of nonmetallic elements in solids can also be achieved without losing spectral explicity. Recent applications, such as elemental analysis of a single egg cell and acquiring elemental, fragmental, and molecular information of chemicals, were given to demonstrate the potential of the new technique. All of these results reveal that LI-O-TOFMS is an advanced tool in the elemental analysis of solids in terms of modern mass spectrometry.
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[Application of Lund concept in treating brain edema after severe head injury].
Zhongguo Wei Zhong Bing Ji Jiu Yi Xue
PUBLISHED: 10-28-2010
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To explore if the new treatment with Lund concept could reduce the mortality of patients after severe brain injury.
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Clinical significance of C-reactive protein values in antibiotic treatment for pyogenic liver abscess.
World J. Gastroenterol.
PUBLISHED: 10-13-2010
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To investigate the clinical significance of C-reactive protein (CRP) values in determining the endpoint of antibiotic treatment for liver abscess after drainage.
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Direct infusion mass spectrometry or liquid chromatography mass spectrometry for human metabonomics? A serum metabonomic study of kidney cancer.
Analyst
PUBLISHED: 09-21-2010
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Serum samples from kidney cancer patients and healthy controls were analyzed by both direct infusion mass spectrometry (DIMS) and liquid chromatography-mass spectrometry (LC-MS) with a high resolution ESI-Q-TOFMS. The classification and biomarker discovery capacities of the two methods were compared, and MS/MS experiments were carried out to identify potential biomarkers. DIMS had comparable classification and prediction capabilities to LC-MS but consumed only ~5% of the analysis time. With regard to biomarker discovery, twenty-three variables were found as potential biomarkers by DIMS, and 48 variables were obtained by LC-MS. DIMS is recommended to be a fast diagnostic method for kidney cancer, while LC-MS is necessary when comprehensive screening of biomarkers is required.
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Size differentiation and absolute quantification of gold nanoparticles via single particle detection with a laboratory-built high-sensitivity flow cytometer.
J. Am. Chem. Soc.
PUBLISHED: 08-17-2010
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Employing single nanoparticle detection with a laboratory-built high-sensitivity flow cytometer, we developed a simple and versatile platform that is capable of detecting the surface plasmon resonance scattering of gold nanoparticles (GNPs) as small as 24 nm, differentiating GNPs of different sizes, and providing accurate quantification of GNPs. Low-concentration samples (fM to pM) in small volumes (microL) can be measured in minutes with an analysis rate of up to 100-200 GNPs per second. Among these features, absolute quantification provides a distinct advantage because it does not require standard samples.
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[Larix gmelinii tree-ring width chronology and its responses to climate change in Kuduer, Great Xing an Mountains].
Ying Yong Sheng Tai Xue Bao
PUBLISHED: 05-26-2010
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Based on the established tree-ring width chronology of Larix gmelinii in Kuduer, Great Xing an Mountains, this paper analyzed the relationships between L. gmelinii tree-ring width chronology and related climatic variables, including air temperature, precipitation, and PDSI. In the study area, the L. gmelinii tree-ring width chronology was significantly negatively correlated with the air temperature in May and July (P<0.01), had no significant correlation with precipitation, but significantly positively correlated with the PDSI in June-August (P<0.05), suggesting that hydro-thermal variables had significant coupling effects to the radial growth of L. gmelinii in its growth season, particularly in May and July. The L. gmelinii tree-ring width chronology had significant correlations with large scale climatic regimes such as the Pacific Decadal Oscillation (PDO) in both low and high frequency variations, illustrating the significant effects of the remote oceanic climatic regimes to the local tree growth.
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[A preliminary study on screening for Porphyromonas gingivalis outer membrane protein antigen with two-dimensional liquid phase fractionation and matrix-assisted laser desorption ionization time-of-flight/time-of-flight mass spectrometry].
Zhonghua Kou Qiang Yi Xue Za Zhi
PUBLISHED: 05-09-2010
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To screen a variety of Porphyromonas gingivalis (Pg) common outer membrane proteins with two-dimensional liquid phase fractionation (PF2D) and matrix-assisted laser desorption ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF-MS) and provide candidate target antigen for the design of vaccines with cross protection against a variety of Pg.
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Impact of human leukocyte antigen matching on hepatitis B virus recurrence after liver transplantation.
HBPD INT
PUBLISHED: 04-13-2010
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Liver transplantation (LT) is an effective therapy for end-stage hepatitis B virus (HBV) infection. Recurrence of HBV is one of the frequent complications. In the present study, we investigated whether human leukocyte antigen (HLA) matching influences the incidence of HBV recurrence, and the time point of HBV recurrence after LT.
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Two-dimensional separation in laser ionization orthogonal time-of-flight mass spectrometry.
Anal. Chem.
PUBLISHED: 03-06-2010
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The capabilities of two-dimensional separation using a high irradiance laser ionization orthogonal time-of-flight mass spectrometer (LI-O-TOFMS) were demonstrated in this paper. Ions were separated via their initial kinetic energy in one dimension and their mass-to-charge ratios in the other dimension. Investigation of the transient ion profiles after laser pulses revealed that the separation of analyte ions from multiply charged ions and gas species ions was achieved. Comparison of mass spectra in the normal accumulation mode and in the two-dimensional separation mode indicated that the relative sensitivity coefficients are stable and close to their true values in the two-dimensional separation mode, especially for trace elements that are prone to interference.
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An extremely stable and sensitive end-column electrochemical detector based on heated copper microdisk electrode with direct current for CE and CE-Chip.
Analyst
PUBLISHED: 02-16-2010
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A heated copper microdisk electrode (HCME) was fabricated and successfully applied to capillary electrophoresis (CE) and CE-Chip as an electrochemical detector (ECD) for the detection of three carbohydrates and shikimic acid (SA) in Illicium verum Hook F., respectively. The temperature of HCME was heated by twin-wire-wound coil with direct current to reduce the magnetic interference. Coupled with CE and CE-chip, this detector exhibits both extremely stable and sensitive performance at elevated temperature compared with that at room temperature. In successive detection of three carbohydrates and shikimic acid (SA), the HCME exhibits very stable response with RSD of ca. 2% with elevated temperature without renewing the electrode, while at room temperature, RSD of ca. 20% is obtained. This is very important in practical applications that tedious works, such as polishing and re-fixing the electrode at each detection, can be therefore avoided. In addition, the sensitivity is about 2-6 time increased, and the linear range is about an order wider at elevated temperature (ca. 60 degrees C) than that at room temperature (ca. 25 degrees C).
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Laser ionization orthogonal time-of-flight mass spectrometry for simultaneous determination of nonmetallic elements in solids.
Anal. Chem.
PUBLISHED: 02-06-2010
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The simultaneous determination of nonmetallic elements in solid samples is difficult owing to their discrepant physical and chemical properties. We developed a high-irradiance laser ionization orthogonal time-of-flight mass spectrometry (LI-O-TOFMS) system and applied it for the determination of nonmetallic elements in solids. Helium was used as the buffer gas at 250 Pa in the source chamber; the laser irradiance was about 7 x 10(10) W/cm(2). A series of artificial standards containing B, C, N, O, F, Si, P, S, Cl, As, Br, Se, I, and Te were used. Explicit spectra were obtained with only a little interference from gas species and doubly charged matrix ions. Standardless semiquantitative analysis could be accomplished with a novel sampling methodology to obtain near-uniform sensitivity coefficients for different elements. Limits of detection (LOD) at microgram per gram level and a dynamic range of 6 orders of magnitude were achieved for most nonmetallic elements.
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High irradiance laser ionization mass spectrometry for direct speciation of iron oxides.
J. Am. Soc. Mass Spectrom.
PUBLISHED: 01-07-2010
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A novel method has been developed that allows the direct speciation analysis of iron oxides based on a modified laser ionization orthogonal time-of-flight mass spectrometer. Time resolved mass spectra were acquired for the investigation of elemental ions and oxide ions generated by a laser ionization source. Speciation methodologies, including the identification of characteristic ions and the use of ion abundance ratios were evaluated for the differentiation of the oxides. The influence of operating parameters on the distribution of cluster ions was investigated, and their mechanism of formation discussed.
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Beryllium uptake and related biological effects studied in THP-1 differentiated macrophages.
Metallomics
PUBLISHED: 09-14-2009
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Investigation of cellular uptake of metal compounds is important in understanding metal-related toxicity and diseases. Inhalation of beryllium aerosols can cause chronic beryllium disease, a progressive, granulomatous fibrosis of the lung. Studies in laboratory animals and cultured animal cells indicate that alveolar macrophages take up beryllium compounds and participate in a hypersensitivity immune response to a beryllium-containing antigen. In the present work, human monocyte cell line THP-1 was induced with phorbol myristate acetate to differentiate into a macrophage. This cell with characteristics of human alveolar macrophages was employed to study cellular beryllium uptake and related biological effects. Morphological changes, phagocytosis of fluorescent latex beads, and cell surface CD14 expression were used to verify the successful differentiation of THP-1 monocytes into macrophages. An improved mass spectrometry method for quantitative analysis of intracellular beryllium as opposed to the traditional radioisotopic approach was developed using ICP-MS. The influence of the solubility of beryllium compounds, exposure duration, and beryllium concentration on the incorporation of beryllium was studied. Our data indicated that the uptake of particulate BeO was much more significant than that of soluble BeSO(4), suggesting the major cellular uptake pathway is phagocytosis. Nevertheless, subsequent DAPI nuclear staining and PARP cleavage study indicated that beryllium uptake had a negligible effect on the apoptosis of THP-1 macrophages compared to the unstimulated macrophage control. Meanwhile, no substantial variation of tumour necrosis factor-alpha production was observed for THP-1 macrophages upon beryllium exposure. These data imply alveolar macrophages could have some level of tolerance to beryllium and this may explain why most Be-exposed individuals remain healthy throughout life.
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Femtogram detection and quantitation of residues using laser ionization orthogonal time-of-flight mass spectrometry.
Anal. Chem.
PUBLISHED: 09-12-2009
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A newly developed high irradiance laser ionization orthogonal time-of-flight mass spectrometer (LI-O-TOFMS) was employed for the elemental analysis of residues, which were prepared by evaporating mixed salt solutions. The residues were first characterized in terms of shape and elemental distribution. In TOFMS detection, all of the metal elements in the residue can be observed in the spectra. Relative sensitivity coefficients for different elements were within 1 order of magnitude, which meets semiquantitative analysis criteria. By calculating the individual masses from the ablated area due to a single laser shot, the absolute detection limit reached 7 x 10(-15) g for most metal elements. The results indicate that LI-O-TOFMS is capable of performing ultratrace elemental qualification and quantification, with an absolute limit of detection and an absolute limit of quantitation at the femtogram level.
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Investigation into adamantane-based M2 inhibitors with FB-QSAR.
Med Chem
PUBLISHED: 08-20-2009
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Because of their high resistance rate to the existing drugs, influenza A viruses have become a threat to human beings. It is known that the replication of influenza A viruses needs a pH-gated proton channel, the so-called M2 channel. Therefore, to develop effective drugs against influenza A, the most logic strategy is to inhibit the M2 channel. Recently, the atomic structure of the M2 channel was determined by NMR spectroscopy (Schnell, J.R. and Chou, J.J., Nature, 2008, 451, 591-595). The high-resolution NMR structure has provided a solid basis for structure-based drug design approaches. In this study, a benchmark dataset has been constructed that contains 34 newly-developed adamantane-based M2 inhibitors and covers considerable structural diversities and wide range of bioactivities. Based on these compounds, an in-depth analysis was performed with the newly developed fragment-based quantitative structure-activity relationship (FB-QSAR) algorithm. The results thus obtained provide useful insights for dealing with the drug-resistant problem and designing effective adamantane-based antiflu drugs.
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[Recombinant plasmid pEGFP-AFP-TK delivered by nano-magnetic fluids targeting killed AFP positive HepG2 cells in vitro].
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi
PUBLISHED: 05-12-2009
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To study recombinant plasmid pEGFP-AFP-TK delivered by nano-magnetic fluids targeting killed AFP positive HepG2 cells in vitro.
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Applicability of standardless semiquantitative analysis of solids by high-irradiance laser ionization orthogonal time-of-fight mass spectrometry.
Anal. Chem.
PUBLISHED: 05-05-2009
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A compact high-irradiance laser ionization time-of-flight mass spectrometry system has been developed for the multielemental analysis of solids. Helium was introduced into the ion source as a buffer gas to cool high kinetic energy ions and suppress the interference of multicharged ions. A special pulse train repelling mode was used to achieve explicit spectra. Two quantitative methods are described for the laser ionization mass spectrometry in this paper. The first of these is the routine calibration curve quantitation, in which various matrix-matched standards are required; the second method, which is based on the uniform correlation between the signal and elemental concentration of different samples, is more convenient and covers a typical dynamic range of 6 orders. All the investigations and results indicate satisfactory performance of the newly developed instrument and its applicability for simultaneous multielemental analysis of solid samples.
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Highly enhanced electrocatalytic oxidation of glucose and shikimic acid at a disposable electrically heated oxide covered copper electrode.
Chem. Commun. (Camb.)
PUBLISHED: 04-24-2009
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A heated oxide covered copper electrode (HOCE) was facilely fabricated for the first time, providing a highly enhanced electrocatalytic oxidation, and cost effective and sensitive determination for polyhydroxy compounds such as glucose and shikimic acid.
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Detection of human leukocyte antigen compatibility and antibodies in liver transplantation in China.
HBPD INT
PUBLISHED: 04-10-2009
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The exact roles of human leukocyte antigen (HLA) compatibility, HLA antibodies and underlying diseases in acute rejection of liver transplants are not clear. Moreover, cytomegalovirus (CMV) infection, one of the most common infections after transplantation, is related to HLA genotype and the incidence of acute rejection.
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Development of an ultrasensitive dual-channel flow cytometer for the individual analysis of nanosized particles and biomolecules.
Anal. Chem.
PUBLISHED: 03-06-2009
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A compact, high-sensitivity, dual-channel flow cytometer (HSDCFCM) was developed for the individual analysis of nanosized particles and biomolecules. A hydrodynamic focusing technique was applied to confine the sample stream and enable small probe volume. Fluorescence bursts from single R-phycoerythrin (R-PE) molecules passing through the laser beam were well resolved from the background with signal-to-noise ratio of 17. Excellent size discrimination was demonstrated with a mixture of three sizes of polystyrene nanoparticles. Simultaneous measurement of fluorescence and light scattering signals from individual nanoparticles was demonstrated with the 100 nm fluorescent latex beads. Doxorubicin-loaded ZrO(2) nanoparticles and fluorescently stained Escherichia coli ER2738 cells were analyzed successfully with dual-channel detection. Particle counting is demonstrated with the 210 nm fluorescent latex beads, and excellent correlation (R(2) > 0.998) between the manufacturer-reported concentrations and those measured by HSDCFCM enumeration was obtained. The measured sample detection efficiency was approximately 90% on average for particle concentrations ranging from 1.62 x 10(5) to 3.93 x 10(7) particles/mL. Sample mixtures with varying proportions of fluorescently labeled and unlabeled nanoparticles were also analyzed with good ratio correspondence. By providing rapid, quantitative, and multiparameter characterization of nanoparticles, it is believed that the HSDCFCM will find many applications in the fields of bionanotechnology, bioanalytical chemistry, and biomedicine.
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Physics and chemistry-driven artificial neural network for predicting bioactivity of peptides and proteins and their design.
J. Theor. Biol.
PUBLISHED: 03-06-2009
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Predicting the bioactivity of peptides and proteins is an important challenge in drug development and protein engineering. In this study we introduce a novel approach, the so-called "physics and chemistry-driven artificial neural network (Phys-Chem ANN)", to deal with such a problem. Unlike the existing ANN approaches, which were designed under the inspiration of biological neural system, the Phys-Chem ANN approach is based on the physical and chemical principles, as well as the structural features of proteins. In the Phys-Chem ANN model the "hidden layers" are no longer virtual "neurons", but real structural units of proteins and peptides. It is a hybridization approach, which combines the linear free energy concept of quantitative structure-activity relationship (QSAR) with the advanced mathematical technique of ANN. The Phys-Chem ANN approach has adopted an iterative and feedback procedure, incorporating both machine-learning and artificial intelligence capabilities. In addition to making more accurate predictions for the bioactivities of proteins and peptides than is possible with the traditional QSAR approach, the Phys-Chem ANN approach can also provide more insights about the relationship between bioactivities and the structures involved than the ANN approach does. As an example of the application of the Phys-Chem ANN approach, a predictive model for the conformational stability of human lysozyme is presented.
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