bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and Characterization of a New Quercetin‐bonded Stationary Phase for High Performance Liquid Chromatography
Authors: Li Laisheng , Fang Yishan , Chen Hong , Zhang Yang
Published: May 2012

A quercetin‐bonded silica gel stationary phase (QUSP) containing natural flavonoid ligand was first prepared viaγ‐glycidoxypropyltrimethoxysilane (KH‐560) as a coupling reagent for high‐performance liquid chromatography. Its chemical structure was characterized by Fourier infrared spectroscopy, elemental analysis, thermal thermogravimetry and13C cross polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR). The chromatographic property of QUSP was systematically evaluated by using neutral, basic and acidic aromatic compounds as probes. In order to clarify its retention mechanism, a comparative study of QUSP with conventional octadecylsilyl‐bonded stationary phase (ODS) was also carried out under the same conditions. The results showed that the new quercetin‐bonded phase exhibited an excellent reversed‐phase chromatographic property with relatively weak hydrophobicity. However, it has an advantage over ODS in the fast separation of polar aromatic compounds because the quercetin ligand could provide various sites besides hydrophobicity, such as hydrogen bonding, dipole‐dipole, π‐π staking and charge transfer interactions. QUSP was performed in the baseline separations of ionized polar basic or acidic compounds, including pyridines, anilines, pyrimidines, purines and phenols with symmetric peak shape in common mobile phases without buffer salt within relatively short time. The natural ligands from herbs are readily available and contain a variety of active sites, which facilitate the exploration of industrial chromatographic separation materials for green products.
Synthesis and Cyclization of 8‐Formyl‐2‐(phenoxymethyl)quinoline‐3‐carboxylic Acids
Authors: Gao Wentao , Zhao Zhigang , Li Yang , Yan Yan , Li Feng
Published: May 2012

A facile synthesis of a series of new quinoline‐8‐carbaldehyde compounds, namely 8‐formyl‐2‐(phenoxymethyl)quinoline‐3‐carboxylic acids (4a–4h) and 13‐oxo‐6,13‐dihydro[1]benzoxepino[3,4‐b]quinoline‐8‐carbaldehyde (5a–5g) is described, involving the one‐pot synthesis reaction of ethyl 2‐(chloromethyl)‐8‐formylquinoline‐3‐carboxylate (3) with substituted phenols followed by the intramolecular cyclization reaction via the treatment with polyphosphoric acid (PPA). Quinoline‐8‐carbaldehydes 4a–4h and 5a–5g are novel and their structures were supported by IR, 1H NMR, 13C NMR, MS and elemental analysis.
A Highly Sensitive Electrochemical Impedance Spectroscopy Immunosensor for Determination of 1‐Pyrenebutyric Acid Based on the Bifunctionality of Nafion/Gold Nanoparticles Composite Electrode
Authors: Yang Ping , Zheng Qiaoli , Xu He , Liu Jianshe , Jin Litong
Published: May 2012

A simple, highly sensitive and label‐free electrochemical impedance spectroscopy (EIS) immunosensor was developed using Nafion and gold nanoparticles (nano‐Au/Nafion) composites for the determination of 1‐pyrenebutyric acid (PBA). Under the optimal conditions, the amount of immobilized antibody was significantly improved on the nano‐Au/Nafion electrode due to the synergistic effect and biocompatibility of Nafion film and gold nanoparticles composites. The results showed that the sensitivity and stability of nano‐Au/Nafion composite electrode for PBA detection were much better than those of nano‐Au modified glassy carbon electrode (nano‐Au/GCE). The plot of increased electron transfer resistances (Rets) against the logarithm of PBA concentration is linear over the range from 0.1 to 150 ng·mL−1 with the detection limit of 0.03 ng·mL−1. The selectivity and accuracy of the proposed EIS immunosensor were evaluated with satisfactory results.
Facile Synthesis of Dendritic Hydroxyl‐terminated Cyanuric Chloride Derivatives and Their Properties
Authors: Lin Xiuxiu , Zhou Jianhua , Xu Dongmei
Published: May 2012

Novel dendritic compounds G1.5(OH)4 and G1.5(OH)8 with peripheral hydroxyl were synthesized under mild conditions from cyanuric chloride, ethylene diamine, ethanolamine and diethanolamine. The products could be separated and purified through dispersion and precipitation in organic solvents with good yields (over 93.0%) and high purity (above 98.0%, HPLC). The structures of the products were characterized by IR, MS, 1 H NMR and elementary analysis. G1.5(OH)4 and G1.5(OH)8 could be dissolved in polar solvents such as methanol, water and dimethylsulfoxide. TGA analysis showed that G1.5(OH)4 and G1.5(OH)8 had good thermo stability. The aqueous solutions of G1.5(OH)4 and G1.5(OH)8 exhibited low surface tension.
Facile Synthesis of 3‐Substituted Isoquinolines Derivatives via Microwave‐assisted Tandem Three‐component Coupling Cyclization
Authors: Lin Long , Wu Qiongyou , Huang Shaowei , Yang Guangfu
Published: May 2012

A novel three‐component reaction of o‐bromobenzaldehyde, terminal alkynes and tert‐butyl amine has been established, which proceeded smoothly to give 3‐substituted isoquinolines in good yields in the presence of palladium/copper catalysts under microwave irradiation.
A New Copper(I) Complex Based on Imidazole and Triphenylphosphine Ligands: Synthesis, Structure, Third‐Order NLO, and Fluorescence Properties
Authors: Liu Faqian , Jin Yanling , Liu Baocheng , Li Rongxun , Deng Yueyi , Li Weihua , Jian Fangfang
Published: May 2012

A new candidate [Cu(PPh3)2Him]Br (1, PPh3=triphenylphosphine, Him=1‐H‐imidazole) for nonlinear optical (NLO) materials has been synthesized and characterized crystallographically. The third‐order NLO optical properties were measured by the Z‐scan technique with an 8 ns pulsed laser at 532 nm. Compound 1 exhibits strong NLO absorptive abilities [α2=(61±5)×10−12] and effective self‐focusing performance [n2=(15±3)×10−18 m2·W−1] in 1.01×10−4 mol·dm−3 DMF solution. The compound also exhibits luminescence in DMF solution at room temperature and shows narrow emission with maximum at 382 nm. The electronic structure and photoluminescent process were investigated by means of TD‐DFT calculations. The results suggest that the contribution to the frontier orbitals from the CuBr δ bond plays a crucial role in its linear optical properties, and the origin of luminescence is attributable to the π∗︁→n transitions.
A Novel Method for Biomimetic Synthesis of Mannich Bases
Authors: Guo Yuan , An Jing , Lu Zhenhuan , Peng Mengjiao
Published: May 2012

Since the early studies of Mannich, Mannich reaction has become an important tool for the synthesis of new compounds. Mannich bases can be either directly employed or used as intermediates. In this work, the one‐carbon unit transfer reaction of tetrahydrofolate coenzyme was initiated. 1,3‐Dimethylimidazolidine as a new tetrahydrofolate coenzyme model at formaldehyde oxidation level was used to react with ketone having active hydrogen atoms and amine to give the corresponding Mannich base in good yield by a covert Mannich reaction. A novel method for biomimetic synthesis of various Mannich bases is provided.
Efficient Synthesis of the Functionalized Spiro[indoline‐3,4′‐pyridine] via Four‐component Reaction
Authors: Sun Jing , Wu Qun , Zhang Lijuan , Yan Chaoguo
Published: May 2012

An efficient synthetic procedure for the functionalized spiro[indoline‐3,4′‐pyridine] was developed via the four‐component reactions of arylamines, acetylenedicarboxylates, isatins and malononitrile with triethylamine as the base catalyst. The advantages of this reaction are using common starting material, mild reaction conditions, broad scope of reactants and operational simplicity.
Dimedone‐catalyzed Addition of Amines into Cyano Group: Facile Synthesis of Thiazol‐2‐yl Substituted E‐Acrylonitriles
Authors: Zhu Weijun , Tu Xingchao , Feng Hui , Tu Mansu , Jiang Bo , Wu Feiyue , Tu Shujiang
Published: May 2012

An efficient dimedone‐catalyzed synthesis of highly functionalized thiazol‐2‐yl substituted E‐acrylonitrile derivatives has been established through two‐step reaction of α‐thiocyanate ketones with malononitrile and amines. The α‐thiocyanate ketones were subjected with malononitrile to provide thiazol‐2‐ylidenemalononitrile derivatives, followed with various amines in the present of dimedone to yield the final thiazol‐2‐yl substituted acrylonitrile derivatives.
Synthesis and Insecticidal Activities of Novel Phthalic Acid Diamides
Authors: Yan Tao , Li Yuxin , Li Yongqiang , Wang Duoyi , Chen Wei , Liu Zhuo , Li Zhengming
Published: May 2012

In order to discover novel insecticides with the new action mode on ryanodine receptor (RyR), a series of novel phthalic acid diamide derivatives were designed and synthesized. All compounds were characterized by 1H NMR spectra and HRMS. The preliminary results of biological activity assessment indicated that some title compounds exhibited excellent insecticidal activities against Mythimna separata, Spodoptera exigua, and Plutella xylostella. The title compound 3‐nitro‐N‐cyclopropyl‐N′‐[2‐methyl‐4‐(perfluoropropan‐2‐yl)phenyl]phthalamide (4a) was more efficient against diamondback moths than the control (chlorantraniliprole). The effects of some title compounds on intracellular calcium of neurons from the Spodoptera exigua proved that the title compounds were RyR activators.
New Soluble Polyimides with High Optical Transparency and Light Color Containing Pendant Trifluoromethyl and Methyl Groups
Authors: Wang Chenyi , Zhao Xiaoyan , Li Guang
Published: May 2012

A new aromatic diamine containing trifluoromethyl and methyl groups, namely α,α‐bis(4‐amino‐3‐methylphenyl)‐4‐(trifluoromethyl)phenylmethane (1), was synthesized from 2‐methylaniline and 4‐(trifluoromethyl)benzaldehyde. A series of fluorinated polyimides (PIs) were prepared from the diamine with four commercially available aromatic tetracarboxylic dianhydrides using a one‐step high‐temperature polycondensation procedure. These obtained PIs showed excellent solubility, with the dissolvability at a concentration of 10 wt% in most solvents, and they could afford flexible and strong films. Thin films of these PIs exhibited high optical transparency and light color, with the cutoff wavelength at 324–357 nm and transmittance higher than 74% at 450 nm. Moreover, these PIs possessed eminent thermal stability and good mechanical properties.
Three‐Component Cucurbit[6]uril Framework with 1:2 Host‐Guest Motif and Dimeric Boric Acid
Authors: Wang Meng , Li Xiang , Liu Li
Published: May 2012

Three‐component framework of cucurbit[6]uril, 3‐(1‐methylimidazolium‐3‐yl)propane‐1‐sulfonate and boric acid has been constructed. The crystal structure reveals 1:2 host‐guest motif of cucurbit[6]uril and 3‐(1‐methyl‐imidazolium‐3‐yl)propane‐1‐sulfonate, demonstrating both cation binding of imidazolium moiety and anion binding of sulfonate moiety for the first time. Incorporation of dimeric boric acid facilitates the formation of metal‐free three‐dimensional framework.
Silicon‐Included Graphite Films Prepared by Thermally Induced CVD with a (C6F5)4Si Precursor
Authors: Bakovets Vladimir V. , Zelenina Ludmila N. , Levashova Tatiana M. , Uskov Evgeniy M.
Published: May 2012

Silicon‐included graphite films obtained by thermally induced (T)CVD from tetrakis(pentafluorephenyl)silane as a precursor are characterized by X‐ray diffraction (XRD), X‐ray microprobe analysis (XMA), X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Raman spectroscopy (RS). It is shown that Si‐included graphite films are produced in H2 or Ar flow at 500–600 °C. Air storage of the films causes a silicon oxidation, partly resulting in graphite with the inclusion of SiOx. Using the Van der Pauw method, the conductivity of the films is shown to be p‐type, the mobility of charge carriers is about 0.4 cm2 V−1 c−1, and their concentration is 1019 cm−3.
Utility‐optimal cross‐layer resource allocation in distributed wireless cooperative networks
Authors: Cui Haixia , Wei Gang , Zhang Han , Zhong Qinghua
Published: May 2012

In this paper, we propose a distributed cross‐layer resource allocation algorithm for wireless cooperative networks based on a network utility maximization framework. The algorithm provides solutions to relay selections, flow pass probabilities, transmit rate, and power levels jointly with optimal congestion control and power control through balancing link and physical layers such that the network‐wide utility is optimized. Via dual decomposition and subgradient method, we solve the utility‐optimal resource allocation problem by subproblems in different layers of the protocol stack. Furthermore, by introducing a concept of pseudochannel gain, we model both the primal direct logical link and its corresponding cooperative transmission link as a single virtual direct logical link to simplify our network utility framework. Eventually, the algorithm determines its primal resource allocation levels by employing reverse‐engineering of the pseudochannel gain model. Numerical experiments show that the convergence of the proposed algorithm can be obtained and the performance of the optimized network can be improved significantly. Copyright © 2012 John Wiley & Sons, Ltd.
Multi‐Layered hypertrophied MEE formation by microtubule disruption via GEF‐H1/RhoA/ROCK signaling pathway
Authors: Kitase Yukiko , Shuler Charles F.
Published: May 2012

Background: Formation of the secondary palate is complex and disturbance during palatal fusion may result in cleft palate. The processes of adhesion, intercalation, and disappearance of medial edge epithelia (MEE) are characterized by morphological changes requiring dynamic cytoskeletal rearrangement. Microtubules are one of the cytoskeletal elements involved in maintenance of cell morphology. Microtubule‐disrupting drugs have been reported to cause craniofacial malformations including cleft palate. The mechanisms underlying the failure of palatal fusion remain poorly understood. We evaluated the effect of nocodazole (NDZ), a drug that disrupts microtubules, on palatal fusion in organ culture. Results: NDZ caused failure of palatal fusion due to the induction of a multi‐layered hypertrophied MEE in the mid‐region of the secondary palatal shelves. Microtubule disruption increased RhoA activity and stress fiber formation. Pharmacological inhibition of the RhoA/ROCK pathway blocked multi‐layered MEE formation. Partial prevention of hypertrophied MEE was observed with Y27632 and cytochalasin, but not with blebbistatin. NDZ induced re‐localization of GEF‐H1 into cytoplasm from cell–cell junctions. Conclusions: The present study provided evidence that the GEF‐H1/RhoA/ROCK pathway plays a pivotal role in linking microtubule disassembly to the remodeling of the actin cytoskeleton, which resulted in a multi‐layered hypertrophied MEE and failure of palatal fusion. Developmental Dynamics 241:1169–1182, 2012. © 2012 Wiley Periodicals, Inc.
Characterization of small RNAs in X. tropicalis gastrulae
Authors: Faunes Fernando , Almonacid Leonardo I. , Melo Francisco , Larrain Juan
Published: May 2012

Here, we report and characterize deep sequencing data and bioinformatics analysis of small RNAs from X. tropicalis gastrula. A total of 17,553,124 reads with perfect match to the genome derived from 2,616,053 unique sequences were identified. Seventy‐seven percent of theses sequences were not found in previous reports from X. tropicalis oocytes and somatic tissues. Bioinformatics analyses indicate that a large fraction of the small RNAs are PIWI‐interacting RNAs. Up to 23.9% of small RNAs mapped to transposable elements and 27% to genic regions. Most of the abundant transposon‐derived small RNAs are found in oocyte and gastrula libraries, suggesting that transposons also need to be silenced during early embryonic development. Importantly, novel clusters of piRNAs whose expression is activated after zygotic transcription begins were identified in the genome of X. tropicalis. Additionally, miRNAs were also identified and many of them are not present in oocytes, suggesting that miRNA expression is stage‐specific. To the best of our knowledge, this is the first high throughput data release and bioinformatics characterization of small RNAs during Xenopus early embryonic development. genesis 50:572–58, 2012. © 2012 Wiley Periodicals, Inc.
Common use of anticholinergic medications in older patients with schizophrenia: findings of the Research on Asian Psychotropic Prescription Pattern (REAP) study, 2001–2009
Authors: Xiang Yu‐Tao , Dickerson Faith , Kreyenbuhl Julie , Ungvari Gabor S. , Wang Chuan‐Yue , Si Tian‐Mei , Lee Edwin H. M. , Chiu Helen F. K. , Lai Kelly Y. C. , He Yan‐Ling , Yang Shu‐Yu , Chong Mian‐Yoon , Tan Chay‐Hoon , Kua Ee‐Heok , Fujii Senta , Sim Kang , Yong Michael K. H. , Trivedi Jitendra K. , Chung Eun‐Kee , Udomratn Pichet , Chee Kok‐Yoon , Sartorius Norman , Shinfuku Naotaka
Published: May 2012

Objective

This study surveyed the use of anticholinergic medications (ACMs) in older Asian patients with schizophrenia and examined its demographic and clinical correlates.

Method

A total of 1452 hospitalized patients with schizophrenia aged 55 years or older in nine Asian countries and territories were surveyed between 2001 and 2009. The cross‐sectional data of patients' socio‐demographic and clinical characteristics and the prescriptions of antipsychotic drugs and ACM were recorded using a standardized protocol and data collection procedure.

Results

The frequency of ACM prescription was 64.6% in the pooled sample, with 72.4%, 61.9%, and 59.5% in 2001, 2004, and 2009, respectively. Multiple logistic regression analysis of the whole sample revealed that patients on ACM had a higher dose of antipsychotic medications, and were more likely to have extrapyramidal side effects and receive first‐generation antipsychotic medications.

Conclusions

Anticholinergic medications were frequently used in older Asian patients with schizophrenia. Considering the potential side effects of ACM, the rationale for their widespread use in this patient population should be revisited. Copyright © 2012 John Wiley & Sons, Ltd.
A Return on Investment Assessment Model for a Mobile User Interface Project at the Predevelopment Stage
Authors: Kim Min‐Jeong , Park Jonghun
Published: May 2012

We present a new approach for assessing the business performance of a mobile user interface (UI) project at its predevelopment stage. Traditionally, the performance measurement of a mobile UI is made from the perspective of usability. Yet, as the number of mobile phone users is rapidly increasing, and, given that stakeholders are beginning to realize the importance of the UI, there is a growing demand to measure its business performance quantitatively as well as qualitatively. This article presents a model that can facilitate Return on Investment (ROI) estimations pertaining to the development of a mobile UI before the service with the new UI is launched. We base our method on stated preference data for the purpose of applying a conjoint analysis. Subsequently, we evaluate the viability of the proposed model quantitatively by comparing the estimated ROI at the predevelopment stage with the actual sales revenue achieved after the launch of the service. The proposed model was successfully applied to real‐world mobile UI design projects at Korea Telecom. Its benefits are demonstrated here through a case study. © 2012 Wiley Periodicals, Inc.
The influence of salinity on hysteresis of soil water‐retention curves
Authors: Ma Kuo‐Chen , Lin Yong‐Jun , Tan Yih‐Chi
Published: May 2012

Taiwan is surrounded by the sea, and the southwestern seashores are suffering from a growing land subsidence problem caused by the excessive extraction of groundwater. There is also very serious intrusion by seawater along the coastline. These circumstances obstruct any land use, soil remediation or agriculture development in the area. When seawater intrudes, salt gets into the soil. The infiltration, evapotranspiration and the distribution of salinity in the unsaturated soil become a very complex problem. It is vital to investigate the hysteresis of soil water‐retention curves, combined with the salinity in these areas. Therefore, this study's main focus will be the calibration of variations in salinity and their effect on the hysteresis of soil water‐retention curves. In the wetting processes, the salty soil water‐retention curves undergo an upper shift compared with the original soil water‐retention curves because of the higher tension of saltwater. In the drying processes, there is also an upper shift compared with the original curves because the salinity influences the air‐entry pressure. The saltwater's high salinity causes the hysteresis of soil water‐retention curves to experience a greater shift. The changes in salinity also cause changes to the hysteresis curves’ shape factors, which conforms to Huang's model (developed by Huang H.C., Y.C. Tan, C.W. Liu, and C.H. Chen in 2005), the values of α and n. The value of α decreases with the increased salinity. The trend of the n value presents an irregular result. A linear regression of the αw and αd values was advanced where the R‐square values of αw and αd exceeded 0.97. Copyright © 2012 John Wiley & Sons, Ltd.
On the role of surface roughness in the corrosion of pure magnesium in vitro
Authors: Nguyen T. L. , Blanquet A. , Staiger M. P. , Dias G. J. , Woodfield T. B. F.
Published: May 2012

The relationship between surface roughness and degradation behavior in magnesium (Mg) biomaterials is still a controversial issue. This study aims to clarify the relationship between surface roughness and corrosion rate of pure Mg. Pure Mg samples with surface roughness values (Ra) of 0.59, 2.68, and 9.12 μm were cast using an indirect solid‐free form fabrication method. The in vitro corrosion behavior was evaluated using hydrogen evolution, mass loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. It was confirmed that surface roughness had a significant influence on the corrosion rate of pure Mg, with increasing roughness resulting in an accelerated corrosion rate. However, pitting corrosion was not observed, suggesting that surface roughness does not affect the pitting potential of Mg. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Antibacterial effect of a resin incorporating a novel polymerizable quaternary ammonium salt MAE‐DB against Streptococcus mutans
Authors: Huang Li , Sun Xiang , Xiao Yu‐Hong , Dong Yan , Tong Zhong‐Chun , Xing Xiao‐Dong , Li Fang , Chai Zhi‐Guo , Chen Ji‐Hua
Published: May 2012

The antibacterial properties of resins incorporating MAE‐DB and the underlying mechanisms of action were evaluated. Antibacterial effects against Streptococcus mutans were tested using the film contact method, with accumulation and membrane integrity observed by scanning electron microscopy and confocal laser scanning microscopy, respectively. Quantitative PCR was used to determine expression of the S. mutans glucosyltransferase B (gtfB) gene on the surface of resins containing 10% MAE‐DB. Bacterial growth was inhibited on resin containing 10% MAE‐DB as compared with the control at 1 day, 7 days, 30 days, or 180 days (p < 0.05). For the 10%‐MAE‐DB resin, no significant differences in bacterial viability were found regardless of the time of incubation (p > 0.05). The number of bacteria attached to resin containing 10% MAE‐DB was considerably lower than the control. The proportion of bacteria with damaged cell membranes was increased in the experimental resin over controls. Expression of gtfB was reduced by 10% MAE‐DB compared with the control (p < 0.05). These findings demonstrate that MAE‐DB can be incorporated into resin materials at sufficient concentrations for long‐term antibacterial effects against S. mutans after polymerization by attenuating gtfB expression and impairing membrane integrity. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Efficient transfer of human adipose‐derived stem cells by chitosan/gelatin blend films
Authors: Cheng Nai‐Chen , Chang Hsu‐Hsien , Tu Yuan‐Kun , Young Tai‐Horng
Published: May 2012

Adipose‐derived stem cells (ASCs) are a potential source of abundant mesenchymal stem cells and represent a promising cell‐based therapy for tissue damage or degeneration conditions. Previous investigations have demonstrated enhanced therapeutic effects of ASCs in a three‐dimensional spheroid culture formulation. In this study, we hypothesize that a composite membrane made of chitosan/gelatin (C/G) is beneficial to facilitate transfer of human ASCs in spheroids. Increasing chitosan content within the blends enhanced the mechanical properties of the sample, including tensile strength and elongation‐at‐break ratio. Although ASC spheroids developed shortly after seeding on pure chitosan films, increasing gelatin proportion in the C/G blends promoted cell adhesion onto the membranes. We also found that ASCs did not proliferate on chitosan films, but C/G blends of different ratios supported ASC proliferation in the first 4 days of culture. However, ASCs on all C/G blends started to detach from the films to form spheroids after day 4, while ASCs on pure gelatin films remained attached and continued to grow. Gradual gelatin release from the C/G blend films, leading to enriched chitosan content in the blends, probably encouraged ASC detachment and spheroid formation. We placed porous collagen matrix on ASC‐seeded C/G blends to simulate the application of ASC‐seeded C/G films onto injured tissue and found that a C/G film composed of 75% chitosan could facilitate significantly more cell transfer into the overlying collagen sponge. Therefore, a blend film containing 75% chitosan and 25% gelatin showed promising results to serve as a biomaterial for human ASC‐based cell therapy. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B:, 2012.
Effect of amorphous calcium phosphate and silver nanocomposites on dental plaque microcosm biofilms
Authors: Cheng Lei , Weir Michael D. , Xu Hockin H. K. , Antonucci Joseph M. , Lin Nancy J. , Lin‐Gibson Sheng , Xu Sarah M. , Zhou Xuedong
Published: May 2012

A dental composite containing amorphous calcium phosphate nanoparticles (NACP) was developed that released calcium (Ca) and phosphate (PO4) ions and possessed acid‐neutralization capability. There has been little study on incorporation of antibacterial agents into calcium phosphate composites. The objective of this study was to investigate the effect of silver nanoparticle (NAg) mass fraction in NACP nanocomposite on mechanical properties and dental plaque microcosm biofilm for the first time. NACP nanoparticles of 116 nm were synthesized via a spray‐drying technique. NAg nanoparticles were synthesized using Ag 2‐ethylhexanoate and 2‐(tert‐butylamino)ethyl methacrylate, yielding NAg of particle size of 2.7 nm that were well‐dispersed in the resin. Five NACP nanocomposites were fabricated with NAg mass fractions of 0, 0.028, 0.042, 0.088, and 0.175%, respectively. Mechanical properties of NACP nanocomposites containing 0–0.042% of NAg matched those of a commercial composite without antibacterial activity. Live/dead assay of dental plaque microcosm biofilms showed complete coverage with live bacteria on commercial composite. However, there were increasingly more dead bacteria with higher NAg content in the NACP nanocomposite. Colony‐forming unit (CFU) counts for total microorganisms, total streptococci, and mutans streptococci for NACP nanocomposite with 0.042% NAg were about 1/4 those of commercial composite. Lactic acid production on NACP nanocomposite with 0.042% NAg was 1/3 that on commercial composite. In conclusion, novel NACP–NAg nanocomposites were developed which possessed good mechanical properties and potent antibacterial properties, with substantially reduced biofilm viability and lactic acid production. Hence, the NACP–NAg nanocomposites are promising for dental restorations with remineralizing and antibacterial capabilities. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B:000–000, 2012
Development of biodegradable polyurethane and bioactive glass nanoparticles scaffolds for bone tissue engineering applications
Authors: de Oliveira Agda Aline Rocha , de Carvalho Sandhra Maria , de Fátima Leite Maria , Oréfice Rodrigo Lambert , de Magalhães Pereira Marivalda
Published: May 2012

The development of polymer/bioactive glass has been recognized as a strategy to improve the mechanical behavior of bioactive glass‐based materials. Several studies have reported systems based on bioactive glass/biopolymer composites. In this study, we developed a composite system based on bioactive glass nanoparticles (BGNP), obtained by a modified Stöber method. We also developed a new chemical route to obtain aqueous dispersive biodegradable polyurethane. The production of polyurethane/BGNP scaffolds intending to combine biocompatibility, mechanical, and physical properties in a material designed for tissue engineering applications. The composites obtained were characterized by structural, biological, and mechanical tests. The films presented 350% of deformation and the foams presented pore structure and mechanical properties adequate to support cell growth and proliferation. The materials presented good cell viability and hydroxyapatite layer formation upon immersion in simulated body fluid. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Surface chemistry of bulk nanocrystalline pure iron and electrochemistry study in gas‐flow physiological saline
Authors: Nie F. L. , Zheng Y. F.
Published: May 2012

Conventional microcrystalline pure iron (MC‐Fe) becomes a new candidate as biodegradable metals, which has the insufficient physical feature and inferior biodegradation behavior. Novel bulk nanocrystalline pure iron (NC‐Fe) was fabricated via equal channel angular pressing technique in the present work to overcome these problems. The contact angle test with water and glycerol droplets shows a smaller angle (though >90°) of NC‐Fe than that of MC‐Fe, which implies a lower surface energy of NC‐Fe. The surface roughness of NC‐Fe increased greatly than that of MC‐Fe. A further comparative study of corrosion and electrochemistry performance between NC‐Fe and its original MC‐Fe was investigated in physiological saline with different dissolved oxygen concentration, aiming to in vitro simulate the corrosion process of coronary stent occurred in physiological environment. The electrochemical impedance spectra analysis and anodic polarization measurements indicated that the NC‐Fe exhibited higher corrosion resistance than that of the MC‐Fe; meanwhile obvious enhanced corrosion resistance with the decrement of dissolved oxygen concentration was observed. Related equivalent circuit model and surface reconstruction process were further discussed, and the degradation mechanism of the MC‐Fe and NC‐Fe were finally established. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
The dynamics of PKC‐induced phosphorylation triggered by Ca2+ oscillations in mouse eggs
Authors: Gonzalez‐Garcia Jose Raul , Machaty Zoltan , Lai F. Anthony , Swann Karl
Published: May 2012

Fertilization of mammalian eggs is characterized by a series of Ca2+ oscillations triggered by a phospholipase C activity. These Ca2+ increases and the parallel generation of diacylglycerol (DAG) stimulate protein kinase C (PKC). However, the dynamics of PKC activity have not been directly measured in living eggs. Here, we have monitored the dynamics of PKC‐induced phosphorylation in mouse eggs, alongside Ca2+ oscillations, using fluorescent C‐kinase activity reporter (CKAR) probes. Ca2+ oscillations triggered either by sperm, phospholipase C zeta (PLCζ) or Sr2+ all caused repetitive increases in PKC‐induced phosphorylation, as detected by CKAR in the cytoplasm or plasma membrane. The CKAR responses lasted for several minutes in both the cytoplasm and plasma membrane then returned to baseline values before subsequent Ca2+ transients. High frequency oscillations caused by PLCζ led to an integration of PKC‐induced phosphorylation. The conventional PKC inhibitor, Gö6976, could inhibit CKAR increases in response to thapsigargin or ionomycin, but not the repetitive responses seen at fertilization. Repetitive increases in PKCδ activity were also detected during Ca2+ oscillations using an isoform‐specific δCKAR. However, PKCδ may already be mostly active in unfertilized eggs, since phorbol esters were effective at stimulating δCKAR only after fertilization, and the PKCδ‐specific inhibitor, rottlerin, decreased the CKAR signals in unfertilized eggs. These data show that PKC‐induced phosphorylation outlasts each Ca2+ increase in mouse eggs but that signal integration only occurs at a non‐physiological, high Ca2+ oscillation frequency. The results also suggest that Ca2+‐induced DAG formation on intracellular membranes may stimulate PKC activity oscillations at fertilization. J. Cell. Physiol. 228: 110–119, 2013. © 2012 Wiley Periodicals, Inc.
Angiotensin type 1 receptor autoantibody from preeclamptic patients induces human fetoplacental vasoconstriction
Authors: Zhang Suli , Zheng Ronghua , Yang Lihong , Zhang Xi , Zuo Lin , Yang Xiaoli , Bai Kehua , Song Li , Tian Jue , Yang Jie , Liu Huirong
Published: May 2012

Increased vascular resistance in the fetoplacental circulation is a characteristic of preeclampsia. However, the potential molecular mechanisms of this condition remain obscure. The current study aimed to determine the direct effect of the peptide antigen corresponding to the second extracellular loop of the angiotensin II type 1 receptor (AT1R‐ECII) activating autoantibody (AT1‐AA), a novel risk factor in preeclamptic patients, on fetoplacental villus stem blood vessels. Immunohistochemistry revealed that AT1 receptors were localized in the veins and arteries of human placental villi. Among 58 serum samples from preeclamptic patients, 28 (48.28%) were proved AT1‐AA‐positive by enzyme‐linked immunosorbent assay [P < 0.01 vs. 2/51 (3.92%) in the normal pregnancy group]. Total IgGs purified from AT1‐AA‐positive patients' sera (AT1‐AA‐IgGs) were added to isolated normal human placental blood vessels. The IgG significantly constricted both the villus veins and arteries in a dose‐dependent manner in vitro, which could be blocked by the peptide corresponding to the human AT1R‐ECII, anti‐human IgG or the AT1 receptor antagonist losartan. Additionally, the venous constriction induced by AT1‐AA‐IgGs remained unchanged even at the end of the experiment (about half an hour), but the vasoconstriction caused by the AT1 receptor agonist angiotensin II underwent desensitization within three minutes. Collectively, our results demonstrated that AT1‐AA in preeclamptic sera can directly constrict fetoplacental villus blood vessels without desensitization via the AT1 receptor in vitro, which might contribute to poor fetoplacental perfusion in preeclampsia. J. Cell. Physiol. 228: 142–148, 2013. © 2012 Wiley Periodicals, Inc.
Acute appendagitis of the ligamentum teres hepatis: Clinical, ultrasound, and computed tomographic findings
Authors: Nolthenius Charlotte J. Tutein , Bruinsma Wendy E. , Knook M. T. T. , Puylaert Julien B. C. M.
Published: May 2012

Purpose.

To describe the clinical, ultrasound (US), and CT findings in three patients with acute appendagitis of the ligamentum teres hepatis.

Methods.

A retrospective search of cases over a 4‐year period was performed and yielded three patients with acute appendagitis of the ligamentum teres hepatis. The diagnosis was confirmed by US, CT, and clinical follow‐up in all three cases. We retrospectively noted the laboratory data, clinical findings, and presumptive clinical diagnosis and describe the US and CT findings.

Results.

All three patients presented with severe, circumscribed epigastric pain without other symptoms. The complex reactive protein was not elevated or only mildly elevated. At the spot of maximum pain, US and CT showed all signs of an acute appendagitis; however, the pain was not close to colon, but close to the teres ligament. Symptoms resolved within 1 to 2 weeks without therapy.

Conclusions.

Acute appendagitis of the teres ligament is not as rare as previously assumed. Familiarity with the US and CT features enables a reliable diagnosis and prevents unnecessary medical or operative treatment. © 2012 Wiley Periodicals, Inc. J Clin Ultrasound, 2013
Cerebrovascular response to valsalva maneuver: Methodology, normal values, and retest reliability
Authors: Wallasch Thomas‐Martin , Kropp Peter
Published: May 2012

Purpose.

To provide reference values of cerebrovascular reactivity measured with transcranial Doppler ultrasonography in response to rapid changes in blood pressure during the late straining phase (IIb) of a Valsalva maneuver (VM).

Methods.

Middle cerebral artery blood flow velocity, arterial blood pressure changes, and end‐tidal partial carbon dioxide pressure (pCO2) concentrations were simultaneously and noninvasively measured in 60 healthy subjects. Centro‐peripheral Valsalva ratio was calculated by the quotient of cerebrovascular reactivity and peripheral arterial blood pressure response to VM during phase IIb. Age dependency and short‐ and long‐term reliability of indices were evaluated. Correlation between the autonomic response and changes of pCO2 was calculated.

Results.

Centro‐peripheral Valsalva ratio was higher in younger healthy subjects, whereas peripheral autonomic reactivity appeared age‐independent. There was no correlation between dynamic autoregulatory response and pCO2. Short‐ and long‐term measurements of autoregulatory indices showed excellent reliability.

Conclusions.

VM is a suitable maneuver to evaluate dynamic autonomic response using transcranial Doppler ultrasonography and noninvasive arterial blood pressure monitoring. Autonomic response during VM does not depend on pCO2. Normal human subjects show age‐dependent centro‐peripheral autoregulatory response. 2012 Wiley Periodicals, © Inc. J Clin Ultrasound, 2012
Liver MRI and histological correlates in chronic liver disease on multiphase gadolinium‐enhanced 3D gradient echo imaging
Authors: Martin Diego R. , Lauenstein Thomas , Kalb Bobby , Lurie Christina , Kitajima Hiroumi , Sharma Puneet , Salman Khalil , Moreira Roger , Farris Alton B. , Spivey James , Martinez Enrique , Hanish Steve , Adsay Volkan
Published: May 2012

Purpose:

To evaluate intrinsic hepatic enhancement patterns on multiphase, gadolinium‐enhanced, fat‐suppressed, 3D T1‐weighted, gradient echo magnetic resonance imaging (MRI) as a quantitative correlate for severity of pathological changes in chronic liver disease (CLD).

Materials and Methods:

This study was HIPAA‐compliant and Institutional Review Board‐approved. In all, 75 patients were studied by contrast‐enhanced multiphase abdominal MRI. CLD patients had liver histology correlation derived from right lobe liver biopsies. Contrast‐enhanced arterial‐ and delayed‐phase 3D gradient recalled echo (GRE) liver MRI were scored using feature categorization templates to quantify enhancement patterns by three independent readers. Liver histopathology was staged/graded for fibrosis/inflammation using the Scheuer system. Statistical testing for MRI histology correlates used a Pearson's product moment correlation and a Wilcoxon–Mann–Whitney two‐sample rank‐sum test. Reader agreement was analyzed by a modified Fleiss' kappa test.

Results:

MRI histology correlation was high for delayed‐phase MRI versus fibrosis stage (95% confidence interval [CI] 0.941 < r < 0.976, P = 5 × 10−7), but lower for all other comparisons (delayed‐phase vs. inflammation and arterial‐phase vs. inflammation or fibrosis all showed a CI no greater than 0.64). Paired testing between delayed‐phase MRI score and histology fibrosis staging incremental levels was significant (from P < 10−2 to P < 10−5).

Conclusion:

A standard gadolinium‐enhanced liver MRI may provide a correlate measure of hepatic fibrosis over a spectrum of severity. J. Magn. Reson. Imaging 2012;36:422–429. © 2012 Wiley Periodicals, Inc.
Non‐contrast‐enhanced MRI of the pulmonary blood volume using two‐compartment‐modeled T1‐relaxation
Authors: Gaass Thomas , Dinkel Julien , Bauman Grzegorz , Zaiss Moritz , Hintze Christian , Haase Axel , Laun Frederik
Published: May 2012

Purpose:

To introduce a novel technique, based on a two‐compartment model and nonselective inversion recovery (TCIR) for the non‐contrast‐enhanced evaluation of the fractional pulmonary blood volume (fPBV).

Materials and Methods:

Ten healthy volunteers and one patient with focal lung destruction underwent examination with conventional magnetic resonance imaging (MRI) and TCIR. The reproducibility of TCIR was evaluated statistically, analyzing three consecutive measurement series. In order to evaluate the sensitivity of TCIR, the influence of gravitation on fPBV values along the anterior–posterior direction was assessed. Therefore, two transverse parameter maps of each volunteer in supine and prone position were acquired and analyzed. A comparison of patient images from TCIR‐MRI, dynamic contrast‐enhanced (DCE) MRI, and contrast‐enhanced computed tomography (CT) was performed visually.

Results:

The statistical evaluation showed significant similarity within the volunteer group, proving reproducibility. The detected slope of the fPBV values in anterior–posterior direction for both supine and prone position demonstrated the sensitivity of TCIR to the gravitational effect on the pulmonary blood distribution. The comparison between CT, DCE‐, and TCIR‐MRI patient datasets showed high similarity in dimension and location of the pathological part of the lung parenchyma.

Conclusion:

The introduced TCIR‐technique is able to provide reproducible maps of the fPBV without the application of intravenous contrast media. J. Magn. Reson. Imaging 2012;36:397–404. © 2012 Wiley Periodicals, Inc.
Feasibility of in ovo diffusion tractography in the chick embryo using a dual‐cooling technique
Authors: Zhou Zien , Xu Jianrong , DelProposto Zachary S. , Hua Jia , Fan Yunshu , Zhang Zishu , Ye Yongquan , Haacke E.Mark , Hu Jiani
Published: May 2012

Purpose:

To evaluate the capability of a dual‐cooling technique in suppressing motion artifact and to evaluate the feasibility of the noninvasive muscle fibers tracking using DTI during chick embryonic development.

Materials and Methods:

Fifteen eggs were divided into three groups of 5 eggs each (one group for each imaging sequence), and eggs were imaged every 48 h from incubation day 4; embryos were imaged in ovo using three sequences of varying duration (T1, T2, and DTI). For each sequence, three preprocessing methods were used: no‐cooling (NC), single‐cooling (SC), and dual‐cooling (DC). Two independent observers assessed images for motion artifact. The results of different preprocessing methods used for each sequence were compared by the χ2 test. The Cohen kappa test was used to assess the interobserver variability.

Results:

For T1 imaging, motion artifact was adequately suppressed by both SC and DC methods (χ2 test; P > 0.05). For T2 imaging, motion artifact was also sufficiently suppressed by both SC and DC methods (χ2 test; P > 0.05) except incubation day 19 (χ2 test; P < 0.001). For DTI, motion artifact was less with DC than SC after 8 days (χ2 test; P < 0.05). Hindlimb muscle fibers of chick embryo could be serially evaluated with DTI from 8 days using dual‐cooling technique.

Conclusion:

The dual‐cooling technique enables DTI of chick embryo in ovo with minimal motion artifact, which permits muscle fiber tracking by DTI during chick embryonic development possible, and can improve the imaging quality of conventional MRI with long duration and those sensitive to motion. J. Magn. Reson. Imaging 2012;36:993–1001. © 2012 Wiley Periodicals, Inc.
The devil without and within: A conceptual model of social cognitive processes whereby discrimination leads stigmatized minorities to become discouraged workers
Authors: Heslin Peter A. , Bell Myrtle P. , Fletcher Pinar O.
Published: May 2012

In contrast to the substantial literatures on job loss, underemployment, and re‐employment, management scholars have paid scant attention to “discouraged workers,” defined as those who want to work but have ceased looking for work because of labor market‐related reasons such as discrimination. Drawing together the labor economics category of discouraged workers, the diversity literature on employment discrimination, and social cognitive research on careers, we model social cognitive mechanisms whereby discrimination can lead stigmatized minorities to become discouraged workers. We show how direct effects of discrimination (the “devil without”) can be compounded by its indirect impacts—through minority socialization and identity, struggling role models, learned helplessness, and low job search self‐efficacy (collectively, the “devil within”)—to lead stigmatized minorities to become discouraged workers. Our model of insidious intra‐ and inter‐personal dynamics that can amplify and sustain the demoralization and exclusion that stems from discrimination has implications for researchers, organizations, and those concerned with helping discouraged workers. Copyright © 2012 John Wiley & Sons, Ltd.
Clinical use of a neck brace to improve hands‐free speech in laryngectomized patients
Authors: Dirven Richard , Kooijman Piet G. C. , Wouters Yannick , Marres Henri A. M.
Published: May 2012

Objectives/Hypothesis:

Time of adherence of adhesive baseplate housings to the neck of a laryngectomized patient is one of the main problems that account for the low number of laryngectomy patients who benefit from hands‐free speech. An external neck brace (ENB 1.0) was introduced to support peristomal fixation of adhesive baseplates.

Study Design:

A prospective randomized controlled clinical cross‐over trial.

Methods:

A total of 28 laryngectomy patients participated in this randomized, prospective, crossover trial. All used the Provox hands‐free heat and moisture exchanger (HME) valve for 1 month: 2 weeks with an ENB and 2 weeks without.

Results:

The median lifetime of an adhesive baseplate without a brace was 52.5 minutes versus 210 minutes with a brace (P = .03). Four participants considered the ENB as “a little” bit of a welcome addition, nine as “quite a bit,” and six as “very much” (79%) to improve hands‐free speech.

Conclusions:

The ENB significantly increases the lifetime of an adhesive baseplate and therefore contributes to achieving hands‐free speech for a greater number of patients with laryngectomy. Laryngoscope, 2012
Genetic and clinical characteristics of head and neck paragangliomas in a chinese population
Authors: Zheng Xiangqian , Wei Songfeng , Yu Yang , Xia Tingting , Zhao Jing , Gao Songyuan , Li Yigong , Gao Ming
Published: May 2012

Objectives/Hypothesis:

Head and neck paragangliomas (PGLs) are rare and frequently associated with germline mutations of the succinate dehydrogenase (SDH) genes, especially for familial cases. The purpose of the study was to explore genetic and clinical characteristics of head and neck PGLs in a Chinese population.

Study Design:

Retrospective review.

Methods:

One hundred thirty‐two patients who had undergone resection for head and neck PGLs between 1975 and 2010 were identified. Clinical characteristics and outcomes were reviewed. Analysis of the SDH genes was performed in 29 patients and one kindred with familial PGL to identify germline mutations in the SDHB, SDHC, and SDHD genes by direct DNA sequencing.

Results:

There were 69 male (52.3%) and 63 female (47.76%) patients, with a mean age of 43.6 years (range, 13–72 years). Most lesions (61.4%) were PGLs of the carotid bifurcation. Others included jugular (25.0%), vagal (9.1%), and tympanic PGLs. Twenty‐one patients (15.9%) had multiple PGLs, 25 patients (18.9%) had a malignant PGL, and 15 patients (11.4%) in four families were familial PGLs. Analysis of the SDH genes in 29 patients showed that four familial cases (including two patients) carried a heterozygotic missense mutation in SDHD. The mutation was W43X, located in SDHD‐exon 2. Four sporadic cases carried samesense germline mutations in SDHB‐exon 1, and they were all malignant PGLs.

Conclusions:

Multifocal occurrence, potential malignancy, and genetic aspect should be considered in patients with head and neck PGLs. The high frequency of founder mutations in SDHB suggests a higher prevalence of malignancy, and the SDHD mutation is usually associated with familial cases. Laryngoscope, 2012