bluuebunny/crossref_metadata_2025 huggingface dataset:
LC‐MS/MS as an alternative for SDS‐PAGE in blue native analysis of protein complexes
Authors: Wessels Hans J. C. T. , Vogel Rutger O. , van den Heuvel Lambert , Smeitink Jan A. , Rodenburg Richard J. , Nijtmans Leo G. , Farhoud Murtada H.
Published: August 2009

Two‐dimensional blue native/SDS‐PAGE is widely applied to investigate native protein–protein interactions, particularly those within membrane multi‐protein complexes. MS has enabled the application of this approach at the proteome scale, typically by analysis of picked protein spots. Here, we investigated the potential of using LC‐MS/MS as an alternative for SDS‐PAGE in blue native (BN) analysis of protein complexes. By subjecting equal slices from BN gel lanes to label‐free semi‐quantitative LC‐MS/MS, we determined an abundance profile for each protein across the BN gel, and used these profiles to identify potentially interacting proteins by protein correlation profiling. We demonstrate the feasibility of this approach by considering the oxidative phosphorylation complexes I–V in the native human embryonic kidney 293 mitochondrial fraction, showing that the method is capable of detecting both the fully assembled complexes as well as assembly/turnover intermediates of complex I (NADH:ubiquinone oxidoreductase). Using protein correlation profiling with a profile for subunits NDUFS2, 3, 7 and 8 we identified multiple proteins possibly involved in the biogenesis of complex I, including the recently implicated chaperone C6ORF66 and a novel candidate, C3ORF60.
Comparative proteome analysis of porcine follicular fluid and serum reveals that excessive α2‐macroglobulin in serum hampers successful expansion of cumulus‐oocyte complexes
Authors: Bijttebier Jo , Tilleman Kelly , Dhaenens Maarten , Deforce Dieter , Van Soom Ann , Maes Dominiek
Published: August 2009

Porcine follicular fluid (pFF) constitutes the micro‐environment of the maturing oocyte. Although pFF is a transudate of serum, in pigs, it is superior to serum in promoting in vitro expansion of the cumulus cells, a specialized cell population surrounding the oocyte. A comparative proteome analysis of autologous serum and pFF was performed to investigate proteins involved in successful cumulus expansion of porcine oocytes. iTRAQ labeling followed by 2‐D LC ESI‐Q‐TOF MS/MS revealed 63 proteins common to both fluids of which the abundance of 13 proteins was significantly different (p<0.05). Seven proteins were more concentrated in serum whereas six proteins were more abundant in pFF. To investigate the importance of these proteins, the cumulus matrices of COCs were collected after in vitro maturation in media supplemented with either of both biologically fluids and then subjected to 2‐D PAGE analysis. α2‐Macroglobulin and CH4 and secrete domains of swine IgM, which were both less abundant in pFF, were absent from cumulus matrix extracts after in vitro maturation in pFF. Although both proteins were incorporated in the matrices of cumulus‐oocyte complexes matured in serum, depletion of α2‐macroglobulin from serum could significantly compensate for the impaired cumulus expansion of oocytes matured in serum.
Rapid selection of peptide containing fractions in off‐line 2‐D HPLC in shotgun proteome analysis by screening with MALDI TOF MS
Authors: Lasaosa Maria , Jakoby Thomas , Delmotte Nathanaël , G. Huber Christian , Heinzle Elmar , Tholey Andreas
Published: August 2009

A simple and fast screening method for the selection of fractions of first dimension separation to be analyzed in second dimension‐MS/MS experiments in offline multidimensional liquid chromatographic separation schemes for shotgun proteome analysis was developed. The method is based on the measurement of total peptide content of the first dimension fractions by MALDI MS and was established using a tryptic digest of a bacterial proteome. The results of the screening process were in good agreement with those obtained in a detailed proteome analysis performed by RP×ion‐pair RP‐MALDI TOF/TOF MS analysis. The method supports a straightforward planning of experiments, also enabling a reduction of overall measurement time in shotgun proteome analysis.
Spectroscopic (FT‐IR, FT‐Raman, UV, 1H, and 13C NMR) and theoretical studies of m‐anisic acid and lithium, sodium, potassium, rubidium, and caesium m‐anisates
Authors: Kalinowska M. , Świsłocka R. , Rzączyńska Z. , Sienkiewicz J. , Lewandowski W.
Published: August 2009

In order to understand the nature of the interactions of biologically important ligands, it is necessary to carry out the physico‐chemical studies of these compounds with their biological targets (e.g., receptors in the cell or important cell components). Results of this study make it possible to predict some properties of a molecule, such as its reactivity, durability of complex compounds, and kinship to enzymes. In this paper the effect of alkali metal cations (Li, Na, K, Rb, and Cs) on the electronic structure of m‐methoxybenzoic acid (m‐anisic acid) was studied. The experimental IR (in solid state and solution), Raman, UV (in solid state and solution), 1H, and 13C NMR spectra of m‐methoxybenzoic acid, and its salts were registered, assigned, and analyzed. Some of the obtained results were compared with published data for o‐anisic acid and o‐anisates. The structures of anisic acid and Li, Na, and K m‐anisates were optimized at the B3LYP/6‐311++G** level. The IR, 1H, and 13C NMR spectra and NPA, ChelpG, and MK atomic charges were calculated. The change of metal along with the series: Li → Na → K → Rb → Cs caused: (1) the change in the electronic charge distribution in anisate anion that is seen via the occurrence of the systematic shifts of several bands in the experimental and theoretical IR and Raman spectra of anisates; (2) systematic 1H and 13C NMR chemical shifts; (3) hypsochromic shifts in UV spectra of salts as compared to ligands. Copyright © 2009 John Wiley & Sons, Ltd.
Conformations and enthalpies of formation of methylenecyclohexane, 1,4‐dimethylenecyclohexane, cyclohexanone, 4‐methylenecyclohexanone, 1,4‐cyclohexanedione, and their mono‐ and dioxa derivatives by G3(MP2)//B3LYP calculations
Authors: Taskinen Esko
Published: August 2009

A computational study of the stable conformations and gas‐phase enthalpies of formation at 25 °C of the title compounds has been carried out by G3(MP2)//B3LYP calculations. The work stems from our early observations on the thermodynamic and NMR spectroscopic properties of 2‐methylenetetrahydropyran and related compounds suggesting a dominating chair conformation, with poor p–π overlap in the OCC moiety, for these compounds. Besides computational verification of the chair conformation of 2‐methylenetetrahydropyran, the work was extended to find out the stable conformations of a number of other related compounds and to evaluate the relative stabilities of the various conformers. Another important goal of the work was the estimation of the gas‐phase enthalpies of formation of the present compounds, for which such literature data are scarce. A significant error in the literature value of the enthalpy of formation of methylenecyclohexane was found. Finally, the relative enthalpy levels of the isomeric compounds of this work are discussed. The high thermodynamic stability of the compounds containing an ester functional group, OCO, relative to the stability of isomeric compounds with an OCC moiety in place of the ester function, is demonstrated. Copyright © 2009 John Wiley & Sons, Ltd.
DFT study of the 1,3‐dipolar cycloaddition of azomethine ylides with maleimide, maleic anhydride, methylacrylate and some simple substituted alkenes
Authors: Das Tapas Kumar , Banerjee Manas
Published: August 2009

DFT calculations involving the B3LYP functional and 6‐31G(d) basis set have been performed to rationalize the reactivity, regioselectivity, enantioselectivity and diasteriofacial selectivity in the context of 1,3‐dipolar cycloaddition (13DC) reactions of a few acyclic and two cyclic azomethine ylides (AY) leading to enantiomeric/ diasteriomeric excess of the products. In particular, N‐substituted and C‐substituted AYs have been considered for reactions with the substituted ethylenes, maleimide, maleic anhydride and methyl acrylate. From an analysis of the results of calculation for the selected reactions, the regio‐ and exo/endo‐stereoselectivity have been explained. Reactions were followed through transition state (TS) structure optimization, calculation of IRC and activation energies. A rationalization of the trends in regioselectivity and enantioselectivity was attempted with the help of HOMO–LUMO energies, electrophilicity differences (Δω) and an analysis of Pauling's bond order (PBO) in the TS. Copyright © 2009 John Wiley & Sons, Ltd.
‘Locking and unlocking control’ of photochromism of naphthopyran derivative
Authors: Guo Kunpeng , Chen Yi
Published: August 2009

A ‘locking and unlocking control’ for a photochromic molecular system has been developed by using a photochromic naphthopyran derivative 1a as the model compound. With UV light irradiation, the colorless solution of 1a underwent ring‐opening photoisomerization and converted to a purple solution 1b, which quickly faded back to a colorless solution with visible light (λ ≥ 480 nm) irradiation or in the dark. Addition of boron trifluoride diethyl etherate to the solution of 1b produced a complex compound 2b, accompanying the color change from purple to blue. It was found that 2b remained photochemically inactive. With the addition of diethanolamine, however, the ‘locked’ photoreaction of 2b could be unlocked and converted back to 1b, in which the photochromism was recovered. Copyright © 2009 John Wiley & Sons, Ltd.
BuildBeta—A system for automatically constructing beta sheets
Authors: Max Nelson , Hu ChengCheng , Kreylos Oliver , Crivelli Silvia
Published: August 2009

We describe a method that can thoroughly sample a protein conformational space given the protein primary sequence of amino acids and secondary structure predictions. Specifically, we target proteins with β‐sheets because they are particularly challenging forab initioprotein structure prediction because of the complexity of sampling long‐range strand pairings. Using some basic packing principles, inverse kinematics (IK), and β‐pairing scores, this method creates all possible β‐sheet arrangements including those that have the correct packing of β‐strands. It uses the IK algorithms of ProteinShop to move α‐helices and β‐strands as rigid bodies by rotating the dihedral angles in the coil regions. Our results show that our approach produces structures that are within 4–6 Å RMSD of the native one regardless of the protein size and β‐sheet topology although this number may increase if the protein has long loops or complex α‐helical regions. Proteins 2010. © Published 2009 Wiley‐Liss, Inc.
Comparative binding energy analysis for binding affinity and target selectivity prediction
Authors: Henrich Stefan , Feierberg Isabella , Wang Ting , Blomberg Niklas , Wade Rebecca C.
Published: August 2009

A major challenge in drug design is to obtain compounds that bind selectively to their target receptors and do not cause side‐effects by binding to other similar receptors. Here, we investigate strategies for applying COMBINE (COMparative BINding Energy) analysis, in conjunction with PIPSA (Protein Interaction Property Similarity Analysis) and ligand docking methods, to address this problem. We evaluate these approaches by application to diverse sets of inhibitors of three structurally related serine proteases of medical relevance: thrombin, trypsin, and urokinase‐type plasminogen activator (uPA). We generated target‐specific scoring functions (COMBINE models) for the three targets using training sets of ligands with known inhibition constants and structures of their receptor‐ligand complexes. These COMBINE models were compared with the PIPSA results and experimental data on receptor selectivity. These scoring functions highlight the ligand‐receptor interactions that are particularly important for binding specificity for the different targets. To predict target selectivity in virtual screening, compounds were docked into the three protein binding sites using the program GOLD and the docking solutions were re‐ranked with the target‐specific scoring functions and computed electrostatic binding free energies. Limits in the accuracy of some of the docking solutions and difficulties in scoring them adversely affected the predictive ability of the target specific scoring functions. Nevertheless, the target‐specific scoring functions enabled the selectivity of ligands to thrombin versus trypsin and uPA to be predicted. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Plasmodium falciparum acyl carrier protein crystal structures in disulfide‐linked and reduced states and their prevalence during blood stage growth
Authors: Gallagher John R. , Prigge Sean T.
Published: August 2009

Acyl Carrier Protein (ACP) has a single reactive sulfhydryl necessary for function in covalently binding nascent fatty acids during biosynthesis. In Plasmodium falciparum, the causative agent of the most lethal form of malaria, fatty acid biosynthesis occurs in the apicoplast organelle during the liver stage of the parasite life cycle. During the blood stage, fatty acid biosynthesis is inactive and the redox state of the apicoplast has not been determined. We solved the crystal structure of ACP from P. falciparum in reduced and disulfide‐linked forms, and observe the surprising result that the disulfide in the PfACP cross‐linked dimer is sequestered from bulk solvent in a tight molecular interface. We assessed solvent accessibility of the disulfide with small molecule reducing agents and found that the disulfide is protected from BME but less so for other common reducing agents. We examined cultured P. falciparum parasites to determine which form of PfACP is prevalent during the blood stages. We readily detected monomeric PfACP in parasite lysate, but do not observe the disulfide‐linked form, even under conditions of oxidative stress. To demonstrate that PfACP contains a free sulfhydryl and is not acylated or in the apo state, we treated blood stage parasites with the disulfide forming reagent diamide. We found that the effects of diamide are reversed with reducing agent. Together, these results suggest that the apicoplast is a reducing compartment, as suggested by models of P. falciparum metabolism, and that PfACP is maintained in a reduced state during blood stage growth. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Validation of spring operated pressure relief valve time‐to‐failure
Authors: Harris Stephen P. , Gross Robert E.
Published: August 2009

The Savannah River Site operates a relief valve repair shop certified by the National Board of Pressure Vessel Inspectors. Local maintenance forces perform inspection, testing, and repair of ∼1,200 spring‐operated relief valves each year as the valves are cycled in from the field.

The Site now has over 7,000 certified test records in the Computerized Maintenance Management System; a summary of that data is presented in this article. In previous articles, several statistical techniques were used to investigate failure on demand and failure rates including a quantal response method for predicting the probability of failure. The nonconservative failure mode is commonly termed “stuck shut”; industry defined as the valve opening at greater than or equal to 1.5 times the cold set pressure. Actual time‐to‐failure is typically not known, only that failure occurred some time since the last proof test.

The resulting Monte Carlo simulation in this article shows that previous conclusions on the statistical lifetime predictions and failure studies were not as conservative as initially thought. Our simulations use an aging model for lift pressure increase as a function of set pressure, valve manufacturer, and time. This article attempts to answer two questions: (a) what is the predicted failure rate over the chosen maintenance/inspection interval, and (b) do we understand aging and variability sufficiently to estimate risk when basing proof test intervals on proof test results? © 2009 American Institute of Chemical Engineers Process Saf Prog 2010
Flammability characteristics of HFO‐1234yf
Authors: Minor Barbara H. , Herrmann David , Gravell Robert
Published: August 2009

A new low global warming refrigerant, CF3CF=CH2(HFO‐1234yf), has been developed to replace HFC‐134a in automotive air conditioning systems. HFC‐134a is being phased out in the European Union due to high global warming potential. HFO‐1234yf is highly energy efficient, exhibits low toxicity, and can potentially be used in systems currently designed for refrigerant HFC‐134a with minimal modifications. Significant work has been completed to assess the flammability characteristics of HFO‐1234yf. Though it is flammable per ASTM E‐681, it is significantly less so than HFC‐152a which has also been considered as an HFC‐134a alternative. HFO‐1234yf has a relatively high lower flammability limit at 6.2 vol% in air. Computational Fluid Dynamics (CFD) modeling has shown it is very unlikely the lower flammability limit will be reached when the refrigerant is leaked into the passenger compartment of a vehicle. HFO‐1234yf also has a high minimum ignition energy (MIE) from 5,000 to 10,000 mJ which indicates there may be very few potential ignition sources in a vehicle. It also has very low burning velocity at 1.5 cm/sec indicating low potential for damage should an ignition occur. Several automotive industry groups have completed extensive risk assessments which have concluded HFO‐1234yf is safe to use as a refrigerant in vehicles. This article will review flammability test results and challenges that were overcome to measure flammability of a mildly flammable refrigerant as well as CFD modeling work for vehicle leakage scenarios. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2010
Cryogenic extinguishment of liquid pool fires
Authors: Levendis Yiannis , Ergut Ali , Delichatsios Michael
Published: August 2009

Results on fire extinguishment using direct application of liquid nitrogen are presented in this article. This technique targets challenging fires, such as burning hazardous chemicals or fuels, in which cases prompt suppression or extinguishment is paramount to prevent explosions, avoid release of toxic fumes and avert environmental catastrophes. Liquid nitrogen is a rather environmentally benign extinguishing agent that does not cause property damage or groundwater contamination. Application of this cryogen onto a hot pyrolyzing/burning surface induces abrupt vaporization, spread and expansion. The pyrolyzing gases are inerted, the surface is cooled and hence its pyrolysis rate is reduced, air is separated from the fuel, and the fire extinguishes. To demonstrate this technique, experiments were conducted with pool fires of ethanol, propanol, and diesel fuel. To examine the underlying principles, analysis of the results was conducted based on simplified calculations. Sufficient quantities of the cryogen extinguished the fires nearly instantaneously. Half‐liter quantities were sufficient to extinguish 1 m2 pool fires. The method of dispensing and distributing the cryogen on the pool fires proved to be of considerable importance. The existence of wind, which disturbed the flame, was not found to prevent extinguishment. © 2009 American Institute of Chemical Engineers Process Saf Prog 2010
Auxetic lattice of multipods
Authors: Pikhitsa Peter V. , Choi Mansoo , Kim Hyung‐Jung , Ahn Sung‐Hoon
Published: August 2009

Auxetics are novel counterintuitive materials that grow thicker perpendicularly to the applied force when stretched and therefore are described by a negative Poisson's ratio. We show that a regular lattice of individual multipods properly assembled in three dimensions has the ultimate negative Poisson's ratio −1: the lattice expands or contracts uniformly in all directions. Our ball‐and‐stick working model verifies the mathematical construction. Application of the model to real materials is discussed. Our result is important for understanding the ways to create entangled materials with interesting mechanical properties.
Mechanical properties of auxetic carbon/epoxy composites: static and cyclic fatigue behaviour
Authors: Bezazi A. , Boukharouba W. , Scarpa F.
Published: August 2009

This work describes the effect that stacking sequence lay‐ups have on the static and cyclic fatigue properties of T300/914 auxetic carbon/epoxy composites. Two laminate composites [±20]2S and [±25]2S providing a theoretical NPR effect through the thickness have been subjected to quasi‐static and cyclic fatigue under 3‐point bending. The static tests have shown that the stiffness and the maximum failure load decrease with increasing fibre orientation angles for the laminates. The fatigue tests also show that the stiffness degradations versus the number of cycles occur on tree stages, with significant energy dissipation recorded for the two auxetic specimens.
Stress–strain behavior in main chain liquid crystalline elastomers: effect of crosslinking density and transverse rod incorporation on “Poisson's ratio”
Authors: Ren Wanting , McMullan Philip J. , Griffin Anselm C.
Published: August 2009

Stress–strain results are reported for two series of smectic C main chain liquid crystalline elastomers (MCLCEs). The structural variable in one series is crosslink density; in the other, transverse rod content. With increasing crosslinker content, the LCEs exhibit increased modulus, a shorter polydomain‐to‐monodomain (P–M) plateau, and a lower elongation at break. Increasing transverse rod content leads to lower clearing temperatures and lower modulus. For each series, stress–strain measurement was made simultaneously with Poisson's ratio determination. For the variable crosslinker series, typical behavior showed the Poisson's ratio increased at small strain, rose to a maximum about 50% strain, then decreased with greater strain. For the transverse rod series, typical behavior also showed the Poisson's ratio increased at small strain, rose to a maximum about 50% strain, then decreased with greater strain. In both series, the maximum in the Poisson's ratio corresponded to the onset of the P–M transition. Possible deformation mechanisms are presented.
Process selection for higher production yield based on capability index Spk
Authors: Lin Chen‐ju , Pearn W. L.
Published: August 2009

Process selection is the problem of comparing two processes and selecting the one that has a higher capability value. In this paper, we consider the process selection problem by using the yield index Spk to compare two production processes and select one that has higher production yield. An analytical exact approach is proposed to solve this problem. Testing hypotheses with two phases for comparing two processes are developed. Critical values of the test are obtained to determine the selection decisions. Sample sizes required for designated selection power and confidence level are also investigated. The results provide useful information to practitioners. An application example on comparing two thin‐film transistor (TFT) type liquid‐crystal display (LCD) production processes is presented to illustrate the practicality of the proposed approach to a real problem in the factory. Copyright © 2009 John Wiley & Sons, Ltd.
Designing experiments for nonlinear models—an introduction
Authors: Johnson Rachel T. , Montgomery Douglas C.
Published: August 2009

We illustrate the construction of Bayesian D‐optimal designs for nonlinear models and compare the relative efficiency of standard designs with these designs for several models and prior distributions on the parameters. Through a relative efficiency analysis, we show that standard designs can perform well in situations where the nonlinear model is intrinsically linear. However, if the model is nonlinear and its expectation function cannot be linearized by simple transformations, the nonlinear optimal design is considerably more efficient than the standard design. Published in 2009 by John Wiley & Sons, Ltd.
Density functional investigations of endohedral metallofullerenes TM@C24 (TM = Mn, Fe, Co, Ni, Cu, and Zn)
Authors: Yue Yun , Li Xiao‐Jun
Published: August 2009

The theoretical investigations on TM@C24 (TM = Mn, Fe, Co, Ni, Cu, and Zn) with different spin configurations have been performed by using the hybrid DFT‐B3PW91 functional in conjunction with 6‐31G(d) basis sets. The results show that the ground states of Fe@C24 and Ni@C24 are their spin triplet states, whereas the ground state of Co@C24 is spin quartet state. Moreover, three Fe@C24 isomers are favorable in energy. The HOMO and LUMO of Zn@C24 indicates that there is no hybridization between Zn atomic orbitals and the C24 cage orbitals. Natural population analysis shows that the charges always transfer from the TM atoms to the C24 cage. In going from isolated TM atom to TM@C24, the occupation of the 4s orbital is strongly reduced. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Imaging and studying human topoisomerase I on mica surfaces in air and in liquid by atomic force microscopy
Authors: Liu Zhiguo , Meng Ronghua , Zu Yuangang , Li Qingyong , Yao Liping
Published: August 2009

In this study, the topography of human topoisomerase I (TOPO I) on mica surfaces in air and in liquid has been studied by atomic force microscopy (AFM). The average height of TOPO I on mica surface in air measured by AFM was 2.59±0.32 nm. After adsorption of the 0.3 U/µl TOPO I on mica surfaces for 2 h, and then imaged in liquid by AFM, well‐separated single TOPO I was observed. The average height of TOPO I on mica surfaces in liquid measured by AFM was 2.93±0.42 nm. After adsorption of the 4 U/µl TOPO I on mica surfaces for 1.5 h, TOPO I monolayer can be formed. The produced TOPO I monolayer on mica was flat and exhibited good stability. SCANNING 31: 160–166, 2009. © 2009 Wiley Periodicals, Inc.
Effects of fiber diameter and CO2 activation temperature on the pore characteristics of polyacrylonitrile based activated carbon nanofibers
Authors: Tavanai Hossein , Jalili Rouholah , Morshed Mohamad
Published: August 2009

The effects of fiber diameter and activation temperature on the pore characteristics of polyacrylonitrile based activated carbon nanofibers are investigated. It was found that lower fiber diameters as well as higher activation temperatures lead to a higher weight loss, specific surface area and total pore volume. The nitrogen adsorption capacity of activated carbon nanofibers is almost three times that of activated carbon fiber with a diameter of 10 µm. As far as the size of pores in activated carbon nanofibers is concerned, it is basically the micropores that dominate the scene. Moreover, tailoring the pore characteristics by adjusting the activation temperature and fiber diameter is plausible. Copyright © 2009 John Wiley & Sons, Ltd.
Nodal Signaling via an Autocrine Pathway Promotes Proliferation of Mouse Spermatogonial Stem/Progenitor Cells Through Smad2/3 andOct-4Activation
Authors: He Zuping , Jiang Jiji , Kokkinaki Maria , Dym Martin
Published: August 2009

Spermatogenesis is the process that involves the division and differentiation of spermatogonial stem cells into spermatozoa. However, the autocrine molecules and signaling pathways controlling their fate remain unknown. This study was designed to identify novel growth factors and signaling pathways that regulate proliferation, differentiation, and survival of spermatogonial stem/progenitor cells. To this end, we have for the first time explored the expression, function, and signaling pathway of Nodal, a member of the transforming growth factor-β superfamily, in mouse spermatogonial stem/progenitor cells. We demonstrate that both Nodal and its receptors are present in these cells and in a spermatogonial stem/progenitor cell line (C18-4 cells), whereas Nodal is undetected in Sertoli cells or differentiated germ cells, as assayed by reverse transcription-polymerase chain reaction, Western blots, and immunocytochemistry. Nodal promotes proliferation of spermatogonial stem/progenitor cells and C18-4 cells, whereas Nodal receptor inhibitor SB431542 blocks their propagation as shown by proliferation and bromodeoxyuridine incorporation assays. Nodal knockdown by RNA interference results in a marked increase of cell apoptosis and a reduction of cell division as indicated by terminal deoxynucleotidyl transferase dUTP nick-end labeling and proliferation assays. Conversely, overexpression of Nodal leads to an increase of cell proliferation. Nodal activates Smad2/3 phosphorylation, Oct-4 transcription, cyclin D1, and cyclin E expression, whereas SB431542 completely abolishes their increase. Together, Nodal was identified as the first autocrine signaling molecule that promotes proliferation of mouse spermatogonial stem/progenitor cells via Smad2/3 and Oct-4 activation. This study thus provides novel and important insights into molecular mechanisms regulating proliferation and survival of spermatogonial stem/progenitor cells.
Signaling Pathways Controlling Pluripotency and Early Cell Fate Decisions of Human Induced Pluripotent Stem Cells
Authors: Vallier Ludovic , Touboul Thomas , Brown Stephanie , Cho Candy , Bilican Bilada , Alexander Morgan , Cedervall Jessica , Chandran Siddharthan , Ährlund-Richter Lars , Weber Anne , Pedersen Roger A.
Published: August 2009

Human pluripotent stem cells from embryonic origins and those generated from reprogrammed somatic cells share many characteristics, including indefinite proliferation and a sustained capacity to differentiate into a wide variety of cell types. However, it remains to be demonstrated whether both cell types rely on similar mechanisms to maintain their pluripotent status and to control their differentiation. Any differences in such mechanisms would suggest that reprogramming of fibroblasts to generate induced pluripotent stem cells (iPSCs) results in novel states of pluripotency. In that event, current methods for expanding and differentiating human embryonic stem cells (ESCs) might not be directly applicable to human iPSCs. However, we show here that human iPSCs rely on activin/nodal signaling to control Nanog expression and thereby maintain pluripotency, thus revealing their mechanistic similarity to human ESCs. We also show that growth factors necessary and sufficient for achieving specification of human ESCs into extraembryonic tissues, neuroectoderm, and mesendoderm also drive differentiation of human iPSCs into the same tissues. Importantly, these experiments were performed in fully chemically defined medium devoid of factors that could obscure analysis of developmental mechanisms or render the resulting tissues incompatible with future clinical applications. Together these data reveal that human iPSCs rely on mechanisms similar to human ESCs to maintain their pluripotency and to control their differentiation, showing that these pluripotent cell types are functionally equivalent.

Disclosure of potential conflicts of interest is found at the end of this article.
Privatization in Saudi Arabia: Is slow beautiful?
Authors: Akoum Ibrahim
Published: August 2009

The aim of this article is to abridge the dearth of academic research on Saudi Arabia's privatization strategy, which is touted by government as key to empowering the business community in the largest economy in the Middle East and North Africa region. Whereas some contend privatization has moved at a slow pace and that the business model employed for privatizing public enterprises lacks commercial business efficiency standards, government retorts that, guided by an organized and sequential process, privatization has been successful. This article maintains that if privatization is to confer the benefits claimed for it and sway international investors equipped with modern managerial skills and technical know‐how, authorities need to accelerate privatization and subject enterprises to steadfast market competitive forces. © 2009 Wiley Periodicals, Inc.
Knowledge seeking in going abroad
Authors: Sallis James E. , Deo Sharma D.
Published: August 2009

Based on knowledge theories, this study examines the impact of client‐following and market‐seeking entry strategies on foreign market entry by firms. The article also explores the subsequent development of knowledge in firms. Using data from 116 firms, we test three hypotheses using logistic regression. Our hypotheses are supported in the data. Our analysis shows that significant differences exist between client‐following firms and market‐seeking firms. Client followers are both supported and trapped by their international network, whereas market seekers, though not supported, are much freer to pursue higher‐order learning. Due to differences in their network ties, these two types of firms learn at different speeds and learn different things. We also found that firms with proactive knowledge‐seeking strategies learn more. Thus, learning strategies have consequences for exploration and exploitation of international markets, what is learned and how much is learned, and proactive internationalization strategies for firms. © 2009 Wiley Periodicals, Inc.
How market orientation and outsourcing create capability and impact business performance
Authors: Singh Satyendra
Published: August 2009

For most firms, developing the capability to compete and perform is crucial. The literature suggests that market orientation and outsourcing are two such sources for building capabilities in the marketplace. However, the relative contribution of market orientation and outsourcing to capability and superior business performance is unclear. To bring clarity, two pathways through which market orientation and outsourcing build capability and enhance business performance are proposed. Using data from foreign and Indian firms, the results indicate that both market orientation and outsourcing contribute to building capability, and that outsourcing further contributes to business performance. Also, it was discovered that low‐risk market‐oriented and high‐risk outsourcing firms experienced a positive impact on business performance. The implication of these results for managers is that market orientation and outsourcing can be complementary tools in their efforts to build capability, enhance business performance, and manage risky environmental conditions. © 2009 Wiley Periodicals, Inc.
Chinese tax changes and offshore comparisons
Authors: Lipsher Laurence E.
Published: August 2009

Lipsher delivered the following observations and remarks in Shanghai to a group consisting primarily of Chinese tax professionals. The size and composition of the group marked an achievement that validated the close to two decades that Lipsher has lived in China—especially since January 1, 1994, when the first national tax law came into effect. He was in China here when the first, six‐page tax law went into effect. Simultaneously, on that very same day, a new U.S. tax law came into effect. Only that law was 1,447 pages long! His remarks offer an overview of tax‐law changes in China and the advantages of offshore tax benefits from the perspective of an American who has lived and worked in the Chinese business environment as a tax expert as it has evolved and matured. © 2009 Wiley Periodicals, Inc.
Diagnostic accuracy of transvaginal ultrasound examination for assigning a specific diagnosis to adnexal masses
Authors: Sokalska A. , Timmerman D. , Testa A. C. , Van Holsbeke C. , Lissoni A. A , Leone F. P. G. , Jurkovic D. , Valentin L.
Published: August 2009

Objectives

To determine the sensitivity and specificity of subjective evaluation of gray‐scale and Doppler ultrasound findings (here called pattern recognition) when used by experienced ultrasound examiners with regard to making a specific diagnosis of adnexal masses.

Methods

Within the framework of a European multicenter study, the International Ovarian Tumor Analysis study, comprising nine ultrasound centers, women with at least one adnexal mass were examined with gray‐scale and color Doppler ultrasonography by experienced ultrasound examiners. A standardized examination technique, and standardized terms and definitions were used. Using pattern recognition the examiners classified each mass as benign or malignant and suggested a specific diagnosis (e.g. dermoid cyst or endometrioma). The reference standard was the histology of the surgically removed adnexal tumors.

Results

A total of 1066 women were included, of whom 800 had a benign mass and 266 a malignant mass. A specific diagnosis based on ultrasound findings was suggested in 899 (84%) tumors. The specificity was high for all diagnoses (range, 94–100%). The sensitivity was highest for benign teratoma/dermoid cysts (86%, 100/116), hydrosalpinges (86%, 18/21), peritoneal pseudocysts (80%, 4/5) and endometriomas (77%, 153/199), and lowest for functional cysts (17%, 4/24), paraovarian/parasalpingeal cysts (14%, 3/21), benign rare tumors (11%, 1/9), adenofibromas (8%, 3/39), simple cysts (6%, 1/18) and struma ovarii (0%, 0/5). The positive and negative likelihood ratios of pattern recognition with regard to dermoid cysts, hydrosalpinges and endometriomas were 68.2 and 0.14, 38.9 and 0.15, and 33.3 and 0.24, respectively. Dermoid cysts, hydrosalpinges, functional cysts, paraovarian cysts, peritoneal pseudocysts, fibromas/fibrothecomas and simple cysts were never misdiagnosed as malignancies by the ultrasound examiner, whereas more than 10% of inflammatory processes, adenofibromas and rare benign tumors including struma ovarii were misdiagnosed as malignancies.

Conclusions

Using subjective evaluation of gray‐scale and Doppler ultrasound findings it is possible to make an almost conclusive diagnosis of a dermoid cyst, endometrioma and hydrosalpinx. Many other adnexal pathologies can be recognized but not confidently confirmed or excluded. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Diagnostic performance of routine ultrasound screening for fetal abnormalities in an unselected Swedish population in 2000–2005
Authors: Romosan G. , Henriksson E. , Rylander A. , Valentin L.
Published: August 2009

Objectives

To determine the detection rate of fetal malformations and chromosomal abnormalities and the rate of false‐positive ultrasound diagnoses at routine ultrasound examinations carried out by specially trained midwives in an unselected pregnant population from 2000 to 2005, and to describe the consequences of true‐positive and false‐positive ultrasound diagnoses of fetal malformations.

Methods

A retrospective analysis was undertaken of all babies born in Malmö, Sweden, between January 2000 and December 2005 by mothers residing in Malmö and of all fetuses with an ultrasound diagnosis of malformation made in the same time interval at the two units performing all routine pregnancy scans in Malmö. All women underwent two routine scans, at 18 and 32 weeks, including scrutiny of the fetal anatomy. Detection rates and false‐positive rates were calculated per fetus.

Results

The prevalence of chromosomally abnormal fetuses was 0.31% (52/16 775); that of chromosomally normal fetuses with major and minor malformations was 1.80% (302/16 775) and 1.32% (222/16 775), respectively. The detection rate of fetuses with major malformations but normal chromosomes was 68% (205/302), with a detection rate at < 22 weeks of 37% (112/302). In addition, 46% (24/52) of all chromosomally abnormal fetuses were diagnosed before birth because a malformation was detected at ultrasound imaging, 33% (17/52) being detected at < 22 gestational weeks. In all, 68 pregnancies were terminated because of an ultrasound diagnosis of fetal malformation (0.4% of all pregnancies and 47% of the pregnancies in which a fetal malformation was detected by ultrasound examination before 22 weeks). A false‐positive ultrasound diagnosis of malformation was made in 0.19% (31/16 180) of the normally formed fetuses and in 20 (0.12%) fetuses the abnormal finding persisted during pregnancy. No fetus assigned a false‐positive diagnosis was lost by termination of pregnancy, but most were subjected to one or more unnecessary interventions before birth (e.g. amniocentesis), at birth (e.g. Cesarean section) or after birth (e.g. electrocardiogram, X‐ray, ultrasound examination or treatment with antibiotics).

Conclusions

In a screening program consisting of one fetal anomaly scan at 18 weeks and another at 32 weeks the detection rate of major malformations in chromosomally normal fetuses was 68% with a detection rate of 37% at < 22 weeks. The corresponding detection rates of chromosomally abnormal fetuses were 46% and 33%. Fewer than one in 500 screened fetuses had an ultrasound diagnosis of an anomaly that was not confirmed after birth. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.
Hydrothermal Synthesis of a 3D Polymeric Cobalt(II) Carboxylate Derivative from 1,2,4,5‐Benzenetetracarbonitrile
Authors: Sun Baiwang , Chen Xiaodan , Ang Siau Gek , Li Zhongshu , Jiang Xindong
Published: August 2009

The metal‐organic complexes Co2(terpy)2(btec)·H2O 1 (terpy = 2,2′:6′,2″‐terpyridine, btec = 1,2,4,5‐benzenetetracarboxylate) was synthesized by hydrothermal synthesis method, using 1,2,4,5‐benzenetetracarbonitrile, terpy and CoAc2·4H2O. Single crystal X‐ray diffraction showed that each btec4– ligand links four CoII atoms and each CoII atom links to two btec4– ligands forming a 1D double‐chain structure. Furthermore, the chains pack together through short face–face π–π interactions forming a 3D supramolecular structure. Additionally, the magnetic measurements show antiferromagnetic interactions among metal ions for compound 1.
Observations on the female reproductive cycles of captive Asian yellow pond turtles (Mauremys mutica) with radiography and ultrasonography
Authors: Cheng Yuan‐Yu , Chen Ting‐Yu , Yu Pin‐Huan , Chi Chau‐Hwa
Published: August 2009

The annual reproductive cycle of 27 female Mauremys mutica was observed by radiography and ultrasonography from April 2006 to August 2007. Radiography was used to monitor clutch size and ultrasonography was used to monitor changes in the ovarian follicles. The follicles started to enlarge in September and became preovulatory in January. The mean maximum follicle diameter of ovulation was 18.30±1.44 mm, and ovulation occurred from March through August. Eggs were laid between April and August. Turtles entered latent period in early August and the maximum follicular size was at a low of 13.22±2.36 mm in late September. The vitellogenesis of the next reproductive cycle began in October. The 24 adult females laid 56 clutches containing a total of 227 eggs. Average clutch size was 4.05 eggs (range 1–8) and there were 2.33 clutches (range 1–4) per female. Egg shell images were first observed on the sixth or seventh day after ovulation. The oviductal period averaged 6.9 weeks (range 2–16 weeks) on the first clutch, 3.4 weeks (range 2–8 weeks) on the second, and 2.75 weeks (range 2–6 weeks) for the third. Radiography and ultrasonography are non‐invasive and convenient methods to evaluate the reproductive cycle of female M. mutica. They should be applicable to other turtles and should greatly enhance knowledge of reproductive physiology. Zoo Biol 29:50–58, 2010. © 2009 Wiley‐Liss, Inc.
Photoelectric Properties of Silicon Nanocrystals/P3HT Bulk-Heterojunction Ordered in Titanium Dioxide Nanotube Arrays
Authors: Švrček Vladimir , Turkevych Ivan , Kondo Michio
Published: August 2009

A silicon nanocrystals (Si-ncs) conjugated-polymer-based bulk-heterojunction represents a promising approach for low-cost hybrid solar cells. In this contribution, the bulk-heterojunction is based on Si-ncs prepared by electrochemical etching and poly(3-hexylthiophene) (P3HT) polymer. Photoelectric properties in parallel and vertical device-like configuration were investigated. Electronic interaction between the polymer and surfactant-free Si-ncs is achieved. Temperature-dependent photoluminescence and transport properties were studied and the ratio between the photo- and dark-conductivity of 1.7 was achieved at ambient conditions. Furthermore the porous titanium dioxide (TiO2) nanotubes’ template was used for vertical order of photosensitive Si-ncs/P3HT-based blend. The anodization of titanium foil in ethylene glycol-based electrolyte containing fluoride ions and subsequent thermal annealing were used to prepare anatase TiO2nanotube arrays. The arrays with nanotube inner diameter of 90 and 50 nm were used for vertical ordering of the Si-ncs/P3HT bulk-heterojunction.
Involvement of transient receptor potential vanilloid 1 receptors in protease‐activated receptor‐2‐induced joint inflammation and nociception
Authors: Helyes Zs. , Sándor K. , Borbély É. , Tékus V. , Pintér E. , Elekes K. , Tóth D.M. , Szolcsányi J. , McDougall J.J.
Published: August 2009

Protease‐activated receptor‐2 (PAR‐2) is a G‐protein‐coupled receptor activated through proteolytic cleavage. It is localized on epithelial, endothelial and inflammatory cells, as well as on transient receptor potential vanilloid 1 (TRPV1) receptor‐expressing neurones. It plays an important role in inflammatory/nociceptive processes. Since there are few reports concerning PAR‐2 function in joints, the effects of intraarticular PAR‐2 activation on joint pain and inflammation were studied. Secondary hyperalgesia/allodynia, spontaneous weight distribution, swelling and inflammatory cytokine production were measured and the involvement of TRPV1 ion channels was investigated in rats and mice. Injection of the PAR‐2 receptor agonist SLIGRL‐NH2into the knee decreased touch sensitivity and weight bearing of the ipsilateral hindlimb in both species. Secondary mechanical allodynia/hyperalgesia and impaired weight distribution were significantly reduced by the TRPV1 antagonist SB366791 in rats and by the genetic deletion of this receptor in mice. PAR‐2 activation did not cause significant joint swelling, but increased IL‐1β concentration which was not influenced by the lack of the TRPV1 channel. For comparison, intraplantar SLIGRL‐NH2evoked similar primary mechanical hyperalgesia and impaired weight distribution in both WT and TRPV1 deficient mice, but oedema was smaller in the knockouts. The inactive peptide, LRGILS‐NH2, injected into either site did not induce any inflammatory or nociceptive changes. These data provide evidence for a significant role of TRPV1 receptors in secondary mechanical hyperalgesia/allodynia and spontaneous pain induced by PAR‐2 receptor activation in the knee joint. Although intraplantar PAR‐2 activation‐induced oedema is also TRPV1 receptor‐mediated, primary mechanical hyperalgesia, impaired weight distribution and IL‐1β production are independent of this channel.
Impact of peptidoglycan O‐acetylation on autolytic activities of the Enterococcus faecalis N‐acetylglucosaminidase AtlA and N‐acetylmuramidase AtlB
Authors: Emirian Aurélie , Fromentin Sophie , Eckert Catherine , Chau Françoise , Dubost Lionel , Delepierre Muriel , Gutmann Laurent , Arthur Michel , Mesnage Stéphane
Published: August 2009

Autolysins are potentially lethal enzymes that partially hydrolyze peptidoglycan for incorporation of new precursors and septum cleavage after cell division. Here, we explored the impact of peptidoglycan O‐acetylation on the enzymatic activities of Enterococcus faecalis major autolysins, the N‐acetylglucosaminidase AtlA and the N‐acetylmuramidase AtlB. We constructed isogenic strains with various O‐acetylation levels and used them as substrates to assay E. faecalis autolysin activities. Peptidoglycan O‐acetylation had a marginal inhibitory impact on the activities of these enzymes. In contrast, removal of cell wall glycopolymers increased the AtlB activity (37‐fold), suggesting that these polymers negatively control the activity of this enzyme.