bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Oxygen at the Interface between Titanium and Carbon Nanotubes
Authors: Felten Alexandre , Suarez‐Martinez Irene , Ke Xiaoxing , Van Tendeloo Gustaaf , Ghijsen Jacques , Pireaux Jean‐Jacques , Drube Wolfgang , Bittencourt Carla , Ewels Christopher P.
Published: May 2009

We study the interface between carbon nanotubes (CNTs) and surface‐deposited titanium using electron microscopy and photoemission spectroscopy, supported by density functional calculations. Charge transfer from the Ti atoms to the nanotube and carbide formation is observed at the interface which indicates strong interaction. Nevertheless, the presence of oxygen between the Ti and the CNTs significantly weakens the Ti–CNT interaction. Ti atoms at the surface will preferentially bond to oxygenated sites. Potential sources of oxygen impurities are examined, namely oxygen from any residual atmosphere and pre‐existing oxygen impurities on the nanotube surface, which we enhance through oxygen plasma surface pre‐treatment. Variation in literature data concerning Ohmic contacts between Ti and carbon nanotubes is explained via sample pre‐treatment and differing vacuum levels, and we suggest improved treatment routes for reliable Schottky barrier‐free Ti–nanotube contact formation.
Influence of Iodide Concentration on the Efficiency and Stability of Dye‐Sensitized Solar Cell Containing Non‐Volatile Electrolyte
Authors: Zhang Zhipan , Ito Seigo , Moser Jacques‐E. , Zakeeruddin Shaik M. , Grätzel Michael
Published: May 2009

Dye‐sensitized solar cells based on nanocrystalline TiO2 have been fabricated with an amphiphilic ruthenium sensitizer NaRu(4‐carboxylic acid‐4′‐carboxylate)(4,4′‐dinonyl‐2,2′‐bipyridine)(NCS)2, coded as Z‐907Na, and a series of non‐volatile 3‐methoxyproprionitrile (MPN)‐based electrolytes with different concentration of 1‐methyl‐3‐propylimidazolium iodide (PMII). The short‐circuit photocurrent density increases with increasing iodide concentration until at 1.5 M practically quantitative dye regeneration is achieved as proved by time‐resolved laser experiments. Devices containing 1.0 M PMII electrolyte show excellent stability during long‐time thermal aging at 80 °C and under light soaking at 60 °C.
From Single‐Biomolecule Electrochemistry to Biosensors and Biofuel Cells
Authors: Calvo Ernesto Julio
Published: May 2009

The bioelectrochemistry symposium at the 59th annual meeting of the International Society of Electrochemistry (ISE) covered significant developments in this area—from biomimetics, redox proteins, and enzymes, to biosensors and biofuel‐cell applications. This conference report highlights some of the most important contributions (the picture shows a schematic representation of an amperometric enzyme electrode, courtesy of P.N. Bartlett).

magnified image
Inside Cover: Absorption Spectra of 4‐Nitrophenolate Ions Measured in Vacuo and in Solution (ChemPhysChem 8/2009)
Authors: Suhr Kirketerp Maj‐Britt , Åxman Petersen Michael , Wanko Marius , Andres Espinosa Leal Leonardo , Zettergren Henning , Raymo Françisco M. , Rubio Angel , Brøndsted Nielsen Mogens , Brøndsted Nielsen Steen
Published: May 2009

The inside cover picture shows gas‐phase absorption spectra of four p‐nitrophenolates. The ions cover the entire visible spectrum when isolated in vacuo and are located within a narrower region in solution. On p. 1207 A. Rubio, M. Brøndsted Nielsen, S. Brøndsted Nielsen et al. use the gas‐phase absorption maxima to benchmark excitation energy calculations (blue lines).

magnified image
Differential amplifier with improved gain‐accuracy and linearity
Authors: Wu R. , Lidgey F. J. , Hayatleh K. , Hart B. L.
Published: May 2009

A novel circuit design technique is presented which improves gain‐accuracy and linearity in differential amplifiers. The technique employs negative impedance compensation and results demonstrate a significant performance improvement in precision, lowering sensitivity, and wide dynamic range. A theoretical underpinning is given together with the results of a demonstrator differential input/output amplifier with gain of 12 dB. The simulation results show that, with the novel method, both the gain‐accuracy and linearity can be improved greatly. Especially, the linearity improvement in IMD can get to more than 23 dB with a required gain. Copyright © 2009 John Wiley & Sons, Ltd.
Programmable feedforward linearized CMOS OTA for fully differential continuous‐time filter design
Authors: Szczepanski Stanislaw , Pankiewicz Bogdan , Koziel Slawomir
Published: May 2009

In this paper, a feedforward linearization method for programmable CMOS operational transconductance amplifier (OTA) is described. The proposed circuit technique is developed using simple source‐coupled differential pair transconductors, a feedback‐loop amplifier for self‐adjusting transcoductance (gm) and a linear reference resistor (R). As a result, an efficient linearization of a transfer characteristic of the OTA is obtained. SPICE simulations show that for 0.35µm AMS CMOS process with a single +3V power supply, total harmonic distortion at 1 Vppand temperature range from −30 to +90°C is less than −49.3 dB in comparison with −35.8  dB without linearization. Moreover, the input voltage range of linear operation is increased. Power consumption of the linearized OTA circuit is 0.86 mW. Finally, the OTA is used to design a third‐order elliptic low‐pass filter in high‐frequency range. The cut‐off frequency of the operational transconductance amplifier‐capacitor (OTA‐C) filter is tunable in the range of 322.6 kHz–10 MHz using the feedforward linearized OTAs with the digitally programmable current mirrors. Copyright © 2009 John Wiley & Sons, Ltd.
Ecohydrological controls on snowmelt partitioning in mixed‐conifer sub‐alpine forests
Authors: Molotch Noah P. , Brooks Paul D. , Burns Sean P. , Litvak Marcy , Monson Russell K. , McConnell Joseph R. , Musselman Keith
Published: May 2009

We used co‐located observations of snow depth, soil temperature, and moisture and energy fluxes to monitor variability in snowmelt infiltration and vegetation water use at mixed‐conifer sub‐alpine forest sites in the Valles Caldera, New Mexico (3020 m) and on Niwot Ridge, Colorado (3050 m). At both sites, vegetation structure largely controlled the distribution of snow accumulation with 29% greater accumulation in open versus under‐canopy locations. Snow ablation rates were diminished by 39% in under‐canopy locations, indicating increases in vegetation density act to extend the duration of the snowmelt season. Similarly, differences in climate altered snow‐season duration, snowmelt infiltration and evapotranspiration. Commencement of the growing season was coincident with melt‐water input to the soil and lagged behind springtime increases in air temperature by 12 days on average, ranging from 2 to 33 days under warmer and colder conditions, respectively. Similarly, the timing of peak soil moisture was highly variable, lagging behind springtime increases in air temperature by 42 and 31 days on average at the Colorado and New Mexico sites, respectively. Latent heat flux and associated evaporative loss to the atmosphere was 28% greater for the year with earlier onset of snowmelt infiltration. Given the large and variable fraction of precipitation that was partitioned into water vapour loss, the combined effects of changes in vegetation structure, climate and associated changes to the timing and magnitude of snowmelt may have large effects on the partitioning of snowmelt into evapotranspiration, surface runoff and ground water recharge. Copyright © 2009 John Wiley & Sons, Ltd.
Hydrology and species‐specific effects of Bacopa monnieri and Leersia oryzoides on soil and water chemistry
Authors: Pierce S. C. , Pezeshki S. R. , Larsen D. , Moore M. T.
Published: May 2009

In an 8‐week greenhouse experiment, Bacopa monnieri (water hyssop) and Leersia oryzoides (rice cutgrass) were compared for nutrient assimilation as well as soil and water chemistry under variable flooding regimes using a nutrient solution rich in nitrogen (N) and phosphorus (P). Soil redox potential decreased in flooded treatments; however, mesocosms containing B. monnieri remained aerobic for much of the study, while flooded mesocosms containing L. oryzoides became moderately reduced. Soils containing L. oryzoides were higher in nitrogen. Generally, effluent concentrations of PO43− were higher in B. monnieri mesocosms. B. monnieri immobilization of N and P was significantly less in below‐ground tissues than L. oryzoides. P immobilization in L. oryzoides generally increased in response to flooding, while B. monnieri showed no detectable response. Results indicated that species‐specific flood responses in plant nutrient status are due to differing interactions of B. monnieri and L. oryzoides with the soil environment. Additionally, L. oryzoides demonstrated greater P uptake than B. monnieri across treatments, resulting in decreased concentrations of PO4−3 in effluent. Although N was also affected by flooding and species, generalizations on N allocation within the system are difficult to describe due to the changes in species of N in response to oxidation–reduction gradients and biotic assimilation. Copyright © 2009 John Wiley & Sons, Ltd.
Streamside herbaceous vegetation response to hydrologic restoration on the San Pedro River, Arizona
Authors: Katz Gabrielle L. , Stromberg J. C. , Denslow M. W.
Published: May 2009

Recovery of physical conditions and processes is increasingly emphasized in ecosystem restoration. We examined a restoration project aimed at recovery of groundwater levels and base flows on an undammed desert river. We sampled streamside plant communities and hydrology annually (2003–2008) at six restoration sites at two farms (Three Links Farm and H&E Farm) after groundwater pumping was curtailed for restoration purposes, and at six reference sites. Vascular plant cover was recorded, and species were classified into functional groups based on water needs and life history. Synthetic vegetation metrics and community composition were compared between restoration sites and perennial‐flow reference sites representing target conditions. Perennial sites had higher cover, species richness, relative cover of hydric perennials and hydric annuals, and lower wetland indicator scores than non‐perennial sites, but did not differ in relative cover of non‐native species. Perennial sites had distinct species composition and high species constancy among years. Streamside vegetation was similar at Three Links Farm and perennial reference sites, indicating restoration success; streamside vegetation at H&E Farm differed from target conditions according to most measures. Hydrology is a key factor shaping desert streamside plant communities. However, single river sites may respond differently to hydrologic restoration. Contrasts in site response were likely due to differences in hydrogeomorphic context, exacerbated by drought. Understanding the constraints on restoration response is critical for setting realistic restoration goals and anticipating time frames of ecosystem change. Copyright © 2009 John Wiley & Sons, Ltd.
Preparation of Mesoporous Silica and Carbon Materials with Multilength‐Scale Pores and Hydrogen Sorption Application
Authors: Kwon Tae‐Hwan , Jung Suhyun , Kim Hee‐Jin , Park Seongsoon , Kim Sung‐Jin , Huh Seong
Published: May 2009

A facile method was developed for the preparation of bimodal mesoporous siliceous materials with nanostructured pores in which a cationic organic template, n‐hexadecyltrimethylammonium hydroxide, was employed as a base catalyst as well as a mesopore structure‐directing agent during the slow condensation of tetraethoxysilane. It was possible to alter the pore orientations of smaller pores by adding neutral auxiliary templates such as Brij76 and P123. A series of biomodal mesoporous carbons was also obtained from the bimodal mesoporous silica materials through a nanocasting process. The resulting bimodal mesoporous carbons exhibited decent hydrogen uptake values at 77 K. The maximum hydrogen uptake was 1.33 wt.‐% for the sample having the narrowest pores, while keeping a relatively large pore volume. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Bis(N‐heterocyclic carbene) Dipalladium Complexes: Synthesis, Solid‐State Conformational Studies and Solution Behaviour
Authors: Willans Charlotte E. , Anderson Kirsty M. , Paterson Martin J. , Junk Peter C. , Barbour Leonard J. , Steed Jonathan W.
Published: May 2009

New palladium(II) bis(N‐heterocyclic carbene) (NHC) complexes have been prepared via metallomacrocyclic AgI ligand transfer agents. Reaction of 1,4‐bis(3‐isopropylimidazolium)xylene (1a) hexafluorophosphate with Ag2O gives a AgI macrocyclic NHC complex in which two silver ions are sandwiched between two dipodal ligands (2a). The NHC moieties adopt a cisoid conformation relative to one another. Upon transfer to palladium to give [{PdCl2(MeCN)}2(bis‐NHC)] (3a) the NHC ligands in the complexes adopt a mixture of cisoid and transoid conformers in the solid state, which have been characterized by X‐ray crystallography. In CD3CN solution the cisoid and transoid conformers interconvert and exhibit resonances for a single averaged form.DFT calculations indicate an interconversion barrier of 56 kJ mol–1. In CDCl3 solution two different isomers are observed which have been assigned to isomers of a chloride‐bridged dimer (4a) following dissociation of the acetonitrile ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Difluorenyl[2]borametallocenophanes of Group 4 Metals: Synthesis and Structure
Authors: Braunschweig Holger , Kupfer Thomas , Mies Jan , Oechsner Andreas
Published: May 2009

We report the synthesis of difluorenyl[2]borametallocenophanes of Zr and Hf. The ligand precursor has been synthesized starting from 1,2‐dibromo‐1,2‐bis(dimethylamino)diborane(4) upon reaction with Li[C13H9]. All compounds have been fully characterized by multinuclear NMR spectroscopy and, in addition, selected examples by X‐ray analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Winheim, Germany, 2009)
Effect of O6‐alkylguanine‐DNA alkyltransferase on genotoxicity of epihalohydrins
Authors: Kalapila Aley G. , Loktionova Natalia A. , Pegg Anthony E.
Published: May 2009

The effect of O6‐alkylguanine‐DNA alkyltransferase (AGT) on the toxicity and mutagenicity of epihalohydrins was studied. AGT is a DNA repair protein that protects cells from agents that produce genotoxic O6‐alkylguanine lesions by transferring the alkyl group to an internal cysteine residue (Cys145 in human AGT) in a single‐step. This cysteine acceptor site is highly reactive and epihalohydrins reacted readily with AGT at this site with a halide order of reactivity of Br > Cl > F. AGT expression in bacterial cells caused a very large increase in the mutagenicity and cytotoxicity of epibromohydrin. The mutations were almost all G:C to A:T transitions. Epichlorohydrin also augmented AGT‐mediated mutagenesis but to a lesser extent than epibromohydrin. In vitro experiments showed that AGT was covalently cross‐linked to DNA in the presence of epibromohydrin and that this conjugation occurred predominantly at Cys145, and to a smaller extent at Cys150, a less reactive residue also located within the active site pocket. Two pathways yielding the AGT–DNA adduct were found to occur. The predominant mechanism results in an AGT‐epihalohydrin intermediate, which, facilitated by the DNA binding properties of AGT, then reacts covalently with DNA. The second pathway involves an initial reactive DNA‐epihalohydrin intermediate that subsequently reacts with AGT. Our results show that the paradoxical AGT‐mediated increase in genotoxicity which has previously been shown to occur with dihaloalkanes, butadiene diepoxide and nitrogen mustards, also occurs with epihalohydrins and is likely to contribute to their toxicity and mutagenicity. Environ. Mol. Mutagen., 2009. © 2009 Wiley‐Liss, Inc.
Arsenate and dimethylarsinic acid in drinking water did not affect DNA damage repair in urinary bladder transitional cells or micronuclei in bone marrow
Authors: Wang Amy , Kligerman Andrew D. , Holladay Steven D. , Wolf Douglas C. , Robertson John L.
Published: May 2009

Arsenic is a human skin, lung, and urinary bladder carcinogen, and may act as a cocarcinogen in the skin and urinary bladder. Possible modes of action of arsenic carcinogenesis/cocarcinogenesis include oxidative stress induction and inhibition of DNA damage repair. We investigated the effects of arsenic in drinking water on DNA damage repair in urinary bladder transitional cells and on micronucleus formation in bone marrow. F344 rats were given 100 ppm arsenate [As(V)] or dimethylarsinic acid [DMA(V)] in drinking water for 1 week. The in vivo repair of cyclophosphamide (CP)‐induced DNA damage resulting from a single oral gavage of CP, and the in vitro repair of hydrogen peroxide (H2O2)‐ or formaldehyde‐induced DNA damage, resulting from adding H2O2 or formaldehyde into cell medium, were measured by the Comet assay. DMA(V) effects were not observed on either CP‐induced DNA damage induction or on DNA repair. Neither DMA(V) nor As(V) increased the H2O2‐ or formaldehyde‐induced DNA damage, and neither inhibited the repair of H2O2‐induced DNA damage. Neither DMA(V) nor As(V) increased the micronucleus frequency, nor did they elevate micronucleus frequency resulting from CP treatment above the level observed by the treatment with CP alone. These results suggest that arsenic carcinogenesis/cocarcinogenesis in the urinary bladder may not be via DNA damage repair inhibition. To our knowledge this is the first report of arsenic effects on DNA damage repair in the urinary bladder. Environ. Mol. Mutagen. 2009. Published 2009 by Wiley‐Liss, Inc.
Folate deficiency in human peripheral blood lymphocytes induces chromosome 8 aneuploidy but this effect is not modified by riboflavin
Authors: Ni Juan , Lu Lin , Fenech Michael , Wang Xu
Published: May 2009

Chromosome 8 aneuploidy is a common event in certain cancers but whether folate (F) deficiency induces chromosome 8 aneuploidy is not known. Furthermore the impact of riboflavin (R) deficiency, which may alter activity of a key enzyme in folate metabolism, on these events is unknown. Therefore, the aim of our research was to test the following hypotheses: (a) F deficiency induces chromosome 8 aneuploidy; (b) chromosome 8 aneuploidy is affected by F deficiency to a similar degree as chromosome 17 and (c) R deficiency aggravates the risk of aneuploidy caused by F deficiency. These hypotheses were tested in long‐term cultures of lymphocytes from twenty female healthy volunteers (aged 30–48 years). Lymphocytes were cultured in each of the four possible combinations of low (L) and high (H) F (LF, 20 nmol/L, HF 200 nmol/L, respectively) and L and H R (LR 1 nmol/L, HR 500 nmol/L, respectively) media (LFLR, LFHR, HFLR, HFHR) for 9 days. Chromosomes 8 and 17 aneuploidy was measured in mononucleated (MONO) and cytokinesis‐blocked binucleated (BN) cells using dual‐color fluorescence in situ hybridization (FISH) with fluorescent centromeric probes specific for chromosomes 8 and 17. Culture in LF media (LFLR or LFHR) induced significant and similar increases in frequencies of aneuploidy of chromosomes 8 and 17 (P < 0.001) relative to culture in HF media (HFLR or HFHR). There was no significant effect of R concentration on aneuploidy frequency for either chromosome. We conclude that F deficiency is a possible cause of chromosome 8 aneuploidy. Environ. Mol. Mutagen. 2010. © 2009 Wiley‐Liss, Inc.
Shake table study on an ordinary low‐rise building seismically isolated with SU‐FREIs (stable unbonded‐fiber reinforced elastomeric isolators)
Authors: Toopchi‐Nezhad Hamid , Tait Michael J. , Drysdale Robert G.
Published: May 2009

This paper reports on the investigation of novel fiber reinforced elastomeric isolator (FREI) bearings, which do not have thick end plates, and are used in an unbonded application. Owing to the stable lateral load‐displacement response exhibited by the unbonded FREI bearings, the proposed bearings are referred to as stable unbonded (SU)‐FREIs. A shake table test program was conducted on a two‐story test‐structure having well‐defined elastic response characteristics. Compared with the results for the corresponding fixed base (FB) structure, the peak response values, distribution of lateral response throughout the height of the structure, and response time histories of the tested base isolated (BI) structure indicate that significantly improved response can be achieved. This study clearly indicates that SU‐FREI bearings can provide an effective seismic isolation system. Copyright © 2009 John Wiley & Sons, Ltd.
Sensory characterization of Hunter Valley Semillon using descriptive analysis
Authors: Blackman John , Saliba Anthony
Published: May 2009

Semillon wines from the Hunter Valley region, Australia, were evaluated by sensory descriptive analysis using 15 trained judges. The panel initially identified 37 attributes, but after training, discussion and statistical analyses the list was reduced to 12 different aromas. Additionally the tastes of acidity and sweetness were practised and results obtained. Principal component analysis (PCA) of the sensory data obtained combined with mean intensity ratings enabled the wines to be divided into four groups or ‘styles’. PCA revealed a two‐factor solution explaining 82.5% of the total variance, where bottle age was the most important flavour dimension. Three different styles of young Semillon wine and an aged category were determined, confirming that there is a style with substantial flavour that can sold without the need to bottle age. Copyright © 2009 John Wiley & Sons, Ltd.
Suppression of the unsteady vortex wakes of a circular cylinder pair by a doublet‐like counter‐rotation
Authors: Chan Andre S. , Jameson Antony
Published: May 2009

The present investigation examines the suppression of unsteady, two‐dimensional wake instabilities of a pair of identical circular cylinders, placed side‐by‐side normal to freestream at a low Reynolds number of 150. It is found that when the cylinders are counter‐rotated, unsteady vortex wakes can be completely suppressed. At fast enough rotational speeds, a virtual elliptic body is produced by a closed streamline, strongly resembling a doublet potential flow. Copyright © 2009 John Wiley & Sons, Ltd.
Nickel–Zirconia Anode Degradation and Triple Phase Boundary Quantification from Microstructural Analysis
Authors: Faes A. , Hessler‐Wyser A. , Presvytes D. , Vayenas C. G. , Van herle J.
Published: May 2009

Microstructural evolution of anode supported solid oxide fuel cells (SOFC) during medium‐term stack testing has been characterised by scanning electron microscopy (SEM). Low acceleration voltage SEM imaging is used to separate the three anode phases (nickel, yttria‐stabilised zirconia and porosity). Microstructural quantification is obtained using a software code that yields phase proportion, particle size, particle size distribution and a direct measure of triple phase boundary (TPB) density (μm–2). In addition, an anode degradation model is proposed. The model describes the gradual degradation of the anode due to nickel particle sintering and the concomitant loss of TPB. Fundamental operational and structural parameters of the anode can be used to estimate the TPB length change with time from the degradation rate. The combination of experimental results and modelling allows separating the degradation due to sintering of nickel particles from total stack degradation. Anode degradation occurs principally during the first 500 operating hours. For stack tests carried out over more than 1,000 h, anode degradation was responsible for 18 to 41% of the total degradation depending on initial microstructure.
New Fabrication Technique for Series‐Connected Stack With Micro Tubular SOFCs
Authors: Funahashi Y. , Shimamori T. , Suzuki T. , Fujishiro Y. , Awano M.
Published: May 2009

Solid oxide fuel cell (SOFC) is highly efficient and is a promising candidate for future power systems. Among the many types of SOFCs which have been reported, the micro tubular design offers improved thermal robustness, with the possibility of rapid start‐up/shut‐down. In this study, a new stack structure for anode‐supported micro tubular SOFCs was developed in which porous MgO matrices were used to position the micro tubular cell elements. This arrangement allowed for electrical interconnection of each cell in a series, using a silver paste and a connecting LSCF paste for the anode and the cathode, respectively, in the MgO support structure. With this technique, the bundle size could be easily increased towards the kW class module design.
Trend and persistence of precipitation under climate change scenarios for Kansabati basin, India
Authors: Mishra Ashok K. , Özger Mehmet , Singh Vijay P.
Published: May 2009

With increasing uncertainties associated with climate change, precipitation characteristics pattern are receiving much attention these days. This paper investigated the impact of climate change on precipitation in the Kansabati basin, India. Trend and persistence of projected precipitation based on annual, wet and dry periods were studied using global climate model (GCM) and scenario uncertainty. A downscaling method based on Bayesian neural network was applied to project precipitation generated from six GCMs using two scenarios (A2 and B2). The precipitation values for any of three time periods (dry, wet and annual) do not show significant increasing or decreasing trends during 2001–2050 time period. There is likely an increasing trend in precipitation for annual and wet periods during 2051–2100 based on A2 scenario and a decreasing trend in dry period precipitation based on B2 scenario. Persistence during dry period precipitation among stations varies drastically based on historical data with the highest persistence towards north‐west part of the basin. Copyright © 2009 John Wiley & Sons, Ltd.
Annexin‐A7 protects normal prostate cells and induces distinct patterns of RB‐associated cytotoxicity in androgen‐sensitive and ‐resistant prostate cancer cells
Authors: Torosyan Yelizaveta , Simakova Olga , Naga Shanmugam , Mezhevaya Katerina , Leighton Ximena , Diaz Juan , Huang Wei , Pollard Harvey , Srivastava Meera
Published: May 2009

The tumor suppressor role of annexin‐A7 (ANXA7) was previously demonstrated by cancer susceptibility in Anxa7(+/−)‐mice and by ANXA7 loss in human cancers, especially in hormone‐resistant prostate tumors. To gain mechanistic insights into ANXA7 tumor suppression, we undertook an in vitro study in which we compared wild‐type (WT)‐ANXA7 and dominant‐negative (DN)‐ANXA7 effects to a conventional tumor suppressor p53 in prostate cancer cells with different androgen sensitivity. Unlike p53 (which caused cell growth arrest and apoptosis to a noticeable extent in benign PrEC), WT‐ANXA7 demonstrated profound cytotoxicityin androgen‐sensitive LNCaP as well as in the androgen‐resistant DU145 and PC3 prostate cancer cells, but not in PrEC. In androgen‐sensitive LNCaP, WT‐ANXA7 decreased low‐molecular‐weight (LMW) AR protein forms and maintained higher retinoblastoma 1 (RB1)/phospho‐RB1 ratio. In contrast, DN‐ANXA7 (which lacks phosphatidylserine liposome aggregation properties) increased LMW‐AR forms and hyperphosphorylated RB1 that was consistent with the lack of DN‐ANXA7 cytotoxicity. According to the microarray‐based Ingenuity Pathways Analysis, a major WT‐ANXA7 effect in androgen‐sensitive LNCaP constituted of upregulation of the RB1‐binding transcription factor E2F1 along with its downstream proapoptotic targets such as ASK1 and ASPP2. These results suggested a reversal of the RBdependent repression of the proapoptotic E2F‐mediated transcription. However, DN‐ANXA7 increased RB1/2 (but not E2F1) expression and induced the proliferation‐promoting ERK5, thereby maintaining the RB‐dependent repression of E2F‐mediated apoptosis in LNcaP. On the other hand, in androgen‐resistant cells, WT‐ANXA7 tumor suppressor effects involved PTEN and NFkB pathways. Thus, ANXA7 revived the RB‐associated cell survival control and overcame androgen resistance and dysfunctional status of major tumor suppressors commonly mutated in prostate cancer. Published 2009 UICC.
Expression and functional characterization of NPA motif‐null aquaporin‐1 mutations
Authors: Jiang Yong
Published: May 2009

The asparagine‐proline‐alanine sequences (NPA motifs) in Loops B and E of aquaporin are highly conserved. To investigate the role of two NPA motifs in the structure and function of aquaporin water channels, we generated human aquaporins (AQP)‐1 mutations with NPA1 deletion, NPA2 deletion and NPA1,2 double deletion. Immunoblotting and immunofluorescence analysis indicated that all the three human AQP1 mutants possessed identical protein pattern and similar plasma membrane expression pattern compared to wild‐type AQP1. Plasma membrane osmotic water permeability analysis, measured by YFP‐based fluorescence quenching method and Xenopus oocyte expression assays, demonstrated that NPA1 or NPA2 deletion significantly reduced human AQP1 water permeability nearly 50% compared to wild‐type AQP1, while NPA1,2 double deletion had little effect on human AQP1 water permeability. These results provide evidence that NPA motifs are important for water permeation but not essential for the expression, intracellular processing and the basic structure of human aquaporin 1. © 2009 IUBMB IUBMB Life, 61(6): 651–657, 2009
β‐Ketoacyl‐ACP synthase I/II from Plasmodium falciparum (PfFabB/F)—Is it B or F?
Authors: Sharma Shilpi , Sharma Shailendra Kumar , Surolia Namita , Surolia Avadhesha
Published: May 2009

Condensing enzymes play an important and decisive role in terms of fatty acid composition of any organism. They can be classified as condensing enzymes involved in initiating the cycle and enzymes involved in elongating the initiated fatty acyl chain. In E. coli, two isoforms for the elongation condensing enzymes (FabB and FabF) exists whereas Plasmodium genome contains only one isoform. By in vitro complementation studies in E. coli CY244 cells, we show that PfFabB/F functions like E. coli FabF as the growth of the mutant cells could be rescued only in the presence of oleic acid. But unlike bacterial enzyme, PfFabB/F does not increase the cis‐vaccenic acid content in the mutant cells upon lowering the growth temperature. This study thus highlights the distinct properties of P. falciparum FabF which sets it apart from E. coli and most other enzymes of this family described so far. © 2009 IUBMB IUBMB Life, 61(6): 658–662, 2009
Origins and evolution of ADAR‐mediated RNA editing
Authors: Jin Yongfeng , Zhang Wenjing , Li Qi
Published: May 2009

Adenosine deaminases acting on RNA (ADARs) convert adenosines to inosines in double‐stranded RNA in animals. Identification of more ADAR targets and genome sequences of diverse eukaryotes present an opportunity to elucidate the origin and evolution of ADAR‐mediated RNA editing. Comparative analysis of the adenosine deaminase family indicates that the first ADAR might have evolved from adenosine deaminases acting on tRNAs after the split of protozoa and metazoa. ADAR1 and ADAR2 arose by gene duplications in early metazoan evolution, ∼700 million years ago, while ADAR3 and TENR might originate after Urochordata–Vertebrata divergence. More ADAR or ADAR‐like genes emerged in some animals (e.g., fish). Considering the constrained structure, ADAR targets are proposed to have evolved from transposable elements and repeats, random selection, and fixation, and intermolecular pairs of sense and antisense RNA. In some degree, increased ADAR‐mediated gene regulation should substantially contribute to the emergence and evolution of complex metazoans, particularly the nervous system. © 2009 IUBMB IUBMB Life, 61(6): 572–578, 2009
Structural immunology and crystallography help immunologists see the immune system in action: How T and NK cells touch their ligands
Authors: Chen Yong , Shi Yi , Cheng Hao , An Yun‐Qing , Gao George F.
Published: May 2009

Host immune system is an important and sophisticated system, maintaining the balance of host response to “foreign” antigens and ignorance to the normal‐self. To fulfill this achievement the system manipulates a cell–cell interaction through appropriate interactions between cell‐surface receptors and cell‐surface ligands, or cell‐secreted soluble effector molecules to their ligands/receptors/counter‐receptors on the cell surface, triggering further downstream signaling for response effects. T cells and NK cells are important components of the immune system for defending the infections and malignancies and maintaining the proper response against over‐reaction to the host. Receptors on the surface of T cells and NK cells include a number of important protein molecules, for example, T cell receptor (TCR), co‐receptor CD8 or CD4, co‐stimulator CD28, CTLA4, KIR, CD94/NKG2, LILR (ILT/LIR/CD85), Ly49, and so forth. These receptor molecules interact with their ligands on the target cells, including major histocompatibility complex (MHC) (or human leukocyte antigen, HLA), CD80, CD86, and so forth. Detailed understanding of these receptor–ligand pair interactions is crucial for our full knowledge of the immune system, ultimately for us to manipulate the T cell and NK cell functions. Accumulations of the receptor–ligand complex crystal structures in the recent years have provided us a unique angel to see how the immune cells interacting with their partner cells. In this review, we discussed binding specificity, plasticity, and flexibility of the T cell and NK cell receptor/ligand interaction, fitting the structural data with their functions. Structural immunology indeed helps us see how T and NK cells “touch” their target cells in our immune system. © 2009 IUBMB IUBMB Life, 61(6): 579–590, 2009
Construction of methylation linkage map based on MSAP and SSR markers in Sorghum bicolor (L.)
Authors: Duan Yonghong , Qian Jin , Sun Yi , Yi Zhiben , Yan Min
Published: May 2009

Sorghum [Sorghum bicolor (L.) Moench] is one of the most important crops in the semiarid regions of the world. A methylation genetic linkage map of sorghum was constructed using a F2 population derived from a cross of B2V4 × 1383‐2 based on methylation‐sensitive amplified polymorphism (MSAP) and simple sequence repeats (SSR) markers. The map including 11 linkage groups was constructed with 151 loci covering 483.6 cM, 122 of them were MSAP markers, of which 89 loci were produced from EcoRI/MspI enzyme digestion, and 33 loci were produced from EcoRI/HpaII enzyme digestion. The average and maximal distances between adjacent two individual markers were 3.2 and 22.7 cM, respectively. Twenty‐nine previously mapped SSR markers in sorghum were used as anchors, most of the SSR markers in this map ordered collinearly to the published sorghum genetic map, and the distances of common markers intervals similarly. The mapping results also showed that no methylation marker was found on the chromosome SBI‐08; methylation markers from both EcoRI/MspI and EcoRI/HpaII enzyme digestions were detected on SBI‐02‐a and SBI‐05; methylation markers from only EcoRI/HpaII enzyme digestion were detected on SBI‐02‐b; and methylation markers from only EcoRI/MspI enzyme digestion were detected on the other seven chromosomes. High‐density methylation regions were revealed near Xtxp 296 on SBI‐02‐a, Xtxp 69 on SBI‐03, and Xtxp 160 on SBI‐07. Importantly, MSAP method was first used in the construction of a genetic linkage map. MSAP can be used efficiently to detect DNA methylation polymorphisms, and it is also an efficient technique in constructing genetic linkage map. Furthermore, by finding the methylation sites linking with elite genes, cloning target genes may be facilitated. It is also possible to further study epigenetic phenomena of organisms and explain the mechanism of target gene silencing in genetic transformation by analyzing the regions of high‐density methylation sites. © 2009 IUBMB IUBMB Life, 61(6): 663–669, 2009
Effects of SMYD3 overexpression on transformation, serum dependence, and apoptosis sensitivity in NIH3T3 cells
Authors: Luo Xue‐Gang , Xi Tao , Guo Shu , Liu Zhi‐Peng , Wang Nan , Jiang Yong , Zhang Tong‐Cun
Published: May 2009

The SET and MYND domain‐containing protein 3 (SMYD3) gene was found to encode a novel histone methyltransferase involved in human cancer cells. It could specifically methylate histone H3 at lysine 4 and activate the transcription of a set of downstream genes, including of several oncogenes (e.g., N‐Myc, CrkL, Wnt10b, RIZ, and hTERT) and genes involved in the control of cell cycle (e.g., Cyclin G1 and CDK2) and signal transduction (e.g., STAT1, MAP3K11, and PIK3CB). To determine the effects of SMYD3 overexpression on cell transformation, serum dependence and apoptosis sensitivity, we expressed SMYD3 in NIH3T3 cells, and these cells showed several transformed phenotypes as demonstrated by foci formation and colony growth in soft agar. Besides, these transfectants also showed increased serum dependence and depression of sensitivity to apoptosis induced by dexamethasone. These findings lend further understanding to the role of SMYD3 in the genesis of human cancers and might throw light on the development of novel therapeutic approaches to human cancers. © 2009 IUBMB IUBMB Life, 61(6): 679–684, 2009
Concepts in in vivo siRNA delivery for cancer therapy
Authors: Gondi Christopher S. , Rao Jasti S.
Published: May 2009

In vivo gene silencing using RNAi plays an important role in target validation and is advancing towards the development of RNAi‐based therapeutics. RNAs were thought to have just two broad functions in cells as messenger RNAs (mRNAs) and ribosomal RNAs, but recently the relevance of microRNAs is becoming more clearly understood. mRNA molecules transmit information between DNA and protein and, as such, are vital intermediaries for gene expression. Ribosomal and transfer RNAs have structural, catalytic, and information‐decoding roles in the process of protein synthesis, whereas microRNAs are regulators of gene expression. This review presents the early and intriguing successes of using siRNAs for in vivo gene silencing and its use as a possible cancer therapeutics. J. Cell. Physiol. 220: 285–291, 2009. © 2009 Wiley‐Liss, Inc.
Extracellular matrix controls insulin signaling in mammary epithelial cells through the RhoA/Rok pathway
Authors: Lee Yi‐Ju , Hsu Tsai‐Ching , Du Jyun‐Yi , Valentijn Anthony J. , Wu Tung‐Yi , Cheng Cheng‐Fu , Yang Zhihong , Streuli Charles H.
Published: May 2009

Cellular responses are determined by a number of signaling cues in the local microenvironment, such as growth factors and extracellular matrix (ECM). In cultures of mammary epithelial cells (MECs), functional differentiation requires at least two types of signal, lactogenic hormones (i.e., prolactin, insulin, and hydrocortisone) and the specialized ECM, basement membrane (BM). Our previous work has shown that ECM affects insulin signaling in mammary cells. Cell adhesion to BM promotes insulin‐stimulated tyrosine phosphorylation of insulin receptor substrate‐1 (IRS‐1) and association of PI3K with IRS‐1, whereas cells cultured on stromal ECM are inefficient in transducing these post‐receptor events. Here we examine the mechanisms underlying ECM control of IRS phosphorylation. Compared to cells cultured on BM, cells on plastic exhibit higher level of RhoA activity. The amount and the activity of Rho kinase (Rok) associated with IRS‐1 are greater in these cells, leading to serine phosphorylation of IRS‐1. Expression of dominant negative RhoA and the application of Rok inhibitor Y27632 in cells cultured on plastic augment tyrosine phosphorylation of IRS‐1. Conversely, expression of constitutively active RhoA in cells cultured on BM impedes insulin signaling. These data indicate that RhoA/Rok is involved in substratum‐mediated regulation of insulin signaling in MECs, and under the conditions where proper adhesion to BM is missing, such as after wounding and during mammary gland involution, insulin‐mediated cellular differentiation and survival would be defective. J. Cell. Physiol. 220: 476–484, 2009. © 2009 Wiley‐Liss, Inc.
Magic spot: (p) ppGpp
Authors: Wu Jun , Xie Jianping
Published: May 2009

Guanosine 5′‐(tri)diphosphate, 3′‐diphosphate [(p) ppGpp] is a small nucleic acid that helps bacteria survive in limited environments. Gene chip shows that (p) ppGpp is a global transcription‐regulator of genes related to important bacterial metabolic processes. Therefore, more attention should be focused on the molecular mechanisms of (p) ppGpp, as it is the foundation to understanding how bacteria adapt to extreme circumstances through the stringent response. J. Cell. Physiol. 220: 297–302, 2009. © 2009 Wiley‐Liss, Inc.
Essential involvement of cross‐talk between IFN‐γ and TNF‐α in CXCL10 production in human THP‐1 monocytes
Authors: Qi Xu‐Feng , Kim Dong‐Heui , Yoon Yang‐Suk , Jin Dan , Huang Xue‐Zhu , Li Jian‐Hong , Deung Young‐Kun , Lee Kyu‐Jae
Published: May 2009

Interferon (IFN)‐γ‐induced protein 10 (IP‐10/CXCL10), a CXC chemokine, has been documented in several inflammatory and autoimmune disorders including atopic dermatitis and bronchial asthma. Although CXCL10 could be induced by IFN‐γ depending on cell type, the mechanisms regulating CXCL10 production following treatment with combination of IFN‐γ and TNF‐α have not been adequately elucidated in human monocytes. In this study, we showed that TNF‐α had more potential than IFN‐γ to induce CXCL10 production in THP‐1 monocytes. Furthermore, IFN‐γ synergistically enhanced the production of CXCL10 in parallel with the activation of NF‐κB in TNF‐α‐stimulated THP‐1 cells. Blockage of STAT1 or NF‐κB suppressed CXCL10 production. JAKs inhibitors suppressed IFN‐γ plus TNF‐α‐induced production of CXCL10 in parallel with activation of STAT1 and NF‐κB, while ERK inhibitor suppressed production of CXCL10 as well as activation of NF‐κB, but not that of STAT1. IFN‐γ‐induced phosphorylation of JAK1 and JAK2, whereas TNF‐α induced phosphorylation of ERK1/2. Interestingly, IFN‐γ alone had no effect on phosphorylation and degradation of IκB‐α, whereas it significantly promoted TNF‐α‐induced phosphorylation and degradation of IκB‐α. These results suggest that TNF‐α induces CXCL10 production by activating NF‐κB through ERK and that IFN‐γ induces CXCL10 production by increasing the activation of STAT1 through JAKs pathways. Of note, TNF‐α‐induced NF‐κB may be the primary pathway contributing to CXCL10 production in THP‐1 cells. IFN‐γ potentiates TNF‐α‐induced CXCL10 production in THP‐1 cells by increasing the activation of STAT1 and NF‐κB through JAK1 and JAK2. J. Cell. Physiol. 220: 690–697, 2009. © 2009 Wiley‐Liss, Inc.
ToF‐SWI: Simultaneous time of flight and fully flow compensated susceptibility weighted imaging
Authors: Deistung Andreas , Dittrich Enrico , Sedlacik Jan , Rauscher Alexander , Reichenbach Jürgen R.
Published: May 2009

Purpose

To perform systematic investigations on parameter selection of a dual‐echo sequence (ToF‐SWI) for combined 3D time‐of‐flight (ToF) angiography and susceptibility weighted imaging (SWI).

Materials and Methods

ToF‐SWI was implemented on 1.5 T and 3 T MR scanners with complete 3D first‐order flow compensation of the second echo. The efficiency of flow compensating the SWI echo was studied based on phantom and in vivo examinations. Arterial and venous contrasts were examined in volunteers as a function of flip angle and compared with additionally acquired single‐echo ToF and single‐echo SWI data.

Results

Complete flow compensation is required to reduce arterial contamination in the SWI part caused by signal voids. A ramped flip angle of 20° depicted arteries best while venous contrast was preserved. Comparing ToF‐SWI with single‐echo ToF demonstrated arteries with similar quality and delineated all major arteries equally well. Venous delineation was degraded due to lower SNR associated with the thinner slabs used with ToF‐SWI compared to single‐echo SWI acquisition.

Conclusion

A dual‐echo sequence (ToF‐SWI) with full flow compensation of the second echo in a single scan is feasible. This sequence allows simultaneous visualization of intrinsically coregistered arteries and veins without spatial mis‐registration of vessels caused by oblique flow and with minimal signal loss in arteries. J. Magn. Reson. Imaging 2009;29:1478–1484. © 2009 Wiley‐Liss, Inc.
Quantification of hepatic steatosis with MRI: The effects of accurate fat spectral modeling
Authors: Reeder Scott B. , Robson Philip M. , Yu Huanzhou , Shimakawa Ann , Hines Catherine DG , McKenzie Charles A. , Brittain Jean H.
Published: May 2009

Purpose

To develop a chemical‐shift–based imaging method for fat quantification that accounts for the complex spectrum of fat, and to compare this method with MR spectroscopy (MRS). Quantitative noninvasive biomarkers of hepatic steatosis are urgently needed for the diagnosis and management of nonalcoholic fatty liver disease (NAFLD).

Materials and Methods

Hepatic steatosis was measured with “fat‐fraction” images in 31 patients using a multiecho chemical‐shift–based water‐fat separation method at 1.5T. Fat‐fraction images were reconstructed using a conventional signal model that considers fat as a single peak at –210 Hz relative to water (“single peak” reconstruction). Fat‐fraction images were also reconstructed from the same source images using two methods that account for the complex spectrum of fat; precalibrated and self‐calibrated “multipeak” reconstruction. Single‐voxel MRS that was coregistered with imaging was performed for comparison.

Results

Imaging and MRS demonstrated excellent correlation with single peak reconstruction (r2= 0.91), precalibrated multipeak reconstruction (r2= 0.94), and self‐calibrated multipeak reconstruction (r2= 0.91). However, precalibrated multipeak reconstruction demonstrated the best agreement with MRS, with a slope statistically equivalent to 1 (0.96 ± 0.04;P= 0.4), compared to self‐calibrated multipeak reconstruction (0.83 ± 0.05,P= 0.001) and single‐peak reconstruction (0.67 ± 0.04,P< 0.001).

Conclusion

Accurate spectral modeling is necessary for accurate quantification of hepatic steatosis with MRI. J. Magn. Reson. Imaging 2009;29:1332–1339. © 2009 Wiley‐Liss, Inc.
Evolution of hyperacute stroke over 6 hours using serial MR perfusion and diffusion maps
Authors: Harris Ashley D. , Kosior Robert K. , Chen Henry S. , Andersen Linda B. , Frayne Richard
Published: May 2009

Purpose

To develop an appropriate method to evaluate the time‐course of diffusion and perfusion changes in a clinically relevant animal model of ischemic stroke and to examine lesion progression on MR images. An exploration of acute stroke infarct expansion was performed in this study by using a new methodology for developing time‐to‐infarct maps based on the time at which each voxel becomes infarcted. This enabled definition of homogeneous regions from the heterogeneous stroke infarct.

Materials and Methods

Time‐to‐infarct maps were developed based on apparent diffusion coefficient (ADC) changes. These maps were validated and then applied to blood flow and time‐to‐peak maps to examine perfusion changes.

Results

ADC stroke infarct showed different evolution patterns depending on the time at which that region of tissue infarcted. Applying the time‐to‐infarct maps to the perfusion maps showed localized perfusion evolution characteristics. In some regions, perfusion was immediately affected and showed little change over the experiment; however, in some regions perfusion changes were more dynamic.

Conclusion

Results were consistent with the diffusion‐perfusion mismatch hypothesis. In addition, characteristics of collateral recruitment were identified, which has interesting stroke pathophysiology and treatment implications. J. Magn. Reson. Imaging 2009;29:1262–1270. © 2009 Wiley‐Liss, Inc.