bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal responsiveness and maternal selectivity in domestic sheep and goats: The two facets of maternal attachment
Authors: Poindron Pascal , Lévy Frédéric , Keller Matthieu
Published: December 2006

Sheep and goats rapidly establish an exclusive relationship with their neonate following contact with it during a sensitive period of maternal responsiveness induced by the physiological events occurring at parturition. The data concerning the sensory, physiological, and neurobiological factors involved in the activation of both maternal responsiveness and the establishment of selective nursing indicates that these processes are activated simultaneously by the combined action of two main factors, the prepartum rise in circulating estrogen and the vaginocervical stimulation (VCS) caused by fetus expulsion. On the one hand, these two factors act on a neural network including the main olfactory system (MOB), the medial preoptic area (MPOA), and the paraventricular nucleus of the hypothalamus (PVN) to induce maternal responsiveness towards any neonate. The intracerebral release of oxytocin (OT) from the PVN, and the triggering of olfactory attraction for amniotic fluid (AF) are key elements in this process. On the other hand, VCS at birth also sets the MOB ready to memorize the individual odor of the neonate, through the release of peptides and neurotransmitters (noradrenaline and acetylcholine). In addition to the MOB, the network involved in recognition mainly includes the medial and cortical amygdala. Across consolidation processes, reorganization occurs in the network engaged in lamb recognition. Whether this memorization may be potentiated by other sensory cues is not known. The identification of the chemosensory compounds involved in the attraction for AF and in the recognition of the neonate is important for understanding the mechanisms of maternal attachment. © 2006 Wiley Periodicals, Inc. Dev Psychobiol 49: 54–70, 2007
Motivational systems and the neural circuitry of maternal behavior in the rat
Authors: Numan Michael
Published: December 2006

Jay Rosenblatt's approach‐avoidance model of maternal behavior proposes that maternal behavior occurs when the tendency to approach infant stimuli is greater than the tendency to avoid such stimuli. Our research program has uncovered neural circuits which conform to such a model. We present evidence that the medial preoptic area (MPOA: located in the rostral hypothalamus) may regulate maternal responsiveness by depressing antagonistic neural systems which promote withdrawal responses while also activating appetitive neural systems which increase the attractiveness of infant‐related stimuli. These MPOA circuits are activated by the hormonal events of late pregnancy. Preoptic efferents may suppress a central aversion system which includes an amygdala to anterior hypothalamic circuit. Preoptic efferents are also shown to interact with components of the mesolimbic dopamine (DA) system to regulate proactive voluntary maternal responses. We make a distinction between specific (MPOA neurons) and nonspecific motivational systems (mesolimbic DA system) in the regulation of maternal responsiveness. © 2006 Wiley Periodicals, Inc. Dev Psychobiol 49: 12–21, 2007.
Enhanced intra‐switch region recombination during immunoglobulin class switch recombination in 53BP1–/– B cells
Authors: Reina‐San‐Martin Bernardo , Chen Junjie , Nussenzweig André , Nussenzweig Michel C.
Published: December 2006

Immunoglobulin class switch recombination (CSR) is initiated by activation‐induced cytidine deaminase (AID), an enzyme that deaminates cytidine residues in single‐stranded DNA. U:G mismatches created by AID are processed to produce lesions that recruit and activate DNA damage response proteins including Ataxia‐telangiectasia mutated (ATM), histone H2AX, Nijmegen breakage syndrome 1 (Nbs1), and p53 binding protein 1 (53BP1). Among these proteins, absence of 53BP1 produces the most severe impairment of class switching. Here, we demonstrate that AID is targeted normally to switch region DNA and that intra‐switch region recombination is enhanced in 53BP1–/– B cells. In addition, Sµ‐Sγ1 switch region junctions cloned from 53BP1–/– B cells show unusual insertions suggestive of failed class switching. Our data are consistent with a role for 53BP1 in stabilizing the synapsis of switch regions during CSR.
A Surprising Reaction of Trimethylphosphane with the Unsaturated Diruthenium Complex [(η6‐C6Me6)2Ru2(μ2‐H)3]+: Synthesis and Molecular Structure of the Cations [(η6‐C6Me6)Ru2(PMe3)3(μ2‐H)3]+ and [(η6‐C6Me6)2Ru2(PMe3)2(μ2‐H)(H)2]+
Authors: Tschan Mathieu J.‐L. , Chérioux Frédéric , Therrien Bruno , Süss‐Fink Georg
Published: December 2006

Whereas aromatic or aliphatic phosphanes undergo cleavage of the P–C bond in the reaction with [(η6‐C6Me6)2Ru2(μ2‐H)3]+ to give phosphido‐bridged diruthenium cations of the type [(η6‐C6Me6)2Ru2(μ2‐PR2)(μ2‐H)2]+, trimethylphosphane surprisingly yields the substitution product [(η6‐C6Me6)Ru2(PMe3)3(μ2‐H)3]+ (1), as well as the racemic intermediate [(η6‐C6Me6)2Ru2(PMe3)2(μ2‐H)(H)2]+ (2), in the form of the tetrafluoroborate salts. In complex 2, the hydrido ligands are fluxional in solution, as shown by variable‐temperature 1H NMR spectroscopy. Cation 1 reacts with p‐bromothiophenol to give the complex [(η6‐C6Me6)2Ru2(PMe3)3{μ2‐(p‐Br‐C6H4)‐S}(μ2‐H)2]+ (3), isolated as the tetrafluoroborate salt.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Aromatic Thioesters as Protecting Groups for Thiols Against 1,2‐Didehydrobenzenes
Authors: Fowelin Christian , Schüpbach Björn , Terfort Andreas
Published: December 2006

Divalent sulfur compounds usually react with 1,2‐didehydrobenzenes to give a palette of unspecific products. To identify a suitable protecting group for thiols under the reaction conditions typically used for the synthesis of triptycenes, that is, 1,2‐didehydrobenzene generated in situ from 2‐diazoniobenzenecarboxylate at elevated temperatures, a wide‐ranging optimization study was conducted. Of several acyl groups investigated, the benzoyl group turned out to be optimal. The efficiency of this protecting group was demonstrated by the successful transformation of an electron‐poor (thus unreactive) anthracene derivative to the corresponding triptycenethiol derivative. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Glycosylation under Thermodynamic Control: Synthesis of the Di‐ and the Hexasaccharide Fragments of the O‐SP of Vibrio Cholerae O:1 Serotype Ogawa from Fully Functionalized Building Blocks
Authors: Adamo Roberto , Kováč Pavol
Published: December 2006

The known 5‐(methoxycarbonyl)pentyl α‐glycoside of the hexasaccharide of the O‐SP of Vibrio cholerae O:1, serotype Ogawa 31 was newly prepared from side‐chain‐equipped disaccharide building blocks. The intermediate tetrasaccharide 25 was prepared from the disaccharide glycosyl acceptor 11 and the (1→2)‐linked disaccharide thioglycoside glycosyl donor 8, having a (non‐participating) saccharide moiety at C‐2 in the downstream end. When performed conventionally (at room or at sub 0 C temperatures), glycosylations with 11, carried out without anchimeric assistance, showed poor stereoselectivity but the formation of the 1,2‐trans‐glycosidic linkage could be markedly improved through thermodynamic control. This synthetic strategy towards 31 was more efficient than the step‐wise approach, which was based on iterative glycosylation of 11 with 5 followed by delevulinoylation. Thermodynamic control improved considerably the yields of glycosylation of tetrasaccharide glycosyl acceptor 26 with disaccharide donor 18, to give the fully protected hexasaccharide 28, and also a similar reaction of the thioglycoside 18 with methyl 5‐hydroxyhexanoate, to afford the linker‐equipped disaccharide 19. Sequential deacetylation and debenzylation of the hexasaccharide 28, and deprotection of one of its intermediates, 19, gave the target hexasaccharide 31, and the wanted disaccharide 22, respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Independent consulting and the American Evaluation Association: Twenty years later
Authors: Bonnet Deborah G.
Published: December 2006

In this retrospective commentary, the author traces the history of AEA 's Independent Consulting Topical Interest Group and uses her own consulting practice as a case of how independent evaluation consulting has evolved since 1982.
Independent consulting topical interest group: 2004 industry survey
Authors: Jarosewich Tania , Essenmacher Victoria L. , Lynch Christina Olenik , Williams Jennifer E. , Doino‐Ingersoll Jo Ann
Published: December 2006

This chapter summarizes the results of the 2004 Independent Consulting Topical Interest Group Industry Survey. Respondents provided information on demographic characteristics, consulting experience, services, methods, business structures, and income.
Building your evaluation business into a valuable asset
Authors: Hwalek Melanie , Barber Gregory J.
Published: December 2006

This chapter discusses issues related to succession planning and the valuation and sale of service businesses, with a focus on selling an evaluation business.
Developing new lines of business: A case study
Authors: Clegg Judith , Smart Dawn Hanson
Published: December 2006

This chapter's case highlights the benefits new lines of business can provide for independent consulting firms and discusses the issues to consider and caveats.
Evaluation learning circles: A sole proprietor's evaluation capacity‐building strategy
Authors: Cohen Carolyn
Published: December 2006

This chapter's case describes an innovative and replicable evaluation capacity‐building strategy that benefited both the evaluation client and the independent consultant.
Evaluating the evaluator: Development, field testing, and implications of a client‐based method for assessing evaluator performance
Authors: Dowell Kathleen , Haley Jean , Doino‐Ingersoll Jo Ann
Published: December 2006

Systematically assessing the performance of evaluation professionals allows evaluators to “walk the talk.” Using this client‐based evaluation method can be a valuable process for informing practice.
Stability and approximability of the 𝒫1–𝒫0 element for Stokes equations
Authors: Qin Jinshui , Zhang Shangyou
Published: December 2006

In this paper we study the stability and approximability of the 𝒫1–𝒫0 element (continuous piecewise linear for the velocity and piecewise constant for the pressure on triangles) for Stokes equations. Although this element is unstable for all meshes, it provides optimal approximations for the velocity and the pressure in many cases. We establish a relation between the stabilities of the 𝒬1–𝒫0 element (bilinear/constant on quadrilaterals) and the 𝒫1–𝒫0 element. We apply many stability results on the 𝒬1–𝒫0 element to the analysis of the 𝒫1–𝒫0 element. We prove that the element has the optimal order of approximations for the velocity and the pressure on a variety of mesh families.

As a byproduct, we also obtain a basis of divergence‐free piecewise linear functions on a mesh family on squares. Numerical tests are provided to support the theory and to show the efficiency of the newly discovered, truly divergence‐free, 𝒫1 finite element spaces in computation. Copyright © 2006 John Wiley & Sons, Ltd.
The development of a Cartesian cut cell method for incompressible viscous flows
Authors: Gao Feng , Ingram D. M. , Causon D. M. , Mingham C. G.
Published: December 2006

This paper describes the extension of the Cartesian cut cell method to applications involving unsteady incompressible viscous fluid flow. The underlying scheme is based on the solution of the full Navier–Stokes equations for a variable density fluid system using the artificial compressibility technique together with a Jameson‐type dual time iteration. The computational domain encompasses two fluid regions and the interface between them is treated as a contact discontinuity in the density field, thereby eliminating the need for special free surface tracking procedures. The Cartesian cut cell technique is used for fitting the complex geometry of solid boundaries across a stationary background Cartesian grid which is located inside the computational domain. A time accurate solution is achieved by using an implicit dual‐time iteration technique based on a slope‐limited, high‐order, Godunov‐type scheme for the inviscid fluxes, while the viscous fluxes are estimated using central differencing. Validation of the new technique is by modelling the unsteady Couette flow and the Rayleigh–Taylor instability problems. Finally, a test case for wave run‐up and overtopping over an impermeable sea dike is performed. Copyright © 2006 John Wiley & Sons, Ltd.
Insulin‐like growth factor type 1 receptor signaling in the cells of oligodendrocyte lineage is required for normal in vivo oligodendrocyte development and myelination
Authors: Zeger Martha , Popken Greg , Zhang Jihui , Xuan Shouhong , Lu Q. Richard , Schwab Markus H. , Nave Klaus‐Armin , Rowitch David , D'Ercole A. Joseph , Ye Ping
Published: December 2006

Insulin‐like growth factor‐I (IGF‐I) has been shown to be a potent agent in promoting the growth and differentiation of oligodendrocyte precursors, and in stimulating myelination during development and following injury. To definitively determine whether IGF‐I acts directly on the cells of oligodendrocyte lineage, we generated lines of mice in which the type 1 IGF receptor gene (igf1r) was conditionally ablated either in Olig1 or proteolipid protein expressing cells (termed IGF1Rpre‐oligo‐ko and IGF1Roligo‐ko mice, respectively). Compared with wild type mice, IGF1Rpre‐oligo‐ko mice had a decreased volume (by 35–55%) and cell number (by 54–70%) in the corpus callosum (CC) and anterior commissure at 2 and 6 weeks of age, respectively. IGF1Roligo‐ko mice by 25 weeks of age also showed reductions, albeit less marked, in CC volume and cell number. Unlike astrocytes, the percentage of NG2+ oligodendrocyte precursors was decreased by ∼13% in 2‐week‐old IGF1Rpre‐oligo‐ko mice, while the percentage of CC1+ mature oligodendrocytes was decreased by ∼24% in 6‐week‐old IGF1Rpre‐oligo‐ko mice and ∼25% in 25‐week‐old IGF1Roligo‐ko mice. The reduction in these cells is apparently a result of decreased proliferation and increased apoptosis. These results indicate that IGF‐I directly affects oligodendrocytes and myelination in vivo via IGF1R, and that IGF1R signaling in the cells of oligodendrocyte lineage is required for normal oligodendrocyte development and myelination. These data also provide a fundamental basis for developing strategies with the potential to target IGF‐IGF1R signaling pathways in oligodendrocyte lineage cells for the treatment of demyelinating disorders. © 2006 Wiley‐Liss, Inc.
Heat transport in the Red Lake Bog, Glacial Lake Agassiz Peatlands
Authors: McKenzie Jeffrey M. , Siegel Donald I. , Rosenberry Donald O. , Glaser Paul H. , Voss Clifford I.
Published: December 2006

We report the results of an investigation on the processes controlling heat transport in peat under a large bog in the Glacial Lake Agassiz Peatlands. For 2 years, starting in July 1998, we recorded temperature at 12 depth intervals from 0 to 400 cm within a vertical peat profile at the crest of the bog at sub‐daily intervals. We also recorded air temperature 1 m above the peat surface. We calculate a peat thermal conductivity of 0·5 W m−1 °C−1 and model vertical heat transport through the peat using the SUTRA model. The model was calibrated to the first year of data, and then evaluated against the second year of collected heat data. The model results suggest that advective pore‐water flow is not necessary to transport heat within the peat profile and most of the heat is transferred by thermal conduction alone in these waterlogged soils. In the spring season, a zero‐curtain effect controls the transport of heat through shallow depths of the peat. Changes in local climate and the resulting changes in thermal transport still may cause non‐linear feedbacks in methane emissions related to the generation of methane deeper within the peat profile as regional temperatures increase. Copyright © 2006 John Wiley & Sons, Ltd.
Experimental study on lag time for a small watershed
Authors: Zhang Shifeng , Liu Changming , Yao Zhijun , Guo Lei
Published: December 2006

This paper is focused on the lag time of flow confluence. Lag is described empirically by the precipitation factor in hydrological modelling, but the traditional way to establish the relationship between lag and intensity is not very satisfactory in arid and semi‐arid regions. A total 215 rainfall–runoff experiments were conducted to reveal the effects of net rain duration on lag and intensity. The results show that a correlation between lag and rain intensity exists under certain conditions. There is a critical value in net rain intensity (0·8–1 mm min−1) in the correlation curve of lag and net rain intensity in the given experimental watershed in the laboratory. Similarly, a critical value of net rain duration also exists. This value is the total confluence time. The features of lag time change significantly if intensity or duration is less or greater than the critical value. The study also explores the joint effects of net rain intensity and duration on lag. The formula established among lag, intensity and duration resulted in a better fit. Therefore, the two‐parameter (intensity and duration) empirical formula for lag is better than the traditional single‐parameter (intensity) method. This two‐parameter correlation formula can also be applied to a temporally and spatially uneven runoff processes. A typical field watershed is selected to test the results of the experiments. Copyright © 2006 John Wiley & Sons, Ltd.
Influence of groundwater pumping on streamflow restoration following upstream dam removal
Authors: Constantz Jim , Essaid Hedeff
Published: December 2006

We compared streamflow in basins under the combined impacts of an upland dam and groundwater pumping withdrawals, by examining streamflow in the presence and absence of each impact. As a qualitative analysis, inter‐watershed streamflow comparisons were performed for several rivers flowing into the east side of the Central Valley, CA. Results suggest that, in the absence of upland dams supporting large reservoirs, some reaches of these rivers might develop ephemeral streamflow in late summer. As a quantitative analysis, we conducted a series of streamflow/groundwater simulations (using MODFLOW‐2000 plus the streamflow routing package, SFR1) for a representative hypothetical watershed, with an upland dam and groundwater pumping in the downstream basin, under humid, semi‐arid, and arid conditions. As a result of including the impact of groundwater pumping, post‐dam removal simulated streamflow was significantly less than natural streamflow. The model predicts extensive ephemeral conditions in the basin during September for both the arid and semi‐arid cases. The model predicts continued perennial conditions in the humid case, but spatially weighted, average streamflow of only 71% of natural September streamflow, as a result of continued pumping after dam removal. Published in 2006 by John Wiley & Sons, Ltd.
The dynamic relationship between the euro overnight rate, the ECB's policy rate and the term spread
Authors: Nautz Dieter , Offermanns Christian J.
Published: December 2006

This paper investigates how the dynamic adjustment of the European overnight rate Eonia to the term spread and the European Central Bank's (ECB's) policy rate is affected by rate expectations and the operational framework of the ECB. In line with recent evidence found for the US and Japan, the reaction of the Eonia to the term spread is non‐symmetric. Moreover, the response of the Eonia to the policy rate depends on both, the repo auction format and the position of the Eonia in the ECB's interest rate corridor. Copyright © 2006 John Wiley & Sons, Ltd.
Ab initio quantum mechanics‐based free energy perturbation method for calculating relative solvation free energies
Authors: Reddy M. Rami , Singh U. C. , Erion Mark D.
Published: December 2006

A free energy perturbation (FEP) method was developed that uses ab initio quantum mechanics (QM) for treating the solute molecules and molecular mechanics (MM) for treating the surroundings. Like our earlier results using AM1 semi empirical QMs, the ab initio QM/MM‐based FEP method was shown to accurately calculate relative solvation free energies for a diverse set of small molecules that differ significantly in structure, aromaticity, hydrogen bonding potential, and electron density. Accuracy was similar to or better than conventional FEP methods. The QM/MM‐based methods eliminate the need for time‐consuming development of MM force field parameters, which are frequently required for drug‐like molecules containing structural motifs not adequately described by MM. Future automation of the method and parallelization of the code for Linux 128/256/512 clusters is expected to enhance the speed and increase its use for drug design and lead optimization. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 491–494, 2007
On the quality of the hardness kernel and the Fukui function to evaluate the global hardness
Authors: Torrent‐Sucarrat Miquel , Salvador Pedro , Geerlings Paul , Solà Miquel
Published: December 2006

An approximated hardness kernel, which includes the second derivative with respect to the density of the kinetic energy, the electron–electron coulomb repulsion, and the exchange density functionals, has been tested for the calculation of the global hardness. The results obtained for a series of 40 cations and neutral systems and 16 anions represent in most cases an improvement of the results obtained using the HOMO‐LUMO gap approach and indicate the viability of this approach to evaluate global hardness. In addition, the relevance of the Fukui function approximation and the role of the three components of the hardness kernel in the evaluation of the global hardness have been analyzed. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 574–583, 2007
A theoretical study of fullerene–ferrocene hybrids
Authors: Kang Hong Seok
Published: December 2006

Using density functional theory within the generalized gradient approximation, I analyzed the electronic structure of a C60–ferrocene hybrid [= C FeCp] around HOMO in comparison with that of ferrocene, where C and Cp denote C60(CH3)5 and a cyclopentadienyl ring. HOMO–LUMO gap is significantly smaller than that of ferrocene because of the intervention of π(C) states below LUMO. In addition, geometrical and electronic structures of N@C FeCp are also investigated. I find that there are two isomers with the energy difference of 0.13 eV. In one of the two, the encased nitrogen atom is located at the center of the fullerene cage. The Fe atom is η5‐coordinated to both Cp and R*, where R* is a five‐membered ring of C cage. On the other hand, the atom is coordinated to R* with η4‐hapticity, and the nitrogen atom is bonded to a carbon atom of the R* ring in the other isomer. Upon the isomerization between the two isomers, there occurs a partial transfer of spin density between the nitrogen and Fe atoms as well as the creation and breaking of a CN bond. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 594–600, 2007
Comparison of basis set effects and the performance of ab initio and DFT methods for probing equilibrium fluctuations
Authors: Walker Ross C. , Mercer Ian P. , Gould Ian R. , Klug David R.
Published: December 2006

The electronic absorption and emission spectra of large molecules reflect the extent and timescale of electron‐vibration coupling and therefore the extent and timescale of relaxation/reorganization in response to a perturbation. In this paper, we present a comparison of the calculated absorption and emission spectra of NADH in liver alcohol dehydrogenase (LADH), using quantum mechanical/molecular mechanical methods, in which we vary the QM component. Specifically, we have looked at the influence of basis set (STO‐3G, 3‐21G*, 6‐31G*, CC‐pVDZ, and 6‐311G**), as well as the influence of applying the DFT TD‐B3LYP and ab initio TD‐HF and CIS methods to the calculation of absorption/emission spectra and the reorganization energy (Stokes shift). The ab initio TD‐HF and CIS methods reproduce the experimentally determined Stokes shift and spectral profiles to a high level of agreement, while the TD‐B3LYP method significantly underestimates the Stokes shift, by 45%. We comment on the origin of this problem and suggest that ab initio methods may be naturally more suited to predicting molecular behavior away from equilibrium geometries. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 478–490, 2007
Elucidating the mechanism for the reduction of nitrite by copper nitrite reductase—A contribution from quantum chemical studies
Authors: De Marothy S. A. , Blomberg M. R. A. , Siegbahn P. E. M.
Published: December 2006

Density functional methods have been applied to investigate the properties of the active site of copper‐containing nitrite reductases and possible reaction mechanisms for the enzyme catalysis. The results for a model of the active site indicate that a hydroxyl intermediate is not formed during the catalytic cycle, but rather a state with a protonated nitrite bound to the reduced copper. Electron affinity calculations indicate that reduction of the T2 copper site does not occur immediately after nitrite binding. Proton affinity calculations are indicative of substantial pKa differences between different states of the T2 site. The calculations further suggest that the reaction does not proceed until uptake of a second proton from the bulk solution. They also indicate that Asp‐92 may play both a key role as a proton donor to the substrate, and a structural role in promoting catalysis. In the D92N mutant another base, presumably a nearby histidine (His‐249) may take the role as the proton donor. On the basis of these model calculations and available experimental evidence, an ordered reaction mechanism for the reduction of nitrite is suggested. An investigation of the binding modes of the nitric oxide product and the nitrite substrate to the model site has also been made, indicating that nitric oxide prefers to bind in an end‐on fashion to the reduced T2 site. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 528–539, 2007
Similarity of RNA secondary structures
Authors: Li Chun , Wang Ai‐hua , Xing Lili
Published: December 2006

In this article, we propose a relatively similar measure to compare RNA secondary structures. We first transform an RNA secondary structure into a special sequence representation. Then, on the basis of symbolic sequence complexity, we obtain the relative distance of RNA secondary structures. The examination of similarities/dissimilarities of a set of RNA secondary structures at the 3′‐terminus of different viruses illustrates the utility of the approach. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 508–512, 2007
Free energy profiles for monomer capture in Grubbs‐ and SHOP‐type olefin polymerization catalysts: A constraint ab initio molecular dynamics study
Authors: Yang Sheng‐Yong , Xiang MIng‐Li , Chen Li‐Juan , Xie Guo‐Bin , Shi Bing , Wei Yu‐Quan , Ziegler Tom
Published: December 2006

Density functional theory together with Car‐Parrinello ab initio molecular dynamics simulation has been used to investigate the free energy profiles (FEP) of monomer capture in Grubbs‐ and SHOP‐type olefin polymerization catalysts. The FEPs along the reaction coordinates at 300 K were determined directly by a point wise thermodynamic integration technique. Comparison between potential energy profile (PEP) and the FEP has been made. The results show that, for both catalysts, the PEP for the monomer ethylene uptake by the metal center is a typical Morse curve without energy barrier. However, a small barrier (1.8 kcal/mol for Grubbs catalyst and 2.4 kcal/mol for SHOP catalyst) exists on the FEP. The π complexation energy on the FES at 300 K is higher by 10–12 kcal/mol over that on the PES. The differences between FES and PES are due to entropy contribution. Slow growth simulations on the ethylene capture process show that the ethylene attacks the metal center by an asynchronous mode. This indicates that the forming of the π‐bonding between the metal and ethylene is initiated by electrophilic attack of the metal to one of the ethylene carbons. © 2006 Wiley Periodicals, Inc. J Comput Chem 28: 513–518, 2007
P2Y2 receptors induced cell surface redistribution of αv integrin is required for activation of ERK 1/2 in U937 cells
Authors: Chorna Nataliya E. , Chevres Migdalia , Santos‐Berrios Cynthia , Orellano Elsie A. , Erb Laurie , González Fernando A.
Published: December 2006

Nucleotides released from cells due to stress, injury or inflammation, induce mitogenic effects in monocytes via activation of P2Y2 nucleotide receptors (P2Y2Rs). Here we show that P2Y2 nucleotide receptors in U937 monocytic cells regulate the activation of extracellular signal‐regulated kinases 1 and 2 (ERK 1/2) by inducing the clustering of αv integrins. The activation of phosphatidylinositol 3‐kinase by P2Y2R ligands was required for αv clustering, suggesting a means whereby two different classes of receptors communicate to induce mitogenic responses in monocytic cells. P2Y2R‐induced αv clustering was also associated with a flattened phenotype of the U937 cells, consistent with the role of the P2Y2R in regulating early events in cell migration. J. Cell. Physiol. 211: 410–422, 2007. © 2006 Wiley‐Liss, Inc.
Downregulation of catalase by reactive oxygen species via PI 3 kinase/Akt signaling in mesangial cells
Authors: Venkatesan Balachandar , Mahimainathan Lenin , Das Falguni , Ghosh‐Choudhury Nandini , Ghosh Choudhury Goutam
Published: December 2006

Reactive oxygen species (ROS) contribute to many glomerular diseases by targeting mesangial cells. ROS have been shown to regulate expression of many antioxidant enzymes including catalase. The mechanism by which the expression of catalase protein is regulated by ROS is not precisely known. Here we report that increased intracellular ROS level by hydrogen peroxide (H2O2) reduced the expression of catalase. H2O2 increased phosphorylation of Akt kinase in a dose‐dependent and sustained manner with a concomitant increase in the phosphorylation of FoxO1 transcription factor. Further analysis revealed that H2O2 promoted rapid activation of phosphatidylinositol (PI) 3 kinase. The PI 3 kinase inhibitor Ly294002 and expression of tumor suppressor protein PTEN inhibited Akt kinase activity, resulting in the attenuation of FoxO1 phosphorylation and preventing the downregulating effect of H2O2 on catalase protein level. Dominant negative Akt attenuated the inhibitory effect of H2O2 on expression of catalase. Constitutively active FoxO1 increased the expression of catalase. However, dominant negative FoxO1 inhibited catalase protein level. Catalase transcription was reduced by H2O2 treatment. Furthermore, expression of dominant negative Akt and constitutively active FoxO1 increased catalase transcription, respectively. These results demonstrate that ROS downregulate the expression of catalase in mesangial cells by PI 3 kinase/Akt signaling via FoxO1 as a target. J. Cell. Physiol. 211: 457–467, 2007. © 2006 Wiley‐Liss, Inc.
Activation of Prn‐p gene and stable transfection of Prn‐p cDNA in leukemia MEL and neuroblastoma N2a cells increased production of PrPC but not prevented DNA fragmentation initiated by serum deprivation
Authors: Gougoumas Dimitrios D. , Vizirianakis Ioannis S. , Triviai Ioanna N. , Tsiftsoglou Asterios S.
Published: December 2006

Prion protein (PrPC) via its isoform PrPSC is involved in the pathogenesis of transmissible spongiform encephalopathies (TSEs). We observed that murine erythroleukemia (MEL) cells arrested in phase G1 undergo transcriptional activation of Prn‐p gene. Here, we explored the potential role of activation of Prn‐p gene and cytosolic accumulation of PrPC in growth arrest, differentiation, and apoptotic DNA fragmentation by stably transfecting MEL and N2a cells with Prn‐p cDNA. Stably transfected MEL cells (clones # 6, 12, 20, 38, and 42) were assessed for growth and differentiation, while clones N2a13 and N2a8 of N2a cells for growth and apoptosis by flow cytometry using Annexin V and propidium iodide (PI). Our results indicate that (a) Induction of terminal differentiation of stably transfected MEL cells led to growth arrest, activation of Prn‐p gene, concomitant expression of transfected Prn‐p cDNA, suppression of bax gene, cytosolic accumulation of PrPC, and DNA fragmentation. The latter was also induced in non‐differentiated MEL cells growing under serum‐free conditions; (b) similarly, serum deprivation promoted growth arrest, apoptosis/necrosis associated with DNA fragmentation in parental N2a and N2a13 cells that produced relative high level of PrPC and not PrPSC. These data indicate that activation of Prn‐p gene and expression of transfected Prn‐p cDNA in cells of both hematopoietic and neuronal origin occurred concomitantly, and led to cytosolic accumulation of PrPC and DNA damage induced by serum deprivation. PrPC production failed to protect DNA fragmentation induced by serum deprivation. The question how does PrPC contribute to growth arrest and DNA fragmentation is discussed. J. Cell. Physiol. 211: 551–559, 2007. © 2006 Wiley‐Liss, Inc.
Reduced aggression in mice lacking GABA transporter subtype 1
Authors: Liu Guo‐Xiang , Liu Shuai , Cai Guo‐Qiang , Sheng Zhe‐Jing , Cai You‐Qing , Jiang Jie , Sun Xia , Ma Sun‐Kai , Wang Long , Wang Zhu‐Gang , Fei Jian
Published: December 2006

Dysregulation of the brain GABAergic system has been implicated in the pathophysiology of violence and aggression. As a key regulator of central GABAergic activity, dysfunction of the GABA transporter subtype 1 (GAT1) represents a potential mechanism mediating pathologic aggression. We provide evidence that GAT1−/− mice and GAT1+/− mice exhibit lower aggressive behavior both in home cage resident–intruder test and neutral arena resident–intruder test, compared to wild‐type mice (GAT1+/+). The pharmacologic effects of the GAT1 inhibitor, tiagabine and the GABAA receptor antagonist, bicuculline have been assessed in GAT1+/+ mice: tiagabine inhibits attacks but bicuculline induces attacks. Compared to GAT1+/− and +/+ mice, the GAT1−/− mice displayed a normal circadian pattern of home cage activity, but more activity overall. Meanwhile, reduced testosterone concentration was found in GAT1−/− mice compared to GAT1+/+ mice but not in GAT1+/+ mice treated with tiagabine, suggesting that testosterone is not directly involved in GAT1 mediated aggressive behavior regulation. These results showed that GAT1 is an important target involved in the regulation of aggressive behavior in mice, and long‐term dysfunction of GAT1 may also result in the alteration of testosterone secretion. © 2006 Wiley‐Liss, Inc.
Diurnal variations in summer season precipitation in India
Authors: Sen Roy Shouraseni , Balling Robert C.
Published: December 2006

In the present study, we have analyzed the spatial patterns in the diurnal cycle of precipitation over the Indian subcontinent. We assembled hourly precipitation data for 78 stations spread across the Indian subcontinent for the period 1980 to 2000. On the basis of the results of the first harmonic, we found the presence of a distinct diurnal cycle over most of the Indian subcontinent for frequency, total, and intensity of precipitation events. The standardized amplitudes, indicative of the strength of diurnal cycle over a region, are strongest in peninsular India, with greater than 80% explained variance. The diurnal spatial patterns are broadly a result of the interaction of local orography and convectional processes. The time of maximum precipitation along the west coast is predominantly concentrated a few hours after midnight to predawn hours. The interiors of the subcontinent generally experience late afternoon to early evening showers, which may be attributed to local convective processes. The time of maximum for total amount of precipitation are mostly about half an hour to 1 h before the time of maximum for the frequency. The overall patterns of diurnal cycle were also found to be robust against interannual variations, in the form of ENSO and La Niña years. Copyright © 2006 Royal Meteorological Society
Raman and ab initio study of the conformational isomerism in the 1‐ethyl‐3‐methyl‐imidazolium bis(trifluoromethanesulfonyl)imide ionic liquid
Authors: Lassègues J. C. , Grondin J. , Holomb R. , Johansson P.
Published: December 2006

The calculated and experimental Raman spectra of the (EMI+)TFSI− ionic liquid, where EMI+ is the 1‐ethyl‐3‐methylimidazolium cation and TFSI− the bis(trifluoromethanesulfonyl)imide anion, have been investigated for a better understanding of the EMI+ and TFSI− conformational isomerism as a function of temperature. Characteristic Raman lines of the planar (p) and non‐planar (np) EMI+ conformers are identified using the reference (EMI+)Br− salt. The anion conformer of C2 symmetry is confirmed to be more stable than the cis (C1) one by 4.5 ± 0.2 kJ mol−1. At room temperature, the population of trans (C2) anions and np cations is 75 ± 2% and 87 ± 4%, respectively. Fast cooling quenches a metastable glassy phase composed of mainly C2 anion conformers and p cation conformers, whereas slow cooling gives a crystalline phase composed of C1 anion conformers and of np cation conformers. Copyright © 2006 John Wiley & Sons, Ltd.
High‐resolution stimulated Raman spectroscopy and analysis of the ν1 stretching band of GeD4
Authors: Boudon V. , Radhouani D. , Loëte M. , Martínez R. Z. , Bermejo D.
Published: December 2006

The high‐resolution stimulated Raman spectrum of the ν1 band of GeD4 with natural isotopic abundance germanium has been recorded. It has been analyzed as part of the ν1/ν3 stretching dyad. The ν1 and ν3 band centers have been deduced for all the isotopologues. Copyright © 2006 John Wiley & Sons, Ltd.
The figure of merit of a photonic-crystal fiber beam delivery and response-signal collection for nanoparticle-assisted sensor arrays
Authors: Alfimov M V , Zheltikov A M
Published: December 2006

Photonic-crystal fibers (PCFs) are shown to offer an advantageous flexible architecture of beam delivery and response-signal collection for nanoparticle-assisted sensor arrays, including nose-on-a-chip devices. Within a broad range of numerical aperture values, the figure of merit for PCF response-signal collection in such systems is shown to scale as (NA/a)2 with the numerical aperture of the fiber NA and the size of nanoparticles a. For the available high-NA silica-air PCFs, figures of merit as high as 104 are predicted for specific sensor-array arrangements.
An innovative solid-state laser for engine ignition
Authors: Kofler H , Tauer J , Tartar G , Iskra K , Klausner J , Herdin G , Wintner E
Published: December 2006

A compact high peak power, passively Q-switched, longitudinally diode-pumped laser was specially constructed for laser ignition. Nd:YAG was chosen as laser active medium and Cr4+:YAG as the saturable absorber medium. For pumping, a laser diode emitting at 808 nm with an output power of up to 300 W and pulse duration of up to 500 μs was employed. Experimental studies were carried out to find the optimum laser design parameters. These are the output coupler reflectivity, initial transmission of the saturable absorber, doping concentration of the Nd:YAG, oscillator length and the pump light distribution within the Nd:YAG crystal. Single pulses at 1064 nm with energies of 6 mJ and durations under 1.5 ns were achieved in a TEM00 mode.
Wavelength-spacing tunable multi-wavelength erbium-doped fiber laser incorporating a semiconductor optical amplifier
Authors: Chen D , Ou H , Fu H , Qin S , Gao S
Published: December 2006

A multi-wavelength erbium-doped fiber laser incorporating an semiconductor optical amplifier (SOA) based on a tunable Mach-Zehnder interferometer (as a comb filter) is proposed. Wavelength-spacing can be continuously tuned and multi-wavelength lasing with wavelength spacings of 0.4 nm, 0.8 nm, and 1.6 nm is demonstrated. The output of the proposed multi-wavelength laser is rather stable at room temperature and the output spectra can be adjusted by controlling the bias current of the SOA and the power of the pump laser diode.
Internal-loss-limited maximum operating temperature and characteristic temperature of quantum dot laser
Authors: Jiang L , Asryan L V
Published: December 2006

Carrier-density-dependent internal optical loss sets an upper limit for operating temperatures and considerably reduces the characteristic temperature of a quantum dot laser. Such internal loss also constrains the shallowest potential well depth and the smallest tolerable size of a quantum dot at which the lasing can be attained. At the maximum operating temperature or when any parameter of the structure is equal to its critical tolerable value, the characteristic temperature drops to zero.
Nonlinear induced polarization dependent scattering in solid state azo-dye films
Authors: Dubrovkin A M , Jung Y , Kozenkov V M , Magnitskii S A , Nagorskiy N M
Published: December 2006

Polarization optical anisotropy of scattering in solid-state azo-dye films induced by nonlinear absorption has been registered for the first time. Optical anisotropy of scattering has been initiated by sequence of femtosecond pulses and has been detected in solid state nanostructural amorphous thin films formed out of pure azo-dye AD-1. It was found that efficiency of scattering strongly depends on polarization of incident light.
L-band Brillouin-Erbium fiber laser pumped with 1480 nm pumping scheme in a linear cavity
Authors: Al-Mansoori M H , Naji A W , Iqbal S J , Abdullah M K , Mahdi M A
Published: December 2006

In this paper, a multiwavelength linear-cavity Brillouin-Erbium fiber laser pumped by a 1480 nm pump laser is demonstrated to operate in the L-band region. The issue of low gain efficiency of L-band in Erbium-doped fiber pumped with 980 nm pump lasers is resolved with this pumping scheme. The amount of 1480 nm pump power to produce the first Brillouin Stokes line oscillating in the cavity is 23.4 mW only. The proposed laser configuration has a wide tuning range of 16 nm from 1591 to 1607 nm with six Brillouin Stokes lines within this tuning range. The maximum number of 23 Brillouin Stokes lines with a spacing of 0.089 nm is achieved by setting the Brillouin pump wavelength at 1595.5 nm and its power is set at 3.2 mW.
Growth arrest‐specific gene 6 and Axl signaling enhances gastric cancer cell survival via Akt pathway
Authors: Sawabu Tateo , Seno Hiroshi , Kawashima Tomoko , Fukuda Akihisa , Uenoyama Yoshito , Kawada Mayumi , Kanda Naoki , Sekikawa Akira , Fukui Hirokazu , Yanagita Motoko , Yoshibayashi Hiroshi , Satoh Seiji , Sakai Yoshiharu , Nakano Toru , Chiba Tsutomu
Published: December 2006

Activation of tyrosine kinases is an important factor during cancer development. Axl, one of the receptor tyrosine kinases, binds to the specific ligand growth arrest‐specific gene 6 (Gas6), which encodes a vitamin K‐dependent γ‐carboxyglutamyl protein. Although many receptor tyrosine kinases and their ligands are involved in gastric carcinogenesis, whether Gas6‐Axl signaling is involved in gastric carcinogenesis has not been elucidated. The aim of this study was to investigate the expression of Gas6 and Axl in gastric cancer and also their roles during gastric carcinogenesis. mRNA and protein of Gas6 and Axl were highly expressed in a substantial proportion of human gastric cancer tissue and cell lines, and Gas6 expression was significantly associated with lymph node metastasis. With recombinant Gas6 and a decoy‐receptor of Axl in vitro, we demonstrated that Gas6‐Axl signaling pathway enhanced cellular survival and invasion and suppressed apoptosis via Akt pathway. Our results suggests that Gas6‐Axl signaling plays a role during gastric carcinogenesis, and that targeting Gas6‐Axl signaling could be a novel therapeutic for gastric cancer. © 2006 Wiley‐Liss, Inc.
Elevated urokinase‐specific surface receptor expression is maintained through its interaction with urokinase plasminogen activator
Authors: Mahanivong Chitladda , Yu Jianqiang , Huang Shuang
Published: December 2006

Urokinase plasminogen activator (uPA) and its receptor (uPAR) are overexpressed in various neoplasms, and play a key role in tumor progression and metastasis. In this study, we examined uPA and uPAR expression in a variety of human breast cancer cell lines and found that lines with elevated uPA expression also exhibited high uPAR expression, suggesting the possibility that uPA and uPAR are regulated in concert. To test this possibility, we introduced antisense uPA RNA and antisense uPAR RNA in MDA‐MB‐231 and BT‐549 lines that express high levels of uPA and uPAR. Antisense uPA RNA not only downregulated uPA expression, but also greatly reduced uPAR expression in both lines. However, antisense uPAR RNA‐reduced uPAR expression with no apparent inhibitory effect on the levels of uPA. These results indicate that expression of uPAR requires uPA but not vice versa. With a panel of uPA and uPAR monoclonal antibodies (mAbs), we observed that the mAbs disrupting uPA and uPAR interaction, rather than mAb inhibiting uPA protease activity, reduced uPAR expression. Moreover, adding soluble single chain uPA (scuPA) to MDA‐MB‐231 or BT‐549 cells expressing antisense uPA mRNA‐restored uPAR expression. These findings suggest that uPA dictates uPAR expression and that uPA binding to uPAR transmits signals for uPAR expression. Finally, we provided evidence that Fyn, a Src family kinase, is involved in uPA‐induced uPAR expression. © 2006 Wiley‐Liss, Inc.
Connexin 32 potentiates vinblastine‐induced cytotoxicity in renal cell carcinoma cells
Authors: Sato Hiromi , Senba Hironobu , Virgona Nantiga , Fukumoto Keiko , Ishida Tatsuya , Hagiwara Hiromi , Negishi Etsuko , Ueno Koichi , Yamasaki Hiroshi , Yano Tomohiro
Published: December 2006

We have reported that connexin (Cx) 32 gene, a member of gap junction protein family, acts as a tumor suppressor gene in human renal cell carcinoma (RCC). Of solid tumors, RCC is one of the most chemoresistant cancers, and there is no effective cancer chemotherapy against RCC at present. In this study, we examined if the combination of Cx32‐dependent tumor‐suppressive effect and vinblastine (VBL), a chemotherapeutic agent which has been utilized for clinical RCC treatment, could be effective in enhancing the sensitivity of RCC to VBL treatment. Cx32 expression in a human metastatic RCC cell (Caki‐1 cell) significantly enhanced in vitro and in vivo VBL‐induced cytotoxicity on the cell. Cx32 expression in the RCC cells potentiated VBL‐induced apoptosis compared to the Cx32‐negative RCC cells in vitro as well as in vivo. The enhancing apoptosis in the RCC cells by Cx32 mainly depended on the decrease of P‐glycoprotein (P‐gp), a multidrug resistance gene‐1 (MDR‐1) product responsible for reduction of VBL accumulation into the cells. We also observed that silencing of Cx32 by short interfering RNA (siRNA) treatment elevated the level of P‐gp in Caki‐1 cells and that inhibition of P‐gp function enhanced VBL‐induced apoptosis in the RCC cells. These results suggest that Cx32 is effective to enhance VBL‐induced cytotoxicity in Caki‐1 cells via the reduction of P‐gp. Overall, it seems that the combination of Cx32‐dependent tumor‐suppressive effect and VBL is promising as a new cancer therapy against RCC. © 2006 Wiley‐Liss, Inc.