bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical and photoelectrical properties of a GaAs‐based p‐i‐n structure grown by MOVPE
Authors: Begotti M. , Longo M. , Magnanini R. , Tarricone L. , Gombia E. , Mosca R. , Lynch M. , Barnham K. , Mazzer M. , Hill G.
Published: September 2005

A GaAs‐based p‐i‐n junction grown by MOVPE and using the high purity and low dissociation temperature tertiarybutylarsine (TBAs) precursor, was studied. Such a structure is suitable to play the role of a sub‐cell in a multi‐junction photovoltaic device. Electrical measurements showed excellent properties of the junction; in particular, the forward current‐voltage characteristic was detected over ten orders of magnitude, showing: a rectification ratio of about 1010 at 1.2 V, low reverse current and low series resistance. Capacitance measurements confirmed the low contaminant concentration of the unintentionally doped intrinsic region (of the order of 1014 cm–3). A fill factor equal to 0.81, confirming low background doping and indicating low series resistance, has been measured for the illuminated junction. The long wavelength tail of the spectral response, controlled by the diffusion length of the minority carriers (holes) in the n‐type base region of the junction, has been fitted, giving a hole diffusion length equal to 2 µm. The comparison with an identical structure, grown by MOVPE with the use of the traditional arsine precursor, showed that the p‐i‐n junction here studied has some superior electrical and photoelectrical properties, in particular a lower dark‐current. Although the primary use for devices of this kind is as a part of a more complex heterostructure, the p‐i‐n junction studied in this work also achieves a good projected conversion efficiency as a single junction cell (21.4 ± 1)% at AM1.5g. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth aspects of AlGaAs/GaAs tunnel diodes for multijunction solar cells
Authors: Timò G. , Flores C. , Campesato R.
Published: September 2005

Growth aspects related to AlGaAs/GaAs tunnel diodes for multijunction solar cell structures are presented. Test structures have been grown in order to show the correct way for checking the thermal resistance of tunnel diodes. AlGaAs:C lattice contraction as a function of carbon concentration and growth temperature has been studied by using XRD, Hall and Room temperature photoluminescence characterisation. The XRD experimental results have been successfully compared with the lattice contraction model reported by W.E Hoke et al. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Why CuInGaSe2 and CdTe polycrystalline thin film solar cells are more efficient than the corresponding single crystal?
Authors: Bosio A. , Romeo N. , Podestà A. , Mazzamuto S. , Canevari V.
Published: September 2005

Recently, very high conversion efficiencies in thin film polycrystalline solar cells have been reported. In particular it was reached an efficiency record both for CuInGaSe2 (CIGS) and CdTe that are 19.2% and 16.5% respectively. We will briefly describe the technological methods used to fabricate these thin film solar cells. Besides, we will try to explain the reason why thin film polycrystalline devices can achieve conversion efficiency comparable with those shown by single crystal solar cells (mono‐Si or poly‐Si). We will take into consideration the tricks present in both the methods that allow to make the CIGS/CdS and CdTe/CdS thin film solar cells with excellent performances. We will show also, that these technologies are ripe for an “inline” industrial production and this makes thin film solar cells the best candidates for the large scale utilisation of photovoltaic energy conversion. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of antimony doping on microdefect formation in Czochralski grown silicon crystals
Authors: Porrini M.
Published: September 2005

The impact of antimony doping on the formation of vacancy‐ and interstitial‐type microdefects in Czochralski silicon is studied by growing test crystals with different Sb doping levels, in the range from 0 (undoped) to 3 × 1018 cm–3, and with different pulling rates. Antimony is found to cause a shift from interstitial‐ to vacancy‐type microdefects, observable already at a concentration of ≈1017 cm–3. The shift coefficient K for antimony is estimated to be 7.2 × 10–19 cm3. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crystal growth and structural refinement of NaMn7O12
Authors: Gilioli E. , Licci F. , Calestani G. , Prodi A. , Gauzzi A. , Salviati G.
Published: September 2005

We report the crystal growth and the structural refinement of NaMn7O12, a manganite having a double perovskite structure. As in many similar compounds, there is coexistence of Mn3+ and Mn4+ but in this material they orderly occupy different sites for crystallographic reasons. Therefore, this peculiar structure can be considered as a model system for studying complex mechanisms such as charge, orbital and spin ordering. High purity bulk samples and “large” single crystals are needed to study tiny modifications in the crystallographic and magnetic structures associated to the ordering phenomena. Almost single phase (more than 96% pure) and single crystals (up to about 150 µm) of NaMn7O12 were synthesized by solid state reaction under pressure in a multi‐anvil apparatus. Single crystal x‐ray diffraction and SEM analysis have been used to characterize the crystals. The structure refinement indicates that NaMn7O12 crystallizes in the cubic Im3 space group, with a = 7.312 Å and Z = 2. Further studies are in progress to optimize the synthesis conditions, in order to grow larger crystals. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth kinetics, adsorption and morphology of sucrose crystals from aqueous solutions in the presence of raffinose
Authors: Sgualdino G. , Aquilano D. , Fioravanti R. , Vaccari G. , Pastero L.
Published: September 2005

Experimental growth kinetics of the most important F forms of sucrose crystal, {100}, {110}, {10$ \bar 1 $} and {$ \bar 1 $$ \bar 1 $0}, has been investigated at T = 40 °C within a range of supersaturations (σ = 0.040 and 0.080), in the presence of varying raffinose concentrations (0.0 ≤ Craff ≤ 8.0% H2O). Raffinose dramatically slows down the growth rate of the first three forms, modifies the shape of their growth isotherms and can induce dead zones as well, the effects increasing with its concentration. However, the screw dislocation mechanism maintains. The comparison between Kubota‐Mullin and Cabrera‐Vermilyea kinetic models shows that the first one better describes our experimental data. This allows to deduce that the raffinose adsorption mainly occurs at the kinks sites of all the interested forms. Moreover, the values of the effectiveness coefficient of KM model shows the combined effects of supersaturation and raffinose concentration in the growth solutions. On the contrary, the {$ \bar 1 $$ \bar 1 $0} form is weakly affected by raffinose, owing to the low structural compatibility between its kinks and the additive molecules. Finally, the changes of the crystal morphology, induced by the highly anisotropic kinetic effects, were studied as well. Increasing raffinose concentration and supersaturation produces conflicting effects on the morphology: the first one promotes crystals elongated in the [010] direction and reduces the number of forms on the crystals, while supersaturation acts in the opposite sense. Ratios among the main dimensions of crystals are critically discussed to evaluate their final shapes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Different contributions of insulin resistance and beta‐cell dysfunction in overweight Israeli Arabs with IFG and IGT
Authors: Abdul‐Ghani Muhammad A. , Sabbah Muhammad , Kher Joseph , Minuchin Oscar , Vardi Pnina , Raz Itamar
Published: September 2005

Background

Impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) are both intermediate stages that exist between normal glucose tolerance and overt type 2 diabetes. Epidemiological studies demonstrated that the two categories define distinct populations. In this study, we examined the contributions of insulin resistance and beta‐cell dysfunction to both states in overweight subjects of Arab origin.

Methods

Twelve subjects with isolated IFG, 10 with isolated IGT, and 20 with IFG and IGT (combined glucose in tolerance—CGT) were compared with 30 subjects with normal glucose tolerance (NGT) subjects; all were of Arab origin and were overweight or obese. Different indices for insulin resistance and beta‐cell function were calculated from oral glucose tolerance (OGTT) values.

Results

Subjects with isolated IFG and CGT were more obese and had significantly higher values of insulin resistance than subjects with isolated IGT and NFG. There was no significant difference between the insulin resistance in subjects with isolated IGT and that in subjects with NGT. Indices of beta cell function were severely reduced among subjects with isolated IGT and CGT when compared with those with both isolated IFG and NGT, while subjects with isolated IFG had similar beta‐cell indices to subjects with NGT.

Conclusion

These data demonstrate that beta‐cell dysfunction and insulin resistance contribute differently to the pathogenesis of IFG and IGT among overweight Arab subjects. Copyright © 2005 John Wiley & Sons, Ltd.
Regional sustainable development in France: assessing the environmental implications
Authors: Bertrand F. , Larrue C.
Published: September 2005

This article considers the environmental dimension of regional sustainable development in France. The first part evaluates the position of the environment in regional sustainable development policies using two levels of analysis. First, it examines the stated objectives for regional sustainable development that relate to a balanced integration of the environmental dimension in relation to the economic and social dimensions. Second, it demonstrates how efforts to implement regional sustainable development (RSD) invariably lead to domination by environmental factors, as a consequence of well established environmental policies. Thereafter, a critical analysis of this outcome is presented, illustrating how the disparity between what is said and done has produced an ambiguous notion of sustainable development (SD), and how different actors have adopted strongly opposing views. This confusion has created resistance by environmental actors, who perceive sustainable development as potentially diluting environmental demands. The article concludes by discussing the possible future role of the environment within regional sustainable development. Copyright © 2005 John Wiley & Sons, Ltd and ERP Environment.
Water‐Soluble Arene Ruthenium Complexes Containing a trans‐1,2‐Diaminocyclohexane Ligand as Enantioselective Transfer Hydrogenation Catalysts in Aqueous Solution
Authors: Canivet Jérôme , Labat Gael , Stoeckli‐Evans Helen , Süss‐Fink Georg
Published: September 2005

The cationic chloro complexes [(arene)Ru(H2N∩NH2)Cl]+ (1: arene = C6H6; 2: arene = p‐MeC6H4iPr; 3: arene = C6Me6) have been synthesised from the corresponding arene ruthenium dichloride dimers and enantiopure (R,R or S,S) trans‐1,2‐diaminocyclohexane (H2N∩NH2) and isolated as the chloride salts. The compounds are all water‐soluble and, in the case of the hexamethylbenzene derivative 3, the aqua complex formed upon hydrolysis [(C6Me6)Ru(H2N∩NH2)OH2]2+ (4) could be isolated as the tetrafluoroborate salt. The molecular structures of 3 and 4 have been determined by single‐crystal X‐ray diffraction analyses of [(C6Me6)Ru(H2N∩NH2)Cl]Cl and [(C6Me6)Ru(H2N∩NH2)OH2][BF4]2. Treatment of [Ru2(arene)2Cl4] with the monotosylated trans‐1,2‐diaminocyclohexane derivative (TsHN∩NH2) does not yield the expected cationic complexes, analogous to 1–3 but the neutral deprotonated complexes [(arene)Ru(TsN∩NH2)Cl] (5: arene = C6H6; 6: arene = p‐MeC6H4iPr; 7: arene = C6Me6; 8: arene = C6H5COOMe). Hydrolysis of the chloro complex 7 in aqueous solution gave, upon precipitation of silver chloride, the corresponding monocationic aqua complex [(C6Me6)Ru(TsHN∩NH2)(OH2)]+ (9) which was isolated and characterised as its tetrafluoroborate salt. The enantiopure complexes 1–9 have been employed as catalysts for the transfer hydrogenation of acetophenone in aqueous solution using sodium formate and water as a hydrogen source. The best results were obtained (60 °C) with 7, giving a catalytic turnover frequency of 43 h–1 and an enantiomeric excess of 93 %. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis, Structure and Magnetic Properties of a Novel Linear CuII‐Trimer Complex
Authors: Pashchenko Vladimir , Brendel Bernhard , Wolf Bernd , Lang Michael , Lyssenko Konstantin , Shchegolikhina Olga , Molodtsova Yulia , Zherlitsyna Larisa , Auner Norbert , Schütz Florian , Kollar Marcus , Kopietz Peter , Harrison Neil
Published: September 2005

A new hexanuclear copper(II) sandwich complex based on two 10‐membered macrocyclic phenylsiloxanolate ligands, {Cu6[(C6H5SiO2)5]2(OH)2(C10H8N2)2}·4(DMF)·3(H2O) (1), was synthesized and characterized by single‐crystal X‐ray diffraction and measurements of the magnetic susceptibility and isothermal magnetization. The cluster compound crystallizes in the triclinic system, space group P$\bar {1}$ (No. 2), with a = 14.925(3) Å, b = 16.745(2) Å, c = 23.053(3) Å, α = 83.079(9)°, β = 84.836(13)°, γ = 65.019(17)°, and Z = 2. The unit cell contains two identical molecules, each consisting of six interacting Cu2+ (S = 1/2) ions. Within the molecule, the six Cu2+ ions are arranged in two almost linear, parallel trimers. While pairs of oxygen atoms link the Cu2+ ions within the trimers, single oxygen atoms residing at the ends of the trimers provide the strongest intertrimer bonds. Magnetic measurements reveal an antiferromagnetic intratrimer exchange interaction, J/kB = 85 K, as the dominant magnetic coupling of the complex. By introducing a weak antiferromagnetic intertrimer coupling, J′/kB = 3.5 K, a satisfactory description of the magnetic behavior over a wide range of temperature and magnetic field is obtained. The departure of the model curves from the data at the lowest available temperature indicates the presence of additional, weak intra‐ and/or intermolecular interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A Library of Peralkylated Bis‐guanidine Ligands for Use in Biomimetic Coordination Chemistry
Authors: Herres‐Pawlis Sonja , Neuba Adam , Seewald Oliver , Seshadri Tarimala , Egold Hans , Flörke Ulrich , Henkel Gerald
Published: September 2005

A series of bis‐guanidine ligands designed for use in biomimetic coordination chemistry has been extended to a library matrix combining unprecedented substitutional flexibility within the guanidyl residues with a wide range of aliphatic and aromatic spacers connecting these functionalities. The underlying protocol can be used with predefined ureas as well as secondary amines to build up these units by reaction with phosgene if the ureas are otherwise unavailable. In the latter case, the resulting urea intermediates do not have to be isolated as the reaction proceeds further with additional phosgene to yield a chloroformamidinium chloride which is transformed into the bis‐guanidine functionality by subsequent reaction with a suitable primary diamine in the presence of triethylamine as an auxiliary base. This concept has been used to synthesise and characterise more then two dozen different bis‐guanidines based on 12 discrete monoguanidine units and seven different spacers. These spacers have been chosen such that the most important phenotypes have been dealt with and which range from rigid to more flexible scaffolds. In addition to spacers with no metal‐binding capabilities, other species containing further donor functions such as N‐methyldiphenyleneamine or pyridine‐2,6‐diyl have also been used. The substitution patterns of the guanidine residues can be classified into acyclic and cyclic types. Among the cyclic types, one subset is characterised by five‐ or six‐membered heterocycles containing both the amino nitrogen atoms and another one by individual N‐heterocyclic systems for each amino nitrogen. Structurally characterised examples are 2‐{2‐[2‐(tetramethylguanidi­no)ethoxy]ethoxy}‐1‐(tetramethylguanidino)ethane (TMG2doo) in its diprotonated form and 2,2′‐bis[2N‐(1,1′,3,3′‐tetramethylguanidine)]diphenyleneamine (TMG2PA) as wellas N1,N3‐bis(dimorpholinomethylene)propane‐1,3‐diamine (DMorphG2p) as free bases. For the permethylated bis‐guanidine derivatives, the barrier to rotation around the (C=N)guanidine bond has been determined by means of temperature‐dependent EXSY 1H NMR spectroscopy to range between 54 and 79 kJ mol–1 depending on the type of spacer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Ring Opening of Aziridines with Silylated Nucleophiles under Neutral Conditions
Authors: Wu Jie , Sun Xiaoyu , Xia Hong‐Guang
Published: September 2005

Ring‐opening of aziridines with silylated nucleophiles in DMF without any catalysts afforded the corresponding products in good to excellent yields under extremely mild reaction conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Development of partial rock veneers by root throw in a subalpine setting
Authors: Osterkamp W. R. , Toy T. J. , Lenart M. T.
Published: September 2005

Rock veneers stabilize hillslope surfaces, occur especially in areas of immature soil, and form through a variety of process sets that includes root throw. Near Westcliffe, Colorado, USA, data were collected from a 20 × 500 m transect on the east slope of the Sangre de Cristo Mountains. Ages of pit/mound complexes with rock fragments exposed at the surface by root throw ranged from recent (freshly toppled tree) to unknown (complete tree decay). Calculations based on dimensions of the pit/mound complexes, estimated time of tree toppling, sizes of exposed rock fragments, and percentage rock covers at pit/mound complexes, as well as within the transect area, indicate that recent rates of root throw have resulted in only partial rock veneering since late Pleistocene deglaciation. Weathering of rock fragments prevents development of an extensive rock veneer and causes a balance, achieved within an estimated 700 years, between the rates of rock‐fragment exposure by root throw and clast disintegration by chemical reduction. The estimated rate of rock‐fragment reduction accounts for part of the fluvial sediment yields observed for forested subalpine areas of western North America. Copyright © 2005 John Wiley & Sons, Ltd.
Spatial structures of stream and hillslope drainage networks following gully erosion after wildfire
Authors: Moody John A. , Kinner David A.
Published: September 2005

The drainage networks of catchment areas burned by wildfire were analysed at several scales. The smallest scale (1–1000 m2) representative of hillslopes, and the small scale (1000 m2 to 1 km2), representative of small catchments, were characterized by the analysis of field measurements. The large scale (1–1000 km2), representative of perennial stream networks, was derived from a 30‐m digital elevation model and analysed by computer analysis.

Scaling laws used to describe large‐scale drainage networks could be extrapolated to the small scale but could not describe the smallest scale of drainage structures observed in the hillslope region. The hillslope drainage network appears to have a second‐order effect that reduces the number of order 1 and order 2 streams predicted by the large‐scale channel structure. This network comprises two spatial patterns of rills with width‐to‐depth ratios typically less than 10. One pattern is parallel rills draining nearly planar hillslope surfaces, and the other pattern is three to six converging rills draining the critical source area uphill from an order 1 channel head. The magnitude of this critical area depends on infiltration, hillslope roughness and critical shear stress for erosion of sediment, all of which can be substantially altered by wildfire. Order 1 and 2 streams were found to constitute the interface region, which is altered by a disturbance, like wildfire, from subtle unchannelized drainages in unburned catchments to incised drainages. These drainages are characterized by gullies also with width‐to‐depth ratios typically less than 10 in burned catchments. The regions (hillslope, interface and channel) had different drainage network structures to collect and transfer water and sediment. Copyright © 2005 John Wiley & Sons, Ltd.
A multi‐level panel STAR model for US manufacturing sectors
Authors: Fok Dennis , van Dijk Dick , Franses Philip Hans
Published: September 2005

We introduce a multi‐level smooth transition model for a panel of time series, which can be used to examine the presence of common nonlinear business cycle features across many variables. The model is positioned in between a fully pooled model, which imposes such common features, and a fully heterogeneous model, which allows for unrestricted nonlinearity. We introduce a second‐stage model linking the parameters that determine the timing of the switches between business cycle regimes to observable explanatory variables, thereby allowing for lead–lag relationships across panel members. We discuss representation, estimation by concentrated simulated maximum likelihood and inference. We illustrate our model using quarterly industrial production in 19 US manufacturing sectors, and document that there are subtle differences across sectors in leads and lags for switches between business cycle recessions and expansions. Copyright © 2005 John Wiley & Sons, Ltd.
Mechanisms of endothelial dysfunction with development of type 1 diabetes mellitus: Role of insulin and C‐peptide
Authors: Joshua Irving G. , Zhang Qin , Falcone Jeff C. , Bratcher Adrienne P. , Rodriguez Walter E. , Tyagi Suresh C.
Published: September 2005

Complications associated with insulin‐dependent diabetes mellitus (type‐1diabetes) primarily represent vascular dysfunction that has its origin in the endothelium. While many of the vascular changes are more accountable in the late stages of type‐1diabetes, changes that occur in the early or initial functional stages of this disease may precipitate these later complications. The early stages of type‐1diabetes are characterized by a diminished production of both insulin and C‐peptide with a significant hyperglycemia. During the last decade numerous speculations and theories have been developed to try to explain the mechanisms responsible for the selective changes in vascular reactivity and/or tone and the vascular permeability changes that characterize the development of type‐1diabetes. Much of this research has suggested that hyperglycemia and/or the lack of insulin may mediate the observed functional changes in both endothelial cells and vascular smooth muscle. Recent studies suggest several possible mechanisms that might be involved in the observed decreases in vascular nitric oxide (NO) availability with the development of type‐1 diabetes. In addition more recent studies have indicated a direct role for both endogenous insulin and C‐peptide in the amelioration of the observed endothelial dysfunction. These results suggest a synergistic action between insulin and C‐peptide that facilitates increase NO availability and may suggest new clinical treatment modalities for type‐1 diabetes mellitus. © 2005 Wiley‐Liss, Inc.
Adapter protein CRKII signaling is involved in the rat pancreatic acini response to reactive oxygen species
Authors: Andreolotti Alberto G. , Bragado María J. , Tapia José A. , Jensen Robert T. , Garcia‐Marin Luis J.
Published: September 2005

Recent studies demonstrate that reactive oxygen species (ROS) are important mediators of acute pancreatitis, whether induced experimentally or in necrotizing pancreatitis in humans; however, the cellular processes involved remain unclear. Adapter protein CrkII, plays a central role for convergence of cellular signals from different stimuli. Cholecystokinin (CCK), which induces pancreatitis, stimulates CrkII tyrosine phosphorylation and CrkII protein complexes, raising the possibility it can be important in the acinar cell responses to ROS. Therefore, our aim was to investigate whether CrkII signaling is involved in the biological response of rat pancreatic acini to H2O2 and the intracellular mediators implicated. Treatment of isolated rat pancreatic acini with H2O2 rapidly stimulates CrkII phosphorylation, measured as electrophoretic mobility shift and by using a phosphospecific antibody (pTyr221). Tyrosine kinase blocker B44 inhibits the higher phosphorylation state, demonstrating that it occurs mainly in tyrosine residues. H2O2‐induced CrkII phosphorylation is time‐ and concentration‐dependent, showing maximal effect with 3 mM H2O2 at 5 min. The intracellular pathways induced by H2O2 leading to CrkII tyrosine phosphorylation do not involve PKC, intracellular calcium, PI3‐K or the actin cytoskeleton integrity. ROS generation clearly promotes the formation of protein complex CrkII–PYK2. In conclusion, ROS clearly affect the key adapter protein CrkII signaling by two ways: stimulation of CkII phosphorylation and a functional consequence: formation of CrkII–protein complexes. Because of its central role in activating more distal pathways, CrkII might likely play an important role in the ability of ROS to induce pancreatic cellular injury and pancreatitis. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Indian hedgehog: Its roles and regulation in endochondral bone development
Authors: Lai Lick Pui , Mitchell Jane
Published: September 2005

Normal endochondral bone development requires the coordination of chondrocyte proliferation and differentiation. Indian hedgehog (Ihh) is a morphogen produced by chondrocytes in the early stage of terminal differentiation and plays several key roles in this process. Ihh regulates growth of adjacent proliferative chondrocytes and can also regulate the rate of differentiation of chondrocytes indirectly through its stimulation of parathyroid hormone‐related protein (PTHrP). In this review, we focus on recent studies that have identified new functions of Ihh and how Ihh itself is being regulated. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Direct activation of TGF‐β1 transcription by androgen and androgen receptor complex in Huh7 human hepatoma cells and its tumor in nude mice
Authors: Yoon Gyesoon , Kim Ji Yeon , Choi Yang Kyu , Won Young Suk , Lim In Kyoung
Published: September 2005

Importance of androgen for promotion of hepatocelullar carcinoma (HCC) has long been supported by clinical and experimental evidences. However, mechanisms involved in the carcinogenesis have not yet been fully elucidated. Moreover, unbalanced expression of TGF‐β1 during tumor progression results in prooncogenic rather than growth inhibition. To investigate the effect of androgen on transcriptional regulation of TGF‐β1, we isolated rat TGF‐β1 promoter, based on our previous report (GenBank AF249327), and examined regulation of its promoter activity by dihydrotestosterone in Huh7, LNCaP, and PC3 cells. Several putative transcription factor‐binding sites were found, but no TATA box. When the full‐length (−4784 to +68) and variously deleted promoter DNAs were evaluated, the promoter region spanning from −2732 to −1203 showed the highest activity towards dihydrotestosterone in a dose‐dependent manner in both Huh7 and PC3 cells with androgen receptor (AR) expression. Putative androgen response sequence half site (5′‐TGTCCT‐3′) was identified to be located within −1932 to −1927, proved by mutant (5′‐AGACCT‐3′) analysis and chromatin immunoprecipitation (ChIP) assay. AR mediated upregulation of TGF‐β1 expression was confirmed by HCC developed in nude mice with AR‐overexpressed Huh7‐cells. This work presents in vivo and in vitro evidences of activation of TGF‐β1 expression by androgen and AR, and implicates the modulation of hepatocarcinogenesis by AR through the regulation of TGF‐β1 expression. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Prenylation is not necessary for endogenous Ras activation in non‐malignant cells
Authors: Khwaja Arif , Dockrell Mark E.C. , Hendry Bruce M. , Sharpe Claire C.
Published: September 2005

Ras monomeric GTPases are pivotal to many core cellular processes such as proliferation and differentiation. The post‐translational prenylation of Ras with a farnesyl or a geranylgeranyl moiety is thought to be critical for its membrane binding and consequent signaling activity. Inhibitors of Ras prenylation have an anti‐proliferative effect in some Ras‐transformed cells. We present a study of the effects of prenylation inhibitors on endogenous, wild‐type Ras in three renal cell types, namely primary adult human renal fibroblasts, primary adult human mesangial cells, and a primate renal fibroblast cell line (Vero cells). We have previously demonstrated that Ras is necessary for normal proliferation in these cells. Here we show that Ras is farnesylated and not geranylgeranylated in all three cell types. Furthermore, inhibiting Ras farnesylation has no effect on cell proliferation or Ras activation. Although inhibiting geranylgeranylation in these cells does inhibit proliferation, this is through an Ras‐independent mechanism. Non‐prenylated Ras is able to localize to the plasma membrane, bind Raf when cells are stimulated by epidermal growth factor or platelet‐derived growth factor, and activate the Ras downstream effectors mitogen‐activated protein kinase and phosphotidylinositol 3‐kinase. We conclude that in wild‐type cells, endogenous Ras does not need to be prenylated to be active. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Regulation of microglial activities by glial cell line derived neurotrophic factor
Authors: Chang Yu‐Ping , Fang Kuan‐Ming , Lee Tsung‐I , Tzeng Shun‐Fen
Published: September 2005

Much attention has been paid to the ability of glial cell line‐derived neurotrophic factor (GDNF) to protect neurons from neurotoxic insults in the central nervous system (CNS). However, little is known about GDNF action on CNS glia that also can express GDNF receptor systems. In this study, we examined the effects of GDNF on primary rat microglia that function as resident macrophages in the CNS and as the source of proinflammatory mediators upon activation. We found that treatment of primary rat microglia with GDNF had no effect on the secretion of the proinflammatory cytokines, tumor necrosis factor‐α (TNF‐α) and interleukin‐1β (IL‐1β), but it increased the nitric oxide (NO) production to some extent. In addition, GDNF increased the enzymatic activity of superoxide dismutase (SOD), the gene expression of surface antigen intercellular adhesion molecule‐1 (ICAM‐1), the production of the integrin α5 subunit, and the phagocytotic capability in primary rat microglia. Furthermore, inhibition of mitogen‐activated protein kinase (Erk‐MAPK) in the mouse microglial cell line BV2 by U0126 indicated that the MAP kinase signaling pathway may be involved in the regulation of NO and integrin α5 production by GDNF. In vivo evidence also showed that amoeboid cells with integrin α5 or with ED1 immunoreactivity appeared in GDNF‐treated spinal cord tissues at the lesion site 1 week post spinal cord injury (SCI). Furthermore, inhibition of Erk‐MAPK in the mouse microglial cell line BV2 by U0126 indicated that the MAP kinase signaling pathway may be involved in the regulation of NO and integrin α5 production by GDNF. Taken together, our results indicate that GDNF has a positive regulatory effect on microglial activities, such as phagocytosis and the upregulation of adhesion molecules. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
C‐type natriuretic peptide enhances osteogenic protein‐1‐induced osteoblastic cell differentiation via Smad5 phosphorylation
Authors: Yeh Lee‐Chuan C. , Zavala Michelle C. , Lee John C.
Published: September 2005

In the present study, we examined the hypothesis that the C‐type natriuretic peptide (CNP) enhances osteogenic protein‐1 (OP‐1) action in stimulating osteoblastic cell differentiation in primary cultures of fetal rat calvaria cell (FRC). CNP enhanced synergistically the OP‐1‐induced Alkaline Phosphatase (AP) activity and mineralized bone nodule formation in a dose‐ and time‐dependent manner. To examine possible mechanism of the synergy between OP‐1 and CNP, the expression levels of key BMP receptors and signaling molecules were examined. Western blot analysis showed that BMPR‐IB and ‐II receptor protein expression was not affected by CNP alone, but was stimulated by OP‐1 alone. The combination of OP‐1 and CNP did not further increase their protein levels. The Runx2 protein expression level was not altered by CNP alone, but was elevated by OP‐1 alone, and was slightly reduced by the combination. The Smad5 protein expression level was slightly decreased by CNP alone, but was stimulated by OP‐1 alone, and was not further stimulated by the combination. Smad5 phosphorylation was not stimulated by CNP alone, but was stimulated significantly by OP‐1 alone. The combination of OP‐1 and CNP further stimulated the OP‐1‐induced Smad5 phosphorylation. Thus, one mechanism of the observed synergy between OP‐1 and CNP involves enhancement of the Smad5 phosphorylation. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Heterogeneity in the angiogenic response of a BT474 human breast cancer to a novel vascular endothelial growth factor‐receptor tyrosine kinase inhibitor: Assessment by voxel analysis of dynamic contrast‐enhanced MRI
Authors: Li Ka‐Loh , Wilmes Lisa J. , Henry Roland G. , Pallavicini Maria G. , Park John W. , Hu‐Lowe Dana D. , McShane Teresa M. , Shalinsky David R. , Fu Y‐J , Brasch Robert C. , Hylton Nola M.
Published: September 2005

Purpose

To investigate the heterogeneity in the angiogenic response of a human breast cancer xenograft to a novel vascular endothelial growth factor (VEGF)‐receptor tyrosine kinase inhibitor, AG‐013736, using dynamic contrast‐enhanced MR imaging (DCE‐MRI).

Materials and Methods

Changes in pharmacokinetic parameters in a seven‐day interval were compared between AG‐treated and control groups, using Gd‐DTPA and albumin‐(Gd‐DTPA)30. A voxel‐by‐voxel analysis was performed to produce parametric spatial pharmacokinetic parametric maps and histograms. Histogram segmentation was used to quantify the heterogeneity in tumor response to therapy, and compared with conventional descriptive measures of distribution in terms of their capacity to separate control from AG‐treated tumors.

Results

The albumin‐(Gd‐DTPA)30 endothelial transfer constant, Kps, showed changes with AG‐013736 treatment and tumor growth. The changes were highly heterogeneous for individual segments of the histogram with different Kps values, and the overall patterns in which the frequency distribution changed differed significantly between the two groups. A change in the number of voxels with Kps rangingfrom 0.03 to 0.14 mL/min/(100 mL tissue) was the most sensitive variable for separating control from AG‐treated tumors (P = 0.0008). Parametric maps of the kinetic parameters also showed spatial heterogeneity in tumor response to treatment. The Kps maps depicted rapid development of central necrosis as a result of AG‐013736 treatment. Maps of vp demonstrated a marked increase at peripheral regions of necrotic areas. Similar trends were noted in the Gd‐DTPA rate constant Ktrans distribution.

Conclusion

This study demonstrates the value of histogram analysis of maps of pharmacokinetic parameters for assessing heterogeneity in tumor response to antiangiogenic therapy. Changes in the number of voxels within certain segments of the Kps histogram were the most sensitive variable for separating control from AG‐treated tumors. J. Magn. Reson. Imaging 2005. © 2005 Wiley‐Liss, Inc.
Tractography‐based quantitation of diffusion tensor imaging parameters in white matter tracts of preterm newborns
Authors: Partridge Savannah C. , Mukherjee Pratik , Berman Jeffrey I. , Henry Roland G. , Miller Steven P. , Lu Ying , Glenn Orit A. , Ferriero Donna M. , Barkovich A. James , Vigneron Daniel B.
Published: September 2005

Purpose

To evaluate the feasibility of performing diffusion tensor tractography (DTT) to map and quantify the pyramidal white matter tracts of premature newborns.

Materials and Methods

Fourteen diffusion tensor MRI (DTI) examinations of nine premature newborns were evaluated. DTT was performed to segment bilateral pyramidal tracts, using a fiber‐tracking algorithm originating in the cerebral peduncle (CP) and filtering through the posterior limb of the internal capsule (PLIC) and precentral gyrus (PCG). Voxels containing the resulting tracts were then used for quantitation of DTI parameters along the tract. The DTT‐based tract measurements were compared with standard manually placed region‐of‐interest (ROI) measurements at four locations along the pyramidal tract, and the reproducibility of each technique was evaluated.

Results

DTT demonstrated improved reproducibility over manual ROI measurement for pyramidal tract quantitation and was less subject to intra‐operator variability (P < 0.0001, Fisher test for equal variance). In general, the anatomic locations and measurements obtained with the two techniques were in good agreement, although some systematic differences were identified in the PLIC and CP.

Conclusion

Fiber DTT is feasible in premature newborns, provides more reproducible tract measurements than manual ROI methods, and allows quantitation along the entire tract for more detailed DTI assessment of white matter maturation. J. Magn. Reson. Imaging 2005. © 2005 Wiley‐Liss, Inc.
Effects of alfalfa protein concentrate on spatial learning and memory in weaned rats
Authors: García‐López Pedro M , Alfaro Noe , García‐Estrada Joaquín , Bañuelos‐Pineda Jacinto , Gurrola‐Díaz Carmen M , García‐López Jesús S , Rodiles Carmen Gómez , Ruíz‐López Mario A , Garzón‐de la Mora Pedro
Published: September 2005

Alfalfa has been used as animal feedstuff and nowadays as a human dietary supplement in undernourished populations. Therefore, we considered whether a 65 °C prepared unfractionated alfalfa protein concentrate (UAPC) could be capable of supporting the normal body growth of weaned rats as well as their spatial learning, memory and astroglial organization. Rats were fed isocaloric (1.8 kJ g−1) and isoproteic (100 g kg−1) diets for 28 days containing UAPC or casein as their protein source. Thereafter, animals were submitted to a Morris water maze test (MWM) followed by an evaluation of memory retention. At the end of the spatial learning tests, the cerebral cortex, hippocampus and hypothalamus astrocyte population was morphologically and immunohistochemically analyzed. UAPC had two limiting essential amino acids that seem to have retarded rates of growth and caused temporary learning and memory alterations. The UAPC diet induced a transitory memory loss as well as a recoverable memory retention delay after returning to a commercial ration. The astrocyte cell number was decreased in the parietal cortex and arcuate nucleus but not in the hippocampus; however, the latter showed a minor reduction in their cell density. UAPC did not adequately support the development of weaned rats, and decreased the number of astrocytes in the cerebral cortex and hypothalamus. Copyright © 2005 Society of Chemical Industry
Negatively charged sol‐gel column with stable electroosmotic flow for online preconcentration of zwitterionic biomolecules in capillary electromigration separations
Authors: Li Wen , Fries David , Malik Abdul
Published: September 2005

A negatively charged sol‐gel coating was developed for on‐line preconcentration of zwitterionic biomolecules in capillary electrophoresis (CE), using asparagine and myoglobin as representative zwitterionic bioanalytes. The sol‐gel coating was created by using a solution containing three precursors: mercaptopropyltrimethoxysilane (MPTMS), tetramethoxysilane (TMOS), and n‐octadecyltriethoxysilane (C18‐TEOS). The resulting sol‐gel coating contained chemically bonded mercaptopropyl functional groups that were further oxidized by hydrogen peroxide to the corresponding sulfonic acid moieties. Such a surface‐bonded sol‐gel coating can carry a negative charge over a wide range of pH due to the presence of deprotonated sulfonic acid groups. Under favorable pH conditions, the negatively charged sol‐gel coating can facilitate the extraction of positively charged analytes from a zwitterionic sample through electrostatic interaction. This principle was employed to extract myoglobin and asparagine by passing aqueous samples of these zwitterionic analytes through a negatively charged sol‐gel column. The extracted analytes were then desorbed and focused via local pH change and stacking. The local pH change was accomplished by passing a buffer solution with a pH above the solute pI value, while a dynamic pH junction between the sample solution and the background electrolyte was utilized to facilitate solute focusing. The sorption/desorption phenomena could, perhaps, also be explained on the basis of ion‐exchange and local pH junction effects. On‐line preconcentration and analysis results obtained on sulfonated sol‐gel columns were compared with those obtained on an uncoated fused silica capillary of identical dimensions using conventional sample injections. Using UV detection, the presented sample preconcentration technique provided a sensitivity enhancement factor (SEF) on the order of 3×103 for myoglobin, and 7×103 for asparagine.
Coherent array of non-spreading atomic wave packets in
absorptive optical potentials
Authors: Petropavlovsky S V , Yakovlev V P , Efremov M A , Fedorov M V , Schleich W P
Published: September 2005

The results on non-spreading Michelangelo wave packets
[7,8] are generalized to the case of a
semi-open two-level system when some fraction of atoms falls back
to the lower state due to spontaneous transitions. The proposed
approach is based on the solution of the Generalized Optical Bloch
Equations for the atomic density matrix. The spatial features of
arising non-spreading wave packets as well as the atomic momentum
distribution are compared with the case of an open two-level
system.
Coherent backscattering of light from ultracold and optically dense atomic ensembles
Authors: Kupriyanov D V , Sokolov I M , Sukenik C I , Havey M D
Published: September 2005

We review experimental and theoretical studies of coherent backscattering of near resonant radiation from an ultracold atomic gas in the weak localization regime. Recent accomplishments in high resolution spectroscopy of atomic ensembles based on the coherent backscattering process are discussed. We also propose several new experimental schemes for time-dependent spectroscopy as applied to multiple scattering in the regime of weak localization.
Dynamic three‐dimensional undersampled data reconstruction employing temporal registration
Authors: Irarrazaval Pablo , Boubertakh Redha , Razavi Reza , Hill Derek
Published: September 2005

Dynamic 3D imaging is needed for many applications such as imaging of the heart, joints, and abdomen. For these, the contrast and resolution that magnetic resonance imaging (MRI) offers are desirable. Unfortunately, the long acquisition time of MRI limits its application. Several techniques have been proposed to shorten the scan time by undersampling the k‐space. To recover the missing data they make assumptions about the object's motion, restricting it in space, spatial frequency, temporal frequency, or a combination of space and temporal frequency. These assumptions limit the applicability of each technique. In this work we propose a reconstruction technique based on a weaker complementary assumption that restricts the motion in time. The technique exploits the redundancy of information in the object domain by predicting time frames from frames where there is little motion. The proposed method is well suited for several applications, in particular for cardiac imaging, considering that the heart remains relatively still during an important fraction of the cardiac cycle, or joint imaging where the motion can easily be controlled. This paper presents the new technique and the results of applying it to knee and cardiac imaging. The results show that the new technique can effectively reconstruct dynamic images acquired with an undersampling factor of 5. The resulting images suffer from little temporal and spatial blurring, significantly better than a sliding window reconstruction. An important attraction of the technique is that it combines reconstruction and registration, thus providing not only the 3D images but also its motion quantification. The method can be adapted to non‐Cartesian k‐space trajectories and nonuniform undersampling patterns. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Role of a FMRFamide‐like family of neuropeptides in the pharyngeal nervous system of Caenorhabditis elegans
Authors: Papaioannou Sylvana , Marsden David , Franks Christopher J. , Walker Robert J. , Holden‐Dye Lindy
Published: September 2005

The nervous system of C. elegans has a remarkable abundance of flp genes encoding FMRFamide‐like (FLP) neuropeptides. To provide insight into the physiological relevance of this neuropeptide diversity, we have tested more than 30 FLPs (encoded by 23 flps) for bioactivity on C. elegans pharynx. Eleven flp genes encode peptides that inhibit pharyngeal activity, while eight flp genes encode peptides that are excitatory. Three potent peptides (inhibitory, FLP‐13A, APEASPFIRFamide; excitatory, FLP‐17A, KSAFVRFamide; excitatory, FLP‐17B, KSQYIRFamide) are encoded by flp genes, which, according to reporter gene constructs, are expressed in pharyngeal motoneurons. Thus, they may act through receptors localized on the pharyngeal muscle. The two other potent peptides, FLP‐8 (excitatory AF1, KNEFIRFamide,) and FLP‐11A (inhibitory, AMRNALVRFamide), appear to be expressed in extrapharyngeal neurons and are therefore likely to act either indirectly or as neurohormones. Intriguingly, a single neuron can express peptides that have potent but opposing biological activity in the pharynx. Only five flp genes encode neuropeptides that have no observable effect on the pharynx, but none of these have shown reporter gene expression in the pharyngeal nervous system. To examine the roles of multiple peptides produced from single precursors, a comparison was made between the bioactivity of different neuropeptides for five flp genes (flp‐3, flp‐13, flp‐14, flp‐17, and flp‐18). For all but one gene (flp‐14), the effects of peptides encoded by the same gene were similar. Overall, this study demonstrates the impressive neurochemical complexity of the simple circuit that regulates feeding in the nematode, C. elegans. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2005
Defining the competencies of those conducting pharmacovigilance
Authors: Edwards Brian , Tilson Hugh H. , West Suzanne L.
Published: September 2005

Purpose

The absence of agreed competencies in pharmacovigilance and patient risk management is a key factor hindering the development of training and a curriculum in these interrelated disciplines. If competencies were to be developed, they could be tailored to the different roles and responsibilities of the various staff involved.

Proposal

We describe a simple theoretical model of functional and behavioural competencies that is based on an organisation with three levels of staff: evidence collectors and gatherers, evidence processors and distillers, and decision makers.

Conclusions

To stimulate discussion about how to enhance the progress already being made in pharmacovigilance and patient risk management, we have proposed functional and behavioural competencies for pharmacovigilance as a way of identifying and measuring scientific and personal skills pertinent to pharmacovigilance. Competencies should, we believe, be agreed and adopted by all those seeking to improve pharmacovigilance. We invite discussion of these proposals. Copyright © 2005 John Wiley & Sons, Ltd.