bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcription factor Egr1 acts as an upstream regulator of β‐catenin signalling through up‐regulation of TCF4 and p300 expression during trans‐differentiation of endometrial carcinoma cells
Authors: Saegusa M , Hashimura M , Kuwata T , Hamano M , Watanabe J , Kawaguchi M , Okayasu I
Published: July 2008

The β‐catenin/TCF4/p300 pathway is involved in early signalling for trans‐differentiation towards the morular phenotype of endometrial carcinoma cells, but little is known about the upstream regulators. Here we show that transcription factor early growth response 1 (Egr1) acts as an initial mediator through up‐regulating the expression of TCF4 and p300. In an endometrial carcinoma cell line with abundant oestrogen receptor α, Egr1 expression at both mRNA and protein levels was significantly increased by serum and 17β‐oestradiol stimuli. Serum‐stimulated cells also showed increased expression of TCF4 and p300, while inhibition of Egr1 by specific siRNAs resulted in decreased expression. Transfection of Egr1 led to transactivation of TCF4 as well as p300 genes, through specific binding to a promoter region, and thus in turn resulted in nuclear accumulation of β‐catenin mediated by the up‐regulating TCF4. The overexpression also caused inhibition of β‐catenin/TCF4/p300‐mediated transcription, probably through sequestration of p300. Egr1 promoter activity was increased by serum but not 17β‐oestradiol, in contrast to the marked repression associated with TCF4, p300, and Egr1 itself, indicating that the regulation involves several feedback loops. In clinical samples, cells immunopositive for nuclear Egr1, as well as β‐catenin and TCF4, were found to be sporadically distributed in glandular components of endometrial carcinoma with morules. A significant positive correlation between nuclear β‐catenin and TCF4 was observed, but no such link was evident for Egr1, probably due to the existence of negative feedback regulation. Together, these data indicate that Egr1 may participate in modulation of the β‐catenin/TCF4/p300 signalling pathway as an initial event during trans‐differentiation of endometrial carcinoma cells, through its impact on several signalling networks. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Oestrogen receptor gene (ESR1) amplification is frequent in endometrial carcinoma and its precursor lesions
Authors: Lebeau A , Grob TJ , Holst F , Seyedi‐Fazlollahi N , Moch H , Terracciano Luigi , Turzynski A , Choschzick M , Sauter G , Simon R
Published: July 2008

Oestrogen receptor alpha (ER) plays a critical, diverse and not fully understood role in endometrial carcinoma. Most endometrial carcinomas express ER and some of these tumours respond favourably to anti‐oestrogen therapy. On the other hand, tamoxifen therapy constitutes a major risk factor for endometrial carcinoma development. Amplification of the ESR1 gene encoding ER was recently shown to constitute a mechanism for ER over‐expression in breast carcinoma. This study was designed to determine the potential role of ESR1 amplifications in endometrial carcinoma. Tissue microarrays of 368 endometrial carcinomas and large sections of 43 cases of endometrial hyperplasia were analysed for ESR1 gene amplification and ER protein expression by means of fluorescence in situ hybridization (FISH) and immunohistochemistry. FISH revealed ESR1 amplification in 40/176 (23%) cancers, 6/19 (32%) atypical complex hyperplasias, 3/10 (30%) complex hyperplasias without atypia and 2/14 (14%) simple hyperplasias without atypia. Strong ER protein expression was significantly linked to ESR1 amplification in endometrial carcinoma (p = 0.0036). These data indicate that ESR1 amplification might be one mechanism for ER over‐expression in endometrial carcinoma, and suggest an early role for ESR1 amplification in the development of a significant fraction of endometrial carcinoma. Given the predictive role of ESR1 amplification for tamoxifen response in breast carcinoma, it will be interesting to investigate the response of ESR1‐amplified endometrial cancers to anti‐oestrogenic drugs. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Minimal disease monitoring by QRT–PCR: guidelines for identification and systematic validation of molecular markers prior to evaluation in prospective clinical trials
Authors: Viprey VF , Lastowska MA , Corrias MV , Swerts K , Jackson MS , Burchill SA
Published: July 2008

Real‐time RT–PCR (QRT–PCR) is a sensitive method for the detection of minimal disease (MD) and may improve monitoring of disease status and stratification of patients for therapy. Where tumour‐specific mRNAs have not been identified, the selection of which target(s) is(are) optimal for the detection of MD remains a challenge. This reflects the heterogeneity of tumour cells, the stability of mRNAs and low‐level of transcription in cells of the normal haemopoietic compartments. The aim of this study was to establish for the first time guidelines for the systematic prioritization of potential markers of MD detected by QRT–PCR prior to evaluation in multicentre prospective clinical outcome studies. We combined microarray analysis, ESTs gene expression profiles, improved probe‐sets sequence annotation, and previously described standard operating procedures for QRT–PCR analysis to identify and prioritize potential markers of MD. Using this methodology, we identified 49 potential markers of MD in neuroblastoma (NB), of which 11 were associated with neuronal function. We found that, in addition to TH, Phox2B and DCX mRNA may be useful targets for the detection of MD in children with NB. This same strategy could be exploited to select MD markers of other solid tumours from the large number of potential targets identified by microarray gene expression profiles. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Refinement of breast cancer classification by molecular characterization of histological special types
Authors: Weigelt B , Horlings HM , Kreike B , Hayes MM , Hauptmann M , Wessels LFA , de Jong D , Van de Vijver MJ , Veer LJ Van't , Peterse JL
Published: July 2008

Most invasive breast cancers are classified as invasive ductal carcinoma not otherwise specified (IDC NOS), whereas about 25% are defined as histological ‘special types’. These special‐type breast cancers are categorized into at least 17 discrete pathological entities; however, whether these also constitute discrete molecular entities remains to be determined. Current therapy decision‐making is increasingly governed by the molecular classification of breast cancer (luminal, basal‐like, HER2+). The molecular classification is derived from mainly IDC NOS and it is unknown whether this classification applies to all histological subtypes. We aimed to refine the breast cancer classification systems by analysing a series of 11 histological special types [invasive lobular carcinoma (ILC), tubular, mucinous A, mucinous B, neuroendocrine, apocrine, IDC with osteoclastic giant cells, micropapillary, adenoid cystic, metaplastic, and medullary carcinoma] using immunohistochemistry and genome‐wide gene expression profiling. Hierarchical clustering analysis confirmed that some histological special types constitute discrete entities, such as micropapillary carcinoma, but also revealed that others, including tubular and lobular carcinoma, are very similar at the transcriptome level. When classified by expression profiling, IDC NOS and ILC contain all molecular breast cancer types (ie luminal, basal‐like, HER2+), whereas histological special‐type cancers, apart from apocrine carcinoma, are homogeneous and only belong to one molecular subtype. Our analysis also revealed that some special types associated with a good prognosis, such as medullary and adenoid cystic carcinomas, display a poor prognosis basal‐like transcriptome, providing strong circumstantial evidence that basal‐like cancers constitute a heterogeneous group. Taken together, our results imply that the correct classification of breast cancers of special histological type will allow a more accurate prognostication of breast cancer patients and facilitate the identification of optimal therapeutic strategies. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Amelioration of the premature ageing‐like features of Fgf‐23 knockout mice by genetically restoring the systemic actions of FGF‐23
Authors: DeLuca S , Sitara D , Kang K , Marsell R , Jonsson K , Taguchi T , Erben RG , Razzaque MS , Lanske B
Published: July 2008

Genetic ablation of fibroblast growth factor 23 from mice (Fgf‐23−/−) results in a short lifespan with numerous abnormal biochemical and morphological features. Such features include kyphosis, hypogonadism and associated infertility, osteopenia, pulmonary emphysema, severe vascular and soft tissue calcifications, and generalized atrophy of various tissues. To determine whether these widespread anomalies in Fgf‐23−/− mice can be ameliorated by genetically restoring the systemic actions of FGF‐23, we generated Fgf‐23−/− mice expressing the human FGF‐23 transgene in osteoblasts under the control of the 2.3 kb α1(I) collagen promoter (Fgf‐23−/− /hFGF‐23‐Tg double mutants). This novel mouse model is completely void of all endogenous Fgf‐23 activity, but produces human FGF‐23 in bone cells that is subsequently released into the circulation. Our results suggest that lack of Fgf‐23 activities results in extensive premature ageing‐like features and early mortality of Fgf‐23−/− mice, while restoring the systemic effects of FGF‐23 significantly ameliorates these phenotypes, with the resultant effect being improved growth, restored fertility, and significantly prolonged survival of double mutants. With regard to their serum biochemistry, double mutants reversed the severe hyperphosphataemia, hypercalcaemia, and hypervitaminosis D found in Fgf‐23−/− littermates; rather, double mutants show hypophosphataemia and normal serum 1,25‐dihydroxyvitamin D3 levels similar to pure FGF‐23 Tg mice. These changes were associated with reduced renal expression of NaPi2a and 1α‐hydroxylase, compared to Fgf‐23−/− mice. FGF‐23 acts to prevent widespread abnormal features by acting systemically to regulate phosphate homeostasis and vitamin D metabolism. This novel mouse model provides us with an in vivo tool to study the systemic effects of FGF‐23 in regulating mineral ion metabolism and preventing multiple abnormal phenotypes without the interference of native Fgf‐23. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Surface changes in polyhydroxyalkanoate films during biodegradation and biofouling
Authors: Woolnough Catherine A , Charlton Tim , Yee Lachlan H , Sarris Maria , Foster L John R
Published: July 2008

BACKGROUND: Despite the recognition that microbial biofilms play a role in environmental degradation of bioplastics, few studies investigate the relationship between bioplastic biodegradation and microbial colonisation. We have developed protocols based on a combination of confocal laser scanning microscopy and contact angle goniometry to qualitatively and quantitatively map surface changes due to biofilm formation and biopolymer degradation of solvent cast poly(3‐hydroxyalkanoate) films in an accelerated in vitro biodegradation system.

RESULTS: A significant regression relationship between biofilm formation and polymer biodegradation (R2 = 0.96) was primarily conducted by cells loosely attached to the film surfaces (R2 = 0.95), rather than the strongly attached biofilm (R2 = 0.78). During biodegradation the surface rugosity of poly(3‐hydroxybutyrate) and poly[(3‐hydroxybutyrate)‐co‐(3‐hydroxyvalerate)] increased by factors of 1.5 and 1.76, respectively. In contrast, poly(3‐hydroxyoctanoate) films showed little microbial attachment, negligible weight loss and insignificant changes in surface rugosity.

CONCLUSION: A statistically significant link is established between polymer weight loss and biofilm formation. Our results suggest that this degradation is primarily conducted by cells loosely attached to the polymer rather than those strongly attached. Biofilm formation and its type are dependent upon numerous factors; the flat undifferentiated biofilms observed in this study produce a gradual increase in surface rugosity, observed as an increase in waviness. Copyright © 2008 Society of Chemical Industry
An investigation into hot‐spots in two large grid‐connected PV plants
Authors: Muñoz J. , Lorenzo E. , Martínez‐Moreno F. , Marroyo L. , García M.
Published: July 2008

This paper details an investigation into the appearance of hot‐spots in two large grid‐connected photovoltaics (PV) plants, which were detected after the visual inspection of trackers whose energy output was decreasing at anomalous rate. Detected hot‐spots appeared not only in the solar cells but also in resistive solder bonds (RSB) between cells and contact ribbons. Both types cause similar irreversible damage to the PV modules, but the latter are the main responsible for the detected decrease in energy output, which was confirmed in an experimental testing campaign. The results of this investigation, for example, how hot‐spots were detected or their impact on the output power of PV modules, may be of interest for the routine maintenance of large grid‐connected PV plants. Copyright © 2008 John Wiley & Sons, Ltd.
Effect of Nano‐Copper Oxide and Copper Chromite on the Thermal Decomposition of Ammonium Perchlorate
Authors: Patil Prajakta R. , Krishnamurthy V. N. , Joshi Satyawati S.
Published: July 2008

The catalytic effect on the thermal decomposition behavior of ammonium perchlorate (AP) of p‐type nano‐CuO and CuCr2O4 synthesized by an electrochemical method has been investigated using differential scanning calorimetry as a function of catalyst concentration. The nano‐copper chromite (CuCr2O4) showed best catalytic effects as compared to nano‐cupric oxide (CuO) in lowering the high temperature decomposition by 118 °C at 2 wt.‐%. High heat releases of 5.430 and 3.921 kJ g−1 were observed in the presence of nano‐CuO and CuCr2O4, respectively. The kinetic parameters were evaluated using the Kissinger method. The decrease in the activation energy and the increase in the rate constant for both the oxides confirmed the enhancement in catalytic activity of AP. A mechanism based on an electron transfer process has also been proposed for AP in the presence of nano‐metal oxides.
Granular formulation of Fusarium oxysporum for biological control of faba bean and tomato Orobanche
Authors: Nemat Alla Mamdouh M , Shabana Yasser M , Serag Mamdouh M , Hassan Nemat M , El‐Hawary Mohamed M
Published: July 2008

BACKGROUND: Orobanche spp. represent a serious threat to a wide range of crops. They are difficult targets for herbicides, and biological control could provide a possible solution. This work therefore aimed to formulate mycoherbicides of Fusarium with adequate shelf life and virulence against Orobanche but safe to faba bean and tomato.

RESULTS: Only two isolates of Fusarium oxysporum Schlecht. (Foxy I and Foxy II) obtained from diseased Orobanche shoots were found to be pathogenic to Orobanche crenata Forsk. and Orobanche ramosa L. Conidial suspension of both isolates significantly decreased germination, attachments and tubercles of Orobanche. Microconidia and chlamydospores of both isolates were formulated as mycoherbicides encapsulated in a wheat flour–kaolin matrix (four different formulations). All formulations greatly diminished Orobanche emerged shoots, total shoot number, shoot height, attachment of emerged shoots, the germinated seeds that succeeded in emerging above the soil surface and dry weight. Meanwhile, disease incidence and disease severity of emerged shoots were enhanced. The shelf life was adequate, particularly for coarse, freshly prepared, low‐temperature‐stored, microconidia‐rich formulations. The induced growth reduction of Orobanche‐infected host plants seemed to be nullified by formulations, particularly at the highest dose.

CONCLUSION: These formulations seemed to destroy Orobanche but appeared harmless to host plants. Hence, they could be efficiently used as mycoherbicides for biological control of Orobanche in faba bean and tomato. Copyright © 2008 Society of Chemical Industry
Current approaches to drug treatment in rheumatoid arthritis
Authors: Young Adam
Published: July 2008

Drug treatments for RA include a wide choice of analgesics, anti‐inflammatories and DMARDs, used alone and in combination. Here, our Drug review describes the available drug therapies and their place in treatment, followed by sources of further information in Resources. Copyright © 2008 Wiley Interface Ltd
Microstructure and magnetic properties of FePt–SiO2 perpendicular recording media
Authors: Hu J. F. , Chen J. S. , Lim B. C. , Liu B.
Published: July 2008

FePt–SiO2 films with different volume percentage (0–20%) of SiO2 were prepared by a co‐sputtering process at a substrate temperature of 350 °C. The microstructure and magnetic properties of the composite films were investigated. Inhomogeneous SiO2 segregation in the composite films was observed. It was found that the SiO2 segregation depended on the sputter power used for FePt and SiO2 deposition. For low sputter power, most of the SiO2 was located at the film surface. As the sputter power increased, a two‐layer film composed of a continuous FePt layer on the bottom and a FePt–SiO2 composite layer on the top was observed. The possible reasons for SiO2 accumulation on the surface and the two‐layer film growth are proposed. The results suggested that the SiO2 segregation at high temperature was very sensitive to the dynamic film growth process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The influence of substrate on the magnetic properties of MnZn ferrite thin film fabricated by alternate sputtering
Authors: Wang Lanxi , Bai Jianmin , Li Zhenghua , Cao Jiangwei , Wei Fulin , Yang Zheng
Published: July 2008

Mn0.5Zn0.5Fe2O4 film which has the highest saturation magnetization among Mn1–x Znx Fe2O4 thin films was prepared by the alternate rf sputtering method from two targets with compositions of MnFe2O4 and ZnFe2O4, respectively. The films were deposited on single‐crystal Si(100), MgO(100) and SiO2/Si(100) substrates. The as‐deposited films were amorphous, and after annealing in a vacuum furnace at 550 °C, polycrystalline MnZn ferrite films with residual amorphous matrix were obtained. The coercivity of all films is low, and the film on the MgO(100) substrate shows a coercivity as low as 27 Oe. The grain size of all films is about 20 nm and is less than the ferromagnetic exchange length (160 nm), so magnetic anisotropies are averaged to lower effective values. Furthermore, the negative magnetostriction constant of crystalline MnZn ferrite and the positive magnetostriction constant of amorphous Fe‐based matrix will cancel out and may lead to a low or vanishing saturation magnetostriction constant. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local structure and magnetic properties of mechanically alloyed Fe60Mn40
Authors: Yang Dong‐Seok , Kim Nayoung , Yoo Yong‐Goo , Yu Seong‐Cho
Published: July 2008

Fe60Mn40 alloys were fabricated by mechanical alloying process for 1 h, 4 h, 6 h, 12 h and 24 h, respectively. The structural evolution during the milling process has been investigated by X‐ray diffraction and extended X‐ray absorption fine structure (EXAFS). The structural investigation shows that the alloying was activated in 6 h and progressed significantly in 24 h. Also, it showed that the BCC characteristics of the mixed powder remained after 6 h milling but disappeared after 12 h milling. It has been shown that variations of magnetic properties were closely related to the local structural evolution. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical properties of yttrium‐doped Zn and Ni–Zn ferrites
Authors: Stojanović Goran , Srdić Vladimir , Maletin Marija
Published: July 2008

Three types of zinc ferrite samples ZnFe2–x Yx O4 (x = 0, 0.3 and 0.6) and two of nickel–zinc ferrites Ni0.5Zn0.5Fe2–x Yx O4 (x = 0 and 0.3) were prepared by a low‐temperature chemical co‐precipitation method in order to examine the influence of yttrium ions on the electrical properties of these nanostructured ferrites. Plots for the real and imaginary parts of the permittivity, tangent loss and resistivity of these samples were obtained as a function of frequency using capacitance measurements of an impedance analyser in the frequency range from 100 Hz to 40 MHz at room temperature. It is observed that with appropriate addition of yttrium ions, dielectric constant and dielectric loss tangent can be decreased and resistivity increased. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local structure of Mn dopants in CuAlS2 and CuGaS2
Authors: Zalewski W. , Bacewicz R. , Antonowicz J. , Schorr S. , Streeck C. , Korzun B.
Published: July 2008

The local structure around Mn atoms in Mn‐doped CuAlS2 and CuGaS2 chalcopyrites is investigated using the X‐ray absorption fine structure method. Extended X‐ray absorption fine structure spectroscopy (EXAFS) and X‐ray absorption near‐edge spectroscopy measurements at the Mn K‐edge indicate that Mn substitutes on the cationic atoms sites. In the CuAlS2 structure Mn is located at both Cu and Al sites, with a preference for the Cu sites for higher Mn concentrations. Discrimination between Mn at two cationic sites is impossible for CuGaS2:Mn using EXAFS due to almost identical photoelectron scattering amplitudes and phases for Cu and Ga atoms. The nearest‐neighbour Mn–S distance for all studied compositions is close to 2.41 Å which is a typical value for the Mn–S tetrahedral bond length. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear and nonlinear magneto‐optical response of ultrathin Co/Au/Mo and Co/Mo films grown on sapphire substrates
Authors: Stupakiewicz A. , Kirilyuk A. , Maziewski A. , Rasing Th. , Wawro A. , Baczewski L. T.
Published: July 2008

We report studies of the linear and nonlinear magneto‐optical properties of epitaxial ultrathin Co films grown on sapphire substrates covered with Mo or Mo/Au buffers. Changes of the crystallographic symmetry and magnetization of buried interfaces were deduced from the magneto‐optical Kerr effect hysteresis loops and magnetization‐induced second‐harmonic generation (MSHG). Depending on the buffer, two‐fold (for Mo buffer) or six‐fold (for Mo/Au buffer) symmetries were observed in both inplane magnetic anisotropy and MSHG intensity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation of thin ferrite films on silicon using RF sputtering
Authors: Koblischka M. R. , Kirsch M. , Brust M. , Koblischka‐Veneva A. , Hartmann U.
Published: July 2008

Thin‐films of Nix Zn1–x Fe2O4 [(Ni,Zn)‐ferrite] are grown by means of RF sputtering on Si(100) and (111) substrates, corresponding to the orientation of Si cantilevers for AFM/MFM measurements. We find that the ferrite can be sputtered directly onto the Si surfaces, but an additional annealing step is required to obtain a purely polycrystalline, soft magnetic film. The microstructure of the films is investigated employing transmission electron microscopy, electron backscatter diffraction and magnetic force microscopy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Zn–In–O based thin‐film transistors: Compositional dependence
Authors: Itagaki N. , Iwasaki T. , Kumomi H. , Den T. , Nomura K. , Kamiya T. , Hosono H.
Published: July 2008

The compositional dependence of sputter‐deposited Zn–In–O (ZIO) film properties and the TFT performance were studied by means of a combinatorial technique. Both the characteristics of ZIO‐TFTs and the ZIO film properties are very sensitive to the Zn:In ratio. The best TFT performances are obtained at Zn:In ∼60:40 at%, where the saturation mobility (μsat), subthreshold swing (S.S.), on–off current ratio (Ion/Ioff), and threshold voltage (Vth) are 26.5 cm2/V s, 0.24 V/dec., 1010, and +2 V, respectively. The TFT characteristics peak at this compositional ratio. Specifically, μsat, Ion/Ioff and Vth reach maximum, while S.S. reaches minimum at this ratio. The air stability of ZIO‐TFTs was also examined for active channel layers with different Zn:In ratios, which clarified that the TFTs with high stability are obtained around the same composition ratio where the best characteristics are obtained. It was confirmed by X‐ray diffraction and transmission electron microscopy that the ZIO films with this composition ratio have amorphous structure. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lithium mobility in complexes Li[Cn]1 (n = 5−21): PES analysis in different stationary points
Authors: Balashov A. M. , Ermilov A. Yu. , Scherbinin A. V.
Published: July 2008

The equilibrium geometries of the cylinder‐like lithium hydrocarbon complexes Li[Cn]1 (n = 7–12) are calculated within Density Functional Theory(DFT) with PBE0 exchange‐correlation potential. The 6‐31 G* basis was set on carbon and lithium atoms while STO‐3G one was chosen for hydrogens. The tendencies found for complexes with n = 7–12 gets broken and transforms to asymptotic behavior in range of n > 13. The large complexes possess the structure where lithium is placed at the carbon hexagon center area and close to C2v symmetry. Opposite, for n = 5–6 lithium is placed on the high symmetry axis of initial hydrocarbon. Several stationary points of complexes with n = 8–21, defined by lithium location under the hexagon center (1), under the CC bond center (2) and at the hydrocarbon skeleton center (3) were found. The migration barriers between stationary points (1)–(3) were estimated. The type (3) structures are distinctly higher of energy than (1) and (2), at that the difference is increased according to growing of n. The complexes with n < 13 are characterized by usual charge transfer from metal to hydrocarbon skeleton, for n ≥ 13 the molecular‐like solution is occurred. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Simultaneous σ‐hole and hydrogen bonding by sulfur‐ and selenium‐containing heterocycles
Authors: Murray Jane S. , Lane Pat , Politzer Peter
Published: July 2008

When a Group V, VI, or VII atom forms a covalent bond, its bonding orbital has a deficiency of electronic charge in its outer (noninvolved) lobe. This is called a σ‐hole. If the atom is sufficiently polarizable, the σ‐hole may have a positive electrostatic potential which can interact with a nucleophilic site in its proximity to form a noncovalent bond. In this article, we show computationally, for a series of sulfur and selenium heterocycles, how the two σ‐holes on each S or Se atom are affected by changes in the molecular framework and substituents. It is possible to selectively design σ‐holes of appropriate strength and orientation for specific purposes, e.g. drug‐receptor interactions or crystal engineering. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Shifts of the hydrogen atom in a cylindrical cavity
Authors: Yurenev P. V. , Scherbinin A. V. , Pupyshev V. I.
Published: July 2008

Hydrogen atom in a cylindrical cavity is the simplest model for describing electronic states of the atom encapsulated into the nanotube. In the present work, simple analytical estimates for the electronic energy change under longitudinal and transversal shifts of the nucleus are made, using the first‐order perturbation theory with the radius of the cavity as a perturbation parameter. Predicted signature of the electronic energy for the variety of atomic states agrees in essential details with the direct numerical estimations by finite difference and collocation procedures. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
PO → Si intramolecular coordination in the derivatives of 1,4‐phosphasilacyclohexane 1‐oxides
Authors: Shainyan Bagrat A. , Lazareva Natalia F.
Published: July 2008

The chair and boat conformers for a series of derivatives of 1,4‐phosphasilacyclohexane 1‐oxides have been calculated at the B3LYP/6‐311+G** level of theory in the gas phase and taking into account the effect of solvent polarity using the IEF‐PCM model. The stability of the boat conformers containing pentacoordinate silicon due to formation of the PO→Si intramolecular coordination bond depends on the environment of the phosphorus atom and polarity of the solvent, and the strength of the transannular bond depends also on the nature of the substituents at the silicon atom. The highly polar boat conformers are strongly stabilized in the DMSO solution. NBO analysis showed the importance of the σ(CSi)→σ*(H3CN) hyperconjugative interaction in the two H3CNCSi fragments of the ring favoring the formation of the pentacoordinate silicon atom. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Temperature effects on polaron stability in polyacetylene
Authors: da Cunha Wiliam Ferreira , de Oliveira Neto Pedro Henrique , Gargano Ricardo , Magela e Silva Geraldo
Published: July 2008

In this work, we investigate the influence of the temperature imposed to a system initially composed of a free polaron moving through a trans‐polyacetylene chain. Our approach uses a version of the Su, Schrerieffer, and Heeger model where we included temperature effects on the lattice in a phenomenological way. We observed that greater temperatures lead nonlinear structure such as the polaron to become instable and disappear. Therefore, temperature is an important factor when it comes to describe the life time of these structures. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
MP2 study on decomposition of nitrous oxide on the Ga‐ZSM‐5
Authors: Solkan V. N. , Zhidomirov G. M.
Published: July 2008

The reaction mechanism for nitrous oxide decomposition has been studied on gallium site in Ga‐ZSM‐5 using the MP2/6‐31+G(d) method. The active centers were taken to be mononuclear [Ga]+, [GaO]+, and [GaO2]+ and the surrounding portion of the zeolite was represented by a 3T cluster, namely [AlSi2O4H8]−. The first elementary step of N2O decomposition involves the formation of [GaO]+ and the release of N2. The metal‐oxo species produced in this step then reacts with N2O again, to release N2 and form [GaO2]+. The calculated activation energies at MP2 level for N2O dissociation on Ga‐ZSM‐5 and GaO‐ZSM‐5 are 15.7 and 26.5 kcal/mol at 298 K, respectively. The third elementary step of N2O decomposition on GaO2‐ZSM‐5 involves the formation of [GaO3]+ and the release of N2. The calculated activation energy at MP2 level for N2O dissociation on GaO2‐ZSM‐5 is 43.7 kcal/mol. Four‐order perturbation theory (MP4//MP2) predicts that the activation barriers for nitrous oxide dissociation at 298 K on Ga‐ZSM‐5, GaO‐ZSM‐5, and GaO2‐ZSM‐5 are 13.9, 13.0, and 34.4 kcal/mol, respectively. The calculated energy for desorption of singlet O2 from the 3T−[Ga(O)3]+ cluster at MP2 level is 33.4 kcal/mol. When one takes into account the entropy gained on desorption of singlet O2, the contribution of entropy to the free energy of desorption is TΔS = 12.3 kcal/mol at 298 K. The calculated energy of the singlet oxygen desorption from 3T−[OGaO2]+ cluster ΔH (298 K) = +43.57 kcal/mol and ΔG(298 K) = 30.13 kcal/mol is significantly higher than the barriers of the singlet molecular oxygen desorption from 3T−[Ga(O)3]+ cluster. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
The quantum‐chemical study of small clusters of organic chromophores: Topological analysis and nonlinear optical properties
Authors: Balakina Marina Yu. , Fominykh Olga D.
Published: July 2008

Structure and nonlinear optical properties of small clusters formed of organic chromophores through H‐bonding are studied by the example of dimer and trimer ofp‐nitroaniline (PNA). The analysis of the electron charge density pattern in the bonding region in terms of “Atoms in Molecules” approach is performed, and the values of electron charge density, Laplacian of electron density at critical points, etc. are determined. Topological analysis has given evidence of the existence of three‐center interaction of one amino group hydrogen with oxygens of nitro group of the neighboring PNA, resulting in two H‐bond formation. Solvent effect on the static (hyper)polarizability of the clusters is studied by the example of PNA dimer in acetone in the framework of conventional Polarizable Continuum Model as well as supermolecule and semicontinuum approaches. The essential increase of the cluster hyperpolarizability in comparison with that of a single chromophore is obtained. The account of specific interaction with the solvent molecule is shown to result in moderate or significant enhancement of β∥depending on the structure of the formed cluster. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Institutional history of an interactive science center: The founding and development of the Exploratorium
Authors: Ogawa Rodney T. , Loomis Molly , Crain Rhiannon
Published: July 2008

This study examines the historical conditions that fostered significant reform in science education. To understand these conditions, we employ a framework drawn from the new institutionalism in organization theory to study the founding and early development of the Exploratorium—a prominent science center that greatly impacted the field of science education. We examine how the Exploratorium employed institutional resources that were available in its environment to develop a new type of organization: an interactive science center. Our findings reveal that the Exploratorium was shaped by the state, which includes all levels of government; the mass media; and the professions, including science, education, and museums. In addition, we explore the pivotal role an individual, Frank Oppenheimer, played in leveraging the institutional environment in which an organization was developing. Our findings suggest that (a) reform in science education may be more profoundly advanced by the development of a new type of organization than by “tinkering” with an existing type of organization such as schools, and (b) that interactive science centers should exercise caution in navigating the changing seas of science education by maintaining their core mission and collaborating with new types of organizations that arise in response to the changing environment. © 2008 Wiley Periodicals, Inc. Sci Ed 93: 269–292, 2009
Disparities in defining disparities: Statistical conceptual frameworks
Authors: Duan Naihua , Meng Xiao‐Li , Lin Julia Y. , Chen Chih‐nan , Alegria Margarita
Published: July 2008

Motivated by the need to meaningfully implement the Institute of Medicine's (IOM's) definition of health care disparity, this paper proposes statistical frameworks that lay out explicitly the needed causal assumptions for defining disparity measures. Our key emphasis is that a scientifically defensible disparity measure must take into account the direction of the causal relationship betweenallowable covariatesthat are not considered to be contributors to disparity andnon‐allowable covariatesthat are considered to be contributors to disparity, to avoid flawed disparity measures based on implausible populations that are not relevant for clinical or policy decisions. However, these causal relationships are usually unknown and undetectable from observed data. Consequently, we must make strong causal assumptions in order to proceed. Two frameworks are proposed in this paper, one is theconditional disparityframework under the assumption that allowable covariates impact non‐allowable covariates but notvice versa. The other is themarginal disparityframework under the assumption that non‐allowable covariates impact allowable ones but notvice versa. We establish theoretical conditions under which the two disparity measures are the same and present a theoretical example showing that the difference between the two disparity measures can be arbitrarily large. Using data from the Collaborative Psychiatric Epidemiology Survey, we also provide an example where the conditional disparity is misled by Simpson's paradox, whereas the marginal disparity approach handles it correctly. Copyright © 2008 John Wiley & Sons, Ltd.
Intention‐to‐treat analysis in cluster randomized trials with noncompliance
Authors: Jo Booil , Asparouhov Tihomir , Muthén Bengt O.
Published: July 2008

In cluster randomized trials (CRTs), individuals belonging to the same cluster are very likely to resemble one another, not only in terms of outcomes but also in terms of treatment compliance behavior. Although the impact of resemblance in outcomes is well acknowledged, little attention has been given to the possible impact of resemblance in compliance behavior. This study defines compliance intraclass correlation as the level of resemblance in compliance behavior among individuals within clusters. On the basis of Monte Carlo simulations, it is demonstrated how compliance intraclass correlation affects power to detect intention‐to‐treat (ITT) effect in the CRT setting. As a way of improving power to detect ITT effect in CRTs accompanied by noncompliance, this study employs an estimation method, where ITT effect estimates are obtained based on compliance‐type‐specific treatment effect estimates. A multilevel mixture analysis using an ML‐EM estimation method is used for this estimation. Copyright © 2008 John Wiley & Sons, Ltd.
Estimating local and global measures of association for bivariate interval censored data with a smooth estimate of the density
Authors: Bogaerts Kris , Lesaffre Emmanuel
Published: July 2008

Measures of association for bivariate interval censored data have not yet been studied extensively. Betensky and Finkelstein (Statist. Med. 1999; 18:3101–3109) proposed to calculate Kendall's coefficient of concordance using a multiple imputation technique, but their method becomes computer intensive for moderate to large data sets. We suggest a different approach consisting of two steps. Firstly, a bivariate smooth estimate of the density of log‐event times is determined. The smoothing technique is based on a mixture of Gaussian densities fixed on a grid with weights determined by a penalized likelihood approach. Secondly, given the smooth approximation several local and global measures of association can be estimated readily.

The performance of our method is illustrated by an extensive simulation study and is applied to tooth emergence data of permanent teeth measured on 4468 children from the Signal‐Tandmobiel® study. Copyright © 2008 John Wiley & Sons, Ltd.
Occupational stress and cardiovascular disease
Authors: Byrne D.G. , Espnes Geir Arild
Published: July 2008

Links between occupational stress and cardiovascular risk have long been asserted. This paper reviews the evidence from the simple notion of occupational level and type as a risk through to the more theoretically sophisticated models of occupational stress as a determinant of cardiovascular risk and disease. It maps measures of occupational stress against the three related end points of coronary risk profiles, hypertension and clinical cardiovascular disease. Taken broadly, the evidence is supportive of postulated links. The persuasiveness of the evidence now points to intervention studies in the workplace as the next major focus of research. Copyright © 2008 John Wiley & Sons, Ltd.
A Randomized Trial of a Mental Health Consumer‐Managed Alternative to Civil Commitment for Acute Psychiatric Crisis
Authors: Greenfield Thomas K. , Stoneking Beth C. , Humphreys Keith , Sundby Evan , Bond Jason
Published: July 2008

This experiment compared the effectiveness of an unlocked, mental health consumer‐managed, crisis residential program (CRP) to a locked, inpatient psychiatric facility (LIPF) for adults civilly committed for severe psychiatric problems. Following screening and informed consent, participants (n = 393) were randomized to the CRP or the LIPF and interviewed at baseline and at 30‐day, 6‐month, and 1‐year post admission. Outcomes were costs, level of functioning, psychiatric symptoms, self‐esteem, enrichment, and service satisfaction. Treatment outcomes were compared using hierarchical linear models. Participants in the CRP experienced significantly greater improvement on interviewer‐rated and self‐reported psychopathology than did participants in the LIPF condition; service satisfaction was dramatically higher in the CRP condition. CRP‐style facilities are a viable alternative to psychiatric hospitalization for many individuals facing civil commitment.
A Review of the Treatment of Pelvic Discontinuity
Authors: Villanueva M. , Rios-Luna A. , Pereiro De Lamo J. , Fahandez-Saddi H. , Böstrom M. P. G.
Published: July 2008

Pelvic discontinuity is a complex entity with a high surgical complication rate and no standardized treatment to date. Revision hip arthroplasty in cases of massive bone loss remains a difficult and unsolved problem. The goal of the surgeon is to preserve limb function by restoring bone stock and the biomechanics of the hip. In cases of severe acetabular bone loss, biologic fixation is often inadequate, requiring extensive bone grafting and reconstructive cages. Reconstructive cages are the most commonly used devices and are designed to bridge bone defects, protect the bone graft, and reestablish the rotation center of the hip. A major limitation of current cages is that they do not allow for biologic fixation. We review the options for treating patients with massive bone loss and pelvic discontinuity and discuss therapeutic options and the clinical and radiological criteria for success.
Lumbar Zygapophysial Joint Radiofrequency Denervation: A Long-Term Clinical Outcome Study
Authors: Manejias Elizabeth Marie , Hu Jason , Tatli Yusuf , Lutz Gregory E.
Published: July 2008

Zygapophysial joint (z-joint) pain has long been suggested to be one of the sources of low back pain. Radiofrequency denervation of the medial branches of the dorsal rami to treat z-joint pain is an outpatient minimally invasive treatment option. There have been many short-term studies to determine the outcome of the procedure, but few long-term studies have been conducted. Our goal is to clarify whether radiofrequency denervation has any long-term clinical benefit. In this retrospective cohort study, a total of 42 patients (25 women and 17 men), with an average follow-up of 3.5 years, with clinical signs of zygapophysial joint involvement who had failed conservative treatment (pre-procedure symptom duration mean 6.03 years; range 5 months to 48 years) and had a favorable response to a diagnostic medial branch block or zygapophysial joint injection, were identified. The identified subjects underwent radiofrequency denervation at the Hospital for Special Surgery Physiatry Department from 1998 to 2006. Patient's records were reviewed, and a questionnaire was provided, completed on phone call follow-up, or mailed by the patient. The success of this intervention in providing improvement in pain and function was analyzed using the Numerical Rating Scale (NRS)—11, North American Spine Society (NASS) four-point satisfaction index, and a modified Roland–Morris Disability Questionnaire (RMDQ). Fifty-two percent of patients reported a successful outcome with improved function at a minimum follow-up period of 2 years (mean 3.5 years, range 2–8.8 years). Patients in the failure group were more likely to be older and have moderate to severe neuroforaminal stenosis (77.8%) compared to patients in the success group (24.2%). Radiofrequency denervation in selected patients with chronic zygapophysial joint-mediated low back pain provides long-term reduction in pain and improved function with minimum morbidity.
Nystatin Interferes with the Effects of N‐Methyl‐N′‐nitro‐N‐nitrosoguanidine on Sphingolipid Metabolism in Human FL Cells
Authors: Liu Guangyi , Wang Weimin , Sun Gongping , Ma Xiaoqiong , Liu Ziyang , Yang Jun
Published: July 2008

Previously we have shown that an alkylating agent N‐methyl‐N′‐nitro‐N‐ nitrosoguanidine (MNNG) can induce receptor clustering and the activation of a downstream signal molecule NF‐κB, and that the receptor clustering is associated with changes in sphingolipids metabolism. On the other hand, the polyene antibiotic nystatin can block MNNG‐induced receptor clustering. In this study, using a lipidomic approach, we further evaluated whether nystatin influenced the effects of MNNG on sphingolipids metabolism. It was found that nystatin itself induced changes in the sphingolipids profile in human amnion FL cells to a certain extent, including an increase or decrease of some sphingolipid species. Interestingly, nystatin can block, at least partially, the changes of sphingolipids‐induced by MNNG. In addition, nystatin can also partially inhibit the activation of NF‐κB induced by MNNG. Neither MNNG nor nystatin affects the mRNA levels of serine palmitoyltransferase, acid sphingomyelinase (ASM), and sphingomyelin synthase, key enzymes in the sphingolipids biosynthesis pathway. However, MNNG can activate ASM and neutral sphingomyelinase, while nystatin preincubation inhibits the activation. Taken together, these data suggested that nystatin interferes with the effects of MNNG, and might elicit its function through altered sphingolipids metabolism.
Endogenous small RNAs and antibacterial immunity in plants
Authors: Jin Hailing
Published: July 2008

Small RNAs are non‐coding regulatory RNA molecules that control gene expression by mediating mRNA degradation, translational inhibition, or chromatin modification. Virus‐derived small RNAs induce silencing of viral RNAs and are essential for antiviral defense in both animal and plant systems. The role of host endogenous small RNAs on antibacterial immunity has only recently been recognized. Host disease resistance and defense responses are achieved by activation and repression of a large array of genes. Certain endogenous small RNAs in plants, including microRNAs (miRNAs) and small interfering RNAs (siRNAs), are induced or repressed in response to pathogen attack and subsequently regulate the expression of genes involved in disease resistance and defense responses by mediating transcriptional or post‐transcriptional gene silencing. Thus, these small RNAs play an important role in gene expression reprogramming in plant disease resistance and defense responses. This review focuses on the recent findings of plant endogenous small RNAs in antibacterial immunity.
Ammonium‐dependent hydrogen peroxide production by mitochondria
Authors: Grivennikova Vera G. , Cecchini Gary , Vinogradov Andrei D.
Published: July 2008

NADH‐supported generation of H2O2 by permeabilized rat heart mitochondria was partially prevented by the specific complex I‐directed inhibitor, NADH‐OH, and was significantly stimulated by ammonium. Ammonium did not affect H2O2 production by complex I in coupled submitochondrial particles. The soluble mitochondrial matrix protein fraction catalyzed NADH‐dependent H2O2 production, which was greatly (∼10‐fold) stimulated by ammonium. We conclude that complex I is not the major contributor to mitochondrial superoxide (hydrogen peroxide) generation and that there are specific ammonium‐sensitive NADH:oxygen oxidoreductase(s) in the mitochondrial matrix which are responsible for mitochondrial H2O2 production.
A novel interaction between the proto‐oncogene Evi1 and histone methyltransferases, SUV39H1 and G9a
Authors: Spensberger Dominik , Delwel Ruud
Published: July 2008

The transcription factor ecotropic viral integration site 1 (Evi1) is associated with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) in patients due to chromosomal aberration of chromosome 3. Here we show that Evi1 interacts with the histone methyltransferase SUV39H1. The interaction requires the N‐terminal part of Evi1 and the H3‐specific histone methyltransferase domain, SET, of SUV39H1 without Evi1 having an inhibitory effect on SUV39H1 methyltransferase activity. Presence of SUV39H1 enhances Evi1 transcriptional repression in a dose dependent manner. In addition, Evi1 also interacts with another histone methyltransferase, G9a, but not with SET9. Our data establish an epigenetic role of Evi1 in cell transformation by recruiting higher order chromatin remodeling complexes.