bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous activation of PLA2 and PLC are required to promote acrosomal reaction stimulated by progesterone via G‐proteins
Authors: Pietrobon Elisa Olivia , Soria Mariana , Domínguez Luis Ángel , Monclus María de los ángeles , Fornés Miguel Walter 
Published: November 2004

AbstractThe acrosome reaction (AR) is a special exocytotic process promoted by signal transduction pathways studied in many laboratories. Progesterone (P4) is one of the trigger molecules proposed. Upon the binding of P4 to its receptor, several molecules could be activated, including G‐proteins, phospholipase A2 (PLA2), and phospholipase C (PLC). The role of these molecules was analyzed in this study using the Chlortetracycline (CTC) protocol to detect and quantify the AR. Incubation of capacitated sperm cells with GTPγs (GTPγs, a mimetic of G‐protein activation), arachidonic acid (AA, product of PLA2 action), or phorbol ester (PMA, an activator of PLC) for 15 min increased the AR to a similar percentage as P4. Conversely, a decrease in the AR was detected when sperm cells were incubated with P4 after preincubation with: GDPβS (GDP, an inhibitor of G‐protein activation), ONO RS‐82 (ONO, an inhibitor of PLA2), or neomycin (Neo, an inhibitor of PLC) for 15 min. To analyze the activation sequence of G proteins, PLA2, and PLC combinations of these mimetic/inhibitors were used during successive incubation periods. Inhibition promoted by GDP, ONO, and Neo were overcome by 15‐min incubation with GTPγs, AA, or PMA, respectively. But GTPγs or P4 did not reverse the inhibition due to incubation with Neo and ONO. Interestingly, this dual inhibition was reverted by another 15‐min incubation with AA or PMA. Results presented here could indicate that the AR triggered by P4 is driven by activation of G‐proteins, that in turn activate PLA2 and PLC simultaneously, that finally promote acrosomal exocytosis. Mol. Reprod. Dev. 70: 58–63, 2004. © 2004 Wiley‐Liss, Inc.
Reflection–absorption infrared spectroscopy investigation of the crystallization kinetics of poly(ethylene terephthalate) ultrathin films
Authors: Zhang Ying , Lu Yonglai , Duan Yongxin , Zhang Jianming , Yan Shouke , Shen Deyan 
Published: November 2004

AbstractReflection–absorption infrared spectroscopy was used to study the crystallization behavior of poly(ethylene terephthalate) (PET) ultrathin films. The crystallinity of ultrathin films was estimated by the fraction of trans conformers of PET. The isothermal and nonisothermal crystallization kinetics of ultrathin films with different thicknesses were investigated. The thinner PET film showed slower kinetics during isothermal crystallization than the thicker film. Moreover, the final crystallinity of films with various thicknesses were reduced with decreasing thickness. An Avrami equation was used to fit the acquired results. The Avrami exponents decreased with the film thickness. As for the nonisothermal crystallization, the cold‐crystallization starting temperature shifted to a lower temperature as the film thickness increased. The influence of the substrate on the crystallization kinetics of the films was also studied. The half‐crystallization times and final crystallinities of ultrathin films adsorbed onto a self‐assembled‐monolayer‐treated surface and an untreated substrate were clearly different, although their thickness dependence was similar. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4440–4447, 2004
Solvation influences flap collapse in HIV‐1 protease
Authors: Meagher Kristin L. , Carlson Heather A. 
Published: November 2004

AbstractHIV‐1 protease (HIVp) is an important target for the development of therapies to treat AIDS and is one of the classic examples of structure‐based drug design. The flap region of HIVp is known to be highly flexible and undergoes a large conformational change upon binding a ligand. Accurately modeling the inherent flexibility of the HIVp system is critical for developing new methods for structure‐based drug design. We report several 3‐ns molecular dynamics simulations investigating the role of solvation in HIVp flap rearrangement. Using an unliganded crystal structure of HIVp, other groups have observed flap reorganization on the nanosecond timescale. We have also observed rapid, initial flap movement, but we propose that it may be caused by system setup. The initial solvation of the system creates vacuum regions around the protein that may encourage large conformational deformities. By reducing the vacuum space created by the solvation routine, the observed flap collapse is attenuated. Also, a more thorough equilibration procedure preserves a more stable protein conformation over the course of the simulation. Proteins 2005. © 2004 Wiley‐Liss, Inc.
Hydrostatic pressure effects on the structural and electronic properties of carbon nanotubes
Authors: Capaz Rodrigo B. , Spataru Catalin D. , Tangney Paul , Cohen Marvin L. , Louie Steven G. 
Published: November 2004

AbstractThis issue's Editor's Choice [1] is a theoretical study of the properties of single‐wall carbon nanotubes (SWNTs) under hydro‐static pressure. The cover picture is a snapshot of room‐temperature molecular dynamics simulations of a chiral (8,7) SWNT at a pressure of 4 GPa, where a symmetry‐breaking collapse of the tube into a flat shape is observed.This paper is an invited presentation from the 11th Interna‐tional Conference on High Pressure Semiconductor Physics (HPSP‐11), held in Berkeley, California, USA, 2–5 August 2004. The Proceedings of this conference series have been published for the fifth time in physica status solidi (b).The first author, Rodrigo Barbosa Capaz, is Associate Professor of Physics at Universidade Federal do Rio de Janeiro and works on electronic properties and computer modeling of materials.
Electron transport with dissipation: A quantum kinetic approach
Authors: Gebauer Ralph , Car Roberto 
Published: November 2004

AbstractWe present a method for calculating electronic transport properties at the nanoscale. In this approach we describe the electron kinetics in the presence of an external field and of a heat bath. While the electric field accelerates the electrons, energy is dissipated as a result of interaction with the heat bath, allowing the system to reach steady state. The method is based on a Liouville master equation that constitutes a fully quantum generalization of the Boltzmann kinetic equation. As an example we report an application to transport through a double‐barrier resonant tunneling structure. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Fermion particle density equations in relation to relativistic density functional theory
Authors: Howard I. A. , March N. H. 
Published: November 2004

AbstractRelativistic density functional theory goes back at least to the work of Vallarta and Rosen. This represents the generalization of the Thomas–Fermi method to embody the kinetic energy of an electron of momentum p and rest mass m0 as given by special relativity theory in the chemical potential Euler equation. Here we set up a relativistic density functional theory by heuristic arguments that start from well‐established exact nonrelativistic differential equations for the Fermion density n(r) in model systems. We focus first on the differential equation of Lawes and March for one‐dimensional harmonic confinement. Into their result we introduce the finiteness of the velocity of light c by replacing the Lawes–March differential equation for the Fermion density n(x) by a difference equation for the relativistic Fermion density in which the Compton wavelength h/m0c, with m0 the Fermion rest mass, plays an important role. As we take the nonrelativistic limit c → ∞, we regain the exact nonrelativistic result. Contact is then established with the Vallarta–Rosen treatment in the limit when a large number N of Fermions are harmonically confined. The remaining models investigated are two‐electron in character. Relativistic difference equations to determine the density are again presented, for two such models. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
DFT energy derivatives and their renormalization in molecular vibrations
Authors: Ordon Piotr , Komorowski Ludwik 
Published: November 2004

AbstractProperties of the energy function E(N, Q) and the thermodynamic potential Ω(μ, Q) expressed in terms of the number of electrons (N) and the nuclear positions (Q) rather than conventionally, by the electrostatic potential, ν(r), have been analyzed. The whole body of derivatives up to the third order is presented for each function. Renormalization of the basic derivatives explored in conceptual density functional theory has been demonstrated (chemical potential μ, global hardness η, number of electrons N, global softness S) as a result of coupling between the oscillatory motion of nuclei and the change in N or μ, for E and Ω, respectively. Exact result of renormalization crucially depends on the level of approximation. Extending the analysis beyond the second order was possible by adopting the Liu and Parr–type approximation to the energy function. It has been determined that first derivatives (μ, N) change their values when found beyond the vibrational energy minimum only. Second derivatives (η, S) both get renormalized even at the energy minimum, and they no longer conform to the reciprocity condition (ηS ≠ 1). Possible implications for the reactivity of oscillating species have been indicated. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Percolation in Voronoi tilings
Authors: Balister P. , Bollobás B. , Quas A. 
Published: November 2004

AbstractWe consider a percolation process on a random tiling of ℝd into Voronoi cells based on points of a realization of a Poisson process. We prove the existence of a phase transition as the proportion p of open cells is varied and provide estimates for the critical probability pc. Specifically, we prove that for large d, 2−d(9d log d)−1 ≤ pc(d) ≤ C2−d$\sqrt{d}$ log d. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2005
Responsible Care© Programs for Hazardous Chemicals
Authors: Weiler Ernest D. , Jayjock Michael A. , Lewis Philip G. 
Published: November 2004

AbstractThis article describes the development, use, and learnings of a comprehensive Responsible Care® program as applied to the management of hazardous substances at various stages during the life cycle of the product. The article offers specific examples for stewardship programs in the biocide industry, and discusses the role of the medical community. © 2001 John Wiley & Sons, Inc.
The MTBE Threat to Our Water Supply: How to Detect and Remediate It
Authors: Kahler David 
Published: November 2004

AbstractMethyl tertiary butyl ether, a gasoline additive once used to reduce air pollution, is now contaminating water sources around the United States. Monitoring for this chemical—and remediating it where it is found—should be an environmental priority. © 2001 John Wiley & Sons, Inc.
Quantifying the Impact of Corporate Environmental Performance on Shareholder Value
Authors: Repetto Robert , Austin Duncan 
Published: November 2004

AbstractThis article demonstrates an approach for analyzing and communicating the financial implications of a company's environmental exposures. In environmentally sensitive industries, this approach can help companies to benchmark themselves against rivals, to identify major sources of environmental risk and opportunity, to assign financial values to risk‐mitigating options, and to communicate their environmental strategies to the investment community and other stake‐holders. © 2000 World Resources Institute. Used with permission.
Single‐chain antibodies for the conformation‐specific blockade of activated platelet integrin αIIbβ3 designed by subtractive selection from naïve human phage libraries
Authors: Schwarz Meike , Röttgen Peter , Takada Yoshiazuku , Gall Fabrice Le , Knackmuss Stefan , Bassler Nicole , Büttner Claudia , Little Melvyn , Bode Christoph , Peter Karlheinz 
Published: November 2004

ABSTRACTBinding of fibrinogen to platelet integrin αIIbβ3 mediates platelet aggregation, and thus inhibition of αIIbβ3 represents a powerful therapeutic strategy in cardiovascular medicine. However, the currently used inhibitors of αIIbβ3 demonstrate several adverse effects like thrombocytopenia and bleeding, which are associated with their property to bind to non‐activated αIIbβ3. To circumvent these problems, we designed blocking single‐chain antibody‐fragments (scFv) that bind to αIIbβ3 exclusively in its activated conformation. Two naïve phage libraries were created: a natural phage library, based on human lymphocyte cDNA, and a synthetic library, with randomized VHCDR3. We performed serial rounds of subtractive panning with depletion on non‐activated and selection on activated αIIbβ3, which were provided on resting and ADP‐stimulated platelets and CHO cells, expressing wild‐type or mutated and thereby activated αIIbβ3. In contrast to isolated, immobilized targets, as generally used for phage display, this unique cell‐based approach for panning allowed the preservation of functional integrin conformation. Thereby, we obtained several scFv‐clones that demonstrated exclusive binding to activated platelets and complete inhibition of fibrinogen binding and platelet aggregation. Interestingly, all activation‐specific clones contained an RXD pattern in the HCDR3. Binding studies on transiently expressed point mutants and mouse‐human domain‐switch mutants of αIIbβ3 indicate a binding site similar to fibrinogen. In conclusion, we generated human activation‐specific scFvs against αIIbβ3, which bind selectively to activated αIIbβ3 and thereby potently inhibit fibrinogen binding to αIIbβ3 and platelet aggregation.
Inhibition of host connective tissue growth factor expression: a novel Trypanosoma cruzi‐mediated response
Authors: Unnikrishnan Meera , A. Burleigh Barbara 
Published: November 2004

ABSTRACTConnective tissue growth factor (CTGF) is a secreted cytokine that plays a fundamental role in the development of tissue fibrosis by mediating many of the profibrotic effects of TGF‐β. We present the novel finding that the intracellular pathogen Trypanosoma cruzi elicits immediate and sustained repression of basal CTGF expression in dermal fibroblasts, followed by down‐regulation of the extracellular matrix proteins, fibronectin, and collagen I α1. To address mechanisms underlying this response, the major CTGF‐regulating pathways were investigated. We report that both T. cruzi trypomastigotes and secreted parasite factor(s) antagonize TGF‐β‐dependent induction of CTGF in fibroblasts. Of the TGF‐β‐dependent signaling pathways required for CTGF expression, we demonstrate that T. cruzi interferes with cellular Erk1/2 phosphorylation but not Smad3 signaling. While increased stimulation of Erk phosphorylation alone was insufficient to override the parasite‐mediated repression of CTGF, stimulation of fibroblasts with increased concentrations of TGF‐β, which activates both Smad3 and Erk1/2, completely abrogated this inhibition. Together with the finding that T. cruzi‐mediated down‐regulation of CTGF expression requires de novo host cell protein synthesis, our data indicate that the unique ability of T. cruzi to interfere with the host fibrogenic response is a complex process requiring input from multiple host cell signaling pathways.—Unnikrishnan, M., Burleigh, B. A. Inhibition of host connective tissue growth factor expression: a novel Trypanosoma cruzi‐mediated response. FASEB J. 18, 1625–1635 (2004)
Intramyocardial lipid accumulation in the failing human heart resembles the lipotoxic rat heart
Authors: Sharma Saumya , Adrogue Julia V. , Golfman Leonard , Uray Ivan , Lemm John , Youker Keith , Noon George P. , Frazier O. H. , Taegtmeyer Heinrich 
Published: November 2004

ABSTRACTIn animal models of lipotoxicity, accumulation of triglycerides within cardiomyocytes is associated with contractile dysfunction. However, whether intramyocardial lipid deposition is a feature of human heart failure remains to be established. We hypothesized that intramyocardial lipid accumulation is a common feature of non‐ischemic heart failure and is associated with changes in gene expression similar to those found in an animal model of lipotoxicity. Intramyocardial lipid staining with oil red O and gene expression analysis was performed on heart tissue from 27 patients (9 female) with non‐ischemic heart failure. We determined intramyocardial lipid, gene expression, and contractile function in hearts from 6 Zucker diabetic fatty (ZDF) and 6 Zucker lean (ZL) rats. Intramyocardial lipid overload was present in 30% of non‐ischemic failing hearts. The highest levels of lipid staining were observed in patients with diabetes and obesity (BMI>30). Intramyocardial lipid deposition was associated with an up‐regulation of peroxisome proliferator‐activated receptor a (PPARα) ‐regulated genes, myosin heavy chain β (MHC‐β), and tumor necrosis factor α (TNF‐α). Intramyocardial lipid overload in the hearts of ZDF rats was associated with contractile dysfunction and changes in gene expression similar to changes found in failing human hearts with lipid overload. Our findings identify a subgroup of patients with heart failure and severe metabolic dysregulation characterized by intramyocardial triglyceride overload and changes in gene expression that are associated with contractile dysfunction.—Sharma, S., Adrogue, J. V., Golfman, L., Uray, I., Lemm, J., Youker, K., Noon, G. P., Frazier, O. H., Taegtmeyer, H. Intramyocardial lipid accumulation in the failing human heart resembles the lipotoxic rat heart. FASEB J. 18, 1692–1700 (2004)
PIL5, a Phytochrome-Interacting Basic Helix-Loop-Helix Protein, Is a Key Negative Regulator of Seed Germination inArabidopsis thaliana [W]
Authors: Oh Eunkyoo , Kim Jonghyun , Park Eunae , Kim Jeong-Il , Kang Changwon , Choi Giltsu 
Published: November 2004

AbstractThe first decision made by an angiosperm seed, whether to germinate or not, is based on integration of various environmental signals such as water and light. The phytochromes (Phys) act as red and far-red light (Pfr) photoreceptors to mediate light signaling through yet uncharacterized pathways. We report here that the PIF3-like 5 (PIL5) protein, a basic helix-loop-helix transcription factor, is a key negative regulator of phytochrome-mediated seed germination. PIL5 preferentially interacts with the Pfr forms of Phytochrome A (PhyA) and Phytochrome B (PhyB). Analyses of a pil5 mutant in conjunction with phyA and phyB mutants, a pif3 pil5 double mutant, and PIL5 overexpression lines indicate that PIL5 is a negative factor in Phy-mediated promotion of seed germination, inhibition of hypocotyl negative gravitropism, and inhibition of hypocotyl elongation. Our data identify PIL5 as the first Phy-interacting protein that regulates seed germination.
A Novel Molecular Recognition Motif Necessary for Targeting Photoactivated Phytochrome Signaling to Specific Basic Helix-Loop-Helix Transcription Factors[W]
Authors: Khanna Rajnish , Huq Enamul , Kikis Elise A. , Al-Sady Bassem , Lanzatella Christina , Quail Peter H. 
Published: November 2004

AbstractThe phytochrome (phy) family of sensory photoreceptors (phyA to phyE) in Arabidopsis thaliana control plant developmental transitions in response to informational light signals throughout the life cycle. The photoactivated conformer of the photoreceptor Pfr has been shown to translocate into the nucleus where it induces changes in gene expression by an unknown mechanism. Here, we have identified two basic helix-loop-helix (bHLH) transcription factors, designated PHYTOCHROME-INTERACTING FACTOR5 (PIF5) and PIF6, which interact specifically with the Pfr form of phyB. These two factors cluster tightly with PIF3 and two other phy-interacting bHLH proteins in a phylogenetic subfamily within the large Arabidopsis bHLH (AtbHLH) family. We have identified a novel sequence motif (designated the active phytochrome binding [APB] motif) that is conserved in these phy-interacting AtbHLHs but not in other noninteractors. Using the isolated domain and site-directed mutagenesis, we have shown that this motif is both necessary and sufficient for binding to phyB. Transgenic expression of the native APB-containing AtbHLH protein, PIF4, in a pif4 null mutant, rescued the photoresponse defect in this mutant, whereas mutated PIF4 constructs with site-directed substitutions in conserved APB residues did not. These data indicate that the APB motif is necessary for PIF4 function in light-regulated seedling development and suggest that conformer-specific binding of phyB to PIF4 via the APB motif is necessary for this function in vivo. Binding assays with the isolated APB domain detected interaction with phyB, but none of the other four Arabidopsis phys. Collectively, the data suggest that the APB domain provides a phyB-specific recognition module within the AtbHLH family, thereby conferring photoreceptor target specificity on a subset of these transcription factors and, thus, the potential for selective signal channeling to segments of the transcriptional network.
A Conserved Transcript Pattern in Response to a Specialist and a Generalist Herbivorew⃞
Authors: Reymond Philippe , Bodenhausen Natacha , Van Poecke Remco M.P. , Krishnamurthy Venkatesh , Dicke Marcel , Farmer Edward E. 
Published: November 2004

AbstractTranscript patterns elicited in response to attack reveal, at the molecular level, how plants respond to aggressors. These patterns are fashioned both by inflicted physical damage as well as by biological components displayed or released by the attacker. Different types of attacking organisms might therefore be expected to elicit different transcription programs in the host. Using a large-scale DNA microarray, we characterized gene expression in damaged as well as in distal Arabidopsis thaliana leaves in response to the specialist insect, Pieris rapae. More than 100 insect-responsive genes potentially involved in defense were identified, including genes involved in pathogenesis, indole glucosinolate metabolism, detoxification and cell survival, and signal transduction. Of these 114 genes, 111 were induced in Pieris feeding, and only three were repressed. Expression patterns in distal leaves were markedly similar to those of local leaves. Analysis of wild-type and jasmonate mutant plants, coupled with jasmonate treatment, showed that between 67 and 84% of Pieris-regulated gene expression was controlled, totally or in part, by the jasmonate pathway. This was correlated with increased larval performance on the coronatine insensitive1 glabrous1 (coi1-1 gl1) mutant. Independent mutations in COI1 and GL1 led to a faster larval weight gain, but the gl1 mutation had relatively little effect on the expression of the insect-responsive genes examined. Finally, we compared transcript patterns in Arabidopis in response to larvae of the specialist P. rapae and to a generalist insect, Spodoptera littoralis. Surprisingly, given the complex nature of insect salivary components and reported differences between species, almost identical transcript profiles were observed. This study also provides a robustly characterized gene set for the further investigation of plant–insect interaction.