bluuebunny/crossref_metadata_2025 huggingface dataset:
Sharp Corner Functions for Mindlin Plates
Authors: McGee O. G. , Kim J. W. , Leissa A. W.
Published: February 2005

Transverse displacement and rotation eigenfunctions for the bending of moderately thick plates are derived for the Mindlin plate theory so as to satisfy exactly the differential equations of equilibrium and the boundary conditions along two intersecting straight edges. These eigenfunctions are in some ways similar to those derived by Max Williams for thin plates a half century ago. The eigenfunctions are called “corner functions,” for they represent the state of stress currently in sharp corners, demonstrating the singularities that arise there for larger angles. The corner functions, together with others, may be used with energy approaches to obtain accurate results for global behavior of moderately thick plates, such as static deflections, free vibration frequencies, buckling loads, and mode shapes. Comparisons of Mindlin corner functions with those of thin-plate theory are made in this work, and remarkable differences are found.
An Electric Node Concept for Solid-Shell Elements for Laminate Composite Piezoelectric Structures
Authors: Yao Lin-Quan , Lu Li
Published: February 2005

The eight-node solid-shell finite element models have been developed for the analysis of laminated composite plate/shell structures embedded with piezoelectric actuators and sensors. To resolve the locking problems of the solid-shell elements in laminated materials and improve accuracy, the assumed natural strain method and hybrid stress method are employed. Introduction of the concept of the electric nodes can effectively eliminate the burden of constraining the equality of the electric potential for the nodes lying on the same electrode. Furthermore, the nonlinear electric potential distribution in piezoelectric layer is described by introducing internal electric potential. The developed finite element models, especially electric potential node model, are simpler over other models but can still obtain same accuracy as exact solution described. Several examples are studied and compared with exact solution and other predicted results to illustrate the accuracy of the present model, and efficacy and effect caused by nonlinear electric potential distribution on frequency and electric fields in smart structure modeling.
Steady Mechanics of Belt-Pulley Systems
Authors: Kong Lingyuan , Parker Robert G.
Published: February 2005

Steady state analysis of a two-pulley belt drive is conducted where the belt is modeled as a moving Euler-Bernoulli beam with bending stiffness. Other factors in the classical creep theory, such as elastic extension and Coulomb friction with the pulley, are retained, and belt inertia is included. Inclusion of the bending stiffness leads to nonuniform distribution of the tension and speed in the belt spans and alters the belt departure points from the pulley. Solutions for these quantities are obtained by a numerical iteration method that generalizes to n-pulley systems. The governing boundary value problem (BVP), which has undetermined boundaries due to the unknown belt-pulley contact points, is first converted to a standard fixed boundary form. This form is readily solvable by general purpose BVP solvers. Bending stiffness reduces the wrap angles, improves the power efficiency, increases the span tensions, and reduces the maximum transmissible moment.
Calculation of the Response of a Composite Plate to Localized Dynamic Surface Loads Using a New Wave Number Integral Method
Authors: Banerjee Sauvik , Prosser William , Mal Ajit
Published: February 2005

This study is motivated by the need for an efficient and accurate tool to analyze the wave field produced by localized dynamic sources on the surface or the interior of isotropic plates and anisotropic composite laminates. A semi-analytical method based on the wave number integral representation of the elastodynamic field is described that reduces the overall computational effort significantly over other available methods. This method is used to calculate the guided wave field produced in a thin unidirectional graphite/epoxy composite laminate by a dynamic surface point load. The results are compared with those obtained from a finite element analysis, showing excellent agreement, except for minor differences at higher frequencies. A recently discovered feature of the calculated surface motion, namely, a spatially periodic “phase reversal” of the main pulse with propagation distance, is observed in both cases. The present work is expected to be helpful in developing impact damage monitoring systems in defect-critical structural components through real time analysis of acoustic emission wave forms.
Amino-Terminal Protein Fusions to the TraR Quorum-Sensing Transcription Factor Enhance Protein Stability and Autoinducer-Independent Activity
Authors: Chai Yunrong , Winans Stephen C.
Published: February 2005

TraR ofAgrobacterium tumefaciensis a member of the LuxR family of quorum-sensing transcription factors and regulates genes required for conjugation and vegetative replication of the tumor-inducing (Ti) plasmid in the presence of the autoinducer 3-oxooctanoyl-homoserine lactone (OOHL). In the absence of OOHL, TraR is rapidly destroyed by proteolysis, suggesting that this ligand is required for TraR folding. To date, no TraR variant has been found that is active in the absence of OOHL. In this study, we conducted whole-cell and plasmid mutagenesis experiments to search for constitutive mutations oftraRand identified two constitutive alleles. Surprisingly, neither contained a point mutation within thetraRgene, but rather, both encoded fusion proteins between TraR and the N-terminal domain of an aminoglycosideN-acetyltransferase, encoded by a plasmid-borne antibiotic resistance gene present in the original strain. Data from Western immunoblot assays, pulse-chase assays, and immunoprecipitation assays show that these fusion proteins are far more stable to proteolysis than native apo-TraR. We also constructed a library oftraRalleles encoding random amino-terminal fusions and selected for constitutive TraR activity. Five independent fusion proteins were identified by this approach. These fusion proteins accumulated to far higher levels than wild-type TraR in the absence of OOHL. One of these fusions was overexpressed inEscherichia coliand showed detectabletrabox binding in the absence of OOHL. These data suggest that the native amino terminus of TraR may signal proteolysis and that fusing it to other proteins might sequester it from intracellular proteases.
Identification and Characterization of a Novel Allele of
Escherichia coli dnaB
Helicase That Compromises the Stability of Plasmid P1
Authors: Slavcev Roderick A. , Funnell Barbara E.
Published: February 2005

Bacteriophage P1 lysogenizes
Escherichia coli
cells as a plasmid with approximately the same copy number as the copy number of the host chromosome. Faithful inheritance of the plasmids relies upon proper DNA replication, as well as a partition system that actively segregates plasmids to new daughter cells. We genetically screened for
E. coli
chromosomal mutations that influenced P1 stability and identified a novel temperature-sensitive allele of the
dnaB
helicase gene (
dnaB277
) that replaces serine 277 with a leucine residue (DnaB S277L). This allele conferred a severe temperature-sensitive phenotype to the host;
dnaB277
cells were not viable at temperatures above 34°C. Shifting
dnaB277
cells to 42°C resulted in an immediate reduction in the rate of DNA synthesis and extensive cell filamentation. The
dnaB277
allele destabilized P1 plasmids but had no significant influence on the stability of the F low-copy-number plasmid. This observation suggests that there is a specific requirement for DnaB in P1 plasmid maintenance in addition to the general requirement for DnaB as the replicative helicase during elongation.
Weighted Genome Trees: Refinements and Applications
Authors: Gophna Uri , Doolittle W. Ford , Charlebois Robert L.
Published: February 2005

There are many ways to group completed genome sequences in hierarchical patterns (trees) reflecting relationships between their genes. Such groupings help us organize biological information and bear crucially on underlying processes of genome and organismal evolution. Genome trees make use of all comparable genes but can variously weight the contributions of these genes according to similarity, congruent patterns of similarity, or prevalence among genomes. Here we explore such possible weighting strategies, in an analysis of 142 prokaryotic and 5 eukaryotic genomes. We demonstrate that alternate weighting strategies have different advantages, and we propose that each may have its specific uses in systematic or evolutionary biology. Comparisons of results obtained with different methods can provide further clues to major events and processes in genome evolution.
Reconstitution of O-Specific Lipopolysaccharide Expression in
Burkholderia cenocepacia
Strain J2315, Which Is Associated with Transmissible Infections in Patients with Cystic Fibrosis
Authors: Ortega Ximena , Hunt Tracey A. , Loutet Slade , Vinion-Dubiel Arlene D. , Datta Anup , Choudhury Biswa , Goldberg Joanna B. , Carlson Russell , Valvano Miguel A.
Published: February 2005

Burkholderia cenocepacia
is an opportunistic bacterium that infects patients with cystic fibrosis.
B. cenocepacia
strains J2315, K56-2, C5424, and BC7 belong to the ET12 epidemic clone, which is transmissible among patients. We have previously shown that transposon mutants with insertions within the O antigen cluster of strain K56-2 are attenuated for survival in a rat model of lung infection. From the genomic DNA sequence of the O antigen-deficient strain J2315, we have identified an O antigen lipopolysaccharide (LPS) biosynthesis gene cluster that has an IS
402
interrupting a predicted glycosyltransferase gene. A comparison with the other clonal isolates revealed that only strain K56-2, which produced O antigen and displayed serum resistance, lacked the insertion element inserted within the putative glycosyltransferase gene. We cloned the uninterrupted gene and additional flanking sequences from K56-2 and conjugated this plasmid into strains J2315, C5424, and BC7. All the exconjugants recovered the ability to form LPS O antigen. We also determined that the structure of the strain K56-2 O antigen repeat, which was absent from the LPS of strain J2315, consisted of a trisaccharide unit made of rhamnose and two
N
-acetylgalactosamine residues. The complexity of the gene organization of the K56-2 O antigen cluster was also investigated by reverse transcription-PCR, revealing several transcriptional units, one of which also contains genes involved in lipid A-core oligosaccharide biosynthesis.
The PuhB Protein of
Rhodobacter capsulatus
Functions in Photosynthetic Reaction Center Assembly with a Secondary Effect on Light-Harvesting Complex 1
Authors: Aklujkar Muktak , Prince Roger C. , Beatty J. Thomas
Published: February 2005

The core of the photosynthetic apparatus of purple photosynthetic bacteria such as
Rhodobacter capsulatus
consists of a reaction center (RC) intimately associated with light-harvesting complex 1 (LH1) and the PufX polypeptide. The abundance of the RC and LH1 components was previously shown to depend on the product of the
puhB
gene (formerly known as
orf214
). We report here that disruption of
puhB
diminishes RC assembly, with an indirect effect on LH1 assembly, and reduces the amount of PufX. Under semiaerobic growth conditions, the core complex was present at a reduced level in
puhB
mutants. After transfer of semiaerobically grown cultures to photosynthetic (anaerobic illuminated) conditions, the RC/LH1 complex became only slightly more abundant, and the amount of PufX increased as cells began photosynthetic growth. We discovered that the photosynthetic growth of
puhB
disruption strains of
R. capsulatus
starts after a long lag period, which is due to physiological adaptation rather than secondary mutations. Using a hybrid protein expression system, we determined that the three predicted transmembrane segments of PuhB are capable of spanning a cell membrane and that the second transmembrane segment could mediate self-association of PuhB. We discuss the possible function of PuhB as a dimeric RC assembly factor.
High- and Low-Threshold Genes in the Spo0A Regulon ofBacillus subtilis
Authors: Fujita Masaya , González-Pastor José Eduardo , Losick Richard
Published: February 2005

The master regulator for entry into sporulation inBacillus subtilisis the response regulator Spo0A, which directly governs the expression of about 121 genes. Using cells in which the synthesis of Spo0A was under the control of an inducible promoter or in which production of the regulatory protein was impaired by a promoter mutation, we found that sporulation required a high (threshold) level of Spo0A and that many genes in the regulon differentially responded to high and low doses of the regulator. We distinguished four categories of genes, as follows: (i) those that required a high level of Spo0A to be activated, (ii) those that required a high level of Spo0A to be repressed, (iii) those that were activated at a low level of the regulator, and (iv) those that were repressed at a low dose of the regulator. Genes that required a high dose of Spo0A to be activated were found to have low binding constants for the DNA-binding protein. Some genes that were turned on at a low dose of Spo0A either had a high binding constant for the regulatory protein or were activated by an indirect mechanism involving Spo0A-mediated relief of repression by the repressor protein AbrB. We propose that progressive increases in the level of Spo0A leads to an early phase of transcription in which genes that play auxiliary roles in development, such as cannibalism and biofilm formation, are turned on and a later phase in which genes that play a direct role in sporulation are activated.
Novel Genes of the
dsr
Gene Cluster and Evidence for Close Interaction of Dsr Proteins during Sulfur Oxidation in the Phototrophic Sulfur Bacterium
Allochromatium vinosum
Authors: Dahl Christiane , Engels Sabine , Pott-Sperling Andrea S. , Schulte Andrea , Sander Johannes , Lübbe Yvonne , Deuster Oliver , Brune Daniel C.
Published: February 2005

Seven new genes designated
dsrLJOPNSR
were identified immediately downstream of
dsrABEFHCMK
, completing the
dsr
gene cluster of the phototrophic sulfur bacterium
Allochromatium vinosum
D (DSM 180
T
). Interposon mutagenesis proved an essential role of the encoded proteins for the oxidation of intracellular sulfur, an obligate intermediate during the oxidation of sulfide and thiosulfate. While
dsrR
and
dsrS
encode cytoplasmic proteins of unknown function, the other genes encode a predicted NADPH:acceptor oxidoreductase (DsrL), a triheme
c
-type cytochrome (DsrJ), a periplasmic iron-sulfur protein (DsrO), and an integral membrane protein (DsrP). DsrN resembles cobyrinic acid
a,c
-diamide synthases and is probably involved in the biosynthesis of siro(heme)amide, the prosthetic group of the
dsrAB
-encoded sulfite reductase. The presence of most predicted Dsr proteins in
A. vinosum
was verified by Western blot analysis. With the exception of the constitutively present DsrC, the formation of Dsr gene products was greatly enhanced by sulfide. DsrEFH were purified from the soluble fraction and constitute a soluble α
2
β
2
γ
2
-structured 75-kDa holoprotein. DsrKJO were purified from membranes pointing at the presence of a transmembrane electron-transporting complex consisting of DsrKMJOP. In accordance with the suggestion that related complexes from dissimilatory sulfate reducers transfer electrons to sulfite reductase, the
A. vinosum
Dsr complex is copurified with sulfite reductase, DsrEFH, and DsrC. We therefore now have an ideal and unique possibility to study the interaction of sulfite reductase with other proteins and to clarify the long-standing problem of electron transport from and to sulfite reductase, not only in phototrophic bacteria but also in sulfate-reducing prokaryotes.
A Three-Component Regulatory System Regulates Biofilm Maturation and Type III Secretion inPseudomonas aeruginosa
Authors: Kuchma Sherry L. , Connolly John P. , O'Toole George A.
Published: February 2005

Biofilms are structured communities found associated with a wide range of surfaces. Here we report the identification of a three-component regulatory system required for biofilm maturation byPseudomonas aeruginosastrain PA14. A transposon mutation that altered biofilm formation in a 96-well dish assay originally defined this locus, which is comprised of genes for a putative sensor histidine kinase and two response regulators and has been designatedsadARS. Nonpolar mutations in any of thesadARSgenes result in biofilms with an altered mature structure but do not confer defects in growth or early biofilm formation, swimming, or twitching motility. After 2 days of growth under flowing conditions, biofilms formed by the mutants are indistinguishable from those formed by the wild-type (WT) strain. However, by 5 days, mutant biofilms appear to be more homogeneous than the WT in that they fail to form large and distinct macrocolonies and show a drastic reduction in water channels. We propose that thesadARSthree-component system is required for later events in biofilm formation on an abiotic surface. Semiquantitative reverse transcription-PCR analysis showed that there is no detectable change in expression of thesadARSgenes when cells are grown in a planktonic culture versus a biofilm, indicating that this locus is not itself induced during or in response to biofilm formation. DNA microarray studies were used to identify downstream targets of the SadARS system. Among the genes regulated by the SadARS system are those required for type III secretion. Mutations in type III secretion genes result in strains with enhanced biofilm formation. We propose a possible mechanism for the role that the SadARS system plays in biofilm formation.
Alpha-Subunit Positions Methionine 180 and Glutamate 214 of
Pseudomonas stutzeri
OX1 Toluene-
o
-Xylene Monooxygenase Influence Catalysis
Authors: Vardar Gönül , Wood Thomas K.
Published: February 2005

Alpha-subunit position M180 of toluene-
o
-xylene monooxygenase influences the regiospecific oxidation of aromatics (e.g., from
o
-cresol, M180H forms 3-methylcatechol, methylhydroquinone, and 4-methylresorcinol, whereas the wild type forms only 3-methylcatechol). Position E214 influences the rate of reaction (e.g., E214G increases
p-
nitrophenol oxidation 15-fold) by controlling substrate entrance and product efflux as a gate residue.
SOS-Independent Induction ofdinBTranscription by β-Lactam-Mediated Inhibition of Cell Wall Synthesis inEscherichia coli
Authors: Pérez-Capilla Tatiana , Baquero María-Rosario , Gómez-Gómez José-María , Ionel Alina , Martín Soledad , Blázquez Jesús
Published: February 2005

Transcription of thedinBgene, encoding DNA polymerase IV, is induced by the inhibition of cell wall synthesis at different levels. Using the β-lactam antibiotic ceftazidime, a PBP3 inhibitor, as a model, we have shown that this induction is independent of the LexA/RecA regulatory system. Induction ofdinBtranscription mediated by ceftazidime produces an increase in the reversion of a +1 Lac frameshift mutation.
Mutational Alterations of the KeycisProline Residue That Cause Accumulation of Enzymatic Reaction Intermediates of DsbA, a Member of the Thioredoxin Superfamily
Authors: Kadokura Hiroshi , Nichols Lorenzo , Beckwith Jon
Published: February 2005

The DsbA-DsbB pathway introduces disulfide bonds into newly translocated proteins. Conversion of the conservedcisproline 151 of DsbA to several hydrophilic residues results in accumulation of mixed disulfides between DsbA and its dedicated oxidant, DsbB. However, only a proline-to-threonine change causes accumulation of mixed disulfides of DsbA with its substrates.
Identification of Genes Involved in the Glyoxylate Regeneration Cycle in
Methylobacterium extorquens
AM1, Including Two New Genes,
meaC
and
meaD
Authors: Korotkova Natalia , Lidstrom Mary E. , Chistoserdova Ludmila
Published: February 2005

The glyoxylate regeneration cycle (GRC) operates in serine cycle methylotrophs to effect the net conversion of acetyl coenzyme A to glyoxylate. Mutants have been generated in several genes involved in the GRC, and phenotypic analysis has been carried out to clarify their role in this cycle.
Contribution of the ATP Binding Site of ParE to Susceptibility to Novobiocin and Quinolones in
Streptococcus pneumoniae
Authors: Dupont Philippe , Aubry Alexandra , Cambau Emmanuelle , Gutmann Laurent
Published: February 2005

In
Streptococcus pneumoniae
, an H103Y substitution in the ATP binding site of the ParE subunit of topoisomerase IV was shown to confer quinolone resistance and hypersensitivity to novobiocin when associated with an S84F change in the A subunit of DNA gyrase. We reconstituted in vitro the wild-type topoisomerase IV and its ParE mutant. The ParE mutant enzyme showed a decreased activity for decatenation at subsaturating ATP levels and was more sensitive to inhibition by novobiocin but was as sensitive to quinolones. These results show that the ParE alteration H103Y alone is not responsible for quinolone resistance and agree with the assumption that it facilitates the open conformation of the ATP binding site that would lead to novobiocin hypersensitivity and to a higher requirement of ATP.
IMAGING SCATTERING MEDIA FROM A DISTANCE: THEORY AND APPLICATIONS OF NONCONTACT OPTICAL TOMOGRAPHY
Authors: RIPOLL JORGE , NTZIACHRISTOS VASILIS
Published: February 2005

Optical tomography of turbid media has been largely limited to systems that require fixed geometries or measurements employing fibers. Noncontact optical measurements from diffuse media could facilitate the use of large detector arrays at multiple angles that are well-suited for tomography applications. Such imaging strategies eliminate the need for individual fibers in contact with the highly scattering volume, the use of restricted geometries and the need for matching fluids. Here we review the different approaches and systems developed for noncontact optical measurements and concurrent registration of the three-dimensional surface information of the diffuse medium. We present the basic theoretical formulation and its experimental validation, finally applying it to the specific case of fluorescence tomography of small animals. We discuss how these new technologies can considerably simplify experimental procedures and improve our ability to visualize functional and molecular processes in vivo. Future perspectives and work are also outlined.
AN EXPERIMENTAL ANALYSIS OF THE RANDOMIZED PWM IN THE BOOST RECTIFIER
Authors: MIHALIC FRANC , MILANOVIC MIRO
Published: February 2005

Several recommendations and standards have increased the interest in power factor correction circuits. There are multiple solutions in which line current is sinusoidal and boost rectifier is one of them. In this paper an experimental analysis of the randomized pulse width modulation (RPWM) algorithm in the boost rectifier is performed. The influence of randomization is followed: first, introduction of the RPWM switching is reflected in smaller increase of the total harmonic distortion (THD) factor in the input current. Nevertheless, decrease of the power factor is negligibly small. Second, power spectrum density (PSD) of the input current is estimated and measured to evaluate the influence of the randomization in the high frequency range. Based on this approach, lower conductive electromagnetic interference (EMI) is expected and also experimentally verified.
USING INPUT INVARIANCE AS A METHOD TO FACILITATE SYSTEM DESIGN IN DPS APPLICATIONS
Authors: SUNTIO TEUVO , KOSTOV KONSTANTIN , TEPSA TAUNO , KYYRÄ JORMA
Published: February 2005

Distributed power supply (DPS) systems are extensively used to supply different electronic equipment and systems such as telecom switching systems. Continuous reduction of supply voltages of digital integrated circuits from the previous industry standard of 5 V down to 1 V or even less has necessitated the use of point-of-load system architectures due to high supply currents. The input currents of the switched-mode power supplies contain typically high ripple currents necessitating the use of noise suppression (EMI) filters to meet the stringent requirements stipulated by international standards. The interactions between the load converters, EMI filters, and supply side converters may adversely affect the stability and performance of the system. The system analysis is typically made based on the behavior of the ratio between the output impedance of the supply side and the input impedance of the load side known as minor-loop gain. Certain forbidden regions in the complex plane have been developed out of which the minor-loop gain should stay in order to guarantee stability. Even if the restrictions for the behavior of the minor-loop gain are well-defined, the accurate prediction of the associated impedances is difficult or even impossible. We propose, in this paper, a method based on input invariance to cancel the load-side interactions in the small-signal sense. The only concern left is then the stability of EMI filters, which may be considered based on the input power of the associated converters.
COMPONENT MINIMIZED TOPOLOGY OF DC TO THREE-PHASE INVERTER
Authors: MILANOVIC MIRO , MIHALIC FRANC , DOLINAR DRAGO
Published: February 2005

A DC to three-phase converter based on using a two-phase to three-phase transformation has been developed. To provide a better understanding of the operation principle, the transformer, which is the main element of the system, has been supplied by two single-phase inverters. According to this, the theoretical analysis of the proposed system is shown. This analysis is based on two-phase to three-phase transformation. The theoretical analysis and the experimental verification of the proposed principle are presented. In this paper the component minimized inverter topology is also proposed.
ENERGY FLOW CONTROL BETWEEN STATIC SERIES COMPENSATOR AND DISTRIBUTION SYSTEMS
Authors: AWAD HILMY , SVENSSON JAN , BOLLEN MATH H. J.
Published: February 2005

By proper control algorithms, the energy flow between the static series compensator (SSC) and the distribution system can be fully controlled. This paper proposes and describes two control techniques to exchange electric energy between the energy storage capacitor (ESC) of the SSC and the utility. The first is based on using a shunt diode rectifier, which is placed either on the load side or the grid side (both configurations are studied). The other exploits the voltage source converter of the SSC to charge its the ESC. A design guide for the dc-capacitor is given. The proposed techniques are validated by PSCAD/EMTDC simulation.
Ligand-Target Interactions: What Can We Learn from NMR?
Authors: Carlomagno Teresa
Published: February 2005

▪ Abstract  The conformation of the ligand in complex with a macromolecular target can be studied by nuclear magnetic resonance (NMR) in solution for both tightly and weakly forming complexes. In the weak binding regime (koff> 104Hz), the structure of the bound ligand is accessible also for very large complexes (>100 kDa), which are not amenable to NMR studies in the tight binding regime. Here I review the state-of-the-art NMR methodology used for screening ligands and for the structural investigation of bound ligand conformations, in both tight and weak binding regimes. The advantages and disadvantages of each approach are critically described. The NMR methodology used to investigate transiently forming complexes has expanded considerably in the past few years, opening new possibilities for a detailed description of ligand-target interactions. Novel methods for the determination of the bound ligand conformation, in particular transferred cross-correlated relaxation, are thoroughly reviewed, and their advantages with respect to established methodology are discussed, using the epothilone-tubulin complex as a primary example.
Ions and RNA Folding
Authors: Draper David E. , Grilley Dan , Soto Ana Maria
Published: February 2005

▪ Abstract  The problem of how ions influence the folding of RNA into specific tertiary structures is being addressed from both thermodynamic (by how much do different salts affect the free energy change of folding) and structural (how are ions arranged on or near an RNA and what kinds of environments do they occupy) points of view. The challenge is to link these different approaches in a theoretical framework that relates the energetics of ion-RNA interactions to the spatial distribution of ions. This review distinguishes three different kinds of ion environments that differ in the extent of direct ion-RNA contacts and the degree to which the ion hydration is perturbed, and summarizes the current understanding of the way each environment relates to the overall energetics of RNA folding.
ENDOCRINOLOGY OF THE STRESS RESPONSE
Authors: Charmandari Evangelia , Tsigos Constantine , Chrousos George
Published: February 2005

▪ Abstract  The stress response is subserved by the stress system, which is located both in the central nervous system and the periphery. The principal effectors of the stress system include corticotropin-releasing hormone (CRH); arginine vasopressin; the proopiomelanocortin-derived peptides α-melanocyte-stimulating hormone and β-endorphin, the glucocorticoids; and the catecholamines norepinephrine and epinephrine. Appropriate responsiveness of the stress system to stressors is a crucial prerequisite for a sense of well-being, adequate performance of tasks, and positive social interactions. By contrast, inappropriate responsiveness of the stress system may impair growth and development and may account for a number of endocrine, metabolic, autoimmune, and psychiatric disorders. The development and severity of these conditions primarily depend on the genetic vulnerability of the individual, the exposure to adverse environmental factors, and the timing of the stressful events, given that prenatal life, infancy, childhood, and adolescence are critical periods characterized by increased vulnerability to stressors.
Short-Term Treatment With Atorvastatin Reduces Platelet CD40 Ligand and Thrombin Generation in Hypercholesterolemic Patients
Authors: Sanguigni Valerio , Pignatelli Pasquale , Lenti Luisa , Ferro Domenico , Bellia Alfonso , Carnevale Roberto , Tesauro Manfredi , Sorge Roberto , Lauro Renato , Violi Francesco
Published: February 2005

Background—

Soluble CD40L (sCD40L), a substance that maximally reflects in vivo platelet activation, is increased in patients with hypercholesterolemia. We investigated the relation between sCD40L and platelet CD4OL in hypercholesterolemic patients before and after a short-term treatment with atorvastatin.

Methods and Results—

Collagen-induced platelet CD40L and plasma levels of sCD40L and prothrombin fragment F1+2, a marker of thrombin generation, were investigated in 30 hypercholesterolemic patients and 20 healthy subjects. Hypercholesterolemic patients were then randomized to either diet (n=15; group A) or atorvastatin 10 mg/d (group B); the aforementioned variables were measured at baseline and after 3 days of treatment. Compared with referents, hypercholesterolemic patients showed higher values of platelet CD40L (
P
<0.005), sCD40L (
P
<0.005), and F1+2 (
P
<0.003). Platelet CD40L was significantly correlated with sCD40L (
P
<0.001), and the latter was significantly correlated with F1+2 (
P
<0.001). The intervention trial showed no changes in group A but a significant decrease in platelet CD40L (
P
<0.01), sCD40L (
P
<0.002), and F1+2 (
P
<0.03) in group B. In vitro studies demonstrated that cholesterol enhanced platelet CD40L and CD40L-mediated clotting activation by human monocytes; also, atorvastatin dose-dependently inhibited platelet CD40L expression and clotting activation by CD40L-stimulated monocytes.

Conclusions—

This study shows that, in hypercholesterolemia, platelet overexpression of CD40L may account for enhanced plasma levels of sCD40L and F1+2. Atorvastatin exerts a direct antithrombotic effect via inhibition of platelet CD40L and CD40L-mediated thrombin generation, independently of its cholesterol-lowering effect.
Injectable Self-Assembling Peptide Nanofibers Create Intramyocardial Microenvironments for Endothelial Cells
Authors: Davis Michael E. , Motion J.P. Michael , Narmoneva Daria A. , Takahashi Tomosaburo , Hakuno Daihiko , Kamm Roger D. , Zhang Shuguang , Lee Richard T.
Published: February 2005

Background—

Promoting survival of transplanted cells or endogenous precursors is an important goal. We hypothesized that a novel approach to promote vascularization would be to create injectable microenvironments within the myocardium that recruit endothelial cells and promote their survival and organization.

Methods and Results—

In this study we demonstrate that self-assembling peptides can be injected and that the resulting nanofiber microenvironments are readily detectable within the myocardium. Furthermore, the self-assembling peptide nanofiber microenvironments recruit progenitor cells that express endothelial markers, as determined by staining with isolectin and for the endothelial-specific protein platelet–endothelial cell adhesion molecule-1. Vascular smooth muscle cells are recruited to the microenvironment and appear to form functional vascular structures. After the endothelial cell population, cells that express α-sarcomeric actin and the transcription factor Nkx2.5 infiltrate the peptide microenvironment. When exogenous donor green fluorescent protein–positive neonatal cardiomyocytes were injected with the self-assembling peptides, transplanted cardiomyocytes in the peptide microenvironment survived and also augmented endogenous cell recruitment.

Conclusions—

These experiments demonstrate that self-assembling peptides can create nanofiber microenvironments in the myocardium and that these microenvironments promote vascular cell recruitment. Because these peptide nanofibers may be modified in a variety of ways, this approach may enable injectable tissue regeneration strategies.
Policy Learning, Policy Diffusion, and the Making of a New Order
Authors: Meseguer Covadonga
Published: February 2005

This article surveys the role of learning as mechanism of policy diffusion in the context of the creation of a new political order. The author discusses policy learning against the background of recent research on the diffusion of deregulatory and regulatory policies and attempts to distinguish learning from other mechanisms of diffusion. She then surveys the challenges entailed in testing this mechanism and sets out her particular approach: a rational version of learning. She also reports the results of preliminary efforts to test learning as applied to the diffusion of regulatory policies. The author concludes that learning cannot be rejected as a plausible mechanism of the diffusion of policies, although it shares its explanatory role with less rational mechanisms of diffusion, in particular policy emulation. Further research and analysis is needed to test learning in either its rational or its bounded version and, in doing so, to delve into the politics of learning.
Uncope: A Screen for Substance Dependence among State Prison Inmates
Authors: Campbell Todd C. , Hoffmann Norman G. , Hoffmann Tyson D. , Gillaspy J. Arthur
Published: February 2005

Efficient and accurate screening for alcohol and other drug dependences is critical if addictions are to be addressed in correctional populations. The UNCOPE, a six-item screen developed on clinical and corrections populations, was evaluated for accuracy in a state inmate population. Results using receiver operating characteristics calculated the overall expected accuracy of the UNCOPE to approach 0.90, with 1.0 being a perfect prediction. The UNCOPE performed comparably on gender and ethnic subgroups as well as subgroups identified by education level. The findings suggest that the UNCOPE could be an effective aid in identifying treatment needs among state prison inmates.
Outcomes of Mandated and Nonmandated New York City Jail Diversion for Offenders with Alcohol, Drug, and Mental Disorders
Authors: Broner Nahama , Mayrl Damon W. , Landsberg Gerald
Published: February 2005

The authors studied 175 mentally ill, substance-using adult jail detainees assessed at baseline, 3, and 12 months through a quasi-experimental comparison design. The study examines the effect of diversion, treatment, and individual characteristics on criminal justice, mental health, substance use, and life satisfaction outcomes. The intervention group included nonmandated and mandated diversion tracks. The comparison participants met diversion acceptance criteria but underwent standard criminal justice processes. Main findings included that mandated diversion clients were less likely to spend as much time in prison and more likely to spend time in the community, have been linked to residential and outpatient treatment, have received more treatment, and decrease drug use. However, those who did not perceive themselves coerced and had insight into their mental illness received more treatment regardless of diversion condition. Although mandated diversion was found effective for some outcomes, individual characteristics, treatment, and diversion in general significantly contributed.
Lifetime Health Services Use by Male Drug-Abusing Offenders
Authors: Webster J. Matthew , Leukefeld Carl G. , Tindall Michele Staton , Hiller Matthew L. , Garrity Thomas F. , Narevic Egle
Published: February 2005

A modified version of the Andersen and Newman model of health services use was used to examine how male drug-abusing offenders use health services during their lifetimes. Hierarchical regression models were employed to determine the extent to which (a) sociodemographic information, (b) drug use and criminal history, and (c) illness-level factors were predictive of the use of these services. In general, these models explained a moderate level of the variance in services use, with illness-level factors accounting for the majority of variance. Implications for health services in criminal justice settings are discussed.
Cognitive Markers of Adolescent Risk Taking: A Correlate of Drug Abuse in At-Risk Individuals
Authors: Rosser Rosemary , Stevens Sally , Ruiz Bridget
Published: February 2005

Behavioral traits associated with adolescent risk taking may be correlated with maturational events occurring in the brain. Adolescent brains are less developed than previously believed, particularly in prefrontal cortex, a region implicated in moderating behavior related to drug use. One indictor used to assess frontal lobe functioning is the Tower of Hanoi. The authors compared substance-involved adolescents with a control group of resilient youth on their Tower of Hanoi performance and detected significantly different error patterns across the two groups. Resilient youths made fewer moves and spent more time per move; their substance-involved counterparts made more moves and spent less time per move, a strategy that could be construed as impulsive.
Treatment Issues and Outcomes for Juvenile-Justice-Involved Youth from Rural and Nonrural Areas
Authors: Ruiz Bridget S. , Stevens Sally J. , McKnight Katherine , Godley Susan H. , Shane Patricia
Published: February 2005

Research findings from the past 15 years indicate that drug use and mental health problems among adolescents from rural areas of the United States have equaled or exceeded those of nonrural youth. These comparisons, however, have typically been made on community samples, leaving a gap in knowledge regarding rural versus nonrural youth enrolled in substance abuse treatment. To address this gap in research, this study examines differences between juvenile-justice-involved rural and nonrural adolescents enrolled in drug treatment on substance abuse and mental health problems at treatment entry and at 3, 6, 12, and 30 months following treatment entry.
Treadmills of Production and Destruction
Authors: Hooks Gregory , Smith Chad L.
Published: February 2005

The treadmill of production has identified and examined an inherent dynamic that results in the inexorable expansion of capitalism. Although it is argued that a number of benefits accompany this economic expansion, the treadmill of production literature has focused on the environmental costs. The treadmill of production embraces the legacy of C. Wright Mills with a focus on the entangled relationships between two aspects of Mills’s “power elite”—politics and economics. Building on Mills’s inclusion of militarism as one of the three pillars of the power elite, it is argued that there exists a treadmill of destruction that maintains a distinct logic relating to geopolitics and arms races that cannot be reduced to capitalism. The 20th century has witnessed unprecedented growth in the research, testing, storage, and employment of both conventional weaponry and weapons of mass destruction. In focusing on this development, the distinctive role the state plays in creating a treadmill of destruction is stressed.
Treadmill Politics, Information Politics, and Public Policy
Authors: Overdevest Christine
Published: February 2005

Here, the author reviews arguments about the uses of collaborative and performance-based information in environmental politics. The use of information is considered as a way to transform treadmill politics. In particular, recent experiments in participatory forest standard setting and certification operate to generate information about forest practice and policy for interested parties. The case that environmental nongovernmental organizations (NGOs) or other civil society groups armed with collaborative and performance-based information can push more effectively for social change is considered, as is the role of the state in (potentially) fostering information provision as public policy. Results presented here follow the completion of 40 interviews with certification actors in the United States, archival research on key documents, analysis of transcripts of industry and NGO conferences on certification, and field tours with managers of certified lands.
Prolastin, a pharmaceutical preparation of purified human α1-antitrypsin, blocks endotoxin-mediated cytokine release
Authors: Nita Izabela , Hollander Camilla , Westin Ulla , Janciauskiene Sabina-Marija
Published: February 2005

Background

α1-antitrypsin (AAT) serves primarily as an inhibitor of the elastin degrading proteases, neutrophil elastase and proteinase 3. There is ample clinical evidence that inherited severe AAT deficiency predisposes to chronic obstructive pulmonary disease. Augmentation therapy for AAT deficiency has been available for many years, but to date no sufficient data exist to demonstrate its efficacy. There is increasing evidence that AAT is able to exert effects other than protease inhibition. We investigated whether Prolastin, a preparation of purified pooled human AAT used for augmentation therapy, exhibits anti-bacterial effects.

Methods

Human monocytes and neutrophils were isolated from buffy coats or whole peripheral blood by the Ficoll-Hypaque procedure. Cells were stimulated with lipopolysaccharide (LPS) or zymosan, either alone or in combination with Prolastin, native AAT or polymerised AAT for 18 h, and analysed to determine the release of TNFα, IL-1β and IL-8. At 2-week intervals, seven subjects were submitted to a nasal challenge with sterile saline, LPS (25 μg) and LPS-Prolastin combination. The concentration of IL-8 was analysed in nasal lavages performed before, and 2, 6 and 24 h after the challenge.

Results

In vitro, Prolastin showed a concentration-dependent (0.5 to 16 mg/ml) inhibition of endotoxin-stimulated TNFα and IL-1β release from monocytes and IL-8 release from neutrophils. At 8 and 16 mg/ml the inhibitory effects of Prolastin appeared to be maximal for neutrophil IL-8 release (5.3-fold, p < 0.001 compared to zymosan treated cells) and monocyte TNFα and IL-1β release (10.7- and 7.3-fold, p < 0.001, respectively, compared to LPS treated cells). Furthermore, Prolastin (2.5 mg per nostril) significantly inhibited nasal IL-8 release in response to pure LPS challenge.

Conclusion

Our data demonstrate for the first time that Prolastin inhibits bacterial endotoxin-induced pro-inflammatory responses in vitro and in vivo, and provide scientific bases to explore new Prolastin-based therapies for individuals with inherited AAT deficiency, but also for other clinical conditions.
Transient expression analysis of allelic variants of a VNTR in the dopamine transporter gene (DAT1)
Authors: Mill Jonathan , Asherson Philip , Craig Ian , D'Souza Ursula M
Published: February 2005

Background

The 10-repeat allele of a variable number tandem repeat (VNTR) polymorphism in the 3'-untranslated region of the dopamine transporter gene (DAT1) has been associated with a range of psychiatric phenotypes, most notably attention-deficit hyperactivity disorder. The mechanism for this association is not yet understood, although several lines of evidence implicate variation in gene expression. In this study we have characterised the genomic structure of the 9- and 10-repeat VNTR alleles, and directly examined the role of the polymorphism in mediating gene expression by measuring comparative in vitro cellular expression using a reporter-gene assay system.

Results

Differences in the sequence of the 9- and 10- repeat alleles were confirmed but no polymorphic differences were observed between individuals. There was no difference in expression of reporter gene constructs containing the two alleles.

Conclusions

Our data suggests that this VNTR polymorphism may not have a direct effect on DAT1 expression and that the associations observed with psychiatric phenotypes may be mediated via linkage disequilibrium with other functional polymorphisms.
Hesperidin, a citrus bioflavonoid, decreases the oxidative stress produced by carbon tetrachloride in rat liver and kidney
Authors: Tirkey Naveen , Pilkhwal Sangeeta , Kuhad Anurag , Chopra Kanwaljit
Published: February 2005

Background

CCl4 is a well-established hepatotoxin inducing liver injury by producing free radicals. Exposure to CCl4 also induces acute and chronic renal injuries. The present study was designed to establish the protective effect of hesperidin (HDN), a citrus bioflavonoid, on CCl4-induced oxidative stress and resultant dysfunction of rat liver and kidney.

Methods

Animals were pretreated with HDN (100 and 200 mg/kg orally) for one week and then challenged with CCl4 (2 ml/kg/s.c.) in olive oil. Rats were sacrificed by carotid bleeding under ether anesthesia. Liver enzymes, urea and creatinine were estimated in serum. Oxidative stress in liver and kidney tissue was estimated using Thiobarbituric acid reactive substances (TBARS), glutathione (GSH) content, superoxide dismutase(SOD), and Catalase (CAT)

Results

CCl4 caused a marked rise in serum levels of ALT and AST (P < 0.05). TBARS levels were significantly increased whereas GSH, SOD and CAT levels decreased in the liver and kidney homogenates of CCl4 treated rats. HDN (200 mg/kg) successfully attenuated these effects of CCl4

Conclusion

In conclusion, our study demonstrated a protective effect of HDN in CCl4 induced oxidative stress in rat liver and kidney. This protective effect of HDN can be correlated to its direct antioxidant effect.