bluuebunny/crossref_metadata_2025_split huggingface dataset:
Attenuation to Control Gene Expression
Authors: Babitzke Paul , Gollnick Paul 
Published: March 2008

AbstractBacteria use a variety of strategies to regulate transcription elongation in response to changes in their environment. Several of these regulatory events are classified as transcription attenuation mechanisms, which involve regulated transcription termination to control expression of downstream genes. In most cases, two alternative RNA secondary structures, an antiterminator and an intrinsic terminator, share nucleotides in common such that their formation is mutually exclusive. Thus, the level of expression of the downstream genes depends on the frequency that the antiterminator forms in the nascent transcript. Transcription attenuation mechanisms in general are separated into two categories. The first category involves situations in which the action of a regulatory molecule promotes transcription termination, with the default situation being transcription readthrough. The second category involves situations in which the action of the regulatory molecule promotes transcription readthrough (antitermination), with the default situation being transcription termination. Transcription attenuation controls the expression of several amino acid biosynthetic and catabolic operons. These mechanisms are often controlled by the efficiency of leader peptide synthesis in Gram‐negative bacteria, whereas Gram‐positive organisms often use RNA binding proteins or tRNA molecules to determine whether the RNA will fold into the antiterminator or terminator structures. Several examples of transcription attenuation also exist in which an antisense RNA is responsible for controlling plasmid copy number. In addition, small metabolites participate in transcription attenuation mechanisms of a wide variety of bacterial genes by binding directly to the nascent transcript.
Lysosomal Disorders
Authors: Brooks Doug A. , Fuller Maria 
Published: March 2008

Abstract
Lysosomal storage disorders are a group of over 50 different genetic diseases that result from lysosomal dysfunction. This disruption of lysosomal function can involve either a specific lysosomal hydrolase deficiency, a defect in lysosomal protein processing, or impaired lysosomal biogenesis. To appreciate the pathogenesis of lysosomal disorders fully, it is important to understand the dynamics of endosome–lysosome organelles, their capacity for the uptake and degradation of complex macromolecules, and how lysosomal biogenesis and hydrolysis are altered by substrate storage. The focus of this article will be on recognized lysosomal disorders and what is known about the composition and the function of endosome–lysosome organelles in these diseases. The lysosomal network will be discussed with a view to correlating the main site of endosome–lysosome degradation and the site of substrate accumulation in lysosomal disorders. A major unanswered question for lysosomal storage disorders is how an enzyme deficiency and the resulting storage of undegraded macromolecules impact on cells to cause organ dysfunction and disease.
Membrane Fluidity
Authors: Dzikovski Boris , Freed Jack H. 
Published: March 2008

AbstractIn the popular fluid mosaic model for biomembranes, membrane proteins and other membrane‐embedded molecules are in a two‐dimensional fluid formed by the phospholipids. Such a fluid state allows free motion of constituents within the membrane bilayer and is extremely important for membrane function. The term “membrane fluidity” is a general concept, which refers to the ease of motion for molecules in the highly anisotropic membrane environment. We give a brief description of physical parameters associated with membrane fluidity, such as rotational and translational diffusion rates, order parameters etc., and review physical methods used for their determination. We also show limitations of the fluid mosaic model and discuss recent developments in membrane science that pertain to fluidity, such as evidence for compartmentalization of the biomembrane by the cell cytoskeleton.
Mitogen‐activated Protein Kinases (
MAPKs
):
ERKs
,
JNKs
, and
p
38
s
Authors: Chen Wei , Juang Yu‐Chi , Cobb Melanie 
Published: March 2008

Abstract
Mitogen‐activated protein kinases (MAPKs) are significant mediators in signal transduction pathways from the membrane to intracellular compartments including the nucleus. They regulate the functions of many gene products and therefore affect cell growth, differentiation, and death. Three main MAPK subfamilies have been identified and are studied widely. All function in cascades that include at least three tiers of protein kinases. Selective kinase inhibitors have been developed; they are powerful tools to study the physiologic functions of MAPKs and, in some cases, are promising and effective drugs. In this article, the regulation of the three main MAPK pathways is sketched, and the status of MAPK inhibitors and their inhibiting mechanisms are highlighted.
Mathematical Modelling of Biological Signaling Networks
Authors: Haugh Jason M. 
Published: March 2008

AbstractIntracellular signaling networks, which are composed of interconnected biochemical pathways, regulate and actuate responses such as cell‐cycle progression and cell migration, survival, and differentiation. Although our knowledge of the intricate biochemical mechanisms at the level of individual proteins and molecular interactions is ever expanding, those details leave us with an even murkier view of how the complex network operates as a whole. True understanding requires knowing not only what happens at the molecular level but also how these mechanisms influence the precise magnitude, timing, and spatial localization of signal transduction processes. Hence, mathematical modeling and analysis has emerged in recent years as a legitimate approach for interpreting experimental results and generating novel hypotheses for additional study and model refinement. Once conducted in isolation and scorned by most biologists, quantitative modeling has moved into the mainstream as a powerful tool for the analysis of cell signaling. In this article, the biological, chemical, and physical underpinnings of this approach are presented, as are its current applications and future challenges.
Terpenoids in Plant Signaling: Chemical Ecology
Authors: Kappers Iris F. , Dicke Marcel , Bouwmeester Harro J. 
Published: March 2008

Abstract
Terpenoids constitute the largest class of secondary metabolites in the plant kingdom. Because of their immense structural diversity and the resulting diversity in physiochemical properties, these molecules are particularly important for plant communication with other organisms. In this article, we will describe the ecological significance of terpenoids for plants, how terpenoid formation is regulated, and the tools we have to improve our understanding of the role of terpenoids in plant ecology and to create crop plants with improved resistance.
Triplex Formation by Pyrene‐Labelled Probes for Nucleic Acid Detection in Fluorescence Assays
Authors: Van Daele Ineke , Bomholt Niels , Filichev Vyacheslav V. , Van Calenbergh Serge , Pedersen Erik B. 
Published: March 2008

AbstractTriplex‐forming homopyrimidine oligonucleotides containing insertions of a 2′–5′ uridine linkage featuring a pyrene moiety at the 3′‐position exhibit strong fluorescence enhancement upon binding to double‐stranded DNA through Hoogsteen base pairing. It is shown that perfect matching of the new modification to the base pair in the duplex is a prerequisite for strong fluorescence, thus offering the potential to detect single mutations in purine stretches of duplex DNA. The increase in the fluorescence signal was dependent on the thermal stability of the parallel triplex, so a reduction in the pH from 6.0 to 5.0 resulted in an increase in thermal stability from 25.0 to 55.0 °C and in an increase in the fluorescence quantum yield (ΦF) from 0.061 to 0.179, while the probe alone was fluorescently silent (ΦF=0.001–0.004). To achieve higher triplex stability, five nucleobases in a 14‐mer sequence were substituted with α‐L‐LNA monomers, which provided a triplex with a Tm of 49.5 °C and a ΦF of 0.158 at pH 6.0. Under similar conditions, a Watson–Crick‐type duplex formed with the latter probe showed lower fluorescence intensity (ΦF=0.081) than for the triplex.
Identification, Synthesis, and Enzymology of Non‐natural Glucosinolate Chemopreventive Candidates
Authors: Mays Jared R. , Weller Roska Rachel L. , Sarfaraz Sami , Mukhtar Hasan , Rajski Scott R. 
Published: March 2008

AbstractIsothiocyanates (ITCs) are one of the many classes of breakdown products of glucosinolates found in crucifers such as broccoli and are thought to be partially responsible for the reduced risk of degenerative diseases associated with the consumption of vegetables. The production of ITCs such as L‐sulforaphane is dependent on the hydrolytic bioactivities of myrosinase, localized both within vegetable tissues and within flora of the human GI tract, and is associated with important cancer chemopreventive activities. We hypothesized that novel isothiocyanates with enhanced chemopreventive properties relative to L‐sulforaphane could be identified and that their glucosinolate precursors could be synthesized. From a library of 30 synthetic ITCs, we identified several with bioactivities equal or superior to those of L‐sulforaphane. The corresponding non‐natural glucosinolate precursors to these novel ITCs were constructed and found to be substrates for myrosinase. By utilizing a novel RP‐HPLC assay to monitor myrosinase‐dependent hydrolysis reactions, 2,2‐diphenylethyl glucosinolate and (biphenyl‐2‐yl)methyl glucosinolate were shown to exhibit 26.5 and 2.8 %, respectively, of the relative activity of sinigrin and produced their corresponding ITCs in varying yields. These data support the notion that non‐natural glucosinolates can act as prodrugs for novel ITCs, with a mechanism of action reliant on their hydrolytic cleavage by myrosinase. Such non‐natural glucosinolates may serve as very economical chemopreventive agents for individuals at risk for cancers of and around the GI tract.
Complexation and Fluorescence of Tricyclic Basic Dyes Encapsulated in Cucurbiturils
Authors: Montes‐Navajas Pedro , Corma Avelino , Garcia Hermenegildo 
Published: March 2008

AbstractTricyclic basic dyes (proflavine, acridine orange, pyronine, pyronine Y, oxonine, thionine and methylene blue) often form one‐to‐one or two‐to‐one complexes with CB[7] and CB[8], respectively. In the case of pyronine Y, the complexes with CB[7] and CB[8] have a one‐to‐one and three‐to‐one stoichiometry, respectively. The binding constants for CB[7] complexes range from 3.07×106 to 1.70×107 m−1. In the case of CB[8], the association constant varies between 3.24×1013 and 2.50×1016 m−2. Overall, these binding constants are four orders of magnitude higher than those reported for the same dyes in β and γ‐cyclodextrins. Formation of the host–guest complexes leads to an increase in the fluorescence quantum yields in the case of CB[7], while the dimeric or trimeric dye encapsulated in CB[8] are remarkably less fluorescent than the same dye in diluted solutions.
Synthesis, Characterization, Spectroscopic and Photophysical Properties of New [Cu(NCS){(L‐N)2 or (L′‐NN)}(PPh3)] Complexes (L‐N, L′‐NN = Aromatic Nitrogen Base)
Authors: Pettinari Claudio , di Nicola Corrado , Marchetti Fabio , Pettinari Riccardo , Skelton Brian W. , Somers Neil , White Allan H. , Robinson Ward T. , Chierotti Michele R. , Gobetto Roberto , Nervi Carlo 
Published: March 2008

AbstractThe syntheses, spectroscopic characterization (IR, 1H and 31P NMR, ESI‐MS) and conductivity studies of the mixed N,P‐donor complexes of copper(I) thiocyanate: [Cu(NCS)(py)2(PPh3)], (2), [Cu(NCS)(Mepy)(PPh3)]2, (3), [Cu(NCS)(phen)(PPh3)], (4), [Cu(NCS)(bpy)(PPh3)], (5), [Cu(NCS)(bpy)(PPh2py)], (6), [Cu(NCS)(py)(PPh2py)], (7), (py = pyridine; Mepy = 2‐methylpyridine; phen = 1,10‐phenanthroline, bpy = 2,2′‐bipyridyl), together with single‐crystal X‐ray structural characterizations of 2, 3, 4 (new polymorph), 5 and 6 are reported, which provides an opportunity to study the effect of the introduction of a pair of nitrogen donors, both unidentate and chelate, on the bonding parameters of the Cu/NCS/P system. Cu–P and Cu–N2(ar) are found to be similar [2.1974(5) and 2.091(2), 2.070(1) Å for py2 adduct 2, cf. 2.1748(9)–2.200(1) and 2.071(2)–2.106(4) Å for the counterpart values for bidentate adducts 4–6]. However, Cu–N(CS) and Cu–N–C are 2.013(2) Å and 157.4(2)° for py2 adduct 2 and 1.946(2)–1.981(8) Å and 166.7(2)–176.58(2)° for bidentate counterparts 4–6. The change is attributed primarily to the closure in the N–Cu–N angle [99.58(8)° for py2 2; 77.7(6)–80.5(3)° for N∧N‐bidentate donors 4–6]. In consequence of the increased steric profile of the Mepy ligand, we find the stoichiometry diminished to 1:1:1, which resulted in theformation of [(Ph3P)MepyCu(SCNNCS)Cu(Mepy)(PPh3)] dimers.TDDFT/CPCM calculations were used to clarify the type of transitions involved in the UV/Vis absorption spectra, and the corresponding experimental photoemission data wereacquired. The 31P CPMAS spectra of the copper derivatives exhibit distorted quartets that afford values for 1JCu,P. Furthermore, the quadrupole‐induced distortion factors were calculated, and in the cases of 2, 4 and 5, the quadrupole coupling constants were obtained, on the basis of the X‐ray structures.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Self‐Assembly of p‐Sulfonatocalix[4]arene and a Ag–hmt Coordination Polymer into a Porous Structure
Authors: Zheng Guo‐li , Zhang Hong‐Jie , Song Shu‐Yan , Li Yin‐Yan , Guo Hua‐Dong 
Published: March 2008

AbstractA novel porous material constructed from p‐sulfonatocalix[4]arene molecules and a AgI coordination polymer has been structurally characterized. The porous supramolecular complex features a bilayer arrangement of p‐sulfonatocalix[4]arene molecules linked by a AgI–hmt (hmt: hexamethylenetetramine) coordination polymer through metal–ligand bonding, hydrogen bonding and host–guest interactions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Differential Pulse Voltammetric Determination of Uric Acid on Carbon‐Coated Iron Nanoparticle Modified Glassy Carbon Electrodes
Authors: Wang Shengfu , Xu Qiao , Liu Guodong 
Published: March 2008

AbstractA carbon‐coated iron nanoparticles (CIN, a new style fullerence related nanomaterial) modified glassy carbon electrode (CIN/GCE) has been developed for the determination of uric acid (UA). Electrochemical behaviors of UA on CIN/GCE were explored by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that the voltammetric response of UA on CIN/GC was enhanced dramatically because of the strong accumulation effect of CIN and the large working area of the CIN/GC electrode. The parameters including the pH of supporting electrolyte, accumulation potential and time, that govern the analytical performance of UA have been studied and optimized. The DPV signal of UA on CIN/GCE increased linearly with its concentration in the range from 5.0×10−7 to 2.0×10−5 M, with a detection limit of 1.5×10−7 M (S/N=3). The CIN/GCE was used for the determination of UA in samples with satisfactory results. The proposed CIN/GCE electrochemical sensing platform holds great promise for simple, rapid, and accurate detection of UA.
Patterns of cerebral activation during olfactory and trigeminal stimulations
Authors: Lombion Sandrine , Comte Alexandre , Tatu Laurent , Brand Gérard , Moulin Thierry , Millot Jean‐Louis 
Published: March 2008

AbstractIt is well known that most odorants stimulate both the olfactory system and the trigeminal system. However, the overlap between the brain processes involved in each of these sensorial perceptions is still poorly documented. This study aims to compare fMRI brain activations while smelling two odorants of a similar perceived intensity and pleasantness: phenyl ethyl alcohol (a pure olfactory stimulus) and iso‐amyl‐acetate (a bimodal olfactory‐trigeminal stimulus) in a homogeneous sample of 15 healthy, right‐handed female subjects. The analysis deals with the contrasts of brain activation patterns between these two odorant conditions. The results showed a significant recruitment of the right insular cortex, and bilaterally in the cingulate in response to the trigeminal component. These findings are discussed in relation to the characteristics of these odorants compared with those tested in previous studies. Hum Brain Mapp, 2009. © 2008 Wiley‐Liss, Inc.
Cell autonomous function of nogo and reticulons: The emerging story at the endoplasmic reticulum
Authors: Teng Felicia Yu Hsuan , Tang Bor Luen 
Published: March 2008

AbstractThe myelin‐associated membrane protein reticulon‐4 (RTN4)/Nogo has been extensively studied with regards to its neurite outgrowth inhibitory function, both in limiting plasticity in the healthy adult brain and regeneration during central nervous system injury. These activities are presumably associated with Nogo splice isoforms expressed on the cell surface and function largely in trans, exerting an influence as an intercellular membrane‐bound ligand. Nogo, and other reticulon paralogues and orthologues, are however mainly localized to the endoplasmic reticulum (ER), and are likely to have cell autonomous functions that are not yet clear. Emerging evidence suggests that Nogo may have a role in modulating the morphology and functions of the ER. This role is apparently not essential for cell viability under normal growth conditions, but may be manifested under certain stress conditions. J. Cell. Physiol. 216: 303–308, 2008. © 2008 Wiley‐Liss, Inc.
Developing and testing a measure for the ethical culture of organizations: the corporate ethical virtues model
Authors: Kaptein Muel 
Published: March 2008

AbstractBased on four interlocking empirical studies, this paper initially validates and refines the Corporate Ethical Virtues Model which formulates normative criteria for the ethical culture of organizations. The findings of an exploratory factor analysis provide support for the existence of eight unidimensional subscales: clarity, congruency of supervisors, congruency of management, feasibility, supportability, transparency, discussability, and sanctionability. The findings of a confirmatory factor analysis show that the overall fit of the model is quite high. Evidence of convergent and discriminant validity is also found. The resulting 58‐item self‐reporting questionnaire is a useful tool that can be used in future research and by managers in assessing the ethical culture of their organization. Copyright © 2008 John Wiley & Sons, Ltd.
Character in organizational research: past directions and future prospects
Authors: Wright Thomas A. , Huang Ching‐Chu 
Published: March 2008

AbstractCharacter (ethos) refers to those interpenetrable habitual qualities within individuals, and applicable to organizations that both constrain and lead them to desire and pursue personal and societal good. In our Incubator article, we undertake two objectives. First, we provide our conceptualization of character; briefly specifying what character is and is not. Second, we introduce several promising directions for organizationally based research on character. Copyright © 2008 John Wiley & Sons, Ltd.
The effect of cold trap adsorbents on the gas chromatographic analysis of ambient VOCs under Peltier cooling conditions
Authors: Pal Raktim , Kim Ki‐Hyun 
Published: March 2008

AbstractIn this work, the relative analytical performance of the GC‐based detection method was investigated with a major focus on cold trap (CT) adsorbent materials against four aromatic volatile organic compounds (VOCs) (e. g., benzene, toluene, xylene, and styrene). A series of calibration experiments were hence conducted under cryofocusing conditions formed by the Peltier cooling system in a thermal desorber (TD) unit. During the course of this study, comparative calibration datasets were acquired for each of the three CT types: (i) CT (I) = Carbopack B + Carbopack C, (ii) CT (II) = Carbopack B + Carboxen 1000, and (iii) CT (III) = Tenax TA. All calibration datasets were obtained under subambient temperature (–10°C) conditions controlled by the Peltier cooling system. The reliability of the calibration data was also assessed in an ancillary experiment with the aid of the modified injection through a thermal desorber (MITD) method. The results demonstrated that the GC detection properties of different VOCs were not altered significantly between different CT applications under Peltier conditions, although relative sensitivity could be distinguished moderately depending on the CT type.
Thermal dimerization kinetics of 3‐(p‐bromo‐phenyl)‐pyridazinium benzoyl methylid in solutions
Authors: Melnig V. , Humelnicu I. , Dorohoi D. O. 
Published: March 2008

Abstract3‐(p‐Bromo‐phenyl)‐pyridazinium‐benzoyl methylid (BPPBM) participates in solution at 3 + 3 dipolar thermal dimerization that can be spectrally monitored by the extinction in its visible intramolecular charge transfer (ICT) band. The attenuation of ICT band intensity shows the decrease of the BPPBM concentration with the increasing of dimer concentration. The complex kinetics of light‐assisted dimerization process was studied taking into account that the thermodynamic equilibrium is reached after more than 24 h. On the basis of general order of reaction theory, we found that the dimerization reaction must be described as a multistep mechanism. The rate constants of the dimerization reactions in ethanol (k = 0.00897 s−1) and benzene (k = 0.00774 s−1) solutions were correlated with the BPPBM and dimer structural features established by using the HyperChem 5.02 simulation program package. A kinetic mechanism of 3 + 3 dipolar thermal dimerization for the studied ylid is proposed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 230–239, 2008
Temperature‐dependent kinetics study of the gas‐phase reactions of atomic chlorine with acetone, 2‐butanone, and 3‐pentanone
Authors: Zhao Z. , Huskey D. T. , Nicovich J. M. , Wine P. H. 
Published: March 2008

AbstractA laser flash photolysis–resonance fluorescence technique has been employed to study the kinetics of the reactions of atomic chlorine with acetone (CH3C(O)CH3; k1), 2‐butanone (C2H5C(O)CH3; k2), and 3‐pentanone (C2H5C(O)C2H5; k3) as a function of temperature (210–440 K) and pressure (30–300 Torr N2). No significant pressure dependence is observed for any of the reactions studied. Arrhenius expressions (units are 10−11 cm3 molecule−1 s−1) obtained from the data are k1(T) = (1.53 ± 0.19) exp[(−594 ± 33)/T], k2(T) = (2.77 ± 0.33) exp[(+76 ± 33)/T], and k3(T) = (5.66 ± 0.41) exp[(+87 ± 22)/T], where uncertainties are 2σ and represent precision only. The accuracy of reported rate coefficients is estimated to be ±15% over the entire range of pressure and temperature investigated. The room temperature rate coefficients reported in this study are in good agreement with a majority of literature values. However, the activation energies reported in this study are in poor agreement with the literature values, particularly for 2‐butanone and 3‐pentanone. Possible explanations for discrepancies in published kinetic parameters are proposed, and the potential role of Cl + ketone reactions in atmospheric chemistry is discussed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 259–267, 2008
On the 𝔉‐hypercentre of a finite group
Authors: Ballester–Bolinches Adolfo , Soler–Escrivà Xaro 
Published: March 2008

AbstractThe main objective of this paper is to study and describe the hypercentre of a finite group associated with saturated formations, in terms of some subgroup embedding properties related to permutability. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)