bluuebunny/crossref_metadata_2025 huggingface dataset:
Solvation of ions by dipolar aprotic solvents and water. A CNDO/2 study
Authors: Kyselka Petr , Havlas Zdeněk , Sláma Ivo
Published: September 2010

Solvation of Li+, Be2+, Na+, Mg2+, and Al3+ ions has been studied in binary mixtures with dimethyl sulphoxide, dimethylformamide, acetonitrile and water, and in ternary mixtures of the organic solvents with water. The CNDO/2 quantum chemical method was used to calculate the energies of solvation, molecular structures and charge distributions for the complexes acetonitrile...ion (1:1, 2:1, 4:1), dimethyl sulphoxide...ion (1:1), dimethylformamide...ion (1:1), and acetonitrile (dimethyl sulphoxide, dimethylformamide)...ion...water (1:1:1).
Surface behaviour of tetrapropylammonium cation at the mercury/solution interface measured by use of controlled convective adsorptive accumulation
Authors: Novotný Ladislav , Smoler Ivan
Published: September 2010

Using drop time technique with long drop times and a controlled convection of the solution the surface tension data of Hg with tetrapropylammonium perchlorate in 0.1 mol l-1 NaClO4 in the concentration range 4 . 10-6 - 3 . 10-3 mol l-1 have been obtained. The corresponding adsorption parameters have been evaluated from the Frumkin isotherm both at constant potential E and at constant charge q. Both E and q could be chosen as an independent electrical variable. The maximum free adsorption energy amounts to approx. -36.5 kJ mol-1. The congruence of adsorption isotherms with respect to E and with respect to q was very well fulfilled for the surface coverage Θ ⪬ 0.6-0.7.
The structure of 2-oxo-8α-angeloyloxy-11α-acetoxy-5βH,6αH,7αH-guai-1(10),3-dien-6,12-olide, a sesquiterpenic lactone from Laserpitium prutenicum L. revision of the stereostructures of native 2-oxoguai-1(10),3-dien-6,12-olides from the species of the Umbelliferae family
Authors: Rychłewska Urszula , Hodgson Derek J. , Holub Miroslav , Buděšínský Miloš , Smítalová Zdenka
Published: September 2010

On the basis of an analysis of its NMR spectra and X-ray analysis the stereostructure of the so-called 4-acetoxypruteninone-(10) (laferin) has been corrected to that of formula I. The stereostructures of almost all so far described native 2-oxoguai-1(10),3-dien-6,12-olides isolated from the species of Umbelliferae have been corrected on the basis of 1H NMR parameters.
IR spectra of deuterated propene analogues of Zeise's salt
Authors: Řeřicha Roman , Zdražil Miroslav
Published: September 2010

The IR absorption spectra (4 000-250 cm-1) of anhydrous K[(propene)PtCl3], using propene-2-d1 and propene-1,1-d2 as the ligands, were measured in KBr discs. A new weak band for the fundamental deformation frequency of the C-C=C skeleton softened by the coordination of the propenes was found around 400 cm-1, namely at 420, 417, and 375 cm-1 for d0, d1, and d2 species, resp. Vibrational couplings of the so-called ν(C=C) with other modes of the ligands is discussed.
Theoretical and experimental investigation of the function of the wall flow deflecting ring. A single ring
Authors: Staněk Vladimír , Semkov Krumm , Kolev Nikolai , Paskalev Georgii
Published: September 2010

Theoretical model has been formulated of the flow of liquid in a randomly packed trickle bed column equipped with special wall flow deflecting rings (WFDR). Solutions have been obtained of the model for the case of a single ring. Theoretical results have been compared with experimental distributions of liquid in a 188.6 mm in diameter column packed with 25 mm Raschig rings and equipped with a single WFDR. Reasonable agreement of the theory with experimental results has been found and the theory is felt to be important in the future for optimizations of the number, size and spacing of the WFDR's to be used in industrial columns to check the extent of the flow on the wall.
Influence of free convection on the diffusion current to a sphere in a laminar forced flow regime
Authors: Kimla Arnošt , Míčka Jiří
Published: September 2010

The formulation and solution of a boundary value problem is presented, describing the influence of the free convective diffusion on the forced one to a sphere for a wide range of Rayleigh, Ra, and Peclet, Pe, numbers. It is assumed that both the free and forced convection are oriented in the same sense. Numerical results obtained by the method of finite differences were approximated by an empirical formula based on an analytically derived asymptotic expansion for Pe → ∞. The concentration gradient at the surface and the total diffusion current calculated from the empirical formula agree with those obtained from the numerical solution within the limits of the estimated errors.
Reactivity of 2,2-difluoro-3-methyl-3-butenal toward some O-, N- and C-nucleophiles
Authors: Veselý Ivan , Dědek Václav
Published: September 2010

Addition of nucleophiles to 2,2-difluoro-3-methyl-3-butenal (I) is complicated by its spontaneous polymerization. Compound I afforded neither hydrate nor dimethyl acetal but reacted with ethylene glycol to give the cyclic acetal II. Reaction with acetyl chloride and acetic anhydride led to the respective acetate III and diacetate IV. Satisfactory reaction with N-nucleophiles was observed only in the case of hydroxylamine and dinitrophenylhydrazine. Diethylamine reacted with I only at 150 °C to give the reduction product VI and the ethylaldimine VII. The compound I added nitromethane and sodium cyanide (giving X and XI, respectively); the adducts or products of their reduction with lithium aluminium hydride were hydroxylated at the double bond to give analogues of alcoholic sugars with difluoromethylene group in position 3. Hydroxylation of the butenal I or the acetate III afforded 3,3-difluoro-2,4-dihydroxy-4-methyloxolane (XIX) which was prepared also by cleavage of the acetal XVIII obtained from II by hydroxylation. Addition of bromine to the double bond in III and IV gave the dibromo derivatives XV and XVI; the attempted replacement of bromine in XV and XVI by acetate anion failed. Bromination of I in aqueous medium afforded 3-bromo-2,2-difluoro-3-methyl-4-butanolide (XIV).
Time dependent interfacial behaviour of tributylphosphine oxide at the mercury-solution interface
Authors: Anastopoulos Anastos , Nikitas Panaghiotis , Jannakoudakis Demetrios
Published: September 2010

A series of methods are used for the quantitative description of the time dependent interfacial behaviour of tributylphosphine oxide (TBPO). These methods include measurements of the interfacial tension by a capillary electrometer as well as differential capacitance measurements with a dropping mercury electrode (D.M.E.) of short drop times (⪬5 s), a D.M.E. of large drop times (~20 s) and a hanging mercury drop electrode (H.M.D.E.). The capacitance measurements with large drop times reveal the existence of peculiarities during the development of the adsorption film. The adsorption equilibrium of TBPO, at the vicinity of the adsorption maximum, is generally established within times shorter than 10 s. At the region of the adsorption pseudocapacity, time intervals ranging from 200 to 400 seconds are required for the equilibrium. The adsorption parameters derived with the large drop time D.M.E., are in reasonable agreement with those obtained by electrocapillary measurements.
Influence of protons on electrochemical behaviour of the system quinone-hydroquinone in dichloromethane
Authors: Hanzlík Josef , Samec Zdeněk
Published: September 2010

Additions of strong acids to a solution of quinone in dichloromethane lead to protolytic equilibria which have a marked influence on its electrochemical behaviour. In the presence of free protons, the electroactive species is the monoprotonated form of quinone, QH+, and at higher acid concentrations the species QH22+ is formed with the acidity constant pK(QH+/QH22+) = 1.2. The overall equilibrium EC reaction scheme necessarily involves also the protonated forms of hydroquinone, at least the species QH3+ which is, in contrast to the inactive hydroquinone, electroactive on the dropping mercury electrode in the medium of dichloromethane.
Dynamic sorption of Cr3+ on strongly acidic cation exchangers and separation of Cr(VI), Cr3+ and cations interfering with the spectrophotometric determination of chromium
Authors: Pancl Jan
Published: September 2010

The dynamic sorption of Cr3+ on two strongly acidic cation exchangers, viz. the microreticular Ionenaustauscher I and the macroreticular Amberlyst 15, is studied by measuring the breakthrough curves for the hexaquochromium(III) ions, products of their partial hydrolysis, and mixtures of Cr3+ with Co2+, Cr2+, and Ni2+ ions, hence, ions interfering with the spectrophotometric determination of chromium. Analysis of the breakthrough curves made it possible to find the experimental conditions for the quantitative separation of Cr(VI) from Cr3+ and for the separation of chromium from the interfering cations. A procedure for the determination of Cr(VI), Cr3+ and total chromium in the presence of the interfering ions is based on the oxidation of Cr3+ with hydrogen peroxide, reduction of Cr(VI) with hydroxylammonium chloride, separation of Cr(VI) on a strongly acidic cation exchanger, and spectrophotometric determination of Cr3+ with DCTA.
Iridoid glucosides from Penstemon diffusus
Authors: Diak Joanna , Kohlmünzer Stanisłav
Published: September 2010

From the aerial parts of Penstemon diffusus DOUGL. (Scrophulariaceae) have been isolated three iridoid glucosides: penstemide (I), aucubin (V), and loganin (VIII). The identity of the compounds and their derivatives has been confirmed by spectroscopic data.
Preparation of isomeric 2-methyl-3-oxolupane-28-nitriles
Authors: Klinot Jiří , Světlý Jarmil , Klinotová Eva , Vystrčil Alois
Published: September 2010

2β-Methyl- and 2α-methyl-3-oxo derivatives of lupane-28-nitrile XV and XVI were prapared from betulin-3-acetate (I). The key steps of the synthesis were the condensation of ketone VII with formaldehyde and dimethylamine hydrochloride, conversion of the methylene ketone VIII formed to 3β-acetoxy-2-methylene derivative X and hydrogenation of the exomethylene double bond. Both 2-methyl-3-oxo derivatives, XV and XVI, are approximately equally stable; in their equilibrium mixture 47 ± 3% of the 2β-isomer were found.
Ethical issues related to computerised family medical histories in sickle cell disease: Inforare
Authors: Franrenet Sandra , Duchange Nathalie , Galactéros Fréderic , Quantin Catherine , Cohen Olivier , Nzouakou Ruben , Sudraud Sophie , Hervé Christian , Moutel Grégoire
Published: September 2010

The Inforare project aims to set up a system for the sharing of clinical and familial data, in order to study how genes are related to the severity of sickle cell disease. While the computerisation of clinical records represents a valuable research goal, an ethical framework is necessary to guarantee patients' protection and their rights in this developing field. Issues relating to patient information during the Inforare study were analysed by the steering committee. Several major concerns were discussed by the committee and formalised in the patients' information letter: educating patients to aid the recruitment of family members, rules of confidentiality and the disclosure of aggregate, individual and unexpected research results. This paper presents the main issues addressed.
STABLE CHROMOMAGNETIC QCD VACUUM AND CONFINEMENT
Authors: PARTHASARATHY R.
Published: September 2010

The stable chromomagnetic vacuum for SU(2) Yang–Mills theory found earlier is shown to give a model for confinement in QCD, using Wilson loop and a linear potential (in the leading order) for quark–antiquark interaction. The coefficient k in this potential is found to be ~ 0.25 GeV2, in satisfactory agreement with nonrelativistic potential model calculations for charmonium. At finite temperature, the real effective energy density found earlier is used to obtain estimates of the deconfining temperature agreeing reasonably with lattice study for SU(2).
ASYMPTOTIC AdS STRING SOLUTIONS FOR NULL POLYGONAL WILSON LOOPS IN R1,2
Authors: RYANG SHIJONG
Published: September 2010

For the asymptotic string solution in AdS3 which is represented by the AdS3 Poincaré coordinates and yields the planar multi-gluon scattering amplitude at strong coupling in arXiv:0904.0663, we express it by the AdS4 Poincaré coordinates and demonstrate that the hexagonal and octagonal Wilson loops surrounding the string surfaces take closed contours consisting of null vectors in R1,2 owing to the relations of Stokes matrices. For the tetragonal Wilson loop we construct a string solution characterized by two parameters by solving the auxiliary linear problems and demanding a reality condition, and analyze the asymptotic behavior of the solution in R1,2. The freedoms of two parameters are related with some conformal SO(2,4) transformations.
ENTROPY QUANTIZATION OF D-DIMENSIONAL GAUSS–BONNET BLACK HOLES
Authors: REN JI-RONG , JIA LIN-YU , MAO PU-JIAN
Published: September 2010

The entropy and area spectra for D-dimensional Gauss–Bonnet black holes are investigated from two different approaches, which are the quasinormal modes approach developed by Hod, Kunstatter and Maggiore, and the very recent method proposed by Ropotenko. The two methods give the same results, which show that the entropy spectrum of Gauss–Bonnet black holes is equidistantly quantized with spacing ΔS = 2πℏ, while the area spectrum is not equally spaced.
ON FLAVOR CONSERVATION IN WEAK INTERACTION DECAYS INVOLVING MIXED NEUTRINOS
Authors: BLASONE MASSIMO , CAPOLUPO ANTONIO , JI CHUENG-RYONG , VITIELLO GIUSEPPE
Published: September 2010

In the context of quantum field theory (QFT), we compute the amplitudes of weak interaction processes such as W+ →e+ + νe and W+ →e+ + νμ by using different representations of flavor states for mixed neutrinos. Analyzing the short time limit of the above amplitudes, we find that the neutrino states defined in QFT as eigenstates of the flavor charges lead to results consistent with lepton charge conservation. On the contrary, the Pontecorvo flavor states produce a violation of lepton charge in the vertex, which is in contrast with what expected at tree level in the Standard Model.
SEEBECK EFFECT OF NANO-SCALE P-TYPE SILICON FILMS ABOVE ROOM TEMPERATURE
Authors: HOU Q. R. , GU B. F. , CHEN Y. B.
Published: September 2010

Nano-scale Al -doped silicon films are prepared by magnetron sputtering. The amount of Al doped in the films is controlled by regulating the Al sputtering power and duration. With appropriate amount of Al , the Seebeck coefficient of the Si films at room temperature is larger than 168 μV/K, which increases with temperature in agreement with the conventional theory for three-dimensional semiconductors. By reducing the Al sputtering time, however, step-like Seebeck coefficient versus temperature is observed. This anomalous behavior is explained by the step-like density of states for two-dimensional semiconductors.
EVALUATING OPTICAL PARAMETERS FROM ELECTRONIC STRUCTURE AND CRYSTAL STRUCTURE FOR BINARY (ANB8-N) AND TERNARY $({\rm A}^N {\rm B}^{2 + N}{\rm C}^{7 - N}_2)$ TETRAHEDRAL SEMICONDUCTORS
Authors: VERMA AJAY SINGH , SHARMA SHEETAL , JINDAL V. K.
Published: September 2010

In this paper, we present new empirical relations to evaluate opto-electronic properties such as refractive index (n), band gap (Eg) and optical electronegativity (Δχ) in terms of electronic structure of atoms (i.e. valence electrons) and crystal structure of materials (i.e. nearest-neighbor distance, d) for zinc blende ( A II B VI and A III B V ) and chalcopyrites ([Formula: see text] and [Formula: see text]) structured solids. The refractive index (n), band gap (Eg) and optical electronegativity (Δχ) of these solids exhibit a linear relationship when plotted against the nearest-neighbor distance d (Å), but fall on different straight lines according to the product of the valence electron of the compounds. We have applied the proposed relation on these solids and found a better agreement with the experimental data as compared to the values evaluated by earlier researchers.
NONLINEAR STABILITY OF LARGE AMPLITUDE VISCOUS SHOCK WAVES OF A GENERALIZED HYPERBOLIC–PARABOLIC SYSTEM ARISING IN CHEMOTAXIS
Authors: LI TONG , WANG ZHI-AN
Published: September 2010

Traveling wave (band) behavior driven by chemotaxis was observed experimentally by Adler1,2 and was modeled by Keller and Segel.15 For a quasilinear hyperbolic–parabolic system that arises as a non-diffusive limit of the Keller–Segel model with nonlinear kinetics, we establish the existence and nonlinear stability of traveling wave solutions with large amplitudes. The numerical simulations are performed to show the stability of the traveling waves under various perturbations.
Performance Management System at Gas Company
Authors: Siti-Nabiha A. K.
Published: September 2010

The case is about the implementation of a performance management system (PMS) in ALPHA, a gas processing company. ALPHA is also a subsidiary of a multinational company based in Malaysia. The new performance management system was imposed on ALPHA by its parent company.

The PMS integrates the following key management processes, i.e. strategic planning, portfolio management, resource allocation, performance measurement and reporting and executive compensation in the organization. The ultimate aim of the new system is to ensure that the focus of business activities is on economic value creation. At the heart of this system is the use of key performance indicators (KPIs) for each of the management processes coupled with performance targets for all the KPIs.

However, there were various implementation problems in the company. The employees had difficulty in formulating their performance indicators. There was also confusion and anxiety among the organizational members regarding the new system, specifically on how it would impact on their performance appraisal. Consequently, most of the employees formulated two sets of indicators, one to be used for their performance appraisal and another indicator for the performance management system, which is not used in their evaluation system.

Ms. Marinah, the General Manager of the Finance Division and also the person responsible for the implementation of the new performance management system needs to make a decision as to whether to continue the usage of two sets of indicators for the parent company or to brief the managers again about the usage of value based indicators for their appraisal system.
NON-GAUSSIAN NOISE- AND COUPLING-INDUCED FIRING TRANSITIONS OF NEWMAN-WATTS NEURONAL NETWORKS
Authors: GONG YUBING , LIN XIU , HAO YINGHANG , MA XIAOGUANG
Published: September 2010

In this Letter, we study firing transitions induced by a particular kind of non-Gaussian noise (NGN) and coupling in Newman-Watts small-world neuronal networks. It is found that chaotic bursting can be tamed by the coupling and evolves to regular spiking or bursting behavior as the coupling increases. As the NGN's deviation from Gaussian noise changes, the neurons exhibit firing transitions from irregular spiking to regular bursting, and the number of spikes inside per burst varies with the change of the deviation. These results show that the NGN and the coupling play crucial roles in the firing activity of the neurons, and hence are of great importance to the information processing and transmission in the neuronal networks.
A FULL NUMERICAL ANALYSIS OF ELASTOHYDRODYNAMIC LUBRICATION IN KNEE PROSTHESIS UNDER WALKING CONDITION
Authors: SU YONGLIN , FU ZENGLIANG , YANG PEIRAN , WANG CHENGTAO
Published: September 2010

Lubrication plays an important role in reducing prosthetic wear. Time-dependent elastohydrodynamic lubrication simulation for total knee replacements was carried out under physiological loading and motions of a gait cycle. In numerical implement, a simplified ellipsoid-on-plane configuration was introduced to represent the artificial knee joint. Load and motions came from ISO standard, and both anterior–posterior displacement and flexion–extension rotation were considered to realize sliding and rolling motions of the knee. The governing Reynolds and elasticity equations were solved simultaneously using the multigrid technique. The elastic deformation was calculated based on the constrained column model. The results show that: (i) under the combination of entraining and squeeze-film actions throughout the walking cycle, the predicted central film thickness decreases during stance phase and keeps a relatively larger value in swing phase; (ii) high joint conformity helps to reduce hydrodynamic pressure and increase lubrication film thickness; (iii) the thickness of ultra-high molecular weight polyethylene layer and its properties also have influence on the lubrication performance in artificial knee replacement. Based on the aforementioned EHL analysis, potential surface damage of knee implants can be further evaluated.
Palaeoecological and palaeoenvironmental influences revealed by long-bone palaeohistology: the example of the Permian branchiosaurid
Apateon
Authors: Sanchez Sophie , Steyer J. Sébastien , Schoch Rainer R. , De Ricqlès Armand
Published: September 2010

Apateon
, a small temnospondyl from the Permian freshwater-lake deposits of the Saar-Nahe Basin (SW Germany), is known by exceptionally well-preserved material. Here we report the first palaeohistological analysis of
Apateon
that focuses on its life-history traits and palaeoenvironments. Different samples (different localities and horizons) of
Apateon caducus
and
Apateon pedestris
have been analysed. Their stylopod histology shows different growth rhythms that might be correlated to changes in palaeoecosystems: food availability and/or presence of predators. Palaeoenvironmental influences are also recognized during the limb-bone osteogenesis by the expression of simple and/or double patterns of Lines of Arrested Growth (LAG). A double-LAG pattern expresses hibernating and aestivating arrests of growth in extant newts. The fossil samples from the two stratigraphically oldest horizons preserved a similar double-LAG pattern, suggesting that they may have hibernated and aestivated every year because of harsh climatic conditions. The Saar-Nahe lake system probably passed from a higher altitude zone into a lower one, possibly because of subsidence and/or erosion. It could also be correlated to the size of the lakes that differs from one locality to another, inducing different responses of the organisms to the climatic variations.
The effects of terrestrialization on marine ecosystems: the fall of CO
2
Authors: Strother Paul K. , Servais Thomas , Vecoli Marco
Published: September 2010

The rise of land plants during the early Palaeozoic had profound effects upon subsequent Earth history and evolution. The sequestration of standing biomass and carbon burial caused a primary shift in the distribution of active carbon within the biosphere and surficial Earth systems. This manifested itself in a dynamic decline in
p
CO
2
during Silurian–Devonian time, affecting both terrestrial and marine ecosystems. We examined first-order correlations between terrestrialization and
p
CO
2
by comparing the GEOCARB III data with time-constrained fossil events in the early evolution of land plants. We compared the same GEOCARB III data with the species/genus richness of lower Palaeozoic acritarchs. The correlation between the rise of woody plants and
p
CO
2
is built into the GEOCARB model for the Late Devonian and later, but
p
CO
2
begins to decline in the Cambrian long before the origin of woody trees (lignophytes). The influence of early phases in plant evolution may be seen in a two-stage
p
CO
2
decline corresponding to fossil evidence for the origin of thalloid bryophytes in the Middle Cambrian and the origin of tracheophytes near the Ordovician–Silurian boundary. The decline of the acritarchs shows a highly correlated lag of about 10 Ma with respect to the
p
CO
2
decline. The relation between
p
CO
2
and acritarch species richness suggests a tight coupling between the evolution of the marine phytoplankton and atmospheric CO
2
, supporting previous suggestions that
p
CO
2
was a significant causal factor in the near extinction of acritarchs by the end of the Devonian.
The land plant cover in the Devonian: a reassessment of the evolution of the tree habit
Authors: Meyer-Berthaud B. , Soria A. , Decombeix A.-L.
Published: September 2010

This paper reviews information on the Devonian trees that evolved in the euphyllophyte clade with special focus on the Middle Devonian Pseudosporochnales. The morphology of pseudosporochnalean trees shows analogies with that of extant tree ferns, including the possession of an adventitious root system of limited extent at the base of the trunk. Direct evidence on how these trees were constructed is scarce. We propose a growth model integrating information from younger representatives of the same class known to reach large diameters. According to this model, trunk width in its aerial part results from the large size of its primary body where living tissues are abundant, a condition reached early during growth. Secondary xylem contributes little to trunk diameter. This model sharply diverges from that of the Late Devonian archaeopteridalean trees characterized by an extended root system and where trunk diameter and mechanical support are achieved by the substantial development of secondary vascular tissues. These differences suggest that pseudosporochnalean trees may have had a lesser impact on Devonian environments than the Archaeopteridales. The important investment in living tissues in the Pseudosporochnales probably made them vulnerable to drought and cold.
Noise and Robustness in Prokaryotic Regulatory Networks
Authors: Silva-Rocha Rafael , de Lorenzo Víctor
Published: September 2010

Robustness is the quality of any relational object (biological or otherwise) to maintain its components, its structure, and its function despite both external changes and endogenous fluctuations. Live systems are surprisingly robust, as they are able to not only preserve their physi-cochemical architecture in the face of variable nutritional and environmental conditions, but also tolerate stochastic variability in the concentrations of their components, fix errors resulting from hazardous events, and make virtually perfect copies of themselves. These qualities have started to be comprehended in full only since the application of network theory formalisms to regulatory phenomena. This review addresses the distinct role of network architecture (topology, logic) and biochemical/kinetic parameters in the materialization of various archetypical robust gene expression circuits in prokaryotes. Some take-home lessons for the construction of artificial regulatory networks (one of the trademarks of synthetic biology) are to be derived from such state of affairs.
Organelle-Like Membrane Compartmentalization of Positive-Strand RNA Virus Replication Factories
Authors: den Boon Johan A. , Ahlquist Paul
Published: September 2010

Positive-strand RNA virus genome replication is invariably associated with extensively rearranged intracellular membranes. Recent biochemical and electron microscopy analyses, including three-dimensional electron microscope tomographic imaging, have fundamentally advanced our understanding of the ultrastructure and function of organelle-like RNA replication factories. Notably, for a range of positive-strand RNA viruses embodying many major differences, independent studies have revealed multiple common principles. These principles include that RNA replication often occurs inside numerous virus-induced vesicles invaginated or otherwise elaborated from a continuous, often endoplasmic reticulum-derived membrane network. Where analyzed, each such vesicle typically contains only one or a few genome replication intermediates in conjunction with many copies of viral nonstructural proteins. In addition, these genome replication compartments often are closely associated with sites of virion assembly and budding. Our understanding of these complexes is growing, providing substantial new insights into the organization, coordination, and potential control of crucial processes in virus replication.
Bacterial Sensor Kinases: Diversity in the Recognition of Environmental Signals
Authors: Krell Tino , Lacal Jesús , Busch Andreas , Silva-Jiménez Hortencia , Guazzaroni María-Eugenia , Ramos Juan Luis
Published: September 2010

Bacteria sense and respond to a wide range of physical and chemical signals. Central to sensing and responding to these signals are two-component systems, which have a sensor histidine kinase (SK) and a response regulator (RR) as basic components. Here we review the different molecular mechanisms by which these signals are integrated and modulate the phosphorylation state of SKs. Apart from the basic mechanism, which consists of signal recognition by the SK that leads to an alteration of its autokinase activity and subsequently a change in the RR phosphorylation state, a variety of alternative modes have evolved. The biochemical data available on SKs, particularly their molecular interactions with signals, nucleotides, and their cognate RRs, are also reviewed.
Basis of Virulence in Community-Associated Methicillin-ResistantStaphylococcus aureus
Authors: Otto Michael
Published: September 2010

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains are causing a severe pandemic of mainly skin and soft tissue and occasionally fatal infections. The basis of their success is the combination of methicillin resistance at low fitness cost and high virulence. Investigation of the virulence potential of CA-MRSA, a key prerequisite for the development of anti-CA-MRSA therapeutics, has focused on strain USA300, which is responsible for the most serious CA-MRSA epidemic seen in the United States. Current data indicate that in this strain virulence evolved via increased expression of core-genome-encoded virulence determinants, such as alpha-toxin and phenol-soluble modulins, and acquisition of the phage-encoded Panton-Valentine leukocidin (PVL) genes. All these toxins impact disease progression in animal models of USA300 infection. In contrast, the basis of virulence in other CA-MRSA epidemics, which also include PVL-negative strains, is poorly understood.
HMGB1 inhibits macrophage activity in efferocytosis through binding to the αvβ3-integrin
Authors: Friggeri Arnaud , Yang Yanping , Banerjee Sami , Park Yong-Jun , Liu Gang , Abraham Edward
Published: September 2010

Phagocytosis of apoptotic cells is critical to resolution of inflammation. High mobility group box 1 protein (HMGB1), a mediator of inflammation, has been shown to diminish phagocytosis through binding to phosphatidylserine (PS) exposed on the surface of apoptotic neutrophils. However, it is currently unknown whether HMGB1 also modulates the activity of receptors involved in PS recognition on the surface of phagocytes. In the present studies, we found that preincubation of macrophages with HMGB1 decreased their ability to engulf apoptotic neutrophils or thymocytes. Preincubation of macrophages with HMGB1 prevented the enhancement of efferocytosis resulting from exposure to milk fat globule EGF factor 8 (MFG-E8), an opsonin that bridges PS and αvβ3 as well as αvβ5-integrins on the surface of phagocytes. The inhibitory effect of HMGB1 on the phagocytic activity of macrophages was prevented by preincubation of HMGB1 with soluble αvβ3, but not with soluble αvβ5. HMGB1 colocalized with the β3-integrin on the cell membrane of macrophages and bound to soluble αvβ3, but not to soluble αvβ5. HMGB1 suppressed the interaction between MFG-E8 and αvβ3. HMGB1 also inhibited intracellular signaling events, including ERK phosphorylation and Rac-1 activation, which are activated in macrophages during phagocytosis of apoptotic cells. These results demonstrate that HMGB1 blocks αvβ3-dependent recognition and uptake of apoptotic cells.
Mechanical strain and TLR4 synergistically induce cell-specific inflammatory gene expression in intestinal smooth muscle cells and peritoneal macrophages
Authors: Wehner Sven , Buchholz Bettina M. , Schuchtrup Silke , Rocke Anatol , Schaefer Nico , Lysson Mariola , Hirner Andreas , Kalff Joerg C.
Published: September 2010

Mechanical trauma of the gut is an unavoidable event in abdominal surgery. Former studies demonstrated that intestinal manipulation induces a strong inflammation within the tunica muscularis. We hypothesized that mechanical strain initiates or aggravates proinflammatory responses in intestinal smooth muscle cells (iSMC) or macrophages. First, an appropriate isolation and culture method for neonatal rat iSMC was established. Purified iSMC and primary peritoneal macrophages (pMacs) were subjected to static or cyclic strain, and gene expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IL-6, and IL-1β was analyzed by quantitative PCR. Supernatants from stretched iSMC were transferred to untreated pMacs or contrariwise, and medium transfer-triggered inflammatory gene expression was measured in unstretched cells. Finally, we investigated the synergistic effect of static strain on LPS-induced proinflammatory gene expression. Although cyclic strain failed, static strain significantly induced iNOS, COX-2, and IL-1β mRNA in iSMC. pMacs showed an increase in all inflammatory genes investigated as well as macrophage inflammatory protein (MIP)-1α and MIP-2 mRNA after static strain. Both cell entities liberated unknown mediators in response to stretch that mutually stimulated iNOS gene expression. Finally, mechanostimulation amplified LPS-induced iNOS and IL-1β gene expression in iSMC as well as COX-2 and IL-6 mRNA in pMacs. In conclusion, static strain initiates proinflammatory gene expression in iSMC and pMacs and triggers a bidirectional paracrine communication between both cultured cell entities via the liberation of unknown mediators. Furthermore, static strain synergistically operates with Toll-like receptor 4 ligation in a cell-specific manner. Hence, this study demonstrates that mechanical strain functions as an immunomodulatory stimulus in abdominal cells.
Adaptive thermogenesis and thermal conductance in wild-type and UCP1-KO mice
Authors: Meyer Carola W. , Willershäuser Monja , Jastroch Martin , Rourke Bryan C. , Fromme Tobias , Oelkrug Rebecca , Heldmaier Gerhard , Klingenspor Martin
Published: September 2010

We compared maximal cold-induced heat production (HPmax) and cold limits between warm (WA; 27°C), moderate cold (MCA; 18°C), or cold acclimated (CA; 5°C) wild-type and uncoupling-protein 1 knockout (UCP1-KO) mice. In wild-type mice, HPmax was successively increased after MCA and CA, and the cold limit was lowered to −8.3°C and −18.0°C, respectively. UCP1-KO mice also increased HPmax in response to MCA and CA, although to a lesser extent. Direct comparison revealed a maximal cold-induced recruitment of heat production by +473 mW and +227 mW in wild-type and UCP1-KO mice, respectively. The increase in cold tolerance of UCP1-KO mice from −0.9°C in MCA to −10.1°C in CA could not be directly related to changes in HPmax, indicating that UCP1-KO mice used the dissipated heat more efficiently than wild-type mice. As judged from respiratory quotients, acutely cold-challenged UCP1-KO mice showed a delayed transition toward lipid oxidation, and 5-h cold exposure revealed diminished physical activity and less variability in the control of metabolic rate. We conclude that BAT is required for maximal adaptive thermogenesis but also allows metabolic flexibility and a rapid switch toward sustained lipid-fuelled thermogenesis as an acute response to cold. In both CA groups, expression of contractile proteins (myosin heavy-chain isoforms) showed minor training effects in skeletal muscles, while cardiac muscle of UCP1-KO mice had novel expression of beta cardiac isoform. Neither respiration nor basal proton conductance of skeletal muscle mitochondria were different between genotypes. In subcutaneous white adipose tissue of UCP1-KO mice, cold exposure increased cytochrome- c oxidase activity and expression of the cell death-inducing DFFA-like effector A by 3.6-fold and 15-fold, respectively, indicating the recruitment of mitochondria-rich brown adipocyte-like cells. Absence of functional BAT leads to remodeling of white adipose tissue, which may significantly contribute to adaptive thermogenesis during cold acclimation.
Ventilatory restraint of sympathetic activity during chemoreflex stress
Authors: Steinback Craig D. , Breskovic Toni , Frances Maria , Dujic Zeljko , Shoemaker J. Kevin
Published: September 2010

The within-breath modulation of muscle sympathetic nerve activity (MSNA) is well established, with greater activity occurring during expiration and less during inspiration. Whether ventilation per se affects the longer-term (i.e., minute-to-minute) regulation of MSNA has not been determined. We sought to define the specific role of ventilation in regulating sympathetic activation during chemoreflex activation, where both ventilation and MSNA are increased. Ten young healthy subjects performed both asphyxic rebreathing and repeated, rebreathing apneas to cause the same magnitude of chemoreflex stress in the presence or absence of ventilation. Both protocols caused increases in sympathetic burst frequency, burst amplitude, and burst incidence. However, burst frequency was increased more during repeated apneas (12 ± 6 to 25 ± 7 bursts/min) compared with rebreathing (12 ± 5 to 17 ± 7 bursts/min; P < 0.001) due to a greater burst incidence during apneas (36 ± 11 bursts/100 heart beats) vs. rebreathing (26 ± 8 bursts/100 heart beats, P < 0.001). The sympathetic gain to chemoreflex stress was also larger during repeated apneas (2.29 ± 1.29 au/% desaturation) compared with rebreathing (1.44 ± 0.53 au/% desaturation, P < 0.05). The augmented sympathetic response during apneas was associated with a larger pressor response and total peripheral resistance compared with rebreathing. These data demonstrate that ventilation per se restrains sympathetic activation during chemoreflex activation. Further, the augmented sympathetic response during apneas was associated with greater cardiovascular stress and may be relevant to the cardiovascular pathology associated with sleep-disordered breathing.
The pathogenesis of cystinosis: mechanisms beyond cystine accumulation
Authors: Wilmer Martijn J. , Emma Francesco , Levtchenko Elena N.
Published: September 2010

Renal proximal tubules are highly sensitive to ischemic and toxic insults and are affected in diverse genetic disorders, of which nephropathic cystinosis is the most common. The disease is caused by mutations in the CTNS gene, encoding the lysosomal cystine transporter cystinosin, and is characterized by accumulation of cystine in the lysosomes throughout the body. In the majority of the patients, this leads to generalized proximal tubular dysfunction (also called DeToni-Debré-Fanconi syndrome) in the first year and progressive renal failure during the first decade. Extrarenal organs are affected by cystinosis as well, with clinical symptoms manifesting mostly after 10 yr of age. The cystine-depleting agent cysteamine significantly improves life expectancy of patients with cystinosis, but offers no cure, pointing to the complexity of the disease mechanism. In this review, current knowledge on the pathogenesis of cystinosis is described and placed in perspective of future research.
Dynamic imaging of skeletal muscle contraction in three orthogonal directions
Authors: Lopata Richard G. P. , van Dijk Johannes P. , Pillen Sigrid , Nillesen Maartje M. , Maas Huub , Thijssen Johan M. , Stegeman Dick F. , de Korte Chris L.
Published: September 2010

In this study, a multidimensional strain estimation method using biplane ultrasound is presented to assess local relative deformation (i.e., local strain) in three orthogonal directions in skeletal muscles during induced and voluntary contractions. The method was tested in the musculus biceps brachii of five healthy subjects for three different types of muscle contraction: 1) excitation of the muscle with a single electrical pulse via the musculocutaneous nerve, resulting in a so-called “twitch” contraction; 2) a train of five pulses at 10 Hz and 20 Hz, respectively, to obtain a submaximum tetanic contraction; and 3) voluntary contractions at 30, 60, and 100% of maximum contraction force. Results show that biplane ultrasound strain imaging is feasible. The method yielded adequate performance using the radio frequency data in tracking the tissue motion and enabled the measurement of local deformation in both the vertical direction (orthogonal to the arm) and in the horizontal directions (parallel and perpendicular to direction of the arm) in two orthogonal cross sections of the muscle. The twitch experiments appeared to be reproducible in all three directions, and high strains in vertical (25 to 30%) and horizontal (−20% to −10%) directions were measured. Visual inspection of both the ultrasound data, as well as the strain data, revealed a relaxation that was significantly slower than the force decay. The pulse train experiments nicely illustrated the performance of our technique: 1) similar patterns of force and strain waveforms were found; and 2) each stimulation frequency yielded a different strain pattern, e.g., peak vertical strain was 40% during 10-Hz stimulation and 60% during 20-Hz stimulation. The voluntary contraction patterns were found to be both practically feasible and reproducible, which will enable muscles and more natural contraction patterns to be examined without the need of electrical stimulation.
Length oscillation mimicking periodic individual deep inspirations during tidal breathing attenuates force recovery and adaptation in airway smooth muscle
Authors: Raqeeb Abdul , Solomon Dennis , Paré Peter D. , Seow Chun Y.
Published: September 2010

Airway smooth muscle (ASM) is able to generate maximal force under static conditions, and this isometric force can be maintained over a large length range due to length adaptation. The increased force at short muscle length could lead to excessive narrowing of the airways. Prolonged exposure of ASM to submaximal stimuli also increases the muscle's ability to generate force in a process called force adaptation. To date, the effects of length and force adaptation have only been demonstrated under static conditions. In the mechanically dynamic environment of the lung, ASM is constantly subjected to periodic stretches by the parenchyma due to tidal breathing and deep inspiration. It is not known whether force recovery due to muscle adaptation to a static environment could occur in a dynamic environment. In this study the effect of length oscillation mimicking tidal breathing and deep inspiration was examined. Force recovery after a length change was attenuated in the presence of length oscillation, except at very short lengths. Force adaptation was abolished by length oscillation. We conclude that in a healthy lung (with intact airway-parenchymal tethering) where airways are not allowed to narrow excessively, large stretches (associated with deep inspiration) may prevent the ability of the muscle to generate maximal force that would occur under static conditions irrespective of changes in mean length; mechanical perturbation on ASM due to tidal breathing and deep inspiration, therefore, is the first line of defense against excessive bronchoconstriction that may result from static length and force adaptation.
Using near-infrared spectroscopy to measure cerebral metabolic rate of oxygen under multiple levels of arterial oxygenation in piglets
Authors: Tichauer Kenneth M. , Elliott Jonathan T. , Hadway Jennifer A. , Lee David S. , Lee Ting-Yim , St. Lawrence Keith
Published: September 2010

Improving neurological care of neonates has been impeded by the absence of suitable techniques for measuring cerebral hemodynamics and energy metabolism at the bedside. Currently, near-infrared spectroscopy (NIRS) appears to be the technology best suited to fill this gap, and techniques have been proposed to measure both cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2). We have developed a fast and reliable bolus-tracking method of determining CMRO2 that combines measurements of CBF and cerebral venous oxygenation [venous oxygen saturation (CSvO2)]. However, this method has never been validated at different levels of arterial oxygenation [arterial oxygen saturation (SaO2)], which can be highly variable in the clinical setting. In this study, NIRS measurements of CBF, CSvO2, and CMRO2 were obtained over a range of SaO2 in newborn piglets ( n = 12); CSvO2 values measured directly from sagittal sinus blood samples were collected for validation. Two alternative NIRS methods that measure CSvO2 by manipulating venous oxygenation (i.e., head tilt and partial venous occlusion methods) were also employed for comparison. Statistically significant correlations were found between each NIRS technique and sagittal sinus blood oxygenation ( P < 0.05). Correlation slopes were 1.03 ( r = 0.91), 0.73 ( r = 0.73), and 0.73 ( r = 0.81) for the bolus-tracking, head tilt, and partial venous occlusion methods, respectively. The bolus-tracking technique displayed the best correlation under hyperoxic (SaO2 = 99.9 ± 0.03%) and normoxic (SaO2 = 86.9 ± 6.6%) conditions and was comparable to the other techniques under hypoxic conditions (SaO2 = 40.7 ± 9.9%). The reduced precision of the bolus-tracking method under hypoxia was attributed to errors in CSvO2 measurement that were magnified at low SaO2 levels. In conclusion, the bolus-tracking technique of measuring CSvO2, and therefore CMRO2, is accurate and robust for an SaO2 > 50% but provides reduced accuracy under more severe hypoxic levels.
A Likelihood Method for Computing Selection Times in Spiking and Local Field Potential Activity
Authors: Banerjee Arpan , Dean Heather L. , Pesaran Bijan
Published: September 2010

The timing of neural responses to ongoing behavior is an important measure of the underlying neural processes. Neural processes are distributed across many different brain regions and measures of the timing of neural responses are routinely used to test relationships between different brain regions. Testing detailed models of functional neural circuitry underlying behavior depends on extracting information from single trials. Despite their importance, existing methods for analyzing the timing of information in neural signals on single trials remain limited in their scope and application. We develop a novel method for estimating the timing of information in neural activity that we use to measure selection times, when an observer can reliably use observations of neural activity to select between two descriptions of the activity. The method is designed to satisfy three criteria: selection times should be computed from single trials, they should be computed from both spiking and local field potential (LFP) activity, and they should allow us to make comparisons between different recordings. Our approach characterizes the timing of information in terms of an accumulated log-likelihood ratio (AccLLR), which distinguishes between two alternative hypotheses and uses the AccLLR to estimate the selection time. We develop the AccLLR procedure for binary discrimination using example recordings of spiking and LFP activity in the posterior parietal cortex of a monkey performing a memory-guided saccade task. We propose that the AccLLR method is a general and practical framework for the analysis of signal timing in the nervous system.