bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymorphisms of drug‐metabolizing enzymes and risk of childhood acute lymphoblastic leukemia
Authors: Pakakasama S. , Mukda E. , Sasanakul W. , Kadegasem P. , Udomsubpayakul U. , Thithapandha A. , Hongeng S.
Published: June 2005

The involvement of phase I and II enzymes is well documented in the metabolism of a wide range of drugs and xenobiotics. Single‐nucleotide polymorphisms (SNPs) of these enzymes are also known to alter their protein expression and function. Moreover, genetic susceptibility and environmental exposure have been proposed to be an etiology of cancer. We hypothesized that polymorphisms of these enzymes might affect the risk of childhood acute lymphoblastic leukemia (ALL). CYP 1A1, CYP 3A4*1B, CYP 3A5*3, CYP 3A5*6, GSTM1, and GSTT1 polymorphisms were genotyped by using PCR‐RFLP in 107 children with ALL and 320 healthy controls. Allele and genotype frequencies of each of the SNPs were compared between two groups. It was found that the allele frequencies of CYP 1A1*1, *2A, *2B, and *4 were not different between cases and controls. CYP 3A4*1B allele frequency was only 0.8% and 0.9% in ALL and controls, respectively. CYP 3A5*1/*1, *1/*3, and *3/*3 genotype frequencies showed no statistically significant difference between patients and controls. CYP 3A5*6 was not detected in our population. The GSTM1 null genotype was significantly increased in children with ALL (OR 1.7; 95% CI, 1.0, 2.7). In contrast, the GSTT1 null genotype did not show this effect. Our data thus demonstrate that the GSTM1 null genotype might increase the risk of childhood ALL in a Thai population. Am. J. Hematol. 79:202–205, 2005. © 2005 Wiley‐Liss, Inc.
Ultraviolet‐radiation‐induced graft copolymerization of methyl acrylate onto the sodium salt of partially carboxymethylated guar gum
Authors: Thaker M. D. , Trivedi H. C.
Published: June 2005

In an attempt to modify the sodium salt of partially carboxymethylated guar gum (Na‐PCMGG; degree of substitution = 0.291), we studied the ultraviolet‐radiation‐induced graft copolymerization of methyl acrylate with ceric ammonium nitrate as a photoinitiator. The influence of the grafting yield was studied as a function of the different reaction parameters, and the optimum reaction conditions for photografting were determined. The various reaction parameters included the photoinitiator, nitric acid, and monomer (methyl acrylate) concentrations, the reaction time, the temperature, and the amount of the substrate. A kinetic scheme for photografting copolymerization was proposed, and the results were in good agreement with the kinetic scheme. The graft copolymerization of methyl acrylate onto Na‐PCMGG (degree of substitution = 0291) in the presence and absence of ultraviolet radiation was also carried out for the study of the efficiency of the photoinitiator. The influence of carboxymethyl groups added to the guar gum molecule on its behavior toward ultraviolet‐radiation‐induced grafting with methyl acrylate was also investigated. The evidence of photografting was ascertained with IR spectroscopy and scanning electron microscopy techniques. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1977–1986, 2005
Synthesis and properties of poly(ether nitrile sulfone) copolymers with pendant methyl groups
Authors: Saxena Akanksha , Sadhana R. , Rao V. Lakshmana , Ravindran P. V. , Ninan K. N.
Published: June 2005

Poly(ether nitrile) and poly(ether nitrile sulfone) copolymers with pendant methyl groups were prepared by the nucleophilic substitution reaction of 2,6′‐dichlorobenzonitrile with methyl hydroquinone and with varying mole proportions of methyl hydroquinone and 4,4′‐dihydroxydiphenylsulfone using N‐methyl pyrrolidone as a solvent in the presence of anhydrous K2CO3. The polymers were characterized by different physicochemical techniques. Copolymer composition was determined using the FTIR technique. Thermogravimetric data revealed that all polymers were stable up to 420°C with a char yield above 40% at 900°C in a nitrogen atmosphere. The glass‐transition temperature increased and the activation energy and inherent viscosities decreased with an increase in the concentration of the 4,4′‐dihydroxydiphenylsulfone units in the polymer. Trimerization reactions were favorable with an increase in the concentration of methyl hydroquinone units in the polymer. The crystallinity of the polymer was also studied using wide‐angle X‐ray diffraction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1987–1994, 2005
Time–temperature superposition principle applied to a kenaf‐fiber/high‐density polyethylene composite
Authors: Tajvidi Mehdi , Falk Robert H. , Hermanson John C.
Published: June 2005

The time–temperature superposition principle was applied to the viscoelastic properties of a kenaf‐fiber/high‐density polyethylene (HDPE) composite, and its validity was tested. With a composite of 50% kenaf fibers, 48% HDPE, and 2% compatibilizer, frequency scans from a dynamic mechanical analyzer were performed in the range of 0.1–10 Hz at five different temperatures. Twelve‐minute creep tests were also performed at the same temperatures. Creep data were modeled with a simple two‐parameter power‐law model. Frequency isotherms were shifted horizontally and vertically along the frequency axis, and master curves were constructed. The resulting master curves were compared with an extrapolated creep model and a 24‐h creep test. The results indicated that the composite material was thermorheologically complex, and a single horizontal shift was not adequate to predict the long‐term performance of the material. This information will be useful for the eventual development of an engineering methodology for creep necessary for the design of structural building products from these composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1995–2004, 2005
Microemulsion polymerization kinetics and mechanisms
Authors: Chern Chorng‐Shyan , Tang Hsiu‐Jung
Published: June 2005

The mechanisms of microemulsion polymerizations stabilized by sodium dodecyl sulfate in combination with pentanol were investigated with a water‐insoluble dye as the probe. The major parameters chosen for study were the types of initiators [water‐soluble sodium persulfate (SPS) vs oil‐soluble 2,2′‐azobisisobutyronitrile (AIBN)] and the polarity of the monomers [relatively hydrophobic styrene (ST) vs relatively hydrophilic methyl methacrylate (MMA)]. Both continuous particle nucleation and limited particle flocculation had a significant influence on the polymerization kinetics. For the polymerizations investigated in this work, the relatively low initiation efficiency of AIBN resulted in a reaction system showing a quite different particle nucleation mechanism than that of the ST polymerization with SPS. The formation of particle nuclei in water was suppressed to some extent, and microemulsion droplet nucleation predominated in the ST polymerization initiated by AIBN. Homogeneous nucleation played an important role, and a mixed mode of particle nucleation (microemulsion droplet nucleation and homogeneous nucleation) was operative in the MMA polymerization. The MMA polymerization experienced stronger particle flocculation than its ST counterpart. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2005–2013, 2005
Mechanical properties of biodegradable composites from poly lactic acid (PLA) and microcrystalline cellulose (MCC)
Authors: Mathew Aji P. , Oksman Kristiina , Sain Mohini
Published: June 2005

Biodegradable composites were prepared using microcrystalline cellulose (MCC) as the reinforcement and polylactic acid (PLA) as a matrix. PLA is polyester of lactic acid and MCC is cellulose derived from high quality wood pulp by acid hydrolysis to remove the amorphous regions. The composites were prepared with different MCC contents, up to 25 wt %, and wood flour (WF) and wood pulp (WP) were used as reference materials. Generally, the MCC/PLA composites showed lower mechanical properties compared to the reference materials. The dynamic mechanical thermal analysis (DMTA) showed that the storage modulus was increased with the addition of MCC. The X‐ray diffraction (XRD) studies on the materials showed that the composites were less crystalline than the pure components. However, the scanning electron microscopy (SEM) study of materials showed that the MCC was remaining as aggregates of crystalline cellulose fibrils, which explains the poor mechanical properties. Furthermore, the fracture surfaces of MCC composites were indicative of poor adhesion between MCC and the PLA matrix. Biodegradation studies in compost soil at 58°C showed that WF composites have better biodegradability compared to WP and MCC composites. The composite performances are expected to improve by separation of the cellulose aggregates to microfibrils and with improved adhesion. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2014–2025, 2005
Synthesis of antibacterial polypropylene film with surface immobilized polyvinylpyrrolidone‐iodine complex
Authors: Xing Chang‐Min , Deng Jian‐Ping , Yang Wan‐Tai
Published: June 2005

A novel antibacterial material with surface immobilized polyvinylpyrrolidone‐iodine complex was synthesized facilely by a two‐step approach. First, N‐vinylpyrrolidone (NVP) was photografted onto polymeric substrates, and subsequently the surface‐grafted polyvinylpyrrolidone (PVP) underwent complexation of iodine. In the UV‐induced photografting process, PVP was efficiently grafted onto the polypropylene (PP) film surface by a unique film interlayer photopolymerization (FIP) technique; the grafting yield (Yg) could be controlled by varying the irradiation time or the monomer concentration. Further, we demonstrated that the grafted PVP chains could readily perform the complexation reaction with iodine as the homopolymer PVP does, which was characterized by UV–vis spectroscopy. The antibacterial activity of the modified polymer against Escherichia coli, Staphylococcus aureus, and Candida albicans was investigated. The results show that the modified PP film with surface‐immobilized PVP‐I complex has a desirable antibacterial property, with broad spectrum and high efficiency. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2026–2031, 2005
Plastic behavior of glassy polymers: Experimental and theoretical description based on three different approximations
Authors: Pandermarakis Z. G. , Spathis G.
Published: June 2005

Three different models were used for the description of viscoelastic, yielding, and hardening stages of the mechanical behavior of a network polymer. As a representative response we get unidirectional loading test at a wide range of strain rates with the appearance of a distinct yielding point, strain softening, and strain hardening. The present analysis shows that Rubin's kinematics formulation appears to have some benefits in contrast to the other two approximations. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2032–2046, 2005
Thermal decomposition of fluoropolymers and firing characteristics of priming compositions with fluoropolymers
Authors: Lee Jinn‐Shing
Published: June 2005

Many pyrotechnics contain binders, such as nitrocellulose, Viton, and other plastics and elastomers. Most pyrotechnics are prepared by the dispersion of fuel/oxidizer ingredients in a liquid solution, which are then mixed well to form pyrotechnics. The thermal decomposition behavior of a binder is very important to pyrotechnics in a polymer. In this work, the thermal decomposition behaviors of three fluoropolymers have been investigated with differential thermal analysis/thermogravimetry and differential scanning calorimetry. The parameters concerning decomposition have been evaluated with a nonisothermal technique, and a suitable binder is suggested for the Zr/KClO4 priming mixture. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2054–2059, 2005
Experimental and computational investigation of EVOH/clay nanocomposites
Authors: Aleperstein D. , Artzi N. , Siegmann A. , Narkis M.
Published: June 2005

Ethylene–vinyl alcohol copolymer (EVOH)/organoclay nanocomposites were prepared via a dynamic melt‐intercalation process. The effect of compatibilizers on the melt blending torque, intercalation level, and morphology of EVOH/organoclay systems was investigated. Maleic anhydride grafted ethylene vinyl acetate (EVA‐g‐ MA), or maleic anhydride grafted linear low‐density polyethylene (LLDPE‐g‐MA), were used to compatibilize EVOH with clay, at various concentrations (1, 5, and 10 wt %). Computer‐simulation techniques are used to predict structural properties and interactions of EVOH with compatibilizers in the presence and absence of clay. The simulation results strongly support the experimental findings and their interpretation. X‐ray diffraction shows enhanced intercalation within the galleries when the compatibilizers were added. Interestingly, results were obtained for the EVOH/clay/compatibilizer systems, owing to a high level of interaction developed in these systems. Thermal analysis shows that, upon increasing the compatibilizer content, lower crystallinity levels result, until at a certain compatibilizer content no crystallization is taking place. Significantly higher mixing viscosity levels were obtained for the EVOH/organoclay blends compared with the neat EVOH polymer. The storage modulus was higher compared with the uncompatibilized EVOH/organoclay blend in the presence of EVA‐g‐MA compatibilizer (at all concentrations), and only at low contents of LLDPE‐g‐MA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2060–2066, 2005
Synthesis and coordination of oxyquinolyl end‐functionalized polystyrene by atom transfer radical polymerization
Authors: Guo Xiang , Lu Jianmei , Li Hua , Yao Shechun , Wang Lihua
Published: June 2005

The end‐functionalized polystyrene is synthesized by a new initiator, 5‐chloromethyl‐8‐hydroxyquinoline (5‐ClCH2Q), via atom transfer radical polymerization. The existence of the oxyquinoline group on the chain end was confirmed by 1H‐NMR. The polymers can be easily changed into films with good fluorescence property and nonlinear third‐order optical property. Coordinating the oxyquinoline group with Eu3+ and La3+, the fluorescent intensity and third‐order nonlinear optical coefficient will be enhanced much more. The proportion of the oxyquinoline group coordinating and rare‐earth metal is 3:2 determined by titrimetric analysis. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2067–2071, 2005
The synthesis of copolymer–Cu coordinates and its catalysis to methyl methacrylate
Authors: Lu Jianmei , Wu Jianfei , Wang Lihua , Yao Shechun
Published: June 2005

The copolymerization of methacrylic acid, 2‐(dimethylamino) ethyl ester (DM), and allythiourea (AT) was studied under microwave, and the copolymer–copper coordinates Cu‐P(DM‐Co‐AT) was synthesized by the coordination between Cu2+ and the copolymer. IR, X‐ray photoelectron spectroscopy, and electronic spin resonance were used to analyze the structure of Cu‐P(DM‐Co‐AT). The results showed that the inherent viscosity of the copolymer obtained by microwave irradiation can be the maximum of 37.75 ml/g, and the productive rate can be 92%. The obtained Cu‐P(DM‐Co‐AT) can heterogeneously catalyze the polymerization of methyl methacrylate at room temperature. The maximal molecular weight of poly(methyl methacrylate) was 1,400,000. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2072–2075, 2005
Electrocopolymerization kinetics of a binary mixture of 3‐chloroaniline 2‐amino‐4‐phenylthiazole and characterization of the obtained block copolymer films
Authors: Sayyah S. M. , Abd EL‐Rehim S. S. , EL‐Deeb M. M
Published: June 2005

Electrocopolymerization of a binary mixture of 3‐chloroaniline and 2‐amino‐4‐phenylthiazole on platinum electrode in acid medium was carried out under different reaction conditions such as temperature, current density, hydrochloric acid, and monomer concentrations with duration time. The initial rate of the electrocopolymerization reaction on platinum electrode is small and the rate law is Rp = K2 [D]1.29[HCl]0.97[M]1.94. The apparent activation energy is found to be 38.87 kJ/mol. The obtained copolymer film is characterized by 1H‐NMR, elemental analysis, GPC IR, UV‐visible, and cyclic voltammetry and compared with those of the two homopolymers. The mechanism of the electrocopolymerization reaction is also discussed and the monomer reactivity ratio (r1and r2) is calculated. The thermogravimetric analysis (TGA) is used to confirm the proposed structure and determination of the number of water molecules in the polymeric chain unit. X‐ray and scanning electron microscopic analysis are used to investigate the surface morphology. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2076–2087, 2005
Brain morphology in nonsyndromic unicoronal craniosynostosis
Authors: Aldridge Kristina , Kane Alex A. , Marsh Jeffrey L. , Panchal Jayesh , Boyadjiev Simeon A. , Yan Peng , Govier Daniel , Ahmad Warda , Richtsmeier Joan T.
Published: June 2005

Studies of isolated craniosynostosis have shown biomechanical and biochemical influences on the craniofacial phenotype, resulting from both genetic and epigenetic factors. Much less attention has been directed toward the morphology of the brain, despite the interactive nature of the developing skull and developing brain. The aim of this study is to define the morphology of the brain in nonsyndromic unilateral coronal synostosis (UCS) in order to form more complete hypotheses about the cause of craniosynostosis. Landmark coordinate data were collected from 3D magnetic resonance image reconstructions of the brain in a sample of UCS patients and an age‐matched morphologically normal cohort. These data were analyzed using Euclidean distance matrix analysis. The results of our study demonstrate that despite the basic similarity of overall shape of the brain and skull in UCS, the effects of craniosynostosis on the brain are not localized to structures immediately adjacent to the fused suture or to the endocranial surface of the skull. Rather, alterations are observed throughout the volume of the brain, with subcortical structures altered in conjunction with cortical changes. These results indicate that the morphological correlates are different for brain and skull and suggest that there is a large degree of independence in the developmental trajectories of the brain and skull. © 2005 Wiley‐Liss, Inc.
Homeoidally striated density profiles: sequences of virial equilibrium configurations with constant anisotropy parameters
Authors: Caimmi R. , Marmo C.
Published: June 2005

The formulation of the tensor virial equations is generalized to unrelaxed configurations, where virial equilibrium does not coincide with dynamical (or hydrostatic) equilibrium. Homeoidally striated, Jacobi ellipsoids, which generalize classical Jacobi ellipsoids, are studied in detail. Further investigation is devoted to the generation of sequences of virial equilibrium configurations where the anisotropy parameters are left unchanged, including both flattened and elongated, triaxial configurations, and the determination of the related bifurcation points. An application is made to dark matter haloes hosting giant galaxies (M ≈ 1012 m⊙), with regard to assigned initial and final configuration, following and generalizing to many respects a procedure conceived by Thuan & Gott (1975). The dependence of the limiting axis ratios, below which no configuration is allowed for the sequence under consideration, on the change in mass, total energy, and angular momentum, during the evolution, is illustrated in some representative situations. The dependence of the axis ratios, ε31 and ε21, on a parameter, related to the initial conditions of the density perturbation, is analysed in connection with a few special cases. The same is done for the rotation parameters. Within the range of the rotation parameter, λ, deduced from high‐resolution numerical simulations, the shape of dark matter haloes is mainly decided by the amount of anisotropy in residual velocity distribution. On the other hand, the contribution of rotation has only a minor effect on the meridional plane, and no effect on the equatorial plane, as bifurcation points occur for larger values of λ. To this respect, dark matter haloes are found to resemble giant elliptical galaxies. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strong mean field dynamos require supercritical helicity fluxes
Authors: Brandenburg A. , Subramanian K.
Published: June 2005

Several one and two dimensional mean field models are analyzed where the effects of current helicity fluxes and boundaries are included within the framework of the dynamical quenching model. In contrast to the case with periodic boundary conditions, the final saturation energy of the mean field decreases inversely proportional to the magnetic Reynolds number. If a nondimensional scaling factor in the current helicity flux exceeds a certain critical value, the dynamo can operate even without kinetic helicity, i.e. it is based only on shear and current helicity fluxes, as first suggested by Vishniac & Cho (2001, ApJ 550, 752). Only above this threshold is the current helicity flux also able to alleviate catastrophic quenching. The fact that certain turbulence simulations have now shown apparently non‐resistively limited mean field saturation amplitudes may be suggestive of the current helicity flux having exceeded this critical value. Even below this critical value the field still reaches appreciable strength at the end of the kinematic phase, which is in qualitative agreement with dynamos in periodic domains. However, for large magnetic Reynolds numbers the field undergoes subsequent variations on a resistive time scale when, for long periods, the field can be extremely weak. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the meaning and inapplicability of the Zeldovich relations of magnetohydrodynamics
Authors: Blackman E. G. , Field G. B.
Published: June 2005

Considering a plasma with an initially weak large scale field subject to nonhelical turbulent stirring, Zeldovich (1957), for two‐dimensions, followed by others for three dimensions, have presented formulae of the form 〈b2〉 =f(RM)$ {\bar B}^2 $. Such “Zeldovich relations” have sometimes been interpreted to provide steady‐state relations between the energy associated with the fluctuating magnetic field and that associated with a large scale or mean field multiplied by a functionfthat depends on spatial dimension and a magnetic Reynolds numberRM. Here we dissect the origin of these relations and pinpoint pitfalls that show why they are inapplicable to realistic, dynamical MHD turbulence and that they disagree with many numerical simulations. For 2D, we show that when the total magnetic field is determined by a vector potential, the standard Zeldovich relation applies only transiently, characterizing a maximum possible value that the field energy can reach before necessarily decaying. In 3D, we show that the standard Zeldovich relations are derived by balancing subdominant terms. In contrast, balancing the dominant terms shows that the fluctuating field can grow to a value independent ofRMand the initially imposed$ \bar B $, as seen in numerical simulations. We also emphasize that these Zeldovich relations of nonhelical turbulence imply nothing about the amount mean field growth in a helical dynamo. In short, by re‐analyzing the origin of the Zeldovich relations, we highlight that they are inapplicable to realistic steady‐states of largeRMMHD turbulence. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A fuzzy logic‐based algorithm for cosmic‐ray hit rejection from single images
Authors: Shamir L.
Published: June 2005

An algorithm for cosmic‐ray rejection from single images is presented. The algorithm is based on modeling human perception using fuzzy logic. The proposed algorithm is specifically designed to reject multiple‐pixel cosmic ray hits that are larger than some of the point spread functions of the true astronomical sources. Experiments show that the algorithm can accurately reject ∼97.5% of the cosmic rays hits, while mistakenly rejecting 0.02% of the true astronomical sources. The major advantage of the presented algorithm is its computational efficiency. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scaling laws in decaying helical hydromagnetic turbulence
Authors: Christensson M. , Hindmarsh M. , Brandenburg A.
Published: June 2005

We study the evolution of growth and decay laws for the magnetic field coherence length ξ, energy EM and magnetic helicity H in freely decaying 3D MHD turbulence. We show that with certain assumptions, self‐similarity of the magnetic power spectrum alone implies that ξ ∼ t1/2. This in turn implies that magnetic helicity decays as H ∼ t–2s, where s = (ξdiff/ξH)2, in terms of ξdiff, the diffusion length scale, and ξH, a length scale defined from the helicity power spectrum. The relative magnetic helicity remains constant, implying that the magnetic energy decays as EM ∼ t–1/2–2s. The parameter s is inversely proportional to the magnetic Reynolds number ReM, which is constant in the self‐similar regime. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Revised equipartition and minimum energy formula for magnetic field strength estimates from radio synchrotron observations
Authors: Beck R. , Krause M.
Published: June 2005

The commonly used classical equipartition or minimum‐energy estimate of total magnetic fields strengths from radio synchrotron intensities is of limited practical use because it is based on the hardly known ratio K of the total energies of cosmic ray protons and electrons and also has inherent problems. We present a revised formula, using the number density ratio K for which we give estimates. For particle acceleration in strong shocks K is about 40 and increases with decreasing shock strength. Our revised estimate for the field strength gives larger values than the classical estimate for flat radio spectra with spectral indices of about 0.5–0.6, but smaller values for steep spectra and total fields stronger than about 10 µG. In very young supernova remnants, for example, the classical estimate may be too large by up to 10×. On the other hand, if energy losses of cosmic ray electrons are important, K increases with particle energy and the equipartition field may be underestimated significantly. Our revised larger equipartition estimates in galaxy clusters and radio lobes are consistent with independent estimates from Faraday rotation measures, while estimates from the ratio between radio synchrotron and X‐ray inverse Compton intensities generally give much weaker fields. This may be explained e.g. by a concentration of the field in filaments. Our revised field strengths may also lead to major revisions of electron lifetimes in jets and radio lobes estimated from the synchrotron break frequency in the radio spectrum. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaBoDS: The Garching‐Bonn Deep Survey
Authors: Erben T. , Schirmer M. , Dietrich J. P. , Cordes O. , Haberzettl L. , Hetterscheidt M. , Hildebrandt H. , Schmithuesen O. , Schneider P. , Simon P. , Deul E. , Hook R. N. , Kaiser N. , Radovich M. , Benoist C. , Nonino M. , Olsen L. F. , Prandoni I. , Wichmann R. , Zaggia S. , Bomans D. , Dettmar R. J. , Miralles J. M.
Published: June 2005

We present our image processing system for the reduction of optical imaging data from multi‐chip cameras. In the framework of the Garching Bonn Deep Survey (GaBoDS; Schirmer et al. 2003) consisting of about 20 square degrees of high‐quality data from WFI@MPG/ESO 2.2m, our group developed an imaging pipeline for the homogeneous and efficient processing of this large data set. Having weak gravitational lensing as the main science driver, our algorithms are optimised to produce deep co‐added mosaics from individual exposures obtained from empty field observations. However, the modular design of our pipeline allows an easy adaption to different scientific applications. Our system has already been ported to a large variety of optical instruments and its products have been used in various scientific contexts. In this paper we give a thorough description of the algorithms used and a careful evaluation of the accuracies reached. This concerns the removal of the instrumental signature, the astrometric alignment, photometric calibration and the characterisation of final co‐added mosaics. In addition we give a more general overview on the image reduction process and comment on observing strategies where they have significant influence on the data quality. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The stability of MHD Taylor‐Couette flow with current‐free spiral magnetic fields between conducting cylinders
Authors: Rüdiger G. , Hollerbach R. , Schultz M. , Shalybkov D. A.
Published: June 2005

We study the magnetorotational instability in cylindrical Taylor‐Couette flow, with the (vertically unbounded) cylinders taken to be perfect conductors, and with externally imposed spiral magnetic fields. The azimuthal component of this field is generated by an axial current inside the inner cylinder, and may be slightly stronger than the axial field. We obtain an instability beyond the Rayleigh line, for Reynolds numbers of order 1000 and Hartmann numbers of order 10, and independent of the (small) magnetic Prandtl number. For experiments withRout= 2Rin= 10 cm and Ωout= 0.27 Ωin, the instability appears for liquid sodium for axial fields of ∼20 Gauss and axial currents of ∼1200 A. For gallium the numbers are ∼50 Gauss and ∼3200 A. The vertical cell size is about twice the cell size known for nonmagnetic experiments. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Congenital diaphragmatic hernia: A retinoid‐signaling pathway disruption during lung development?
Authors: Gallot Denis , Marceau Geoffroy , Coste Karen , Hadden Hélène , Robert‐Gnansia Elisabeth , Laurichesse Hélène , Déchelotte Pierre J , Labbé André , Dastugue Bernard , Lémery Didier , Sapin Vincent
Published: June 2005

Congenital diaphragmatic hernia (CDH) usually occurs sporadically. The prognosis remains poor, with a 50% perinatal mortality rate. Most deaths result from hypoxemia due to lung hypoplasia and abnormal development of pulmonary vasculature that results in persistent pulmonary hypertension. Our current understanding of the pathogenesis of CDH is based on an assumption linking herniation of abdominal viscera into the thorax with compression of the developing lung. Pulmonary hypoplasia, however, can also result from reduced distension of the developing lung secondary to impaired fetal breathing movements. Moreover, a nitrofen‐induced CDH model shows that lung hypoplasia precedes the diaphragmatic defect, leading to a “dual‐hit hypothesis.” Recent data reveal the role of a retinoid‐signaling pathway disruption in the pathogenesis of CDH. We describe the clinical and epidemiological aspects of human CDH, the metabolic and molecular aspects of the retinoid‐signaling pathway, and the implications of retinoids in the development of the diaphragm and the lung. Finally, we highlight the existing links between CDH and disruption of the retinoid‐signaling pathway, which may suggest an eventual use of retinoids in the treatment of CDH. Birth Defects Research (Part A), 2005. © 2005 Wiley‐Liss, Inc.
Generating controlled molecular gradients in 3D gels
Authors: Rosoff W.J. , McAllister R. , Esrick M.A. , Goodhill G.J. , Urbach J.S.
Published: June 2005

A new method for producing molecular gradients of arbitrary shape in thin three dimensional gels is described. Patterns are produced on the surface of the gel by printing with a micropump that dispenses small droplets of solution at controlled rates. The molecules in the solution rapidly diffuse into the gel and create a smooth concentration profile that is independent of depth. The pattern is relatively stable for long times, and its evolution can be accurately described by finite element modeling of the diffusion equation. As a demonstration of the method, direct measurements of protein gradients are performed by quantitative fluorescence microscopy. A complementary technique for measuring diffusion coefficients is also presented. This rapid, flexible, contactless approach to gradient generation is ideally suited for cell culture experiments to investigate the role of gradients of diffusible substances in processes such as chemotaxis, morphogenesis, and pattern formation, as well as for high‐throughput screening of system responses to a wide range of chemical concentrations. © 2005 Wiley Periodicals, Inc.
Glucose metabolism at high density growth of E. coli B and E. coli K: Differences in metabolic pathways are responsible for efficient glucose utilization in E. coli B as determined by microarrays and northern blot analyses
Authors: Phue Je‐Nie , Noronha Santosh B. , Bhattacharyya Ritabrata , Wolfe Alan J. , Shiloach Joseph
Published: June 2005

The original article to which this Erratum refers was published in Biotechnol Bioeng 2005;90:805–820
Major upper gastrointestinal surgery is associated with an antigen-dependent proinflammatory T cell response
Authors: Sweeney K J , Kell M R , Ravi N , Reynolds J V
Published: June 2005

Background

T cells play a central role in the immune response to injury. Oesophageal and pancreatic resections are associated with significant risk of systemic inflammatory response syndrome and sepsis. This study involved a detailed analysis of T cell function in a consecutive cohort of patients undergoing such surgery.

Methods

Twenty-five patients undergoing major oncological upper gastrointestinal surgery were investigated for T cell expression of Fas and the activation markers CD69 and CD25, as well as interleukin (IL) 2, IL-10 and interferon (IFN) γ responses to stimulation with staphylococcal enterotoxin B (SEB). T cell activation in healthy volunteer peripheral blood mononuclear cells was studied in co-culture with patients' serum, either alone or with cytotoxic T lymphocyte-associated antigen (CTLA) 4, an inhibitor of antigen presentation.

Results

T cells expressed significantly raised levels of CD69 and CD25 after surgery, but no change in Fas expression was evident. There was a significant increase in the production of IL-2 after surgery without a concomitant increase in IFN-γ or IL-10 in response to SEB. Postoperative serum activated healthy volunteer T cells, a response that was inhibited (P = 0·053) by co-incubation with CTLA-4.

Conclusion

Major surgery results in pan-T cell activation via a serum-mediated antigenic mechanism that is independent of Fas expression. Postoperative T cells are primed for an augmented proinflammatory response to superantigen, sustained for at least 1 week, implicating the adaptive immune system in the development of the postoperative systemic immunoinflammatory state.
Comparison of Surgical Risk Score, POSSUM and p-POSSUM in higher-risk surgical patients
Authors: Brooks M J , Sutton R , Sarin S
Published: June 2005

Background

Much current interest is focused on the use of the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and the Portsmouth predictor equation (p-POSSUM) for risk-adjusted surgical audit. The Surgical Risk Score (SRS) has been shown to offer an equivalent accuracy, but was validated using a cohort that contained a high proportion of low-risk patients. The aim of this study was to compare the accuracy of mortality prediction using SRS with that of POSSUM and p-POSSUM in a cohort of higher-risk patients.

Methods

Some 949 consecutive patients undergoing inpatient surgical procedures in a district general hospital under the care of a single surgeon were analysed.

Results

The observed 30-day mortality rate was 8·4 per cent. Mean mortality rates predicted using SRS, POSSUM and p-POSSUM scores were 5·9, 12·6 and 7·3 per cent respectively. No significant difference was observed in the area under the receiver–operator characteristic curves for the three methods.

Conclusion

The SRS accurately predicted mortality in higher-risk surgical patients. The accuracy of prediction equalled that of POSSUM and p-POSSUM.
Development and validation of a reversed‐phase liquid chromatographic method for separation and simultaneous determination of COX‐2 inhibitors in pharmaceuticals and its application to biological ﬂuids
Authors: Nageswara Rao R. , Meena S. , Nagaraju D. , Raghu Ram Rao A.
Published: June 2005

An isocratic reversed‐phase high‐performance liquid chromatographic method has been developed for separation and simultaneous determination of COX‐2 inhibitors, viz., celecoxib, rofecoxib, valdecoxib, nimesulide and nabumetone, using 4‐chloro‐2‐nitroaniline as internal standard. Good chromatographic separation was achieved using a reversed‐phase Inertsil C18 column with mobile phase consisting of methanol and 0.05% aqueous glacial acetic acid (68:32 v/v) using photodiode array (PDA) detector at 230 nm. It was validated with respect to accuracy, precision, linearity, limit of detection and quantiﬁcation. The linearity range was found to be 1.0–20 µg/mL and the percentage recoveries were between 97.55 and 100.14. The method is suitable not only for the estimation of active ingredients in pharmaceutical dosage forms but also in vitro estimations in human plasma. It is simple, rapid, selective and capable of detecting and determining COX‐2 inhibitors with a detection limit of 0.127–1.040 µg/mL simultaneously. Copyright © 2004 John Wiley & Sons, Ltd.
Non‐aqueous capillary electrophoresis for simultaneous separation and determination of three major active components in traditional medicinal preparations
Authors: Li Cunhong , Zhang Jiyou , Chen Anjia , Xie Jianping , Chen Xingguo , Hu Zhide
Published: June 2005

A simple and sensitive non‐aqueous capillary electrophoresis method has been developed for simultaneous assay of three bioactive components (puerarin, daidzein and wogonin) in three traditional medicinal preparations for the ﬁrst time. Optimum separation of the analytes was obtained on a 47 cm × 75 µm i.d. capillary using a non‐aqueous buffer system of 20% acetonitrile, 25 mm ammonium acetate and apparent pH 9.00, with applied voltage and capillary temperature of 20 kV and 16°C, respectively. The relative standard deviations (RSDs) of the migration times and the peak areas of the three analytes were in the ranges 2.5–4.0% and 3.2–3.9%, respectively. Detection limits of puerarin, daidzein and wogonin were 0.090, 0.145 and 0.090 µg mL−1, respectively. In the tested concentration range, good linear relationships (correlation coefﬁcients: 0.9998 for puerarin, 0.9998 for daidzein and 0.9978 for wogonin) between peak areas and concentrations of the analytes were observed. This method has been successfully applied to simultaneous determination of the three bioactive components with recoveries from 91.0 to 114.0%. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of PbII on the Secondary Structure and Biological Activity of Trypsin
Authors: Yang Lin , Gao Zhiyong , Cao Ying , Xing Ruimin , Zhang Xiuying
Published: June 2005

The effects of PbII on the secondary structure and biological activity of trypsin have been examined by monitoring changes in its conductivity and IR and circular dichroism (CD) spectra. The results show that PbII reacts with trypsin, and that the binding sites might be OH and NH groups in pepsin. The CD spectra indicate that interaction with PbII significantly affects the secondary structure of trypsin, the β‐sheet‐structure content being increased by about 42 %, whilst those of α‐helix and β‐turn structures are decreased by 13 % and 21 %, respectively. The results clearly demonstrate that PbII affects the biological activity of trypsin by modifying its secondary structure. Most interesting is that PbII up‐regulates the activity of trypsin at low concentrations while down‐regulating it at high concentrations.
High‐Throughput Evaluation of Antioxidant and Pro‐oxidant Activities of Polyphenols with Thymidine Protection Assays
Authors: Meunier Stéphane , Hanédanian Mikaël , Desage‐El Murr Marine , Nowaczyk Stéphanie , Le Gall Thierry , Pin Serge , Renault Jean‐Philippe , Boquet Didier , Créminon Christophe , Mioskowski Charles , Taran Frédéric
Published: June 2005

A recently reported high‐throughput screening strategy has been applied to the rapid selection of new water‐soluble antioxidants that display strong protective activities. Based on a competitive immunoassay, a triple‐screening procedure was used to evaluate the ability of different compounds to protect thymidine under different oxidative stresses. The pro‐oxidant effect of norbadione A in the presence of iron was observed, while some pulvinic acid derivatives proved strongly protective during γ radiolysis, UV irradiation, and Fenton‐like oxidation.
An Inverse Substrate Orientation for the Regioselective Acylation of 3′,5′‐Diaminonucleosides Catalyzed by Candida antarctica lipase B?
Authors: Lavandera Iván , Fernández Susana , Magdalena Julia , Ferrero Miguel , Kazlauskas Romas J. , Gotor Vicente
Published: June 2005

Candida antarctica lipase B (CAL‐B) catalyzes the regioselective acylation of natural thymidine with oxime esters and also the regioselective acylation of an analogue, 3′,5′‐diamino‐3′,5′‐dideoxythymidine with nonactivated esters. In both cases, acylation favors the less hindered 5′‐position over the 3′‐position by upto 80‐fold. Computer modeling of phosphonate transition‐state analogues for the acylation of thymidine suggests that CAL‐B favors acylation of the 5′‐position because this orientation allows the thymine ring to bind in a hydrophobic pocket and forms stronger key hydrogen bonds than acylation of the 3′‐position. On the other hand, computer modeling of phosphonamidate analogues of the transition states for acylation of either the 3′‐ or 5′‐amino groups in 3′,5′‐diamino‐3′,5′‐dideoxythymidine shows similar orientations and hydrogen bonds and, thus, does not explain the high regioselectivity. However, computer modeling of inverse structures, in which the acyl chain binds in the nucleophile pocket and vice versa, does rationalize the observed regioselectivity. The inverse structures fit the 5′‐, but not the 3′‐intermediate thymine ring, into the hydrophobic pocket, and form a weak new hydrogen bond between the O‐2 carbonyl atom of the thymine and the nucleophile amine only for the 5′‐intermediate. A water molecule might transfer a proton from the ammonium group to the active‐site histidine. As a test of this inverse orientation, we compared the acylation of thymidine and 3′,5′‐diamino‐3′,5′‐dideoxythymidine with butyryl acyl donors and with isosteric methoxyacetyl acyl donors. Both acyl donors reacted at equal rates with thymidine, but the methoxyacetyl acyl donor reacted four times faster than the butyryl acyl donor with 3′,5′‐diamino‐3′,5′‐dideoxythymidine. This faster rate is consistent with an inverse orientation for 3′,5′‐diamino‐3′,5′‐dideoxythymidine, in which the ether oxygen atom of the methoxyacetyl group can form a similar hydrogen bond to the nucleophilic amine. This combination of modeling and experiments suggests that such lipase‐catalyzed reactions of apparently close substrate analogues like alcohols and amines might follow different pathways.
Chemical Synthesis of a Dual Branched Malto‐Decaose: A Potential Substrate for α‐Amylases
Authors: Damager Iben , Jensen Morten T. , Olsen Carl E. , Blennow Andreas , Møller Birger L. , Svensson Birte , Motawia Mohammed S.
Published: June 2005

A convergent block strategy for general use in efficient synthesis of complex α‐(1→4)‐ and α‐(1→6)‐malto‐oligosaccharides is demonstrated with the first chemical synthesis of a malto‐oligosaccharide, the decasaccharide 6,6′′′′‐bis(α‐maltosyl)‐maltohexaose, with two branch points. Using this chemically defined branched oligosaccharide as a substrate, the cleavage pattern of seven different α‐amylases were investigated. α‐Amylases from human saliva, porcine pancreas, barley α‐amylase 2 and recombinant barley α‐amylase 1 all hydrolysed the decasaccharide selectively. This resulted in a branched hexasaccharide and a branched tetrasaccharide. α‐Amylases from Asperagillus oryzae, Bacillus licheniformis and Bacillus sp. cleaved the decasaccharide at two distinct sites, either producing two branched pentasaccharides, or a branched hexasaccharide and a branched tetrasaccharide. In addition, the enzymes were tested on the single‐branched octasaccharide 6‐α‐maltosyl‐maltohexaose, which was prepared from 6,6′′′′‐bis(α‐maltosyl)‐maltohexaose by treatment with malt limit dextrinase. A similar cleavage pattern to that found for the corresponding linear malto‐oligosaccharide substrate was observed.
LanGT2 Catalyzes the First Glycosylation Step during Landomycin A Biosynthesis
Authors: Luzhetskyy Andriy , Taguchi Takaaki , Fedoryshyn Marta , Dürr Clemens , Wohlert Sven‐Eric , Novikov Volodymyr , Bechthold Andreas
Published: June 2005

The glycosyltransferase LanGT2 is involved in the biosynthesis of the hexasaccharide side chain of the angucyclic antibiotic landomycin A. Its function was elucidated by targeted gene inactivation of lanGT2. The main metabolite of the obtained mutant was identified as tetrangulol (4), the progenitor of the landomycin aglycon (7). The lack of the sugar side chain indicates that LanGT2 catalyzes the priming glycosyl transfer in the hexasaccharide biosynthesis: the attachment of a D‐olivose to O‐8 of the polyketide backbone. Heterologous expression of urdGT2 from S. fradiae Tü2717 in this mutant resulted in the production of a novel C‐glycosylated angucycline (6).
Metabolic Engineering of Aminocoumarins: Inactivation of the Methyltransferase Gene cloP and Generation of New Clorobiocin Derivatives in a Heterologous Host
Authors: Freitag Anja , Rapp Heike , Heide Lutz , Li Shu‐Ming
Published: June 2005

Aminocoumarin antibiotics are highly potent inhibitors of bacterial gyrase and represent a class of antibiotics that are very suitable for the generation of new compounds by metabolic engineering. In this study, the putative methyltransferase gene cloP in the biosynthetic gene cluster of clorobiocin was inactivated. Expression of the modified gene cluster in the heterologous host Streptomyces coelicolor M512 gave three new aminocoumarin antibiotics. The structures of the new compounds were elucidated by MS and 1H NMR, and their antibacterial activities were determined. All three compounds lacked clorobiocin's methyl group at 4‐OH of the deoxysugar moiety, noviose. They differed from each other in the position of the 5‐methylpyrrole‐2‐carbonyl group, which was found to be attached to either 2‐OH, 3‐OH or 4‐OH of noviose. Attachment at 4‐OH resulted in the highest antibacterial activity. This is the first time that an aminocoumarin antibiotic acylated at 4‐OH in noviose has been detected.
An Enzyme Module System for the Synthesis of dTDP‐activated Deoxysugars from dTMP and Sucrose
Authors: Elling Lothar , Rupprath Carsten , Günther Nicole , Römer Ulrike , Verseck Stefan , Weingarten Petra , Dräger Gerald , Kirschning Andreas , Piepersberg Wolfgang
Published: June 2005

A flexible enzyme module system is presented that allows preparative access to important dTDP‐activated deoxyhexoses from dTMP and sucrose. The strategic combination of the recombinant enzymes dTMP‐kinase and sucrose synthase (SuSy), and the enzymes RmlB (4,6‐dehydratase), RmlC (3,5‐epimerase) and RmlD (4‐ketoreductase) from the biosynthetic pathway of dTDP‐β‐L‐rhamnose was optimized. The SuSy module (dTMP‐kinase, SuSy, ±RmlB) yielded the precursor dTDP‐α‐D‐glucose (2) or the biosynthetic intermediate dTDP‐6‐deoxy‐4‐keto‐α‐D‐glucose (3) on a 0.2–0.6 g scale with overall yields of 62 % and 72 %, respectively. A two‐step strategy in which the SuSy module was followed by the deoxysugar module (RmlC and RmlD) resulted in the synthesis of dTDP‐β‐L‐rhamnose (4; 24.1 μmol, overall yield: 35.9 %). Substitution of RmlC by DnmU from the dTDP‐β‐L‐daunosamine pathway of Streptomyces peucetius in this module demonstrated that DnmU acts in vitro as a 3,5‐epimerase with 3 as substrate to yield 4 (32.2 μmol, overall yield: 44.7 %). Chemical reduction of 3 with NaBH4 gave a mixture of the C‐4 epimers dTDP‐α‐D‐quinovose (6) and dTDP‐α‐D‐fucose (7) in a ratio of 2:1. In summary, the modular character of the presented enzyme system provides valuable compounds for the biochemical characterization of deoxysugar pathways playing a major role in microbial producers of antibiotic and antitumour agents.