bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of Recycled Polymer Blends with Activated Natural Zeolite
Authors: Djoumaliisky Strashimir , Zipper Peter
Published: November 2004

The growing interest in the natural zeolite is based on some specific peculiarities of its structure, which after dehydration enables adsorption processes of some polymer molecules and/or segments to take place on the zeolite surface. The main goal of the study is to investigate the effect of dehydrated zeolite on the flow behavior, mechanical properties and morphology of immiscible blends from unsorted polymer wastes. A tetra‐component blend consisting of 40 wt.% polypropylene (PP), 40 wt.% high‐density polyethylene (HDPE), 15 wt.% low‐density polyethylene (LDPE) and 5 wt.% polystyrene (PS), was studied as a model system of commingled plastic wastes. Compositions from recycled blend and dehydrated zeolite in a wide concentration range (from 0 to 20 wt.%) were prepared using a twin‐screw extruder Brabender DSE 35/17D in the temperature range from 140 to 190 °C. The compositions were characterized by capillary rheometry, differential scanning calorimetry (DSC), site‐resolved wide‐angle X‐ray scattering (WAXS) and mechanical tests. The results show a compatibilizing effect of dehydrated zeolite at low concentration levels (1‐2 wt.%) and open wide possibilities for utilization of dehydrated zeolite in the recycling of unsorted polymer wastes.
Influence of Talc and SEBS‐g‐MA on PP/SEBS‐g‐MA/Talc Composites under Gamma Irradiation Sterilization Conditions
Authors: Denac Matjaž , Musil Vojko , Ranogajec Franjo , Šmit Ivan
Published: November 2004

Among thermoplastics, polypropylene is outstanding with respect to its attractive combination of low cost, low weight, heat distortion temperature above 100°C, and extraordinary versatility in terms of properties and applications. With the appropriate modification, it is possible to improve the existing properties of the polypropylene, or even obtain the new ones. As a result of its originally superior properties, polypropylene is commonly used in medical purposes, where it has to undergo the process of sterilization beforehand. The sterilization of the polypropylene in medicine is most often being carried out with low dose of gamma irradiation, which can influence the changes of properties of both the polymeric matrix and modifiers. Therefore, the purpose of our research work was to determine the mechanical properties of unirradiated and gamma irradiated isotactic polypropylene (iPP) composites with talc filler and poly‐(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) block copolymer, grafted with maleic anhydride (SEBS‐g‐MA) as elastomeric modifier, as well as of corresponding binary blends. Unirradiated and gamma irradiated composites and blends were characterized by tensile measurements, measurements of notched impact strength and FTIR spectroscopy. The effects of composition and gamma irradiation on the properties of the iPP composites and blends are discussed, with emphasis on the study of the stabilizing effect of talc in irradiated iPP composites.
Approximate boundary controllability for the system of linear elasticity
Authors: Łada Andrzej , Sidz Leszek
Published: November 2004

The approximate controllability for variable coefficients, isotropic, evolution elasticity system is considered. The appropriate unique continuation theorem for solutions of the system is stated. Copyright © 2004 John Wiley & Sons, Ltd.
Phantom design method for high‐field MRI human systems
Authors: Yang Qing X. , Wang Jinghua , Collins Christopher M. , Smith Michael B. , Zhang Xiaoliang , Ugurbil Kamil , Chen Wei
Published: November 2004

A phantom design method suitable for high‐field MRI based on the RF field wave characteristics of sample and experimental validations at 7.0 T and 3.0 T are presented. The RF field distribution in a phantom with a given RF coil system is primarily determined by the sample size relative to the wavelength inside the sample, and the ratio between the displacement and conduction currents. Experimental results demonstrate that the MR image intensity patterns associated with wave behavior in human samples at a given field strength can be reproduced with a phantom at the same or different field strengths once the dimension and penetration constant are scaled by the corresponding wavelength in the sample medium. Magn Reson Med 52:1016–1020, 2004. © 2004 Wiley‐Liss, Inc.
Localized 7Li MR spectroscopy: In vivo brain and serum concentrations in the rat
Authors: Pearce John M. , Lyon Melvin , Komoroski Richard A.
Published: November 2004

The brain concentration of lithium (Li) in treated rats was measured using a recently developed method based on in vivo 7Li PRESS localized MRS. Comparison was made to the corresponding serum concentration at two treatment durations. The brain and serum Li concentrations were highly correlated with each other, more so than found previously for humans. The brain and serum Li concentrations also correlated with dose. Both the brain Li concentration and the serum concentration at 16.1 days of treatment correlated with the corresponding measure at 6.6 days. After correction of the brain Li concentrations for reduced 7Li MRS visibility, the mean brain/serum Li ratio for rats was close to unity, unlike most previous values found for humans. However, in some individual cases the ratio deviated substantially from the mean, suggesting that serum Li is not always a reliable indicator of brain Li. Magn Reson Med 52:1087–1092, 2004. © 2004 Wiley‐Liss, Inc.
Dynamic lung morphology of methacholine‐induced heterogeneous bronchoconstriction
Authors: Chen Ben T. , Johnson G. Allan
Published: November 2004

Hyperpolarized (HP) 3helium (3He) dynamic MRI was used to investigate airway response in rats following intravenous (i.v.) bolus administration of a contractile agent, methacholine (MCh). The method provides direct visualization of the ventilated regions within the lung. Heterogeneous bronchoconstriction following the i.v. MCh injection was evident using this technique. These 3He dynamic lung images revealed that the inspired fresh air was shunted to the less‐constricted regions after the MCh challenge in a similar manner as described by Laplace's relationship for the stability between adjacent alveoli. The airways in the more‐constricted regions became nearly closed, resulting in air trapping, while the airways in the less‐constricted regions remained effectively open, leading to overinflation. These data suggest a lung model of airway constriction partitioned into ventilated and nonventilated regions. These nonventilated regions are heterogeneously distributed in the lung and this distribution cannot be deduced from spirometric measurement of the whole lung. We demonstrate that a combination of functional 3He images and anatomical 1H images provide an effective method to diagnose regional lung abnormalities in rats. Magn Reson Med 52:1080–1086, 2004. © 2004 Wiley‐Liss, Inc.
Quantitative analysis of diffusion tensor orientation: Theoretical framework
Authors: Wu Yu‐Chien , Field Aaron S. , Chung Moo K. , Badie Benham , Alexander Andrew L.
Published: November 2004

Diffusion‐tensor MRI (DT‐MRI) yields information about the magnitude, anisotropy, and orientation of water diffusion of brain tissues. Although white matter tractography and eigenvector color maps provide visually appealing displays of white matter tract organization, they do not easily lend themselves to quantitative and statistical analysis. In this study, a set of visual and quantitative tools for the investigation of tensor orientations in the human brain was developed. Visual tools included rose diagrams, which are spherical coordinate histograms of the major eigenvector directions, and 3D scatterplots of the major eigenvector angles. A scatter matrix of major eigenvector directions was used to describe the distribution of major eigenvectors in a defined anatomic region. A measure of eigenvector dispersion was developed to describe the degree of eigenvector coherence in the selected region. These tools were used to evaluate directional organization and the interhemispheric symmetry of DT‐MRI data in five healthy human brains and two patients with infiltrative diseases of the white matter tracts. In normal anatomical white matter tracts, a high degree of directional coherence and interhemispheric symmetry was observed. The infiltrative diseases appeared to alter the eigenvector properties of affected white matter tracts, showing decreased eigenvector coherence and interhemispheric symmetry. This novel approach distills the rich, 3D information available from the diffusion tensor into a form that lends itself to quantitative analysis and statistical hypothesis testing. Magn Reson Med 52:1146–1155, 2004. © 2004 Wiley‐Liss, Inc.
Correction of high‐order eddy current induced geometric distortion in diffusion‐weighted echo‐planar images
Authors: Shen Yuji , Larkman David J. , Counsell Serena , Pu Ida M. , Edwards David , Hajnal Joseph V.
Published: November 2004

Diffusion‐weighted images acquired with the echo‐planar imaging technique are highly sensitive to eddy current induced geometric distortions that vary with the magnitude and direction of the diffusion sensitizing gradients. Such distortions cause misalignment of images acquired with different diffusion strengths and orientations. This in turn can result in errors when calculating maps of the apparent diffusion coefficient and diffusion tensor. Previous correction methods either require separate calibration data or only deal with low‐order errors. In this study, we demonstrate a method that can correct for higher‐order errors. The method relies on collecting pairs of images with diffusion sensitizing gradients reversed. This paired data are first corrected for shifts and linear distortion and then combined to cancel higher‐order errors. All acquired data contribute to the final results. The method has been tested by simulation, on phantoms, on adult volunteers, and on neonatal brain examinations. Magn Reson Med 52:1184–1189, 2004. © 2004 Wiley‐Liss, Inc.
Modeling and analyzing multiple station baggage screening security system performance
Authors: Jacobson Sheldon H. , McLay Laura A. , Kobza John E. , Bowman Jon M.
Published: November 2004

In the aftermath of the tragic events of 11 September 2001, numerous changes have been made to aviation security policy and operations throughout the nation's airports. The allocation and utilization of checked baggage screening devices is a critical component in aviation security systems. This paper formulates problems that model multiple sets of flights originating from multiple stations (e.g., airports, terminals), where the objective is to optimize a baggage screening performance measure subject to a finite amount of resources. These measures include uncovered flight segments (UFS) and uncovered passenger segments (UPS). Three types of multiple station security problems are identified and their computational complexity is established. The problems are illustrated on two examples that use data extracted from the Official Airline Guide. The examples indicate that the problems can provide widely varying solutions based on the type of performance measure used and the restrictions imposed by the security device allocations. Moreover, the examples suggest that the allocations based on the UFS measure also provide reasonable solutions with respect to the UPS measure; however, the reverse may not be the case. This suggests that the UFS measure may provide more robust screening device allocations. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005.
Potentiation of (DL)‐3,4‐methylenedioxymethamphetamine (MDMA)‐induced toxicity by the serotonin 2A receptior partial agonist d‐lysergic acid diethylamide (LSD), and the protection of same by the serotonin 2A/2C receptor antagonist MDL 11,939
Authors: Armstrong Brian D. , Paik Elena , Chhith Seririthanar , Lelievre Vincent , Waschek James A. , Howard Sherrel G.
Published: November 2004

To elucidate the role of the serotonin (5‐HT)2A/2C receptors in 3,4‐methylenedioxymethamphetamine (MDMA)‐induced neurotoxicity, MDMA was administered to rats and the presence of the serotonin transporter (5‐HTT) was assessed at the protein level with immunohistochemistry (IHC), and the RNA level with a Northern blotting technique. d‐lysergic acid diethylamide (LSD) and MDL 11,939 were given in conjunction with MDMA in order to assess the importance of 5‐HT receptors in MDMA‐induced neurotoxicity. The hypothesis is that the MDMA + LSD‐treated animals should have more neurotoxicity as measured by loss of 5‐HTTs compared to the MDMA‐treated animals. Moreover, the loss of 5‐HTTs should be attenuated in animals given the combination of MDMA + MDL 11,939, as the latter drug is a selective 5‐HT2A/2C antagonist. The results showed that MDMA‐induced neurotoxicity was dose dependently increased by LSD. Moreover, the drug MDL 11,939 attenuated MDMA‐induced neurotoxicity, suggesting that 5‐HT2A/2C receptors are involved in MDMA‐induced neurotoxicity.
Effect of two different cytoprotectives, ethiofos and β‐NGF, on cisplatin‐induced toxicity in Schwann cell cultures; a preliminary study
Authors: Jirsová K. , Mandys V. , Bär P.R.
Published: November 2004

Two cytoprotective agents, ethiofos (WR2721) and nerve growth factor (NGF), were used to diminish cisplatin‐induced toxicity in Schwann cell cultures. The effect of both studied agents was estimated by a micronucleus test and the comet assay. The comet assay was performed in cultured human Schwann cells isolated from sural nerve biopsies, and the micronucleus test was used in primary cultures of Schwann cells isolated from foetal rat dorsal root ganglia (DRG). A dose‐dependent increase in the number of cells displaying DNA damage was found at both concentrations of cisplatin, 0.5 and 1.0 μM. No significant protective effect of either β‐NGF or WR‐2721 was observed in human Schwann cell cultures. A significant protective effect was obtained in the cultures of Schwann cells isolated from foetal rat DRG, when treated simultaneously with 0.5 μM cisplatin and 10 ng/ml β‐NGF. WR‐2721 was not effective in these cells.
Effects of 5‐HT1 receptor agonist on the excitability of medial vestibular nuclear neurons
Authors: Park Jong‐Seong , Jeong Han‐Seong , Kim Tae‐Sun , Kim Yo‐Sik , Kim Jae‐Ha , Jang Myung‐Joo , Kim Ja‐Yeon , Huang Mei
Published: November 2004

The aim of this study is to explore the action of 5‐HT1 receptor on spontaneous firing activity of the rat medial vestibular nuclear neurons by patch clamp experiments. The spontaneous firing was increased in 45.5% and decreased in 54.5% of the neurons tested with 5‐carboxamidotryptamine, non‐selective 5‐HT1 receptor agonist. And the whole potassium currents of medial vestibular nuclear neurons was decreased in 64% and increased in 36% of cells tested with 5‐carboxamidotryptamine. The spontaneous firing rate was increased by 8‐OH‐DPAT, selective 5‐HT1A receptor agonist in 73.3% and was not changed in 26.7%. Whole potassium currents were decreased in 84.2% and was not affected in 15.8% by 8‐OH‐DPAT. These results suggest that 5‐HTIA receptor of the medial vestibular nuclear neurons mediates excitatory effects whereas inhibitory effects are mediated by other 5‐HT1 receptors.
Ouabain‐induced reversal of astrocytic GLT‐1 crucial to neuronal death in neuron/astrocyte co‐cultures
Authors: Tanaka Motoki , Kawahara Koichi , Hosoya Rui , Kosugi Tatsuro , Nakajima Takayuki , Yamada Takeshi
Published: November 2004

We investigated whether the role of the astrocytic glutamate transporter GLT‐1 is reversed when the ionic gradient across plasma membrane has collapsed, and if so, whether the reversal is crucial to neuronal death. To estimate the direction of glutamate transport by GLT‐1, Na+ movement coupled with glutamate transport in astrocytes was analyzed in mixed astrocyte/neuron cultures. The rise in astrocytic intracellular Na+ due to glutamate exposure was suppressed by co‐treatment with dihydrokainate (DHK). In contrast, the ouabain‐induced rise in Na+ was significantly enhanced by DHK, suggesting that the role of GLT‐1 was reversed. We then analyzed whether the reversal increased the amount of extracellular glutamate, and was crucial to excitotoxic neuronal death. Ouabain treatment resulted in a marked rise in glutamate and in neuronal death, and both the rise and cell death were significantly attenuated by DHK treatment.
A general effective method for combining collocation and DDM: An application of discontinuous Galerkin methods
Authors: Herrera Ismael , Yates Robert
Published: November 2004

Domain decomposition methods (DDM) have received much attention in recent years. They constitute the most effective means of using parallel computing resources to model continuous systems. However, combining collocation procedures with domain decomposition methods presents complications that must be overcome in order to profit from the advantages of parallel computing. The present paper belongs to a line of research in which a theory that constitutes a general and systematic formulation of discontinuous Galerkin methods (dG) is being investigated. Based on it, a new method of collocation of general applicability, TH‐collocation, was recently introduced. For a broad class of symmetric and positive continuous systems, TH‐collocation yields symmetric and positive matrices. This clears the way for applying effectively DDM and parallel computing, in combination with collocation, to such systems. In this paper the general procedure is explained with some detail and then is applied to develop an effective method for processing elliptic equations of second order. This, by the way, overcomes the difficulties encountered in a previous Herrera and Pinder's article. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005.
The great auk (Pinguinus impennis) in the Netherlands during the Roman period
Authors: Groot M.
Published: November 2004

Bones of the great auk (Pinguinus impennis) have been found in four archaeological sites in the Netherlands in recent years. These sites all date to the early Roman period. The great auk is believed never to have been a breeding bird in the Netherlands, which makes the presence of the bones remarkable. The history and ecology of the great aukare outlined. Some possible reasons are discussed for the presence of the great auk in Dutch waters during the early Roman period. Copyright © 2004 John Wiley & Sons, Ltd.
Robust continuous‐time controller design via structural Youla–Kučera parameterization with application to predictive control
Authors: Kowalczuk Z. , Suchomski P.
Published: November 2004

This paper addresses the continuous‐time control of uncertain linear SISO plants and its nominal and robust stability and nominal and robust performance objectives. A specific application of the Youla–Kučera (Q) parameterization concept leads to a new development of observer‐like controller structures. This method is combined with a nominal design of continuous‐time generalized predictive control suitable for both minimum‐phase and non‐minimum‐phase plants. The subsequent design procedure consists of two steps. Firstly, the nominal stability and nominal performance of the control system are established by using an analytical design methodology, based on a collection of closed‐loop prototype characteristics with definite time‐domain specifications. And secondly, a generic structure of the controller is enhanced by suitable Q‐parameters guaranteeing that the control system has the required robustness properties. The proposed structural (reduced‐order) Q‐parameterization relies on an observer structure of controllers, which can be easily enhanced with certain filters necessary for control robustification. To reduce the complexity of the resulting robust controllers, we suggest using a structural factorization, which allows for simple forms of robustifying (phase‐lag) correctors of low order, easy for implementation, and convenient for optimization and tuning. Two numerical examples are given to illustrate the composed technique and its practical consequences. Copyright © 2004 John Wiley & Sons, Ltd.
Mean‐risk optimization of electricity portfolios
Authors: Eichhorn Andreas , Gröwe‐Kuska Nicole , Liebscher Andrea , Römisch Werner , Spangardt Gorden , Wegner Isabel
Published: November 2004

We present a mathematical model with stochastic input data for mean‐risk optimization of electricity portfolios containing several physical components and energy derivative products. The model is designed for the optimization horizon of one year in hourly discretization. The aim consists in maximizing the mean book value of the portfolio at the end of the optimization horizon and, at the same time, in minimizing the risk of the portfolio decisions. The risk is measured by the conditional value‐at‐risk and by some multiperiod extension of CVaR, respectively.We present numerical results for a large‐scale realistic problem adapted to a municipal power utility and study the effects of varying weighting of risk. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parallel Strategies Applied to FE Simulations of Multiphasic Problems
Authors: Ehlers Wolfgang , Graf Tobias , Ammann Martin , Wieners Christian
Published: November 2004

While the theoretical background of various porous media models is well understood, it is still a demanding task to deal with these models numerically. In this contribution, a triphasic model is presented, which is capable of describing partially saturated soils. In quasi‐static conditions, this model results in the primary variables solid displacement, pore‐liquid pressure and pore‐gas pressure. For a stable numerical implementation, Taylor‐Hood elements are required, which need quadratic ansatz functions for the displacement and linear ansatz functions for the pressure terms. Looking at numerical simulations in 2‐d, challenging finite element calculations have already been realized in combination with adaptivity in time and space [1]. Nevertheless, new strategies have to be considered for a realization of applications of the model in 3‐d in order to handle the huge amount of unknowns arising from the discretization with Taylor‐Hood elements. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some Remarks on Modelling and Simulation of Thin Film Flow
Authors: Becker Jürgen , Grün Günther
Published: November 2004

Recenty, convergent and nonnegativity preserving numerical schemes for the thin film equation have been developed and applied successfully to model the flow of thin films of Newtonian liquids on homogeneous surfaces. It is the aim of this paper to discuss two related, but more involved physical settings. The first topic is flow on chemically structured surfaces which is of great interest in a number of microfluidic applications. We will formulate a convergent, nonnegativity preserving scheme and compare the simulations with recent physical experiments. The second part deals with power‐law‐fluids. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modified carrageenan. 5. Preparation, swelling behavior, salt‐ and pH‐sensitivity of partially hydrolyzed crosslinked carrageenan‐graft‐polymethacrylamide superabsorbent hydrogel
Authors: Pourjavadi A. , Sadeghi M. , Hosseinzadeh H.
Published: November 2004

The polysaccharide, kappa‐carrageenan (κC) was chemically modified to achieve a novel superabsorbent hydrogel via graft copolymerization of methacrylamide (MAM) onto the substrate followed by alkaline hydrolysis. Ammonium persulfate (APS) and N,N′‐methylene bisacrylamide (MBA) were used as a free‐radical initiator and a crosslinker, respectively. The saponification reaction was carried out using sodium hydroxide aqueous solution. Either κC‐g‐PMAM or hydrolyzed κC‐g‐PMAM (PMAM: polymethacrylamide) was characterized by FT‐IR spectroscopy. The effect of grafting variables (i.e. concentration of MBA, MAM, and APS) and alkaline hydrolysis conditions (i.e. NaOH concentration, hydrolysis time and temperature) were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The swelling capacity of these hydrogels was also measured in various salt solutions. Results indicated that the swelling ratios decreased with an increase in the ionic strength of the salt solutions. This behavior can be attributed to charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. Absorbency of superabsorbing hydrogels was examined in buffer solutions with pH range 1–13. Also, the pH reversibility and on–off switching behavior, at pH values 3.0 and 8.0, makes the synthesized hydrogels good candidates for controlled delivery of bioactive agents. Finally, swelling kinetics in distilled water and various salt solutions was preliminary investigated. Results showed that the swelling in water was faster than in saline solutions. Copyright © 2004 John Wiley & Sons, Ltd.
UV curable waterborne polyurethane acrylate dispersions based on hyperbranched aliphatic polyester: effect of molecular structure on physical and thermal properties
Authors: Asif Anila , Shi Wenfang
Published: November 2004

A novel waterborne hyperbranched polyurethane acrylate for aqueous dispersions (WHPUDs) based on hydroxy‐functionalized hyperbranched aliphatic polyester Boltorn™ H20 was investigated. The effects of structural composition and crosslinking density have been studied in terms of swellability by water, thermal degradation, viscosity changes as well as transmission electron microscopy (TEM) morphology. The swell ratio showed an increasing trend with the higher concentration of ionic group, which is due to the increased total surface area of particles. The results of thermogravimetric analysis (TGA) for cured WHPUD films indicated good thermal stability with no appreciable weight loss until 200°C. The activation energies were evaluated and were found in the range 154–186 kJ mol−1. It was observed that an increase in hard segment content provoked the increases in thermal degradation temperature and activation energy of waterborne dispersions. The transmission electron photographs revealed that the average particle sizes of aqueous dispersions were in the range 30–125 nm. Owing to the enlargement of the stabilization site, the particle size decreased as the content of carboxyl group and degree of neutralization increased. The viscosity of WHPUDs increased rapidly with increasing the degree of neutralization. Moreover, water showed a favorable viscosity reduction effect. Copyright © 2004 John Wiley & Sons, Ltd.
Hereditary haemolytic anaemias: unexpected sequelae of mutations in the genes for erythroid membrane skeletal proteins
Authors: Birkenmeier Connie S , Barker Jane E
Published: November 2004

Although the haemolytic anaemia may be the primary concern for hereditary spherocytosis and elliptocytosis patients, it is clear that their situation can be compromised by primary and secondary defects in erythroid and non‐erythroid systems of the body. All seven of the red cell membrane skeletal proteins discussed in this review are also expressed in non‐erythroid tissues, and mutations in their genes have the potential to cause non‐erythroid defects. In some instances, such as the protein 4.1R and ANK1 neurological deficits, the diagnosis is clear. In other instances, because of the complex expression patterns involved, the non‐erythroid effects may be difficult to assess. An example is the large multidomain, multifunctional band 3 protein. In this case, the location of the mutation can cause defects in one functional domain or isoform and not the other. In other cases, such as the beta‐adducin null mutation, other isoforms may partially compensate for the primary deficiency. In such cases, it may be that the effects of the deficit are subtle but could increase under stress or with age. To be completely successful, treatment strategies must address both primary and secondary effects of the anaemia. If gene replacement therapy is to be used, the more that is known about the underlying genetic mechanisms producing the multiple isoforms the better we will be able to design the best replacement gene. The various animal models that are now available should be invaluable in this regard. They continue to contribute to our understanding of both the primary and the secondary effects and their treatment. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
The pathobiology of the septin gene family
Authors: Hall Peter A , Russell SE Hilary
Published: November 2004

Septins are an evolutionarily conserved group of GTP‐binding and filament‐forming proteins that belong to the large superclass of P‐loop GTPases. While originally discovered in yeast as cell division cycle mutants with cytokinesis defects, they are now known to have diverse cellular roles which include polarity determination, cytoskeletal reorganization, membrane dynamics, vesicle trafficking, and exocytosis. Septin proteins form homo‐ and hetero‐oligomeric polymers which can assemble into higher‐order filaments. They are also known to interact with components of the cytoskeleton, ie actin and tubulin. The precise role of GTP binding is not clear but a current model suggests that it is associated with conformational changes which alter binding to other proteins. There are at least 12 human septin genes, and although information on expression patterns is limited, most undergo complex alternative splicing with some degree of tissue specificity. Nevertheless, an increasing body of data implicates the septin family in the pathogenesis of diverse disease states including neoplasia, neurodegenerative conditions, and infections. Here the known biochemical properties of mammalian septins are reviewed in the light of the data from yeast and other model organisms. The data implicating septins in human disease are considered and a model linking these data is proposed. It is posited that septins can act as regulatable scaffolds where the stoichiometry of septin associations, modifications, GTP status, and the interactions with other proteins allow the regulation of key cellular processes including polarity determination. Derangements of such septin scaffolds thus explain the role of septins in disease states. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Laminopathies
Authors: Broers Jos LV , Hutchison Chris J , Ramaekers Frans CS
Published: November 2004

Nuclear lamins form a fibrous nucleoskeletal network of intermediate‐sized filaments that underlies the inner nuclear membrane. It associates with this membrane through interactions with specific integral nuclear membrane proteins, while within this flattened lamin lattice the nuclear pore complexes are embedded. Next to this peripheral network, the lamins can form intranuclear structures. The lamins are the evolutionary progenitors of the cytoplasmic intermediate filament proteins and have profound influences on nuclear structure and function. These influences require that lamins have dynamic properties and dual identities as structural building blocks on the one hand, and transcription regulators on the other. Which of these identities underlies the laminopathies, a myriad of genetic diseases caused by mutations in lamins or lamin‐associated proteins, is a topic of intense debate. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Hepatocyte growth factor (HGF) downregulates thrombospondin 1 (TSP‐1) expression in thyroid papillary carcinoma cells
Authors: Scarpino Stefania , Di Napoli Arianna , Taraboletti Giulia , Cancrini Antonio , Ruco Luigi P
Published: November 2004

This study investigates the expression of thrombospondin‐1 in papillary carcinoma of the thyroid and the role of Met–HGF interaction in TSP‐1 regulation. In tissue sections, immunostaining for TSP‐1 was associated with the fibrous tumour stroma, and showed areas of marked intensity adjacent to the basal membrane of tumour cells. Investigation of TSP‐1 RNA expression showed that, in 10 of 14 cases, TSP‐1 mRNA levels were significantly lower in tumour tissue (20–100% reduction; mean = 55% ± 20; p = 0.001) than in the corresponding normal thyroid. Since it has been reported that HGF can downregulate the expression of TSP‐1 mRNA, TSP‐1 mRNA levels were measured in 7 primary cultures, established from thyroid papillary carcinomas (TPC), and in 1 TPC cell line prior to, or after, stimulation with HGF. A marked decrease in TSP‐1 mRNA levels was observed after HGF stimulation in 6/7 primary cultures (60–100% decrease (mean = 79 ± 15%; p = 0.006) and in the TPC cell line; moreover, the decrease in TSP‐1 mRNA in cell extracts was associated with a decrease in TSP‐1 protein in culture supernatants. The HGF activity was dose dependent and the downregulation lasted for at least 48 h after stimulation. The high‐level expression of Met protein, the high‐affinity receptor for HGF, in most cases of papillary carcinoma of the thyroid is consistent with the possibility that HGF–Met interaction plays a crucial role in regulating the expression of TSP‐1 in this tumour type. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Evaluation of fetal cardiac contractility by two‐dimensional ultrasonography
Authors: Goldinfeld Michael , Weiner Ehud , Peleg David , Shalev Eliezer , Ben‐Ami Moshe
Published: November 2004

Objective

Evaluation of fetal cardiac contractility by two‐dimensional ultrasonography and construction of nomograms of area shortening fraction, end‐diastolic area and end‐systolic area of fetal cardiac ventricles during uncomplicated pregnancy.

Materials and Methods

Fetal echocardiography was performed on 160 pregnant women between 14 and 28 weeks' gestation. Measurements were taken on the four‐chamber view. The area of each ventricle was measured by tracing the endocardium at the end of systole and at the end of diastole. Area shortening fraction was calculated by the following formula: SF = (Ad − As)/Ad (SF–area shortening fraction, Ad–end‐diastolic ventricular area, As—end‐systolic ventricular area).

Results

A statistically significant increase in normal fetal area shortening fraction, end‐diastolic area and end‐systolic area of both ventricles with advancing gestational age was established. There were no significant differences in the area shortening fraction between right and left ventricles.

Conclusions

Area shortening fraction shows good correlation with gestational age. Nomogram of area shortening fraction, end‐diastolic area and end‐systolic area of both ventricles can be used as the reference for evaluation of ventricle size and cardiac contractility in normal and pathological cases. Copyright © 2004 John Wiley & Sons, Ltd.
Contingent screening for Down syndrome is an efficient alternative to non‐disclosure sequential screening
Authors: Wright Dave , Bradbury Ian , Benn Peter , Cuckle Howard , Ritchie Karen
Published: November 2004

Objective

To present a first and second trimester Down syndrome screening strategy, whereby second‐trimester marker determination is contingent on the first‐trimester results. Unlike non‐disclosure sequential screening (‘the Integrated test’), which requires all women to have markers in both trimesters, this allows a large proportion of the women to complete screening in the first trimester.

Methods

Two first‐trimester risk cut‐offs defined three types of results: positive and referred for early diagnosis; negative with screening complete; and intermediate, needing second‐trimester markers. Multivariate Gaussian modelling with Monte Carlo simulation was used to estimate the false‐positive rate for a fixed 85% detection rate. The false‐positive rate was evaluated for various early detection rates and early test completion rates. Model parameters were taken from the SURUSS trial.

Results

Completion of screening in the first trimester for 75% of women resulted in a 30% early detection rate and a 55% second trimester detected rate (net 85%) with a false‐positive rate only 0.1% above that achievable by the Integrated test. The screen‐positive rate was 0.1% in the first trimester and 4.7% for those continuing to be tested in the second trimester. If the early detection rate were to be increased to 45% or the early completion rate were to be increased to 80%, there would be a further 0.1% increase in the false‐positive rate.

Conclusion

Contingent screening can achieve results comparable with the Integrated test but with earlier completion of screening for most women. Both strategies need to be evaluated in large‐scale prospective studies particularly in relation to psychological impact and practicability. Copyright © 2004 John Wiley & Sons, Ltd.
Hemodynamic changes with phenotype reversal during pregnancy in twin–twin transfusion syndrome
Authors: Meyberg‐Solomayer G. C. , Fehm T. , Mackensen‐Haen S. , Wallwiener D. , Solomayer E. F.
Published: November 2004

Objectives

We report an atypical case of twin–twin transfusion syndrome (TTTS) in monochorionic‐diamniotic twins with arterio‐arterial anastomoses in which the former donor became the recipient during pregnancy.

Methods

Serial sonographic monitoring was performed.

Results

There was a phenotype reversal in TTTS concerning growth and amniotic fluid ending at 27 weeks, with the dominance of the former smaller donor. Doppler sonography changed from absent enddiastolic flow of the donor to normal values in both twins. The new recipient showed transient ascites, the now smaller actual donor (former recipient) developed progressive cardiomegaly, hypertrophy of the myocardium and mitral and tricuspid insufficiency at 29 weeks. Doppler sonography in the new donor deteriorated to highly pathologic flow in the venous system, leading to cesarean section. The donor fetus died 12 h after delivery because of myocardial decompensation. The recipient did very well and was discharged 8 weeks later from the neonatology unit.

Conclusion

This atypical course shows the importance of serial sonographic monitoring in pregnancies with TTTS. Copyright © 2004 John Wiley & Sons, Ltd.
Performance of front contact silicon solar cells under concentration
Authors: Luque A. , Gidon P. , Pirot M. , Antón I. , Caballero L.J. , Tobías I. , del Cañizo C. , Jausseaud C.
Published: November 2004

The first realization of a new type of silicon solar cell intended for operation at very high concentration, with all the contacts at its front face, is presented. Although the efficiencies achieved are not outstanding, the feasibility of the structure is proven by the fabrication of several thousands of cells with similar performance. Modeling has evidenced the main routes for improvement. Efficiencies close to 25% for a range of efficiencies from 80 to 560 suns are predicted as achievable for cells with state‐of‐the‐art technology and appropriate layout. Copyright © 2004 John Wiley & Sons, Ltd.
“Suprafestes” Helium entdeckt
Authors: Leute Angelika
Published: November 2004

Bei extrem tiefen Temperaturen verlieren manche Flüssigkeiten ihre Viskosität, sie werden suprafluid. Ein solcher völlig reibungsfreier Zustand wurde jetzt erstmals auch bei einem Festkörper experimentell nachgewiesen. Zwei Wissenschaftlern der Pennsylvania State University ist es gelungen, in Kristallen des 4He‐Isotops bei Temperaturen unterhalb von 230 mK ein ungewöhnliches, klassisch nicht erklärbares Rotationsverhalten zu beobachten. Sie deuten ihre Entdeckung als “suprafesten” Zustand.
Käsefondue: eine kolloidale Schmelze
Authors: Vilgis Thomas A.
Published: November 2004

An Weihnachten oder zum Jahreswechsel kommt gern das Fonduegeschirr zum Einsatz, weil sich damit viele hungrige Gäste unterhaltsam sättigen lassen. Käsefondues sind allerdings eine physikalisch anspruchsvolle Angelegenheit. Die Kunst besteht darin, die viskoelastische Käseschmelze während des Genusses homogen zu halten.
Acidic proteome of growing and resting Lactococcus lactis metabolizing maltose
Authors: Palmfeldt Johan , Levander Fredrik , Hahn‐Hägerdal Bärbel , James Peter
Published: November 2004

The acidic proteome of Lactococcus lactis grown anaerobically was compared for three different growth conditions: cells growing on maltose, resting cells metabolizing maltose, and cells growing on glucose. In maltose metabolizing cells several proteins were up‐regulated compared with glucose metabolizing cells, however only some of the up‐regulated proteins had apparent relation to maltose metabolism. Cells growing on maltose produced formate, acetate and ethanol in addition to lactate, whereas resting cells metabolizing maltose and cells growing on glucose produced only lactate. Increased levels of alcohol‐acetaldehyde dehydrogenase (ADH) and phosphate acetyltransferase (PTA) in maltose‐growing cells compared with glucose‐growing cells coincided with formation of mixed acids in maltose‐growing cells. The resting cells did not grow due to lack of an amino acid source and fermented maltose with lactate as the sole product, although ADH and PTA were present at high levels. The maltose consumption rate was approximately three times lower in resting cells than in exponentially growing cells. However, the enzyme levels in resting and growing cells metabolizing maltose were similar, which indicates that the difference in product formation in this case is due to regulation at the enzyme level. The levels of 30S ribosomal proteins S1 and S2 increased with increasing growth rate for resting cells metabolizing maltose, maltose‐growing cells and glucose‐growing cells. A modified form of HPr was synthesized under amino acid starvation. This is suggested to be due to alanine misincorporation for valine, which L. lactis is auxotrophic for. L. lactis conserves the protein profile to a high extent, even after prolonged amino acid starvation, so that the protein expression profile of the bacterium remains almost invariant.
A combination of protein profiling and isotopomer analysis using matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry reveals an active metabolism of the extracellular matrix of 3T3‐L1 adipocytes
Authors: Bouwman Freek , Renes Johan , Mariman Edwin
Published: November 2004

Differential gel electrophoresis followed by matrix‐assisted laser desorption/ionization‐time of flight (MALDI‐TOF) mass spectrometry (MS) is a commonly used protein profiling method. However, observed changes can be explained in multiple ways, one of which is by the protein turnover rate. In order to easily and rapidly obtain information on both the identity and turnover of individual proteins, we applied a combination of protein labeling with L‐(ring‐2,3,4,5,6 2H5) phenylalanine and MALDI‐TOF MS. While the spectrum reveals the identity of a protein, mass isotopomer analysis provides information about the rate of protein labeling as a measure of synthesis or turnover. Using this approach on mature 3T3‐L1 adipocytes, we were able to discriminate between rapidly and slowly metabolised proteins. In our isolate, proteins of the cytoskeleton appeared to be slowly metabolised, whereas components of the extracellular matrix, in particular collagen type I alpha 1 (COL1A1) and collagen type I alpha 2 (COL1A2) showed rapid accumulation of newly synthesized proteins. Both proteins appeared to be metabolised in the same ratio as they are present in collagen fibers, i.e. 2:1 (COL1A1: COL1A2). In addition, functionally related proteins were also readily labeled. Taken together, we have shown that a combination of stable isotope labeling and protein profiling by gel electrophoresis and MALDI‐TOF analysis can simultaneously provide information on the identity and relative metabolic rate of proteins in eukaryotic cells in a simple, nonhazardous and rapid‐throughput way.
Identification of proteins induced by polycyclic aromatic hydrocarbon in Mycobacterium vanbaalenii PYR‐1 using two‐dimensional polyacrylamide gel electrophoresis and de novo sequencing methods
Authors: Kim Seong‐Jae , Jones Richard C. , Cha Chang‐Jun , Kweon Ohgew , Edmondson Ricky D. , Cerniglia Carl E.
Published: November 2004

Protein profiles of Mycobacterium vanbaalenii PYR‐1 grown in the presence of high‐molecular‐weight polycyclic aromatic hydrocarbons (HMW PAHs) were examined by two‐dimensional gel electrophoresis (2‐DE). Cultures of M. vanbaalenii PYR‐1 were incubated with pyrene, pyrene‐4,5‐quinone (PQ), phenanthrene, anthracene, and fluoranthene. Soluble cellular protein fractions were analyzed and compared, using immobilized pH gradient (IPG) strips. More than 1000 gel‐separated proteins were detected using a 2‐DE analysis program within the window of isoelectric point (pI) 4–7 and a molecular mass range of 10–100 kDa. We observed variations in the protein composition showing the upregulation of multiple proteins for the five PAH treatments compared with the uninduced control sample. By N‐terminal sequencing or mass spectrometry, we further analyzed the proteins separated by 2‐DE. Due to the lack of genome sequence information for this species, protein identification provided an analytical challenge. Several PAH‐induced proteins were identified including a catalase‐peroxidase, a putative monooxygenase, a dioxygenase small subunit, a small subunit of naphthalene‐inducible dioxygenase, and aldehyde dehydrogenase. We also identified proteins related to carbohydrate metabolism (enolase, 6‐phosphogluconate dehydrogenase, indole‐3‐glycerol phosphate synthase, and fumarase), DNA translation (probable elongation factor Tsf), heat shock proteins, and energy production (ATP synthase). Many proteins from M. vanbaalenii PYR‐1 showed similarity with protein sequences from M. tuberculosis and M. leprae. Some proteins were detected uniquely upon exposure to a specific PAH whereas others were common to more than one PAH, which indicates that induction triggers not only specific responses but a common response in this strain.
Effects of benzo(a)pyrene on protein expression in Jurkat T‐cells
Authors: Oh Sangnam , Im Hosub , Oh Eunha , Lee Joohyun , Khim Jin‐young , Mun Joohee , Kim Yanghee , Lee Eunil , Kim Joon , Sul Donggeun
Published: November 2004

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants of air, water and soil, and are produced by the incomplete combustion of organic materials. The International Agency for Research on Cancer has characterized PAHs as carcinogens. In this study, we investigated the effects of benzo(a)pyrene (B(a)P), which is the most carcinogenic member of the PAHs, on Jurkat cell protein by proteomic analysis. Jurkat cells were treated with various concentrations of B(a)P (0, 2.5, 5, 10, 20 or 40 μM) for 24 or 48 h and 3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2H‐tetrazolium and lactate dehydrogenase assays were carried out to determine cytotoxicity and a Comet assay was used to determinate genotoxicity. The cytotoxicity assays showed that 2.5 μM of B(a)P was the maximal concentration that did not cause any toxicity, but nevertheless, at this level B(a)P produced significant DNA damage in Jurkat cells at 48 h. Proteomic analysis using three different pI ranges and large two‐dimensional gel electrophoresis showed 3427 protein spots. A total of 46 (13 up‐ and 33 down‐regulated) proteins were identified as biomarkers of B(a)P and showed dose‐dependent expressions in Jurkat T‐cell line exposed to B(a)P. Of these, 27 protein spots were identified by matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry. Two functionally differentiated protein groups were found. The protein group involving apoptosis and tumor suppression were found to be up‐regulated, and B(a)P down‐regulated enzyme was involved in energy metabolism, DNA synthesis and in cell structure and motility.