bluuebunny/crossref_metadata_2025 huggingface dataset:
Two‐point water‐fat imaging with partially‐opposed‐phase (POP) acquisition: An asymmetric Dixon method
Authors: Xiang Qing‐San
Published: August 2006

A novel two‐point water‐fat imaging method is introduced. In addition to the in‐phase acquisition, water and fat magnetization vectors are sampled at partially‐opposed‐phase (POP) rather than exactly antiparallel as in the original Dixon method. This asymmetric sampling encodes more valuable phase information for identifying water and fat. From the magnitudes of the two complex images, a big and a small chemical component are first robustly obtained pixel by pixel and then used to form two possible error phasor candidates. The true error phasor is extracted from the two error phasor candidates through a simple procedure of regional iterative phasor extraction (RIPE). Finally, least‐squares solutions of water and fat are obtained after the extracted error phasor is smoothed and removed from the complex images. For noise behavior, the effective number of signal averages NSA* is typically in the range of 1.87–1.96, very close to the maximum possible value of 2. Compared to earlier approaches, the proposed method is more efficient in data acquisition and straightforward in processing, and the final results are more robust. At both 1.5T and 0.3T, well separated and identified in vivo water and fat images covering a broad range of anatomical regions have been obtained, supporting the clinical utility of the method. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Delayed changes in T1‐weighted signal intensity in a rat model of 15‐minute transient focal ischemia studied by magnetic resonance imaging/spectroscopy and synchrotron radiation X‐ray fluorescence
Authors: Wang Xuxia , Qian Junchao , He Rui , Wei Li , Liu Nianqing , Zhang Zhiyong , Huang Yuying , Lei Hao
Published: August 2006

Previous studies have found that rats subjected to 15‐min transient middle cerebral artery occlusion (MCAO) show neurodegeneration in the dorsolateral striatum only, and the resulting striatal lesion is associated with increased T1‐weighted (T1W) signal intensity (SI) and decreased T2‐weighted (T2W) SI at 2–8 weeks after the initial ischemia. It has been shown that the delayed increase in T1W SI in the ischemic region is associated with deposition of paramagnetic manganese ions. However, it has been suggested that other mechanisms, such as tissue calcification and lipid accumulation, also contribute to the relaxation time changes. To clarify this issue, we measured changes in relaxation times, lipid accumulation, and elemental distributions in the brain of rats subjected to 15‐min MCAO using MRI, in vivo 1H MR spectroscopy (MRS), and synchrotron radiation X‐ray fluorescence (SRXRF). The results show that a delayed (2 weeks after ischemia) increase in T1W SI in the ischemic striatum is associated with significant increases in manganese, calcium, and iron, but without evident accumulation of MRS‐visible lipids or hydroxyapatite precipitation. It was also found that 15‐min MCAO results in acutely reduced N‐acetylaspartate (NAA)/creatine (Cr) ratio in the ipsilateral striatum, which recovers to the control level at 2 weeks after ischemia. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
SENSE optimization of a transceive surface coil array for MRI at 4 T
Authors: Pinkerton Robert G. , McKinnon Graeme C. , Menon Ravi S.
Published: August 2006

Parallel imaging (PI) techniques employ the use of multiple radiofrequency (RF) channels to transmit and/or receive the NMR signal. In the current study we use a finite difference time domain (FDTD) method to simulate the electromagnetic fields of a RF coil array operating in transmit‐receive (transceive) mode and receive‐only mode. Optimization of these configurations for PI is studied as well. Our results suggest that a coil array can effectively be used for transceive or receive‐only PI techniques. For a head coil configuration, the sensitivity encoding (SENSE) optimized coil array gap size and PI acceleration factor for MRI are shown to be a function of the physiological‐to‐intrinsic‐noise ratio (PhINR) with a much stronger dependence on acceleration factor than gap size. The results provide a means to optimize any PI sequence by varying the acceleration factor based on the measured PhINR. In addition, an example design for an eight‐element transceive coil array for heads at 4 T is given. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Efficient visualization of vascular territories in the human brain by cycled arterial spin labeling MRI
Authors: Günther Matthias
Published: August 2006

Intracranial vascular territories are usually visualized with the use of angiographic techniques. However, because it is difficult to visualize the distal vascular bed with any angiographic technique, it is also difficult to infer the parenchymal borders of vascular territories. Arterial spin labeling (ASL) MRI provides information on cerebral perfusion, and a regional ASL (regASL) approach offers the potential to visualize perfusion of the anterior and posterior circulation separately. Current techniques perform the labeling in each feeding artery as a separate experiment, which is very time‐consuming. In this work a very time‐efficient regASL technique is presented that acquires all vascular territories within the same experiment. Images with different combinations of labeled arteries are combined to delineate the vascular territory of interest. Five subjects were examined with a clinical 1.5T MR scanner. A sharp delineation of the middle cerebral artery (MCA) and posterior cerebral artery (PCA) territories with whole‐brain coverage was achieved in all subjects. The resulting signal‐to‐noise ratios (SNRs) for conventional regASL and the proposed cycled regASL were 9.3 ± 2.4 and 15.3 ± 5.1, respectively. An optimized setup was achieved by combining the regional labeling scheme with an efficient readout technique, which yielded a total measurement time of 2 min for three vascular territories. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
An Eulerian‐Lagrangian method for option pricing in finance
Authors: Wang Zheng , Al‐Lawatia Mohamed , Wang Hong
Published: August 2006

This article is devoted to the development and application of an Eulerian‐Lagrangian method (ELM) for the solution of the Black‐Scholes partial differential equation for the valuation of European option contracts. This method fully utilizes the transient behavior of the governing equations and generates very accurate option's fair values and their derivatives also known as option Greeks, even if coarse spatial grids and large time steps are used. Numerical experiments on two standard option contracts are presented which show that the ELM method (favorably) compares in terms of accuracy and efficiency to many other well‐perceived methods. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 293–329, 2007
Proteomic analysis of the autoantibody response following immunization with a single autoantigen
Authors: Mouquet Hugo , Drouot Laurent , Charlionnet Roland , Arnoult Christophe , Bonnet‐Bayeux Florence , Thomas Marlène , Leprince Jérôme , Joly Pascal , Tron François , Gilbert Danièle
Published: August 2006

In most autoimmune diseases, the autoantibody response is directed against several antigens of the target organ whose identification is crucial for understanding the physiopathological process. Thus, technologies allowing a characterization of the whole autoantibody pattern of both human and experimental autoimmune diseases are required. Here we have used immunoproteomic analysis of human epidermal extracts to characterize the diversity of the anti‐desmosome antibody response induced in normal mice immunized with desmoglein 1, the major autoantigen of pemphigus foliaceus, an autoimmune blistering skin disease. In particular, this analysis enables us to characterize the binding properties of anti‐desmosome mAbs derived from these mice and to show that the autoantibody response induced upon immunization with a single autoantigen targets different epidermal autoantigens with a pattern similar to that observed in certain variety of human pemphigus.
Preparation and characterization of chitosan‐graft‐poly (ϵ‐caprolactone) with an organic catalyst
Authors: Feng Hao , Dong Chang‐Ming
Published: August 2006

Chitosan‐graft‐poly(ϵ‐caprolactone) was prepared via the ring‐opening graft polymerization of ϵ‐caprolactone (CL) through chitosan with 4‐dimethylaminopyridine as a catalyst and water as a swelling agent. The graft content of PCL within the graft copolymer was adjusted by the feed ratio of CL to chitosan, and the highest grafting concentration of PCL was up to about 400%. Fourier transform infrared, 1H NMR, and two‐dimensional heteronuclear single quantum coherence analyses indicated that the amino group (NH2CH‐2) of chitosan initiated the graft polymerization of CL through the backbone of chitosan, and the hydroxyl group (HOCH2–6) of chitosan did not participate in initiating the graft polymerization. The percentage of amino groups initiating the graft polymerization decreased with an increasing molar ratio of CL to chitosan in the feed, and this was attributed to the fact that the graft polymerization system increasingly became heterogeneous with an increasing feed ratio of CL to chitosan. The physical properties of the graft copolymers were characterized by thermogravimetric analysis and wide‐angle X‐ray diffraction, respectively. These suggested that the introduction of PCL grafts through the chitosan backbone would to some extent destroy the crystalline structure of chitosan, and the PCL grafts existed in an amorphous structure. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5353–5361, 2006
Elaboration of well‐defined Rasta resins and their use as supported catalytic systems for atom transfer radical polymerization
Authors: Fournier David , Pascual Sagrario , Montembault Véronique , Fontaine Laurent
Published: August 2006

New supported catalytic systems based on the immobilization of a ligand onto supported (co)polymers were prepared, allowing copper immobilization onto a solid support during the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). These supported catalysts were elaborated by the ATRP of 2‐vinyl‐4,4‐dimethyl‐5‐oxazolone and/or styrene onto a Wang resin initiator. Two different approaches were used, involving well‐defined architectures synthesized by ATRP. First, a supported electrophilic homopolymer [Wang‐g‐poly(2‐vinyl‐4,4‐dimethyl‐5‐oxazolone)] was synthesized to obtain an azlactone ring at each repetitive unit, and a supported statistical copolymer [Wang‐g‐poly(2‐vinyl‐4,4‐dimethyl‐5‐oxazolone‐stat‐styrene)] was synthesized to introduce a distance between the azlactone rings. The azlactone‐based (co)polymers were then modified by a reaction with N,N,N′,N′‐tetraethyldiethylenetriamine (TEDETA) to create supported complexing sites for copper bromide. The ATRP of MMA was studied with these supported ligands, and a first‐order kinetic plot was obtained, but high polydispersity indices of the obtained poly(methyl methacrylate) were observed (polydispersity index > 2). On the other hand, the supported ATRP of styrene was performed, followed by the nucleophilic substitution of bromine by TEDETA (Wang‐g‐polystyrene–N,N,N′,N′‐tetraethyldiethylenetriamine) at the chain end of the grafted polystyrene chains. This strategy led the ligand away from the core bead, depending on the length of the polystyrene block (number‐average molecular weight determined by size exclusion chromatography = 1100–2250 g/mol). These supported complexes mediated a controlled polymerization of MMA, yielding polymers with controlled molar masses and low polydispersity indices. Moreover, after the polymerization, 96% of the initial copper was kept in the beads. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5316–5328, 2006
Multiscale dynamics of an interacting sheet by a bond‐fluctuating Monte Carlo simulation
Authors: Pandey R. B. , Anderson Kelly L. , Farmer B. L.
Published: August 2006

The conformation and dynamics of sheets with attractive and repulsive node–node interactions (nn) are examined in an effective solvent medium using Monte Carlo simulations. A bond‐fluctuating coarse grained description is used to model the sheet by a set of nodes (N) tethered together by flexible bonds in a planar structure with linear scaleLs= 16–64,N=Lon a cubic lattice with characteristic dimensions ofL3= 643–2003. Variations of the mean square displacement of the center of mass of the sheet (R) and that of its center node (R) and radius of gyration (Rg) of the sheet with the time step (t) are analyzed to characterize the nature of its global motion, segmental dynamics, and conformational relaxation at a low (T= 2) and a high (T= 10) temperature with the range (r= √8) of interactionnn= 1, –1. We find that sheets achieve their global diffusive motion, that is,R∝t, in the long‐time (asymptotic) regime while their segmental dynamics exhibits a range of power‐law behaviorR∝tνwith ν = 1/4−1 from short to long‐time regimes. The magnitude of the exponent ν and their crossover (and relaxation) from one power‐law to the next depend on temperature, interaction, and molecular weightNof the sheet. The radius of gyration of the sheet relaxes well to its equilibrium with its distinct patterns of expansion (swelling with relatively stiffer bonds (nn= 1)) and contraction (crumpling withnn= −1). Both the relaxation time and the rate of change ofRgdepends onN, Ls, andT. Data for the equilibrium value of the gyration radius scale with its sizeRg∝N1/2suggesting that sheets remain nearly flat with localized wrinkles and crumpling.© 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2512–2523, 2006
Exploring the relationship between funneled energy landscapes and two‐state protein folding
Authors: Konermann Lars
Published: August 2006

It should take an astronomical time span for unfolded protein chains to find their native state based on an unguided conformational random search. The experimental observation that folding is fast can be rationalized by assuming that protein energy landscapes are sloped towards the native state minimum, such that rapid folding can proceed from virtually any point in conformational space. Folding transitions often exhibit two‐state behavior, involving extensively disordered and highly structured conformers as the only two observable kinetic species. This study employs a simple Brownian dynamics model of “protein particles” moving in a spherically symmetrical potential. As expected, the presence of an overall slope towards the native state minimum is an effective means to speed up folding. However, the two‐state nature of the transition is eradicated if a significant energetic bias extends too far into the non‐native conformational space. The breakdown of two‐state cooperativity under these conditions is caused by a continuous conformational drift of the unfolded proteins. Ideal two‐state behavior can only be maintained on surfaces exhibiting large regions that are energetically flat, a result that is supported by other recent data in the literature (Kaya and Chan, Proteins: Struct Funct Genet 2003;52:510–523). Rapid two‐state folding requires energy landscapes exhibiting the following features: (i) A large region in conformational space that is energetically flat, thus allowing for a significant degree of random sampling, such that unfolded proteins can retain a random coil structure; (ii) a trapping area that is strongly sloped towards the native state minimum. Proteins 2006. © 2006 Wiley‐Liss, Inc.
A substitution matrix for structural alphabet based on structural alignment of homologous proteins and its applications
Authors: Tyagi Manoj , Gowri Venkataraman S. , Srinivasan Narayanaswamy , de Brevern Alexandre G. , Offmann Bernard
Published: August 2006

Analysis of protein structures based on backbone structural patterns known as structural alphabets have been shown to be very useful. Among them, a set of 16 pentapeptide structural motifs known as protein blocks (PBs) has been identified and upon which backbone model of most protein structures can be built. PBs allows simplification of 3D space onto 1D space in the form of sequence of PBs. Here, for the first time, substitution probabilities of PBs in a large number of aligned homologous protein structures have been studied and are expressed as a simplified 16 × 16 substitution matrix. The matrix was validated by benchmarking how well it can align sequences of PBs rather like amino acid alignment to identify structurally equivalent regions in closely or distantly related proteins using dynamic programming approach. The alignment results obtained are very comparable to well established structure comparison methods like DALI and STAMP. Other interesting applications of the matrix have been investigated. We first show that, in variable regions between two superimposed homologous proteins, one can distinguish between local conformational differences and rigid‐body displacement of a conserved motif by comparing the PBs and their substitution scores. Second, we demonstrate, with the example of aspartic proteinases, that PBs can be efficiently used to detect the lobe/domain flexibility in the multidomain proteins. Lastly, using protein kinase as an example, we identify regions of conformational variations and rigid body movements in the enzyme as it is changed to the active state from an inactive state. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Effects of lambda‐cyhalothrin on mosquito larvae and predatory aquatic insects
Authors: Lawler Sharon P , Dritz Deborah A , Christiansen Julie A , Cornel Anthony J
Published: August 2006

Agricultural insecticides can affect mosquito production in rice fields by controlling mosquitoes, disrupting biological control or contributing to selection of insecticide resistance. The duration of insecticidal activity of the pyrethroid lambda‐cyhalothrin was quantified on predatory insects in rice fields and on three kinds of mosquito larva: a pyrethroid‐susceptible strain of Culex tarsalis Coquillet, a pyrethroid‐resistant strain of Cx pipiens L. (sensu lato) and non‐resistant Cx pipiens s.l. Lambda‐cyhalothrin killed most caged, susceptible mosquitoes for up to 21 days. It killed fewer resistant Cx pipiens s.l., but suppressed their survival for over a week. Lambda‐cyhalothrin suppressed field populations of predatory insects through day 29. Agricultural use of lambda‐cyhalothrin can provide incidental mosquito control. However, the pyrethroid persisted in sediment and gradually decreased in activity, which could contribute to selection of pyrethroid‐resistant mosquitoes. Because caged mosquitoes showed good survival before predators recovered, disruption of biological control is possible. It is therefore advisable for growers and mosquito control agencies to communicate about pesticide use. Copyright © 2006 Society of Chemical Industry
Electrical conductivity of prelocalized graphite‐filled blend of polyvinyl chloride/styrene acrylonitrile composites in relationship to morphology and hardness
Authors: Sachdev V. K. , Srivastava N. K. , Panwar Varij , Singh H. , Mehra N. C. , Mehra R. M.
Published: August 2006

At present there is a greater need to design conducting polymeric composites that suit particular application with little compromise on mechanical properties. This work deals with the study of electrical conductivity and mechanical strength of graphite‐filled blend of polyvinyl chloride/styrene acrylonitrile (PVC/SAN) composites. Samples were prepared by prelocalization of graphite onto the particles of PVC and SAN with subsequent compression molding. At a fixed volume ratio of 1:1 of PVC/SAN, percolation threshold of 0.0063 volume fraction of graphite has been observed. SAN has improved the D‐shore hardness of composites. Composites with more than 3 wt% graphite content have good conductivity and still preserve a reasonable mechanical strength. Conductivity patterns suggest higher affinity of graphite for PVC as compared to SAN. Scanning electron microscopy (SEM) micrographs indicate the widening of graphite layers with increasing graphite content. The electrical conductivity of composites has been explained in terms of percolation theory. The universal exponent t is found to be 3.09 for a best‐fit value of percolation threshold of 0.0057 volume fraction of graphite. There is good agreement between calculated and experimental values. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective Hamiltonian for potassium dynamics in the β ‐pyrochlore superconductor KOs2O6
Authors: Kuneš J. , Pickett W. E.
Published: August 2006

Based on ab initio energies and forces we construct an effective Hamiltonian for anharmonic dynamics of potassium cations in the β ‐pyrochlore compound KOs2O6. We solve numerically the single‐site problem which is characterized by an extremely flat potential well allowing for large excursions of K‐ions, and illustrate graphically the K‐ion wavefunctions in the four off‐center (symmetry‐breaking) sites. These large displacements from the ideal lattice site result in sizable K–K near‐neighbor interactions through a screened Coulomb interaction. The matrix elements of the interaction in the basis of single‐site eigenstates are calculated and discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Epitaxial vapor–liquid–solid growth of silicon nano‐whiskers by electron beam evaporation
Authors: Sivakov V. , Andrä G. , Gösele U. , Christiansen S.
Published: August 2006

Epitaxial silicon nanowhiskers (NWs) were grown on Si(111) substrates by electron beam evaporation (EBE) in a non‐ultra high vacuum environment (base pressure 1–2 × 10–7 Torr). Comparably low growth temperatures between 575 and 675 °C were realized making use of the gold driven 1D growth by the vapor‐liquid‐solid (VLS) growth mechanism. Diameters and lengths of the NWs were observed in the ranges between 50 and 200 nm and 200 and 670 nm, respectively. A maximum NW growth velocity of 5 nm/min was realized for the evaporation current of 35 mA. This value determines particle flux and thus growth velocity and is at the lower end of evaporation currents studied so far. But a value that yields a growth velocity comparable to the one realized by the more intensively studied ultra‐high vacuum molecular beam epitaxy (MBE) method. The EBE NW morphology, defect structure and the interface between NWs and substrate are characterized by scanning and transmission electron microscopy (SEM, TEM) techniques. The NW material from EBE is compared to NWs grown by MBE and similarities and differences are pointed out. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new Li2O–Nb2O5–TiO2 microwave dielectric ceramic composite
Authors: Zeng Qun , Li Wei , Shi Jian‐lin , Guo Jing‐kun
Published: August 2006

In the Li2O–Nb2O5–TiO2 (LNT) system, a new dielectric ceramic composite with special structure has been found and investigated. The compound is composed of two phases, the “M‐phase” and Li2TiO3 solid solution phase. This ceramic composite has a low sintering temperature (∼1100 °C) and good microwave dielectric properties of high permittivity (∼49), high Q × f value up to 9500 GHz, and small tempe‐ rature coefficient (∼22 ppm/°C). Furthermore, by adding 1 wt% B2O3, the ceramic could be densified at very low sintering temperatures (≯900 °C) and also have good microwave dielectric properties of ϵ r = 49.2, Q × f = 8839 GHz, which suggests that the ceramic could be a promising candidate for multilayer low‐temperature co‐fired ceramics applications. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A sequential procedure for monitoring clinical trials against historical controls
Authors: Xiong Xiaoping , Tan Ming , Boyett James
Published: August 2006

In this paper, we develop a sequential procedure to monitor clinical trials against historical controls. When there is a strong ethical concern about randomizing patients to existing treatment because biological and medical evidence suggests that the new treatment is potentially superior to the existing one, or when the enrollment is too limited for randomization of subjects into experimental and control groups, one can monitor the trial sequentially against historical controls if the historical data with required quality and sample size are available to form a valid reference for the trial. This design of trial is sometimes the only alternative to a randomized phase III trial design that is intended but not feasible in situations such as above. Monitoring this type of clinical trial leads to a statistical problem of comparing two population means in a situation in which data from one population are sequentially collected and compared with all data from the other population at each interim look. The proposed sequential procedures is based on the sequential conditional probability ratio test (SCPRT) by which the conclusion of the sequential test would be virtually the same as that arrived at by a non‐sequential test based on all data at the planned end of the trial. We develop the sequential procedure by proposing a Brownian motion that emulates the test statistic, and then proposing an SCPRT that is adapted to the special properties of the trial. Copyright © 2006 John Wiley & Sons, Ltd.
Instrumental variables and interactions in the causal analysis of a complex clinical trial
Authors: Bond Simon J. , White Ian R. , Sarah Walker A.
Published: August 2006

We consider the application of instrumental variable techniques in a longitudinal clinical trial in paediatric HIV/AIDS, with a substantial degree of non‐compliance to randomized treatment (Nelfinavirversusplacebo) and with left censoring of the outcome variable (HIV RNA concentration). We consider in detail the assumptions and implications behind the inclusion and exclusion of interactions between randomized arm and baseline covariates in modelling actual treatment received, and between treatment and baseline covariates in modelling outcome. Estimated treatment effects were sensitive to inclusion of interactions, and we show how such sensitivity can be explored and explained. Copyright © 2006 John Wiley & Sons, Ltd.
Performance of adaptive sample size adjustment with respect to stopping criteria and time of interim analysis
Authors: Jahn‐Eimermacher Antje , Hommel Gerhard
Published: August 2006

The benefit of adjusting the sample size in clinical trials on the basis of treatment effects observed in interim analysis has been the subject of several recent papers. Different conclusions were drawn about the usefulness of this approach for gaining power or saving sample size, because of differences in trial design and setting. We examined the benefit of sample size adjustment in relation to trial design parameters such as ‘time of interim analysis’ and ‘choice of stopping criteria’. We compared the adaptive weighted inverse normal method with classical group sequential methods for the most common and for optimal stopping criteria in early, half‐time and late interim analyses. We found that reacting to interim data might significantly reduce average sample size in some situations, while classical approaches can out‐perform the adaptive designs under other circumstances. We characterized these situations with respect to time of interim analysis and choice of stopping criteria. Copyright © 2006 John Wiley & Sons, Ltd.
An overall strategy based on regression models to estimate relative survival and model the effects of prognostic factors in cancer survival studies
Authors: Remontet L. , Bossard N. , Belot A. , Estève J. ,   the French network of cancer registries FRANCIM
Published: August 2006

Relative survival provides a measure of the proportion of patients dying from the disease under study without requiring the knowledge of the cause of death. We propose an overall strategy based on regression models to estimate the relative survival and model the effects of potential prognostic factors. The baseline hazard was modelled until 10 years follow‐up using parametric continuous functions. Six models including cubic regression splines were considered and the Akaike Information Criterion was used to select the final model. This approach yielded smooth and reliable estimates of mortality hazard and allowed us to deal with sparse data taking into account all the available information. Splines were also used to model simultaneously non‐linear effects of continuous covariates and time‐dependent hazard ratios. This led to a graphical representation of the hazard ratio that can be useful for clinical interpretation. Estimates of these models were obtained by likelihood maximization. We showed that these estimates could be also obtained using standard algorithms for Poisson regression. Copyright © 2006 John Wiley & Sons, Ltd.
New Sizing Agents and Flocculants Derived From Chitosan
Authors: Hebeish Ali , Higazy Asha , El‐Shafei Amira
Published: August 2006

Approaches for development of novel textile sizing agents and flocculants based on acid‐hydrolyzed and carboxymethylated chitosans were undertaken. Factors affecting both hydrolysis and carboxymethylation were investigated. Aqueous solutions of hydrolyzed chitosans or carboxymethyl chitosans were applied to light cotton to test the feasibility of such water‐soluble chitosans for textile sizing. The size add‐on on the light fabric is directly related to the concentration of the hydrolyzed or carboxymethyl chitosan in the sizing solution and so does the apparent viscosity of the latter. Hundred percent size removal could be achieved with the hydrolyzed chitosans. A different situation was encountered with carboxymethyl chitosan where the percent size removal increases from 81% to 95% by increasing its concentration in the sizing solution from 5% to 15%. The tensile strength of the sized fabrics increased by about 55% and the elongation at break decreased on average by about 3%. The suitability of the hydrolyzed chitosans and carboxymethyl chitosans as flocculants was also investigated. The degree of flocculation was followed at different pHs by determination of the transmission%. Efficiency of flocculation at pH 6 was greater than at pH 8.
Search‐based software test data generation for string data using program‐specific search operators
Authors: Alshraideh Mohammad , Bottaci Leonardo
Published: August 2006

This paper presents a novel approach to automatic software test data generation, where the test data is intended to cover program branches which depend on string predicates such as string equality, string ordering and regular expression matching. A search‐based approach is assumed and some potential search operators and corresponding evaluation functions are assembled. Their performance is assessed empirically by using them to generate test data for a number of test programs. A novel approach of using search operators based on programming language string operators and parameterized by string literals from the program under test is introduced. These operators are also assessed empirically in generating test data for the test programs and are shown to provide a significant increase in performance. Copyright © 2006 John Wiley & Sons, Ltd.
A 7‐year Experience with Thoracoscopic Sympathectomy for Critical Upper Limb Ischemia
Authors: Lee Arvind Dhas , Agarwal Sunil , Sadhu David
Published: August 2006

Background

Severely symptomatic arterial insufficiency of an upper limb not suitable for revascularization is a difficult condition to manage. Thoracoscopic sympathectomy (TS) can be an effective procedure in this setting.

Methods

Our experience with 18 consecutive thoracoscopic sympathectomy (TS) procedures over a period of 7 years has been reviewed. Indications, operative technique, complications, and outcome of surgery are analyzed.

Results

We performed 18 TS procedures on 17 patients during this period. There were no deaths. One patient had intraoperative hemorrhage necessitating conversion to open thoracotomy. Mean postoperative hospital stay was 2.3 days. Follow‐up ranged from 6 to 72 months. All patients demonstrated clinical benefit from the procedure.

Conclusions

Thoracoscopic sympathectomy is a useful option in patients with severely symptomatic hand and digital ischemia from occlusive small arterial disease like thromboangitis obliterans.
Diagnosis and Treatment of Gastric Heterotopic Pancreas
Authors: Ormarsson Orri Thor , Gudmundsdottir Ingibjorg , Mårvik Ronald
Published: August 2006

Background

Heterotopic pancreas (HP) in the stomach can be difficult to diagnose and there are many treatment options. The aim of this article is to review the contemporary diagnosis of and treatment options for HP in the stomach.

Methods

We undertook a retrospective review of patients with the diagnosis heterotopic pancreas registered at St. Olavs University Hospital in Trondheim from 1990 to 2002. We report on clinical findings, provide a histological review, and summarize the literature with particular emphasis on the diagnosis and treatment of HP in the stomach.

Results

We found 32 cases, most of them in the stomach and the small intestine. Sixteen patients were symptomatic. A histological examination showed that most of the tumors were submucosal and had the appearance of normal pancreas tissue.

Conclusion

Gastric HP is not an uncommon diagnosis compared with many other gastric tumors and should more often be considered as a differential diagnosis. Symptom correlation is not always easy to determine, but symptom relief after treatment is well established. An endoscopic ultrasound examination may help when screening patients for extended biopsy and in deciding on which type of operation is to be performed. When treated, minimally invasive techniques should be applied.
Electronic structures of GaAs/Al
x
Ga1-x
As quantum double rings
Authors: Li Shu-Shen , Xia Jian-Bai
Published: August 2006

In the framework of effective mass envelope function theory, the electronic structures of GaAs/Al
x
Ga1-x
As quantum double rings (QDRs) are studied. Our model can be used to calculate the electronic structures of quantum wells, wires, dots, and the single ring. In calculations, the effects due to the different effective masses of electrons and holes in GaAs and Al
x
Ga1-x
As and the valence band mixing are considered. The energy levels of electrons and holes are calculated for different shapes of QDRs. The calculated results are useful in designing and fabricating the interrelated photoelectric devices. The single electron states presented here are useful for the study of the electron correlations and the effects of magnetic fields in QDRs.
Cardiomyocyte apoptosis is related to left ventricular dysfunction and remodelling in dilated cardiomyopathy, but is not affected by growth hormone treatment
Authors: Ibe Waltraut , Saraste Antti , Lindemann Stephan , Bruder Stephanie , Buerke Michael , Darius Harald , Pulkki Kari , Voipio‐Pulkki Liisa‐Maria
Published: August 2006

Background and aims

Cardiomyocyte apoptosis (CA) is a common feature of end‐stage heart failure. We examined whether CA is associated with cardiac dysfunction and remodelling in heart failure due to dilated cardiomyopathy and studied the effect of human growth hormone (hGH) on CA.

Methods and results

We studied 38 patients, included in a phase III multi‐center, randomised, double‐blind and placebo‐controlled trial of biosynthetic hGH treatment in dilated cardiomyopathy, at baseline and after 14 weeks treatment. Twenty‐six patients received hGH and 12 received placebo. CA was quantified in endomyocardial biopsies using the TUNEL assay. CA correlated with left ventricular size (r=0.43, p=0.007). Compared to patients with CA below the median of 0.53%, patients with CA above the median had significantly larger left ventricular volumes and lower ejection fractions (EF) by echocardiography (median (interquartile range)) 200 ml (84) vs. 257 ml (134) and 27% (11) vs. 23% (9). Expression of the Fas receptor was associated with a high rate of CA. hGH treatment significantly increased serum IGF‐1 levels, but it had no effect on CA or cardiac structure and function.

Conclusion

CA is related to left ventricular enlargement and dysfunction in dilated cardiomyopathy. CA is not affected by short‐term treatment with hGH.
Effect of hypnotic suggestion on fibromyalgic pain: Comparison between hypnosis and relaxation
Authors: Castel Antoni , Pérez Magdalena , Sala José , Padrol Anna , Rull Maria
Published: August 2006

The main aims of this experimental study are: (1) to compare the relative effects of analgesia suggestions and relaxation suggestions on clinical pain, and (2) to compare the relative effect of relaxation suggestions when they are presented as “hypnosis” and as “relaxation training”. Forty‐five patients with fibromyalgia were randomly assigned to one of the following experimental conditions: (a) hypnosis with relaxation suggestions; (b) hypnosis with analgesia suggestions; (c) relaxation. Before and after the experimental session, the pain intensity was measured using a visual analogue scale (VAS) and the sensory and affective dimensions were measured with the McGill Pain Questionnaire. The results showed: (1) that hypnosis followed by analgesia suggestions has a greater effect on the intensity of pain and on the sensory dimension of pain than hypnosis followed by relaxation suggestions; (2) that the effect of hypnosis followed by relaxation suggestions is not greater than relaxation. We discuss the implications of the study on our understanding of the importance of suggestions used in hypnosis and of the differences and similarities between hypnotic relaxation and relaxation training.
Identification of the HIV‐1 gp41 core‐binding motif – HXXNPF
Authors: Huang Jing-He , Liu Zu-Qiang , Liu Shuwen , Jiang Shibo , Chen Ying-Hua
Published: August 2006

The HIV‐1 gp41 core, a six‐helix bundle formed between the N‐ and C‐terminal heptad repeats, plays a critical role in fusion between the viral and target cell membranes. Using N36(L8)C34 as a model of the gp41 core to screen phage display peptide libraries, we identified a common motif, HXXNPF (X is any of the 20 natural amino acid residues). A selected positive phage clone L7.8 specifically bound to N36(L8)C34 and this binding could be blocked by a gp41 core‐specific monoclonal antibody (NC‐1). JCH‐4, a peptide containing HXXNPF motif, effectively inhibited HIV‐1 envelope glycoprotein‐mediated syncytium‐formation. The epitope of JCH‐4 was proven to be linear and might locate in the NHR regions of the gp41 core. These data suggest that HXXNPF motif may be a gp41 core‐binding sequence and HXXNPF motif‐containing molecules can be used as probes for studying the role of the HIV‐1 gp41 core in membrane fusion process.
P‐glycoprotein effect on the properties of its natural lipid environment probed by Raman spectroscopy and Langmuir–Blodgett technique
Authors: Oleinikov Vladimir A. , Fleury Fabrice , Ianoul Anatoli , Zaitsev Sergey , Nabiev Igor
Published: August 2006

Behavior of P‐glycoprotein (Pgp) natural lipid environment within the membrane of CEM cells expressing Pgp in the quantities varying from 0% to 32% of the total amount of all membrane proteins is described for the first time. Observed cooperative effect of Pgp‐induced increase of membrane stability, decrease of the temperature of gel‐to‐crystal lipids transition and predominance of the lipid liquid crystalline phase at physiological temperatures should have an impact in development of multidrug resistance phenotype of tumor cells by favoring the Pgp intercellular transfer and Pgp ATPase activity.
Possible role of avian uncoupling protein in down‐regulating mitochondrial superoxide production in skeletal muscle of fasted chickens
Authors: Abe Tomoki , Mujahid Ahmad , Sato Kan , Akiba Yukio , Toyomizu Masaaki
Published: August 2006

Little is known about the precise physiological roles of uncoupling protein 1 (UCP1) homologs (UCP2, UCP3, avian UCP) whose levels are up‐regulated during fasting. UCPs in skeletal muscle are thought to play a role in the regulation of lipids as fuel substrates, and/or in controlling the production of reactive oxygen species (ROS). The aim of this investigation, using skeletal muscle from fasted chickens, was to examine alterations in the expression of genes encoding for avian UCP and key enzymes relevant to lipid flux across the mitochondrial β‐oxidation pathway. We also clarified whether an increase in avUCP content could be associated with altered ROS production by mitochondria. Transcription levels of avUCP and CPT‐I genes were increased 7.7‐ and 9.5‐fold after a 24 h fast and slightly diminished but remained about 5.0‐ and 7.7‐fold higher than baseline levels, respectively, after 48 h of fasting. In contrast, members of the β‐oxidation pathway, LCAD and 3HADH, were gradually up‐regulated from 12 to 48 h of fasting. This suggests that processes involved in the transfer and oxidation of fatty acids are up‐regulated differently during the initial stage of fasting. Analysis of ROS production by lucigenin‐derived chemiluminescence showed that the FFA‐sensitive portion of carboxyatractyloside‐upregulated ROS production was greater in skeletal muscle mitochondria from 24 h‐fasted chickens compared with control, which leads us to postulate that ROS production is potentially down‐regulated by UCP. The possible involvement of a backlog of fatty acid for oxidation, observed in chickens after a 24 h fast, in a transmembrane gradient of free non‐oxidized fatty acids is also discussed.
Nitric oxide reacts with the ferryl‐oxo catalytic intermediate of the CuB‐lacking cytochrome bd terminal oxidase
Authors: Borisov Vitaliy B. , Forte Elena , Sarti Paolo , Brunori Maurizio , Konstantinov Alexander A. , Giuffrè Alessandro
Published: August 2006

Cytochrome bd is a bacterial respiratory oxidase carrying three hemes but no copper. We show that nitric oxide (NO) reacts with the intermediate F of cytochrome bd from Azotobacter vinelandii: (i) with a 1:1 stoichiometry, (ii) rapidly (k
= 1.2 ± 0.1 × 105
M−1
s−1 at 20 °C), and (iii) yielding the oxidized enzyme with nitrite bound to heme d at the active site. Unexpectedly, the NO reaction mechanism of this catalytic intermediate in the CuB‐lacking cytochrome bd appears similar to that of beef heart cytochrome c oxidase, where CuB was proposed to play a key role.
Tracheobronchial foreign body aspiration: A continuing challenge
Authors: Soysal Omer , Kuzucu Akin , Ulutas Hakki
Published: August 2006

Objective

The aim was to present the features and outcomes for 140 cases of foreign body aspiration and to discuss specific problems and new management recommendations.

Study Design and Setting

Records were retrospectively reviewed and the following data were recorded for each patient: age, sex, symptoms, duration of symptoms, findings on physical examination and chest radiography, location and type of foreign body, complications related to aspiration itself or to extraction, and outcome.

Results

Seventy‐eight patients presented within 24 hours of aspiration. The most common symptoms and findings were cough, dyspnea‐stridor, decreased breath sounds, radiopaque foreign body, air trapping, and atelectasis. All 140 patients underwent rigid bronchoscopy, and 110 had the foreign material extracted via the scope. No foreign body was detected bronchoscopically in 25 cases. In the other 5 cases, the material was visualized but could not be removed via the scope, and 3 of these patients required thoracotomy for removal. Eleven patients developed morbidity after bronchoscopy.

Conclusion

History suggestive of foreign body aspiration is a definite indication for bronchoscopy, and bronchoscopic extraction should only be performed by experts. Each case tends to present different challenges, and endotracheal intubation and tracheotomy may be required.
Acoustic parameters of snoring sound to assess the effectiveness of sleep nasendoscopy in predicting surgical outcome
Authors: Jones Terry M. , Walker Paul , Ho Meau‐Shin , Earis John E. , Swift Andrew C. , Charters Peter
Published: August 2006

Objective

To assess the effectiveness of two grading systems used to predict surgical outcome in nonapneic snorers.

Study Design

A prospective observational study. Prior to undergoing palatal surgery, 20 patients completed a sleep nasendoscopic examination involving sequential steady‐state sedation with intravenous propofol. Using a combination of acoustic parameters of snoring sound as an objective outcome measurement, and the answers to a specifically designed questionnaire as a subjective outcome measurement, the effectiveness of each grading system in predicting surgical outcome was examined.

Results

Depending on the outcome measurement used, sensitivity in predicting success of surgery for snoring varied from 16.7% to 50.0% and specificity from 38.5% to 62.5% for the Pringle and Croft system, while sensitivity varied from 91.7% to 100% and specificity from 30.8% to 31.5% for the Camilleri system.

Conclusion

Sleep nasendoscopy using these classifications cannot be recommended as a reliable predictor of surgical outcome in nonapneic snorers.

EBM rating: C‐4
The application of vestibular‐evoked myogenic potentials in otoneurosurgery
Authors: Ernst Arne , Todt Ingo , Seidl Rainer O. , Eisenschenk Andreas , Blödow Alexander , Basta Dietmar
Published: August 2006

Objective

To evaluate the applicability of vestibular‐evoked myogenic potentials (VEMPs) in the diagnostics, intraoperative monitoring, and postoperative follow‐up of patients in otoneurosurgery.

Study Design

A prospective study of patients who underwent either cochlear implantation (CI, n = 18) or were diagnosed with an acoustic neuroma (AN, n = 9) or with neuro(micro)vascular compression of the VIIIth nerve (NVC, n = 27) in the period 2002 to 2004. The follow‐up was 1 year for all patients.

Setting

A tertiary‐referral unit.

Results

VEMPs could be recorded in 64% of all patients before CI and in 22% after surgery. The patients with AN had normal VEMPs in 22% of all cases when first diagnosed. Normal VEMPs were found in 37% of those patients with NVC. From the 5 AN patients who had to be operated, only 1 had intact VEMPs after surgery. In contrast, after microvascular decompression all patients (4) had normal VEMPs.

Conclusions

VEMPs are helpful in diagnosing patients with vertigo to better identify saccular defects. They are highly sensitive in the early diagnosis of retrocochlear lesions.

Significance

VEMPs can help to reliably identify patients with a retrocochlerar lesion at an early stage and can be used in intraoperative, neurophysiological monitoring.

EBM rating: C‐4
Aggressive maxillofacial disassembly in skull base surgery
Authors: Vladimir Zuzukin , Yadranko Ducic
Published: August 2006

Objective

To review our favorable experience with maxillofacial disassembly for exposure and resection of tumors of the skull base.

Patients and Methods

This is a retrospective review of 31 patients from 1997 to 2005 treated by maxillofacial disassembly and includes 22 patients with midface disassembly and 9 patients with mandible with or without midface disassembly.

Results

Follow‐up ranges from 2 weeks to 7 years: 23 of 31 patients are alive and disease free; 3 patients are alive with disease; 3 patients have died of distant metastasis. There were 14 complications in 12 (38.7%) patients; 13 of 14 complications were minor. One major complication (cardiovascular accident) resulted in the single postoperative mortality in this series.

Conclusion

Our technique of maxillofacial disassembly allows for tailored exposure of all regions of the anterolateral skull base with acceptable perioperative morbidity in appropriately selected patients.

EBM rating: C‐4