bluuebunny/crossref_metadata_2025 huggingface dataset:
Squishy Non‐Spherical Hydrogel Microparticles
Authors: Haghgooie Ramin , Toner Mehmet , Doyle Patrick S.
Published: September 2009

Recent advances in the synthesis of polymeric colloids have opened the doors to new advanced materials. There is strong interest in using these new techniques to produce particles that mimic and/or interact with biological systems. An important characteristic of biological systems that has not yet been exploited in synthetic polymeric colloids is their wide range of deformability. A canonical example of this is the human red blood cell (RBC) which exhibits extreme reversible deformability under flow. Here we report the synthesis of soft polymeric colloids with sizes and shapes that mimic those of the RBC. Additionally, we demonstrate that the mechanical flexibility of the colloids can be reproducibly varied over a large range resulting in RBC‐like deformability under physiological flow conditions. These materials have the potential to impact the interaction between biological and synthetic systems.

magnified image
Effect of Gold Nanoparticles on the Thermosensitivity, Morphology, and Optical Properties of Poly(acrylamide–acrylic acid) Microgels
Authors: Echeverria Coro , Mijangos Carmen
Published: September 2009

Novel positive thermosensitive microgels of poly(acrylamide–acrylic acid) with embedded gold nanoparticles have been synthesized and characterized by means of dynamic light scattering, UV‐vis spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. These systems show temperature (upper critical solution temperature‐like volume phase transition) and optical responsiveness making them externally triggered systems.

magnified image
Polyethylene Obtained by Plasma Polymerization of Hexene
Authors: Morales Pilar , Gómez Lidia M. , Olayo M. Guadalupe , Cruz Guillermo J. , Palacios Cuauhtemoc , Morales Juan , Ordoñez Eduardo
Published: September 2009

This work presents the synthesis by plasma of polyhexene (PHe) as an alternative to produce thin films of polyethylene (PE) without catalysts or other chemical compounds. PHe was obtained using 1‐Hexene in glow discharges at 13.5 MHz, 10−1 mBar and power between 40 and 120 W. The results showed that plasma PHe had the typical CC and CH bonds of PE with other bonds, as CC and CO, that indicate unsaturation and oxidation in the polymers. The thermal degradation of PHe starts at 250 °C, 100 °C lower than in PE. However, at T > 500 °C, PHe has more residual mass than PE. In the interval of 20–100 °C, the electrical conductivity of PHe was calculated between 10−11 and 10−8 S/cm. These results suggest that the structures of PHe and PE are similar and that the plasma polymerization of 1‐hexene is an alternative route to obtain oxidized and unsaturated varieties of PE as thin films on different surfaces.
Microemulsion Copolymerization Modeling Study Via a Combined Integral‐Differential Experimental Data Processing Approach
Authors: López‐Serrano F. , Mendizábal E. , Puig J.E. , Álvarez J.
Published: September 2009

On the basis of the data processing technique associated with the integro‐differential (ID) modeling assessment methodology, the styrene‐acrylonitrile microemulsion copolymerization system is studied, with a three‐state (conversion, active particles and micelles) and four‐parameter model (entrance and exit of radicals to and from particles, monomer transport from micelles to growing particles and initial micelle number), in conjunction with experimental conversion measurements. Comparing with the standard regression method, employed in previous studies, the ID approach incorporates additional information contained in the smooth conversion measurement derivative and does not require relying on a constant number of particles, as the slope‐and‐intercept method does. The resulting model, tested at three initiator concentrations, temperatures and comonomer feed, describes the S‐shaped conversion and the bell‐shaped active particles evolutions. This last finding is contrary to previous assumptions on linear growth with time of active particles. As expected, the entry and exit rate coefficients increase with initiator and styrene concentration and temperature. The surfactant transport from micelles decreases with initiator concentration and the initial micelles concentration value only affects the entry rate.
Evaluation of the Final Morphology of HIPS Based on the Architecture of the Compatibilizer Graft Copolymer PBd‐g‐PS
Authors: de Anda Carlos , Morales Graciela , Acuña Pablo , Sosa José , Knoeppel Dave , Mays Jimmy W.
Published: September 2009

High Impact Polystyrene (HIPS) was synthesized by radical bulk polymerization at 70 °C using 6% w/w of total rubber and 0.01% w/w of azobisisobutyronitrile (AIBN) as radical initiator, where the total rubber was composed by polybutadiene (PBd) and model graft copolymers PBd‐g‐PS. Different ratios in weight percent of PBd to PBd‐g‐PS were used in order to evaluate the effect of the graft copolymers on the morphology development of the rubber particles during the HIPS synthesis reaction. The morphology of the final material was evaluated by Transmission Electron Microscopy (TEM). The model graft copolymers used with controlled architecture and molecular weight were synthesized previously by high vacuum anionic polymerization. Results show that increasing the content and changing the architecture of the graft copolymer significantly affects the phase inversion point.
Photochromic Block Copolymer Poly(styrene‐b‐azo monomer) by ATRP
Authors: Vázquez Y. , Elizalde L.E. , Nájera M.A. , Santos G. de los , Telles J.G.
Published: September 2009

Photoactive monomers [(E)‐1(4‐methacryloxyphenyl)‐2‐(nitrophenyl) diazene] (azo 1) and (E)‐1‐(4‐methacryloxyethyl‐phenyl)‐2‐phenyl‐diazene (azo2) were synthesized. The azo 1 monomer showed poor reactivity under the evaluated polymerization method. The Azo 2 monomer was used in the block copolymerization with polystyrene by the normal ATRP methodology. Several polystyrene macroinitiators were prepared with molecular weights of 10, 20 and 30 k g/mol. The end functionality was increased by the addition of 0.1 equivalents of copper II chloride. Block copolymers in 30% yield and low polydispersity were synthesized by ATRP from the polystyrene macroinitiators and the azo monomer. The block copolymer exhibits good photochromic activity.
The Use of the RAFT‐Technique for the Preparation of Temperature/pH Sensitive Polymers in Different Architectures
Authors: Licea‐Claveríe Angel , Alvarez‐Sánchez Jesús , Picos‐Corrales Lorenzo A. , Obeso‐Vera Claudia , Flores Mercedes C. , Cornejo‐Bravo José Manuel , Hawker Craig J. , Frank Curtis W.
Published: September 2009

In this contribution we report the use of the RAFT‐technique for the preparation of three types of responsive polymeric materials with a high potential of application in the biomedical field: 1.‐Diblock copolymers with reversible self‐assembly capacity as a function of pH based on N,N′‐diethylaminoethyl methacrylate (DEAEM) and 2‐methacryloyloxy benzoic acid (MAOB); 2.‐Diblock copolymers with reversible self‐assembly capacity as a function of temperature, based N‐isopropylacrylamide (NIPAAm) and n‐hexyl acrylate (HA); and 3.‐Polymeric stars with random number of arms consisting either in NIPAAm‐arms or copolymeric NIPAAm‐arms and hydrophobic core.
Anionic Syntheses of Chain‐End and In‐Chain Functionalized Polymers by Silyl Hydride Functionalization and Hydrosilylation Chemistry
Authors: Quirk Roderic P. , Janoski Jonathan , Olechnowicz Michael , Kim Hoon , Dabney David E. , Wesdemiotis Chrys
Published: September 2009

A new general anionic functionalization methodology is described based on (a) the quantitative silyl hydride functionalization of well‐defined polymeric organolithium compounds with either dimethylchlorosilane (ω‐chain end functionalization) or dichloromethylsilane (in‐chain functionalization) and (b) reaction of the silyl hydride‐functionalized polymer with a functionalized alkene using Karstedt's Pt(0) hydrosilylation catalyst.
Poly(D‐lactide)–Poly(menthide)–Poly(D‐lactide) Triblock Copolymers as Crystal Nucleating Agents for Poly(L‐lactide)
Authors: Wanamaker Carolyn L. , Tolman William B. , Hillmyer Marc A.
Published: September 2009

Poly(d‐lactide)–poly(menthide)–poly(d‐lactide) (PDLA–PM–PDLA) triblock copolymers were explored as novel nucleating agents for the crystallization of poly‐ (l‐lactide) (PLLA). PLLA/PDLA‐PM‐PDLA blends containing ≥85 wt% PLLA were prepared in a batch melt mixer. SAXS analysis was consistent with the ability of PDLA–PM–PDLA to form micelles when mixed with atactic polylactide. The presence of the stereocomplex in the PLLA matrix was confirmed by differential scanning calorimetry (DSC). The effectiveness of the putative stereocomplexed micelle crystallites for nucleating PLLA crystallization was also confirmed by DSC. Nucleation efficiencies near 100% were obtained when using a triblock copolymer with 15 kg/mol PDLA end blocks. In addition, fast crystallization kinetics were observed in isothermal crystallization experiments at 140 °C. Compared to PLLA/PDLA homopolymer blends, improvements in nucleation efficiency were observed when blending PLLA with PDLA‐containing triblock copolymers.
One‐Pot Biocatalytic Synthesis of Sugar Based Poly (ε‐caprolactone)
Authors: Barrera‐Rivera Karla A. , Martínez‐Richa Antonio
Published: September 2009

The one‐pot biocatalytic synthesis of amphiphilic polymers consisting of an isosorbide headgroup and a hydrophobic polyester chain is described. The immobilized lipase of Yarrowia lipolytica (YLL) catalyzed ring‐opening polymerization of ε‐caprolactone (ε‐CL) initiated by the multifunctional initiator isosorbide. Polymerizations were carried out in bulk at 70, 80, 90 and 120 °C. The highest reaction rates for ε‐CL polymerization resulted for YLL immobilized on macroporous resins: Lewatit VP OC 1026 at 80 °C, and the strongly acidic Lewatit K‐2629 at 90 °C. Structural analyses were made by MALDI‐TOF, 1H, and 13C‐NMR.
Rapid Starch Acetylation at Low Temperature Using Iodine as Catalyst
Authors: Ramírez‐Arreola Daniel E. , Robledo‐Ortiz Jorge R. , Arellano Martín , González‐Núñez Rubén , Rodrigue Denis
Published: September 2009

Summary: A method to prepare starch acetate using acetic anhydride (AA) is presented. The process was carried out at temperatures below 100 °C using iodine (I) as a catalyst. The effect of reaction temperatures, as well as AA/starch and I/starch weight ratio was analyzed. The results show that high degrees of substitution can be reached by this method and the initial amount of acetic anhydride has a substantial effect on reaction efficiency. For a weight ratio of acetic anhydride to native starch (AA/AN) equal to two, a substitution degree of 3 was reached for 30 min and 70 °C.
Adsorption of Chitosan into SiO2 Monoliths Materials: Physical and Chemical Properties
Authors: Flores Norma I. Hinojosa , Ramírez Nelly Flores , Valencia Jaime Espino , García Salomón R. Vásquez , Bárcenas Gabriel Luna , García‐González Leandro
Published: September 2009

The dispersion of biopolymer chitosan on silica polymer matrix, prepared by the sol‐gel method under conditions of nearly linear chain growth, has allowed us obtain the beneficial properties of the large surface area of the dispersed SiO2 porous substrates. This study primarily aims to explore the chitosan adsorption in different weight ratios on silica monoliths by means solvent‐aided dispersion. The chitosan on SiO2 system has been investigated to know certain polymer properties, such as morphology, structure and thermal stability. The surface of the SiO2 monolith disks calcined (500 °C) employed as matrixes for chitosan were fractures free. SBET surfaces areas of these monoliths range from 452.99 m2/g. According to the FTIR analysis, the hydrogen bond there is an attractive intermolecular force between chitosan and SiO2. In contrast, the amino groups of the biopolymer are still accessible as active sites for heterogeneous catalysis. In addition, the thermostability of chitosan deposited on the monoliths was better than chitosan isolate.
Polymer Chain Collapse in Supercritical Fluids. 1. Molecular Simulation Results
Authors: Ortiz‐Estrada C. H. , Luna‐Bárcenas G. , Alvarado F. Javier , Gonzalez‐Alatorre G. , Sanchez I. C. , Castillo‐Tejas J. , Manero‐Brito O. , Ramírez N. Flores , García Salomón R. Vásquez
Published: September 2009

A few years ago we reported the first observation, by computer simulations, of polymer chain collapse near the lower critical solution temperature (LCST).1 In the present work, we extended the above study to understand the underlying physics of a single polymer chain collapse near LCST and its relationship to phase boundaries in the T‐x plane. Effects of solvent and monomer sizes, and solvent and monomer energetic interactions are studied. Using Monte Carlo simulations, the mean end‐to‐end distance (R) and gyration radius (Rg) are calculated for a single chain in a supercritical fluid solvent over a broad range of densities, pressures and temperatures. In general, the chain collapses as temperature increases at constant pressure. Upon a further temperature increase, the chain expands again to approach the athermal limit provided that the temperature is sufficiently high. The collapse is related to an LCST phase boundary while the expansion represents the signature of an upper‐critical solution temperature (UCST) suggesting the existence of a closed‐immiscibility loop. By manipulating the strength of the energetic interactions as well as the solvent‐to‐monomer size ratio, the size of the size of the immiscibility loop can be fine‐tuned. The relationship among size and the segment‐solvent energetic interaction are correlated by a conformational parameter (Ψ) for the first time. By monitoring the Ψ behavior, it is possible to predict solution's phase behavior, transition zone from LCST‐UCST in a closed‐loop miscibility behavior. The above relationship between chain conformation to phase boundaries may be useful in understanding phase stability in compressible polymer‐solvent mixtures.
Shelf Stability of Isocyanate‐Functionalized Vinyl Acrylic Latexes
Authors: Treviño María E. , Ramírez Jorge C. , Saade Hened , López Raúl G. , Ríos Leonardo
Published: September 2009

Copolymerization of vinyl acetate (VA) with butyl acrylate (BA) and dimethyl meta‐isopropenyl benzyl isocyanate (TMI) was carried out at 40 °C in emulsions stabilized with sodium dodecyl sulfate (SDS) or sodium dodecyl benzene sulfonate (SDBS). Regardless of the type of surfactant employed, latexes were very unstable during storage. Moreover, the hydrolysis of TMI and undesirable premature crosslinking of the polymeric chains did occur at room temperature during latexes storage.
Preparation and Characterization of Stable Aqueous Ferrofluids Using Low Molecular Weight Sulfonated Polystyrene
Authors: Ledezma Raquel , Bueno Darío , Ziolo Ronald F.
Published: September 2009

Summary: One of the most optically transparent magnetic materials known at room temperature consists of nanocrystalline γ‐Fe2O3 dispersed in a DVB cross‐linked sulfonated polystyrene (PS) matrix. When attrited dry or in water without surfactant and subsequently processed in water or water miscible liquids, the nanocomposite leads to a highly stable, low optical density ferrofluid with unique properties and uses in a variety of applications. We have heretofore identified the stabilizing agent in the ferrofluid as low molecular weight (∼6000) sulfonated PS, which results from attrition of the cross linked polystyrene nanocomposite. We report on the synthesis of low molecular weight (LMW) PS by atom transfer radical polymerization (ATRP) followed by sulfonation with acetyl sulfate and on the one‐step synthesis of a stable ferrofluid of nanocrystalline Fe3O4 using the newly synthesized LMW sulfonated PS. Physicochemical analyses and characterizations include GPC, GC‐MS, GPC, NMR, FTIR, XRD, TEM and magnetic data.
Monovalent Salt Effects on the Membrane Activity of Antimicrobial Polymers
Authors: Som Abhigyan , Choi Yeon , Tew Gregory N.
Published: September 2009

Synthetic mimics of antimicrobial peptides (SMAMPs) are known to disrupt cellular membranes in aqueous media. The impact of ionic strength, or the salt concentration, on membrane activity of these SMAMPs is an important issue since some AMPs are known to lose their activity at higher salt concentrations. In this report, the effect of salt concentration on membrane activity was evaluated using fluorescence dye leakage assays. Salt concentration did not affect the membrane activity of these SMAMPs significantly except for the 100% anionic vesicles (phosphatidylglycerol (PG) or phosphatidylserine (PS) only), where membrane activity decreased with increasing salt concentration. The results also indicated that the membrane activity of SMAMPs with monoamine side chains is independent on ionic strength against cardiolipin (CL) vesicles; however, SMAMPs containing bis‐ or tris‐ amines exhibited salt concentration dependent membrane activity for CL liposomes.
Recent Optical Applications of Perfluorocyclobutyl Aryl Ether Polymers
Authors: Mujkic Monika , Iacono Scott T. , Neilson Andrew R. , Smith Dennis W.
Published: September 2009

Summary: Perfluorocyclobutyl (PFCB) aryl ether polymers have various applications in the field of optics due to their synthetic versatility and availability, solution and melt processability, high temperature and photo stability, excellent optical transparency. Nanoparticle matrix materials, encapsulants, and chemical sensors are just a few examples of recent developments.
Obtainment of Graded Index Preforms by Combined Frontal Co‐Polymerization of MMA and BzMA
Authors: Villegas Armando García , Ocampo Miguel A. , Luna‐Bárcenas Gabriel , Saldívar‐Guerra Enrique
Published: September 2009

Summary. A simple system to obtain preforms with graded refraction index (GI) is presented. Index profiles with cylindrical symmetry are developed by introduction of a uniform rod of Poly Methylmethacrylate (65%)‐co‐Benzilmethacrylate (35%) (Poly‐(MMA‐co‐BzMA)) during mass copolymerization of an 80% MMA – 20% BzMA solution of the same monomers. The obtained preforms present a gradual variation of the refraction index with approximate radial symmetry. Dripping of the central bar produces moderate variations of the index profile along the preform axis, but a large enough fraction of the obtained preforms have potential to produce graded index (GI) polymer optical fibers (POF) by subsequent drawing and to obtain flat polymeric lenses by slicing.
Coarsening of PS/SAN Blends with Cocontinuous Morphology Studied with 3D Image Analysis
Authors: Lopez‐Barron Carlos R. , Macosko Christopher W.
Published: September 2009

Geometrical parameters of the interface in fluorescently labeled polystyrene (FLPS)/styrene‐ran‐acrylonitrile compolymer (SAN) blends with cocontinuous morphology were obtained on the basis of differential geometry of 3D images. Images were analyzed for time evolution of interfacial area, average mean and Gaussian curvatures, curvature distributions and topology. Annealing of a symmetric (50/50 FLPS/SAN w/w) and a non symmetric (35/65) blend was monitored. For the symmetric blend a linear time evolution of the characteristic length along with a self similar growth of the microstructure, evidenced by the dynamic scaling of the curvature probability densities, were observed. For the non symmetric blend, the more elongated domains of the minor phase, namely FLPS, broke up producing zones with droplet‐matrix structures coexisting with cocontinuous domains. Due to this morphological transition, dynamic scaling failed for the non symmetric blends. The number of holes on the interface, described by the genus, in a fixed sample volume decreases with time due to the growth of the microstructures and the formation of droplets.
The Transient Flow of the PET‐PEN‐Montmorillonite Clay Nanocomposite
Authors: Calderas F. , Sanchez‐Solis A. , Maciel A. , Manero O.
Published: September 2009

Polyethylene terephthalate (PET) and polyethylene 2, 6 naphthalene dicarboxylate (PEN) nanocomposites were prepared by an extrusion process with organic‐modified montmorillonite clay. The steady‐state viscosity of all blends diminished as compared to the system with no clay added. A rheological study was conducted to know more about the complex structure formed by the polymer matrix‐clay interactions. Instantaneous stress relaxation curves are presented for the PEN, PEN‐PET and PET‐PEN‐1phr clay systems. A Fourier Transform (FT) frequency response was obtained from the relaxation curves and compared to the linear oscillatory data, which lead to an extended frequency region. The results were modeled by a rheological equation of state which accounts for the formation‐destruction dynamics of the microstructure during flow. Relaxation time spectra are presented and compared for both rheological tests, namely, instantaneous stress relaxation and linear oscillatory flow. Additional studies using scanning electron microscopy (SEM) are presented, which reveal the presence of a slip layer in capillary flow for the system with added clay.
Macromol. Symp. 283–284
Authors: Licea‐Claveríe Angel , Alvarez‐Sánchez Jesús , Picos‐Corrales Lorenzo A. , Obeso‐Vera Claudia , Flores Mercedes C. , Cornejo‐Bravo José Manuel , Hawker Craig J. , Frank Curtis W.
Published: September 2009

Cover: The inaugural US‐Mexico Symposium on Advances in Polymer Science, MACROMEX 2008, took place in Los Cabos, Mexico. This first bi‐national conference was the result of a joint effort of the Mexican Polymer Society and the Polymer Chemistry Division of the American Chemical Society.

The cover is taken from the article of A. Licea‐Claveríe et al., p. 56, and shows the synthetic scheme for the preparation of polymeric stars with polyNIPAAm arms and crosslinked core by use of the RAFT‐methodology.
An open‐label conversion study of pramipexole to ropinirole prolonged release in Parkinson's disease
Authors: Lyons Kelly E. , Pahwa Rajesh
Published: September 2009

Ropinirole prolonged release (PR) is a once daily oral dopamine agonist approved for the treatment of Parkinson's disease (PD). The goal of this 4 week, open‐label study was to determine the most effective conversion ratio with the fewest adverse effects (AEs) when switching from pramipexole to ropinirole PR. Sixty patients with PD taking pramipexole were converted overnight to ropinirole PR at ratios of 1:3, 1:4, or 1:5 such that 20 consecutive subjects were enrolled in each group. Ropinirole PR dose adjustments were allowed to maintain efficacy or to reduce AEs. An overnight switch from pramipexole to ropinirole PR was found to be well tolerated and AEs were typical for a dopamine agonist. The most common AEs were worsening of PD symptoms, dizziness, somnolence, and nausea, the majority of which resolved after dose adjustments. Thirteen subjects discontinued ropinirole PR before 4 weeks. These subjects were taking a significantly greater dose of pramipexole, the majority greater than 4 mg/day, and tended to have longer disease durations. A conversion ratio of 1 mg of pramipexole to 4 mg of ropinirole PR resulted in the fewest discontinuations of ropinirole PR, the fewest dose adjustments and the largest percentage of subjects that preferred ropinirole PR. © 2009 Movement Disorder Society
Idiopathic REM sleep behavior disorder in the transition to degenerative disease
Authors: Postuma Ronald B. , Gagnon Jean‐Francois , Vendette Melanie , Montplaisir Jacques Y.
Published: September 2009

Idiopathic REM sleep behavior disorder (RBD) predicts Parkinson's disease (PD) and dementia. However, the nature of the disease that emerges from RBD has not been fully characterized. Since 2004, we have been conducting a prospective study of idiopathic RBD patients, providing an opportunity to directly observe patients as they transitioned to a defined neurodegenerative syndrome. Patients with idiopathic RBD underwent an extensive annual evaluation of motor function, olfaction, color vision, autonomic function, cognition and psychiatric symptoms. Neurodegenerative disease was defined according to standard criteria. We compared these measures in patients who had developed PD to those with dementia, all within the first year of developing disease. Of 67 patients, 6 developed PD and eleven developed dementia. Except for cognitive functioning, all tests of olfaction, color vision, autonomic function, depression, and quantitative measures of motor speed were similar in patients with PD and dementia. Of dementia patients, seven met criteria for probable Lewy body dementia (LBD) and four for Alzheimer's disease (or, possible LBD). In all probable LBD cases, the diagnosis was made because of parkinsonism, with no patient experiencing hallucinations or fluctuations. Patients with “Alzheimer's disease” seemed to have LBD, as they demonstrated typical LBD cognitive profiles on neuropsychological testing and were indistinguishable from LBD patients in ancillary measures. Therefore, among RBD patients with new‐onset LBD, hallucinations or fluctuations are absent, suggesting that RBD is a reliable early sign of LBD. The indistinguishability of dementia and PD in all ancillary measures suggests a single unitary “RBD‐then‐neurodegeneration” process, the clinical presentation of which depends upon selective neuronal vulnerability. © 2009 Movement Disorder Society
Modulation of ascorbic acid metabolism by cytochrome P450 induction revealed by metabonomics and transcriptional profiling
Authors: Aranibar Nelly , Bhaskaran Vasanthi , Ott Karl‐Heinz , Vassallo Jeff , Nelson David , Lecureux Lloyd , Gong Lei , Stryker Steve , Lehman‐McKeeman Lois
Published: September 2009

In the present study, NMR‐based urinary metabonomic profiles resulting from dosing with widely recognized microsomal enzyme inducers were evaluated in male rats. Wistar or Sprague–Dawley rats were dosed daily by oral gavage with phenobarbital (PB; 100 mg/kg), diallyl sulfide (DAS; 500 mg/kg), the investigational compound DMP‐904 (150 mg/kg), or β‐naphthoflavone (BNF; 100 mg/kg) for 4 days, and urine was collected daily for analysis. Compounds known to increase cytochrome P450 2B enzymes, including PB, DAS and DMP‐904, increased the urinary excretion of gulonic and ascorbic acid in a time‐dependent manner, reaching a maximum following 3–4 days of dosing. In contrast, BNF, an agent that induces primarily Cyp1A enzymes, did not increase gulonic or ascorbic acid excretion, despite inducing Cyp1A1 more than 200‐fold. Given the metabonomic results, hepatic transcriptional changes in the regulation of ascorbic acid biosynthesis were determined by RT‐PCR. All Cyp2B inducers increased hepatic mRNA levels of aldo‐keto reductase 1A1, an enzyme that catalyzes the formation of gulonic acid from glucuronate with concurrent decreased expression of both regucalcin (Rgn), the enzyme responsible for conversion of gulonic acid to gulono‐1, 4‐lactone and gulonolactone oxidase (Gulo), the rate‐limiting enzyme in ascorbate biosynthesis. These effects would be expected to increase levels of gulonic acid. In addition, Cyp2B inducers also increased hepatic expression of enzymes regulating ascorbic acid reutilization including glutaredoxin reductase (Glrx2) and thioredoxin reductase (Txnrd1). In contrast, BNF did not effect hepatic expression of any enzyme regulating gulonic or ascorbic acid biosynthesis. Thus, some microsomal enzyme inducers alter transcriptional regulation of ascorbic acid biosynthesis, and these changes are detected by noninvasive metabonomic profiling. However, not all microsomal enzyme inducers appear to alter ascorbic acid metabolism. Finally, the work illustrates how metabonomic results can direct additional studies to determine the biochemical mechanisms underlying changes in urinary metabolite excretion. Copyright © 2009 John Wiley & Sons, Ltd.
DOSY NMR applied to analysis of flavonoid glycosides from Bidens sulphurea
Authors: Rodrigues Edilene Delphino , da Silva Denise Brentan , de Oliveira Dionéia Camilo Rodrigues , da Silva Gil Valdo José
Published: September 2009

2D DOSY 1H NMR has proved to be a useful technique in the identification of the molecular skeleton of the four major compounds of ethyl acetate extract of aerial parts of Bidens sulphurea (Asteraceae). The combination of this technique with HPLC, mass spectrometry and other NMR techniques enabled the identification of four flavonoid glycosides: quercetin‐3‐O‐β‐D‐galactopyranoside, quercetin‐3‐O‐β‐D‐glycopyranoside, quercetin‐3‐O‐α‐L‐arabinofuranoside and quercetin‐3‐O‐β‐D‐rhamnopyranoside. Copyright © 2009 John Wiley & Sons, Ltd.
Anti‐ganglioside autoantibodies in type 1 diabetes
Authors: Lucchetta Marta , Rudilosso Salvatore , Costa Silvana , Bruttomesso Daniela , Ruggero Susanna , Toffanin Elisabetta , Faggian Diego , Plebani Mario , Battistin Leontino , Alaedini Armin , Briani Chiara
Published: September 2009

Type 1 diabetes is an autoimmune disease that is accompanied by an immune response against pancreatic cells. As gangliosides are expressed in both peripheral nerves and pancreatic cells, we examined the possibility of correlation between type 1 diabetes, anti‐ganglioside autoantibodies, and neuropathy. Fifty diabetic patients and 30 controls with other autoimmune diseases underwent neurological examination and search for antibodies to gangliosides, glutamic acid decarboxylase (GAD65), and tyrosine phosphatase (IA2). Sixteen (32%) diabetic patients had neuropathy. Twelve diabetic sera were found to have anti‐ganglioside autoantibodies. Twenty sera were positive for anti‐GAD65 and nine for anti‐IA2 antibody. Sera from three control patients had anti‐ganglioside autoantibodies. No significant correlation was found between autoantibodies, neuropathy, and disease duration. Disease duration was shorter in patients with antibodies to GAD65 and IA2 and longer in neuropathic patients. The higher prevalence of antibodies in diabetic patients compared to controls may reflect the common pattern of antigens shared by peripheral nerve and pancreatic islet cells. Muscle Nerve, 2009
C‐fiber function assessed by the laser doppler imager flare technique and acetylcholine iontophoresis
Authors: Green Alistair Q. , Krishnan Singhan T. , Rayman Gerry
Published: September 2009

Vasodilation induced by both acetylcholine iontophoresis (ACh Ionto) and the laser Doppler flare technique (LDIFT) can be used to measure small‐fiber function. The aim of this study was to compare the neurogenic nature of these methods. ACh Ionto and the LDIFT were performed on 10 controls, with and without local anesthetic cream. The local anesthetic cream blocks the axon reflex; thus, by determining the ratio of hyperemic area to stimulus area before and after anesthesia, the neurogenic nature of the hyperemia can be determined. The ratio of hyperemic area to stimulus area was significantly reduced by local anesthesia in the LDIFT [ratio (mean ± SD): 2.33 ± 0.67 with local anesthesia; 6.84 ± 1.33 without local anesthesia; P < 0.0001], whereas this ratio was unaffected by local anesthesia in the ACh Ionto group (2.61 ± 0.57 with local anesthesia; 2.67 ± 1.27 without local anesthesia). This study confirms that the LDIFT measures small‐fiber function. In contrast, hyperemia elicited by ACh Ionto outside the capsule is not blocked by local anesthesia and is thus non‐neurogenic. Muscle Nerve, 2009
Campylobacter jejuni abscess, encephalomyelitis, and acute polyradiculoneuropathy
Authors: Kamm Christian Philipp , Keserue Borbala , Humpert Sebastian , Wiest Roland , Nedeltchev Krassen , Hess Christian Walter , Arnold Marcel
Published: September 2009

We report an unusual case of spinal epidural Campylobacter jejuni abscess associated with acute polyradiculoneuropathy and parainfectious encephalomyelitis. Decompressive surgery, antibiotics, intravenous immunoglobulin (IVIg) therapy, and intravenous methylprednisolone resulted in rapid clinical improvement. C. jejuni infection can cause both an acute polyradiculoneuropathy as well as an encephalomyelitis, and a combined occurrence is possible. Muscle Nerve, 2009
Consensus statement: The use of intravenous immunoglobulin in the treatment of neuromuscular conditions report of the aanem AD HOC committee
Authors: Donofrio Peter D. , Berger Alan , Brannagan Thomas H. , Bromberg Mark B. , Howard James F. , Latov Normal , Quick Adam , Tandan Rup
Published: September 2009

Intravenous immunoglobulin (IVIG) is a therapeutic biologic agent that has been prescribed for over two decades to treat various neuromuscular conditions. Most of the treatments are given off‐label, as little evidence from large randomized trials exists to support its use. Recently, IGIV‐C has received an indication for the treatment of chronic inflammatory demyelinating polyneuropathy (CIDP). Because of the lack of evidence, an ad hoc committee of the AANEM was convened to draft a consensus statement on the rational use of IVIG for neuromuscular disorders. Recommendations were categorized as Class I–IV based on the strength of the medical literature. Class I evidence exists to support the prescription of IVIG to treat patients with Guillain–Barré syndrome (GBS), CIDP, multifocal motor neuropathy, refractory exacerbations of myasthenia gravis, Lambert–Eaton syndrome, dermatomyositis, and stiff person syndrome. Treatment of Fisher syndrome, polymyositis, and certain presumed autoimmune neuromuscular disorders is supported only by Class IV studies, whereas there is no convincing data to substantiate the treatment of inclusion body myopathy (IBM), idiopathic neuropathies, brachial plexopathy, or diabetic amyotrophy using IVIG. Treatment with IVIG must be administered in the context of its known adverse effects. There is little evidence to advise the clinician on the proper dosing of IVIG and duration of therapy. Muscle Nerve, 2009
Relief from episodic weakness with pyridostigmine in paramyotonia congenita: A family study
Authors: Khadilkar Satish V. , Singh R.K. , Mansukhani K.A. , Urtizberea J.A. , Sternberg D.
Published: September 2009

Pyridostigmine relieved episodic weakness in a family with paramyotonia congenita resulting from the R1448C mutation in the sodium channel gene. The transmission was autosomal dominant and the patients had paradoxical myotonia and exercise‐induced weakness. On electrophysiological studies there were myotonic potentials, and there was progressive reduction of compound muscle action potential (CMAP) amplitudes after short exercise associated with clinical weakness. Pyridostigmine in doses of 60 mg three times daily abolished the drop in the postexercise CMAP amplitude and reduced the amplitude decrement to slow rate repetitive stimulation, but there continued to be a drop in amplitude on exposure to cold. The decline of the CMAP amplitude on exposure to cold was controlled by treatment with phenytoin. The clinical and electrophysiological features are discussed in relation to therapy with pyridostigmine and phenytoin. Muscle Nerve, 2010
Normalization reduces the spatial dependency of the jaw‐stretch reflex activity in the human masseter muscle
Authors: Koutris Michail , Naeije Machiel , Lobbezoo Frank , Wang Kelun , Arendt‐Nielsen Lars , Svensson Peter , Farina Dario
Published: September 2009

The jaw‐stretch reflex is the short‐latency response in the jaw‐closing muscles after a sudden stretch. The hypothesis whether normalization of the jaw‐stretch reflex amplitude with respect to prestimulus electromyographic (EMG) activity will make the amplitude more independent of the location of the electrodes over the masseter muscle was tested. A 5 × 6 electrode grid was used to record the jaw‐stretch reflex from 25 sites over the right masseter muscle of 15 healthy men. The results showed that there was a significant site dependency of the prestimulus EMG activity and the reflex amplitude. High cross‐correlation coefficients were found between the spatial distribution of mean prestimulus EMG activities and reflex amplitude. When the reflex amplitude was normalized with respect to the prestimulus EMG activity, no site dependency was found. In conclusion, normalization of the jaw‐stretch reflex amplitude by the prestimulus EMG activity strongly reduces its spatial dependency. Muscle Nerve, 2010
Heteronymous Ia‐afferent connections in the upper limb following stroke
Authors: Lewis Gwyn N. , McNair Peter J.
Published: September 2009

Synergistic arm movement patterns are common following stroke and may arise through enhanced spinally mediated reflex connections between muscles. Our goal was to investigate the excitability of heteronymous Ia‐afferent pathways in people with chronic stroke. Responses to tendon taps of the flexor carpi radialis (FCR) muscle were recorded in FCR, biceps brachii (BB), and middle deltoid (MD) of 13 people with stroke and 13 controls. Heteronymous reflexes were elicited in BB and MD in some, but not all, stroke and control subjects. The prevalence and size of the heteronymous responses were not significantly different between groups. Homonymous reflex responses in FCR were significantly larger in the stroke group. We found that the excitability of heteronymous Ia‐mediated pathways from FCR to BB and MD muscles is not enhanced following stroke, despite exaggerated homonymous reflexes, and they are therefore not likely to contribute to coactivation of forearm and more proximal upper limb muscles. Muscle Nerve, 2010
Ultrasonographic Tinel sign
Authors: Chipman Joseph N. , Mott Ryan T. , Stanton Constance A. , Cartwright Michael S.
Published: September 2009

High‐resolution ultrasound has become increasingly useful in the evaluation of peripheral nerves. As we have gained experience, clinically helpful ultrasonographic signs have been detected. One of these is the ultrasonographic Tinel sign, in which paresthesias are produced when the transducer compresses a nerve lesion. This sign has not been previously described. We present a case in which the ultrasonographic Tinel sign helped accurately guide a nerve biopsy in a woman with mononeuritis multiplex. Muscle Nerve, 2009
Relationship of Q‐sweat to quantitative sudomotor axon reflex test (QSART) volumes
Authors: Sletten David M. , Weigand Stephen D. , Low Phillip A.
Published: September 2009

Q‐Sweat, a commercial quantitative sweat measurement system, is modeled on quantitative sudomotor axon reflex testing (QSART). This study investigated the sweat response using Q‐Sweat and Mayo‐QSART recordings under identical conditions in healthy normal controls. Ninety‐four participants were recruited for this study. All participants underwent randomized bilateral QSART recordings over the four standard recording regions. For both men and women, Wilcoxon signed rank tests of paired differences showed significantly lower volumes at each of the four sites for Q‐Sweat vs. Mayo‐QSART. Linear regression analysis was used to estimate the relationship between Q‐Sweat and Mayo‐QSART volume measurements separately for men and women. Although there was variability about the regression lines, these fitted models can be used to estimate the expected Mayo‐QSART volume given an observed Q‐Sweat volume, although it is preferable to use the Q‐Sweat normative database directly. We hypothesize that the constant‐current generator used in conjunction with Q‐Sweat provides a less efficient iontophoresis of acetylcholine than the Mayo‐constructed constant‐current stimulator and results in lower volumes. Muscle Nerve, 2010
Impairment of upper trapezius branch of the spinal accessory nerve during bypass grafting: A stretch injury?
Authors: Keleş Zelal , Zinnuroğlu Murat , Beyazova Mehmet
Published: September 2009

Internal jugular vein catheterization has been implicated in spinal accessory nerve (SAN) injuries after coronary artery bypass grafting (CABG). Stretch injury due to prolonged positioning during CABG has also been proposed as another mechanism of injury. Herein we describe a male patient with left shoulder pain and abduction difficulty following CABG, who displayed electromyographic abnormalities confined to the left upper trapezius muscle. Internal jugular vein catheterization had not been performed during surgery. Although unusual, the possibility of upper trapezius muscular branch paralysis should be considered in patients with shoulder pain or weakness after CABG. Muscle Nerve, 2010
Hand construction of quadrifilar wire electrodes for electromyography
Authors: Ahmed Omar I. , Roark Rick M.
Published: September 2009

Array electrodes have become increasingly popular for making surface and indwelling electromyographic (EMG) recordings. We describe a method for in‐house construction of indwelling quadrifilar fine‐wire electrodes. Quadrifilar electrodes facilitate the mapping of vector myoelectric signatures of motoneuron firing activities of the motor nucleus, a procedure referred to as EMG decomposition. The finished electrode has four detectors, each 50 μm in diameter, arranged in a rhombus pattern. Motor unit recruitment and firing information are aids to better understanding control deficits and behaviors evidenced in the final common pathway of the central nervous system. Muscle Nerve, 2009
Involvement of PI3K/Akt/TOR pathway in stretch‐induced hypertrophy of myotubes
Authors: Sasai Nobuaki , Agata Nobuhide , Inoue‐Miyazu Masumi , Kawakami Keisuke , Kobayashi Kunihiko , Sokabe Masahiro , Hayakawa Kimihide
Published: September 2009

Skeletal muscle cells are hypertrophied by mechanical stresses, but the underlying molecular mechanisms are not fully understood. Two signaling pathways, phosphatidylinositol 3‐kinase (PI3K)/Akt to target of rapamycin (TOR) and extracellular signal–regulated kinase kinase (MEK) to extracellular signal–regulated kinase (ERK), have been proposed to be involved in muscle hypertrophy. In this study we examined the involvement of these pathways in primary cultures of chick skeletal myotubes subjected to passive cyclic stretching for 72 hours, a time that was sufficient to induce significant hypertrophy in our preparations. Hypertrophy was largely suppressed by wortmannin or rapamycin, inhibitors of PI3K or mTOR, respectively. Furthermore, phosphorylation of Akt was enhanced by stretching and suppressed by wortmannin. The MEK inhibitor, U0126, exerted a minimal influence on stretch‐induced hypertrophy. We found that cyclic stretching of myotubes activates the PI3K/Akt/TOR pathway, resulting in muscle hypertrophy. The MEK/ERK pathway may contribute negatively to spontaneous hypertrophy. Muscle Nerve, 2010
Determinants of cognitive impairment in elderly myasthenia gravis patients
Authors: Marra Camillo , Marsili Francesca , Quaranta Davide , Evoli Amelia
Published: September 2009

The relationship between myasthenia gravis (MG) and cognitive dysfunction has been a matter of debate because of the possible association between peripheral and central nervous system (CNS) cholinergic dysfunction. The aim of this study was to evaluate cognitive function in a series of elderly MG patients in comparison to matched controls. In all, 100 consecutive MG patients aged over 60 years and 31 matched control subjects underwent an extensive neuropsychological test battery to explore multiple cognitive domains. There were no differences in cognitive performances between patients and controls. Severe MG was associated with impaired attention, constructional praxis, and frontal control. Logistic regression analysis showed that advanced age, diabetes, and thyroid dysfunction were independently associated with cognitive impairment. This study does not support the hypothesis of CNS cholinergic involvement in MG. The impairments of attention, memory, and control tasks in MG are related to general visual motor slowness and to the concomitant presence of other diseases. Muscle Nerve, 2009
Full SPH fluid–shell interaction for leakage simulation in explicit dynamics
Authors: Maurel B. , Potapov S. , Fabis J. , Combescure A.
Published: September 2009

This paper is devoted to the modeling of fluid leakage through a shell in case of impact loading. The modeling of the fluid and the shell is based on SPH formulation. The proposed model is devoted to the prediction of failure of a shell filled with fluid. This paper is devoted to the numerical modeling of fluid–structure interaction. The pinballs technique is used for contact analysis. Numerical predictions are compared with analytical as well as with an original experiment. Copyright © 2009 John Wiley & Sons, Ltd.
Meshless thermo‐elastoplastic analysis by triple‐reciprocity boundary element method
Authors: Ochiai Yoshihiro
Published: September 2009

In general, internal cells are required to solve thermo‐elastoplasticity problems by a conventional boundary element method (BEM). However, in this case, the merit of BEM, which is the easy preparation of data, is lost. A conventional multiple‐reciprocity boundary element method (MRBEM) cannot be used to solve elastoplasticity problems, because the distribution of initial strain or stress cannot be determined analytically. In this study, it is shown that without the use of internal cells, two‐dimensional thermo‐elastoplasticity problems can be solved by a triple‐reciprocity BEM using a thin plate spline. Initial strain and stress formulations are adopted and the initial strain or stress distribution is interpolated using boundary integral equations. A new computer program was developed and applied to solve several problems. Copyright © 2009 John Wiley & Sons, Ltd.
Non‐linear model reduction for uncertainty quantification in large‐scale inverse problems
Authors: Galbally D. , Fidkowski K. , Willcox K. , Ghattas O.
Published: September 2009

We present a model reduction approach to the solution of large‐scale statistical inverse problems in a Bayesian inference setting. A key to the model reduction is an efficient representation of the non‐linear terms in the reduced model. To achieve this, we present a formulation that employs masked projection of the discrete equations; that is, we compute an approximation of the non‐linear term using a select subset of interpolation points. Further, through this formulation we show similarities among the existing techniques of gappy proper orthogonal decomposition, missing point estimation, and empirical interpolation via coefficient‐function approximation. The resulting model reduction methodology is applied to a highly non‐linear combustion problem governed by an advection–diffusion‐reaction partial differential equation (PDE). Our reduced model is used as a surrogate for a finite element discretization of the non‐linear PDE within the Markov chain Monte Carlo sampling employed by the Bayesian inference approach. In two spatial dimensions, we show that this approach yields accurate results while reducing the computational cost by several orders of magnitude. For the full three‐dimensional problem, a forward solve using a reduced model that has high fidelity over the input parameter space is more than two million times faster than the full‐order finite element model, making tractable the solution of the statistical inverse problem that would otherwise require many years of CPU time. Copyright © 2009 John Wiley & Sons, Ltd.
Variationally consistent computational homogenization of transient heat flow
Authors: Larsson Fredrik , Runesson Kenneth , Su Fang
Published: September 2009

A framework for variationally consistent homogenization, combined with a generalized macro‐homogeneity condition, is exploited for the analysis of non‐linear transient heat conduction. Within this framework the classical approach of (model‐based) first‐order homogenization for stationary problems is extended to transient problems. Homogenization is then carried out in the spatial domain on representative volume elements (RVE), which are (in practice) introduced in quadrature points in standard fashion. Along with the classical averages, a higher order conservation quantity is obtained. An iterative FE2‐algorithm is devised for the case of non‐linear diffusion and storage coefficients, and it is applied to transient heat conduction in a strongly heterogeneous particle composite. Parametric studies are carried out, in particular with respect to the influence of the ‘internal length’ associated with the second‐order conservation quantity. Copyright © 2009 John Wiley & Sons, Ltd.