bluuebunny/crossref_metadata_2025 huggingface dataset:
Trajectory of development in adolescents and adults with autism
Authors: Seltzer Marsha Mailick , Shattuck Paul , Abbeduto Leonard , Greenberg Jan S.
Published: January 2005

This article seeks to elucidate the trajectory of development in adolescents and adults with autism. Prospective, retrospective, and cross‐sectional studies are reviewed to reveal the manifestation of and changes in the core symptoms of autism in adolescence and adulthood. Comparing children with adolescents and adults, modest degrees of symptom abatement and improvement in skills have been documented in multiple studies, as are increases in verbal and decreases in performance IQ. Nevertheless, most individuals do not attain normative outcomes in adulthood and continue to manifest significant degrees of symptomatology and dependency. However, a small sub‐group (about 15%) has more favorable adult outcomes. © 2004 Wiley‐Liss, Inc. MRDD Research Reviews 2004;10:234–247.
Designing mouse behavioral tasks relevant to autistic‐like behaviors
Authors: Crawley Jacqueline N.
Published: January 2005

The importance of genetic factors in autism has prompted the development of mutant mouse models to advance our understanding of biological mechanisms underlying autistic behaviors. Mouse models of human neuropsychiatric diseases are designed to optimize (1) face validity, i.e., resemblance to the human symptoms; (2) construct validity, i.e., similarity to the underlying causes of the disease; and (3) predictive validity, i.e., expected responses to treatments that are effective in the human disease. There is a growing need for mouse behavioral tasks with all three types of validity for modeling the symptoms of autism. We are in the process of designing a set of tasks with face validity for the defining features of autism: deficits in appropriate reciprocal social interactions, deficits in verbal social communication, and high levels of ritualistic repetitive behaviors. Social approach is tested in an automated three‐chambered apparatus that offers the subject a choice between a familiar environment, a novel environment, and a novel environment containing a stranger mouse. Preference for social novelty is tested in the same apparatus, with a choice between the start chamber, the chamber containing a familiar mouse, and the chamber containing a stranger mouse. Social communication is evaluated by measuring the ultrasonic distress vocalizations emitted by infant mouse pups and the parental response of retrieving the pup to the nest. Resistance to change in ritualistic repetitive behaviors is modeled by forcing a change in habit, including reversal of the spatial location of a reinforcer in a T‐maze task and in the Morris water maze. Mouse behavioral tasks that may model additional features of autism are discussed, including tasks relevant to anxiety, seizures, sleep disturbances, and sensory hypersensitivity. Applications of these tests include (1) behavioral phenotyping of transgenic and knockout mice with mutations in genes relevant to autism, (2) characterization of mutant mice derived from random chemical mutagenesis, (3) DNA microarray analyses of genes in inbred strains of mice that differ in social interaction, social communication and resistance to change in habit, and (4) evaluation of proposed therapeutics for the treatment of autism. Published 2004 Wiley‐Liss, Inc. MRDD Research Reviews 2004;10:248–258.
Neuroanatomical substrates of social cognition dysfunction in autism
Authors: Pelphrey Kevin , Adolphs Ralph , Morris James P.
Published: January 2005

In this review article, we summarize recent progress toward understanding the neural structures and circuitry underlying dysfunctional social cognition in autism. We review selected studies from the growing literature that has used the functional neuroimaging techniques of cognitive neuroscience to map out the neuroanatomical substrates of social cognition in autism. We also draw upon functional neuroimaging studies with neurologically normal individuals and individuals with brain lesions to highlight the insights these studies offer that may help elucidate the search for the neural basis of social cognition deficits in autism. We organize this review around key brain structures that have been implicated in the social cognition deficits in autism: (1) the amygdala, (2) the superior temporal sulcus region, and (3) the fusiform gyrus. We review some of what is known about the contribution of each structure to social cognition and then review autism studies that implicate that particular structure. We conclude with a discussion of several potential future directions in the cognitive neuroscience of social deficits in autism. © 2004 Wiley‐Liss, Inc. MRDD Research Reviews 2004;10:259–271.
Autism and 15q11‐q13 disorders: Behavioral, genetic, and pathophysiological issues
Authors: Dykens Elisabeth M. , Sutcliffe James S. , Levitt Pat
Published: January 2005

New insights into biological factors that underlie autism may be gained by comparing autism to other neurodevelopmental disorders that have autistic features and relatively well‐delineated genetic etiologies or neurobiological findings. This review moves beyond global diagnoses of autism and instead uses an endophenotypic approach to compare specific clusters of autistic symptomatology to features of chromosome 15q11‐q13 disorders. Paternally or maternally derived deficiencies of 15q11‐q13 result in Prader‐Willi or Angelman syndromes, and we first use a global approach to review potential autism susceptibility genes in the 15q11‐q13 region. We then use a more trait‐based approach to suggest possible ties between specific phenotypic characteristics of autism and Prader‐Willi syndrome, namely savant‐like skills. We conclude with insights from pathophysiological studies that implicate altered development of specific neuron types and circuits in the cerebral cortex as part of the pathophysiological processes associated with autism and mental retardation. © 2004 Wiley‐Liss, Inc. MRDD Research Reviews 2004;10:284–291.
Toward a developmental neurobiology of autism
Authors: Polleux Franck , Lauder Jean M.
Published: January 2005

Autism is a complex, behaviorally defined, developmental brain disorder with an estimated prevalence of 1 in 1,000. It is now clear that autism is not a disease, but a syndrome with a strong genetic component. The etiology of autism is poorly defined both at the cellular and the molecular levels. Based on the fact that seizure activity is frequently associated with autism and that abnormal evoked potentials have been observed in autistic individuals in response to tasks that require attention, several investigators have recently proposed that autism might be caused by an imbalance between excitation and inhibition in key neural systems including the cortex. Despite considerable ongoing effort toward the identification of chromosome regions affected in autism and the characterization of many potential gene candidates, only a few genes have been reproducibly shown to display specific mutations that segregate with autism, likely because of the complex polygenic nature of this syndrome. Among those, several candidate genes have been shown to control the early patterning and/or the late synaptic maturation of specific neuronal subpopulations controlling the balance between excitation and inhibition in the developing cortex and cerebellum. In the present article, we review our current understanding of the developmental mechanisms patterning the balance between excitation and inhibition in the context of the neurobiology of autism. © 2004 Wiley‐Liss, Inc. MRDD Research Reviews 2004;10:303–317.
Early detection of core deficits in autism
Authors: Sigman Marian , Dijamco Angeline , Gratier Maya , Rozga Agata
Published: January 2005

The goal of this review of the research literature is to discuss approaches to the early detection of autism in infancy. Early detection would enable diagnoses to be made before 18 months of age rather than at 24–30 months, the age where diagnoses start to be made now. After summarizing the criteria for a deficit to be considered “core” to the disorder, the literature on research strategies used in early detection is examined. In order to guide the design of future studies, the review then turns to an overview of what is known about the processes of early social development in typically developing children that underlie the domains in which core deficits are manifested in young children with autism. The social domains covered in the review are those that show development in typically developing infants below 18 months of age: dyadic interaction and imitation; emotion discrimination; and attachment. The review concludes that all of these areas are worthy of investigation in young children, particularly those at higher risk of showing some of the core deficits of autism such as the infant siblings of children with autism. © 2004 Wiley‐Liss, Inc. MRDD Research Reviews 2004;10:221–233.
Synthesis and characterization of novel rigid two‐photon absorbing polymers
Authors: Belfield Kevin D. , Yao Sheng , Morales Alma R. , Hales Joel M. , Hagan David J. , Van Stryland Eric W. , Chapela Victor M. , Percino Judith
Published: January 2005

Two‐photon absorbing polymers with alternating fluorenyl units as a π‐conjugated bridge and bisbenzothiazole or thiazolothiazole as electron‐acceptors were synthesized and characterized by IR, elemental analysis, absorption and fluorescence spectroscopy, and thermogravimetric analysis (TGA). Improvement on the solubility was observed in comparison with their phenyl based analogies. The linear absorption and emission spectra were recorded and high fluorescence quantum yields were found. Relatively large two‐photon absorption cross‐section per repeat unit (420 GM) were measured under fs‐pulsed laser excitation. Copyright © 2005 John Wiley & Sons, Ltd.
Preparation of nano‐sized UV‐absorbing titanium‐oxo‐clusters via a photo‐curing ceramer process
Authors: Soucek Mark D. , Johnson Aaron H. , Meemken Leon E. , Wegner Jonathan M.
Published: January 2005

A titanium sol‐gel precursor, titanium (IV) isopropoxide (TIP), was mixed with an epoxidized linseed oil (ELO). Using a cationic super‐acid photoinitiator, triarylsulfonium hexafluoroantimonate, both the organic phase (ELO) and the inorganic phase (TIP) were concomitantly cured. The exposure to moisture was strictly controlled before and during the UV‐curing process. The UV‐Visible spectra, SAXs (small angle X‐ray), DMA (dynamic mechanical properties), and contact angle were investigated as a function of sol‐gel precursor. The UV‐Visible spectra revealed that the inorganic/organic hybrid materials were more effective at blocking the UV‐light than nanoparticulate titanium dioxide while maintaining complete transparency in the visible region. The contact angle data indicated that the inorganic phase preferentially was concentrated at the film‐surface interface. The SAXs data was indicative of a 2‐‐5 nm titanium‐oxo‐cluster size, and the DMA data suggests a well distributed system. Copyright © 2005 John Wiley & Sons, Ltd.
Electrical properties of poly(2‐vinyl pyridine)/silica nanocomposites prepared with perhydropolysilazane
Authors: Saito Reiko , Tobe Tadakuni
Published: January 2005

Organic/silica nanocomposites were prepared by casting the blend solution of organic polymer, poly(2‐vinly pyridine‐co‐methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) or poly(2‐vinly pyridine‐co‐2‐hydroxyethyl methacrylate), and perhydropolysilazane and/or cobalt acetate. Electrical properties of the organic polymer and the composites were measured. Hybridization with perhydropolysilazane and/or cobalt acetate drastically reduced leakage current of the polymer film at 1 MV/cm from 1 × 10−7 to 1 × 10−9 A/cm2 without changing refractive index, dielectric constant and filed breakdown. Nanostructures and thermal stability of the composites were investigated. Copyright © 2005 John Wiley & Sons, Ltd.
Controlled synthesis of silicon‐containing polymers by metal catalysts
Authors: Kawakami Yusuke , Park Sung Young , Uenishi Kazuya , Oishi Motoi , Imae Ichiro
Published: January 2005

Silicon‐containing polymers with definite chemical structure were synthesized by reaction of silanes with compounds having multiple bonds (polyaddition) and with water (polycondensation), and by ring‐opening reactions of silacyclobutane or butene derivatives (ring‐opening polymerization). Various optically pure organosilicon compounds were synthesized or separated by HPLC, and stereoregular polycarbosilanes, polycarbosiloxanes and polysiloxanes were synthesized from these compounds used as monomers. Stereochemistry of the elementary reactions producing stereoregular polymers was elucidated. Copyright © 2003 Society of Chemical Industry
The synthesis of functional star copolymers as an illustration of the importance of controlling polymer structures in the design of new materials
Authors: Matyjaszewski Krzysztof
Published: January 2005

Several different methods for the synthesis of star copolymers employing atom transfer radical polymerization are presented. They include core‐first and arm‐first methods, and a combination of both to prepare mikto‐arm stars. Stars with a well‐defined number of arms were prepared by using a core with a precise number of functional groups, and ill‐defined stars were prepared from hyperbranched cores. In addition, end‐functional stars were prepared by either displacing end‐functional halogens or through radical addition with unreactive functional alkenes. Another approach to end‐functional stars employs functional initiators and the subsequent coupling of the end‐functional arms with difunctional vinyl monomers. Star‐like backbones were also used to grow star‐like macromolecular brushes that were visualized by AFM. The polydispersities of individual arms and entire stars followed Schulz–Flory statistics. Copyright © 2003 Society of Chemical Industry
Electroactive macromonomers based on pyrrole and thiophene: a versatile route to conducting block and graft polymers
Authors: Yagci Yusuf , Toppare Levent
Published: January 2005

The synthesis of block and graft copolymers containing insulating and conducting polypyrrole or polythiophene segments via a two‐step procedure is described. Synthetic pathways to prepare pyrrole and thiophene functional macromonomers involving conventional and controlled/living polymerizations such as anionic and cationic ring opening, atom transfer radical polymerization are discussed. The use of these macromonomers in subsequent electrochemical and chemical polymerizations, leading to the formation of copolymers, is presented. Copyright © 2003 Society of Chemical Industry
Synthesis of polymeric topological isomers through electrostatic self‐assembly and covalent fixation with telechelic poly(THF) having cyclic ammonium salt groups
Authors: Tezuka Yasuyuki , Tsuchitani Akiko , Oike Hideaki
Published: January 2005

A pair of macromolecular constitutional isomers having topologically distinctive constructions, ie θ‐shaped and manacle‐shaped polymers, has been synthesized through covalent conversion of an electrostatic polymer self‐assembly comprised of bifunctional linear poly(tetrahydrofuran) [poly(THF)] having N‐phenylpyrrolidinium salt end groups carrying tricarboxylate counteranions (1) under various dilutions. The presence of the two constitutional polymeric isomers was revealed by means of a reverse‐phase liquid chromatography (RPLC) technique. Moreover, size‐exclusion chromatography (SEC) confirmed that one major component possesses notably larger hydrodynamic volume than another, and is assigned as a manacle‐shaped isomer while a minor component as a θ‐shaped isomer. Further details of this unique process were investigated by RPLC analysis of topological isomer products obtained from a series of poly(THF) precursors, 1, having different molecular weights. Copyright © 2003 Society of Chemical Industry
New approach for the synthesis of amino‐containing linear polymers
Authors: Van De Velde Peggy , Goethals Eric J , Du Prez Filip
Published: January 2005

A new approach for the synthesis of well‐defined poly(aminoethyl vinyl ether)s with controllable molecular weight has been developed. In a first step poly(chloroethyl vinyl ether)s with narrow molecular weight were prepared via living cationic polymerization of chloroethyl vinyl ether with 1,1‐diethoxyethane/trimethylsilyl iodide/zinc iodide as initiating system. The chloro groups of the resulting polymers were subsequently substituted into phthalimide groups, resulting in the formation of poly(phthalimide ethyl vinyl ether). Hydrazinolysis of the imide functions gave rise to the desired poly(aminoethyl vinyl ether)s. The polymers were characterized by 1H NMR, size exclusion chromatography and X‐ray spectroscopy. The resulting polyamine was soluble only in water and in methanol and showed polyelectrolyte behaviour, as revealed by viscosimetry studies. Copyright © 2003 Society of Chemical Industry
Energy transfer in polystyrene containing pendant stilbene chromophores
Authors: Wuyts Cindy , Dermaut Wim , Hoefnagels Roel , Aerts Gert , Goovaerts Etienne , Geise Herman J
Published: January 2005

Four different styrene copolymers with stilbenoid side chains were synthesised under Williamson ether or Wadsworth–Emmons conditions. Blends of these graft copolymers with 4,4′‐bis[2,2‐bis(4‐methoxyphenyl)ethenyl]biphenyl (TMBiPPT), a good blue light emitting oligomer, yielded efficient host–guest systems with only emission from the oligomer. TMBiPPT has a maximum absorption at 365 nm, and the emission spectra of the synthesised graft copolymers all had a significant spectral overlap with the absorption spectrum of TMBiPPT. Since we can tune both the structures of the graft copolymer and the oligomer, this is very promising for obtaining new materials to use in a single‐layer OLED (organic light emitting diode). Copyright © 2003 Society of Chemical Industry
Synthesis and characterisation of water‐soluble poly(ethylene glycol) modified polymethacrylates with the ability to crosslink
Authors: Snellings Geert , Mondelaers Wim , Schacht Etienne
Published: January 2005

Hydrogels have become increasingly important in the biomedical field. The aim of this study was to develop amphiphilic poly(ethylene glycol) grafted polymethacrylates with curable side groups. The water‐soluble polymers were synthesised by free‐radical copolymerisation of methyl methacrylate, α‐methyl‐ω‐methacroyl‐poly(ethylene glycol) and 2‐hydroxyethyl methacrylate (HEMA). The methacrylate containing hydrogel precursors were obtained by reacting the free hydroxyl groups of HEMA in the polymer with methacrylic anhydride in the presence of catalyst. γ‐Irradiation has been used as an elegant method for crosslinking and simultaneous sterilisation. The influence of the irradiation dose (5, 15, 25 kGy) on the polymers was examined by the determination of the gel and sol fraction. In an aqueous environment these materials behave as hydrogels with more swelling at lower temperatures. Since the coatings can be applied in mild conditions, eg water, these materials are looking very promising as thin film coatings for biomedical applications. Copyright © 2003 Society of Chemical Industry
Micropatterning polyurethane surfaces with lasers
Authors: Martelé Yves , Naessens Kris , Van Daele Peter , Baets Roel , Callewaert Kristof , Schacht Etienne
Published: January 2005

The ablation properties of a series of segmented polyurethanes were investigated after irradiation with excimer lasers (ArF and KrF). The building blocks of the polymers were varied to make a correlation between the chemical structure and the ablation properties (absorption coefficient and threshold value). The aromatic compounds in the segmented polyurethanes were responsible for the KrF excimer laser ablation sensitivity. Polymers with aromatic diisocyanates had the highest absorption coefficient and lowest threshold value. The polymers with only aliphatic compounds could be classified as low absorbing polymers though, the use of ArF excimer laser with aliphatic polymers led to ablation, with formation of well‐defined cavities. In conclusion, the segmented polyurethanes were more sensitive to ArF excimer laser ablation. Copyright © 2003 Society of Chemical Industry
Synthesis of poly(spiroacetal–ether)s
Authors: Maślińska‐Solich Jolanta , Kukowka Sylwia
Published: January 2005

Poly(spiroacetal–ether)s were prepared by two alternative synthetic paths (alkaline and acid‐catalysed conditions). Polycondensation of 3,9‐di‐(2‐hydroxyphenyl)‐2,4,8,10‐tetraoxaspiro[5,5]undecane and 1,4‐dibromobutane was performed in solvents (n‐butyl acetate, N,N‐dimethylformamide, dimethyl/sulfoxide) catalysed by K2CO3 or KOH/PTC systems. A similar polymer was formed in the reaction of 2,2‐dihydroxymethyl‐1,3‐propanediol with 1,4 bis(2‐formylphenoxy)butane, catalysed by p‐toluenesulfonic acid. The molecular weight was determined by gel‐permeation chromatography. 1H and 13C NMR were used to study the details of the polymer structure. Copyright © 2003 Society of Chemical Industry
Alternating poly(ester amide)s from succinic anhydride and α,ω‐amino alcohols: synthesis and thermal characterization
Authors: Fey Thomas , Hölscher Markus , Keul Helmut , Höcker Hartwig
Published: January 2005

Alternating poly(ester amide)s 6a–e from succinic anhydride and α,ω‐amino alcohols H2N—(CH2)x—OH (x = 2–6) 2a–e were obtained in two steps: α‐carboxyl‐ω‐hydroxy amides 3a–e were prepared from the starting materials in a highly selective reaction, followed by a polycondensation reaction. 1H and 13C NMR analyses of the poly(ester amide)s clearly reveal the alternating microstructure. The poly(ester amide)s with homologous α,ω‐amino alcohols H2N—(CH2)x—OH (x = 2–6) are semi‐crystalline materials, their melting points show the odd/even effect observed for [n]‐polyamides and [n]‐polyurethanes. Heating the poly(ester amide)s 6a–e yields the corresponding N‐(hydroxyalkyl) imides 4a–e with no trace of cyclic ester amides. Theoretical calculations revealed that the cyclic ester amides 5a–e are clearly richer in energy than the isomeric N‐(hydroxyalkyl) imides. These results show that cyclic ester amides can not be prepared from N‐(hydroxyalkyl) imides by ring‐enlargement reactions. Copyright © 2003 Society of Chemical Industry
Preparation of linear low‐density polyethylene by the in situ copolymerization of ethylene with an iron oligomerization catalyst and rac‐ethylene bis(indenyl) zirconium (IV) dichloride
Authors: Zhang Zhicheng , Cui Nannan , Lu Yingying , Ke Yucai , Hu Youliang
Published: January 2005

An iron oligomerization catalyst, [(2‐ArNC(Me))2C5H3N]FeCl2 [Ar = 2,6‐C6H3(F)2], was combined with rac‐ethylene bis(indenyl)zirconium (IV) dichloride [rac‐Et(Ind)2ZrCl2] to prepare linear low‐density polyethylene (LLDPE) by the in situ copolymerization of ethylene. A series of LLDPEs with different properties were prepared by the alteration of the reaction temperature, Fe/Zr molar ratio, Al/(Fe + Zr) molar ratio, and reaction time. The structures of the polymers were characterized with differential scanning calorimetry, 13C NMR, gel permeation chromatography (GPC), and so forth. The melting points, crystallizations, and densities of the resulting products increased, and the average branching degree decreased, as the reaction temperature, Al/(Fe + Zr) ratio, and reaction time increased. The melting points, crystallizations, and densities of the polymers decreased, and the average branching degree increased, when the Fe/Zr ratio increased. The 13C NMR and GPC results showed that there were no unreacted α‐olefins remaining in the resulting polymers because the percentage of low‐molar‐mass sections (C4–C10) of the oligomers obtained with this catalyst was very high (>70%). In addition, the formation of polymers with two melting points under different reaction conditions was examined in detail, and the results indicated that the two melting points of the polymers could be attributed to polyethylene with different branches. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 984–993, 2005
Synthesis and mass spectrometry characterization of centrally and terminally amine‐functionalized polyisobutylenes
Authors: Wollyung Kathleen M. , Wesdemiotis Chrys , Nagy Andras , Kennedy Joseph P.
Published: January 2005

This article reports the facile synthesis of novel terminally and centrally functionalized polyisobutylenes (PIBs) and the detailed characterization of the products by various mass spectrometry techniques. Specifically, HPIBCH2C(OH)CH3CH2NHCH3 and [HPIBCH2CH(OH)CH3CH2]2NCH3 were synthesized by the quantitative epoxidation of HPIBCH2C(CH3)CH2 and the subsequent conversion of the resulting epoxide with excess CH3NH2. Quaternization with CH3Cl of these mixtures of secondary and tertiary amines yielded exclusively HPIBCH2C(OCH3)CH3CH2N(CH3)2 from the secondary amine, whereas the tertiary (centrally functionalized) amine remained unchanged. Tandem mass spectrometry experiments provided unique insight into the precise connectivity of the functional end groups added to the PIB frame. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 946–958, 2005
Average termination rate coefficients in emulsion polymerization: Effect of compartmentalization on free‐radical lifetimes
Authors: Prescott Stuart W. , Ballard Mathew J. , Gilbert Robert G.
Published: January 2005

A method is presented by which the time‐dependent average termination rate coefficient in an emulsion polymerization may be calculated as an appropriate average of the chain‐length‐dependent termination rate coefficients. The method takes advantage of the fact that the overall termination rate is dominated by terminations between rapidly moving short radicals and much slower long ones. This termination rate coefficient is suitable for use in the Smith–Ewart equations describing the compartmentalization of radicals in an emulsion polymerization. Rate data in emulsion polymerizations can be quantitatively interpreted if the kinetics fall into one of two categories: zero–one (showing compartmentalization; intraparticle termination is not rate‐determining) or pseudo‐bulk (no compartmentalization; intraparticle termination is rate‐determining). The new method can be used to interpret rate data for systems falling between these categories and also can be used to find termination rate coefficients from Monte Carlo simulations of termination kinetics. The latter is especially useful for predicting and understanding kinetics in controlled radical polymerizations in disperse media. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1076–1089, 2005
Synthesis and optical properties of green‐light‐emitting copolymers containing side‐chain oxadiazole units
Authors: Tzanetos Nikos P. , Kallitsis Joannis K.
Published: January 2005

Atom transfer radical polymerization was used to prepare well‐defined vinyl polyoxadiazole homomacromonomers with a properly modified α‐dicarboxylic acid methyl ester as the initiator. Macromonomers of various molecular weights with narrow polydispersities in some cases were obtained, as proved by gel permeation chromatography (GPC). The structures of the obtained macromonomers were then identified with 1H NMR spectroscopy. These macromonomers were subsequently copolymerized with a dihydroxy anthracene based monomer by a polycondensation technique, and this resulted in polymacromonomers. Coil–rod–coil copolymers containing side‐chain anthracene and oxadiazole units were also synthesized by atom transfer radical polymerization. The resulting copolymers combined an anthracene derivative as the rigid block with a random copolymer of the desired anthracene‐ and/or oxadiazole‐based monomers as the flexible block. These copolymers were primarily characterized with GPC and 1H NMR techniques. Additionally, the optical properties of all these copolymers were investigated in detail, and they suggested energy transfer from the oxadiazole to the anthracene chromophores, which became much more efficient in the solid state. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1049–1061, 2005
Construction of a polymer skeleton that is cut in half by ionizing radiation
Authors: Shimizu Takashi , Ichikawa Tsuneki
Published: January 2005

Polystyrene with a benzyl ester of carboxylic acid at the center of a polymer skeleton was synthesized by living radical polymerization. The initiator used had two functional groups for 2,2,6,6‐tetramethylpiperidinoxyl (TEMPO)‐mediated living radical polymerization on the benzyl and the carboxylic sides of the benzyl ester. Introduction of the benzyl ester changed the polystyrene from a crosslink type to a scission type polymer on γ‐irradiation. Irradiation of the polymer resulted in a binary change of the molecular weight because of the dissociative capture of secondary electrons by the benzyl ester, as:

The binary change of the molecular weight suggests that the polymer can be used as a new type of radiation resist with high sensitivity and spatial resolution to ionizing and high resistivity to plasma etching. The number of scissions per 100 eV radiation energy absorbed was 0.29, which was about one fourth of the yield of secondary electrons. The low efficiency was because of the recombination of polymer radicals generated by the dissociative electron attachment. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1068–1075, 2005
Polyelectrolyte multilayers prepared on hydrogel surfaces
Authors: Serizawa Takeshi , Sakaguchi Hirokazu , Matsusaki Michiya , Akashi Mitsuru
Published: January 2005

Poly(vinyl alcohol) hydrogels were alternately immersed in aqueous solutions of oppositely charged polymers. The adsorption of the cationic dye methylene blue to the immersed hydrogels suggested the presence of a coating on the hydrogel surfaces. Static contact angles with an air bubble in water showed layer‐by‐layer growth of the films. The films could be transferred onto solid substrates for mechanical strength after the hydrogels were placed on the solid substrates, and this resulted in an estimation of the film thickness. The number of assembly steps could regulate the film thickness. We present here coatings of hydrogels with thin polymer films prepared by layer‐by‐layer assembly. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1062–1067, 2005
Splicing mutation in the fibrillin‐1 gene associated with neonatal Marfan syndrome and severe pulmonary emphysema with tracheobronchomalacia
Authors: Shinawi Marwan , Boileau Catherine , Brik Riva , Mandel Hanna , Bentur Lea
Published: January 2005

Neonatal Marfan syndrome is an autosomal‐dominant connective tissue disease with unique clinical manifestations and mutations. We describe the clinical course of an infant with neonatal Marfan syndrome that had the novel IVS31‐2A > G splice site mutation in fibrillin‐1. This mutation affects the second base of the acceptor consensus splice site of intron 31, and probably leads to abnormal splicing events. The patient presented with respiratory distress and heart murmur in early neonatal life. Cardiac evaluation revealed pulmonic stenosis, atrioventricular regurgitation, and a dilated aortic root that were controlled by balloon dilatation of the pulmonic stenosis and medications for congestive heart failure. At age 3 months, he presented with severe respiratory distress caused by upper and lower airway obstruction. Imaging studies showed severe pulmonary emphysema, and a bronchoscopy demonstrated megatracheobronchomalacia, an unusual finding in this syndrome. Subsequently, the patient developed recurrent hyperinflation of the right and left lungs, with emphysematous changes and mediastinal shift. After discussing with his parents the grave prognosis for neonatal Marfan syndrome, he was discharged home with oxygen treatment and died at home at age 4.5 months. This case report demonstrates and discusses pulmonary involvement in neonatal Marfan syndrome and the difficult therapeutic challenges created by the severe cardiopulmonary abnormalities in this invariably fatal condition. Pediatr Pulmonol. 2005; 39:374–378. © 2005 Wiley‐Liss, Inc.
Receptor for advanced glycation end products (RAGE) and its ligand, amphoterin are overexpressed and associated with prostate cancer development
Authors: Ishiguro Hitoshi , Nakaigawa Noboru , Miyoshi Yasuhide , Fujinami Kiyoshi , Kubota Yoshinobu , Uemura Hiroji
Published: January 2005

BACKGROUND

Advanced glycation end products (AGE) are produced with normal aging. Recently, some reports indicated that the interaction between AGE and the cognate receptor (RAGE) has a role in cancer dependent.

METHODS

We investigated RAGE and amphoterin mRNA expression in prostate cancer cell lines (DU145, PC‐3, and LNCaP cells), hormone‐refractory prostate cancer tissues, and paired untreated primary prostate cancer and normal prostate (including benign prostatic hypertrophy (BPH)) tissues using real‐time quantitative PCR. Moreover, to confirm the AGE–RAGE interaction in prostate cancer, DU145 cells stimulated with AGE–bovine serum albumin (AGE–BSA) were examined by in vitro matrigel assay, cell viability assay, MTT assay, reverse transcription‐polymerase chain reaction (RT‐PCR), and Western blot.

RESULTS

DU145 cells, a hormone‐independent prostate cancer cell line, showed the highest RAGE mRNA expression. Amphoterin mRNA was expressed in all three cell lines. In prostate tissues, untreated prostate cancer tissue and hormone‐refractory prostate cancer tissue showed higher RAGE and amphoterin mRNA expression than normal prostate tissue. The AGE–RAGE interaction induced the invasion and growth in DU145 cells stimulated with AGE–BSA.

CONCLUSIONS

The AGE–RAGE interaction is important in prostate cancer development, and inhibition of this interaction has potential as a new molecular target for cancer therapy or prevention. © 2005 Wiley‐Liss, Inc.
Prediction of interfaces for oligomerizations of G‐protein coupled receptors
Authors: Nemoto Wataru , Toh Hiroyuki
Published: January 2005

Several lines of biochemical and pharmacological evidence have suggested that some G‐protein‐coupled receptors (GPCRs) form homo oligomers, hetero oligomers or both. The GPCRs oligomerizations are considered to be related to signal transduction and some diseases. Therefore, an accurate prediction of the residues that interact upon oligomerization interface would further our understanding of signal transduction and the diseases in which GPCRs are involved. One of the complications for such a prediction is that the interfaces differ with the subtypes, even within the same GPCR family. Focusing on the distribution of residues conserved on the molecular surface in a particular subtype, we developed a new method to predict the interface for the GPCR oligomers, and applied it to several subtypes of known GPCRs to check the sensitivity. Subsequently, we found that predicted interfaces of rhodopsin, D2 dopamine receptor and β2 adrenergic receptor agreed with the experimentally suggested interfaces, despite difference in the interface region among the three subtypes. Moreover, a highly conserved residue detected from the D2 dopamine receptor corresponded to a residue involved in a missense change found in the large family of myoclonus dystonia. Our observation suggests the possibility that the disease is caused by the disorder of the oligomerization, although the molecular mechanism of the disease has not been revealed yet. The benefits and the pitfalls of the new method will be discussed, based on the results of the applications. Proteins 2005. © 2004 Wiley‐Liss, Inc.
Parametric oscillation in semiconductor microcavities: nonlinear and quantum effects
Authors: Karr J. Ph. , Baas A. , Romanelli M. , Bramati A. , Giacobino E.
Published: January 2005

We report the observation of optical bistability in a semiconductor microcavity pumped at the “magic angle” above the parametric oscillation threshold. Experimental evidence is given in the form of a hysteresis cycle of the nonlinear emission as a function of the pump intensity. A model analogous to those developped for triply resonant Optical Parametric Oscillators (OPO) is in good agreement with the experimental findings. In the second part, we study the potential application of the parametric oscillation regime to quantum optics. The quantum correlations between the emitted “signal” and “idler” beams are computed. We show that very strong quantum correlations between the signal and idler polaritons can be achieved. However the quantum effects in the outgoing light fields are strongly reduced due to the large mismatch in the coupling of the signal and idler polaritons to the external photons. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Giant light absorption by plasmons in a nanoporous metal film
Authors: Teperik T. V. , Popov V. V. , García de Abajo F. J.
Published: January 2005

We have calculated the light absorption spectra of a metal film containing a hexagonal two‐dimensional lattice of spherical nano‐voids. It is shown that giant resonant absorption of light occurs at the plasma resonance of the void lattice in the visible when the void‐to‐surface distance and the inter‐void spacing are thinner than the skin depth. The maximum absorbance, at plasma resonance, is shown to be 50%. This phenomenon occurs when the void‐to‐surface distance has a specific value, which ensures optimal coupling of plasmons in the voids to the external light. We have found a physical criterion for the optimal coupling, which reads that the radiative broadening of the plasma resonance must be equal to its dissipative broadening in order to produce maximum light absorption at the resonance. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Closely spaced external standard: a universal method of achieving 5 ppm mass accuracy over the entire MALDI plate in axial matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Moskovets Eugene , Chen Hsuan‐Shen , Pashkova Anna , Rejtar Tomas , Andreev Viktor , Karger Barry L.
Published: January 2005

Close deposition of the sample and external standard was used in axial matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) to achieve mass accuracy equivalent to that obtained with an internal standard across the entire MALDI plate. In this work, the sample and external standard were deposited by continuous deposition in separate traces, each approximately 200 μm wide. The dependence of the mass accuracy on the distance between the sample and standard traces was determined across a MALDI target plate with dimensions of 57.5 mm × 57.0 mm by varying the gap between the traces from 100 μm to 4 mm. During acquisition, two adjacent traces were alternately irradiated with a 200‐Hz laser, such that the peaks in the resulting mass spectra combined the sample and external standard. Ion suppression was not observed even when the peptide concentrations in the two traces differed by more than two orders of magnitude. The five peaks from the external standard trace were used in a four‐term mass calibration of the masses of the sample trace. The average accuracy across the whole plate with this method was 5 ppm when peaks of the sample trace had signal‐to‐noise ratios of at least 30 and the gap between the traces was approximately 100 μm. This approach was applied to determining peptide masses of a reversed‐phase liquid chromatographic (LC) separation of a tryptic digest of β‐galactosidase deposited as a long serpentine trace across the MALDI plate, with accuracy comparable to that obtainable using internal calibration. In addition, the eluent from reversed‐phase LC separation of a strong cation‐exchange fraction containing tryptic peptides from a yeast lysate along with the closely placed external standard was deposited on the MALDI plate. The data obtained in the MS and MS/MS modes on a MALDI‐TOF/TOF mass spectrometer were combined and used in database searching with MASCOT. Since the significant score is a function of mass accuracy in the MS mode, database searching with high mass accuracy reduced the number of false positives and also added peptides which otherwise would have been eliminated at lower mass accuracy (false negatives). Copyright © 2003 John Wiley & Sons, Ltd.
Improvement of electron capture efficiency by resonant excitation
Authors: Mormann Michael , Peter‐Katalinić Jasna
Published: January 2005

A novel pulse sequence improving the efficiency for electron capture dissociation (ECD) of an unmodified Fourier transform ion cyclotron resonance (FTICR) mass spectrometer by more than an order of magnitude is presented. Commercially available FTICR instruments are usually equipped with a filament‐based electron source producing an electron beam that has a rather small cross section. An ideal overlap between the rotating ion cloud and the electron beam appears to be a prerequisite for a high ECD efficiency. A reduced interception of the ion cloud and the electron beam is probably due to the contribution of the magnetron motion to the trajectory of the ions, resulting in a precession about the z‐axis of the instrument. By increasing the kinetic energy and therefore increasing the cyclotron radii of the precursor ions by resonant excitation, the overlap of the rotating ion cloud with the electron beam is improved. By use of this protocol the efficiency of electron capture is substantially increased and consequently the acquisition time of ECD spectra is reduced significantly. The capability of resonant excitation of the precursor ions during the irradiation with electrons is demonstrated for standard peptides. This approach is particularly valuable for analysis and characterization of O‐glycosylated peptides. In addition to amino acid sequence information, the attachment site of the labile glycan moiety is determined, and also radical‐site‐induced fragmentations of the glycosidic bonds are observed. Copyright © 2003 John Wiley & Sons, Ltd.
Probing cell chemistry with time‐of‐flight secondary ion mass spectrometry: development and exploitation of instrumentation for studies of frozen‐hydrated biological material
Authors: Cliff Ben , Lockyer Nicholas , Jungnickel Harald , Stephens Gill , Vickerman John C.
Published: January 2005

Imaging static secondary ion mass spectrometry (SIMS) offers a powerful method of obtaining molecular information from biological systems with good spatial resolution. However, the technique needs further development to make it suitable for routine analysis of cells. We report here the development of a new freeze‐facture device to facilitate the manipulation and analysis of biological cell material, with the cell chemistry preserved intact by rapid freezing. We illustrate performance characteristics with high‐contrast images of freeze‐fractured, frozen‐hydrated liposomes with the drug clofazamine constrained within the lipid bilayer providing a marker to determine the fracture plane across the liposome structure. By monitoring and imaging clofazamine on the surface of yeast cells in the frozen‐hydrated state, and demonstrating its absence within molecular information from a cell fractured to reveal the cell ultrastructure, we demonstrate that the molecule does not penetrate the cell wall. Copyright © 2003 John Wiley & Sons, Ltd.
Targeted lipidomics using electron capture atmospheric pressure chemical ionization mass spectrometry
Authors: Lee Seon Hwa , Williams Michelle V. , DuBois Raymond N. , Blair Ian A.
Published: January 2005

There is an increasing need to be able to conduct quantitative lipidomics analyses as a complement to proteomics studies. The highest specificity for proteomics analysis can be obtained using methodology based on electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) coupled with liquid chromatography/tandem mass spectrometry (LC/MS/MS). For lipidomics analysis it is often necessary to be able to separate enantiomers and regioisomers. This can be very challenging when using methodology based on conventional reversed‐phase chromatography. Normal‐phase chromatography using chiral columns can provide dramatic improvements in the resolution of enantiomers and regioisomers. However, conventional ESI‐ and APCI‐MS/MS has limited sensitivity, which makes it difficult to conduct studies in cell culture systems where only trace amounts of non‐esterified bioactive lipids are present. The use of electron capture APCI‐MS/MS overcomes this problem. Enantiomers and regioisomers of diverse bioactive lipids can be quantified using stable isotope dilution methodology coupled with normal‐phase chiral chromatography and electron capture APCI‐MS/MS. This methodology has allowed a lipidomics profile from rat epithelial cells maintained in culture to be delineated and allowed the effect of a non‐selective lipoxygenase inhibitor to be assessed. Copyright © 2003 John Wiley & Sons, Ltd.
Fast liquid chromatography coupled to electrospray tandem mass spectrometry peptide sequencing for cross‐species protein identification
Authors: Witters Erwin , Laukens Kris , Deckers Peter , Dongen Walter Van , Esmans Eddy , Onckelen Harry Van
Published: January 2005

Using a parallel microcolumn switching liquid chromatography set‐up coupled to a quadrupole time‐of‐flight mass spectrometer, a rapid liquid chromatography/mass spectrometric (LC/MS) protein identification method is presented. Without prior sample clean‐up up to 300 protein digest samples a day can be processed. Using data‐directed acquisition, up to 10 fragmentation analyses for each protein sample can be acquired in the same chromatographic run that can be used for database searching. Using internal peptide sequence information, protein databases and the various nucleic acid databases can both be queried for cross‐species identification of the protein sample. The method was evaluated and put into force to generate data for a tobacco cell culture protein database. Copyright © 2003 John Wiley & Sons, Ltd.
Matrix‐assisted laser desorption/ionization analysis of lipids and high molecular weight hydrocarbons with lithium 2,5‐dihydroxybenzoate matrix
Authors: Cvačka Josef , Svatoš Aleš
Published: January 2005

Lithium 2,5‐dihydroxybenzoate (LiDHB) is shown to be a very effective matrix for matrix‐assisted laser desorption/ionization (MALDI) analysis of nonpolar long‐chain lipids, hydrocarbons and polymers. Under standard desorption and ionization conditions using a conventional nitrogen UV laser (337 nm), hydrocarbons (C24–C40), diverse lipids (triglycerides, diglycerides, wax esters from leaves) and saturated polymers are effectively lithiated providing [M+Li]+ ions. The formation of lithiated hydrocarbons is not accompanied by an elimination of hydrogen or other fragmentation reactions and, due to the relatively simple isotopic distribution of lithium, seems to be more useable for analysis of hydrocarbon mixtures than the previously used silver cationization agents. The mass calibration can be conveniently performed either externally or internally using poly(ethylene glycol) commercial standards. Copyright © 2003 John Wiley & Sons, Ltd.