bluuebunny/crossref_metadata_2025 huggingface dataset:
Conformational screening of oligonucleotides by variable‐temperature high performance liquid chromatography: Dissecting the duplex–hairpin–coil equilibria of d(CGCGAATTCGCG)
Authors: Braunlin William H. , Giri Indrajit , Beadling Les , Breslauer Kenneth J.
Published: April 2004

This study probes the potential of variable‐temperature high performance liquid chromatography (VT‐HPLC) as a tool for dissecting and modulating nucleic acid structural transitions, using as a model the duplex–hairpin–coil transitions of d(CGCGAATTCGCG). It is demonstrated that VT‐HPLC, combined with diode‐array detection of the uv signal, enables, for the first time, a physical separation of spectroscopically distinct species that can be assigned to the duplex, hairpin, and coil forms of d(CGCGAATTCGCG). Although the species are spectroscopically distinguishable, they are not readily isolated. Hence, if fractions from the peaks for hairpin or duplex forms are collected and subsequently reinjected onto the cartridge, reequilibration occurs, and both hairpin and duplex peaks are observed. Area integration of the peaks corresponding to duplex and hairpin species provides a means to monitor the duplex to hairpin transition at effective concentrations in the nanomolar range, well below that accessible by conventional spectrophotometers. Concentration‐dependent equilibrium constants, melting temperatures, and standard state enthalpies extracted from our measurements compare very well with previous literature results, and with our own results that take into account the effect of our solvent conditions [100 mM TEAA (triethylammonium acetate) and variable acetonitrile] on the melting behavior. By combining precise temperature control with separation based on size, physical behavior, and interaction free energies, VT‐HPLC provides a powerful tool for both the modulation and the separation of nucleic acid conformations. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Synthesis of Encoded Modified Oligonucleotide Libraries. Part 1
Authors: Sacca Paula A. , Fontana Angelo , Montserrat Javier M. , Iribarren Adolfo M.
Published: April 2004

The basis for further development of combinatorial libraries of modified oligonucleotides tagged by a codifying sequence is discussed. The chemistry involved in the orthogonal synthesis of both strands and some representative examples of building blocks are presented.
Selective Circular Oligonucleotide Probes Improve Detection of Point Mutations in DNA
Authors: Tennilä Tuula , Ketomäki Kaisa , Penttinen Piia , Tengvall Unni , Azhayeva Elena , Auriola Seppo , Lönnberg Harri , Azhayev Alex
Published: April 2004

The synthesis of disulfide‐cross‐linked circular oligonucleotides, employing two different approaches, was accomplished. Several circular oligomers, which bear a C(5)‐aminoalkyl‐tethered thymidine unit, were labeled with photoluminescent europium(III) chelates. All circular structures were thoroughly characterized with denaturing PAGE and electrospray‐ionization mass spectrometry. It was demonstrated that the disulfide cross‐linking, resulting in circularization, considerably increases the enzymatic stability of phosphodiester oligonucleotides. In addition, UV melting experiments, followed, where possible, by extraction of thermodynamic parameters, revealed that several circular oligomers appear to be more selective towards their complementary targets than their corresponding linear precursors. Finally, the mixed‐phase hybridization experiments have demonstrated that use of circular probes indeed improves the selectivity in the detection of DNA point mutations.
First Observation by Fluorescence Polarization of Complexation between mRNA and the Natural Polysaccharide Schizophyllan
Authors: Karinaga Ryouji , Mizu Masami , Koumoto Kazuya , Anada Takahisa , Shinkai Seiji , Kimura Taro , Sakurai Kazuo
Published: April 2004

Schizophyllan is a natural β‐(1→3)‐D‐glucan that exists as a triple helix in H2O and as a single chain in dimethylsulfoxide (DMSO) or basic solution (pH >13). As we have already reported, when a homo‐polynucleotide (e.g., poly(dA), poly(A), or poly(C)) is added to a schizophyllan/DMSO solution, and, subsequently, DMSO is exchanged for H2O, the single chain of schizophyllan forms a complex with the polynucleotide. Since eukaryotic mRNAs have poly(A) tails, we hypothesized that schizophyllan can bind to mRNA by interacting with this tail. However, we have not yet observed complexation between schizophyllan and mRNA after exchanging DMSO for H2O. In this report, we show that the complexation can be accelerated when the solution pH is changed from 13 to 7–8 in the presence of schizophyllan and polynucleotides. By this approach, we found that schizophyllan forms a complex with a yeast mRNA.
Micromonosporin A, a Novel 24‐Membered Polyene Lactam Macrolide from Micromonospora sp. Isolated from Peat Swamp Forest
Authors: Thawai Chitti , Kittakoop Prasat , Tanasupawat Somboon , Suwanborirux Khanit , Sriklung Kanlayanee , Thebtaranonth Yodhathai
Published: April 2004

A novel 24‐membered polyene lactam macrolide, micromonosporin A (=(3E,5E,7Z,15E,17E,19E,21E)‐9,11,13‐trihydroxy‐14,19,24‐trimethyl‐1‐azacyclotetracosa‐3,5,7,15,17,19,21‐heptaen‐2‐one; 1) was isolated from the actinomycete, Micromonospora sp. strain TT1‐11, which was isolated from a very acidic peat swamp forest.
In vivo evidence suggesting a role for purine‐catabolizing enzymes in the pathogenesis of cisplatin‐induced nephrotoxicity in rats and effect of erdosteine against this toxicity
Authors: Söğüt Sadık , Kotuk Mahir , Yılmaz H. Ramazan , Ulu Ramazan , Özyurt Hüseyin , Yıldırım Zeki
Published: April 2004

The aim of this experimental study was to investigate the possible role of adenosine deaminase (AD) and xanthine oxidase (XO) in the pathogenesis of cisplatin‐induced nephrotoxicity and the effect of erdosteine in decreasing the toxicity. The intraperitoneal injection of cisplatin (7 mg kg−1 body weight) induced a significant increase in plasma creatinine level and blood urea nitrogen (BUN), and plasma and damaged renal tissue activities of AD and XO in rats. Co‐treatment with erdosteine (10 mg kg−1day−1) attenuated the increase in the plasma creatinine and BUN levels, and significantly prevented the increase in tissue and plasma AD and XO activities (P<0.05). The results of this study revealed that XO and AD may play an important role in the pathogenesis of cisplatin‐induced nephrotoxicity. The potent free radical scavenger erdosteine may have protective potential in this process and it will become a promising drug in the prevention of this undesired side‐effect of cisplatin, but further studies are needed to illuminate the exact protection mechanism of erdosteine against cisplatin‐induced nephrotoxicity. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of endorphin exposure at weaning on the endorphin and serotonin content of white blood cells and mast cells in adult rat
Authors: Csaba György , Kovács Péter , Pállinger Éva
Published: April 2004

Hormonal imprinting takes place perinatally at the first encounter between the developing receptor and its target hormone, resulting in the accomplishment of normal receptor development. In the presence of an excess of target hormone or the absence of it, or an excess of related molecules which can be bound by the receptor, faulty imprinting develops with life‐long consequences. In previous experiments neonatal endorphin exposure caused a decrease in endorphin and serotonin content of peritoneal mast cells of adult animals. In the present experiment 25‐day‐old (weaned) female rats received 2 μg endorphin, and the endorphin as well as serotonin content of adult mast cells and white blood cells was studied by flow cytometry and confocal microscopy. Peritoneal lymphocytes and blood monocytes contained significantly (p<0.01) less endorphin and peritoneal mast cells less serotonin (p<0.07, i.e. of questionable significance) than the untreated control. The results bring attention to the possibility of durable imprinting of differentiating cells later in life and to the durable (possibly life‐long) effect of an endorphin excess (perhaps caused by injury) manifested in the change of endorphin and serotonin content of immune cells. Copyright © 2004 John Wiley & Sons, Ltd.
Prolonged effect of an H1‐receptor blocker antihistamine on the histamine content of white blood cells and mast cells
Authors: Csaba G. , Kovács P. , Pállinger Éva
Published: April 2004

Hormonal imprinting usually takes place perinatally at the first encounter between the developing receptor and its target hormone, determining the future binding capacity of the receptor for life. Molecules similar to a hormone can cause faulty imprinting also with life‐long consequences. Hormone production of the imprinted cell is also durably influenced. In cytogenic organs imprinting can also be provoked in adulthood. At present the effect of a single terfenadine treatment in adult rats on the histamine content of peritoneal cells (lymphocytes, mast cells and the monocyte–macrophage–granulocyte group), white blood cells (lymphocytes, granulocytes, monocytes) and thymic lymphocytes was studied 3 weeks after treatment to clarify the effect of prolonged treatment with an antihistamine in adulthood.The cells were studied by flow cytometric analysis. Peritoneal mast cells contained significantly more and thymic lymphocytes significantly less histamine than controls. In the other cells the differences were not significant. The results support earlier observations on the effect of antihistamines on mast cell histamine release (inhibition) and call attention to the fact that this effect is durable (hormonal imprinting provoked in adults). Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis of 2,4‐Diaryl‐3,4‐dihydro‐2H‐naphth[2,1‐e][1,3]oxazines and Study of the Effects of the Substituents on Their Ring‐Chain Tautomerism
Authors: Szatmári István , Martinek Tamás A. , Lázár László , Fülöp Ferenc
Published: April 2004

A number of 2‐(α‐amino‐Y‐substituted‐benzyl)‐1‐naphthol hydrochlorides were prepared by a convenient Mannich‐type aminoalkylation. 2,4‐Diaryl‐3,4‐dihydro‐2H‐naphth[2,1‐e][1,3]oxazines were prepared through the ring‐closure reactions of the starting aminonaphthols with aromatic aldehydes, which proved to furnish three‐component (ring1−open−ring2) tautomeric mixtures in CDCl3 at 300 K. The electronic effects of the 2‐aryl groups on the ratios of the ring‐chain tautomeric forms at equilibrium could be described by Equation (1). Study of the effects of substituents X and Y on the tautomeric equilibria [by the aid of the multiple linear regression analysis of Equations (2) and (3)] revealed that the trans‐chain equilibrium constants are significantly influenced by the inductive effect (σF) of substituent Y on the 4‐phenyl ring. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Electronic Effects in Olefin Oxidation by Imidoosmium(VIII) Compounds
Authors: Muñiz Kilian
Published: April 2004

Imido osmium(VIII) complexes are versatile oxidants for C−C double bond functionalisation. Despite their structural similarity with OsO4 their reactivity cannot always be compared with this seminal reagent. Detailed investigations including kinetic competition experiments are presented that uncover the electronic and steric preferences of osmium imido complexes. The different behaviour of OsO4 and its imido derivatives towards tertiary amines and diamines is clarified. Hammett correlation studies reveal that the reactivity spectrum of the respective oxidants ranges from a strongly electrophilic behaviour in the case of OsO4 to a rather nucleophilic character as encountered for OsO(NtBu)3. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A New and Convenient Route to Optically Active 2‐Phosphoryl‐3‐oxo‐5‐alkyl/‐aryltetrahydrofurans and Their Reactions
Authors: Xu Chengfu , Zhang Yonghui , Yuan Chengye
Published: April 2004

The two enantiomers of 4‐hydroxy‐2‐oxo‐4‐alkyl/‐arylalkylphosphonates were prepared chemoenzymatically and converted to chiral 2‐phosphoryl‐3‐oxo‐5‐alkyl/‐aryl tetrahydrofurans using an intramolecular O−H insertion reaction catalyzed by rhodium(II) acetate. The potential biological activity of the resulting tetrahydrofurans is of much interest. The presence of the β‐ketophosphonate skeleton in these heterocycles allowed their use as substrate in the cyclic Horner−Wadsworth−Emmons reaction with aldehydes or ketones furnishing chiral α,β‐unsaturated ketones − a new class of building block in organic synthesis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Structure Elucidation of the Highly Heterogeneous Lipid A from the Lipopolysaccharide of the Gram‐Negative Extremophile Bacterium Halomonas Magadiensis Strain 21 M1
Authors: Silipo Alba , Sturiale Luisa , Garozzo Domenico , Castro Cristina de , Lanzetta Rosa , Parrilli Michelangelo , Grant William D. , Molinaro Antonio
Published: April 2004

Halomonas magadiensis (formerly named Halomonas magadii) is a Gram‐negative extremophilic and alkaliphilic bacterium isolated from Lake Magadi, which is located in the East African Rift Valley. Several members of the halomonad group of bacteria have been shown to inhabit the alkaline brines, including a new member, Halomonas magadiensis strain 21 M1 (NCIMB 13595), an organism that grows at high pH and relatively high salt concentration. The unusual structure of the lipid A family derived from the lipopolysaccharide of Halomonas magadiensis is reported herein. The structure was determined using chemical analysis, NMR spectroscopy and MALDI‐TOF mass spectrometry. Lipid A was also analysed after either de‐O‐acylation or dephosphorylation. The resultant mixture was very heterogeneous in fatty acid substitution, from heptaacyl to triacyl species. The various lipid A molecules obtained by the removal of one or more acyl substituents from the heptaacyl species are described below. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Angiogenesis and skin carcinomas with skull base invasion: a case–control study
Authors: Cernea Claudio R. , Ferraz Alberto R. , de Castro Inês V. , Sotto Miriam N. , Logullo Ângela F. , Bacchi Carlos E. , Potenza André S.
Published: April 2004

Background.

Some skin carcinomas may be very aggressive. Intensity of angiogenesis, measured by intratumoral vessel density using expression of CD34, has been associated with tumor aggressiveness. In this study, the expression of CD34 in basal cell carcinomas ( BCCs) and squamous cell carcinomas (SCCs) with skull base invasion was compared with that in tumors with good outcome.

Methods.

Expression of CD34 was graded as mild, moderate, and intense, in 24 BCCs and 11 SCCs with skull base invasion. The control group included 23 BCCs and 10 SCCs.

Results.

Intense expression of CD34 was noted in 25.00% of BCCs with skull base invasion, compared with 4.35% in the control group (p = .058). Regarding SCCs, intense expression of CD34 was found in 54.55% of aggressive tumors, compared with 10.00% in the control group (p = .133).

Conclusions.

A trend toward denser microvascular angiogenesis was observed in both BCCs and SCCs with skull base invasion compared with less aggressive controls. © 2004 Wiley Periodicals, Inc. Head Neck 26: 396–400, 2004
{2, 3}‐perfect m‐cycle systems are equationally defined for m = 5, 7, 8, 9, and 11 only
Authors: Marzi E. M. Li , Lindner C. C. , Rania F. , Wilson R. M.
Published: April 2004

An m‐cycle system (S,C) of order n is said to be {2,3}‐perfect provided each pair of vertices is connected by a path of length 2 in an m‐cycle of C and a path of length 3 in an m‐cycle of C. The class of {2,3}‐perfect m‐cycle systems is said to be equationally defined provided, there exists a variety of quasigroups V with the property that a finite quasigroup (Q, $\circ$, \, /) belongs to V if and only if its multiplicative (Q, $\circ$) part can be constructed from a {2,3}‐perfect m‐cycle system using the 2‐construction (a $\circ$ a = a for all a ∈ Q and if a ≠ b, a $\circ$ b = c and b $\circ$ a = d if and only if the m‐cycle (…, d, x, a, b, y, c, …) ∈ C). The object of this paper is to show that the class of {2,3}‐perfect m‐cycle systems cannot be equationally defined for all m ≥ 10, m ≠ 11. This combined with previous results shows that {2, 3}‐perfect m‐cycle systems are equationally defined for m = 5, 7, 8, 9, and 11 only. © 2004 Wiley Periodicals, Inc.
Functional characterization of Cx43 based gap junctions during spermatogenesis
Authors: Decrouy X. , Gasc J.‐M. , Pointis G. , Segretain D.
Published: April 2004

In the testis, spermatogenesis is a highly regulated process that includes germ cell multiplication and differentiation supported by Sertoli cells. Gap junction intercellular communication (GJIC), that is known to play an important role in the control of cell proliferation and differentiation, allows communication between adjacent cells. Gap junctions are present within the seminiferous epithelium but the precise nature of coupled cells is not yet identified. By applying a dye‐transfer assay to testis, we demonstrated that coupling was basally located in the tubular compartment between adjacent Sertoli cells, between Sertoli cells and spermatogonia and early and late spermatocytes, but not between Sertoli cells and spermatids. Furthermore, no dye transfer occurred from germ cells to Sertoli cells. Specificity of the gap junction coupling was verified with known gap junction inhibitors such as oleamide, heptanol, and glycyrrhetinic acid. We developed a sophisticated assay that allows correlating the in vivo dye transfer with cell morphological identification and Cx43 expression. This approach demonstrated the Cx43 participation in the coupling. Interestingly Cx43 expression and dye‐coupling varied with the stages of spermatogenesis. Our results suggest that Cx43 based gap junctions form a transversal and longitudinal intercellular communication network within seminiferous tubules, and that specific communication territories are formed within the seminiferous tubules to ensure the synchronization of germ cell proliferation and differentiation. © 2003 Wiley‐Liss, Inc.
Site‐matched papillary and reticular human dermal fibroblasts differ in their release of specific growth factors/cytokines and in their interaction with keratinocytes
Authors: Sorrell J. Michael , Baber M.A. , Caplan A.I.
Published: April 2004

The interfollicular dermis of adult human skin is partitioned into histologically and physiologically distinct papillary and reticular zones. Each of these zones contains a unique population of fibroblasts that differ in respect to their proliferation kinetics, rates at which they contract type I collagen gels, and in their relative production of decorin and versican. Here, site‐matched papillary and reticular dermal fibroblasts couples were compared to determine whether each population interacted with keratinocytes in an equivalent or different manner. Papillary and reticular fibroblasts grown in monolayer culture differed significantly from each other in their release of keratinocyte growth factor (KGF) and granulocyte‐macrophage colony stimulating factor (GM‐CSF) into culture medium. Some matched fibroblast couples also differed in their constitutive release of interleukin‐6 (IL‐6). Papillary fibroblasts produced a higher ratio of GM‐CSF to KGF than did corresponding reticular fibroblasts. Interactions between site‐matched papillary and reticular couples were also assayed in a three‐dimensional culture system where fibroblasts and keratinocytes were randomly mixed, incorporated into type I collagen gels, and allowed to sort. Keratinocytes formed distinctive cellular masses in which the keratinocytes were organized such that the exterior most layer of cells exhibited characteristics of basal keratinocytes and the interior most cells exhibited characteristics of terminally differentiated keratinocytes. In the presence of papillary dermal fibroblasts, keratinocyte masses were highly symmetrical and cells expressed all levels of differentiation markers. In contrast, keratinocyte masses that formed in the presence of reticular fibroblasts tended to have irregular shapes, and terminal differentiation was suppressed. Furthermore, basement membrane formation was retarded in the presence of reticular cells. These studies indicate that site‐matched papillary and reticular dermal fibroblasts qualitatively differ in their support of epidermal cells, with papillary cells interacting more effectively than corresponding reticular cells. © 2003 Wiley‐Liss, Inc.
Molecular tools for a molecular medicine: analyzing genes, transcripts and proteins using padlock and proximity probes
Authors: Landegren Ulf , Schallmeiner Edith , Nilsson Mats , Fredriksson Simon , Banér Johan , Gullberg Mats , Jarvius Jonas , Gustafsdottir Sigrun , Dahl Fredrik , Söderberg Ola , Ericsson Olle , Stenberg Johan
Published: April 2004

Procedures and reagents are needed to specifically detect all the macromolecules that are being identified in the course of genome projects. We discuss how this challenge may be met using a set of ligation‐based reagents termed padlock probes and proximity ligation probes. These probes include elements with affinity for specific nucleic acid and protein molecules, respectively, along with unique identifier DNA sequence elements that encode the identity of the recognized target molecules. The information content of DNA strands that form in the detection reactions are recorded after amplification, allowing the recognized target molecules to be identified. The procedures permit highly specific solution‐phase or localized analyses of large sets of target molecules as required in future molecular analyses. Copyright © 2004 John Wiley & Sons, Ltd.
Unique interaction of scorpion toxins with the hERG channel
Authors: Korolkova Yuliya V. , Tseng Gea‐Ny , Grishin Eugene V.
Published: April 2004

ERG potassium channels specify one component of the delayed rectifier in the heart and are likely to play an important functional role in other excitable cells. Compared to other K+ channels, the human ERG (hERG) channel possesses an unusually long S5‐P linker that presumably forms an alpha‐helix important for channel function. hERG‐specific toxins bind to the outer mouth of the hERG channel. Channel residues in the middle of the S5‐P linker and at the pore entrance are critical for toxin binding. One of these scorpion toxins is BeKm‐1. Residues critical for BeKm‐1 binding to the hERG channel are located in the alpha‐helix and the following loop, whereas the ‘traditional’ interaction surface of other short scorpion toxins is formed by residues on the β‐sheet. This unique localization of BeKm‐1's interaction surface and its specific action on the hERG channel suggest a unique outer mouth structure of the hERG channel. We used the mutant cycle analysis approach to define contacts in the toxin–channel complex. This information provides critical constraints and is important for molecular modeling of the hERG pore structure. Copyright © 2004 John Wiley & Sons, Ltd.
Proteins, recognition networks and developing interfaces for macromolecular biosensing
Authors: Sergi Mauro , Zurawski John , Cocklin Simon , Chaiken Irwin
Published: April 2004

Genomics and proteomics discovery is leading to the identification of all proteins and to the opportunity, and challenge, to reveal the protein recognition networks that drive virtually all biological processes. Over the past decade, biosensors have emerged as a key technology for detection and analysis of biomolecular interactions. An important limitation in developing such biosensors is that the focus has been mainly on sensor platforms, the transducing hardware that converts interaction signals into recorded data, without adequately considering the role of molecular interfaces, the elements of sensors that interact with analytes to produce signals. We have investigated this alternative focus by identifying and, where necessary, designing molecular interfaces that will more effectively drive new biosensor development and utilization in biomedical and biotechnological investigations. Here we describe our recent studies of coiled coil and lipid bilayer interfaces and the potential to use these to expand sensing technologies for multiplexed target detection and analysis in increasingly biologically relevant membrane like environments. Copyright © 2004 John Wiley & Sons, Ltd.
On‐chip single‐cell‐based microcultivation method for analysis of genetic information and epigenetic correlation of cells
Authors: Yasuda Kenji
Published: April 2004

We have developed an on‐chip single‐cell based microcultivation method for analyzing the variability of genetic information stored in single cells and their epigenetic correlations. The method uses four systems: an on‐chip cell sorter for purifying the cells in a non‐destructive manner; an on‐chip single‐cell cultivation chip for isolating single cells; an on‐chip agarose microchamber system for constructive cell‐cell network formation during cultivation; and an on‐chip single‐cell‐based expression analysis system. Using these systems, we could measure the variability of prokaryotic cells and eukaryotic cells having the same DNA and found that, although prokaryotic cells have a large variability in their interdivision times, sister eukaryotic cells having the same DNA synchronized well. We also measured the dynamics of synchronization of beating cardiac myocytes and found that two isolated cells synchronize by one cell following the other after a short pause in beating. These results showed the potential of the on‐chip microcultivation method's constructive approach to analyzing cell systems. Copyright © 2004 John Wiley & Sons, Ltd.
Supramolecular architectures featuring stereoisomeric cluster complexes of the [Re6(μ3‐Se)8]2+ core
Authors: Selby Hugh D. , Roland Bryan K. , Cole Jenine R. , Zheng Zhiping
Published: April 2004

The [Re6(μ3‐Se)8]2+ core‐containing cluster complexes of the general formula [Re6(μ3‐Se)8(PEt3)4L2]2+ (both trans‐ and cis‐isomers) site‐differentiated with inert PEt3 and functional L ligands that are capable of hydrogen bonding or secondary (with respect to primary coordination with the cluster core) metal‐ligand coordination interactions have been prepared. The applications of such stereospecific cluster isomers as building blocks for supramolecular construction have been studied. A great variety of multicluster arrays mediated by intercluster hydrogen bonding or cluster ligand coordination with secondary metal ions have been obtained and structurally characterized. The findings from this research clearly establish the superior utility of these novel building blocks for the creation of structurally sophisticated architectures and possibly functional materials.
Novel carbazole dendrimers having a metal coordination site as a unique hole‐transport material
Authors: Kimoto Atsushi , Cho Jun‐Sang , Higuchi Masayoshi , Yamamoto Kimihisa
Published: April 2004

We have synthesized novel carbazole dendrimers via the cyclotrimerization of aminophenylketones in the presence of titanium tetrachloride. These dendrimers have the ability to assemble metal ions such as Sn2+ and Eu3+ with no significant difference in their generation, suggesting the dendrimer with an interior with a small density up to the third generation. We show the dendrimers with higher generations have the higher HOMO values. The most electron rich molecule, the G3 dendrimer, has the highest HOMO value of −5.2 eV. However, for the HOMO energy levels of the carbazole dendrimer complex with Eu(OTf)3, the energy levels of the carbazoles did not change based on almost the same redox potentials as those of the dendrimers, themselves. Using the carbazole dendrimers and their europium complex, a homogeneous film was produced, which enhanced the performance of the electroluminescence device in comparison with only the dendrimer as the hole‐transporting layer. This approach was managed by a solution process, i.e., the spin‐coating method, without using the coevaporation technique based on the large equilibrium constants of the coordination of metal ions on the imine sites (K = 105 M−1).
Luminescence properties of organometallic/coordination oligomers and polymers containing diphosphine and diisocyanide assembling ligands: comparison between mononuclear model complexes and polymers
Authors: Harvey Pierre D.
Published: April 2004

This paper describes the luminescence properties of selected examples of homo‐ and mixed‐bridging ligand‐containing organometallic/coordination oligomers and polymers of copper(I), silver(I), palladium(I) and −(0.5), and platinum(0.5). The bridging ligands are the 1,8‐diisocyano‐p‐menthane (dmb) and bis(diphenylphosphino)methane (dppm), ‐ethane (dppe), ‐propane (dppp), ‐butane (dppb), ‐pentane (dpppen), and −hexane (dpph), as well as bis(diphenyl‐phosphino)acetylene (dpa) and bis(dimethylphosphino)methane (dmpm). The comparison between the mononuclear model complexes and the polymers of the emission maxima (λmax) and emission lifetimes (τe) will be made, and interpreted by the presence of intrachain interactions and exciton phenomena.
Metallodendritic materials for heterogenized homogeneous catalysis
Authors: Bourrier Olivier , Kakkar Ashok K.
Published: April 2004

Design of supports containing a hyperbranched backbone and active transition metal centers at the periphery is described. Such nanoarchitectures can be easily assembled from 3,5‐dihydroxybenzyl alcohol and dimethylsilylamine using a divergent synthetic methodology. Following a controlled reaction pathway, construction of dendrimers of up to generation 5 is achieved, while a simple mix of reagents in one‐pot or with sequential additions yields analogous hyperbranched polymers. Subsequent functionalization at the periphery with phosphine followed by Rh(I) centers yields the desired metallodendritic materials. The efficiency of the latter in catalytic hydrogenation of decene under varied conditions is surveyed.
Ring‐opening polymerisation of coordination rings and cages
Authors: James Stuart L.
Published: April 2004

Despite the great interest in crystalline coordination polymers (sometimes called metal organic frameworks) surprisingly little is known about how they form. However, there has recently been some attention given to characterising their solution‐based precursors. Of particular interest is the formal ring‐opening polymerisation (ROP) relationship between the structures of some precursors and polymers, and the actual observation of ring‐opened oligomers by solution state NMR spectroscopy. These points are highlighted and discussed along with related aspects of isomerism in discrete and polymeric coordination structures, and polymer‐polymer interconversion.
Synthesis of sulfone‐containing monomers and polymers using cationic cyclopentadienyliron complexes
Authors: Abd‐El‐Aziz Alaa S. , Pereira Nelson M. , Boraie Waleed , McFarlane Shaune L. , Todd Erin K.
Published: April 2004

The synthesis of sulfone‐containing monomers with pendent cationic cyclopentadienyliron (CpFe+) moieties has been accomplished via nucleophilic aromatic substitution of dichloroarene complexes with a number aliphatic dithiols. These complexes were further oxidized using m‐CPBA to give the sulfone‐based monomers. Polymerization of the sulfone‐based monomers with O‐containing nucleophiles produced the sulfone‐based polymers. Direct nucleophilic aromatic substitution of dichloroarene complexes with dinucleophiles allowed for the formation of organoiron sulfide‐based polymers. Oxidation of these polymers led to the formation of sulfone polymers with the pendent iron moieties. The organometallic monomers and polymers were found to be more soluble in polar solvents in comparison to their organic analogues.
Investigation of spatial inhomogeneities of the thermal properties of a NiTi shape memory alloy device
Authors: Gibkes J. , Siegert W. , Bein B.K. , Pelzl J.
Published: April 2004

Local changes of the phase transition on a SM one‐way actuator have been investigated by time‐dependent IR thermography and compared with the local behavior of thermal properties studied by means of scanning thermal microscopy and modulated IR radiometry at room temperature and at 120 °C. The results point towards large spatial inhomogeneities of the shape memory properties developing with increasing temperature and which are the reason that only parts of the material transform into the austenite phase.
High‐Temperature Corrosion of NiTi‐Shape‐Memory Alloys
Authors: Heßing C. , Gabert S. , Pohl M. , Parezanović I.
Published: April 2004

Semi‐finished products and components made of NiTi‐shape‐memory alloys (NiTi‐SMA) are often subjected to heat treatment after their fabrication. During this heat treatment, oxide layers begin to form which contain a high amount of titanium.

In this investigation special attention was drawn to the selective oxidation of Ti because a TiOX‐layer can represent a Ni‐barrier and may therefore be of special use for medical applications. A comparison of the following three samples was carried out: A sample oxidised at room temperature, another that was heat‐treated in ambient air (600 °C/1min) and a third sample that was subjected to a heat treatment (600 °C/1min) in an atmosphere that oxidises titanium but reduces NiO in order to achieve a selective oxidation of the titanium. The analysis of the oxide layers was carried out by means of x‐ray photoelectron spectroscopy (XPS). It was shown that the ratio of titanium to nickel in the oxide layer can be substantially increased when performing the annealing treatments in a partial reducing atmosphere.

Furthermore, a thermo‐gravimetric investigation of the material was carried out at 600 °C in dry air in order to estimate the growth of the oxide layers.
Alternating current scanning electrochemical microscopy (AC‐SECM) studies on the surface of electrochemically polished NiTi shape memory alloys
Authors: Belger S. , Schulte A. , Hessing C. , Pohl M. , Schuhmann W.
Published: April 2004

Aiming at imaging local differences in electrochemical activity and related corrosion effects, the surface of electropolished NiTi was investigated using alternating current scanning electrochemical microscopy (AC‐SECM). Segregation‐related spatial variations in the rates of the anodic dissolution that are responsible for the formation of wavy surfaces during electropolishing could not be identified with AC‐SECM. Instead, the surface appeared rather uniform and did not reflect any (patterned) corrosion activity. Obviously, the anodically grown oxide film is highly isolating and passivating. This rationalizes the absence of the evolution of surface irregularities at the solid/liquid interface of NiTi‐shape‐memory alloys.
Porous Metal Sheets of NiTi made by Wet Powder Spraying
Authors: Schüller E. , Krone L. , Bram M. , Buchkremer H. P. , Stöver D.
Published: April 2004

As a promising method to produce thin porous NiTi sheets, Wet Powder Spraying (WPS) is applied for NiTi powders. Layers with a thickness of 150 μm are obtained from pre‐alloyed NiTi powders with a particle size of < 12 μm. Optimized process control for spraying and sintering was used. Microstructure and phase formation is characterized. The sheets with a porosity of 15 % show a high pseudoelastic flexibility at room temperature. Phase transformation temperatures are determined by Differential scanning calorimetry (DSC). The one way effect could be demonstrated.
NiTi shape memory alloys coated with calcium phosphate by plasma‐spraying. Chemical and biological properties
Authors: Prymak O. , Bogdansk D. , Esenwein S.A. , Köller M. , Epple M.
Published: April 2004

Plates of superelastic nickel‐titanium shape memory alloy (NiTi) were coated with calcium phosphate (hydroxyapatite) by high‐temperature plasma‐spraying. The porous layer of about 100 μm thickness showed a good adhesion to the metallic substrate that withstood bending of the plate but detached upon cutting the plate. The biocompatibility was tested by cultivation of blood cells (whole blood and isolated granulocytes [a subpopulation of blood leukocytes]). As substrates, pure NiTi, plasma‐spray‐coated NiTi and calcium phosphate‐coated NiTi prepared by a dip‐coating process were used. The adhesion of whole blood cells to all materials was not significantly different. In contrast, isolated granulocytes showed an increased adhesion to both calcium phosphate‐coated NiTi samples. However, compared to non‐coated NiTi or dip‐coated NiTi, the number of dead granulocytes adherent to plasma‐sprayed surfaces was significantly increased for isolated granulocytes (p<0.01).
Numerical Modelling of the Activation Behaviour of SMA‐Actuator Wires – Application in an Innovative Drive System
Authors: Meier H. , Oelschläger L.
Published: April 2004

The activation behaviour of Shape‐Memory‐Alloy actuators (SMA) (and more specifically their dynamic properties) is characterised by the rate of heating and cooling. This paper deals with the development, the validation and the application of a numerical model that simulates the activation behaviour of straight SMA‐wires depending on their geometry, the loading condition and an arbitrary time variant heating current. Taking changing thermal, electrical, geometric and mechanical boundary conditions into consideration, the model supports the design layout process of technical solutions with SMA‐wires. Based on this numerical model for dimensioning and conditioning of SMA‐actuators, an innovative rotatory drive system powered by straight SMA‐wires is presented.
A new finite element technology for shape memory alloy composites
Authors: Christ D. , Reese S. , Neuking K.
Published: April 2004

In this paper, we present a computationally efficient implementation of a continuum mechanical model for shape memory alloys into a finite element code. The model covers several thermomechanically coupled effects typical for the material behaviour of shape memory alloys, e.g. pseudo‐elasticity, the one‐way shape memory effect and the two‐way shape memory effect due to external loads. Via the use of a finite element formulation based on only one Gauss point, the computational effort is reduced enormously.
Presentation of Creutzfeldt–Jakob disease as acute corticobasal degeneration syndrome
Authors: Kleiner‐Fisman Galit , Bergeron Catherine , Lang Anthony E.
Published: April 2004

We provide a brief report with videotape documentation of a possible case of Creutzfeldt–Jakob disease. © 2004 Movement Disorder Society
Double‐blind, randomized, controlled trial of rasagiline as monotherapy in early Parkinson's disease patients
Authors: Stern Matthew B. , Marek Kenneth L. , Friedman Joseph , Hauser Robert A. , LeWitt Peter A. , Tarsy Daniel , Olanow C. Warren
Published: April 2004

Rasagiline (N‐propargyl‐1(R)‐aminoindan) mesylate is a potent, selective, and irreversible monoamine oxidase‐B inhibitor. This study was designed to evaluate the safety, tolerability, and preliminary efficacy of rasagiline monotherapy in early Parkinson's disease (PD) patients not receiving levodopa. The study was performed as a multicenter, parallel‐group, double‐blind, randomized, placebo‐controlled, 10‐week study. Fifty‐six PD patients were randomly assigned to rasagiline mesylate 1, 2, or 4 mg once daily, or placebo. A 3‐week dose‐escalation period was followed by a 7‐week maintenance phase. At week 10, the mean (±SE) changes from baseline in total Unified Parkinson's Disease Rating Scale (UPDRS) score were −1.8 (±1.3), −3.6 (±1.7), −3.6 (±1.2), and −0.5 (±0.8) in the rasagiline 1, 2, and 4 mg/day and placebo groups, respectively. Analysis of responders showed that 28% of patients (12 of 43) receiving rasagiline had an improvement in total UPDRS score of greater than 30%, compared with none of the patients receiving placebo (P < 0.05, Fisher's exact test). The frequency and types of adverse events reported by rasagiline‐treated and placebo‐treated patients were similar. These results suggest that rasagiline monotherapy is well tolerated and efficacious in early PD. © 2004 Movement Disorder Society
A note on a secure voting system on a public network
Authors: Karagiannopoulos M. G. , Vrahatis M. N. , Meletiou G. C.
Published: April 2004

This article shows that the procedure proposed in Chang and Wu (1997) and extended in Dini (2001) does not always produce accurate results. A modification that makes the procedure correct is suggested. © 2004 Wiley Periodicals, Inc.
Stress‐ and cell cycle‐associated regulation of RGS2 mRNA levels
Authors: Zmijewski Jaroslaw W. , Song Ling , Jope Richard S.
Published: April 2004

Regulators of G‐protein signaling family members, such as RGS2, are thought to primarily be involved in regulating the activity of second messenger systems by attenuating heterotrimeric G‐protein actions. However, we found previously that RGS2 is predominantly located in the nucleus, not at the plasma membrane where most G‐proteins exist, and that stressful conditions increased RGS2 expression. Here we report that induction of DNA damage‐induced cell cycle arrest with camptothecin caused prolonged increases in RGS2, and decreases in RGS4, mRNA levels. Cell cycle arrest caused by nocodazole also increased RGS2, and decreased RGS4, mRNA levels. Additionally, using synchronization to minimize cell stress, RGS2 mRNA levels were low in G0 and G1, and elevated in the other phases of the cell cycle. These results demonstrate that RGS2 expression is coupled to cellular stress and the cell cycle, and that these conditions cause opposite effects on RGS2 and RGS4 mRNA levels.
Treadmill exercise suppresses NPY expression in the hypothalamus of food‐deprived rats
Authors: Kim Sung‐Soo , Shin Mal‐Soon , Kim Hong , Kim Eun‐Kyung , Lee Hee‐Hyuk , Chang Hyun‐Kyung , Lee Taeck‐Hyun , Jang Mi‐Hyeon , Shin Min‐Chul , Lim Baek‐Vin , Kim Chang‐Ju
Published: April 2004

Exercise has been known to potentially affect food intake. Neuropeptide Y (NPY) is a 36 amino acid peptide and concentrated in the hypothalamus which is an appetite‐regulating area. NPY is known to stimulate appetite and decrease energy expenditure. In the present study, the effect of treadmill running on the NPY expression in the hypothalamus of food‐deprived rats was investigated using immunohistochemistry. Enhanced NPY expression in the paraventricular nucleus (PVN) and arcuate nucleus (ARN) was observed in the food‐deprived rats. Treadmill exercise suppressed the enhancement of NPY expression in the PVN and ARN following food deprivation, but this suppressive effect was not affected by exercise intensity. Based on the present results, it can be suggested that treadmill exercise is effective in limiting the enhancement of NPY expression following food‐deprived conditions.
JC virus genotyping offers a new paradigm in the study of human populations
Authors: Yogo Yoshiaki , Sugimoto Chie , Zheng Huai‐Ying , Ikegaya Hiroshi , Takasaka Tomokazu , Kitamura Tadaichi
Published: April 2004

A small DNA virus, named JC virus (JCV) and belonging to the Polyomaviridae, is attracting the attention of anthropologists worldwide, as JCV genotyping appears to be a novel means of elucidating human migrations and the origins of various ethnic groups. The basic properties of JCV, the regional distributions of JCV genotypes, and the phylogenetic relationships among various JCV genotypes are described. Then, a study is described in which the origin of the modern Japanese was extensively investigated using the JCV genotyping method. Based on JCV genotypes in neighboring areas, the origins of people who carried JCV genotypes to the Japanese Archipelago are discussed. Finally, the relationships between JCV genotypes and Y‐chromosome haplogroups are examined, as genetic variation on the Y chromosome has recently been examined in detail to investigate ancient human migrations and the population structures of human groups. Copyright © 2004 John Wiley & Sons, Ltd.
Combining several ordinal measures in clinical studies
Authors: Wittkowski Knut M. , Lee Edmund , Nussbaum Rachel , Chamian Francesca N. , Krueger James G.
Published: April 2004

In medical research, it is rare that a single variable is sufficient to represent all relevant aspects of epidemiological risk, genomic activity, adverse events, or clinical response. Since biological systems tend to be neither linear, nor hierarchical in nature, the assumptions of traditional multivariate statistical methods based on the linear model can often not be justified on theoretical grounds. Establishing concept validity through empirical validation is not only problematic, but also time consuming. This paper proposes the use of u‐statistics for scoring multivariate ordinal data and a family of simple non‐parametric tests for analysis. The scoring method is demonstrated to be applicable to scoring clinical response profiles in the treatment of psoriasis and then to identifying genomic pathways that best correlate with these profiles. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and Characterization of Cross‐linked Carboxymethyl Potato Starch Ether Gels
Authors: Seidel Christian , Kulicke Werner‐Michael , Heß Christoph , Hartmann Brigitte , Lechner M. Dieter , Lazik Waldemar
Published: April 2004

Hydrogels were synthesized by cross‐linking of potato starch (PS) with dichloroacetic acid (DCA) in the presence of monochloroacetic acid (MCA) to form etherified carboxymethyl starch (CMS) gels, to be used for ultrasonic medical examinations. By etherification cross‐linked CMS‐hydrogels can be produced, that are stable in contrast to the in the long‐term unstable esterified gels, that were presented in the last paper. The rheological benchmarks for the CMS‐hydrogels were set in comparison with synthetic ultrasonic gels. Gels with potato starch contents in the reaction batch ranging from 12.5% to 20% showed the best compliance with the benchmark parameters. The DS values of these CMS‐hydrogels vary from 0.42 to 0.49, increasing with decreasing amount of starch in the reaction mixture. The free swelling capacities (FSC) vary between 77 g/g for the 12.5% PS‐gel and 34 g/g for 20% PS‐gel, the turbidities of the samples being in the range from 14.5 NTU (Nephelometric Turbidity Units) (12.5% PS) up to 20.5 NTU (20% PS). The variation of the PS fraction in the reaction mixture showed that with an increased amount of PS in the reaction batch the number of cross‐links of the CMS‐gels increases, too. At a higher number of cross‐links the swelling capacity is reduced and the concentration needed to form stable hydrogels is greatly increased. Thus a hydrogel of a polymer concentration of 5 mass‐% from a 12.5% PS batch was produced, that showed the best accordance with the rheological benchmark parameters such as gelatinization time, visco‐elastic and pseudoplastic properties and long‐term stability. The ultrasonic pictures taken with this CMS‐gel were not different from those taken with the synthetic gels. This hydrogel was then subjected to long‐term‐stability measurements performed over one year and to rheological temperature cycle tests. The tests showed that the long‐term stability of the gels is sufficient for their use as ultrasonic gel.