bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Crystal Structure of a Cocrystalline Compound of a Rare Earth Metalloporphyrin with Fullerene {[TPPYb(μ‐OH)2Yb(THF)TPP]·C60}n
Authors: Zhang Jie , Cai Ruifang , Chen Minqing , Weng Linhong , Zhou Xigeng
Published: July 2005

The reaction of YbI2(THF)2 with TPPLi2 (TPP = 5,10,15,20‐tetraphenylporphyrin) in THF, and then with 0.5 equiv. of C60, which was solvated in toluene beforehand, gave the title compound {[TPPYb(μ‐OH)2Yb(THF)TPP]·C60}n, which is the first example of a rare earth metallofullerene cocrystal compound. X‐ray structural analyses indicate that this compound displays a complicated supramolecular structure, which contains some unique noncovalent interactionsbetween C60 and the rare earth metalloporphyrin units. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Immunomodulatory α‐Galactoglycosphingolipids: Synthesis of 2'‐Fluoro‐2'‐deoxy‐α‐galactosylceramide and an Evaluation of Its Immunostimulating Properties
Authors: Barbieri Lucia , Costantino Valeria , Fattorusso Ernesto , Mangoni Alfonso , Basilico Nicoletta , Mondani Monica , Taramelli Donatella
Published: July 2005

In the framework of a project to assess the immunomodulating properties of α‐galactosyl glycosphingolipids, the total synthesis of 1‐O‐(2‐fluoro‐2‐deoxy‐α‐D‐galactopyranosyl)‐2‐docosanoylamino‐1,3,4‐octadecanetriol (1), a 2'‐fluoro analogue of the immunostimulating α‐galactoglycosphingolipids, was accomplished. The glycosidation reaction of the azido precursor of sphingosine was performed using the Mukaiyama glycosidation reaction. The stimulation of mouse splenocyte proliferation by the 2'‐fluoro analogue was highly reduced compared to that of the α‐galactoglycosphingolipids, thereby confirming that a free galactose 2‐OH group is essential for the immunostimulatory activity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Regioselectivity of Michael Additions to 3‐(Pyridin‐3‐yl or Pyrimidin‐2‐yl)propenoates and Their N‐Oxides – Experimental and Theoretical Studies
Authors: Lewandowska Elzbieta , Chatfield David C.
Published: July 2005

We demonstrate that nucleophilic addition to α,β‐unsaturated carbonyl compounds can be redirected from the usual β‐carbon (Michael) to an α‐carbon regioselectivity by attaching a π‐deficient aromatic substituent to the β‐carbon atom. In particular, propanethiol addition to 3‐(pyridin‐3‐yl or pyrimidin‐2‐yl)propenoate gives a β‐carbon adduct, while addition to the corresponding more π‐deficient N‐oxides gives the α‐adduct or a mixture of α‐ and β‐adducts. This adds to the number of carbon–carbon bond‐forming reactions at the α‐position of Michael receptors documented recently. Density functional calculations reveal that the regioselectivity is due to a combination of reduction of the barrier for α‐addition and increase of the barriers for β‐addition and carbonyl addition as the π‐deficient character of the aromatic substituent is increased. The calculations predict a significant solvent effect on the regioselectivity in some cases. The regioselectivity is also consistent with Hammett constants σ–. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Stereoselective Synthesis of (E)‐Hydroxystilbenoids by Ruthenium‐Catalyzed Cross‐Metathesis
Authors: Ferré‐Filmon Karine , Delaude Lionel , Demonceau Albert , Noels Alfred F.
Published: July 2005

An efficient and highly stereoselective synthetic procedure is reported for the construction of symmetrical and unsymmetrical (E)‐polymethoxystilbene and (E)‐polyhydroxystilbene derivatives. The strategy rests on a cross‐metathesis reaction catalyzed by stable, well‐defined (alkylidene)ruthenium complexes, in particular the second‐generation Grubbs catalyst [RuCl2(=CHPh)(SIMes)(PCy3)] [SIMes = 1,3‐bis(2,4,6‐trimethylphenyl)imidazolidin‐2‐ylidene]. The metathesis of unprotected phenolic styrenes is illustrated by the synthesis of the important phytoalexins (E)‐3,4',5‐trihydroxystilbene (resveratrol) and (E)‐3,3',4,5'‐tetrahydroxystilbene(piceatannol). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
A DFT Study of the Concerted Cyclisation of 3‐Azidopropenal to Isoxazole:Is it a Pseudopericyclic Reaction According to Its Magnetic Properties?
Authors: Peña‐Gallego Angeles , Rodríguez‐Otero Jesús , Cabaleiro‐Lago Enrique M.
Published: July 2005

A comprehensive B3LYP/6‐31+G(2d,p) study of the nature of the concerted cyclisation of 3‐azidopropenal to isoxazole was conducted. For this purpose, the complete pathway was determined and changes in different magnetic properties [magnetic susceptibility (χ), magnetic susceptibility anisotropy (χanis) and the nucleus‐independent chemical shifts (NICS)] were monitored along the reaction profile with a view to estimating the aromatisation associated with the process. We have also applied the ACID (anisotropy of the current‐induced density) method with the same intention. Analysis of the results in depth indicates a pseudocoarctate character for this reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Isolation of Phlorin‐Dipyrrin Conjugates from the Acid‐Catalyzed Condensation of Dipyrromethanes and Aldehydes
Authors: Gryko Daniel T. , Koszarna Beata
Published: July 2005

The product distribution of the acid‐mediated condensation of dipyrromethanes and aldehydes was studied and a novel type of macrocycle phlorin‐dipyrrin conjugate was isolated and identified by X‐ray analysis. The generality of its formation from sterically hindered dipyrromethanes and pentafluorophenyldipyrromethane was demonstrated. The influence of the meso‐aryl groups on the stability of the phlorin was studied. The reported two‐step synthesis of a phlorin derivative is one of the simplest routes leading to this type of molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Transannular Hydride Migration in Pseudo‐Geminally Substituted [2.2]Paracyclophanes: A Vinylogous Pinacol Rearrangement
Authors: Birsa M. Lucian , Jones Peter G. , Hopf Henning
Published: July 2005

A vinylogous pinacol–pinacolone rearrangement is reported that takes place although the two hydroxyl groups are formally separated by seven bonds. It involves a transannular hydride shift that occurs between the benzylic positions of the pseudo‐geminally substituted [2.2]paracyclophanes 1a–c, 7, 8 and 9. Under mild acidic conditions the corresponding pseudo‐geminally substituted cyclic ethers were established as stable intermediates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
New Insights into the Chemistry of gem‐Bis(phosphonates): Unexpected Rearrangement of Michael‐Type Acceptors
Authors: Szajnman Sergio H. , García Liñares Guadalupe , Moro Pablo , Rodriguez Juan B.
Published: July 2005

The use of tetraethyl ethylidenebis(phosphonate) as a Michael acceptor with different nucleophiles was investigated. It was found that in some cases this compound undergoes phosphate removal, depending on the nature of the nucleophile. The chemical behavior of its epoxy derivative tetraethyl oxiranylidenebis(phosphonate) as an electrophile was also studied. This compound underwent a very attractive and remarkable phosphonate‐phosphate rearrangement resulting in the enol phosphate 8 regardless of the nucleophile employed. Different mechanistic studies were conducted in an attempt to explain the mechanisms involved. To the best of our knowledge, this reaction constitutes a remarkable novelty, being the first reported rearrangement reaction of an epoxy derivative of a gem‐bis(phosphonate). In addition, evidence supporting the involvement of a radical or a polar mechanism, depending on the nature of the nucleophile, is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis and Properties of an Unsymmetrical Triazole‐Functionalized (Phthalocyaninato)zinc Complex
Authors: Vagin Sergej , Frickenschmidt Antje , Kammerer Bernd , Hanack Michael
Published: July 2005

The synthesis of 5,6‐dicyano‐1H‐1,2,3‐benzotriazole (2) was significantly simplified and its overall yield was increased. This opens up the possibility for an extended use of 2 as a precursor for triazole‐functionalized phthalocyanines. One of them, the unsymmetrical {9,10,16,17,23,24‐hexakis(3,5‐di‐tert‐butylphenoxy)[1,2,3]triazolo[4,5‐b]phthalocyaninato}‐zinc (5) was prepared in a statistical condensation of 2 and 4,5‐bis(3,5‐di‐tert‐butylphenoxy)phthalonitrile (3) with subsequent separation by column chromatography. The triazole‐functionalized (phthalocyanine)zinc complex 5 shows interesting spectral properties in solutions depending on the chemical medium because of the reactions which are typical for the triazole fragment. These are acid ionization of NH, coordination to metal ions, N‐alkylation and N‐acylation, among others. Compound 5 was characterized in detail using UV/Vis, 1H and 13C NMR spectroscopy, mass spectrometry (MALDI‐TOF), and elemental analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Preparation of Conformationally Constrained α2 Antagonists:The Bicyclo[3.1.0]hexane Approach
Authors: Bonnaud Bernard , Funes Philippe , Jubault Nathalie , Vacher Bernard
Published: July 2005

The aim of the research was to discover antagonists at α2 receptor subtypes potentially more selective than known compounds. We focused on new, conformationally restricted analogues of atipamezole. The key step in the synthetic sequences leading to target compounds relied on a rhodium‐catalyzed intramolecular cyclopropanation reaction, the outcome of which varied with the nature of the diazo styrene precursor. Thus, depending on the substitution pattern of the double bond and the electronic properties of the diazo precursors, the cyclopropanes 2 or 7, naphtalenes 8, or pyrazolines 17 were formed. The byproducts 8 and 17 originated from different, nonoverlapping mechanisms. Among the racemates synthesized, three compounds (1a, 22a, and 22b) showed increased selectivity for α2A vs. α2B and α2C receptor subtypes, and consequently were prepared in enantiomerically pure form. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
High‐Yielding Microwave‐Assisted Synthesis of Triazole‐Linked Glycodendrimers by Copper‐Catalyzed [3+2] Cycloaddition
Authors: Joosten John A. F. , Tholen Niels T. H. , Ait El Maate Fatna , Brouwer Arwin J. , van Esse G. Wilma , Rijkers Dirk T. S. , Liskamp Rob M. J. , Pieters Roland J.
Published: July 2005

A facile and high‐yielding synthesis of multivalent 1,4‐disubstituted 1,2,3‐triazole‐linked glycodendrimers is described. Azido carbohydrates are linked by a CuI‐catalyzed [3+2] cycloaddition reaction to dendritic acetylenes using microwave irradiation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Three‐Phase Microemulsion/Sol‐Gel System for Aqueous Catalytic Hydroformylation of Hydrophobic Alkenes
Authors: Abu‐Reziq Raed , Avnir David , Blum Jochanan
Published: July 2005

We extended the three‐phase transport methodology to the catalytic hydroformylation of alkenes. The method enables to carry out an all‐hydrophobic reaction – substrate, product and catalyst – in water. The alkene is microemulsified in the aqueous medium and the solubilized substrate is assumed to be carried to an organometallic rhodium catalyst entrapped within a partially hydrophobicized silica sol‐gel matrix. The substrate is then spilled into the porous heterogenized catalyst in which the hydroformylation takes place. The products formed are desorbed from the ceramic material and microemulsified by the same surfactant. Upon breaking of the microemulsion the products are separated. The heterogenized catalyst can be easily separated from the reaction mixture by filtration and be recycled. The hydroformylation process was carried out on various alkenes with reaction yields from ca. 62 to 99 %. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Characterization of 6q abnormalities in childhood acute myeloid leukemia and identification of a novel t(6;11)(q24.1;p15.5) resulting in a NUP98–C6orf80 fusion in a case of acute megakaryoblastic leukemia
Authors: Tosi Sabrina , Ballabio Erica , Teigler‐Schlegel Andrea , Boultwood Jackie , Bruch Jochen , Harbott Jochen
Published: July 2005

Chromosome abnormalities of 6q are not frequently observed in myeloid disorders. In this article, we report the incidence of these chromosome changes in childhood myeloid leukemia as 2%–4% based on the cytogenetic database of a single institution. We applied fluorescence in situ hybridization (FISH) to characterize precisely the types of 6q abnormalities in seven patients (six with acute myeloid leukemia and one with myelodysplastic syndrome). They carried various translocations involving different breakpoints in 6q, as confirmed by FISH using a whole‐chromosome‐6 paint. Four cases were reported as t(6;11), although the breakpoints varied. Among these, we identified a novel translocation, t(6;11)(q24.1;p15.5), in a patient with acute megakaryoblastic leukemia. Molecular cytogenetic studies using the PAC clone RP5‐1173K1 localized the genomic breakpoint on chromosome 11 to within the NUP98 gene. The breakpoint on chromosome 6 was narrowed down to a 500‐kb region between BAC clones RP11‐721P14 and RP11‐39H10. Reverse‐transcription PCR was performed using a forward primer specific for NUP98 and a reverse primer for the candidate gene in the 500‐kb interval in 6q. This experiment resulted in the identification of a new fusion between NUP98 and C6orf80. Further studies will aim to fully characterize C6orf80 and will elucidate the role of this new NUP98 fusion in myeloid leukemia. © 2005 Wiley‐Liss, Inc.
Emotional availability: Differential predictions to infant attachment and kindergarten adjustment based on observation time and context
Authors: Biringen Zeynep , Damon Jamie , Grigg Wendy , Mone Jen , Pipp‐Siegel Sandra , Skillern Shauna , Stratton Janie
Published: July 2005

Two studies are used to illustrate the importance of context and length of time in the use of the Emotional Availability Scales (EAS) to predict aspects of child development. The purpose of the first study was to examine whether prediction of attachment by the EAS is better with increasing amounts of time. We scored emotional availability (EA) every 15 min for a total of 2 hr, with correlations showing an increasingly stronger relation with attachment with increasing time. In addition, difference scores were calculated between the first and the last 15 min for each EAS dimension. The difference score was significantly higher for the insecure group, suggesting that we need more observation time for the prediction of insecure attachments than is the case for the prediction of secure attachments. The second study investigated whether EA is differentially predictive based on context. We explored play contexts versus reunion contexts. We also explored the relations with other indices of child development. Results revealed that some dimensions of EA (e.g., maternal nonhostility) are difficult to detect outside of a stress context. Maternal nonhostility during the reunion (but not the play situation) was correlated with child aggression in the kindergarten classroom. In addition, most dimensions of EA assessed in the reunion context were better predictors of teacher reports of kindergarten adjustment than was EA assessed in the play situation.
Negative emotional reactivity and regulation in 12‐month‐olds following emotional challenge: Contributions of maternal–infant emotional availability in a low‐income sample
Authors: Little Christina , Carter Alice S.
Published: July 2005

We predicted that the quality of mother–infant play as measured by the second edition of the Emotional Availability Scales (EAS; Biringen, Robinson, & Emde, 1993) would be significantly associated with infant emotion regulation over and above infant emotional reactivity in response to an emotionally challenging event. Forty‐five 12‐month‐old infants and their mothers participated in a play session and a protocol designed to elicit infant emotional reactivity and emotion regulation. Emotional reactivity (initial negative response to stress) was conceptualized as reflective of infant temperament while emotion regulation was expected to be associated with emotional availability (EA). Dyads were primarily African American (72%), unmarried (93%), and low income. When compared to most studies using the EAS, this sample was characterized by higher levels of nonoptimal EA in both children and mothers. The expectation that EA would be related to infant emotion regulation was supported. Greater maternal hostility was significantly associated with infant difficulty in regulating distress during an emotion challenge and marginally associated with difficulty in emotion regulation in the postchallenge conditions, over and above the impact of emotional reactivity. There also were trends for infants from less emotionally available dyads to be more likely to experience difficulties in emotion regulation during and after the emotional challenge condition than infants from more emotional available dyads, over and above reactivity.
Gender and patterns of emotional availability in mother–toddler and father–toddler dyads
Authors: Lovas Gretchen S.
Published: July 2005

Recent research has revealed gender differences in emotional communication and affect regulation during early mother–child interactions that are consistent with later gender differences in relational behavior. The current study extends those findings to father–child interactions. Parent–toddler dyads were videotaped during quiet indoor play when the toddlers were 19 and 24 months old. The observations were coded with Biringen, Robinson, and Emde's (1998) Emotional Availability scales (3rd ed.), which yields scores for parent sensitivity, structuring, nonintrusiveness, and nonhostility, and for child responsiveness to and involvement of the parent. Analyses of mean differences revealed a consistent pattern of larger parent than child gender differences. Dyadic analyses revealed more complex results. Mother–daughter dyads displayed the highest scores, followed by mother–son, then father–daughter, and finally father–son dyads for all variables but hostility, which by 24 months was higher in same‐sex than in opposite‐sex dyads. Scores for father–son dyads more often fell below the scale point indicating “good enough” parenting than scores for other dyads. The inclusion of fathers in the sample extends previous findings both by eliciting an increased range of variation within child gender and by providing a first look at the emotional availability of fathers relative to that of mothers.
Applying the Emotional Availability Scales to children with disabilities
Authors: Biringen Zeynep , Fidler Deborah J. , Barrett Karen C. , Kubicek Lorraine
Published: July 2005

In this article, we describe issues regarding emotional availability and its application to children with disabilities. We then apply this approach to the scoring of emotional availability for caregiver–child interactions of children with disabilities, with information based on children with genetic mental retardation syndromes, children with autism, and children with hearing impairments.
Emotional availability in infant psychiatry
Authors: Wiefel Andreas , Wollenweber Susanne , Oepen Gabrielle , Lenz Klaus , Lehmkuhl Ulrike , Biringen Zeynep
Published: July 2005

In a child psychiatric population, 68 mother–child pairs were observed, with children ranging in age from 6 weeks to 3 years 10 months. The children were diagnosed using the Zero to Three DC 0–3 guidelines (Zero‐to‐Three, 1998). Each dyad also was rated in terms of the intensity of recommended therapeutic measures upon intake at our clinic. Following videotaping of parent–child interactions, the dyads were rated for emotional availability using the Emotional Availability Scales (EAS; Biringen, Robinson, & Emde, 1998). The group with feeding disorders showed the lowest EAS ratings. The group with regulation disorders (sleeping and crying disorders) had the highest ratings followed by the group with externalizing disorders (motor disorganized and/or aggressive behavior) and attachment disorders. Further, the lower the EAS ratings, the higher the intensity of recommended treatments for the family. These findings indicate the importance of standardized observing of parent–child interactions in infant psychiatric disorders. Some clinical impressions regarding the work with the EAS also are described.
Vinylpyrrolidone‐co‐(meth)acrylic acid inserts for ocular drug delivery: Synthesis and evaluation
Authors: Barbu Eugen , Sarvaiya Indrajeetsinh , Green Keith L , Nevell Thomas G , Tsibouklis John
Published: July 2005

Copolymeric hydrogels constituting of vinylpyrrolidone and methacrylic or acrylic acid repeat units have been prepared and investigated for their ability to act as controlled release vehicles in ophthalmic drug delivery. The materials were synthesized by radical‐induced polymerization in the presence of N,N′‐methylenebisacrylamide crosslinker, and the influences of network composition and drug solubility upon the swelling properties, adhesion behavior, and drug release characteristics were studied. In vitro release experiments showed that some of these materials could be useful vehicles for the delivery of drugs such as pilocarpine or chloramphenicol, while in vivo studies, using the rabbit model, confirmed their high potential for the controlled ocular delivery of pilocarpine hydrochloride. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Electrical polarization of plasma‐spray–hydroxyapatite coatings for improvement of osteoconduction of implants
Authors: Kato Reiko , Nakamura Satoshi , Katayama Keiich , Yamashita Kimihiro
Published: July 2005

We have established the electrical polarization method of hydroxyapatite (HA) coatings (HAC) for clinical use, such as dental and orthopedic implants. The HAC examined in the current study was prepared in titanium substrates by plasma spraying of β‐tricalcium phosphate (TCP) powders followed by hydrothermal treatment. The prepared HAC consisted of a single phase of HA, because the starting TCP phase was completely transformed to the HA phase during the posthydrothermal treatment. Polarization was carried out at the elevated temperature of 400°C under a d.c. field of 1 kV · cm−1. The electrical measurements showed that the stored charges of the polarized HAC were greater than the reported value of the sintered ceramic HA. The enhanced bioactivity of the polarized HAC was demonstrated using 1.5 simulated body fluid (SBF). The crystal growth from the SBF solution was accelerated on the negatively charged surface in comparison with the untreated HAC. Similar to the polarized ceramic HA, the current results confirmed that the bioactivity of HAC would be effective for improving the initial fixation by polarization. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Structure and dynamics of hydrated NH: An ab initio QM/MM molecular dynamics simulation
Authors: Intharathep Pathumwadee , Tongraar Anan , Sagarik Kritsana
Published: July 2005

A combined ab initio quantum mechanical/molecular mechanical (QM/MM) molecular dynamics simulation has been performed to investigate solvation structure and dynamics of NH in water. The most interesting region, the sphere includes an ammonium ion and its first hydration shell, was treated at the Hartree–Fock level using DZV basis set, while the rest of the system was described by classical pair potentials. On the basis of detailed QM/MM simulation results, the solvation structure of NH is rather flexible, in which many water molecules are cooperatively involved in the solvation shell of the ion. Of particular interest, the QM/MM results show fast translation and rotation of NH in water. This phenomenon has resulted from multiple coordination, which drives the NH to translate and rotate quite freely within its surrounding water molecules. In addition, a “structure‐breaking” behavior of the NH is well reflected by the detailed analysis on the water exchange process and the mean residence times of water molecules surrounding the ion. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1329–1338, 2005
Nonuniform charge scaling (NUCS): A practical approximation of solvent electrostatic screening in proteins
Authors: Schwarzl Sonja M. , Huang Danzhi , Smith Jeremy C. , Fischer Stefan
Published: July 2005

In molecular mechanics calculations, electrostatic interactions between chemical groups are usually represented by a Coulomb potential between the partial atomic charges of the groups. In aqueous solution these interactions are modified by the polarizable solvent. Although the electrostatic effects of the polarized solvent on the protein are well described by the Poisson–Boltzmann equation, its numerical solution is computationally expensive for large molecules such as proteins. The procedure of nonuniform charge scaling (NUCS) is a pragmatic approach to implicit solvation that approximates the solvent screening effect by individually scaling the partial charges on the explicit atoms of the macromolecule so as to reproduce electrostatic interaction energies obtained from an initial Poisson–Boltzmann analysis. Once the screening factors have been determined for a protein the scaled charges can be easily used in any molecular mechanics program that implements a Coulomb term. The approach is particularly suitable for minimization‐based simulations, such as normal mode analysis, certain conformational reaction path or ligand binding techniques for which bulk solvent cannot be included explicitly, and for combined quantum mechanical/molecular mechanical calculations when the interface to more elaborate continuum solvent models is lacking. The method is illustrated using reaction path calculations of the Tyr35 ring flip in the bovine pancreatic trypsin inhibitor. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1359–1371, 2005
Cytoskeletal remodeling in vascular smooth muscle cells in response to angiotensin II‐induced activation of the SHP‐2 tyrosine phosphatase
Authors: Fernstrom Karl , Farmer Paul , Ali M. Showkat
Published: July 2005

Angiotensin II is an octapeptide that regulates diverse cellular responses including the actin cytoskeletal organization. In this study, stable cell lines overexpressing wild‐type or catalytically inactive SHP‐2 were employed to elucidate the signaling pathway utilized by the SHP‐2 tyrosine phosphatase that mediates an angiotensin II‐induced reorganization of the actin cytoskeleton in vascular smooth muscle cells (VSMC). The expression of wild‐type SHP‐2 prevented an angiotensin II dependent increase in stress fiber formation. In contrast, the catalytically inactive mutant SHP‐2 increased stress fiber formation. Additional observations further established that SHP‐2 regulates the reorganization of the actin cytoskeleton through RhoA‐ and Vav2‐dependent signaling pathways. The expression of wild‐type SHP‐2 caused a dephosphorylation of several focal adhesion associated proteins including paxillin, p130Cas, and tensin in VSMC. This dephosphorylation of focal adhesion associated proteins was accompanied by significantly decreased numbers of focal adhesions within cells. These results demonstrate a unique role for SHP‐2 in the regulation of the cellular architecture of VSMC, suggesting the possibility that this phosphatase might be instrumental in vascular remodeling. © 2005 Wiley‐Liss, Inc.
Nuclear sphingomyelin pathway in serum deprivation‐induced apoptosis of embryonic hippocampal cells
Authors: Albi Elisabetta , Cataldi Samuela , Bartoccini Elisa , Magni Mariapia Viola , Marini Francesca , Mazzoni Francesca , Rainaldi Giuseppe , Evangelista Monica , Garcia‐Gil Mercedes
Published: July 2005

Sphingomyelin (SM) cycle has been involved in the regulation of proliferation, differentiation, and apoptosis. Increases in ceramide have been found after a larger number of apoptotic stimuli including cytokines, cytotoxic drugs, and environmental stresses. Accumulating evidence suggest that the subcellular localization of ceramide generation is a critical factor in determining the cellular behavior. Since recently enzymes involved in ceramide metabolism such as sphingomyelinase, SM synthase, sphingosine kinase and ceramidase have been found in the nucleus of hepatocyte cells, we have studied first the presence and the physicochemical characteristics of SM metabolism enzymes in nuclei isolated from embryonic hippocampal cells (cell line HN9.10e). The activities of sphingomyelinase and SM‐synthase have been assayed and the ceramide production evaluated at different times after serum deprivation in these neurones cultivated in serum‐deficient medium. We report that both enzymes are present in the nucleus of embryonic hippocampal cells and differ from those present in the homogenate in optimum pH. After serum deprivation, that induces a time‐dependent decrease in cell viability and increase of the cell percentage in G1 phase of the cell cycle, a nuclear sphingomyelinase activation together with SM‐synthase inhibition and a consequent increase of nuclear ceramide pool have been demonstrated. No similar enzyme activity modifications in homogenate have been identified. The possible role of nuclear sphingomyelinase/sphingomyelin‐synthase balance in serum deprivation‐induced apoptosis in the embryonic hippocampal cell is discussed. © 2005 Wiley‐Liss, Inc.
Melatonin synthesized by Jurkat human leukemic T cell line is implicated in IL‐2 production
Authors: Lardone Patricia J. , Carrillo‐Vico Antonio , Naranjo María C. , De Felipe Beatriz , Vallejo Alejandro , Karasek Michal , Guerrero Juan M.
Published: July 2005

Human lymphocytes have recently been described as an important physiological source of melatonin (N‐acetyl‐5‐methoxytryptamine), which could be involved in the regulation of the human immune system. On the other hand, stimulation of IL‐2 production by exogenous melatonin has been shown in the Jurkat human lymphocytic cell line. Furthermore, both melatonin membrane and nuclear receptors are present in these cells. In this study, we show that the necessary machinery to synthesize melatonin is present and active in resting and stimulated Jurkat cells. Accordingly, we have found that cells synthesize and release melatonin in both conditions. Therefore, we investigated whether endogenous melatonin produced by Jurkat cells was involved in the regulation of IL‐2 production. When melatonin membrane and nuclear receptors were blocked using specific antagonists, luzindole and CGP 55644, respectively, we found that IL‐2 production decreased, and this drop was reverted by exogenous melatonin. Additionally, PHA activation of Jurkat cells changed the profile of melatonin nuclear receptor mRNA expression. A previous study showed that exogenous melatonin is able to counteract the decrease in IL‐2 production caused by prostaglandin E2 (PGE2) in human lymphocytes via its membrane receptor. In our model, when we blocked the melatonin membrane receptor with luzindole, the inhibitory effect of PGE2 on IL‐2 production was higher. Therefore, we have demonstrated the physiological role of endogenous melatonin in this cell line. These findings indicate that endogenous melatonin synthesized by human T cells would contribute to regulation of its own IL‐2 production, acting as an intracrine, autocrine, and/or paracrine substance. © 2005 Wiley‐Liss, Inc.
Clonal analysis of the differentiation potential of human adipose‐derived adult stem cells
Authors: Guilak Farshid , Lott Kristen E. , Awad Hani A. , Cao Qiongfang , Hicok Kevin C. , Fermor Beverley , Gimble Jeffrey M.
Published: July 2005

Pools of human adipose‐derived adult stem (hADAS) cells can exhibit multiple differentiated phenotypes under appropriate in vitro culture conditions. Because adipose tissue is abundant and easily accessible, hADAS cells offer a promising source of cells for tissue engineering and other cell‐based therapies. However, it is unclear whether individual hADAS cells can give rise to multiple differentiated phenotypes or whether each phenotype arises from a subset of committed progenitor cells that exists within a heterogeneous population. The goal of this study was to test the hypothesis that single hADAS are multipotent at a clonal level. hADAS cells were isolated from liposuction waste, and ring cloning was performed to select cells derived from a single progenitor cell. Forty‐five clones were expanded through four passages and then induced for adipogenesis, osteogenesis, chondrogenesis, and neurogenesis using lineage‐specific differentiation media. Quantitative differentiation criteria for each lineage were determined using histological and biochemical analyses. Eighty one percent of the hADAS cell clones differentiated into at least one of the lineages. In addition, 52% of the hADAS cell clones differentiated into two or more of the lineages. More clones expressed phenotypes of osteoblasts (48%), chondrocytes (43%), and neuron‐like cells (52%) than of adipocytes (12%), possibly due to the loss of adipogenic ability after repeated subcultures. The findings are consistent with the hypothesis that hADAS cells are a type of multipotent adult stem cell and not solely a mixed population of unipotent progenitor cells. However, it is important to exercise caution in interpreting these results until they are validated using functional in vivo assays. © 2005 Wiley‐Liss, Inc.
Usefulness of magnetic resonance imaging for evaluation of cardiovascular invasion: Evaluation of sliding motion between thoracic mass and adjacent structures on cine MR images
Authors: Seo Jae Seung , Kim Young Jin , Choi Byoung Wook , Choe Kyu Ok
Published: July 2005

Purpose

To determine the feasibility and usefulness of magnetic resonance imaging (MRI) for evaluating cardiovascular invasion of a thoracic mass by demonstrating the sliding motion between the mass and adjacent structures.

Materials and Methods

Twenty‐six patients (17 males and nine females, mean age = 49 years) were included in this study. They all had thoracic masses with equivocal cardiovascular invasion on chest CT scan and/or MRI that were surgically confirmed. The pathologic diagnoses were teratoma/thymic tumor (N = 12), lung cancer (N = 9), and other thoracic tumor (N = 5). Conventional T1/T2, contrast‐enhanced, and breathheld ECG‐gated cine MRI using a steady‐state free precession (SSFP) technique was performed. The results were compared to the surgical reports.

Results

The cine MR images showed the presence of sliding motion in 39 structures in 20 patients, which were surgically confirmed as not being invaded, and 15 structures in six patients with the absence of sliding motion noted as tumor invasion. Therefore, the accuracy of the cine MR images was 94.4% (51/54) for evaluating cardiovascular invasion of a thoracic mass.

Conclusion

MRI can provide additional information and improve the accuracy of preoperative staging for predicting cardiovascular invasion of a thoracic mass by evaluating the sliding motion. J. Magn. Reson. Imaging 2005;22:234–241. © 2005 Wiley‐Liss, Inc.
Intraindividual comparison of 1.0 M gadobutrol and 0.5 M gadopentetate dimeglumine for time‐resolved contrast‐enhanced three‐dimensional magnetic resonance angiography of the upper torso
Authors: Fink Christian , Puderbach Michael , Ley Sebastian , Risse Frank , Kuder Tristan A. , Bock M. , Thaler Julian , Plathow Christian , Kauczor Hans‐Ulrich
Published: July 2005

Purpose

To compare the signal characteristics and bolus dynamics of 1.0 M gadobutrol and 0.5 M Gd‐DTPA for time‐resolved, three‐dimensional, contrast‐enhanced (CE) MRA of the upper torso.

Materials and Methods

Ten healthy volunteers were examined with time‐resolved three‐dimensional CE‐MRA (scan time per three‐dimensional data set: 0.86 second; voxel size: 3.6 × 2 × 6.3 mm3). Each volunteer underwent eight individual examinations after intravenous injection of 0.05 and 0.1 mmol/kg body weight (b.w.) of 1.0 M gadobutrol and 0.5 M Gd‐DTPA using two injection rates (2.5 and 5 mL/second). The data analysis included quantitative measurements of the peak signal‐to‐noise ratio (SNR) and bolus dispersion (full width at half maximum (FWHM)) in the pulmonary artery, left atrium, and thoracic and abdominal aortas.

Results

No significant differences in the peak SNR and bolus dispersion were observed between gadobutrol and Gd‐DTPA for all dose levels and injection rates in any of the vascular segments. For both contrast agents a dose of 0.1 mmol/kg b.w. injected with 5 mL/second achieved the highest SNR in all vascular segments.

Conclusion

For the imaging parameters used in this study, higher‐concentrated gadolinium chelates offer no relevant advantages for time‐resolved three‐dimensional CE‐MRA of the upper torso. J. Magn. Reson. Imaging 2005;22:286–290. © 2005 Wiley‐Liss, Inc.
Preliminary study on the monitoring of glutathione S‐tranferase activity toward styrene oxide by electromigration methods
Authors: Šišková Zdeňka , Glatz Zdeněk , Kahle Vladislav
Published: July 2005

A new method has been developed for the monitoring of glutathione S‐tranferase (GST) detoxification activity toward styrene oxide (SO). The enzymatic reaction was carried out directly in a thermostatted autosampler vial and the formation of conjugates between glutathione (GSH) and SO was monitored by sequential MEKC runs. The determinations were performed in a 50‐μm fused silica capillary using 50 mM SDS in 20 mM phosphate 20 mM tetraborate buffer (pH 8.3) as a background electrolyte; separation voltage 28 kV (positive polarity), temperature of capillary 25°C, and detection at 200 nm. The method is rapid, amenable to automation, and requires only small amounts of samples, which is especially important in the case of GST isoenzyme analyses.
Kinetics and mechanism of oxidation of D‐fructose and D‐glucose by sodium salts of N‐(chloro)‐mono/di‐substituted benzenesulfonamides in aqueous alkaline medium
Authors: Gowda B. Thimme , Damodara N. , Jyothi K.
Published: July 2005

In an effort to introduce N‐chloroarylsulfonamides of different oxidizing strengths, nine sodium salts of mono‐ and di‐substituted N‐chloroarylsulfonamides are employed as oxidants for studying the kinetics of oxidation of D‐fructose and D‐glucose in aqueous alkaline medium. The results are analyzed along with those by the sodium salts of N‐chlorobenzenesulfonamide and N‐chloro‐4‐methylbenzenesulfonamide. The reactions show first‐order kinetics each in [oxidant], [Fru/Glu], and [OH−]. The rates slightly increase with increase in ionic strength of the medium. Further, the rate of oxidation of fructose is higher by 4 to 5 times than that of the glucose oxidation, by the same oxidant. Similarly, Ea values for glucose oxidations are higher by about 1.5 times the Ea values for fructose oxidations. The results have been explained by a plausible mechanism, and the related rate law deduced. The significant changes in the kinetics and thermodynamic data are observed with change of substituent in the benzene ring. It is because Cl+ is the effective oxidizing species in the reactions of N‐chloroarylsulfonamides. The oxidative strengths of the latter therefore depend on the ease with which Cl+ is released from them. The ease with which Cl+ is released from N‐chloroarylsulfonamides depends on the electron density of the nitrogen atom of the sulfonamide group, which in turn depends on the nature of the substituent in the benzene ring. The following Hammett equations are valid for the oxidation of fructose and glucose, log kobs = −3.13 + 0.54 σp and log kobs = −3.81 + 0.28 σp, respectively. The enthalpies and entropies of activations for oxidations by all the N‐chloroarylsulfonamides correlate well with isokinetic temperatures of 301 K and 299 K, for fructose and glucose oxidations, respectively. The effect of substitution in the oxidants on the Ea and log A for the oxidations is also considered. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 572–582, 2005
Kinetics of oxidation of adenosine by t‐butoxyl radical: Protection and repair by caffeic acid
Authors: Charitha L. , Adinarayana M.
Published: July 2005

The kinetics of oxidation of adenosine and caffeic acid by t‐BuO• has been studied by the photolysis of t‐BuOOH in the presence of t‐BuOH. The rates and the quantum yields (φ) of oxidation of caffeic acid by t‐BuO• radicals have been determined in the absence and presence of varying concentrations of adenosine. An increase in the concentration of adenosine has been found to decrease the rate of oxidation of caffeic acid suggesting that adenosine and caffeic acid compete for t‐BuO• radicals. From competition kinetics, the rate constant of t‐BuO•–caffeic acid reaction has been calculated to be 8.15 × 108 dm3 mol−1 s−1. The results of experimentally determined quantum yield (φexptl) values of oxidation of caffeic acid and the quantum yield values calculated (φcal) by assuming that caffeic acid reacts only with t‐BuO• radicals suggest that caffeic acid not only protects adenosine from t‐BuO• radicals but also repairs adenosine radicals formed by the reaction of t‐BuO• radicals. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 515–521, 2005
Indigo dyes as indicators for oxidation reactions: Competition kinetic studies
Authors: Al‐Ajlouni Ahmad M.
Published: July 2005

The use of indigo dyes as competiters to study the kinetics of oxidation reactions is reported. The kinetic model was theoretically investigated using the kinetic simulation program KinSim under conditions involving very limiting concentrations of the indigo dye relative to both the oxidant and the reductant. Complete kinetic results on the reaction of an oxidant with a reductant can be obtained indirectly from observing the absorbance changes due to the loss in the indigo dye at 600 nm (ε600∼2 × 104 M−1cm−1). Experimental data from the oxidation of an olefin (cyclohexene) with m‐chloroperoxybenzoic acid in the presence of an indigo dye were used to check the validity of the kinetic model. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 532–537, 2005
Carbothermal synthesis of titanium nitride (TiN): Kinetics and mechanism
Authors: Ortega A. , Roldan M. A. , Real C.
Published: July 2005

Constant rate thermal analysis (CRTA) has been used for studying the kinetics of the carbothermal reduction of anatase in nitrogen. It is noteworthy to point out the ability of CRTA method for discriminating the kinetic law of solid‐state reactions with considerably higher precision than conventional (TG, DTA, isothermal etc.) methods. The precise control of the reaction rate implies either direct or indirect control of both the partial pressure of CO generated in the reaction and the heat evolution rate, which allows to minimize the influence of heat and mass transfer phenomena.

It has been shown that this synthesis is best described by a Johnson–Mehl–Avrami (with n = 2) kinetic model with an activation energy that fall in the range 162–165 kJ mol−1. Finally the results reported here constitute the first attempt to use the new CRTA method to study the kinetics of the carbothermal synthesis of TiN. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 566–571, 2005
Intramolecular reactions of free radicals formed from artemisinin
Authors: Denisov Evgeny , Denisova Taisa , Ismail Fyaz
Published: July 2005

Two cyclic alkoxyl radicals are formed as a result of peroxide bridge scission in artemisinin. Intramolecular reactions of these radicals induce the cascade of reactions of isomerization, decyclization, and decomposition of formed free radicals. It includes 14 reactions of intramolecular free radical hydrogen transfer, 17 reactions of decyclization of alkoxyl and alkyl radicals, and 4 reactions of decomposition of alkoxyl, acyl, and carboxyl radicals. The enthalpies of these 35 reactions are calculated. Using intersection parabolas method, activation energies and rate constants of all these reactions are calculated. The most rapid reactions are selected for every intermediate free radical. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 554–565, 2005
Dielectric Study of the Effect of a Sol‐Gel Inorganic Network on Polymeric Relaxation Dynamics in Acrylic/Titania Hybrids
Authors: Perrin François X. , Nguyen Van Nhan , Vernet Jean L.
Published: July 2005

Summary: In this research, poly[(methyl methacrylate)‐co‐(butyl methacrylate)‐co‐(methacrylic acid)]/TiO2 hybrids were prepared by the sol‐gel process. The copolymer composition was 16 mol‐% methyl methacrylate (MMA), 80 mol‐% butyl methacrylate (BMA) and 4 mol‐% methacrylic acid (MA). The dielectric properties of the hybrids with varying titania content were measured over the frequency range 0.1 Hz to 100 kHz and between 25 and 160 °C. In addition, the hybrids were investigated using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). In the given frequency range, a single relaxation peak was observed both by dielectric relaxation spectroscopy (DRS) and DMTA. The single relaxation observed by DRS behaves in the manner of an α‐relaxation, with the frequency–temperature locus showing non‐Arrhenius behavior (curved downwards like a VTF law). The change in the DRS and DMTA characteristics in hybrids compared to the pure polymer reflect the presence of antagonistic mechanisms controlling the dynamics of the polymer chains: nanodomains with enhanced and restricted mobilities are suggested to be responsible for the broadening of the isochronal dielectric loss curve toward, respectively, the low and the high temperature sides. Combining the DSC and DRS results, it can be inferred that the domains with enhanced mobility result from internal and external plasticization effects that reduce the intermolecular hydrogen bonds between the polymer chains. Besides, the motion of polymer chains is found to be significantly hindered by the titania network, due to the presence of iono‐covalent bonds between the polymer and titania and geometrical restrictions in high junction‐point density and titania‐rich microphases. From the Arrhenius plot, it is also shown that the addition of sol‐gel titania more severely hinders the segmental motion of the macromolecular chains than the local motion of the lateral groups (β relaxation).

Simplified schematic morphology for the poly(MMA‐co‐BMA‐co‐MA)/TiO2 hybrids.

magnified image

Simplified schematic morphology for the poly(MMA‐co‐BMA‐co‐MA)/TiO2 hybrids.
DNA methylation in the CTCF‐binding site I and the expression pattern of the H19 gene: Does positive expression predict poor prognosis in early stage head and neck carcinomas?
Authors: Esteves Leda I.C.V. , Javaroni Afonso C. , Nishimoto Inês N. , Magrin José , Squire Jeremy A. , Kowalski Luiz P. , Rainho Cláudia A. , Rogatto Silvia R.
Published: July 2005

Loss of allele‐specific expression by the imprinted genes IGF2 and H19 has been correlated with a differentially methylated region (DMR) upstream to the H19 gene. The H19‐DMR contains seven potential CCCTC‐binding factor (CTCF) binding sites. CTCF is a chromatin insulator and a multifunctional transcription factor whose binding to the H19‐DMR is suppressed by DNA methylation. Our study included a group of 41 head and neck squamous cell carcinoma (HNSCC) samples. The imprinting status of the H19 gene was analyzed in 11 out of 35 positive cases for H19 gene expression, and only 1 of them showed loss of imprinting. We detected a significant correlation (P = 0.041, Fisher's exact test) between H19 expression and tumor recurrence. Among H19 positive cases, six were T2, in which five developed recurrence and/or metastasis. Inversely, in the group of tumors that showed no H19 gene expression, 5 out of 24 were T2 and only 1 presented regional recurrence. These data support the hypothesis that H19 expression could be used as a prognostic marker to indicate recurrence in early stage tumors. We also examined the methylation of the CTCF binding site 1 in a subgroup of these samples. The H19 gene silencing and loss of imprinting were not correlated with the methylation pattern of the CTCF binding site 1. However, the significant correlation between H19 expression and tumor recurrence suggest that this transcript could be a marker for the progression of HNSCC. © 2005 Wiley‐Liss, Inc.