bluuebunny/crossref_metadata_2025 huggingface dataset:
A Hitchhiker's Guide to Antisense and Nonantisense Biochemical Pathways
Authors: Branch A D
Published: November 2004

Antisense pharmaceutical research has sought to provide drugs that would yield effective therapies for diseases resulting from the production of deleterious proteins. The original concept was straightforward: eliminate production of unwanted proteins, such as oncogenic proteins, by blocking the function of their mRNAs; and block their mRNAs by adding “antisense” nucleic acids that bind them through complementary base pairing. However, it has proven difficult to develop clinically useful antisense strategies. Conventional antisense nucleic acids are large, highly charged, complex molecules that interact with a wide variety of unintended cellular and microbial components, often causing “nonantisense effects.” It is now clear that a broad knowledge of nucleic acid biochemistry will be needed to optimize antisense molecules for use in patients. The efficacy of naturally occurring antisense molecules and the success of antisense agricultural strategies prove that antisense approaches can be powerful and specific. Pharmaceutical antisense research can be expected to yield many valuable products once sufficient information about antisense mechanisms has been gathered and applied. This article explains the biochemical events that give rise to both antisense and nonantisense effects and provides guidelines for designing and evaluating antisense experiments.
Hippocampus and remote spatial memory in rats
Authors: Clark Robert E. , Broadbent Nicola J. , Squire Larry R.
Published: November 2004

Damage to the hippocampus typically produces temporally graded retrograde amnesia, whereby memories acquired recently are impaired more than memories acquired remotely. This phenomenon has been demonstrated repeatedly in a variety of species and tasks. It has also figured prominently in theoretical treatments of memory and hippocampal function. Yet temporally graded retrograde amnesia has not been demonstrated following hippocampal damage in spatial tasks like the water maze. We have assessed recent and remote spatial memory following hippocampal lesions in three different tests of spatial memory: (1) the standard water maze; (2) the Oasis maze, a dry‐land version of the water maze; and (3) the annular water maze, where training and testing occur within a circular corridor. Training protocols were developed for each task such that retention of spatial memory could be expressed after very long retention intervals. In addition, retention in each task was assessed with single probe trials so that the assessment of remote memory did not depend on the ability to relearn across multiple trials. The findings were consistent across the three tasks. In the standard water maze (Experiment 1), spatial memory was impaired after training–surgery intervals of 1 day, 8 weeks, or 14 weeks. Similarly, in the Oasis maze (Experiment 2), spatial memory was impaired after training–surgery intervals of 1 day and 9 weeks. Finally, in the annular water maze (Experiment 3), spatial memory was impaired after training–surgery intervals of 9 weeks and 14 weeks. Dorsal hippocampal lesions impaired performance to the same extent as complete lesions. The impairment in remote spatial memory could reflect disruption of previously acquired spatial information. Alternatively, it is possible that in these tasks hippocampal lesions might produce an impairment in performance that prevents the expression of an otherwise intact spatial memory. Published 2004 Wiley‐Liss, Inc.
Expression and prognostic value of lactoferrin mRNA isoforms in human breast cancer
Authors: Benaïssa Monique , Peyrat Jean‐Philippe , Hornez Louis , Mariller Christophe , Mazurier Joël , Pierce Annick
Published: November 2004

We investigated the expression levels of human lactoferrin (Lf), a steroid hormone‐inducible gene product the expression of which is often altered during oncogenesis, and of Δ‐lactoferrin (ΔLf), its alternative isoform, which has been shown to be absent from tumor cell lines in commonly used human breast epithelial cell lines, using semiquantitative RT‐PCR. Both mRNAs were detected but with levels of expression lower than those found in normal breast epithelial cells. This downregulation was much more visible forΔLfsince its expression was either significantly diminished (BT‐20, MCF‐7 cell lines) or practically absent (MDA‐MB‐231, T‐47D, HBL 100 cell lines). In order to determine whetherLfgene products are useful prognosic tools, we further analyzed their expression levels in 99 primary breast cancer biopsies. ΔLf transcripts were found in all of the samples, whereas Lf transcripts were found in 88% of them. Lf and ΔLf expression levels were positively correlated (p= 0.003). Lf expression was related to tumor type with a higher recovery in lobular‐type tumors (p= 0.04). ΔLf expression was related to the histoprognostic grading (p= 0.02). In univariate analyses, ΔLf and Lf expressions were prognosis parameters, high concentrations being associated with a longer overall survival. © 2004 Wiley‐Liss, Inc.
Poly(N‐isopropylacrylamide) copolymer films as vehicles for the sustained delivery of proteins to vascular endothelial cells
Authors: Kavanagh C. A. , Gorelova T. A. , Selezneva I. I. , Rochev Y. A. , Dawson K. A. , Gallagher W. M. , Gorelov A. V. , Keenan A. K.
Published: November 2004

The aim of this study was to establish the capacity of thermoresponsive poly(N‐isopropylacrylamide) copolymer films to deliver bioactive concentrations of vascular endothelial growth factor (VEGF165) to human aortic endothelial cells (HAEC) over an extended time period. Films were prepared using a 50:50 (w/w) mixture of non‐crosslinkable and crosslinkable copolymers of the following monomer compositions (w/w): 85:15, N‐isopropylacrylamide (NiPAAm):N‐tert‐butylacrylamide (NtBAAm); and 85:13:2 NiPAAm:NtBAAm:acrylamidobenzophenone (ABzPh, crosslinking agent), respectively. After crosslinking by UV irradiation, the ability of films to incorporate a fluorescently labeled carrier protein (FITC‐labeled BSA, 1 mg loaded per film), at 4°C, was first established. Incorporation into the matrix was confirmed by the observation that increasing film thickness from 5 to 10 μm increased release from collapsed films at 37°C (1.76 ± 0.15 and 10.98 ± 3.38 μg/mL, respectively, at 24 h postloading) and that this difference was maintained at 5 days postloading (1.81 ± 0.25 and 13.8 ± 2.3 μg/mL, respectively). Incorporation was also confirmed by visualization using confocal microscopy. When 10‐μm films were loaded with a BSA solution (1 mg/mL) containing VEGF165 (3 μg/mL), sustained release of VEGF165 was observed (10.75 ± 3.11 ng at 24 h; a total of 31.32 ± 8.50 ng over 7 days). Furthermore, eluted VEGF165 increased HAEC proliferation by 18.2% over control. The absence of cytotoxic species in medium released from the copolymer films was confirmed by the lack of effect of medium (incubated with copolymer films for 3 days) on HAEC viability. In conclusion this study has shown that NiPAAm:NtBAAm copolymers can be loaded with a therapeutic protein and can deliver bioactive concentrations to human vascular endothelial cells over an extended time period. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 25–35, 2005
Elution from light‐cured dental composites: Comparison of trimethacrylate and dimethacrylate as base monomers
Authors: Kim Joong‐Gon , Chung Chan‐Moon
Published: November 2004

The effect of the number of functional units on a monomer on the elution property of dental composites was first studied. Elution from a composite of a trifunctional methacrylate, 1,1,1‐tris[4‐(2′‐hydroxy‐3′‐methacryloyloxypropoxy)phenyl]ethane (THMPE), was compared to that of bis‐GMA, a typical difunctional base monomer in current dental composites. The degrees of cure and the water solubilities of composites prepared from the two kinds of methacrylates were measured. The concentration of unreacted methacrylates (base monomer and diluent) present in the photo‐cured composites as well as the quantity of the methacrylates eluted into water (or 75%, volume fraction, of ethanol in water) from the composites were determined by high‐performance liquid chromatography (HPLC). THMPE‐based composites showed lesser amounts of residual and eluted methacrylates when compared with bis‐GMA composites. This is attributed to the higher degree of functionality and larger molecular size of THMPE compared with those of bis‐GMA. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 328–333, 2005
Static mechanical properties of hydroxyapatite (HA) powder‐filled acrylic bone cements: Effect of type of HA powder
Authors: Morejón Lizette , Mendizábal Alonso Eduardo , García‐Menocal José Angel Delgado , Ginebra María Pau , Aparicio Conrado , Mur Francisco Javier Gil , Marsal Montserrat , Davidenko Natalia , Ballesteros María E. , Planell Josep Anton
Published: November 2004

This work reports on the effect of the amount (0, 10, and 30 wt %) and type of HA powder incorporated into an acrylic bone cement on the tensile properties, compression properties, and fracture toughness. The three different types of HA powders used were synthesized in the laboratory and coated with a silane agent prior to incorporation into the cement powder, and differed in particle size, water content, surface area, and crystallinity. It was found that the inclusion of any type of HA powder led to an increase in the tensile modulus (ET), but all the other mechanical properties of the cement decreased (relative to the values of the unfilled cement). The increase in ET is attributed to the good adhesion between the filler and the cement matrix, which is due to the silane coating agent. The decrease in the other mechanical properties may be a consequence of HA powder agglomeration and porosity. Hydroxyapatite morphology and crack‐growth mechanisms were analyzed by scanning electronic microscopy (SEM). © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 345–352, 2005
Enzymatic synthesis of [1‐14C‐N‐acetyl, P18O2] cytidine monophosphate neuraminic acid
Authors: Burke Erin E. , Horenstein Nicole A.
Published: November 2004

A method for the enzymatic synthesis of [1‐14C‐N‐acetyl, P18O2] cytidine monophosphate neuraminic acid (CMP‐NeuAc) is described. Central to the synthesis of [1‐14C‐N‐acetyl, P18O2]CMP‐NeuAc was the enzymatic preparation of [γ‐P18O3]ATP for use in a reaction with uridine kinase and cytidine to provide 5′‐[P18O3]CMP. The [1‐14C‐N‐acetyl, P18O2]CMP‐NeuAc isotopomer was then synthesized from a reaction involving nucleoside monophosphate kinase, pyruvate kinase and CMP‐NeuAc synthetase. The isolated reaction yield was 35%. Copyright © 2004 John Wiley & Sons, Ltd.
12th Workshop of the Central European Division e.V. of the International Isotope Society
Authors: Snieckus V. , Geach N. J. , Randall G. P. , Winfield C. J. , Studer A. , Spivey A. C. , Jones T. , Noban C. , Ellames G. J. , Kohler A. , Wadsworth H. , Rieke‐Zapp J. , Stone‐Elander S. , Goehl J. , Perry B. , Windels J. , Marx M. H. , Krüger J. , Manmontri B. , Fels G. , Wüst F. , Kniess T. , Bergmann R. , Mäding P. , Füchtner F. , Hilger C. S. , Halks–Miller M. , Horuk R. , Matei L. , Postolache C. , Fugaru V. , Condac E. , Dinischiotu A. , Costache M. , Matei L. , Postolache C. , Fugaru V. , Atzrodt J. , Derdau V.
Published: November 2004

V Snieckus [Queen's University, Canada]—The Directed Ortho Metalation—Cross Coupling Symbiosis in Aromatic Synthesis.

N Geach, GP Randall, CJ Winfield [Scynexis, UK]—Isotopically Labelled 4‐Formylimidazole.

A Studer [Marburg University, Germany]—New Concepts in Tin‐Free Radical Chemistry.

AC Spivey, C Noban [Imperial College London, UK]. T Jones [Sheffield University, UK], GJ Ellames, A Kohler [Sanofi‐Synthélabo, UK], H Wadsworth [Amersham Biosciences, UK]—Opportunities for Isotope Labelling via Solid Phase Synthesis with Organogermanium Linkers.

J Rieke‐Zapp [Aventis Pharma, Germany]—Optimization of Reaction Conditions on mg‐Scale by Use of Screening Devices.

S Stone‐Elander [Karolinska Institute, Sweden]—Rerouting Radiochemistry with Microwaves.

J Goehl, B Perry, D Leuck, J Windels, M Marx [EaglePicher Pharmaceutical, USA]—GMP and Radiolabelled Syntheses of Capsaicin.

J Krüger, B Manmontri, G Fels [Paderborn University, Germany]—H/D‐Exchange in Aromatic Systems Using Transition Metal Catalysis.

F Wüst, T Kniess, R Bergmann [Research Centre Rossendorf, Germany]—Synthesis of a 11C‐Labelled Nonsteroidal Glucocorticoid Receptor Ligand as Potential Radiotracer for Imaging Brain Glucocorticoid Receptors with Positron Emission Tomography (PET).

P Mäding, F Füchtner [Research Centre Rossendorf, Germany], CS Hilger [Schering AG, Germany]. M Halks‐Miller, R Horuk [Berlix Biosciences, USA]—18F‐Labelling of a Potent Nonpeptide CCR1 Antagonist for the Diagnosis of the Alzheimer's Disease.

L Matei, C Postolache, V Fugaru, E Condac, A Dinischiotu, M Costache [Bukarest University, Romania]—Use of [1,2‐3H] Testosterone in 5α‐ Reductase Enzymatic Activity Dosing in Dermal Fibroblast Cultures from Polycystic Ovarian Patients.

L Matei, C Postolache, V Fugaru [Bukarest University, Romania]—Synthesis and Stability Studies of Acyclovir Labelled with Tritium.

J Atzrodt, V Derdau [Aventis Pharma, Germany]—Studies on Directed Ortho‐Metalation (DoM) as Convenient Tool for the Synthesis of Labeled Compounds.
Stability of human cytomegalovirus genotypes in persistently infected renal transplant recipients
Authors: Stanton Richard , Westmoreland Diana , Fox Julie D. , Davison Andrew J. , Wilkinson Gavin W.G.
Published: November 2004

Although most genes are highly conserved among strains of human cytomegalovirus (HCMV), several are unusually variable. By analyzing the sequence of two variable genes (UL146 and UL74) amplified directly from whole blood DNA extracts, multiple HCMV strains were detected in blood samples from 5/11 virus‐infected renal transplant patients. These five patients were seronegative prior to transplantation and their likely acquisition of the virus was via the donated organ; HCMV‐positive immunocompetent donors may thus be capable of harboring and transmitting multiple virus genotypes. In sequential samples taken up to 140 days post transplant no mutations in either gene were detected from 9/10 patients, and in the remaining patient a single nucleotide change was detected in UL146, and none in UL74. All sequences grouped into previously defined genotypes, with the detection of multiple members of the UL74 group 5 genotype establishing this previously tentative genotype. Additionally, identical sequences were identified in viruses from different patients, including examples from geographically distinct regions. Thus, although UL146 and UL74 exhibit impressive variation among strains, their sequences are maintained stably within and between infected individuals, suggesting that sequence differences between genotypes may be driven by differing gene function. J. Med. Virol. 75:42–46, 2005. © 2005 Wiley‐Liss, Inc.
Impact of human metapneumovirus in childhood: Comparison with respiratory syncytial virus and influenza viruses
Authors: Bosis Samantha , Esposito Susanna , Niesters Hubert G.M. , Crovari Piero , Osterhaus Albert D.M.E. , Principi Nicola
Published: November 2004

This study evaluated the overall impact of human metapneumovirus (hMPV) infection in 1,505 children and their households, and compared it with infections due to respiratory syncytial virus (RSV) and influenza viruses. Nasopharyngeal swabs were used at enrollment to collect specimens for the detection of hMPV, RSV, and influenza virus RNA by reverse‐transcriptase polymerase chain reaction (RT‐PCR). hMPV was detected in 42 children (2.8%), RSV in 143 (9.5%; P < 0.0001 vs. hMPV), and influenza viruses in 230 (15.3%; P < 0.0001 vs. hMPV). Of the 42 hMPV‐positive samples, one was also positive for RSV and six for influenza viruses, for a co‐infection rate of 16.7%. Clinically, hMPV was identified only in patients with acute respiratory infection, whereas RSV and influenza viruses were also detected in patients with different clinical manifestations. Symptoms with statistically significant different proportions at presentation were fever (more frequent in the hMPV‐ and influenza‐positive children) and wheezing with bronchiolitis or asthma exacerbation (more frequent among hMPV‐ and RSV‐positive cases). The households of the hMPV‐ and the influenza‐positive children had significantly more illnesses, needed significantly more medical visits, received more antipyretics, and missed significantly more work or school days than those of the RSV‐positive children. Results show that hMPV is an emerging cause of acute respiratory infection in childhood, and may have a significant clinical and socioeconomic impact on children and their families. J. Med. Virol. 75:101–104, 2005. © 2005 Wiley‐Liss, Inc.
Sox10 acts as a tissue‐specific transcription factor enhancing activation of the myelin basic protein gene promoter by p27Kip1 and Sp1
Authors: Wei Qiou , Miskimins W. Keith , Miskimins Robin
Published: November 2004

Myelin basic protein (MBP) is one of the major components of the myelin sheath that insulates axons. In the central nervous system, MBP is synthesized by differentiating oligodendrocytes. The expression of MBP in oligodendrocytes is regulated mainly at the transcriptional level. The Sp1 family of transcription factors has been shown to be important in the regulation of many genes. Binding of Sp1 to the GC box in the proximal MBP promoter has been shown to be indispensable for the activation of MBP gene expression. Previous results from our laboratory have shown that the increase in p27Kip1 that accompanies oligodendrocyte differentiation is paralleled by an increase in Sp1. We also have shown that the increase in MBP expression resulting from elevated p27Kip1 levels is mediated through Sp1 and that this effect occurs specifically in oligodendrocytes. In this study, we found that increased expression of p27Kip1 together with the nervous‐system‐specific transcription factor Sox10 can activate the MBP promoter even in nonoligodendrocyte cells. This indicates that Sox10 confers cell type specificity on the expression of MBP. Both Sp1 and Sox10 can enhance MBP promoter activity when expressed alone. Cotransfection of plasmids encoding Sp1 and Sox10 induces increased activation of the MBP promoter over expression of either transcription factor alone. This effect is not limited to oligodendrocyte cell lines, in that Sp1 and Sox10 can also synergistically activate the MBP promoter when expressed in NIH3T3 fibroblasts. Mutation of the Sp1 binding sites in the MBP promoter eliminates Sox10 stimulated activation, suggesting that the MBP promoter is activated, at least in part, through protein–protein interactions between Sp1 and Sox10. © 2004 Wiley‐Liss, Inc.
3α,5α‐tetrahydroprogesterone (allopregnanolone) and γ‐aminobutyric acid: Autocrine/paracrine interactions in the control of neonatal PSA‐NCAM+ progenitor proliferation
Authors: Gago Nathalie , El‐Etr Martine , Sananès Nicole , Cadepond Françoise , Samuel Denise , Avellana‐Adalid Virginia , Baron‐Van Evercooren Anne , Schumacher Michael
Published: November 2004

The earliest identified neonatal neural progenitors are cells that express the polysialylated form of the neural cell adhesion molecule (PSA‐NCAM). One of these progenitors is the early PSA‐NCAM+ progenitor (ePSA‐NCAM+ progenitor; Gago et al. [2003] Mol Cell Neurosci 22:162–178), which corresponds to a multipotential cell with a default differentiation through glial lineages. The ePSA‐NCAM+ progenitor can synthesize the neurosteroid progesterone (PROG) and its reduced metabolite 3α,5α‐tetrahydroprogesterone (3α,5α‐THP, or allopregnanolone; Gago et al. [ 2001] Glia 36:295–308). The latter is a potent positive allosteric modulator of γ‐aminobutyric acid type A (GABAA) receptors. In the present work, we demonstrate that PROG and 3α,5α‐THP both stimulate ePSA‐NCAM+ progenitor proliferation. PROG exerted its mitogenic effect indirectly, through its conversion to 3α,5α‐THP, since it could be abolished by an inhibitor of the 5α‐reductase (L685‐273) and mimicked by 3α,5α‐THP. A dose‐response curve revealed a bell‐shaped effect of 3α,5α‐THP on ePSA‐NCAM+ progenitor proliferation, with greatest stimulation at nanomolar concentrations. The mitogenic effect of 3α,5α‐THP was mediated by GABAA receptors, insofar as it could be blocked by the selective antagonist bicuculline. ePSA‐NCAM+ progenitors indeed expressed mRNAs for GABAA receptor subunits, and GABA enhanced cell proliferation, an effect that was also bicuculline sensitive. Moreover, these cells synthesized GABA, which was involved in a tonic stimulation of their proliferation. These results reveal complex autocrine/paracrine loops in the control of ePSA‐NCAM+ progenitor proliferation, involving both neurosteroid and GABA signaling, and suggest a novel key role for 3α,5α‐THP in the development of the nervous system. © 2004 Wiley‐Liss, Inc.
Bioactive phenolic compounds of cowpeas (Vigna sinensis L). Modifications by fermentation with natural microflora and with Lactobacillus plantarum ATCC 14917
Authors: Dueñas Montserrat , Fernández Dolores , Hernández Teresa , Estrella Isabel , Muñoz Rosario
Published: November 2004

In this work we have determined the phenolic composition of raw cowpeas (Vigna sinensis L) of the variety Carilla by HPLC/PAD/MS and have studied the effect of fermentation, both spontaneous and with Lactobacillus plantarum ATCC 14917, on the phenolic compounds. This variety contains mainly ferulic and p‐coumaric acids esterified with aldaric acids, together with the cis and trans isomers of the corresponding free acids. Hydroxybenzoic acids such as gallic, vanillic, p‐hydroxybenzoic and protocatechuic were also found, along with flavonols such as a myricetin glucoside, mono‐ and diglycosides of quercetin and a quercetin diglycoside acylated with ferulic acid. Fermentation, both spontaneous and inoculated, modifies the content of phenolic compounds, but differently in each case. The antioxidant activity as free radical‐scavenging activity has also been evaluated. Fermentation followed by heating has been shown to be a very effective process to increase the functionality of this variety of V sinensis. For this reason, this cowpea variety could be used as an ingredient to obtain high value‐added flours. Copyright © 2004 Society of Chemical Industry
Electrochemical behavior of titanium‐tantalum alloys in sulfuric acid solutions
Authors: de Souza K. A. , Robin A.
Published: November 2004

Titanium exhibits a good corrosion resistance in oxidizing acids and neutral media but it is severely attacked in reducing acids. On the contrary, tantalum presents an excellent resistance in both oxidizing and reducing acids, but its high cost limits its use to very aggressive conditions. The titanium‐tantalum alloys are promising materials for use in reducing acids, due to their lower cost and density when compared to tantalum, and their higher corrosion resistance when compared to titanium. Titanium‐20, 40, 60 and 80 wt% tantalum alloys were prepared by arc‐melting and their microstructures were characterized by scanning electron microscopy and X‐ray diffractometry. Their electrochemical behaviors were studied in 20 to 80 wt% sulfuric acid solutions at room temperature, using open‐circuit potential measurements, potentiodynamic polarization and electrochemical impedance spectroscopy. Different behaviors were observed depending on the tantalum content and acid concentration. A clear tendency of increase in corrosion resistance with the increase of tantalum content is observed, especially in 80 wt% sulfuric acid solutions.
Selective Electroless Deposition of Cu on an Ultrathin Au Film Pattern
Authors: Zhang Maofeng , Lu Conghua , Cong Hailin , Cao Weixiao
Published: November 2004

Summary: In this report an ultrathin Au nanoparticle (AuNP) film composed of photosensitive diazoresin (DR) and mercaptophenol (MP) capped AuNPs (MP‐AuNPs) was fabricated by self‐assembly (SA). The DR/MP‐AuNP film was then patterned through a photomask by selective exposure to UV light and instantly developed in sodium dodecyl sulfate (SDS) aqueous solution. After sintering at 550 °C to remove the organic components, the DR/MP‐AuNPs formed AuNPs. Taking advantage of the catalytic susceptibility of AuNPs toward electroless deposition of Cu, a Cu film micropattern with fine resolution (ca. 2–3 μm) and considerable thickness (ca. 130 nm) was prepared.

SEM image of the micropatterned Cu film on a silicon substrate; scale bar: 10 μm.

magnified image

SEM image of the micropatterned Cu film on a silicon substrate; scale bar: 10 μm.
Synthesis of Highly Branched Comblike Polymers Having One Branch in Each Repeating Unit by Linking Reaction of Polystyryllithium with Well‐Defined New Epoxy‐Functionalized Polystyrene
Authors: Hirao Akira , Shimohara Norihide , Ryu Sang Woo , Sugiyama Kenji
Published: November 2004

Highly branched comblike polymers having one branch in each repeating unit were successfully synthesized by the linking reaction of polystyryllithium (PSLi) with new epoxy‐functionalized polystyrenes, poly(4‐(3,4‐epoxybutyl)styrenes, (1). The reaction of PSLi with 1 proceeded very fast to reach 88 % efficiency after 1 h and was complete within 24 h under the conditions in THF at −78 °C. A high molecular weight PSLi (Mw = 56.2 kg/mol) could be completely reacted with 1 (Mw = 8.36 kg/mol) to introduce into each of all epoxy reaction sites. However, the linking efficiency decreased with increasing the molecular weights of PSLi and especially 1. With use of a high molecular weight 1 (Mw = 71.8 kg/mol), even a low molecular weight PSLi (Mw = 4.28 kg/mol) could not be quantitatively introduced into all epoxy functions, although a high efficiency of 88 % was achieved. The influence of both molecular weights on linking efficiency was examined in detail.
Semicontinuous Emulsion Copolymerization of Vinyl Acetate and Butyl Acrylate Using Different Initiators and Different Chain Length Emulsifiers
Authors: Saraç Ayfer
Published: November 2004

The semicontinuous emulsion copolymerization of vinyl acetate and butyl acrylate (VAc/BuA) (85:15) initiated by thermal initiators ammonium persulfate (APS) and potassium persulfate (PPS) at 70°C in the presence of nonylphenol ethoxylates of varying chain lengths (NP‐n) and acrylamide partially polymerized (Amol) was investigated. VAc‐BuA copolymer latexes were synthesized as two different series in the glass reactor, in the first serie was initiated by APS and PPS was used as initiator in the second serie. The influence of the counterions or initiators and chain lenghts of non‐ionic emulsifier on the properties of VAc‐BuA copolymer latexes were determined by measuring Brookfield viscosities, weight average molecular weights (M̄w), number average molecular weights (M̄w), molecular weight distribution and surface tension of latexes to air. The results of copolymer latexes indicated that their physicochemical properties increased with the increasing chain length of nonionic emulsifier for two initiators.
Stereoselective Cyclopolymerization of Diynes: Smart Materials for Electronics and Sensors
Authors: Krause Jens O. , Wang Dongren , Anders Udo , Weberskirch Ralf , Zarka M. Tobias , Nuyken Oskar , Jäger Claus , Haarer Dietrich , Buchmeiser Michael R.
Published: November 2004

A series of heptadiynes was cyclopolymerized by Schrock initiators to produce poly(ene)s exclusively based on one single repetitive unit, i.e. 1,2‐cyclopent‐2‐enylenvinylenes. Polymers containing virtually solely 1,2‐cyclopent‐2‐enylenvinylene units were obtained by various routes, e.g. by low‐temperature‐initiated cyclopolymerization of diethyldipropargyl malonate (DEDPM). A chiral poly(ene) was prepared from 4‐(ethoxycarbonyl)‐4‐(1S, 2R, 5S)‐(+)‐menthoxycarbonyl‐1,6‐heptadiyne (ECMHD) to determine the configuration of the double bonds and the tacticity of the poly(ene) backbone. Poly(ECMHD) consisted of >96% 5‐membered rings and possessed a tactic, alternating cis‐trans structure. Alternatively, poly(DEDPM) exclusively based on 1,2‐(cyclopent‐1‐enylene)vinylene units was prepared using MoCl5‐n‐Bu4Sn‐EtOH‐quinuclidine (1:1:5:1) and MoOCl4‐n‐Bu4Sn‐EtOH‐quinuclidine (1:1:2:1). The initiator efficiency of MoOCl4‐n‐Bu4Sn‐EtOH‐quinuclidine (1:1:2:1) was as high as 91%, the highest value ever reported for such systems. Multistage polymerizations of DEDPM indicated for both initiator systems that the catalytic species were active for at least 6 hours in the presence of monomer yet did not fulfill the criteria of a truly living polymerization. Finally, a new modification of the Grubbs‐Hoveyda catalyst, Ru(CF3COO)2(CH‐2‐(2,4,5‐(MeO)3‐C6H3)(SIMes) (SIMes=1,3‐dimesityl‐4,5‐dihydroimidazol‐2‐ylidene) allowed the first ruthenium alkylidene‐catalyzed living cyclopolymerization of DEDPM. The different initiators, their properties, the resulting polymerization systems as well as the physical properties of the resulting poly(ene)s are summarized.
Polymer Chain Dynamics Predicted by n‐Renormalized Rouse Models: Numerical Studies
Authors: Kroutieva Margarita , Fatkullin Nail , Kimmich Rainer
Published: November 2004

Features of the renormalized and twice renormalized Rouse models were examined numerically. Based on numerical evaluations of the generalized Langevin equation in renormalization approaches, nonexponential normal mode autocorrelation functions were derived, that can be described over two orders of magnitude by stretched exponential functions. The mode number dependence of the stretching parameter was evaluated. The consequences of the nonexponential correlation functions on dynamical properties are discussed. As a basis for predictions for the behavior of diffusion and spin‐lattice relaxation dispersion, the time dependence of the mean‐squared segment displacement and of the autocorrelation function of the segment tangential vector, respectively, were obtained taking into account finite chain lengths.
Molecular Dynamics Simulations of the First Steps of the Formation of Polysiloxane Layers at a Zinc Oxide Surface
Authors: Kornherr Andreas , Hansal Selma , Hansal Wolfgang E.G. , Nauer Gerhard E. , Zifferer Gerhard
Published: November 2004

Three different dissolved silane molecules adsorbed at a polar ZnO surface (000&1macr;) are studied by means of constant temperature molecular dynamics simulations. The adsorbed single silane molecules exhibit a different behavior depending on the chemical nature of their tail. For octyltrihydroxysilane molecules with their rather unpolar tail an orthogonal orientation at the polar metal oxide surface is statistically favored with all three polar hydroxide groups of the head being in contact with the polar ZnO surface and the unpolar tail remaining in the isopropanol phase. On the contrary, due to their highly polar tail, aminopropyltrihydroxysilane molecules show a more or less parallel orientation at the surface. Apart from some minor fluctuations two hydroxide groups as well as the amino group of the tail are in contact with the surface. The behavior of the thiolpropyltrihydroxysilane molecules is somehow located in between resulting in parallel as well as orthogonal orientations of the molecule at the surface. Though many of the results obtained for single adsorbed silane molecules can also be transferred to adsorbed silane molecules within whole layers a remarkable difference appears: Now even for aminopropyltrihydroxysilane molecules a mixture of parallel and orthogonal alignment of the molecules can be observed whereas some of the octyltrihydroxysilane molecules also show a parallel orientation.
Estimation of Slow Crack Growth Behavior in Polyethylene after Stepwise Isothermal Crystallization
Authors: Haager Markus , Pinter Gerald , Lang Reinhold W.
Published: November 2004

The use of analytical methods to estimate the SCG resistance of PE pipe materials has been suggested due to the fact that the slow crack growth (SCG) behavior of polyethylene (PE) is governed by structural parameters such as molecular weight and side chains. In the research project presented here, the molecular structure of several commercially available polyethylene‐high density (PE‐HD) materials was analyzed using a modified stepwise isothermal segregation (SIS) technique and compared with results from fracture mechanics experiments. A good correlation between the SIS results and SCG rates was found. It turned out that the modified SIS technique is a fast and simple method and could be used to assess SCG resistance in PE.
Reply: Sex and tremor location: Similarities between essential tremor and cervical dystonia
Authors: Louis Elan , Hardesty David E. , Maraganore Demetrius M. , Matsumoto Joseph Y.
Published: November 2004

The original letter to which this reply referrs has been published in Movement Disorders.
Sex and tremor location: Similarities between essential tremor and cervical dystonia
Authors: Duane Drake D.
Published: November 2004

A reply to this letter has been published in Movement Disorders .
A concise quaternion geometry of rotations
Authors: Meister L. , Schaeben H.
Published: November 2004

This communication compiles propositions concerning the spherical geometry of rotations when represented by unit quaternions. The propositions are thought to establish a two‐way correspondence between geometrical objects in the space of real unit quaternions representing rotations and geometrical objects constituted by directions in the three‐dimensional space subjected to these rotations. In this way a purely geometrical proof of the spherical Ásgeirsson's mean value theorem and a geometrical interpretation of integrals related to the spherical Radon transform of a probability density functions of unit quaternions are accomplished. Copyright © 2004 John Wiley & Sons, Ltd.
In vivo MRI of embryonic stem cells in a mouse model of myocardial infarction
Authors: Himes Nathan , Min Jian‐Yong , Lee Rebecca , Brown Courtney , Shea Jessica , Huang Xuling , Xiao Yong‐Fu , Morgan James P. , Burstein Deborah , Oettgen Peter
Published: November 2004

The therapeutic potential of administering stem cells to promote angiogenesis and myocardial tissue regeneration after infarction has recently been demonstrated. Given the advantages of using embryonic stem cells and mouse models of myocardial infarction for furthering the development of this therapeutic approach, the purpose of this study was to determine if embryonic stem cells could be loaded with superparamagnetic iron oxide (SPIO) particles and imaged in a mouse model of myocardial infarction over time using MRI. Mouse embryonic stem cells were labeled with SPIO particles. When incubated with 11.2, 22.4, and 44.8 μg Fe/ml of SPIO particles, cells took up increasing amounts of iron oxide. Embryonic stem cells loaded with SPIO compared to unlabeled cells had similar viability and proliferation profiles for up to 14 days. Free SPIO injected into infarcted myocardium was not observable within 12 hr after injection. After injection of three 10‐μl aliquots of 107 SPIO‐loaded cells/ml into infarcted myocardium, MRI demonstrated that the mouse embryonic stem cells were observable and could be seen for at least 5 weeks after injection. These findings support the ability of MRI to test the long‐term therapeutic potential of embryonic stem cells in small animals in the setting of myocardial infarction. Magn Reson Med 52:1214–1219, 2004. © 2004 Wiley‐Liss, Inc.
Estimating the arterial input function using two reference tissues in dynamic contrast‐enhanced MRI studies: Fundamental concepts and simulations
Authors: Yang Cheng , Karczmar Gregory S. , Medved Milica , Stadler Walter M.
Published: November 2004

In dynamic contrast‐enhanced MRI (DCE‐MRI) studies, an accurate knowledge of the arterial contrast agent concentration as a function of time is crucial for the estimation of kinetic parameters. In this work, a novel method for estimating the arterial input function (AIF) based on the contrast agent concentration‐vs.‐time curves in two different reference tissues is described. It is assumed that the AIFs of the two tissues have the same shape, and that simple models with two or more compartments, and unknown kinetic parameters, can describe their tracer concentration‐vs.‐time curves. Based on the principle of self‐consistency, one can relate the two tracer concentration‐vs.‐time curves to estimate their common underlining AIF, together with the kinetic parameters of the two tissues. In practice, the measured concentration‐vs.‐time curves have noise, and the AIFs of the two tissues are not exactly the same due to different dispersion effects. These factors will produce errors in the AIF estimate. Simulation studies show that despite the two error sources, the double‐reference‐tissue method provides reliable estimates of the AIF. Magn Reson Med 52:1110–1117, 2004. © 2004 Wiley‐Liss, Inc.
On the nature of the NAA diffusion attenuated MR signal in the central nervous system
Authors: Kroenke Christopher D. , Ackerman Joseph J.H. , Yablonskiy Dmitriy A.
Published: November 2004

In the brain, on a macroscopic scale, diffusion of the intraneuronal constituent N‐acetyl‐L‐aspartate (NAA) appears to be isotropic. In contrast, on a microscopic scale, NAA diffusion is likely highly anisotropic, with displacements perpendicular to neuronal fibers being markedly hindered, and parallel displacements less so. In this report we first substantiate that local anisotropy influences NAA diffusion in vivo by observing differing diffusivities parallel and perpendicular to human corpus callosum axonal fibers. We then extend our measurements to large voxels within rat brains. As expected, the macroscopic apparent diffusion coefficient (ADC) of NAA is practically isotropic due to averaging of the numerous and diverse fiber orientations. We demonstrate that the substantially non‐monoexponential diffusion‐mediated MR signal decay vs. b value can be quantitatively explained by a theoretical model of NAA confined to an ensemble of differently oriented neuronal fibers. On the microscopic scale, NAA diffusion is found to be strongly anisotropic, with displacements occurring almost exclusively parallel to the local fiber axis. This parallel diffusivity, ADC‖, is 0.36 ± 0.01 μm2/ms, and ADC⟂ is essentially zero. From ADC‖ the apparent viscosity of the neuron cytoplasm is estimated to be twice as large as that of a temperature‐matched dilute aqueous solution. Magn Reson Med 52:1052–1059, 2004. © 2004 Wiley‐Liss, Inc.
Bandwidth‐modulated adiabatic RF pulses for uniform selective saturation and inversion
Authors: Warnking Jan M. , Pike G. Bruce
Published: November 2004

Radiofrequency (RF) inversion and saturation pulses with extremely high spatial selectivity and uniform profiles are a requirement for numerous MR techniques, such as pulsed arterial spin labeling and outer volume suppression. Adiabatic pulses used for inversion of longitudinal magnetization are ubiquitous, but the superior selectivity of adiabatic full passages has not been widely exploited for saturation because a simple way of calibrating the amplitude of these subadiabatic pulses is lacking. An analytically derived calibration equation is presented, applicable to a large class of pulses including the hyperbolic secant (HS) pulse and allowing the determination of the precise amplitude required to achieve any effective flip angle. The properties of this calibration are examined, and a highly selective and homogeneous HS saturation pulse is demonstrated. Based on this calibration a new class of RF pulses is developed. These bandwidth‐modulated adiabatic selective saturation and inversion (BASSI) RF pulses afford optimal amplitude modulation, achieving uniform profiles at any effective flip angle. BASSI pulses are compared to existing gradient modulated adiabatic pulses in simulations and phantom experiments and shown to be superior in terms of selectivity and homogeneity, while requiring less RF energy. An application of BASSI pulses to pulsed arterial spin labeling is shown. Magn Reson Med 52:1190–1199, 2004. © 2004 Wiley‐Liss, Inc.
Parallel imaging performance as a function of field strength—An experimental investigation using electrodynamic scaling
Authors: Wiesinger Florian , Van de Moortele Pierre‐Francois , Adriany Gregor , De Zanche Nicola , Ugurbil Kamil , Pruessmann Klaas P.
Published: November 2004

In this work, the dependence of parallel MRI performance on main magnetic field strength is experimentally investigated. Using the general framework of electrodynamic scaling, the B0‐dependent behavior of the relevant radiofrequency fields at a single physical field strength of 7 T is studied. In the chosen implementation this is accomplished by adjusting the permittivity and conductivity of a homogeneous spherical phantom. With different mixing ratios of decane, ethanol, purified water, N‐methylformamide, and sodium chloride, field strengths in the range of 1.5 to 11.5 T are mimicked. Based on sensitivity maps of an eight‐coil receiver array, the field‐dependent performance of parallel imaging is assessed in terms of the geometry factor g, which reflects noise enhancement in parallel imaging reconstruction. At low field strengths the SNR penalty was nearly independent of B0 and favorably low for 1D reduction factors up to between 3 and 4. At higher field strengths the transition between favorable and prohibitive parallel imaging conditions was found to shift toward higher feasible reduction factors. These findings are in good agreement with previous theoretical predictions. From this agreement it is concluded that parallel MRI at high B0 benefits specifically from onsetting far‐field behavior of the involved radiofrequency fields. Magn Reson Med 52:953–964, 2004. © 2004 Wiley‐Liss, Inc.
Activity patterns of wrist extensor muscles during wrist extensions and deviations
Authors: Finsen L. , Søgaard K. , Graven‐Nielsen T. , Christensen H.
Published: November 2004

Wrist extensor muscles are prone to certain focal musculoskeletal disorders for which the activation pattern of the extensor carpi radialis (ECR) and ulnaris (ECU) muscles may be important risk factors. Surface and intramuscular EMG of these muscles were recorded during isometric low‐force wrist extension in semipronation and pronation as well as for ulnar/radial deviation, and were analyzed using root mean square (RMS) and decomposition methods. Despite shorter ECR length at semipronation, higher amplitudes of intramuscular EMG and of motor unit action potentials (MUAPs) were found in pronation than in semipronation. However, these changes were not detectable in the surface EMG. Higher ECR activity levels were also found during wrist extension compared to ulnar/radial deviation, and differences in the motor unit (MU) properties were found during ulnar deviation compared to radial deviation and extension. Remarkably, the MUAPs of ECR were almost twice as large as those of the ECU. Overall, the ECR muscle did not respond as predicted from biomechanical considerations, and in general activity level was higher than expected. This may partly explain why the tendon of the ECR often is associated with lateral epicondylitis. Muscle Nerve, 2005
The effect of crowd density on the expected number of casualties in a suicide attack
Authors: Kress Moshe
Published: November 2004

Utilizing elementary geometric and probability considerations, we estimate the effect of crowd blocking in suicide bombing events. It is shown that the effect is quite significant. Beyond a certain threshold, the expected number of casualties decreases with the number of people in the arena. The numerical results of our model are consistent with casualty data from suicide bombing events in Israel. Some operational insights are discussed. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005.
The utility of superparamagnetic contrast agents in MRI: theoretical consideration and applications in the cardiovascular system
Authors: Bjørnerud Atle , Johansson Lars
Published: November 2004

This review will discuss the in vivo physical chemical relaxation properties of superparamagnetic iron oxide particles. Various parameters such as size, magnetization, compartmentalization and water exchange effects and how these alter the behavior of the iron oxide particles in an in vitro vs an in vivo situation with special reference to the cardiovascular system will be exemplified. Furthermore, applications using iron oxide particles for vascular, perfusion and viability imaging as well as assessment of the inflammatory status of a given tissue will be discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Applications of ultrasmall superparamagnetic iron oxide contrast agents in the MR study of animal models
Authors: Wu Ed X. , Tang Haiying , Jensen Jens H.
Published: November 2004

Ultrasmall superparamagnetic iron oxide nanoparticles have been widely used during the past decade as MR intravascular contrast agents in the study of animal models. Such agents enhance both T1 and T2/T2* relaxation, although for animal studies it is the later type of enhancement that is most commonly exploited. Their strong microscopic intravascular susceptibility effect enables the local blood volume distribution to be mapped in various organs. High spatial resolution and sensitivity can be achieved, because the long half‐life of these agents in blood, combined with anesthetization, permits steady‐state measurements over extended periods. This capability has been utilized to study the cerebrovascular blood volume distributions and their changes in normal, activated, pathologic and pharmacologically or genetically modified states, particularly in rodent animal models. It has also been applied to study blood volume changes in other tissues, such as the myocardium. The relaxation rate shifts ΔR2 and ΔR2* induced by iron oxide agents may differ depending on certain morphological characteristics of the microvascular network, and sensitive ΔR2 and ΔR2* mapping can potentially provide, in addition to blood volume, measurement of other important microvascular parameters such as blood vessel density and size. This work aims to review the applications of ultrasmall superparamagnetic iron oxide contrast agents in MR animal studies, with an emphasis on the investigation of microvascular parameters. Copyright © 2004 John Wiley & Sons, Ltd.
Iron‐containing nodules of cirrhosis
Authors: Zhang Jingbo , Krinsky Glenn A.
Published: November 2004

In the absence of genetic hemochromatosis and systemic hemosiderosis, patients with cirrhosis can accumulate focal iron within regenerative or dysplastic hepatic nodules, commonly referred to as ‘siderotic nodules’. Siderotic dysplastic nodules are premalignant lesions while siderotic regenerative nodules are a marker for severe viral or alcoholic cirrhosis. The relationship of hepatic iron deposition to hepatic cirrhosis and neoplasia has not been fully clarified. This article will review the current literature regarding selective iron accumulation in siderotic nodules in chronic liver disease, followed by a discussion of current MR imaging techniques for detection and characterization of these nodules. Copyright © 2004 John Wiley & Sons, Ltd.
Treatment of material discontinuity in two meshless local Petrov–Galerkin (MLPG) formulations of axisymmetric transient heat conduction
Authors: Batra R. C. , Porfiri M. , Spinello D.
Published: November 2004

We use two meshless local Petrov–Galerkin (MLPG) formulations to analyse heat conduction in a bimetallic circular disk. The continuity of the normal component of the heat flux at the interface between two materials is satisfied either by the method of Lagrange multipliers or by using a jump function. The convergence of the H0 and H1 error norms for the four numerical solutions with an increase in the number of equally spaced nodes and in the number of quadrature points is scrutinized. With an increase in the number of uniformly spaced nodes, the two error norms decrease monotonically for the MLPG5 formulation but are essentially unchanged for the MLPG1 formulation. To our knowledge, this is the first study comparing the performance of the two methods of modelling a discontinuity in the gradient of a field variable at the interface between two different materials. Copyright © 2004 John Wiley & Sons, Ltd.