bluuebunny/crossref_metadata_2025 huggingface dataset:
A Photoactive Molecular Triad as a Nanoscale Power Supply for a Supramolecular Machine
Authors: Saha Sourav , Johansson Erik , Flood Amar H. , Tseng Hsian‐Rong , Zink Jeffrey I. , Stoddart J. Fraser
Published: August 2005

A tetrathiafulvalene–porphyrin–fullerene (TTF–P–C60) molecular triad, which generates electrical current by harnessing light energy when self‐assembled onto gold electrodes, has been developed. The triad, composed of three unique electroactive components, namely, 1) an electron‐donating TTF unit, 2) a chromophoric porphyrin unit, and 3) an electron‐accepting C60unit, has been synthesized in a modular fashion. A disulfide‐based anchoring group was tagged to the TTF end of the molecule in order to allow its self‐assembly on gold surfaces. The surface coverage by the triad in a self‐assembled monolayer (SAM) was estimated to be 1.4 nm2per molecule, a density which is consistent with hexagonal close‐packing of the spherical C60component (diameter ∼1 nm). In a closed electronic circuit, a triad‐SAM functionalized working‐electrode generates a switchable photocurrent of ∼1.5 μA cm−2when irradiated with a 413 nm Kr‐ion laser, a wavelength which is close to the porphyrin chromophore's absorption maximum peak at 420 nm. The electrical energy generated by the triad at the expense of the light energy is ultimately exploited to drive a supramolecular machine in the form of a [2]pseudorotaxane comprised of a π‐electron‐deficient tetracationic cyclobis(paraquat‐p‐phenylene) (CBPQT4+) cyclophane and a π‐electron‐rich 1,5‐bis[(2‐hydroxyethoxy) ethoxy]naphthalene (BHEEN) thread. The redox‐induced dethreading of the CBPQT4+cyclophane from the BHEEN thread can be monitored by measuring the increase in the fluorescence intensity of the BHEEN unit. A gradual increase in the fluorescence intensity of the BHEEN unit concomitant with the photocurrent generation, even at a potential (0 V) much lower than that required (−300 mV) for the direct reduction of the CBPQT4+unit, confirms that the dethreading process is driven by the photocurrent generated by the triad‐SAM.
Interplay between Intra‐ and Interligand Charge Transfer with Variation of the Axial N‐Heterocyclic Ligand in Osmium(II) Pyridylpyrazolate Complexes: Extensive Color Tuning by Phosphorescent Solvatochromism
Authors: Li Shih‐Wen , Cheng Yi‐Ming , Yeh Yu‐Shan , Hsu Cheng‐Chih , Chou Pi‐Tai , Peng Shie‐Ming , Lee Gene‐Hsiang , Tung Yung‐Liang , Wu Pei‐Chi , Chi Yun , Wu Fang‐Iy , Shu Ching‐Fong
Published: August 2005

The rational design and syntheses of a new series of OsII complexes with formula [Os(fppz)2(CO)(L)] (1: L=4‐dimethylaminopyridine; 2: L=pyridine; 3: L=4,4′‐bipyridine; 4: L=pyridazine; 5: L=4‐cyanopyridine), bearing two (2‐pyridyl)pyrazolate ligands (fppz) together with one carbonyl and one N‐heterocyclic ligand at the axial positions are reported. Single‐crystal X‐ray diffraction studies of, for example, 2 reveal a distorted octahedral geometry in which both fppz ligands reside in the equatorial plane with a trans configuration and adopt a bent arrangement at the metal center with a dihedral angle of ∼23°, while the carbonyl and pyridine ligands are located at the axial positions. Variation of the axial N‐heterocyclic ligand leads to remarkable changes in the photophysical properties as the energy gap and hence the phosphorescence peak wavelength can be tuned. For complexes 1 and 2 the solvent‐polarity‐independent phosphorescence originates from a combination of intraligand 3π–π* (3ILCT) and metal‐to‐ligand charge transfer transitions (3MLCT). In sharp contrast, as supported by cyclic voltammetry measurements and theoretical calculations, complexes 3–‐5 exhibit mainly ligand‐to‐ligand charge transfer (LLCT) transitions, resulting in a large dipolar change. The phosphorescence of complexes 3–‐5 thus exhibits a strong dependence on the polarity of the solvent, being shifted for example, from 560 (in C6H12) to 665 nm (in CH3CN) and from 603 (in C6H12) to 710 nm (in CH3CN) for complexes 3 and 5, respectively. The results clearly demonstrate that a simple, straightforward derivatization of the axial N‐heterocyclic ligand drastically alters the excitation properties per se from intraligand charge transfer (ILCT) to LLCT transitions. The latter exhibit remarkable LLCT phosphorescence solvatochromism so that a broad range of color tunability can be achieved.
Spectral interpolation errors
Authors: Sándor N. , Ondró T. , Schanda J.
Published: August 2005

Several CIE Technical Committees discussed the advantages and disadvantages of different spectral interpolation methods during the past years. Linear, Lagrange, cubic spline, and Sprague methods were under discussion. We have investigated the colorimetric differences caused by using the different interpolation methods, and showed that Lagrange, cubic spline, and Sprague methods provide very similar results for most well‐behaved spectra. As a further result, we found that the 5‐nm sampling and using the 5 nm tables of the CIE Technical Report “Colorimetry” is almost as good as an interpolation to 1‐nm sampling and colorimetric calculation using the 1‐nm tables of the CIE colorimetric standards. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 348–353, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.
Testing the behavior for metamerism of the new deviate observer (JF‐DO)
Authors: Martínez J. A. , Vega F. J. , Díaz J. A. , Pérez‐Ocón F. , Jiménez J. R.
Published: August 2005

Recently,in our laboratories, a set of color‐matching functions (cmfs) has been formulated for small fields by using two groups of real observers: JAM, MM, CF and AY, JR, MR, JL, JA, FP. The measurements of these cmfs have been made using different experimental devices and methods and it has enabled us to propose a New Deviate Observer for small fields (JF‐DO). This new JF‐DO was derived from the average observer of our nine real observers, following the technique used by the CIE to establish the Standard Deviate Observer (CIE‐1989 SDO), which was established for fields of 10°, despite the CIE's assumption that it can be applied to smaller fields. In the present work, we report experimental results of the JF‐DO using metameric reflectances in comparison to the CIE‐1931 Standard Observer and to the CIE‐1989 SDO. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 363–370, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.
Intermolecular Electronic Excitation Transfer in a Confined Space: A First‐Principles Study
Authors: Fois Ettore , Gamba Aldo , Medici Cinzia , Tabacchi Gloria
Published: August 2005

The process of intermolecular electronic excitation transfer (EET) in a monodimensional supramolecular arrangement of molecules in confined space has been modelled and investigated by means of first‐principles molecular dynamics simulations. The chosen model system consists of a wire of chlorine molecules hosted in the noncrossing channels of the zeolite bikitaite. The time evolution of the system in its first excited singlet state has been described by the restricted open shell Kohn–Sham formalism. Simulation results have highlighted that excitation, initially localized on a guest molecule, is transferred to an adjacent moiety in the molecular wire on the picosecond scale via a collision‐induced Dexter‐type short range EET. Analysis of the modifications of the electronic structure of the system brought about by EET has given insight into the microscopic details of the process.
Dual‐Scale Modeling of Benzene Adsorption onto Ni(111) and Au(111) Surfaces in Explicit Water
Authors: Schravendijk Pim , van der Vegt Nico , Delle Site Luigi , Kremer Kurt
Published: August 2005

We present a multiscale modeling approach for studying interactions of organic molecules with metal surfaces in explicit water. The approach is based on combining adsorption energies of isolated molecules on transition metal surfaces calculated by ab initio density functional methods and classical molecular dynamics simulations using atomistically detailed force fields. The interaction of benzene with Ni(111) and Au(111) surfaces was studied. It is shown that a strong affinity of water for the hydrophilic surfaces makes benzene adsorption on Au thermodynamically unfavorable, while on Ni there is no preference. The work presented here serves as a first step in modeling the interactions of larger organic molecules with metal surfaces.
Density of Configurational States from First‐Principles Calculations: The Phase Diagram of Al–Na Surface Alloys
Authors: Borg Mikael , Stampfl Catherine , Mikkelsen Anders , Gustafson Johan , Lundgren Edvin , Scheffler Matthias , Andersen Jesper N.
Published: August 2005

The structural phases of AlxNa1−x surface alloys have been investigated theoretically and experimentally. We describe the system using a lattice‐gas Hamiltonian, determined from density functional theory, together with Monte Carlo (MC) calculations. The obtained phase diagram reproduces the experiment on a quantitative level. From calculation of the (configurational) density of states by the recently introduced Wang–Landau MC algorithm, we derive thermodynamic quantities, such as the free energy and entropy, which are not directly accessible from conventional MC simulations. We accurately reproduce the stoichiometry, as well as the temperature at which an order–disorder phase transition occurs, and demonstrate the crucial role, and magnitude, of the configurational entropy.
Car–Parrinello Molecular Dynamics on Massively Parallel Computers
Authors: Hutter Jürg , Curioni Alessandro
Published: August 2005

Into a parallel dimension: The Car–Parrinello molecular dynamics (CPMD) method is shown to be highly suited to modern computer architectures, such as clustered shared‐memory parallel servers and ultra‐dense massively parallel computers. Different parallelization strategies are reviewed to elucidate the most efficient application of the CPMD code.
Correlation analysis of coupled fitness landscapes
Authors: Hordijk Wim , Kauffman Stuart A.
Published: August 2005

The correlation structure of fitness landscapes is a much used measure to characterize and classify various types of landscapes. However, analyzing the correlation structure of fitness landscapes has so far been restricted to static landscapes only. Here, we investigate the correlation structure of coupled, or dynamic, fitness landscapes. Using the NKC model of coevolution, we apply a correlation analysis on various instances of this model and present the results. One of the main goals of this article is thus to show that a previously introduced correlation analysis can be successfully extended to coupled fitness landscapes. Furthermore, our analysis shows that this provides meaningful and interesting results that can contribute to a better understanding of coevolution in general. © 2005 Wiley Periodicals, Inc. Complexity 10: 41–49, 2005
Improved Understanding of the Nonlinear Properties of Ionization Instabilities in Plasmas
Authors: Bruhn B. , Koch B.‐P. , Wilke C.
Published: August 2005

In this paper we review our experimental and theoretical investigations of ionization waves in a low‐pressure discharge of neon. The main results are connected with the transition between regular and irregular wave motions. The experimental observed stability boundaries can well be understood within the hydrodynamic model. The point is the explanation of the experimentally observed mode transitions by means of a quintic amplitude equation of the Ginzburg‐Landau type. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis and Kinetics of Transient Species in Electrode Near Plasma and Plasma Boundary Sheath of RF Plasmas in Molecular Gases
Authors: Geigl M. , Peters S. , Gabriel O. , Krames B. , Meichsner J.
Published: August 2005

Modern diagnostic methods are applied for investigation of spatial and temporal behaviour of selected reactive species in oxygen and fluorocarbon rf plasmas. Comprehensive investigations of the spatial distribution of atomic oxygen were done by means of two‐photon absorption laser induced fluorescence spectroscopy. Exemplarily, axial and radial O‐concentrations are shown for an asymmetric capacitively coupled rf plasma in pure oxygen. The time resolved threshold ionization mass spectrometry was applied for investigation of small fluorocarbon radicals. In pulsed CF4/H2 rf plasma the concentrations of the extracted radicals CF2, CF3, C2F5 as well as the intermediate product C2F4 in the plasma on and off phase are presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interaction of Partially Ionized Plasmas with Electromagnetic Fields
Authors: Kremp D. , Bornath Th. , Bonitz M. , Semkat D. , Schlanges M.
Published: August 2005

The interaction of partially ionized plasmas with an electromagnetic field is investigated using quantum statistical methods. A general statistical expression for the current density of a plasma in an electromagnetic field is presented and considered in the linear response and the high field regime. Expressions for the collisional absorption (inverse bremsstrahlung) are derived and discussed. In addition, results of molecular dynamics simulations are shown. Further, partially ionized plasmas are considered. Plasma Bloch equations for the description of bound–free transitions are given and the absorption coefficient as well as rate coefficients for multiphoton ionization are presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermodynamic Properties of Dense Hydrogen
Authors: Schlanges M. , Bezkrovniy V. , Vorberger J. , Kremp D. , Kraeft W. D.
Published: August 2005

The equation of state of hydrogen is determined theoretically in the limits of the fully ionized plasma and the neutral reacting gas mixture. Analytical results are presented for the fully ionized state and compared to data from quantum simulations. The dense hydrogen gas is dealt with using Reaction Ensemble Monte Carlo and hypernetted chain techniques. The results are compared to other theoretical methods and to experimental findings. Finally, Reaction Ensemble Monte Carlo data are combined with Path Integral Monte Carlo results to give a Hugoniot curve covering the entire pressure range. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic Structure Factor of Dusty and Low‐Dimensional Plasmas
Authors: Wierling A. , Reinholz H. , Röpke G. , Adams J.
Published: August 2005

Experiences investigating the dynamic structure factor of dense plasmas are applied to complex plasmas, in particular to dusty plasmas and dimensionally reduced plasmas. Using generalized linear response theory, the dynamical structure factor is obtained from a density response function expressed in terms of equilibrium correlation function. Corrections beyond the RPA approximation are taken into account by evaluating local‐field corrections within the recurrance method. Results for the dynamic structure factor of a Yukawa plasma is compared with molecular dynamics calculations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First Principle Thermodynamic and Dynamic Simulations for Dense Quantum Plasmas
Authors: Bonitz M. , Filinov A. , Golubnychiy V. O. , Bornath Th. , Kraeft W. D.
Published: August 2005

We present a detailed analysis of temperature‐dependent effective quantum pair potentials. These potentials are derived from first‐principle path integral Monte Carlo simulations and are accurate even at strong coupling and partial ionization. They can be efficiently used in molecular‐dynamics (MD) simulations to obtain accurate thermodynamic and dynamic properties of strongly coupled hydrogen down to the temperatures of about 60 000 K. Furthermore, using spin‐dependent pair potentials, dynamic structure factors and spin‐density correlation functions were calculated for different values of coupling and degeneracy. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Isolation and characterization of the laure olfactory behavioral mutant in the zebrafish, Danio rerio
Authors: Vitebsky A. , Reyes R. , Sanderson M.J. , Michel W.C. , Whitlock K. E.
Published: August 2005

To initiate a genetic analysis of olfactory development and function in the zebrafish, Danio rerio, we developed a behavioral genetic screen for mutations affecting the olfactory sensory system. First, we characterized olfactory responses of wild‐type zebrafish to various odors. We found that 3‐day‐old juvenile zebrafish reacted to the amino acid L‐cysteine with an aversive behavioral response. We isolated one mutant, laure (lre), which showed no aversive behavioral response to L‐cysteine at 3 days of development, and carried out a preliminary characterization of this mutant's defects. We found that lre mutant fish were also defective in their response to L‐serine and L‐alanine, but not to taurocholic acid, as young adults. In addition, lre mutant fish had significantly fewer primary olfactory sensory neurons than normal, and the axons of these neurons did not form the characteristic axon termination pattern in the developing olfactory bulb. Nevertheless, the olfactory epithelium of lre mutant fish showed normal or near normal electrophysiological responses to several odorants. Our data suggest that the behavioral defects observed in the lre mutant result from the disruption of the developing olfactory sensory neurons and their axonal connections within the olfactory bulb. The isolation of the lre mutant shows that our behavior‐based screen represents a viable approach for carrying out a genetic dissection of olfactory behaviors in this vertebrate model system. Developmental Dynamics 234:229–242, 2005. © 2005 Wiley‐Liss, Inc.
Induction of apoptosis involving multiple pathways is a primary response to cyclin A1‐deficiency in male meiosis
Authors: Salazar Glicella , Joshi Ayesha , Liu Dong , Wei Hongquan , Persson Jenny Liao , Wolgemuth Debra J.
Published: August 2005

The meiotic arrest in male mice null for the cyclin A1 gene (Ccna1) was associated with apoptosis of spermatocytes. To determine whether the apoptosis in spermatocytes was triggered in response to the arrest at G2/M phase, as opposed to being a secondary response to overall disruption of spermatogenesis, we examined testes during the first wave of spermatogenesis by terminal deoxynucleotidyl transferase–mediated deoxyuridinetriphosphate nick end‐labeling (TUNEL) staining. We observed enhanced apoptosis coinciding with the arrest point in postnatal day 22 tubules, with no overt degeneration. Along with activation of caspase‐3, an increase in the levels and change of subcellular localization of Bax protein was observed in cyclin A1–deficient spermatocytes, which coincided with the detection of apoptosis. As p53 is implicated in the activation of Bax‐mediated cell death, we generated mice lacking both cyclin A1 and p53. Although the absence of p53 did not rescue the meiotic arrest, there was a decrease in the number of apoptotic cells in the double‐mutant testes. This finding suggested that p53 may be involved in the process by which the arrested germ cells are removed from the seminiferous tubules but that other pathways function as well to ensure removal of the arrested spermatocytes. Developmental Dynamics 234:114–123, 2005. © 2005 Wiley‐Liss, Inc.
The influence of natural antibody specificity on antigen immunogenicity
Authors: Benatuil Lorenzo , Kaye Joel , Rich Robert F. , Fishman Jay A. , Green William R. , Iacomini John
Published: August 2005

The natural antibody repertoire in humans, apes and Old World primates is distinct from the repertoire of all other placental mammals, and encodes antibodies specific for the carbohydrate epitope Galα1–3Galβ1–4GlcNAc‐R (αGal). Here, we examined whether conjugating antigens to the αGal epitope can augment their immunogenicity in α(1,3)galactosyltransferase knockout mice (GT0 mice) which, like humans, produce αGal‐specific antibodies. Immunization of GT0 mice with BSA conjugated to αGal (αGal‐BSA) led to significant production of anti‐BSA IgG antibodies without the need for adjuvant. This response was dependent on the presence of αGal‐reactive antibodies. Immunization of wild‐type mice with αGal‐BSA failed to induce an anti‐BSA response. The presence of αGal‐reactive antibodies also led to an increase in the T cell response to BSA following immunization with αGal‐BSA when compared with mice that received BSA alone, resulting in an increased frequency of IFN‐γ− and IL‐4‐producing BSA‐specific T cells. In addition, the ability to produce αGal‐reactive antibodies enhanced the cytotoxic T lymphocyte anti‐viral antigen response following vaccination with murine leukemia virus transformed cell lines that express αGal on their cell surface. Natural antibodies that bind αGal therefore play a key role in increasing the efficiency of priming to antigens decorated with αGal epitopes.
Early regulation of CD8 T cell alloreactivity by CD4+CD25– T cells in recipients of anti‐CD154 antibody and allogeneic BMT is followed by rapid peripheral deletion of donor‐reactive CD8+ T cells, precluding a role for sustained regulation
Authors: Fehr Thomas , Takeuchi Yasuo , Kurtz Josef , Wekerle Thomas , Sykes Megan
Published: August 2005

While acquisition of regulatory function by CD4+CD25– T cells has been reported following antigenic stimulation, “naturally occurring” regulatory CD4+ T cells (Treg) are believed to express CD25. We examined the mechanisms involved in peripheral CD8 T cell tolerance by induction of mixed chimerism using non‐myeloablative conditioning with low‐dose (3 Gy) total body irradiation and anti‐CD154 antibody. Recipient CD4+ T cells were initially required for the induction of CD8 cell tolerance, but were not needed beyond 2 weeks. Depletion of CD25+ Treg prior to bone marrow transplantation and blockade of IL‐2 with neutralizing antibody did not impede tolerance induction. Tolerance was dependent on CTLA4, but not on IFN‐γ. In C57BL/6 mice containing a fraction of 2C TCR transgenic CD8+ T cells, which recognize the MHC class I alloantigen Ld, induction of chimerism with Ld+, but not Ld–, bone marrow cells led to deletion of peripheral 2C+ CD8+ cells within 1 week in peripheral blood and spleen. Complete deletion required the presence of recipient CD4+ T cells. Thus, a novel, rapid form of regulation by CD4+CD25– T cells permits initial CD8 T cell tolerance in this model. Rapid peripheral deletion of donor‐specific CD8 T cells precludes an ongoing requirement for CD4 T cell‐mediated regulation.
Carbohydrates located on the top of the “cap” contribute to the adhesive and enzymatic functions of vascular adhesion protein‐1
Authors: Maula Sanna‐Mari , Salminen Tiina , Kaitaniemi Sam , Nymalm Yvonne , Smith David J. , Jalkanen Sirpa
Published: August 2005

Vascular adhesion protein 1 (VAP‐1) is an endothelial adhesion molecule with an enzymatic activity. It deaminates biogenic amines, resulting in the formation of aldehydes and hydrogen peroxide. During the enzymatic reaction a transient Schiff base is formed between endothelial VAP‐1 and its leukocytic ligand, and this interaction is important for lymphocyte adhesion. VAP‐1 monomer has six potential N‐linked, and three putative O‐linked glycosylation sites and an SSSS sequence potentially forming an attachment site for an adjacent O‐linked site. In this work we modeled the carbohydrate decorations on a structural model of VAP‐1, and studied which of those potential glycosylation sites are utilized, and whether those decorations accessible to a lymphocyte ligand are important in lymphocyte adhesion and enzymatic activity of VAP‐1. We show that, unlike the O‐linked attachment sites, all six N‐linked glycosylation sites are in use. Furthermore, mutation of the N‐linked attachment sites strategically located on the top of the molecule reduces lymphocyte adhesion in non‐static conditions, and enhances the catalytic activity of membrane‐bound human VAP‐1 in static conditions, suggesting that glycosylation regulates the functional properties of VAP‐1.
Surface modification of gold and quantum dot nanoparticles with chitosan for bioapplications
Authors: Tan Wee Beng , Zhang Yong
Published: August 2005

Gold (Au) and quantum dot (QD) nanoparticles, which have been extensively used in many fields, were encapsulated with a natural polymer, chitosan, to improve their biocompatibility. Characterization was performed using ultraviolet–visible, dynamic light scattering, atomic force microscopy, and transmission electron microscope analyses. It was found that a Au/chitosan ratio of 1:1 and smaller produced chitosan‐encapsulated Au nanoparticles of a sufficiently small size, and this result was then applied in the chitosan encapsulation of QDs. The biocompatibility of both types of nanoparticles was assessed in cell culture studies using HT29 human colon carcinoma and NIH 3T3 mouse fibroblast cells. MTT and trypan blue exclusion assays revealed that both chitosan‐encapsulated Au nanoparticles and QDs exhibited improved biocompatibility over their bare, nonencapsulated counterparts. Therefore, this study showed that chitosan could be used to encapsulate both Au nanoparticles and QDs in order to enhance their biocompatibility. The approaches developed in this study can also be extended to other nanoparticles for bioapplications as well. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Edge disjoint cycles through specified vertices
Authors: Goddyn Luis , Stacho Ladislav
Published: August 2005

We give a sufficient condition for a simple graph G to have k pairwise edge‐disjoint cycles, each of which contains a prescribed set W of vertices. The condition is that the induced subgraph G[W] be 2k‐connected, and that for any two vertices at distance two in G[W], at least one of the two has degree at least |V(G)|/2 + 2(k − 1) in G. This is a common generalization of special cases previously obtained by Bollobás/Brightwell (where k = 1) and Li (where W = V(G)). A key lemma is of independent interest. Let G be the complement of a bipartite graph with partite sets X, Y. If G is 2k connected, then G contains k Hamilton cycles that are pairwise edge‐disjoint except for edges in G[Y]. © 2005 Wiley Periodicals, Inc. J Graph Theory
Development and growth of long bones in European water frogs (Amphibia: Anura: Ranidae), with remarks on age determination
Authors: Rozenblut Beata , Ogielska Maria
Published: August 2005

Differentiation and development of long bones were studied in European water frogs: Rana lessonae, R. ridibunda, and R. esculenta. The study included premetamorphic larvae (Gosner Stage 40) to frogs that were 5 years old. Femora, metatarsal bones, and proximal phalanges of the hindlimb exhibit the same pattern of periosteal bone differentiation and the same pattern of growth. Longitudinal and radial growth of these bones was studied by examination of the diaphyses and epiphyses, particularly where the edge of periosteal bone is inserted into the epiphysis. The periosteum seems to be responsible for both longitudinal and radial growth. Investigation of the formation, length, and arrangement of lines of arrested growth reveals that the first line is present only in the middle 25–35% of the length of the diaphysis of an adult bone; therefore, only the central portion of the diaphysis should be used for age estimation in skeletochronological studies. Comparison of the shapes and histological structures of epiphyses in the femur, metatarsal bones, and phalanges revealed that epiphyseal cartilages are composed of an inner and outer part. The inner metaphyseal cartilage has distinct zones and plugs the end of the periosteal bone cylinder; its role in longitudinal growth is questioned. The outer epiphyseal cartilage is composed of articular cartilages proper, in addition to lateral articular cartilages. Differences in the symmetry of the lateral articular cartilages of distal epiphyses of the femur and toes may reflect adaptations to different kinds of movements at the knee and in the foot. J. Morphol. © 2005 Wiley‐Liss, Inc.
Astroglial cells in the central nervous system of the adult brown anole lizard, Anolis sagrei, revealed by intermediate filament immunohistochemistry
Authors: Lazzari Maurizio , Franceschini Valeria
Published: August 2005

We analyzed the distribution of intermediate filament molecular markers, glial fibrillary acidic protein (GFAP), and vimentin in the brain and spinal cord of the adult brown anole lizard, Anolis sagrei. The GFAP immunoreactivity is strong and the positive structures are basically represented by fibers of different lengths and thicknesses which are arranged in a regular radial pattern throughout the central nervous system. In the brain regions that have a thicker neural wall, the radial orientation is not so evident as in the thinner areas. These fibers emerge from radial ependymoglia (tanycytes) whose cell bodies are generally GFAP‐immunopositive. The glial fibers give rise to endfeet that are apposed to the subpial surface and to blood vessel walls. In the spinal cord, the optic tectum and the lateroventral regions of the mesencephalon and medulla oblongata, star‐shaped astrocytes coexist with radial structures. Vimentin‐immunoreactive structures are absent in the brain and spinal cord. In A. sagrei the immunohistochemical response of the astroglial intermediate filaments appears typical of a mature astroglial cell lineage, since they fundamentally express GFAP immunoreactivity. A Western‐blot analysis reveals a GFAP‐positive single band, common to the different nervous areas. This immunohistochemical study shows that the star‐shaped astrocytes have a different distribution in saurians and while the glial pattern of A. sagrei is more evolved than in urodeles it remains immature as compared with crocodilians, avians, and mammals. This condition suggests that reptiles represent a fundamental step in the phylogenetic evolution of the vertebrate glial cells. J. Morphol. © 2005 Wiley‐Liss, Inc.
Stable expression of EBERs in immortalized nasopharyngeal epithelial cells confers resistance to apoptotic stress
Authors: Wong Hing Lok , Wang Xianghong , Chang Raymond Chuen‐Chung , Jin Dong‐Yan , Feng Huichen , Wang Qi , Lo Kwok‐Wai , Huang Dolly P. , Yuen Po Wing , Takada Kenzo , Wong Yong Chuan , Tsao Sai Wah
Published: August 2005

Epstein–Barr virus (EBV) infection is closely associated with the development of nasopharyngeal carcinoma (NPC). The EBV‐encoded RNAs (EBERs) are the most abundant EBV transcripts (about 107 copies per cell) in EBV infected cells. However, the cellular function of EBER expression, particularly in nasopharyngeal epithelial cells, remains poorly understood. EBERs acquire secondary structures analogous to double‐stranded RNA (dsRNA) and may bind to the double‐stranded RNA‐dependent protein kinase (PKR) and interfere with its function. Activation of PKR involves autophosphorylation resulting in protein synthesis inhibition and cellular apoptosis. Induction of cellular apoptosis by activation of PKR may be an antiviral response adopted by virally infected cells. We have examined the functional properties of EBER expression in an immortalized nasopharyngeal epithelial cell line (NP69). Expression of EBERs was achieved by transfecting the NP69 cells with an EBER‐expressing plasmid, pESK10. The EBER‐expressing NP69 cells attained a higher growth rate compared to cells transfected with control plasmid (pcDNA3). However, the EBER‐expressing NP69 cells did not form colonies in soft agar and were non‐tumorigenic in nude mice. To investigate if EBERs may protect the nasopharyngeal epithelial cells from apoptotic insults, we treated the EBER‐expressing NP69 cells with a dsRNA analogue, poly(I).poly(C) (pIC), to activate PKR in cells and examined for their responses. Lower level of PKR phosphorylation and elevation of Bcl‐2 were observed in EBER‐expressing NP69 cells. In addition, other apoptotic markers including the cleaved forms of caspase‐3 and poly(ADP)ribose polymerase (PARP) were found to be lower in EBER‐expressing NP69 cells after treatment with pIC. Lower phosphorylation levels of p38 MAPK (mitogen‐activated protein kinase) and c‐jun were also observed in EBER‐expressing NP cells. Our results suggest that EBER expression may confer an apoptotic‐resistant phenotype in immortalized nasopharyngeal epithelial cells. © 2005 Wiley‐Liss, Inc.
Development of ultra short‐acting muscle relaxant agents: History, research strategies, and challenges
Authors: Gyermek Laszlo
Published: August 2005

Author has reviewed the literature and his own work related to the chemistry, pharmacology, and clinical aspects of new muscle relaxants. Emphasis has been placed on the basic science concepts and technologies (e.g. structure–activity relationships, nicotinic receptor pharmacology, and investigation of side effects) behind the development of rapidly and short acting nondepolarizing muscle relaxants. © 2005 Wiley Periodicals, Inc.
Simultaneous spin‐echo refocusing
Authors: Günther Matthias , Feinberg David A.
Published: August 2005

A new approach to spin‐echo imaging is presented in which the 180° RF pulse refocuses two or more spin‐echoes at different positions in the readout period. When simultaneous echo refocusing (SER) is implemented using multiple 180° pulses, an undesirable mixing of stimulated echoes and primary echoes from different slices can occur. A novel periodic gradient spoiler scheme eliminates this potential source of artifacts without spoiling the correctly timed stimulated echoes, which, similar to RARE (TSE) sequences, add coherently to the primary echoes. Comparisons show equivalent artifact elimination using phase cycling, periodic spoiling, and a previously developed spoiling scheme for non‐Carr–Purcell–Meiboom–Gill sequences. A comparison of head images at 1.5 T acquired with SER‐TSE and conventional TSE T1‐weighted sequences show no degradation in image quality nor SNR. T2‐weighted imaging is not achievable with the current implementation, but possible solutions are proposed. The proposed technique might prove especially beneficial at higher field strengths, where the reduced number of refocusing pulses for multislice SER‐TSE decreases RF power deposition. SER spin‐echo imaging offers an approach that is very different from low flip angle imaging to mitigate RF heating limitations in high‐field clinical imaging. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Fast spin‐echo for multiple mouse magnetic resonance phenotyping
Authors: Nieman Brian J. , Bock Nicholas A. , Bishop Johnathan , Sled John G. , Josette Chen X. , Mark Henkelman R.
Published: August 2005

High‐resolution magnetic resonance imaging is emerging as a powerful tool for phenotyping mice in biologic studies of genetic expression, development, and disease progression. In several applications, notably random mutagenesis trials, large cohorts of mice must be examined for abnormalities that may occur in any part of the body. In the aim of establishing a protocol for imaging multiple mice simultaneously in a standardized high‐throughput fashion, this study investigates variations of a three‐dimensional fast spin‐echo sequence that implements driven equilibrium, modified refocusing, and partial excitation pulses. Sequence variations are compared by simulated and experimental measurements in phantoms and mice. Results indicate that when using a short repetition time (TR ≤ T1) a sequence employing a partial excitation tip angle provides both improved signal and good T2 contrast compared with standard fast spin‐echo imaging. This sequence is used to simultaneously acquire four live mouse head images at 100 μm isotropic resolution with a scan time under 3 h at 7 T. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Simultaneous water and lipid suppression for in vivo brain spectroscopy in humans
Authors: Smith Mari A. , Gillen Joseph , McMahon Michael T. , Barker Peter B. , Golay Xavier
Published: August 2005

A method to achieve simultaneous water and lipid suppression is described. The key feature of the new dual suppression technique is the use of the well‐known hyperbolic secant (HS) waveform as a 90° saturation pulse. Two HS pulses with opposite frequency offsets are employed either sequentially or simultaneously to saturate resonance frequencies corresponding to water and lipid, while leaving the target spins untouched. The excitation bandwidth is controlled by the frequency sweep and offset of each pulse, while varying the pulse length controls the transition bandwidth. An example of the use of the dual saturation method in in vivo magnetic resonance spectroscopic imaging of the human brain is presented. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Broadband multicoil imaging using multiple demodulation hardware: A feasibility study
Authors: Lee Jin Hyung , Scott Greig C. , Pauly John M. , Nishimura Dwight G.
Published: August 2005

Multiple receiver‐coil data collection is an effective approach to reduce scan time. There are many parallel imaging techniques that reduce scan time using multiple receiver coils. One of these methods, partially parallel imaging with localized sensitivities (PILS), utilizes the localized sensitivity of each coil. The advantages of PILS over other parallel imaging methods include the simplicity of the algorithm, good signal‐to‐noise ratio (SNR) properties, and the fact that there is no additional complexity involved in applying the algorithm to arbitrary k‐space trajectories. This PILS method can be further improved to provide truly parallel broadband imaging with the use of multiple‐demodulation hardware. By customizing the demodulation based on each coil's location, the k‐space sampling rate can be chosen based on each coil's localized sensitivity region along the readout direction. A simulated demodulation of data from 2D Fourier transform (FT) and spiral trajectories is shown to demonstrate the method's feasibility. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Hemispherical gradient coils for magnetic resonance imaging
Authors: Green Dan , Leggett James , Bowtell Richard
Published: August 2005

Hemispherical gradient coils offer an open geometry that is well suited to imaging of the human brain. The windings of a hemispherical gradient coil are on average closer to the target region than those of a comparable cylindrical coil, and consequently hemispherical coils can produce higher efficiency at fixed inductance. The mathematical formalism needed for the design of hemispherical gradient coils is described here, including expressions relating the current distribution on the hemisphere to the magnetic field generated, as well as the stored energy and power dissipation. In addition, expressions for the torque experienced by the current distribution in the presence of the main magnetic field have been derived and used to develop an approach allowing the design of torque‐balanced, hemispherical transverse gradient coils. Hemispherical coil designs suitable for brain imaging are presented and shown to have improved performance compared with their cylindrical counterparts. Small, prototype, hemispherical z‐ and x‐gradient coils have been constructed and tested in phase‐mapping experiments at 3 T. The experimental results show good agreement with theoretical predictions, validating the mathematical expressions used in the coil design process. The formalism also allows the design of coils wound on a complete spherical surface, and the performance of such coils is additionally described here. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
T1, T2 relaxation and magnetization transfer in tissue at 3T
Authors: Stanisz Greg J. , Odrobina Ewa E. , Pun Joseph , Escaravage Michael , Graham Simon J. , Bronskill Michael J. , Henkelman R. Mark
Published: August 2005

T1, T2, and magnetization transfer (MT) measurements were performed in vitro at 3 T and 37°C on a variety of tissues: mouse liver, muscle, and heart; rat spinal cord and kidney; bovine optic nerve, cartilage, and white and gray matter; and human blood. The MR parameters were compared to those at 1.5 T. As expected, the T2 relaxation time constants and quantitative MT parameters (MT exchange rate, R, macromolecular pool fraction, M0B, and macromolecular T2 relaxation time, T2B) at 3 T were similar to those at 1.5 T. The T1 relaxation time values, however, for all measured tissues increased significantly with field strength. Consequently, the phenomenological MT parameter, magnetization transfer ratio, MTR, was lower by approximately 2 to 10%. Collectively, these results provide a useful reference for optimization of pulse sequence parameters for MRI at 3 T. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Biexponential parameterization of diffusion and T2 relaxation decay curves in a rat muscle edema model: Decay curve components and water compartments
Authors: Ababneh Zaid , Beloeil Helene , Berde Charles B. , Gambarota Giulio , Maier Stephan E. , Mulkern Robert V.
Published: August 2005

Quantitative T2 relaxation and diffusion imaging studies of a rat muscle edema model were performed in order to determine the effects of intra‐ and extracellular water compartmentation on the respective decay curves. The right hind paw of rats was injected with a carrageenan solution to generate edematous muscle. A Carr–Purcell–Meiboom–Gill (CPMG) imaging sequence was used to acquire T2 relaxation decay curves from both paws. A line scan diffusion imaging (LSDI) sequence was then used to acquire diffusion decay curves from the same paws over a wide b‐factor range. Measurements were made from both edematous muscle (EM) and control muscle (CM). The EM and CM T2 relaxation decay curves were best fit with biexponential functions. The fraction of the fast T2 component dropped dramatically from approximately 0.95 in CM to 0.45 in EM, consistent with a water compartmentation model in which the fast and slow T2 components reflect intra‐ and extracellular water, respectively. Both CM and EM diffusion decay curves required biexponential fitting functions, and the diffusion coefficients of the fast and slow components were substantially larger in EM than CM. The fraction of the fast diffusion component, however, was not radically altered between CM and EM conditions (0.84 versus 0.89 for CM versus EM). Assuming a model in which intra‐ and extracellular water compartments are responsible for the fast and slow T2‐decay components and for the slow and fast diffusion decay components, respectively, leads to fractional sizes of the diffusion components that are not supported by experiment. We conclude that intra‐ and extracellular water compartmentation is a reasonable interpretation for the two T2‐decay components in both CM and EM but that other factors, such as restricted diffusion and/or alternate forms of water compartmentation like surface versus volume water, most probably have profound influences on the precise shapes of the diffusion decay curves, a complete understanding of which will require significant theoretical work. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Magnetic resonance imaging of cardiomyocyte apoptosis with a novel magneto‐optical nanoparticle
Authors: Sosnovik David E. , Schellenberger Eyk A. , Nahrendorf Matthias , Novikov Mikhail S. , Matsui Takashi , Dai George , Reynolds Fred , Grazette Luanda , Rosenzweig Anthony , Weissleder Ralph , Josephson Lee
Published: August 2005

The ability to image cardiomyocyte apoptosis in vivo with high‐resolution MRI could facilitate the development of novel cardioprotective therapies. The sensitivity of the novel nanoparticle AnxCLIO‐Cy5.5 for cardiomyocyte apoptosis was thus compared in vitro to that of annexin V‐FITC and showed a high degree of colocalization. MRI was then performed, following transient coronary artery (LAD) occlusion, in five mice given AnxCLIO‐Cy5.5 and in four mice given an identical dose (2 mg Fe/kg) of CLIO‐Cy5.5. MR signal intensity and myocardial T2* were evaluated, in vivo, in hypokinetic regions of myocardium in the LAD distribution. Ex vivo fluorescence imaging was performed to confirm the in vivo findings. Myocardial T2* was significantly lower in the mice given AnxCLIO‐Cy5.5 (8.1 versus 13.2 ms, P < 0.01), and fluorescence target to background ratio was significantly higher (2.1 versus 1.1, P < 0.01). This study thus demonstrates the feasibility of obtaining high‐resolution MR images of cardiomyocyte apoptosis in vivo with the novel nanoparticle, AnxCLIO‐Cy5.5. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Solitary bone plasmocytoma of the spine in an adolescent
Authors: Dumesnil C. , Schneider P. , Dolgopolov I. , Radi S. , Leluyer B. , Vannier J.P.
Published: August 2005

Solitary plasmocytoma (SP) represent only about 5% of plasma cell neoplasia. Most patients have generalized disease, that is, multiple myeloma (MM). Solitary bone plasmocytoma (SBP) is a localized plasma cell tumor and is a very rare disease in young patients. We reported here, a case of SPB in a 14‐year‐old girl with a 10‐year disease‐free survival after an aggressive treatment. The relationship of SBP to MM continues to be controversial. Recommendations on the diagnosis and management of SBP in adults, based on a literature search and consensus of expert opinion, were recently published on behalf of the Guidelines Working Group of the United Kingdom Myeloma Forum 1. MRI of the spine is necessary to assess local disease. Radiotherapy with doses of 45–50 Gy is the recommended treatment and gives a high rate of local control (83–96%). Chemotherapy remains controversial in contrast to MM, in which intensive chemotherapy with autologous bone marrow transplantation (ABMT) is widely accepted. At the present time, considering the good prognosis of patients with a normal MRI at diagnosis and a complete disappearance of the M protein after radiotherapy, we believe that ABMT should be reserved for relapse or primary therapeutic failure. Pediatr Blood Cancer 2006;47:335–338. © 2005 Wiley‐Liss, Inc.
How low is too low? Use of cluster analysis to define low levels of mercaptopurine metabolites
Authors: Traore Fatoumata , O'Riordan Mary Ann , Myers Carolyn , Groth Karen , Hoff Ahna , Angiolillo Anne , Rheingold Susan , Drotar Dennis , Kodish Eric
Published: August 2005

Background

To group patients receiving treatment for acute lymphoblastic leukemia (ALL) according to their oral mercaptopurine (6‐MP) metabolite levels and to establish cut‐off points to screen for potential poor clinical outcome.

Procedure

Methodological study using 6‐MP metabolite levels from 48 adolescent ALL patients enrolled in a multicenter adherence study. Cluster analysis was the primary analytical technique. We used two validation methods (a split‐sampling and a simulation technique) for validating the results.

Results

Four clusters were retained in our initial analysis using our first group of patients (n = 27). Three clusters (labeled 1, 2, and 4) exhibited the expected negative correlation between the two metabolites, that is, “high” values of one were associated with “low” values of the other. One cluster (labeled 3) had “low” levels for both TGN and MMP. Five of the 27 adolescents had their 6‐MP “held” during the study. Post‐hoc examination of the results revealed that all five grouped in Cluster 3 during the time that their medications were stopped, but grouped in other clusters at other times. The median ANC was highest in Cluster 3, consistent with low therapeutic drug levels. Parameters were reproducible with both validation methods. Values below the respective 75th centile for both TGN and MMP in Cluster 3 for the complete sample (n = 48) are suggested as representing a potentially higher risk for relapse.

Conclusions

This study provides an objective method for identifying patients at risk for treatment failure due to suboptimal 6‐MP therapy; the clinical significance of this approach should be examined in future studies. © 2005 Wiley‐Liss, Inc.