bluuebunny/crossref_metadata_2025 huggingface dataset:
Renin–angiotensin vaccine: old story, new project ‘efficacy versus safety’
Authors: MICHEL Jean-Baptiste
Published: July 2004

In the present issue of Clinical Science, Brown and co-workers report preliminary results of Ang I (angiotensin I) immunization in humans. They demonstrate the presence of antibodies in human plasma and report that the procedure is well tolerated, but the blood pressure does not fall. The first attempts to actively immunize against components of the renin–angiotensin system were performed by Goldblatt in the 1950s. In our experience, active immunization against renin was associated with a complete inhibition of endogeneous plasma renin activity and a decrease in blood pressure, followed by the progressive development of a juxtaglomerular autoimmune nephritis. In contrast neither blood pressure nor aldosterone secretion were significantly modified by Ang I immunization. Moreover, Ang I-immunized animals continued to respond to the pharmacological inhibition of renin–angiotensin system. These data provide evidence of the inability of antibodies to target Ang I within tissues.
Simple induction probe electric field meter for the detection of electrical fields generated by ion-optical electrodes
Authors: Appel Matthew F. , McKeachie J Ryan , van der Veer Wytze E. , Benter Thorsten
Published: July 2004

A simple electric field probe was developed and used to assess the electrical fields produced inside an ion-optical system. When attached to an XYZ translation stage, this induction probe electrometer is capable of spatially mapping the electrical fields generated by a variety of ion-optical arrangements. Measurements of the electrical fields produced by a conventional reflectron consisting of discrete electrodes and monolithic volume and surface conductive polymeric reflectrons are compared. The performance of the system is validated and a correction is introduced to compensate for capacitive coupling between the probe and the electrode system investigated.
Solutions for a fractional nonlinear diffusion equation: Spatial time dependent diffusion coefficient and external forces
Authors: Lenzi E. K. , Mendes R. S. , Sau Fa Kwok , da Silva L. R. , Lucena L. S.
Published: July 2004

We analyze a generalized diffusion equation which extends some known equations such as the fractional diffusion equation and the porous medium equation. We start our investigation by considering the linear case and the nonlinear case afterward. The linear case is discussed taking fractional time and spatial derivatives into account in a unified approach. We also discuss the modifications that emerge by employing simple drifts and the diffusion coefficient given by D(x,t)=D(t)|x|−θ. For the nonlinear case, we study scaling behavior of the time in connection with the asymptotic behavior for the solution of the nonlinear fractional diffusion equation.
Ferroelectric and electrical behavior of (Na0.5Bi0.5)TiO3 thin films
Authors: Zhou Z. H. , Xue J. M. , Li W. Z. , Wang J. , Zhu H. , Miao J. M.
Published: July 2004

Sodium bismuth titanate (Na0.5Bi0.5)TiO3 (NBT) of perovskite structure is among the best known lead-free piezoelectric∕ferroelectric that promises a number of applications in sensors and actuators. However, NBT in thin film form has not been properly investigated, although NBT in bulk ceramic form has been widely studied. In this letter, we report the growth of polycrystalline NBT thin films by radio-frequency magnetron sputtering and their ferroelectric behavior. The NBT thin films exhibit a well-defined hysteresis loop, with a remanent polarization of 11.9μC∕cm2 and coercive field of 37.9kV∕cm when measured at room temperature. There is a steady decrease of dielectric constant in the range of 650–470 over the frequency range of 10–105Hz. A change in the controlling mechanism of electrical behavior from the grain interior to the grain boundary is observed for the NBT thin film with increasing temperature. Hopping of oxygen vacancies trapped at the grain boundaries is responsible for the high dielectric loss at low frequencies and high dc conductivity observed.
Instabilities in the flow of thin films on heterogeneous surfaces
Authors: Kondic Lou , Diez Javier
Published: July 2004

We present computational and experimental results involving instability development in the gravity-driven flow of thin fluid films on heterogeneous surfaces, with particular emphasis on the dynamics of the fluid fronts. We show that heterogeneity of the solid surface can have a significant effect on the flow dynamics. Since the effect of heterogeneity often competes with the basic instability mechanism that would occur even on macroscopically homogeneous surfaces, the result is an elaborate interplay of various instability mechanisms. The computational results presented here outline both the flow on surfaces perturbed by regular patterns, and on surfaces perturbed by irregular, noiselike perturbations. We relate these computational results to the pattern formation process in our experiments of gravity-driven flow down an incline. Good qualitative agreement is found between the simulations and the experiments.
A phonon depletion effect in ultrathin heterostructures with acoustically mismatched layers
Authors: Pokatilov Evgenii P. , Nika Denis L. , Balandin Alexander A.
Published: July 2004

We demonstrate theoretically that modification of the acoustic phonon spectrum in semiconductor heterostructures with large acoustic impedance mismatch between the core and cladding layers may lead to strong phonon depletion in the core layer. The latter is achieved if the heterostructure parameters are properly tuned, i.e., the structure thickness is in nanometer scale to ensure phonon quantization and the cladding layers are acoustically “softer” than the core layer. Using a numerical solution of the elasticity equation, we show that one can achieve conditions when almost all acoustic phonon modes are squeezed in the cladding layers with the exception of a small fraction of phonons with very small wave vectors (q⩽0.3nm−1). The predicted phonon depletion effect in the core layer of the acoustically mismatched heterostructures may lead to increased carrier mobility in certain regions of the heterostructure as well as improved thermal management of heterostructure-based devices.
Dielectric relaxor behavior of Cd2Nb2O7
Authors: Yu Zhi , Ang Chen
Published: July 2004

The dc electric-field dependence of the dielectric properties of cadmium niobate Cd2Nb2O7 single crystals is studied, and characteristics of the dielectric behavior of Cd2Nb2O7 under dc bias are revealed. The temperature (Tm) where the dielectric relaxation mode occurs is independent of dc bias levels, while its intensity is greatly suppressed and finally eliminated with increasing dc bias from 0 to 15kV∕cm. The observed dielectric relaxation features of Cd2Nb2O7 can be attributed to “dielectric relaxor” behavior, rather than “ferroelectric relaxor” behavior previously designated in literature. The physical nature of the dielectric relaxor behavior is briefly discussed.
Sphalerite–rock salt phase transition in ZnMnSe heterostructures
Authors: Litvinov D. , Gerthsen D. , Rosenauer A. , Daniel B. , Hetterich M.
Published: July 2004

We report on the investigation of epitaxial MnSe layers grown on ZnSe by transmission electron microscopy. MnSe∕ZnSe superlattices (SLs) with different nominal MnSe thicknesses tMnSe between 2 and 20 monolayers (MLs) were investigated, which were grown by molecular-beam epitaxy on GaAs(001) substrates. Composition profiles of the SLs were evaluated by the measurement of local (002) lattice parameters in growth direction. A MnSe deposition between 2 and 4MLs on ZnSe leads to the formation of intermixed Zn1−xMnxSe layers with sphalerite structure and a Mn concentration x increasing from 50% to 90%. For MnSe layers with a thickness between 6 and 20ML, we observe 5–10nm small MnSe inclusions with a rock salt structure embedded in sphalerite Zn1−xMnxSe with approximately 90%Mn.
Determining the equation-of-state isentrope in an isochoric heated plasma
Authors: Foord M. E. , Reisman D. B. , Springer P. T.
Published: July 2004

A novel method for determining the equation-of-state (EOS) along the release isentrope in an isochoric (constant volume) heated plasma is presented. This approach is demonstrated using simulations of a solid density, 10 eV expanding Al plasma. Determining the material EOS data is validated to pressures near 80 Mbar, much higher than current isentropic compression experiments allow. Limitations at very high temperature (Te⩾100 eV), due to the formation of a radiative conduction layer near the rarefaction interface, are also discussed.
Direct use of the mass output of a thermobalance for controlling the reaction rate of solid-state reactions
Authors: Diánez M. J. , Pérez Maqueda L. A. , Criado J. M.
Published: July 2004

Sample controlled thermal analysis equipment has been developed constituted by an electrobalance in which the mass output (TG signal) is directly used for monitoring the temperature of thermal decomposition reactions under constant rate thermal analysis (CRTA) or stepwise isothermal analysis (SIA) control. The sample weight is programmed to follow a preset linear decrease as a function of the time by means of a conventional controller, that at the time control a second conventional temperature programmer. The CRTA control is achieved by controlling the temperature is such a way that if the mass input is higher than the setpoint, the temperature increases at a predefined heating rate; while if the mass input is lower than the setpoint, the temperature decreases at a predefined cooling rate. The SIA control is achieved by selecting the run–hold command from the menu of the digital input of the temperature programmer. In such a case, the programmed linear heating schedule is in progress while the sample weight is higher than the setpoint and an isothermal dwell is maintained as soon as the weight becomes lower than the setpoint. The direct use of the mass output for the control provides a higher sensitivity for selecting very low values of constant reaction rates than the more conventional methods using the DTG output as control parameter. The thermal degradation of polyvinye chloride (PVC) has been used for checking the behavior of the equipment here developed, showing that the dehydrochlorination of PVC is controlled either by a nucleation and growth of nuclei or by a random scission of the main chain of the polymer.
Quantitative analysis of nanoscale switching in SrBi2Ta2O9 thin filmsby piezoresponse force microscopy
Authors: Kalinin Sergei V. , Gruverman Alexei , Bonnell Dawn A.
Published: July 2004

Local switching properties in SrBi2Ta2O9 thin films have been studied by spatially resolved piezoresponse force microscopy (PFM) and spectroscopy. Variations in PFM contrast of individual grains due to their random crystallographic orientation are consistent with the grain switching behavior examined via vertical and lateral hysteresis loops. Theoretical description of vertical hysteresis loop shape obtained in the point-charge approximation is shown to be in good agreement with the experimental data. Dependence of the hysteresis loop parameters on the grain crystallographic orientation is analyzed. It has been found that grain deviation from the ideal (010) orientation when the polar axis is normal to the film plane results in the decrease of the PFM signal and increase of the coercive voltage in agreement with theoretical predictions.
Investigation on the magnetic and electrical properties of crystalline Mn0.05Si0.95 films
Authors: Zhang F. M. , Liu X. C. , Gao J. , Wu X. S. , Du Y. W. , Zhu H. , Xiao J. Q. , Chen P.
Published: July 2004

The magnetic and electrical properties of crystalline Mn0.05Si0.95 films prepared by post-thermal treatment of the as-deposited amorphous Si-Mn (95at.%−5at.%) have been investigated. Both the temperature dependence and field dependence of magnetization were measured using superconducting quantum interference devices, and it has been indicated that the film materials are ferromagnetic with Curie temperature over 400K. X-ray diffraction analysis revealed full crystallization of the films and the incorporation of Mn into the host crystalline Si lattice. Behavior of thermally activated conduction processes of the films has been evinced by electrical property measurement for the films.
Change of the electrical properties in Fe-Al2O3 granular films
Authors: Boff M. A. S. , Teixeira S. R. , Schmidt J. E. , Antunes A. B.
Published: July 2004

A systematic study of the electrical resistance as a function of the temperature was performed in Fe-Al2O3 granular thin films. Our findings revealed a nonlinear dependence of the current versus voltage in the low field regime at low temperature. The variable range hopping mechanism is the best description of the behavior of our samples. A change of the electronic properties can be observed depending on the direct current applied to the sample’s plane, and is related to different localization lengths.
Determination of cations distribution in Mn3O4 by anomalous x-ray powder diffraction
Authors: Xiao Yanan , Wittmer Dale E. , Izumi Fujio , Mini Susan , Graber Tim , Viccaro P. James
Published: July 2004

The oxidation states of Mn at two different crystallographic sites in the distorted spinel structure of Mn3O4 were determined by the approach of anomalous synchrotron x-ray powder diffraction. The real parts of anomalous scattering factors for the two Mn sites were refined from a series of powder diffraction patterns collected at the vicinity of K absorption edge of Mn. The results of Rietveld refinements showed that the two distinct cation sites can obviously be distinguished from each other and that Mn2+ ions occupy the tetrahedral site and Mn3+ ions are located at the octahedral site.
35
GHz
mode-locking of 1.3μm quantum dot lasers
Authors: Kuntz M. , Fiol G. , Lämmlin M. , Bimberg D. , Thompson M. G. , Tan K. T. , Marinelli C. , Penty R. V. , White I. H. , Ustinov V. M. , Zhukov A. E. , Shernyakov Yu. M. , Kovsh A. R.
Published: July 2004

35 GHz passive mode-locking of 1.3μm (InGa)As∕GaAs quantum dot lasers is reported. Hybrid mode-locking was achieved at frequencies up to 20GHz. The minimum pulse width of the Fourier-limited pulses was 7ps with a peak power of 6mW. Low uncorrelated timing jitter below 1ps was found in cross correlation experiments. High-frequency operation of the lasers was eased by a ridge waveguide design that includes etching through the active layer.
Removal of thick (>100nm) InGaN layers for optical devices using band-gap-selective photoelectrochemical etching
Authors: Haberer E. D. , Sharma R. , Stonas A. R. , Nakamura S. , DenBaars S. P. , Hu E. L.
Published: July 2004

We report on band-gap-selective photoelectrochemical (PEC) etching of thick InGaN layers for use in optical devices, such as GaN microdisks, distributed Bragg reflectors, and two-dimensional photonic crystal membranes. Three InGaN sacrificial layer structures are studied: a 300nm InGaN layer, an InGaN∕GaN superlattice, and an InGaN∕InGaN superlattice. Calculated equilibrium band diagrams of the epitaxial structures are used to explain the observed etching behavior. The strong piezoelectric-induced fields within the InGaN sacrificial layers are found to greatly affect carrier confinement and etching behavior. As a demonstration of the etching technique, a free-standing GaN microdisk on an InGaN post is fabricated.
Low-frequency noise in AlSb∕InAs high-electron-mobility transistor structure as a function of temperature and illumination
Authors: Kruppa W. , Yang M. J. , Bennett B. R. , Boos J. B.
Published: July 2004

Measurements of the low-frequency noise in AlSb∕InAs high-electron-mobility transistor structures over the temperature range between 60 and 300K are reported. Without illumination, the slope of the noise level with frequency was found to be close to 1∕f with a Hooge parameter, αH, of 9×10−3 at room temperature. With broad-spectrum visible-light illumination at lower temperatures, however, the noise level increases greatly and displays a strong Lorentzian component with the characteristic 1∕f2 slope above the corner frequency. The associated sheet resistance also increases greatly, consistent with previously observed negative photoconductivity in AlSb∕InAs quantum wells.
Structure formation upon reactive direct current magnetron sputteringof transition metal oxide films
Authors: Ngaruiya J. M. , Kappertz O. , Mohamed S. H. , Wuttig M.
Published: July 2004

A comparative study of reactive direct current magnetron sputtering for different transition metal oxides reveals crystalline films at room temperature for group 4 and amorphous films for groups 5 and 6. This observation cannot be explained by the known growth laws and is attributed to the impact of energetic particles, originating from the oxidized target, on the growing film. This scenario is supported by measured target characteristics, the evolution of deposition stress of the films, and the observed backsputtering.
A molecular dynamics study of round and flattened carbon nanotube structures
Authors: Liu Henry J. , Cho Kyeongjae
Published: July 2004

Large diameter single wall carbon nanotubes exist with both round right cylinder and barbell-like flattened cross sections. Using an adaptive intermolecular reactive bond order potential, we examine the characteristics of both configurations by using molecular dynamics simulations. We then continue to examine the dynamical transition from the flattened to round state by charge injection. Predictions based on these simulations provide a basis for the design of active fluid transport devices, and nanoscale mechanical systems/motors.
Acoustic phonon mode splitting behavior of an asymmetric y-branch three terminal junction
Authors: Li Wen-Xia , Chen Ke-Qiu , Duan Wenhui , Wu Jian , Gu Bing-Lin
Published: July 2004

The acoustic phonon transport through an asymmetric y-branch semiconductor quantum structure is investigated by use of the scattering-matrix method. It is found that the quantum structure exhibits mode-splitting behavior, resonant transmission, and the noninteger quantized thermal conductance at very low temperatures. The thermal transport behavior sensitively depends on the geometric configuration of the structure. Our work suggests that such a y-branch structure with specific structural parameters could be used as a splitter of phonon modes.
Effect of water stress on partitioning of 14C-labelled photosynthates in Vitis vinifera
Authors: Bota Josefina , Stasyk Oleg , Flexas Jaume , Medrano Hipólito
Published: July 2004

The influence of fruits on export and distribution of photosynthates was studied in Vitis vinifera L. cv. Tempranillo using 14C labelling. Also, the influence of water stress was analysed in fruiting and fruitless plants of Tempranillo and fruiting plants of cv. Alfonso Lavallée. In fruitless plants of Tempranillo, reserve organs (trunk, roots and lower shoot) represented 80% of total plant dry matter (DM), and imported up to 90% of the total 14C exported from the fed leaf. Therefore, the distribution pattern of photosynthates in these plants reflected mainly the sink size. However, the presence of fruits in Tempranillo strongly stimulated 14C export and changed the distribution pattern of assimilates. Fruits imported up to 70–80% of the total 14C exported, while representing only 25% of the total plant DM. Therefore, the strength of fruits as carbon sinks was independent of sink size, and it is discussed on the basis of a water potential gradient theory. Water stress caused a significant reduction of leaf water potential, photosynthesis and stomatal conductance, but caused only a slight, non-significant, decrease of carbohydrate export from the fed leaves, and did not affect the distribution pattern of 14C except in some minor fractions in Tempranillo. The 14C distribution into different fruit components was also unaffected. In contrast, in Alfonso Lavallée water stress resulted in a highly significant reduction of export, and an altered photosynthate distribution pattern. These differences could be due to the lower water potential attained in stressed Alfonso Lavallée plants.
Sphingosine 1-phosphate activates Weibel-Palade body exocytosis
Authors: Matsushita Kenji , Morrell Craig N. , Lowenstein Charles J.
Published: July 2004

Sphingosine 1-phosphate (S1P) not only regulates angiogenesis, vascular permeability and vascular tone, but it also promotes vascular inflammation. However, the molecular basis for the proinflammatory effects of S1P is not understood. We now show that S1P activates endothelial cell exocytosis of Weibel-Palade bodies, releasing vasoactive substances capable of causing vascular thrombosis and inflammation. S1P triggers endothelial exocytosis in part through phospholipase C-γ signal transduction. However, S1P also modulates endothelial cell exocytosis by activating endothelial nitric oxide synthase production of nitric oxide, which inhibits exocytosis. Thus S1P plays a dual role in regulating endothelial exocytosis, triggering pathways that both promote and inhibit endothelial exocytosis. Regulation of endothelial exocytosis may explain part of the proinflammatory effects of S1P.
Mapping of sudden infant death with dysgenesis of the testes syndrome (SIDDT) by a SNP genome scan and identification of
TSPYL
loss of function
Authors: Puffenberger Erik G. , Hu-Lince Diane , Parod Jennifer M. , Craig David W. , Dobrin Seth E. , Conway Andrew R. , Donarum Elizabeth A. , Strauss Kevin A. , Dunckley Travis , Cardenas Javier F. , Melmed Kara R. , Wright Courtney A. , Liang Winnie , Stafford Phillip , Flynn C. Robert , Morton D. Holmes , Stephan Dietrich A.
Published: July 2004

We have identified a lethal phenotype characterized by sudden infant death (from cardiac and respiratory arrest) with dysgenesis of the testes in males [Online Mendelian Inheritance in Man (OMIM) accession no. 608800]. Twenty-one affected individuals with this autosomal recessive syndrome were ascertained in nine separate sibships among the Old Order Amish. High-density single-nucleotide polymorphism (SNP) genotyping arrays containing 11,555 single-nucleotide polymorphisms evenly distributed across the human genome were used to map the disease locus. A genome-wide autozygosity scan localized the disease gene to a 3.6-Mb interval on chromosome 6q22.1-q22.31. This interval contained 27 genes, including two testis-specific Y-like genes (
TSPYL
and
TSPYL4
) of unknown function. Sequence analysis of the
TSPYL
gene in affected individuals identified a homozygous frameshift mutation (457_458insG) at codon 153, resulting in truncation of translation at codon 169. Truncation leads to loss of a peptide domain with strong homology to the nucleosome assembly protein family. GFP-fusion expression constructs were constructed and illustrated loss of nuclear localization of truncated TSPYL, suggesting loss of a nuclear localization patch in addition to loss of the nucleosome assembly domain. These results shed light on the pathogenesis of a disorder of sexual differentiation and brainstem-mediated sudden death, as well as give insight into a mechanism of transcriptional regulation.
Nuclear scaffold/matrix attached region modules linked to a transcription unit are sufficient for replication and maintenance of a mammalian episome
Authors: Jenke Andreas C. W. , Stehle Isa M. , Herrmann Frank , Eisenberger Tobias , Baiker Armin , Bode Jürgen , Fackelmayer Frank O. , Lipps Hans J.
Published: July 2004

The activation of mammalian origins of replication depends so far on ill understood epigenetic events, such as binding of transcription factors, chromatin structure, and nuclear localization. Understanding these mechanisms is not only a scientific challenge but also represents a prerequisite for the rational design of nonviral episomal vectors for mammalian cells. In this paper, we demonstrate that a tetramer of a 155-bp minimal nuclear scaffold/matrix attached region DNA module linked to an upstream transcription unit is sufficient for replication and mitotic stability of a mammalian episome in the absence of selection. Fluorescence
in situ
hybridization analyses, crosslinking with
cis
-diammineplatinum(II)-dichloride and chromatin immunoprecipitation demonstrate that this vector associates with the nuclear matrix or scaffold
in vivo
by means of specific interaction of the nuclear scaffold/matrix attached region with the nuclear matrix protein SAF-A. Results presented in this paper define the minimal requirements of an episomal vector for mammalian cells on the molecular level.
The total synthesis of (–)-crispatene
Authors: Miller Aubry K. , Byun Daniel H. , Beaudry Christopher M. , Trauner Dirk
Published: July 2004

The total synthesis of the molluscan polypropionate (–)-crispatene is described. The synthesis features a palladium-catalyzed cross-coupling to establish a sensitive conjugated tetraene and its Lewis acid-catalyzed cycloisomerization to yield the bicyclo[3.1.0]hexene core of the natural product. The absolute configuration of (–)-crispatene and related molecules is established.
Mechanical switching and coupling between two dissociation pathways in a P-selectin adhesion bond
Authors: Evans Evan , Leung Andrew , Heinrich Volkmar , Zhu Cheng
Published: July 2004

Many biomolecular bonds exhibit a mechanical strength that increases in proportion to the logarithm of the rate of force application. Consistent with exponential decrease in bond lifetime under rising force, this kinetically limited failure reflects dissociation along a single thermodynamic pathway impeded by a sharp free energy barrier. Using a sensitive force probe to test the leukocyte adhesion bond P-selectin glycoprotein ligand 1 (PSGL-1)–P-selectin, we observed a linear increase of bond strength with each 10-fold increase in the rate of force application from 300 to 30,000 pN/sec, implying a single pathway for failure. However, the strength and lifetime of PSGL-1–P-selectin bonds dropped anomalously when loaded below 300 pN/sec, demonstrating unexpectedly faster dissociation and a possible second pathway for failure. Remarkably, if first loaded by a “jump” in force to 20–30 pN, the bonds became strong when subjected to a force ramp as slow as 30 pN/sec and exhibited the same single-pathway kinetics under all force rates. Applied in this way, a new “jump/ramp” mode of force spectroscopy was used to show that the PSGL-1–P-selectin bond behaves as a mechanochemical switch where force history selects between two dissociation pathways with markedly different properties. Furthermore, replacing PSGL-1 by variants of its 19-aa N terminus and by the crucial tetrasaccharide sialyl Lewis
X
produces dramatic changes in the failure kinetics, suggesting a structural basis for the two pathways. The two-pathway switch seems to provide a mechanism for the “catch bond” response observed recently with PSGL-1–P-selectin bonds subjected to small-constant forces.
Molecular-timetable methods for detection of body time and rhythm disorders from single-time-point genome-wide expression profiles
Authors: Ueda Hiroki R. , Chen Wenbin , Minami Yoichi , Honma Sato , Honma Kenichi , Iino Masamitsu , Hashimoto Seiichi
Published: July 2004

Detection of individual body time (BT) via a single-time-point assay has been a longstanding unfulfilled dream in medicine, because BT information can be exploited to maximize potency and minimize toxicity during drug administration and thus will enable highly optimized medication. To achieve this dream, we created a “molecular timetable” composed of >100 “time-indicating genes,” whose gene expression levels can represent internal BT. Here we describe a robust method called the “molecular-timetable method” for BT detection from a single-time-point expression profile. The power of this method is demonstrated by the sensitive and accurate detection of BT and the sensitive diagnosis of rhythm disorders. These results demonstrate the feasibility of BT detection based on single-time-point sampling, suggest the potential for expression-based diagnosis of rhythm disorders, and may translate functional genomics into chronotherapy and personalized medicine.
Simultaneous absence of dopamine D1 and D2 receptor-mediated signaling is lethal in mice
Authors: Kobayashi Minoru , Iaccarino Ciro , Saiardi Adolfo , Heidt Valérie , Bozzi Yuri , Picetti Roberto , Vitale Carmine , Westphal Heiner , Drago John , Borrelli Emiliana
Published: July 2004

Dopamine (DA) controls a wide variety of physiological functions in the central nervous system as well as in the neuroendocrine and gastrointestinal systems. DA signaling is mediated by five cloned receptors named D1-D5. Knockout mouse models for the five receptors have been generated, and, albeit impaired for some important DA-mediated functions, they are viable and can reproduce. D1 and D2 receptors are the most abundant and widely expressed DA receptors. Cooperative/synergistic effects mediated by these receptors have been suggested, in particular, in the control of motor behaviors. To analyze the extent of such interrelationship, we have generated double D1/D2 receptor mutants. Interestingly, in contrast to single knockouts, we found that concurrent ablation of the D1 and D2 receptors is lethal during the second or third week after birth. This dramatic phenotype is likely to be related to altered feeding behavior and dysfunction of the gastrointestinal system, especially because major anatomical changes were not identified in the brain. Similarly, in the absence of functional D1, heterozygous D2 mutants (
D1r
-/-
;
D2r
+/-
) showed severe growth retardation and did not survive their postweaning period. The analysis of motor behavior in
D1r
/
D2r
compound mutants showed that loss of D2-mediated functions reduces motor abilities, whereas the effect of
D1r
ablation on locomotion strongly depends on the experimental paradigms used. These studies highlight the interrelationship between D1 and D2 receptor-mediated control of motor activity, food intake, and gastrointestinal functions, which has been elusive in the single-gene ablation studies.
CSTX-13, a highly synergistically acting two-chain neurotoxic enhancer in the venom of the spiderCupiennius salei(Ctenidae)
Authors: Wullschleger Benno , Kuhn-Nentwig Lucia , Tromp Jan , Kämpfer Urs , Schaller Johann , Schürch Stefan , Nentwig Wolfgang
Published: July 2004

The survival of the spiderCupiennius saleidepends on its hunting success, which largely relies on its immediately paralyzing multicomponent venom. Here, we report on the isolation and characterization of CSTX-13, a neurotoxic enhancer in the spider venom.De novoelucidation of the disulfide bridge pattern of CSTX-13 and the neurotoxin CSTX-1 by tandem MS revealed an identical arrangement. However, in contrast to CSTX-1, CSTX-13 is a two-chain peptide with two interchain and two intrachain disulfide bridges. Furthermore, the insecticidal activity of CSTX-13 is synergistically increased in the presence of K+ions as well as of the cytolytic peptide cupiennin 1a. We demonstrated that the weakly neurotoxic CSTX-13 enhances the paralytic activity of the neurotoxin CSTX-1 by 65% when it is administered with the latter at its entirely nontoxic physiological concentration, which is 440 times below its LD50concentration.
Studies of stereocontrolled allylation reactions for the total synthesis of phorboxazole A
Authors: Williams David R. , Kiryanov Andre A. , Emde Ulrich , Clark Michael P. , Berliner Martin A. , Reeves Jonathan T.
Published: July 2004

A highly convergent total synthesis of the potent anticancer agent (+)-phorboxazole A (
1
) is accomplished. Four components (
3
–
6
) are assembled with considerations for control of absolute and relative stereochemistry. Iterative asymmetric allylation methodology addresses key stereochemical features in the preparation of the 2,6-
cis
- and 2,6-
trans
-tetrahydropyranyl rings of the C3–C19 component (
3
). The stereocontrolled asymmetric allylation process is also used for development of the C28–C41 fragment (
4
). Novel Barbier coupling reactions of α-iodomethyl oxazoles and related thiazoles are described with samarium iodide. The convergent assembly of components 4 and 5 features formation of the fully substituted C22–C26 pyran by intramolecular capture of an allyl cation intermediate with high facial selectivity, and further efforts lead to
E
-C19/C20 olefination. The synthesis culminates with use of a modified Julia olefination for attachment of the C42–C46 segment and subsequent late-stage macrocyclization by installation of the (
Z
)-C2/C3 α,β-unsaturated lactone.
Red cell membrane and plasma linoleic acid nitration products: Synthesis, clinical identification, and quantitation
Authors: Baker Paul R. S. , Schopfer Francisco J. , Sweeney Scott , Freeman Bruce A.
Published: July 2004

Nitric oxide (

NO) and its reactive metabolites mediate the oxidation, nitration, and nitrosation of DNA bases, amino acids, and lipids. Here, we report the structural characterization and quantitation of two allylic nitro derivatives of linoleic acid (LNO
2
), present as both free and esterified species in human red cell membranes and plasma lipids. The LNO
2
isomers 10-nitro-9-
cis
, 12-
cis
-octadecadienoic acid and 12-nitro-9-
cis
, 12-
cis
-octadecadienoic acid were synthesized and compared with red cell and plasma LNO
2
species based on chromatographic elution and mass spectral properties. Collision-induced dissociation fragmentation patterns from synthetic LNO
2
isomers were identical to those of the two most prevalent LNO
2
positional isomers found in red cells and plasma. By using [
13
C]LNO
2
as an internal standard, red cell free and esterified LNO
2
content was 50 ± 17 and 249 ± 104 nM, respectively. The free and esterified LNO
2
content of plasma was 79 ± 35 and 550 ± 275 nM, respectively. Nitrated fatty acids, thus, represent the single largest pool of bioactive oxides of nitrogen in the vasculature, with a net LNO
2
concentration of 477 ± 128 nM, excluding buffy coat cells. These observations affirm that basal oxidative and nitrating conditions occur in healthy humans to an extent that is sufficient to induce abundant membrane and lipoprotein–fatty acid nitration. Given that LNO
2
is capable of mediating cGMP and non-cGMP-dependent signaling reactions, fatty acid nitration products are species representing the convergence of

NO and oxygenated lipid cell-signaling pathways.
Discriminatory aptamer reveals serum response element transcription regulated by cytohesin-2
Authors: Theis Mirko G. , Knorre Alexander , Kellersch Bettina , Moelleken Jörg , Wieland Felix , Kolanus Waldemar , Famulok Michael
Published: July 2004

Cytohesins are a family of highly homologous guanine nucleotide exchange factors (GEFs) that act on ADP-ribosylation factors (ARFs). The small ARF-GEFs are involved in integrin signaling, actin cytoskeleton remodeling, and vesicle transport. Here, we selected and applied a specific inhibitor for ARF nucleotide-binding site opener (ARNO)/cytohesin-2, an RNA aptamer that clearly discriminates between cytohesin-1 and cytohesin-2. This reagent bound to an N-terminal segment of cytohesin-2 and did not inhibit ARF-GEF function
in vitro
. When transfected into HeLa cells, it persisted for at least 6 h without requiring stabilization. Its effect
in vivo
was to down-regulate gene expression mediated through the serum-response element and knockdown mitogen-activated protein kinase activation, indicating that cytohesin-2 acts by means of mitogen-activated protein kinase signaling. We conclude that the N-terminal coiled-coil and parts of the Sec7 domain of cytohesin-2 are required for serum-mediated transcriptional activation in nonimmune cells, whereas cytohesin-1 is not. Our results indicate that intramer technology can be used not only for assigning novel biological functions to proteins or protein domains but also to prove nonredundancy of highly homologous proteins.
Chromatin landscape dynamics of theIl4–Il13locus during T helper 1 and 2 development
Authors: Baguet Aurélie , Bix Mark
Published: July 2004

Il4andIl13encode the canonical T helper 2 (TH2) cytokines responsible both for promoting immune responses against extracellular pathogens and, when misregulated, causing allergic and autoimmune disease. The expression potential of these genes undergoes developmentally programmed repression and enhancement during commitment of naïve CD4+T cells to the mature T helper 1 (TH1) and TH2 fates, respectively. Thus, like the globin locus, the TH2 cytokine locus provides a highly tractable system to study a developmental fate choice leading to alternative transcriptional states of either silence or permissivity. We used quantitative chromatin immunoprecipitation and RT-PCR to correlate changes in the transcriptional states ofIl4andIl13with markers of permissive chromatin across theIl4–Il13locus in naïve CD4+T cells undergoing TH1 and TH2 differentiation. We provide evidence that DNaseI hypersensitive site V in theIl43′ enhancer is the likely target for signals maintainingIl4andIl13transcriptional permissivity in naïve cells. We also demonstrate rapid acquisition of differences in H3 acetylation between TH1- and TH2-primed cells, indicating a developmentally early role for cytokine signaling in the process of THcell fate determination. Finally, we show that transcriptional repression correlates with the disappearance of permissive H3 modifications from everywhere in theIl4–Il13locus except hypersensitive site IV, suggesting a critical role for this element in the maintenance of transcriptional repression. Our findings are consistent with a progressive regulatory element activation/deactivation model of TH1/TH2 development.
5′ Long serial analysis of gene expression (LongSAGE) and 3′ LongSAGE for transcriptome characterization and genome annotation
Authors: Wei Chia-Lin , Ng Patrick , Chiu Kuo Ping , Wong Chee Hong , Ang Chin Chin , Lipovich Leonard , Liu Edison T. , Ruan Yijun
Published: July 2004

Complete genome annotation relies on precise identification of transcription units bounded by a transcription initiation site (TIS) and a polyadenylation site (PAS). To facilitate this process, we developed a set of two complementary methods, 5′ Long serial analysis of gene expression (LS) and 3′LS. These analyses are based on the original SAGE and LS methods coupled with full-length cDNA cloning, and enable the high-throughput extraction of the first and the last 20 bp of each transcript. We demonstrate that the mapping of 5′LS and 3′LS tags to the genome allows the localization of TIS and PAS. By using 537 tag pairs mapping to the region of known genes, we confirmed that >90% of the tag pairs appropriately assigned to the first and last exons. Moreover, by using tag sequences as primers for RT-PCRs, we were able to recover putative full-length transcripts in 81% of the attempts. This large-scale generation of transcript terminal tags is at least 20–40 times more efficient than full-length cDNA cloning and sequencing in the identification of complete transcription units. The apparent precision and deep coverage makes 5′LS and 3′LS an advanced approach for genome annotation through whole-transcriptome characterization.
Herpes simplex virus type-1 induces IFN-α production via Toll-like receptor 9-dependent and -independent pathways
Authors: Hochrein Hubertus , Schlatter Beatrix , O'Keeffe Meredith , Wagner Cornelia , Schmitz Frank , Schiemann Matthias , Bauer Stefan , Suter Mark , Wagner Hermann
Published: July 2004

Type I IFN production in response to the DNA virus herpes simplex virus type-1 (HSV-1) is essential in controlling viral replication. We investigated whether plasmacytoid dendritic cells (pDC) were the major tissue source of IFN-α, and whether the production of IFN-α in response to HSV-1 depended on Toll-like receptor 9 (TLR9). Total spleen cells or bone marrow (BM) cells, or fractions thereof, including highly purified pDC, from WT, TLR9, and MyD88 knockout mice were stimulated with known ligands for TLR9 or active HSV-1. pDC freshly isolated from both spleen and BM were the major source of IFN-α in response to oligodeoxynucleotides containing CpG motifs, but in response to HSV-1 the majority of IFN-α was produced by other cell types. Moreover, IFN-α production by non-pDC was independent of TLR9. The tissue source determined whether pDC responded to HSV-1 in a strictly TLR9-dependent fashion. Freshly isolated BM pDC or pDC derived from culture of BM precursors with FMS-like tyrosine kinase-3 ligand, produced IFN-α in the absence of functional TLR9, whereas spleen pDC did not. Heat treatment of HSV-1 abolished maturation and IFN-α production from all TLR9-deficient DC but not WT DC. Thus pDC and non-pDC produce IFN-α in response to HSV-1 via both TLR9-independent and -dependent pathways.
Integrin β3 regions controlling binding of murine mAb 7E3: Implications for the mechanism of integrin αIIbβ3 activation
Authors: Artoni Andrea , Li JiHong , Mitchell Beau , Ruan Jian , Takagi Junichi , Springer Timothy A. , French Deborah L. , Coller Barry S.
Published: July 2004

Abciximab, a derivative of the murine mAb 7E3, protects against ischemic complications of percutaneous coronary interventions by inhibiting ligand binding to the αIIbβ3 receptor. In this study we identified regions on integrin β3 that control 7E3 binding. Murine/human amino acid substitutions were created in two regions of the βA domain that previous studies found to influence 7E3 binding: the C177–C184 loop and K125–N133. The T182N substitution and a K125Q mutation reduced 7E3 binding to human β3 in complex with αIIb. The introduction of both the human C177–C184 region and human W129 into murine β3 was necessary and sufficient to permit 7E3 binding to the human αIIb/murine β3 complex. Although we cannot exclude allosteric effects, we propose that 7E3 binds between C177–C184 and W129, which are within 15 Å of each other in the crystal structure and close to the β3 metal ion-dependent adhesion site. We previously demonstrated that 7E3 binds more rapidly to activated than unactivated platelets. Because it has been proposed that αIIbβ3 changes from a bent to an extended conformation upon activation, we hypothesized that 7E3 binds less well to the bent than the extended conformation. In support of this hypothesis we found that 7E3 bound less well to an αIIbβ3 construct locked in a bent conformation, and unlocking the conformation restored 7E3 binding. Thus, our data are consistent with αIIbβ3 existing in variably bent conformations in equilibrium with each other on unactivated platelets, and activation resulting in αIIbβ3 adopting a more extended conformation.
Mutations in herpes simplex virus glycoprotein D that prevent cell entry via nectins and alter cell tropism
Authors: Manoj Sharmila , Jogger Cheryl R. , Myscofski Dawn , Yoon Miri , Spear Patricia G.
Published: July 2004

Glycoprotein D (gD) determines which cells can be infected by herpes simplex virus (HSV) by binding to one of the several cell surface receptors that can mediate HSV entry or cell fusion. These receptors include the herpesvirus entry mediator (HVEM), nectin-1, nectin-2, and sites in heparan sulfate generated by specific 3-
O
-sulfotransferases. The objective of the present study was to identify residues in gD that are critical for physical and functional interactions with nectin-1 and nectin-2. We found that double or triple amino acid substitutions at positions 215, 222, and 223 in gD caused marked reduction in gD binding to nectin-1 and a corresponding inability to function in cell fusion or entry of HSV via nectin-1 or nectin-2. These substitutions either enhanced or did not significantly inhibit functional interactions with HVEM and modified heparan sulfate. These and other results demonstrate that different domains of gD, with some overlap, are critical for functional interactions with each class of entry receptor. Viral entry assays, using gD mutants described here and previously, revealed that nectins are the principal entry receptors for selected human cell lines of neuronal and epithelial origin, whereas HVEM or nectins could be used to mediate entry into a T lymphocyte line. Because T cells and fibroblasts can be infected via HVEM, HSV strains carrying gD mutations that prevent entry via nectins may establish transient infections in humans, but perhaps not latent infections of neurons, and are therefore candidates for development of safe live virus vaccines and vaccine vectors.
Heterodimerization of type II phytochromes in
Arabidopsis
Authors: Sharrock Robert A. , Clack Ted
Published: July 2004

Coimmunoprecipitation of members of the phytochrome red/farred photoreceptor family from plant extracts has been used to analyze their heteromeric binding interactions. Phytochrome (phy)B or phyD apoproteins with six myc epitopes fused to their N termini are biologically active when expressed in
Arabidopsis
. Immunoprecipitation of either of these tagged proteins from seedling extracts coprecipitates additional type II phytochromes: six myc (myc
6
)-phyB coprecipitates phyC-phyE; and myc
6
-phyD coprecipitates phyB and phyE. No interaction of the epitope-tagged proteins with type I phyA was detected. Gel filtration chromatography shows that all five of the
Arabidopsis
phytochromes are present in seedlings as dimers, and that the heteromeric type II phytochrome complexes migrate at molecular masses characteristic of heterodimers. Similar levels of heterodimer formation are observed in extracts of dark-grown seedlings, where the phytochromes are cytosolic, and light-grown seedlings, where they are predominantly nuclear. These findings indicate that
Arabidopsis
, which until now has been thought to contain five homodimeric forms of phytochrome, in fact contains multiple species of both homodimeric and heterodimeric phytochromes. The conservation of the phytochrome family throughout angiosperms suggests that heterodimeric red/far-red receptors may be present in many flowering plants.
Centromeric DNA sequences in the pathogenic yeast
Candida albicans
are all different and unique
Authors: Sanyal Kaustuv , Baum Mary , Carbon John
Published: July 2004

In an approach to clone and characterize centromeric DNA sequences of
Candida albicans
by chromatin immunoprecipitation, we have used antibodies directed against an evolutionarily conserved histone H3-like protein, CaCse4p (CENP-A homolog). Sequence analysis of clones obtained by this procedure reveals that only eight relatively small regions (≈3 kb each) of the
Can. albicans
genome are selectively enriched. These CaCse4-bound sequences are located within 4- to 18-kb regions lacking ORFs and occur once in each of the eight chromosomes of
Can. albicans
. Binding of another evolutionarily conserved kinetochore protein, CaMif2p (CENP-C homolog), colocalizes with CaCse4p. Deletion of the CaCse4p-binding region of chromosome 7 results in a high rate of loss of the altered chromosome, confirming that CaCse4p, a centromeric histone in the CENP-A family, indeed identifies the functional centromeric DNA of
Can. albicans
. The CaCse4p-rich regions not only lack conserved DNA motifs of point (<400 bp) centromeres and repeated elements of regional (>40 kb) centromeres, but also each chromosome of
Can. albicans
contains a different and unique CaCse4p-rich centromeric DNA sequence, a centromeric property previously unobserved in other organisms.