bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-of-flight emission profiles of the entire plume using fast imaging during pulsed laser deposition of YBa2Cu3O7−x
Authors: Druffner Carl J. , Perram Glen P. , Biggers Rand R.
Published: August 2005

Emission time-of-flight (TOF) profiles have been obtained using gated imagery to further the process control during the pulsed laser deposition of the high temperature superconductor, YBa2Cu3O7−x. An intensified charge coupled device array was used to obtain a sequence of plume images at 10ns temporal resolution and 0.2mm spatial resolution. Plume imagery is transformed to TOF profiles and pulse-to-pulse variations removed using physically based smoothing techniques. Comparison with non-imaging sensors establishes excellent agreement, with systematic uncertainties in streaming speed and temperatures of less than 15% and 8%, respectively. The resulting streaming speeds of 0.4–1.2×106cm∕s and characteristic temperatures of 20000–200000K are characterized across the full plume. This new imaging TOF technique enables the monitoring of the complete evolution of speed distributions. Indeed, significant deviations from the forward-directed Maxwellian speed distributions are observed.
Critical current versus strain measurement up to 21T and 1000A of long length superconducting wires and tapes
Authors: Seeber B. , Uglietti D. , Abächerli V. , Bovier P.-A. , Eckert D. , Kübler G. , Lezza P. , Pollini A. , Flükiger R.
Published: August 2005

A device has been developed to measure the critical current of long length superconductors under uniaxial strain up to 1000A and up to 21T. The latter is based on a modified Walters spring (WASP) where zero applied strain can be precisely controlled. The length of the investigated conductor is on the order of 1m with a typical gauge length between the voltage taps of about 0.5m. This facilitates the measurement of critical currents at an electric field criterion as low as 0.01μV∕cm, which is particularly important for superconductors to be used in magnets which are operated in the persistent mode. The operation of the WASP was simulated by finite element calculations indicating that the radial stress (contact pressure) of the superconductor is less than 5% of the axial stress. The performance of the probe is demonstrated for several Nb3Sn conductors with round and rectangular cross section, respectively, as well as for a Bi-2223 tape.
Low-energy-channeling surface analysis on silicon crystals designed for high-energy-channeling in accelerators
Authors: Baricordi S. , Biryukov V. M. , Carnera A. , Chesnokov Yu. A. , Mea G. Della , Guidi V. , Ivanov Yu. M. , Martinelli G. , Milan E. , Restello S. , Sambo A. , Scandale W. , Vomiero A.
Published: August 2005

Channeling of relativistic particles in bent Si crystals is a powerful technique for use with accelerators. Its efficiency can be found to be highly dependent on the state of the surface of the crystal steering the particles. We investigated the morphology and structure of the surface of the samples that have been used with high efficiency for channeling in accelerators. Low-energy channeling of 2MeVα particles or protons was used as a probe. We found that mechanical treatment of the samples leads to a superficial damaged layer, which is correlated to efficiency limitations of the crystal in accelerators. In contrast, chemical etching, which was used to treat the surface of the most efficient crystals, leaves a surface with superior perfection.
Suns-photoluminescence: Contactless determination of current-voltage characteristics of silicon wafers
Authors: Trupke T. , Bardos R. A. , Abbott M. D. , Cotter J. E.
Published: August 2005

In good silicon solar cells, the separation of the quasi-Fermi energies Δη in the bulk is equivalent to the cell voltage. Photoluminescence is used to measure Δη in both bifacial solar cells and partly processed solar cells. The bifacial cells are used to demonstrate that simultaneous measurement of the photoluminescence signal and of the variable incident light intensity yields pseudo current-voltage characteristics, equivalent to Suns-open circuit voltage (VOC) measurements, but in contactless mode. The applicability of this method to unfinished solar cells, without the need for a solar cell structure, is demonstrated on silicon wafers after various processing steps.
Photon absorption in the Restrahlen band of thin films of GaN and AlN: Two phonon effects
Authors: Yang Jianyong , Brown Gail J. , Dutta Mitra , Stroscio Michael A.
Published: August 2005

Würtzite semiconductors exhibit strong carrier-phonon coupling as well as strong Restrahlen-related absorption of radiation due to the interaction with optical phonons. For the GaN and AlN würtzites studied here, the optical phonon frequencies fall in the infrared region. With the transverse-optical phonon frequency ωt, and longitudinal-optical phonon frequency ωl, when light with frequencies ωt<ω<ωl is incident on a GaN or AlN film, the resonance with optical phonons will lead to strong absorption. In this paper, these effects are modeled and studied experimentally. Our studies show that the absorption is so strong that it is still significant even when the sample thickness is reduced to the submicron level. It is also found experimentally and theoretically that, not only the first harmonic, but also the second harmonic of the phonon frequency leads to strong absorption. Theoretical comparisons with experimental data and predicted transmission versus the energy of the incident light for different film thicknesses are presented.
Interaction of organic surfaces with active species in the high-vacuum environment
Authors: Podzorov V. , Menard E. , Pereversev S. , Yakshinsky B. , Madey T. , Rogers J. A. , Gershenson M. E.
Published: August 2005

Using single-crystal organic field-effect transistors with the conduction channel exposed to environmental agents, we have observed generation of electronic defects at the organic surface in the high-vacuum environment. Rapid decrease of the source–drain current of an operating device is observed upon exposure of the channel to the species generated by high-vacuum gauges. We attribute this effect to interaction of the organic surface with electrically neutral free radicals produced in the process of hydrocarbon cracking on hot filaments with a relatively low activation energy Ea∼2.5eV (240kJ∕mol). The reported results might be important for optimizing the high-vacuum processes of fabrication and characterization of a wide range of organic and molecular electronic devices.
All-polymer ferroelectric transistors
Authors: Gelinck G. H. , Marsman A. W. , Touwslager F. J. , Setayesh S. , de Leeuw D. M. , Naber R. C. G. , Blom P. W. M.
Published: August 2005

We demonstrate thin-film ferroelectric transistors, made entirely from organic materials that are processed from solution. The devices consist of thin ferroelectric poly(vinylidene fluoride/trifluoroethylene) films sandwiched between electrodes made of conducting poly(3,4-ethylenedioxythiophene) stabilized with polystyrene-4-sulphonic acid. On top of this stack, an organic semiconductor is applied. The ferroelectric transistors, constructed using unipolar p- or n-type semiconductor channels, have remnant current modulations of ∼103 with a retention time of hours. They can be switched in 0.1–1ms at operating voltages less than 10V.
Structural and magnetic properties of epitaxially grown MnAs films on GaAs(110)
Authors: Kolovos-Vellianitis D. , Herrmann C. , Däweritz L. , Ploog K. H.
Published: August 2005

MnAs films were grown by molecular beam epitaxy (MBE) on GaAs(110) substrates, since this orientation was recently identified as promising for the increase of spin lifetimes in semiconductor heterojunctions, which is of interest in spin injection experiments. A single epitaxial orientation was revealed for the MnAs films which consist of both the ferromagnetic, hexagonal α-MnAs and the paramagnetic, orthorhombic β-MnAs phase at room temperature. This phase coexistence could be imaged as a well ordered stripe pattern, whose periodicity depends on the film thickness. The study of the ferromagnetic properties shows a strong influence of the film thickness on the measured coercive fields and saturation magnetizations.
Electrically injected spin-polarized vertical-cavity surface-emitting lasers
Authors: Holub M. , Shin J. , Chakrabarti S. , Bhattacharya P.
Published: August 2005

We report the design, fabrication, and characterization of an electrically injected, spin-polarized, vertical-cavity surface-emitting laser. We have demonstrated spin injection from the ferromagnetic semiconductor (Ga,Mn)As into In0.2Ga0.8As∕GaAs quantum wells, spin transport across a distance of ∼0.25μm for temperatures ranging from 80to105K, and spin detection through optical polarization measurements with coherent light emission. Controlled switching between right- and left-elliptically polarized modes is achieved with a maximum degree of circular polarization of 4.6% measured at 80K.
Quasi-aligned ZnO nanotubes grown on Si substrates
Authors: Xu W. Z. , Ye Z. Z. , Ma D. W. , Lu H. M. , Zhu L. P. , Zhao B. H. , Yang X. D. , Xu Z. Y.
Published: August 2005

Quasi-aligned ZnO nanotubes have been grown on silicon substrates by metalorganic chemical vapor deposition without using any catalyst. Two kinds of ZnO nanotubular structures were found: Nanotubes with single walls and nanotubes with double walls. The nanotubes were grown along the [001] direction. Room-temperature photoluminescence measurements of the ZnO nanotubes indicate strong ultraviolet emission and weak green emission. A new growth mode for these ZnO nanotubes is proposed, which can be used to prepare other nanotubular structures.
Liquid-crystal beam steering device with a photopolymer prism
Authors: Park Jae-Hong , Khoo Iam Choon
Published: August 2005

We report on liquid-crystal (LC) beam steering device with a photopolymer prism produced by ultraviolet exposure. The method for producing the prism is based on the diffusion process of the prepolymer during photopolymerization. No chemical etching is needed. Our LC device gives complete single-order diffraction and a controllable steering over ∼1° with an applied ac voltage of 5 V. The experimental data, together with the simulation results with respect to electrical steering properties, are presented.
Time-resolved photoluminescence study of the stimulated emission in ZnO nanoneedles
Authors: Kwok W. M. , Djurišić A. B. , Leung Y. H. , Chan W. K. , Phillips D. L.
Published: August 2005

ZnO nanoneedles were fabricated by thermal evaporation of Zn nanoparticles at 800 °C and atmospheric pressure. The samples showed strong ultraviolet photoluminescence and weak orange defect luminescence. Time-resolved photoluminescence (TRPL) was measured using the Kerr-gated fluorescence technique in order to probe the ultrafast carrier dynamics in exciton-exciton scattering and electron hole plasma (EHP) regimes. In both regimes, the decay time of the photoluminescence is very fast (∼1ps). Even though no structure is detected in the time-integrated spectra of the EHP emission, the TRPL reveals the coexistence of the excitons and free carriers. Possible reasons for the observed phenomena are discussed.
Two-color pump–probe experiments on silicon inverse opals
Authors: Becker C. , Linden S. , von Freymann G. , Wegener M. , Tétreault N. , Vekris E. , Kitaev V. , Ozin G. A.
Published: August 2005

We present time-resolved pump–probe experiments in a transmission geometry using off-resonant excitation on very high-quality silicon inverse opals. We show that the nonlinear optical response can drastically be modified by tempering of the sample. The as-grown samples are dominated by an absorptive response with recovery times as short as one picosecond. For the tempered samples, both the relaxation and the scattering times increase, leading to a prominent dispersive response. Based on simple calculations using the Drude model, we estimate corresponding refractive index changes as large as Δn=−0.5+i0.07.
Gate-length and drain-voltage dependence of thermal drain noise in advanced metal-oxide-semiconductor-field-effect transistors
Authors: Hosokawa S. , Navarro D. , Miura-Mattausch M. , Mattausch H. J. , Ohguro T. , Iizuka T. , Taguchi M. , Kumashiro S. , Miyamoto S.
Published: August 2005

The high thermal-drain-noise coefficient γ for short-channel metal-oxide-semiconductor-field-effect transistors (MOSFETs) has little to do with hot electrons or velocity saturation, but is determined by the potential gradient along the channel. Consequently, an analytical model for circuit simulation, derived by integration with the surface-potential distribution along the channel, reproduces measured noise characteristics without additional fitting parameters. Furthermore, experimental and theoretical data suggest a fixed relation between the source-drain voltage (Vds) gradients of γ under the saturation condition and the threshold-voltage shift (ΔVth) relative to a long-channel MOSFET.
Hildebrand solubility parameters measurement via sessile drops evaporation
Authors: Fang Xiaohua , Li Bingquan , Sokolov Jonathan C. , Rafailovich Miriam H. , Gewaily Dina
Published: August 2005

A method for the measurement of Hildebrand solubility parameter has been developed. This method was based on the measurement of the sessile drop contact angle and contact base width during its evaporation. Experimental results showed that this method is accurate and insensitive to the measurement conditions. The major advantages of this method are that it is time efficient and requires a small amount of liquid (microliter) for the measurement.
Persistent spectral hole burning in europium-doped sodium tellurite glass
Authors: Pulluru Chandra R. , Kalluru Rajamohan R. , Reddy B. Rami , Konovalova Tatyana A. , Kispert Lowell D.
Published: August 2005

We have prepared sodium tellurite glasses doped with europium. Emission intensity of the europium-doped glass is at least 500× more than that of the undoped glass. Fluorescence features exhibited dependence on the pump laser wavelength. Persistent spectral hole burning was observed in the F07→D05 transition of Eu3+. Multiple hole burning was possible even if the chemicals were melted in ambient air to make the glass. The hole burning mechanism is also explained. Electron spin resonance measurements confirmed the existence of defect centers.
Performance of a diamond x-ray sensor fabricated with metal-less graphitic contacts
Authors: Sellin P. J. , Galbiati A.
Published: August 2005

We report the x-ray photocurrent response of a coplanar chemical vapor deposition diamond detector fabricated using a metal-less graphitic ohmic contact. Ion implantation of 70 keV boron ions to a dose of 2×1016cm−2 was performed through a patterned photoresist to produce a coplanar graphitic contact structure. The device photocurrent showed a fast response to pulsed x-ray irradiation, and showed no evidence of photocurrent persistence that is observed in devices fabricated using metal Schottky contacts. The graphite-contact device also showed no extrinsic photoconductivity when illuminated with white light.
Atomic force microscopy reveals the stoichiometry and subunit arrangement of 5-HT3receptors
Authors: Barrera Nelson P. , Herbert Paul , Henderson Robert M. , Martin Ian L. , Edwardson J. Michael
Published: August 2005

The 5-HT3receptor is a cation-selective ligand-gated ion channel of the Cys-loop superfamily. The receptor is an important therapeutic target, with receptor antagonists being widely used as antiemetics in cancer therapy. The two known receptor subunits, A and B, form homomeric 5-HT3Areceptors and heteromeric 5-HT3A/Breceptors. The heteromeric receptor has the higher single-channel conductance and more closely mimics the properties of the native receptor. We have used atomic force microscopy to study the architecture of 5-HT3Aand 5-HT3A/Breceptors. We engineered different epitope tags onto the A- and B-subunits and imaged receptors that were doubly liganded by anti-epitope antibodies. We found that, for the 5-HT3A/Breceptor, the distribution of angles between antibodies against the A-subunit had a single peak at ≈144°, whereas the distribution for antibodies against the B-subunit had two peaks at ≈72° and 144°. Our results indicate that the subunit stoichiometry is 2A:3B and that the subunit arrangement around the receptor rosette is B-B-A-B-A. This arrangement may account for the difference between the agonist Hill coefficients and the single-channel conductances for the two types of receptor.
Distinct mechanisms of
cis-syn
thymine dimer bypass by Dpo4 and DNA polymerase η
Authors: Johnson Robert E. , Prakash Louise , Prakash Satya
Published: August 2005

UV-light-induced cyclobutane pyrimidine dimers (CPDs) present a severe block to synthesis by replicative DNA polymerases (Pols), whereas Polη promotes proficient and error-free replication through CPDs. Although the archael Dpo4, which, like Polη, belongs to the Y family of DNA Pols, can also replicate through a CPD, it is much less efficient than Polη. The x-ray crystal structure of Dpo4 complexed with either the 3′-thymine (T) or the 5′ T of a
cis-syn
TT dimer has indicated that, whereas the 3′ T of the dimer forms a Watson–Crick base pair with the incoming dideoxy ATP, the 5′ T forms a Hoogsteen base pair with the dideoxy ATP in
syn
conformation. Based upon these observations, a similar mechanism involving Hoogsteen base pairing of the 5′ T of the dimer with the incoming A has been proposed for Polη. Here we examine the mechanisms of CPD bypass by Dpo4 and Polη using nucleotide analogs that specifically disrupt the Hoogsteen or Watson–Crick base pairing. Our results show that both Dpo4 and Polη incorporate dATP opposite the 5′ T of the CPD via Watson–Crick base pairing and not by Hoogsteen base pairing. Furthermore, opposite the 3′ T of the dimer, the two Pols differ strikingly in the mechanisms of dATP incorporation, with Dpo4 incorporating opposite an abasic-like intermediate and Polη using the normal Watson–Crick base pairing. These observations have important implications for the mechanisms used for the inefficient vs. efficient bypass of CPDs by DNA Pols.
A funneled energy landscape for cytochromecdirectly predicts the sequential folding route inferred from hydrogen exchange experiments
Authors: Weinkam Patrick , Zong Chenghang , Wolynes Peter G.
Published: August 2005

Proteins fold through a variety of mechanisms. For a given protein, folding routes largely depend on the protein's stability and its native-state geometry, because the landscape is funneled. These ideas are corroborated for cytochromecby using a coarse-grained topology-based model with a perfect funnel landscape that includes explicit modeling of the heme. The results show the importance of the heme as a nucleation site and explain the observed hydrogen exchange patterns of cytochromecwithin the context of energy landscape theory.
Structural determinants of agonist-specific kinetics at the ionotropic glutamate receptor 2
Authors: Holm Mai Marie , Lunn Marie-Louise , Traynelis Stephen F. , Kastrup Jette S. , Egebjerg Jan
Published: August 2005

Glutamate receptors (GluRs) are the most abundant mediators of the fast excitatory neurotransmission in the human brain. Agonists will, after activation of the receptors, induce different degrees of desensitization. The efficacy of agonists strongly correlates with the agonist-induced closure of the ligand-binding domain. However, the differences in desensitization properties are less well understood. By using high-resolution x-ray structure of the GluR2 flop (GluR2o) ligand-binding core protein in complex with the partial glutamate receptor agonist (
S
)-2-amino-3-(3-hydroxy-5-
tert
-butyl-4-isothiazolyl)propionic acid [(
S
)-thio-ATPA], we show that (
S
)-thio-ATPA induces an 18° closure of the binding core similar to another partial agonist, (
S
)-2-amino-3-(4-bromo-3-hydroxy-5-isoxazolyl)propionic acid [(
S
)-Br-HIBO]. Despite the similar closure of the ligand-binding domain, we find in electrophysiological studies that (
S
)-thio-ATPA induced a 6.4-fold larger steady-state current than (
RS
)-Br-HIBO, and rapid agonist applications show that (
S
)-thio-ATPA induces a 3.6-fold higher steady-state/peak ratio and a 2.2-fold slower desensitization time constant than (
RS
)-Br-HIBO. Structural comparisons reveal that (
S
)-Br-HIBO, but not (
S
)-thio-ATPA, induces a twist of the ligand-binding core compared with the apostructure, and the agonist-specific conformation of Leu-650 correlates with the different kinetic profiles pointing at a key role in defining the desensitization kinetics. We conclude that, especially for intermediate efficacious agonists, the desensitization properties are influenced by additional ligand-induced factors beyond domain closure.
The fusion of bone-marrow-derived proinsulin-expressing cells with nerve cells underlies diabetic neuropathy
Authors: Terashima Tomoya , Kojima Hideto , Fujimiya Mineko , Matsumura Kazuhiro , Oi Jiro , Hara Manami , Kashiwagi Atsunori , Kimura Hiroshi , Yasuda Hitoshi , Chan Lawrence
Published: August 2005

Diabetic neuropathy is the most common microvascular complication of diabetes. Here we show that, in streptozotocin-induced diabetic rodents with neuropathy, a subpopulation of bone-marrow-derived cells marked by proinsulin expression migrates to and fuses with neurons in the sciatic nerve and dorsal root ganglion (DRG), resulting in neuronal dysfunction and accelerated apoptosis. The absence or presence of proinsulin expression, which identifies the fusion cells, and not the disease state (nondiabetic vs. diabetic) of the rats from which the DRG neurons are isolated determines whether the DRG neurons show normal or abnormal calcium homeostasis and apoptosis. These results suggest that bone-marrow-derived cells may play an important role in the pathogenesis of diabetic complications.
Enhanced NF-κB activation and cellular function in macrophages lacking IκB kinase 1 (IKK1)
Authors: Li Qiutang , Lu Qingxian , Bottero Virginie , Estepa Gabriela , Morrison Lisa , Mercurio Frank , Verma Inder M.
Published: August 2005

IκB kinase (IKK) complex plays a key regulatory role in macrophages for NF-κB activation during both innate and adaptive immune responses. Because IKK1–/–mice died at birth, we differentiated functional macrophages from embryonic day 15.5 IKK1 mutant embryonic liver. The embryonic liver-derived macrophage (ELDM) showed enhanced phagocytotic clearance of bacteria, more efficient antigen-presenting capacity, elevated secretion of several key proinflammatory cytokines and chemokines, and known NFκB target genes. Increased NFκB activity in IKK1 mutant ELDM was the result of prolonged degradation of IκBα in response to infectious pathogens. The delayed restoration of IκBα in pathogen-activated IKK1–/–ELDM was a direct consequence of uncontrolled IKK2 kinase activity. We hypothesize that IKK1 plays a checkpoint role in the proper control of IκBα kinase activity in innate and adaptive immunity.
Platinum anticancer drug damage enforces a particular rotational setting of DNA in nucleosomes
Authors: Danford Andrew J. , Wang Dong , Wang Qun , Tullius Thomas D. , Lippard Stephen J.
Published: August 2005

We constructed two site-specifically modified nucleosomes containing an intrastrand
cis
-{Pt(NH
3
)
2
}
2+
1,3-d(GpTpG) cross-link, similar to one formed by the anticancer drugs carboplatin and cisplatin on DNA, and investigated their structures by hydroxyl radical footprinting and exonuclease III digestion. Hydroxyl radical footprinting demonstrated that the presence of the platinum cross-link selects out a specific rotational setting of DNA on the histone octamer core in each of two reconstituted nucleosomes in which the platinum positions differ by half a DNA helical turn. The {Pt(NH
3
)
2
}
2+
cross-link is situated in a structurally similar location, with the undamaged strand projecting outward, forcing the DNA to adopt opposite rotational settings in its wrapping around the histone octamer in the two nucleosomes. Enzymatic digestion by exonuclease III of the nucleosome substrates revealed that the platinum cross-link affects the translational positioning of the DNA, forcing it into an asymmetric arrangement with respect to the core histone proteins. We suggest that these phasing phenomena may be central to the recognition and processing of platinum-DNA adducts in cancer cells treated with these drugs and possibly may be common to other DNA damaging events.
G protein-coupled receptor signaling through Gq and JNK negatively regulates neural progenitor cell migration
Authors: Mizuno Norikazu , Kokubu Hiroshi , Sato Maiko , Nishimura Akiyuki , Yamauchi Junji , Kurose Hitoshi , Itoh Hiroshi
Published: August 2005

In the early development of the central nervous system, neural progenitor cells divide in an asymmetric manner and migrate along the radial glia cells. The radial migration is an important process for the proper lamination of the cerebral cortex. Recently, a new mode of the radial migration was found at the intermediate zone where the neural progenitor cells become multipolar and reduce the migration rate. However, the regulatory signals for the radial migration are unknown. Using the migration assay
in vitro
, we examined how neural progenitor cell migration is regulated. Neural progenitor cells derived from embryonic mouse telencephalon migrated on laminin-coated dishes. Endothelin (ET)-1 inhibited the neural progenitor cell migration. This ET-1 effect was blocked by BQ788, a specific inhibitor of the ETB receptor, and by the expression of a carboxyl-terminal peptide of Gαq but not Gαi. The expression of constitutively active mutant of Gαq, GαqR183C, inhibited the migration of neural progenitor cells. Moreover, the inhibitory effect of ET-1 was suppressed by the c-Jun N-terminal kinase (JNK) inhibitor SP600125 and the expression of the JNK-binding domain of JNK-interacting protein-1, a specific inhibitor of the JNK pathway. Using the slice culture system of embryonic brain, we demonstrated that ET-1 and the constitutively active mutant of Gαq caused the retention of the neural progenitor cells in the intermediate zone and JNK-binding domain of JNK-interacting protein-1 abrogated the effect of ET-1. These results indicated that G protein-coupled receptor signaling negatively regulates neural progenitor cell migration through Gq and JNK.
Asymmetry in angular rigidity of hydrogen-bonded complexes
Authors: Yu Zhenhong , Klemperer William
Published: August 2005

The asymmetry in angular rigidity of the proton donor and proton acceptor of hydrogen-bonded hydrogen fluoride binary complexes is investigated. The intermolecular bending frequency of HF, as the proton donor, is linearly proportional to the square root of the dissociation energy, whereas that of the proton acceptor is always much lower. The asymmetry, measured by the ratio of bending elastic constants of HF to that of the proton acceptor, is generally >2, and varies pronouncedly with the acceptors reaching values >20. Molecules with nitrogen as the bridged acceptor atom show an angular rigidity nearly one order of magnitude greater than the group with oxygen as the proton acceptor.
Cyanidin-3-O-β-glucopyranoside, a natural free-radical scavenger against aflatoxin B1- and ochratoxin A-induced cell damage in a human hepatoma cell line (Hep G2) and a human colonic adenocarcinoma cell line (CaCo-2)
Authors: Guerra M. C. , Galvano F. , Bonsi L. , Speroni E. , Costa S. , Renzulli C. , Cervellati R.
Published: August 2005

Recent findings have suggested that oxidative damage might contribute to the cytotoxicity and carcinogenicity of aflatoxin B1 (AFB1). Induction of oxidative stress also plays an important role in the toxicity of another mycotoxin, ochratoxin A (OTA). In the present study, the protective effect of cyanidin-3-O-β-glucopyranoside (C-3-G; an anthocyanin contained in oranges, blackberries, strawberries and cranberries) against AFB1- and OTA-induced cytotoxicity was investigated in a human hepatoma-derived cell line (Hep G2) and a human colonic adenocarcinoma cell line (CaCo-2). The ability of C-3-G to reduce the production of reactive oxygen species (ROS), the inhibition of protein and DNA synthesis and the apoptosis caused by the two mycotoxins was also investigated in both cell lines. Our experiments proved the significant cytoprotective effect of C-3-Gin vitroagainst OTA- and AFB1-induced cell damage. In particular, 24 h of pretreatment with 50 μm-C-3-G inhibited the cytotoxicity of 10 μm-AFB1 (by 35 %) and of 10 μm-OTA (by 25 %) in Hep G2 cells (P<0·001) and of 10 μm-AFB1 (by 10 %,P<0·01) and of 10 μm-OTA (by 14 %,P<0·05) in CaCo-2 cells. Moreover, 50 μm-C-3-G attenuated ROS production induced by the two toxins in both cell lines (P<0·05). Inhibition of DNA and protein synthesis induced by the mycotoxins was counteracted by pretreatment with the antioxidant at 50 μm. Similarly, apoptotic cell death was prevented as demonstrated by a reduction of DNA fragmentation and inhibition of caspase-3 activation. Thein vitrofree-radical scavenging capacity of the anthocyanin was tested with the Briggs–Rauscher oscillating reaction. This system works at pH approximately 2. The results showed good scavenging power, in accordance with the observed inhibition of ROS production.
Parenteral nutrition providing a restricted amount of linoleic acid in severely burned patients: a randomised double-blind study of an olive oil-based lipid emulsion v. medium/long-chain triacylglycerols
Authors: García-de-Lorenzo A. , Denia R. , Atlan P. , Martinez-Ratero S. , Le Brun A. , Evard D. , Bereziat G.
Published: August 2005

It has been claimed that lipid emulsions with a restricted linoleic acid content can improve the safety of total parenteral nutrition (TPN). The tolerability of TPN and its effects on the metabolism of fatty acids were assessed in this prospective, double-blind, randomised study comparing an olive/soyabean oil long-chain triacylglycerol (LCT) with a medium-chain triacylglycerol (MCT)/LCT; 50:50 (w) based lipid emulsion in two groups (O and M, respectively; eleven per group) of severely burned patients. After resuscitation (48–72 h), patients received TPN providing 147 kJ/kg per d (35 kcal/kg per d) with fat (1·3 g/kg per d) for 6 d Plasma fatty acids, laboratory parameters including liver function tests, and plasma cytokines were assessed before and after TPN. Adverse events encountered during TPN and the clinical outcomes of patients within the subsequent 6 months were recorded. With both lipid emulsions, the conversion of linoleic acid in its higher derivatives (di-homo-γ-linolenic acid) improved and essential fatty acid deficiency did not appear. Abnormalities of liver function tests occurred more frequently in the M (nine) than in the O (three) group (P=0·04, Suissa–Shuster test). Seven patients (four from group O and three from group M) died as a consequence of severe sepsis 3–37 d after completion of the 6 d TPN period. When compared with the surviving patients, those who died were older (P=0·01) and hyperglycaemic at baseline (P<0·001), and their plasma IL-6 levels continued to increase (P<0·04). Although fatty acid metabolism and TPN tolerability were similar with both lipid emulsions, the preservation of liver function noted with the use of the olive oil-based lipid emulsions deserves confirmation.
The Mediterranean Eating in Scotland Experience project: evaluation of an Internet-based intervention promoting the Mediterranean diet
Authors: Papadaki Angeliki , Scott Jane A.
Published: August 2005

A 6-month intervention study with a quasi-experimental design was conducted to evaluate the effectiveness of an Internet-based, stepwise, tailored-feedback intervention promoting four key components of the Mediterranean diet. Fifty-three (intervention group) and nineteen (control group) healthy females were recruited from the Universities of Glasgow and Glasgow Caledonian, Scotland, respectively. Participants in the intervention group received tailored dietary and psychosocial feedback and Internet nutrition education over a 6-month period, while participants in the control group were provided with minimal dietary feedback and general healthy-eating brochures. Internet education was provided via an innovative Mediterranean Eating Website. Dietary changes were assessed with 7 d estimated food diaries at baseline and 6 months, and data were analysed to calculate the Mediterranean Diet Score, a composite score based on the consumption of eight components of the traditional Mediterranean diet. The ‘intention-to-treat’ analyses showed that, at 6 months, participants in the intervention group had significantly increased their intake of vegetables, fruits and legumes, as well as the MUFA:saturated fatty acid ratio in their diet, and had significantly increased plasma HDL-cholesterol levels and a reduced ratio of total:HDL-cholesterol. Participants in the control group increased their intake of legumes but showed no other favourable significant changes compared with baseline. This Internet-based, tailored-feedback intervention promoting components of the Mediterranean diet holds promise in encouraging a greater consumption of plant foods, as well as increasing monounsaturated fat and decreasing saturated fat in the Scottish diet; it also shows that the Mediterranean diet can be adopted by healthy individuals in northern European countries.
The absorption, metabolism and excretion of flavan-3-ols and procyanidins following the ingestion of a grape seed extract by rats
Authors: Tsang Catherine , Auger Cyril , Mullen William , Bornet Aurélie , Rouanet Jean-Max , Crozier Alan , Teissedre Pierre-Louis
Published: August 2005

Rats were fed a grape seed extract (GSE) containing (+)-catechin, (−)-epicatechin and dimers, trimers, tetramers and polymeric procyanidins. Liver, kidney, brain and gastrointestinal (GI) tract together with plasma, urine and faeces were collected over a 24 h period and their flavan-3-ol content was analysed by HPLC with tandem mass spectrometry and diode array detection. Small amounts of the GSE flavan-3-ols moved out of the stomach and into the duodenum/jejunum, and to a greater extent the ileum 1 h after ingestion, and into the caecum after 2 h with relatively small amounts being detected in the colon after 3 h. The GI tract contained the parent GSE flavan-3-ols and procyanidins with only trace amounts of metabolites and there were no indications that proanthocyanidins were depolymerised in the GI tract releasing monomeric flavan-3-ols. Plasma contained exclusively catechin glucuronides and methylated glucuronide metabolites which were also detected in the liver and kidneys. These metabolites were also present in urine together with sulphated metabolites and low amounts of the procyanidin dimers B1, B2, B3 and B4 as well as the trimer C2 and an unknown GSE trimer. The amounts of (+)-catechin and (−)-epicatechin metabolites excreted in urine relative to the quantity of the monomers ingested were 27 and 36 %, respectively, after 24 h. This is similar to the levels of urinary excretion reported to occur by other investigators after feeding (−)-epicatechin to rats and provides further, albeit indirect, evidence that the procyanidin oligomers in the GSE were not depolymerised to monomers to any extent after ingestion. No convincing analytical data were obtained for the presence of flavan-3-ol metabolites in the brain.
Effect of site of starch digestion on portal nutrient net fluxes in steers
Authors: Nozière Pierre , Rémond Didier , Lemosquet Sophie , Chauveau Béatrice , Durand Denys , Poncet Claude
Published: August 2005

Processing of maize grain is known to modulate the site of starch digestion, thus the nature and amount of nutrients delivered for absorption. We assessed the effect of site of starch digestion on nutrient net fluxes across portal-drained viscera (PDV). Three steers, fitted with permanent digestive cannulas and blood catheters, successively received two diets containing 35 % starch as dent maize grain. Diets differed according to maize presentation: dry and cracked (by-pass, BP)v. wet and ground (control, C). Ruminal physicochemical parameters were not significantly affected. Between C and BP, the decrease in ruminal starch digestion was compensated by an increase in starch digestion in the small intestine. The amount of glucose and soluble α-glucoside reaching the ileum was not affected. The amount of glucose disappearing in the small intestine increased from 238 to 531 g/d between C and BP, but portal net flux of glucose remained unchanged (−97 g/d). The portal O2consumption and net energy release were not significantly affected, averaging 16 % and 57 % of metabolizable energy intake, respectively. The whole-body glucose appearance rate, measured by jugular infusion of [6, 6-2H2]glucose, averaged 916 g/d. The present study shows that the increase in the amount of glucose disappearing in the small intestine of conventionally fed cattle at a moderate intake level induces no change in portal net flux of glucose, reflecting an increase in glucose utilization by PDV. That could contribute to the low response of whole-body glucose appearance rate observed at this moderate level of intestinal glucose supply.
Incorporation ofcis-9,trans-11 conjugated linoleic acid and vaccenic acid (trans-11 18:1) into plasma and leucocyte lipids in healthy men consuming dairy products naturally enriched in these fatty acids
Authors: Burdge Graham C. , Tricon Sabine , Morgan Rebecca , Kliem Kirsty E. , Childs Caroline , Jones Emma , Russell Jennifer J. , Grimble Robert F. , Williams Christine M. , Yaqoob Parveen , Calder Philip C.
Published: August 2005

The present study investigated whether consuming dairy products naturally enriched incis-9,trans-11 (c9,t11) conjugated linoleic acid (CLA) by modification of cattle feed increases the concentration of this isomer in plasma and cellular lipids in healthy men. The study had a double-blind cross-over design. Subjects aged 34–60 years consumed dairy products available from food retailers for 1 week and then either control (0·17 gc9,t11 CLA/d; 0·31 gtrans-vaccenic acid (tVA)/d) or CLA-enriched (1·43 gc9,t11 CLA/d; 4·71 gtVA/d) dairy products for 6 weeks. After 7 weeks washout, this was repeated with the alternate products.c9,t11 CLA concentration in plasma lipids was lower after consuming the control products, which may reflect the two-fold greaterc9,t11 CLA content of the commercial products. Consuming the CLA-enriched dairy products increased thec9,t11 CLA concentration in plasma phosphatidylcholine (PC) (38%;P=0·035), triacylglycerol (TAG) (22%;P<0·0001) and cholesteryl esters (205%;P<0·0001), and in peripheral blood mononuclear cells (PBMC) (238%;P<0·0001), whiletVA concentration was greater in plasma PC (65%;P=0·035), TAG (98%;P=0·001) and PBMC (84%;P=0·004). Overall, the present study shows that consumption of naturally enriched dairy products in amounts similar to habitual intakes of these foods increased thec9,t11 CLA content of plasma and cellular lipids.
The reliability of force platform data from trotting horses
Authors: Lynch JA , Clayton HM , Mullineaux DR
Published: August 2005

The aim of the present study was to quantify the inter-day reliability of force platform data from horses at the trot. The subjects were ten horses judged to be sound on the basis of clinical evaluation and similarity of ground reaction force peaks of left and right limbs. The same handler trotted horses in hand for four consecutive days over a force platform at their natural and comfortable velocity between 2.70 and 3.60 m s−1. For each horse, velocity was controlled in a range of±0.15 m s−1. Five contacts per limb were recorded on each day. Custom-written code in MATLAB was used to smooth the data and time-normalize to 101 data points. The agreement boundary was used to determine the reliability of seven force variables. Stance duration, peak vertical force and vertical impulse were the most reliable variables (<10% variability in the mean), while peak braking and propulsive forces and impulses had larger variation across the three days (>20% variability in the mean). Variables with low variability may require fewer animals, trials and days to obtain accurate data while maintaining adequate statistical power. These results may act both as a reference when studying variability in lame horses and as a guide for planning future equine kinetic studies.
Acute progressive resistance exercise alters intracardiac pressure in ponies
Authors: McKeever KH , Alway SE , Farris JW , Hinchcliff KW , Lombardo JA
Published: August 2005

Five male ponies (3–6 years, 208±11 kg) were used to examine the haemodynamic effects of resistance exercise. The experiment consisted of a 30 min catheterization period and a 15 min equilibration period followed by the test. Initially, the ponies stood quietly on a treadmill for collection of 5 min of baseline data. They then walked at 1.9 m s−1for 1 min sets while carrying 0 kg, 67 kg or 134 kg of weight loaded on the saddle area. Weights were applied in a randomized order using a chain hoist and sling. The ponies rested unloaded for 2 min between sets and all cardiovascular parameters returned to baseline before beginning the next set. Haemodynamic measurements (heart rate (HR), carotid artery systolic (SP), diastolic (DP), pulse (PP) and mean pressure (MAP), right atrial pressure (RAP), right ventricular pressure (RVP) and right ventricular maximum rate of pressure rise (dP/dtmax)) were recorded continuously and data collected during the last 18 s of each set were averaged and analysed. HR increased (P<0.05) with unloaded exercise (201%) and with increases in load (252 and 271% at 67 and 134 kg, respectively). RAP increased (P<0.05) with exercise, with differences (P<0.05) between the response to the 0 kg (66%), 67 kg (121%) and 134 kg (138%) loads. RVP increased (P<0.05) incrementally with load during exercise (58, 110 and 136%, respectively), with differences (P<0.05) between 0versus67 kg and 67versus134 kg. Right ventricular dP/dtmaxincreased (P<0.05) incrementally and showed differences (P<0.05) between loads (131, 191 and 252% at 0, 67 and 134 kg, respectively). There were increases (P<0.05) in MAP (20%), SP (20%) and DP (27) with exercise, but no difference (P>0.05) between the response to 67versus134 kg load (43 and 51%; 40 and 46%; 49 and 62, respectively). Pulse pressure did not change (P>0.05) from baseline values. These data suggest that resistance exercise in the form of weight carried increases intraventricular pressure through a significant increase in both cardiac pre-load and after-load.
Time course and magnitude of fluid and electrolyte shifts during recovery from high-intensity exercise in Standardbred racehorses
Authors: Waller Amanda , Lindinger Michael I
Published: August 2005

The present study characterized the fluid and electrolyte shifts that occur in Standardbred racehorses during recovery from high-intensity exercise. Jugular venous blood was sampled from 13 Standardbreds in racing condition, at rest and for 2 h following a high-intensity training workout. Total body water (TBW), extracellular fluid volume (ECFV) and plasma volume (PV) were measured at rest using indicator dilution techniques (D2O, thiocyanate and Evans Blue, respectively). Changes in TBW were assessed from measures of body mass, and changes in PV and ECFV were calculated from changes in plasma protein concentration. Exercise resulted in a 26.9% decrease in PV. At 10 min of recovery TBW and ECFV were decreased by 2.2% and 16.5% respectively, while intracellular fluid volume was increased by 7.1%. There was a continued loss of fluid due to sweating throughout the recovery period such that TBW was decreased by 3.9% at 90 min of recovery. This decrease in TBW was nearly equally partitioned between the extracellular and intracellular fluid compartments. Plasma Na+and Cl−contents were decreased at 1 min of recovery, but not different from rest by 40 min of recovery. Plasma K+content at 1 min post exercise was not different from the pre-exercise value; however, by 5 min of recovery K+content was significantly decreased and it remained decreased throughout the recovery period. It is concluded that there are very rapid and large fluid and electrolyte shifts between body compartments during and after high-intensity exercise, and that full recovery of these shifts requires 90–120 min.
CEACAM engagement by human pathogens enhances cell adhesion and counteracts bacteria-induced detachment of epithelial cells
Authors: Muenzner Petra , Rohde Manfred , Kneitz Susanne , Hauck Christof R.
Published: August 2005

Exfoliation, which is the detachment of infected epithelial cells, is an innate defense mechanism to prevent bacterial colonization. Indeed, infection with Neisseria gonorrhoeae induced epithelial detachment from an extracellular matrix (ECM) substrate in vitro. Surprisingly, variants of N. gonorrhoeae that bind to human carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) failed to induce detachment and, instead, promoted enhanced host cell adhesion to the ECM. Microarray analysis revealed that CEACAM engagement by several human pathogens triggers expression of CD105. Blockage of CD105 expression by antisense oligonucleotides abolished infection-induced cell adhesion. The expression of full-length CD105 promoted cell adhesion to the ECM and was sufficient to prevent infection-induced detachment. The CD105-mediated increase in cell adhesion was dependent on the presence and function of integrin β1. CD105 expression did not elevate cellular integrin levels but caused a dramatic increase in the ECM-binding capacity of the cells, suggesting that CD105 affects integrin activity. The exploitation of CEACAMs to trigger CD105 expression and to counteract infection-induced cell detachment represents an intriguing adaptation of pathogens that are specialized to colonize the human mucosa.
Support for the immortal strand hypothesis: neural stem cells partition DNA asymmetrically in vitro
Authors: Karpowicz Phillip , Morshead Cindi , Kam Angela , Jervis Eric , Ramunas John , Cheng Vincent , van der Kooy Derek
Published: August 2005

The immortal strand hypothesis proposes that asymmetrically dividing stem cells (SCs) selectively segregate chromosomes that bear the oldest DNA templates. We investigated cosegregation in neural stem cells (NSCs). After exposure to the thymidine analogue 5-bromo-2-deoxyuridine (BrdU), which labels newly synthesized DNA, a subset of neural precursor cells were shown to retain BrdU signal. It was confirmed that some BrdU-retaining cells divided actively, and that these cells exhibited some characteristics of SCs. This asymmetric partitioning of DNA then was demonstrated during mitosis, and these results were further supported by real time imaging of SC clones, in which older and newly synthesized DNA templates were distributed asymmetrically after DNA synthesis. We demonstrate that NSCs are unique among precursor cells in the uneven partitioning of genetic material during cell divisions.
A SEMI‐PARAMETRIC MODEL FOR ASYMMETRIC INFORMATION IN HEALTH PLAN MARKETS
Authors: Bradley Ralph
Published: August 2005

Two sources of asymmetric information in health markets are adverse selection where only individuals know their illness probability and their preventive effort to reduce illness probabilities. This effort is not observed by insurers, and thus individuals cannot be adequately compensated for their effort. I investigate whether asymmetric information plays a role in health care markets through a semi‐parametric model that allows both adverse selection and preventive effort. I find that preventive effort plays a role in illness probabilities. If the United States implements universal health coverage, the currently uninsured population will exert less preventive effort, and their illness probabilities will increase. (JEL I11, C14)