bluuebunny/crossref_metadata_2025 huggingface dataset:
Interindividual reproducibility of glutamate quantification using 1.5‐T proton magnetic resonance spectroscopy
Authors: Jang Dong‐Pyo , Lee Jong‐Min , Lee Eun , Park Sangjin , Kim Jae‐Jin , Namkoong Kee , Yoon Kang‐Jun , Kim In‐Young , Kim Sun I.
Published: February 2005

The goal of this study was to measure the interindividual reproducibility of glutamate quantification in 1.5‐T 1H MRS of human brains. To determine the effective echo time (TE) for glutamate quantification, spectra from a phantom and 12 participants were obtained with TE = 30, 35, 40, and 144 ms (repetition time (TR) = 2000 ms and volume of interest = 4 cm3). The average Cramér–Rao lower bounds for glutamate quantification using LCModel was lowest in two experiments when TE = 40 ms.

Twenty‐one subjects participated in experiments that measured interindividual reproducibility of glutamate quantification. Spectra were acquired with TR = 6000 ms and TE = 40 ms. Results showed that the coefficients of variance were 11.0 and 13.1% in the anterior cingulate cortex and insula, respectively. This suggests that glutamate can be reproducibly measured from 1.5‐T 1H MRS with long TR, effective TE, and the LCModel. Magn Reson Med 53:708–712, 2005. © 2005 Wiley‐Liss, Inc.
Four‐phase single‐capillary stepwise model for kinetics in arterial spin labeling MRI
Authors: Li Ka‐loh , Zhu Xiaoping , Hylton Nola , Jahng Geon‐Ho , Weiner Michael W. , Schuff Norbert
Published: February 2005

An extended model for extracting measures of brain perfusion from pulsed arterial spin labeling (ASL) data while considering transit effects and restricted permeability of capillaries to blood water is proposed. We divided the time course of the signal difference between control and labeled images into four phases with respect to the arrival time of labeled blood water at the voxel of interest (tA), transit time through the arteries in the voxel (tex), and duration of the bolus of labeled spins (τ). Dividing the labeled slab of blood water into many discrete segments, and adapting numerical integration methods allowed us to conveniently model restricted capillary–tissue exchange based on a modified distributed parameter model. We compared this four‐phase single‐capillary stepwise (FPSCS) model with models that treat water as a freely diffusible tracer, using both simulations and experimental ASL brain imaging data at 1.5T from eight healthy subjects (24–80 years old). The FPSCS model yielded less errors in the least‐squares sense in fitting brain ASL data in comparison with freely diffusible tracer models of water (P = 0.055). These results imply that restricted permeability of capillaries to water should be considered when brain ASL data are analyzed. Magn Reson Med 53:511–518, 2005. Published 2005 Wiley‐Liss, Inc.
Molecular MR imaging of melanoma angiogenesis with ανβ3‐targeted paramagnetic nanoparticles
Authors: Schmieder Anne H. , Winter Patrick M. , Caruthers Shelton D. , Harris Thomas D. , Williams Todd A. , Allen John S. , Lacy Elizabeth K. , Zhang Huiying , Scott Michael J. , Hu Grace , Robertson J. David , Wickline Samuel A. , Lanza Gregory M.
Published: February 2005

Neovascularization is a critical component in the progression of malignant melanoma. The objective of this study was to determine whether ανβ3‐targeted paramagnetic nanoparticles can detect and characterize sparse ανβ integrin expression on neovasculature induced by nascent melanoma xenografts (∼30 mm3) at 1.5T. Athymic nude mice bearing human melanoma tumors were intravenously injected with αvβ3‐integrin‐targeted paramagnetic nanoparticles, nontargeted paramagnetic nanoparticles, or αvβ3‐targeted‐nonparamagnetic nanoparticles 2 hr before they were injected with αvβ3‐integrin‐targeted paramagnetic nanoparticles (i.e., in vivo competitive blockade) and imaged with MRI. Contrast enhancement of neovascularity in animals that received ανβ3‐targeted paramagnetic nanoparticles increased 173% by 120 min. Signal contrast with nontargeted paramagnetic nanoparticles was approximately 50% less than that in the targeted group (P < 0.05). Molecular MRI results were corroborated by histology. In a competitive cell adhesion assay, incubation of ανβ3‐expressing cells with targeted nanoparticles significantly inhibited binding to a vitronectin‐coated surface, confirming the bioactivity of the targeted nanoparticles. The present study lowers the limit previously reported for detecting sparse biomarkers with molecular MRI in vivo. This technique may be employed to noninvasively detect very small regions of angiogenesis associated with nascent melanoma tumors, and to phenotype and stage early melanoma in a clinical setting. Magn Reson Med 53:621–627, 2005. © 2005 Wiley‐Liss, Inc.
Noise reduction in multi‐slice arterial spin tagging imaging
Authors: St. Lawrence K. S. , Frank J. A. , Bandettini P. A. , Ye F. Q.
Published: February 2005

Attenuating the static signal in arterial spin tagging (ASSIST) was initially developed for 3D imaging of cerebral blood flow. To enable the simultaneous collection of cerebral blood flow and BOLD data, a multi‐slice version of ASSIST is proposed. As with the 3D version, this sequence uses multiple inversion pulses during the tagging period to suppress the static signal. To maintain background suppression in all slices, the multi‐slice sequence applies additional inversion pulses between slice acquisitions. The utility of the sequence was demonstrated by simultaneously acquiring ASSIST and BOLD data during a functional task and by collecting resting‐state ASSIST data over a large number of slices. In addition, the temporal stability of the perfusion signal was found to be 60% greater at 3 T compared to 1.5 T, which was attributed to the insensitivity of ASSIST to physiologic noise. Magn Reson Med 53:735–738, 2005. Published 2005 Wiley‐Liss, Inc.
Time‐resolved undersampled projection reconstruction magnetic resonance imaging of the peripheral vessels using multi‐echo acquisition
Authors: Du Jiang , Lu Aiming , Block Walter F. , Thornton Francis J. , Grist Thomas M. , Mistretta Charles A.
Published: February 2005

The hybrid projection reconstruction (PR) imaging provides high temporal resolution through an undersampled PR acquisition for the in‐plane dimensions and Cartesian slice encoding for the through‐plane dimension. The undersampling of projection data introduces streak artifact, which may severely compromise image quality. This study reports on a combination of multi‐echo acquisition with time‐resolved undersampled PR imaging and its application to peripheral magnetic resonance angiography. Multi‐echo acquisition improved imaging speed effectively, thereby reducing the undersampling streak artifact and improving the temporal resolution. The gradient distortion was reduced through gradient calibration and accurate k‐space trajectory measurement. Magn Reson Med 53:730–734, 2005. © 2005 Wiley‐Liss, Inc.
Electrochemical sensor for superoxide anion radical using polymeric iron porphyrin complexes containing axial 1‐methylimidazole ligand as cytochrome c mimics
Authors: Yuasa Makoto , Oyaizu Kenichi , Yamaguchi Aritomo , Ishikawa Masuhide , Eguchi Katsuya , Kobayashi Tomohiro , Toyoda Yuujiro , Tsutsui Satoshi
Published: February 2005

A needle‐type electrochemical sensor for the facile detection of superoxide anion radical (O) was devised using an electrodeposited film of a polymeric porphyrin complex attached to a carbon microelectrode which was placed in a stainless steel 18G needle tube as an auxiliary electrode. The sensing element was prepared by means of electropolymerization of bromoiron(III) meso‐ tetra(3‐thienyl)porphyrin in the presence of 1‐methylimidazole in CH2Cl2 containing 100 mM tetrabutylammonium perchlorate (TBAP) as a supporting electrolyte, which gave a smooth film of the corresponding polymer. The film was electrochemically active to give a redox response near −0.05 V versus Ag/AgCl due to the iron(II/III) couple. The microsensor was applied to detect O produced by xanthine oxidation catalyzed by xanthine oxidase. The amperometric response for O was monitored at an electrode potential of 0.5 V versus the auxiliary electrode in a 10 mM phosphate buffer. The microsensor displayed a high catalytic activity for the oxidation of O and showed a linear relationship between the current and the O concentration. Axial coordination of an imidazole ligand to the iron porphyrin center enhanced selectivity for O by impeding the undesired coordination of H2O2 that resulted from the dismutation of O. Copyright © 2005 John Wiley & Sons, Ltd.
Evaluation of thin‐film solar cell temperature coefficients for space applications
Authors: Liu Simon H. , Simburger Edward J. , Matsumoto James , Garcia Alexander , Ross Jasen , Nocerino John
Published: February 2005

At present, commercially available thin‐film photovoltaic cells are evaluated for terrestrial applications. To apply thin‐film photovoltaic cells for space applications, the assessment of the solar cell performance must be conducted in simulated space conditions. We investigated the temperature coefficients of theI–Vcharacteristics of thin‐film amorphous silicon (a‐Si) solar cells manufactured by Uni‐Solar and Iowa Thin Film Technologies, and CuInGaSe2(CIGS) solar cells manufactured by MicroSat Systems with simulated space solar radiation. The temperature coefficient of the thin‐film solar cells between temperatures of 15 and 100°C was measured with a temperature‐controlled vacuum plate. The vacuum plate ensures maximum thermal contact between the plate and the solar cell as well as reducing the thermal gradient in the solar cell. The vacuum plate also serves as a thermal reservoir that provides temperature stability during the performance evaluation when the solar cell is exposed to simulated sunlight radiation. An X‐25 sunlight simulator calibrated for AM0 conditions provides the necessary radiation in performance characterization of the thin‐film solar cell. TheI–Vcharacteristics of the solar cell were obtained at various temperatures to gain a thorough knowledge of the cell's performance at different temperatures. Copyright © 2005 John Wiley & Sons, Ltd.
Teaching addition and subtraction to first graders: A Chinese perspective
Authors: Zhou Zheng , Peverly Stephen T.
Published: February 2005

Cross‐cultural studies on mathematical cognition and education have suggested that curriculum and teaching have contributed to U.S. versus Asian differences in student performance; however, previous discussions of curriculum and teaching practices have been very general and have not focused on a detailed analysis of how mathematics concepts are taught and presented in textbooks. To address this limitation, this article focuses on the teaching of addition and subtraction to first‐grade students in China. We discuss how curriculum topics are arranged, how concrete and abstract mathematical knowledge are reconciled in learning these concepts, and how teachers facilitate children's conceptual understanding of the logic behind addition and subtraction procedures. Toward this end, we analyze a research‐based Chinese mathematics curriculum to highlight the sequencing of topics pertaining to addition and subtraction and the instructional practices used by teachers to help students develop an understanding of these concepts. The purpose of this article is not to suggest that other nations' curriculum and instructional practices ought to follow the Chinese model. Rather, we attempt to provide useful information about developing effective curriculum and instructional practices that could help young children make sense of the mathematics they learn in school. © 2005 Wiley Periodicals, Inc. Psychol Schs 42: 259–272, 2005.
Autism in China: From acupuncture to applied behavior analysis
Authors: Clark Elaine , Zhou Zheng
Published: February 2005

It has been only in the past decade that autism has been widely recognized among Chinese service providers. As a result, there are few professionals who are trained to treat the disorder. Although efforts are currently under way to determine the prevalence of autism in China, to date there are no reliable data that indicate the magnitude of the problem. There are no formalized education programs for children with autism and only a handful of treatment programs in larger city hospitals and private schools. Treatments range from herbal medicines and acupuncture to sensory integration training and, in rare instances, applied behavior analysis (ABA). This article provides an update on what is taking place in China for autism treatment, and the challenges that lie ahead as the Chinese Ministry of Education struggles to address the needs of children identified with the disorder. © 2005 Wiley Periodicals, Inc. Psychol Schs 42: 285–295, 2005.
The measurement of stressful events in Chinese college students
Authors: Li Hong , Lin Chong‐De , Bray Melissa A. , Kehle Thomas J.
Published: February 2005

The Chinese College Stress Scale was developed to ascertain stress in university students. Results suggested that the psychometric properties of the Chinese College Stress Scale were satisfactory. Overall, student stress was primarily related to academic, personal, and negative life events. Approximately 8% of Chinese students exhibited high stress associated with attending the university whereas 74% exhibited low stress, and approximately 18% did not report any stress. The general pattern of stressful college events is similar to that found in American studies; however, the rank order of stressors is somewhat different between these findings and the results of American studies. The top academic stressors for Chinese university students were low learning efficiency and competition among students whereas the top academic stressors for American students were related to examinations. Personal hassles for the Chinese students involved concerns that they were not being taught or educated properly and inadequate social skills. In contrast, the major personal stressors of American students were found to be associated with intimate relationships and parental conflicts. © 2005 Wiley Periodicals, Inc. Psychol Schs 42: 315–323, 2005.
Properties of integral membrane protein structures: Derivation of an implicit membrane potential
Authors: Ulmschneider Martin B. , Sansom Mark S.P. , Di Nola Alfredo
Published: February 2005

Distributions of each amino acid in the trans‐membrane domain were calculated as a function of the membrane normal using all currently available α‐helical membrane protein structures with resolutions better than 4 Å. The results were compared with previous sequence‐ and structure‐based analyses. Calculation of the average hydrophobicity along the membrane normal demonstrated that the protein surface in the membrane domain is in fact much more hydrophobic than the protein core. While hydrophobic residues dominate the membrane domain, the interfacial regions of membrane proteins were found to be abundant in the small residues glycine, alanine, and serine, consistent with previous studies on membrane protein packing. Charged residues displayed nonsymmetric distributions with a preference for the intracellular interface. This effect was more prominent for Arg and Lys resulting in a direct confirmation of the positive inside rule. Potentials of mean force along the membrane normal were derived for each amino acid by fitting Gaussian functions to the residue distributions. The individual potentials agree well with experimental and theoretical considerations. The resulting implicit membrane potential was tested on various membrane proteins as well as single trans‐membrane α‐helices. All membrane proteins were found to be at an energy minimum when correctly inserted into the membrane. For α‐helices both interfacial (i.e. surface bound) and inserted configurations were found to correspond to energy minima. The results demonstrate that the use of trans‐membrane amino acid distributions to derive an implicit membrane representation yields meaningful residue potentials. Proteins 2005. © 2005 Wiley‐Liss, Inc.
A multibody, whole‐residue potential for protein structures, with testing by Monte Carlo simulated annealing
Authors: Mayewski Stefan
Published: February 2005

A new multibody, whole‐residue potential for protein tertiary structure is described. The potential is based on the local environment surrounding each main‐chain α carbon (CA), defined as the set of all residues whose CA coordinates lie within a spherical volume of set radius in 3‐dimensional (3D) space surrounding that position. It is shown that the relative positions of the CAs in these local environments belong to a set of preferred templates. The templates are derived by cluster analysis of the presently available database of over 3000 protein chains (750,000 residues) having not more than 30% sequence similarity. For each template is derived also a set of residue propensities for each topological position in the template. Using lookup tables of these derived templates, it is then possible to calculate an energy for any conformation of a given protein sequence. The application of the potential to ab initio protein tertiary structure prediction is evaluated by performing Monte Carlo simulated annealing on test protein sequences. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Neural network‐based prediction of mutation‐induced protein stability changes in Staphylococcal nuclease at 20 residue positions
Authors: Frenz Christopher M.
Published: February 2005

Protein‐based therapeutics are playing an increasingly important role in the treatment of diseases, including diabetes and cancer. The viability of these treatments, however, are highly dependent on the stability of the therapeutic, since stability affects both the shelf life of the therapeutic as well as its active life in the body. Stability engineering can, therefore, be used to increase the effectiveness of protein‐based therapeutics. Computational methods of protein stability prediction have been under development for about a decade, but complex molecular interactions make stability prediction difficult and computationally intensive. A rapid computational method of protein stability prediction is developed using feed‐forward neural networks and used to predict mutation‐induced stability changes in Staphylococcal nuclease. The input to the neural network consisted of sequences of evolutionarily based amino acid similarity scores that were obtained through the comparison of the amino acids in a mutation containing sequence to their positional counterparts in the baseline wild‐type amino acid sequence. A training set was created which consisted of similarity score sequences, for which the stabilities of the corresponding amino acid sequences were known, paired with the relative stabilities of the sequences to that of the baseline. Back‐propagation of error was used to train the network to output accurate relative stability scores for the sequences in the training set. Neural network‐based relative stability predictions for 55 sequences containing mutation combinations not found in the training set had an accuracy of 92.8%. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Characterization of differently grown GaN epilayers by time‐resolved four‐wave mixing technique
Authors: Jarašiūnas K. , Malinauskas T. , Aleksiejūnas R. , Sūdžius M. , Frayssinet E. , Beaumont B. , Faurie J.‐P. , Gibart P.
Published: February 2005

Room temperature time‐resolved four‐wave mixing has been performed in MOCVD GaN epilayers, grown on sapphire substrates by using either conventional or a 3D‐growth mode with Si/N treatment technique (micro‐ELO). Picosecond pulses at 355 nm were used to create light interference pattern and record a spatially modulated carrier distribution by interband transitions, while a delayed probe beam at 1064 nm monitored the carrier dynamics far from the bandgap. The determined values of the bipolar diffusion coefficient and the carrier lifetime were found equal to Da = 1.7–1.8 cm2/s and τR ≈ 1.1 ns for standard grown epilayers, while in the samples with ultralow dislocation density they were found equal to 2.4 cm2/s and 2.7 ns. In the interface region of the epilayers with high dislocation density, a dependence of D and τR values on excitation intensity was found. The latter effect was attributed to a screening of potencial barriers around the charged dislocations by free carriers and an ability of the carriers to become less localized and thus avoid the nonradiative recombination at dislocations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Free energy and capture cross section of the E2 trap in n‐type GaN
Authors: Pernot J. , Ulzhöfer C. , Muret P. , Beaumont B. , Gibart P.
Published: February 2005

Free energy and capture cross section of the E2 trap in n‐type GaN are investigated by deep level transient spectroscopy with the help of an experimental method, relying on space charge depth modulation [D. Pons, J. Appl. Phys. 55, 3644 (1984)]. This technique is applied with a large range of filling pulse durations (up to 6 orders of magnitude) and for temperature varying between 260 K and 330 K. Entropy and capture barrier are found to be negligible. Analysis of our results makes N in Ga site (NGa antisite) as the best candidate for this trap. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect tuning of GaAs doping superlattices by hydrogen ion implantation
Authors: Brink D. J. , Haile K. M. , Kunert H. W.
Published: February 2005

GaAs doping superlattices were implanted with 0.5 MeV hydrogen ions at doses ranging from 1012 to 1016 cm–2. This gradually modified their optical characteristics from superlattice behaviour to something resembling the bulk material and beyond. Ellipsometry and near infrared reflectance measurements were used to determine the dose dependent effective band gap. Implantation damage could be reversed to a large extent by a simple thermal annealing step. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Terahertz generation by plasma waves in nanometer gate high electron mobility transistors
Authors: Łusakowski J. , Teppe F. , Dyakonova N. , Meziani Y. M. , Knap W. , Parenty T. , Bollaert S. , Cappy A. , Popov V. , Shur M. S.
Published: February 2005

A resonant voltage tuneable radiation (0.4 THz–1.0 THz) from the gated two dimensional electron gas in a 60 nm InGaAs field effect transistor was investigated. We show that (i) the observed emission appears once the drain‐to‐source voltage, UDS, exceeds the threshold value, UTH; (ii) the resonant frequency can be tuned by UDS in agreement with the current driven plasma instability model of Dyakonov and Shur; (iii) by applying a quantizing magnetic field one increases UTH linearly with the magnetic field while the evolution of the emission signal is approximately a universal function of (UDS–UTH). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Barrier inhomogeneities and electrical characteristics of Ni/Ti bilayer Schottky contacts on 4H–SiC after high temperature treatments
Authors: Pérez R. , Mestres N. , Montserrat J. , Tournier D. , Godignon P.
Published: February 2005

The analysis of “nonideal” behaviour in current–voltage characteristics of fabricated Schottky diodes on 4H–SiC is carried out. An accurate theoretical modelling of the effect of the presence of inhomogeneities on the electron transport across the metal‐semiconductor interface is applied. This model trends to explain a large series of abnormal experimental results obtained on “real” Schottky diodes. Our results clearly demonstrate that the electron transport at the metal–semiconductor interface is significantly affected by low barrier regions. It is suggested that the commonly observed larger‐than‐unity ideality factors, underestimation of the Richardson constant and Schottky Barrier Height correlation with ideality factor can be attributed to an effective area involved in the current transport which may be significantly lower than the geometric area of the diode contact. It is also proved by comparing different types of Schottky diodes that in order to properly characterise the interface uniformity, not only the absolute value of the ideality factor is important but also its temperature dependence and its correlation with barrier height have to be taken into account. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Manifestation of the equilibrium hole distribution in photoluminescence of n‐InN
Authors: Klochikhin A. A. , Davydov V. Yu. , Emtsev V. V. , Sakharov A. V. , Kapitonov V. A. , Andreev B. A. , Lu Hai , Schaff William J.
Published: February 2005

Photoluminescence (PL) of n‐InN grown by molecular beam epitaxy with Hall concentrations from 3.6 to 7.3 × 1017 cm–3 demonstrates dependences on carrier concentration, temperature, and excitation density which give evidences of a fast energy relaxation rate of photoholes and their equilibrium distribution over localized states. The structure of the PL spectra observed at 4.2 and 77 K in the energy interval from 0.50 to 0.67 eV indicates that a considerable part of holes is trapped by deep and shallow acceptors before the interband recombi‐ nation with degenerate electrons occurs. At room temperature, the band‐to‐band recombination of free holes and electrons dominates in PL. Experimental results on PL and absorption are described by model calculations under the assumptions of a band gap equal to 0.665–0.670 eV at zero temperature and zero carrier concentration and a non‐parabolic conduction band with the effective mass at the G‐point equal to 0.07 of the free electron mass. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Liquid chromatography/mass spectrometry analysis of bifunctional electrophiles and DNA adducts from vitamin C mediated decomposition of 15‐hydroperoxyeicosatetraenoic acid
Authors: Williams Michelle V. , Lee Seon Hwa , Blair Ian A.
Published: February 2005

Reactive oxygen species convert the ω‐6 polyunsaturated fatty acid arachidonic acid into 15‐hydroperoxy‐5,8,11,13‐(Z,Z,ZE)‐eicosatetraenoic acid (15‐HPETE). Cyclooxygenases and lipoxygenases can also convert arachidonic acid into 15‐HPETE. Vitamin C mediated decomposition of 15(S)‐HPETE to protein‐ and DNA‐reactive bifunctional electrophiles was examined by normal‐phase liquid chromatography/atmospheric pressure chemical ionization/mass spectrometry (LC/APCI‐MS). The individual bifunctional electrophiles, trans‐4,5‐epoxy‐2(E)‐decenal (t‐EDE), cis‐4,5‐epoxy‐2(E)‐decenal (c‐EDE), 4‐oxo‐2(E)‐nonenal (ONE), and 4‐hydroxy‐2(E)‐nonenal (HNE), exhibited protonated molecules at m/z 169, 169, 155, and 157, respectively. The MH+ ion at m/z 173 for 4‐hydroperoxy‐2(E)‐nonenal (HPNE) was very weak with an ion corresponding to the loss of OH at m/z 156 as the major ion in the APCI mass spectrum. The bifunctional electrophiles were all separated under normal‐phase LC conditions. All five bifunctional electrophiles were formed when 15‐HPETE was treated with vitamin C. The LC/MS‐based methodology showed that t‐EDE was the major bifunctional electrophile formed during vitamin C mediated 15(S)‐HPETE decomposition. Stable isotope dilution LC/MS studies revealed that this did not result in the formation of increased levels of unsubstituted etheno‐dGuo adducts in calf thymus DNA when compared with 13(S)‐hydroperoxy‐9,10‐(Z,E)‐octadecadienoic acid [13(S)‐HPODE], a lipid hydroperoxide derived from linoleic acid. However, the formation of heptanone‐etheno‐dGuo adducts in calf thymus DNA was reduced when compared with the 13(S)‐HPODE. This was attributed to the reduced formation of ONE from 15‐HPETE when compared with its formation from 13‐HPODE. In contrast to reactions with dGuo or DNA conducted using 13(S)‐HPODE, no carboxy‐containing adducts were observed with 15(S)‐HPETE. Copyright © 2005 John Wiley & Sons, Ltd.
An accurate semi‐empirical equation for sputtering yields I: for argon ions
Authors: Seah M. P. , Clifford C. A. , Green F. M. , Gilmore I. S.
Published: February 2005

An analysis has been made of the historical data for argon ion sputtering yields of 28 mono‐elemental solids in the energy range 250–10 000 eV to develop an improved semi‐empirical formula based on Matsunami et al.'s and Yamamura and Tawara's formulations. The best result is found if an essential component involving the target density is included in Matsunami et al.'s approach. The scatter between the predictions and the experimental data is reduced to 9.0% by generating an analytical expression for the term Q that requires none of the target‐specific numbers from special look‐up tables of the type used by Matsunami et al. and Yamamura and Tawara. For elements other than the 34 elements for which Q values are tabulated, the new Q values range up to a factor of 5 from the default value that they recommend.

The predictions are tested by a new method for determining sputtering yields using atomic force microscopy to measure very small crater volumes sputtered in ultrahigh vacuum. Here, 26 mono‐elemental targets were studied using a 5 keV argon ion beam set at 45° to the surface normal. The effect of the angle of incidence is evaluated best using Yamamura et al.'s angular equations for this contribution. Results for Sb, Te and Bi indicate a significantly higher sputtering yield than expected. This is thought to arise from the high content of polyatomic groups associated with the low sublimation energies for such clusters in the pure elements of groups V‐B and VI‐B of the Periodic Table. These 5 keV sputtering yield data, excluding Sb, Te and Bi, fit the new equations with a scatter of 20%. Results using SRIM‐2003 exhibit a poorer scatter of 27%. © Crown Copyright 2005. Reproduced with the permission of Her Majesty's Stationary Office. Published by John Wiley & Sons, Ltd.
Chemotaxis of the unicellular green algaDunaliella salinaand the ciliatedTetrahymena pyriformis—effects of glycine, lysine, and alanine, and their oligopeptides
Authors: Köhidai L. , Kovács P. , Csaba G.
Published: February 2005

Chemotactic properties of amino acids (L-alanine, glycine and L-lysine) and their oligopeptides (10−6M) and binding sites to these ligands were investigated in two unicellular models, the heterotrophic Tetrahymena pyriformis and the auxotrophic Dunaliella salina. Chemotaxis of Dunaliella induced by simple amino acids and their derivatives demonstrated that binding sites (receptors) for food molecules are not only present in the membrane but are also able to induce their basic physiological response. In Tetrahymena, substances with special molecular structure and properties (polar, hydrophilic character of the signal peptide chain)-5-L-Lys, 5-Glywere required for chemoattraction, other peptides tested, lacking the required structure, were repellent. Divergences in chemotaxis and binding assays of both species suggest that trends of functional and binding parameters do not run parallel at this level of evolution.
The effect of collagenase and temperature on mitochondrial respiratory parameters in saponin-skinned cardiac fibers
Authors: Toleikis Adolfas , Majiene Daiva , Trumbeckaite Sonata , Dagys Arvydas , Jasaitis Antanas
Published: February 2005

The results of a comparative study of the respiration rates of mitochondria in saponin-skinned rat cardiac fibers (SF) and in fibers treated with saponin and collagenase (SCF) suggest that only about half of the whole population of mitochondria manifest their activity in SF, in contrast to SCF, in response to extracellular substrates of oxidative phosphorylation. The apparent Km value for ADP with succinate as substrate, which was as high as 330±32 μM in SF in SF at 20 °C, decreased about 2-fold in SCF at the same temperature and in SF at 37 °C, and decreased further to 67±8 μM in SCF at 37 °C. Thus, weakening or breaking of cellular contacts by collagenase and the temperature-dependence of diffusion of substrates such as ADP, seem to be important factors that determine the respiratory activity and regulatory parameters of mitochondria in saponin-permeabilized cardiomyocytes.
Fluorescence study on transmembrane Ca2+ gradient-mediated conformation changes of sarcoplasmic reticulum Ca2+-ATPase
Authors: Tu Y. P. , Yang F. Y.
Published: February 2005

The conformational states of Ca2+-ATPase in sarcoplasmic reticulum (SR) vesicles with or without a thousand-fold transmembrane Ca2+ gradient have been studied by fluorescence spectroscopy and fluorescence quenching. In consequence of the establishment of the transmembrane Ca2+ gradient, the steady-state fluorescence results revealed a reproducible 8% decrease in the intrinsic fluorescence while time-resolved fluorescence measurements showed that 13 tryptophan residues in SR · Ca2+-ATPase could be divided into three groups. The fluorescence lifetime of one of these groups increased from 5.5 ns to 5.95 ns in the presence of a Ca2+ gradient. Using KI and hypocrellin B (a photosensitive pigment obtained from a parasitic fungus, growing in Yunnan, China), the fluorescence quenching further indicated that the dynamic change of this tryptophan group, located at the protein-lipid interface, is a characteristic of transmembrane Ca2+ gradient-mediated conformational changes in SR · Ca2+-ATPase.
Carrier-mediated lactate entry into isolated hepatocytes from fed and starved rats: Zonal distribution and temperature dependence
Authors: Staricoff M. A. , Cohen R. D. , Monson J. P.
Published: February 2005

We examined the possibility of quantitative differences in lactate entry into periportal and perivenous hepatocytes under different nutritional states. The rate of14C-L(+)-lactate uptake was determined after 15-second incubations with freshly isolated zonally separated hepatocytes using a centrifuge stop technique at 37 °C and 4 °C, in the presence or absence of either differing amounts of unlabelled lactate or of a hepatocyte lactate transport inhibitor,α-cyano-3-hydroxycinnamate. Total entry as well as carrier mediated entry of14C-L(+)-lactate into the isolated cell populations was found to be similar in periportal and perivenous hepatocytes, irrespective of the nutritional state of the animal. Periportal and perivenous hepatocytes showed a greater tendency to transport lactate when isolated from starved animals, in agreement with previously reported data from non-zonally separated isolated hepatocytes. The activity of the hepatocyte plasma-membrane lactate transporter was diminished between fourfold and eightfold in transport studies conducted at 4 °C; similar results were obtained in unseparated and zonally separated suspensions. Temperature dependence of the hepatocyte transporter is markedly less than that reported for the erythrocyte transporter.
Myelopeptides: Bone marrow regulatory mediators
Authors: Petrov Rem V. , Mikhailova Augusta A. , Fonina Larissa A.
Published: February 2005

Bone marrow cells of various animal species and men produce a group of bioregulatory peptides called myelopeptides (MPs). A highly purified MP fraction and some individual molecules have been isolated from the supernatant of porcine bone marrow cell cultures by reverse phase chromatography.

MPs have a wide spectrum of functional activities: immunoregulatory, differentiating and opiate-like. They evoke 2–5-fold stimulation of antibody production to various antigens. They correct some immune defects in MRL/lpr mice with spontaneous autoimmune disorders that results in 2-fold prolongation of the life span of these mice. MPs influence the differentiation of bone marrow and peripheral blood cells derived from healthy and leukemic donors. They induce terminal differentiation in the leukemic human HL-60 cell line. MPs also show an effect on pain sensitivity.

A new immunocorrective drug Myelopid has been developed on the basis of MP mixtures. This drug is effectively used in Russia both in medicine and veterinary practice for prophylaxis and treatment of diseases accompanied by immunodeficiency.

Two individual MPs were isolated and identified: Phe-Leu-Gly-Phe-Pro-Thr (MP-1) and Leu-Val-Val-Tyr-Pro-Trp (MP-2). MP-1 displays immunoregulatory activity; MP-2 abolishes the inhibitory effect of leukemic cells on T-lymphocyte functional activity.

MPs seem to provide not only immunoregulation but also to participate in complex interactions between different systems in the organism.
Effect of streptozotocin diabetes on polysomal aggregation and protein synthesis rate in the liver of pregnant rats and their offspring
Authors: Martin M. E. , Garcia A. M. , Blanco L. , Herrera E. , Salinas M.
Published: February 2005

To study the effect of diabetes on hepatic protein synthesis and polysomal aggregation in pregnant rats, female rats were treated with streptozotocin prior to conception. Some animals were mated, and studied at day 20 of pregnancy, whereas, others were studied in parallel under non pregnant conditions. The protein synthesis rate measured with an “in vitro” cell-free system was higher in pregnant than in virgin control rats. It decreased with diabetes in both groups, although values remained higher in diabetic pregnant rats than in the virgin animals. The fetuses of diabetic rats had a lower protein synthesis rate than those from controls, although they showed a higher protein synthesis rate than either their respective mothers or virgin rats. Liver RNA concentration was higher in control and diabetic, pregnant rats than in virgin rats, and the effect of diabetes decreasing this parameter was only significant for pregnant rats. Liver RNA concentration in fetuses was lower than in their mothers, and did not differ between control and diabetic animals. The decreased protein synthesis found in diabetic animals was accompanied by disaggregation of heavy polysomes into lighter species, indicating an impairment in peptide-chain initiation.
Endosomes, receptor tyrosine kinase internalization and signal transduction
Authors: Bergeron John J. M. , Di Guglielmo G. M. , Baass Patricia C. , Authier François , Posner Barry I.
Published: February 2005

Upon the binding of insulin or epidermal growth factor to their cognate receptors on the liver parenchymal plasmalemma, signal transduction and receptor internalization are near co-incident. Indeed, the rapidity and extent; of ligand mediated receptor internalization into endosomes in liver as well as other organs predicts that signal transduction is regulated at this intracellular locus. Although internalization has been thought as a mechanism to attenuate ligand mediated signal transduction responses, detailed studies of internalized receptors in isolated liver endosomes suggest an alternative scenario whereby selective signal transduction pathways can be accessed at this locus.
Control of glucose transport by GLUT1: Regulated secretion in an unexpected environment
Authors: Widnell Christopher C.
Published: February 2005

Studies designed to elucidate the mechanism of regulation of the GLUT1 isoform of the glucose transporter in response to a variety of cellular stresses are reviewed. Using ts mutants of vesicular stomatitis virus, it was shown that the viral L gene was responsible for the stimulation of glucose transport in infected cells. Immunofluorescence of GLUT1 demonstrated that the increase in glucose transport was the consequence of a translocation of the transporter from a reservoir in cytoplasmic vesicles to the plasma membrane. When cells were cycled between deficient and standard medium, the change in glucose transport rates was paralleled by a cycling of the transporter between the plasma membrane and the cytoplasmic vesicles. The redistribution of GLUT1 was not a consequence of a general redistribution of recycling plasma membrane proteins. Instead, the findings focus attention on the regulated exocytosis of specific membrane constituents in cells that, until recently, were not thought to exhibit this capacity.
Novel leukaemia markers
Authors: Micklem Kingsley J.
Published: February 2005

Using synthetic peptide or recombinant protein as immunising antigens we have produced monoclonal antibodies and polyclonal antisera directed against targets of particular interest in leukaemia diagnosis. In this way we have prepared reagents which recognise all T or all B lymphocytes in routinely fixed paraffin sections which are unique in this respect. We have also produced monoclonal antibodies to molecules potentially involved in specific neoplastic transformations, implicated by virtue of the involvement of their genes in chromosomal defects in these neoplasms. In particular, we have produced antibodies recognising bcl-2, involved in follicular lymphoma, tal-1, involved in T-cell acute leukaemias and HRX involved in a variety of hematologic disorders. The application of these reagents to diagnosis has so far proved useful. In addition their use outside the field of leukaemia diagnosis has proved to be even more important in some cases.
Immune receptor repertoire for influenza haemagglutinin
Authors: Thomas D. Brian , Patera Andriani , Graham Christine M. , Smith Claire A.
Published: February 2005

An extensive analysis was made of receptor specificity and gene usage in the neutralising antibody (mAb) and Class II-restricted T cell responses to influenza haemagglutinin (HA) following natural infection of MHC (H-2k or H-2d) congenic mice with X31 virus (H3N2 subtype). Despite the diversity of available antigenic sites on the HA1 subunit, there was striking immunodominance in the mAb response as deduced by sequencing the HA genes of escape mutants and the corresponding antibody H and L chain gene rearrangements. Similarly, Class II restricted T cell responses of individual donors focused on a single antigenic site, or immunodominant peptide; and PCR sequence analysis of T cell receptor (αβ) gene usage indicated that T cell memory was derived from a single progenitor cell. Focusing of the immune repertoire to limited regions of the HA molecule during a primary viral infection may be a significant factor in immune pressure for antigenic variation.
Watching small molecules move: Interrogating ionic channels using neutral solutes
Authors: Parsegian V. A. , Bezrukov S. M. , Vodyanoy I.
Published: February 2005

Whether they are small enough to wriggle through the current-carrying part of an ionic channel or big enough to be kept outside and thus able to exert an osmotic stress on the channel space, polymers interact with channels in several instructive ways. The osmotic stress of excluded polymers allows one to measure the number of water molecules that come out of the channel in transitions between various “open” to “closed” states. The loss of osmotic activity, due to the partial or completely unrestricted admission of small polymers becomes a measure of the transfer probabilities of polymers from solution to small cavities; it provides an opportunity to study polymer conformation in a perfectly sieved preparation. Current fluctuations due to the partial blockage by a transient polymer are converted into estimates of times of passage and diffusion constants of polymers in channels. These estimates show how a channel whose functional states last for milliseconds is able to average over the interactions with polymers, interactions that last only microseconds. One sees clearly that in this averaging, the macromolecular channel is large enough to react like a macroscopic object to the chemical potentials of the species that modulate its activity.
Transformations of normal and inverted function tables
Authors: Zucker J. I.
Published: February 2005

We develop a theory of function tables, similar to, and inspired by, that given in the work of D. Parnas. We consider, in particular, two classes of function tables: normal and inverted. We study effective transformations between tables of these two classes, as well as transformations which change the dimension of a table. We also consider the interrelationship between these three types of transformation.
Specification and correctness proof of a WAM extension with abstract type constraints
Authors: Beierle Christoph , Börger Egon
Published: February 2005

We provide a mathematical specification of an extension of Warren's Abstract Machine (WAM) for executing Prolog to type-constraint logic programming and prove its correctness. Our aim is to provide a full specification and correctness proof of a concrete system, the PROTOS Abstract Machine (PAM), an extension of the WAM by polymorphic order-sorted unification as required by the logic programming language PROTOS-L.

In this paper, while leaving the details of the PAM's type constraint representation and solving facilities to a sequel to this work, we keep the notion of types and dynamic type constraints abstract to allow applications to different constraint formalisms like Prolog III or CLP(R). This generality permits us to introduce modular extensions of Börger's and Rosenzweig's formal derivation of the WAM. Since the type constraint handling is orthogonal to the compilation of predicates and clauses, we start from type-constraint Prolog algebras with compiled AND/OR structure that are derived from Börger's and Rosenzweig's corresponding compiled standard Prolog algebras. The specification of the type-constraint WAM extension is then given by a sequence of evolving algebras, each representing a refinement level, and for each refinement step a correctness proof is given. Thus, we obtain the theorem that for every such abstract type-constraint logic programming system L, every compiler to the WAM extension with an abstract notion of types which satisfies the specified conditions, is correct.
A tactic calculus — abridged version
Authors: Martin A. P. , Gardiner P. H. B. , Woodcock J. C. P.
Published: February 2005

We present a very general language for expressing tactic programs. The paper describes some essential tactic combinators (tacticals), and gives them a formal semantics. Those definitions are used to produce a complete calculus for reasoning about tactics written in this language. The language is extended to cover
structural combinators
which enable the tactics to be precisely targeted upon particular sub-expressions.
Involvement of CD14 in the inhibitory effects of dimethyl‐α‐cyclodextrin on lipopolysaccharide signaling in macrophages
Authors: Motoyama Keiichi , Arima Hidetoshi , Nishimoto Yoji , Miyake Kensuke , Hirayama Fumitoshi , Uekama Kaneto
Published: February 2005

The potential use of α‐cyclodextrin and its hydrophilic α‐cyclodextrin derivatives (α‐CyDs) as antagonists against lipopolysaccharide (LPS), which stimulates the nitric oxide (NO) and tumor necrosis factor‐α (TNF‐α) production as well as nuclear factor‐κB (NF‐κB) activation in macrophages was examined. Of three α‐CyDs used in the present study, 2,6‐di‐O‐methyl‐α‐CyD (DM‐α‐CyD) had greater inhibitory activity than did the other CyDs against NO and TNF‐α production through an impairment of gene expression in macrophage cell lines and primary macrophages stimulated with LPS and lipid A in a concentration‐dependent manner. Concomitantly, DM‐α‐CyD inhibited NF‐κB translocation into nucleus. These inhibitory effects of DM‐α‐CyD could be attributed to the release of CD14 from lipid rafts caused by an efflux of phospholipids, but not cholesterol. These results suggest that DM‐α‐CyD may have promise as a potent and unique antagonist for excess activation of macrophages stimulated with LPS.
Influence of hydrophobic matching on association of model transmembrane fragments containing a minimised glycophorin A dimerisation motif
Authors: Orzáez Mar , Lukovic Dunja , Abad Concepción , Pérez-Payá Enrique , Mingarro Ismael
Published: February 2005

The principles that govern the folding and packing of membrane proteins are still not completely understood. In the present work, we have revisited the glycophorin A (GpA) dimerisation motif that mediates transmembrane (TM) helix association, one of the best‐suited models of membrane protein oligomerisation. By using artificial polyleucine TM segments we have demonstrated in this study that a pattern of only five amino acids (GVxxGVxxT) promotes specific dimerisation. Further, we have used this minimised GpA motif to assess the influence of hydrophobic matching on the TM helix packing process in detergent micelles and found that this factor modulates helix–helix association and/or dissociation between TM fragments.