bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluating the amino acid CF3‐bicyclopentylglycine as a new label for solid‐state 19F‐NMR structure analysis of membrane‐bound peptides
Authors: Afonin Sergii , Mikhailiuk Pavel K. , Komarov Igor V. , Ulrich Anne S. 
Published: August 2007

AbstractThe conformation, alignment and dynamic behavior of membrane‐bound peptides is readily accessible by solid‐state 19F‐NMR spectroscopy, but it has been difficult to incorporate suitable 19F‐labelled amino acids into synthetic peptides. To avoid the drawbacks of previously used labels, we have rationally designed and synthesized a novel amino acid that suits all theoretical and practical requirements for peptide synthesis and subsequent 19F‐NMR structure analysis [Mikhailiuk et. al, Angew. Chem. 2006, 118, 5787–5789]. The enantiomerically pure L‐form of 3‐(trifluoromethyl)bicyclopent‐[1.1.1]‐1‐ylglycine (CF3‐Bpg) carries a CF3 group that is rigidly attached to the peptide backbone and does not racemize during peptide synthesis. It could be demonstrated for several different peptides that their biological activity is usually not affected by a single label, nor the conformation, as monitored by circular dichroism. Here, we carry out a more detailed structure analysis to evaluate the potential and reliability of CF3‐Bpg for solid‐state NMR, using the well‐known α‐helical antimicrobial peptide PGLa as a test case. We have collected several orientational constraints from the anisotropic 19F19F dipolar couplings of CF3‐Bpg in various positions of PGLa embedded in lipid bilayers. These resulting structural parameters are then compared with those previously determined from 4‐CF3‐phenylglycine and 3,3,3‐d3‐alanine labels on the same peptide. The analysis confirms that CF3‐Bpg does not perturb the α‐helical conformation of PGLa. Likewise, the helix alignment is shown to follow the established concentration‐dependent pattern in realigning from a surface‐bound S‐state to an obliquely tilted T‐state. Hence, the advantages of CF3‐Bpg over all previously used 19F‐labeled side chains are evident, as they combine ease of chemical incorporation and peptide purification with high NMR sensitivity and absent background signals, allowing a straightforward analysis of the dipolar splittings with no need for chemical shift referencing without any ambiguity in the sign of the couplings. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Design of a positron microprobe using magnetic lenses
Authors: Maekawa M. , Yu R. S. , Kawasuso A. 
Published: August 2007

AbstractWe have designed a positron microbeam using magnetic lenses based on the commercial scanning electron microscope (SEM). Employing a source with a diameter of 1 mm and an immersion lenses, the diameter of primary beam can be reduced to 200 μm. This could be further reduced to less than 10 μm using the SEM optics. By introducing a beam pulsing section, positron lifetime measurement using a pulse beam will be also enabled. The extraction of positron beam from the magnetic field was simulated numerically. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of a Na‐22 based pulsed slow positron beam for depth‐selective PALS
Authors: Ohdaira T. , Muramatsu M. , Suzuki R. , Kobayashi Y. , Takanawa M. , Hashimoto N. , Takao K. , Kobayashi Y. 
Published: August 2007

AbstractWe developed a Na‐22 based pulsed slow positron beam system for depth‐selective positron‐annihilation lifetime spectroscopy. The use of high‐efficiency moderator and high‐compression beam bunchers enable practical measurements with using a relatively low activity positron source. An initial performance test showed timing resolution less than 250 ps and count rate of 1k counts/s with use of 0.5 GBq Na‐22. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Implementation of the Munich scanning positron microscope at the positron source NEPOMUC
Authors: Piochacz C. , Egger W. , Hugenschmidt C. , Kögel G. , Schreckenbach K. , Sperr P. , Dollinger G. 
Published: August 2007

AbstractThe Munich scanning positron microscope (Spm) permits positron lifetime measurements with a lateral resolution down to 2 µm within an energy range of 1‐20 keV. One practical limitation of the Spm is set by the long measurement times of several days per a 2D‐scan due to the low intensity positron beam produced by standard 22Na sources. This disadvantage will be overcome by installing the Spm at the high intense positron beam facility Nepomuc at the research reactor FRM II in Garching. Thus the time for one measurement will be shortened by a factor of 60. In addition it is expected to reduce the lateral resolution to about 100 nm. Due to the beam characteristics of the Nepomuc facility an interface is needed, which enhances the phase space density of the beam. The requirements, which have to be fulfilled by the interface, will be described and an overview of the different components such as bunching units, remoderation stages and rf‐elevator will be given. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Age‐hardening in a commercial Mg‐based alloy
Authors: Macchi C. E. , Somoza A. , Nie J. F. 
Published: August 2007

AbstractAge‐hardening phenomena induced by thermal and thermo‐mechanical treatments in the commercial Mg‐based alloy WE54 were studied by positron annihilation lifetime spectroscopy and Vickers microhardness. To this aim, samples were plastically deformed and subsequently aged at 250 °C for times ranging from 0 to 1000 hours. The results obtained are discussed in terms of the role of vacancies in the solute transport and therefore they contribute to the discussion on the vacancy‐solute clusters (and/or intermediate precipitates) interactions during the precipitation sequence of the WE54. Besides, we show that cold work previous aging not only accelerates but increases the hardening response of the alloy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Detection of formation and annihilation process of point defects produced by three deformation modes using Cu precipitation behavior in Fe‐Cu alloy
Authors: Sato Koichi , Kai Mototaka , Mitoma Kotaro , Xu Qiu , Yoshiie Toshimasa 
Published: August 2007

AbstractSpecimens of pure Fe, Fe‐0.15wt.%Cu and Fe‐0.6wt.%Cu were deformed with 10% strain by three deformation modes (rolling, compression and tension), and were measured using positron annihilation spectroscopy after annealing from 373 K to 873 K per 100 K for 1 hour. The positron annihilation lifetime of vacancies after deformation was about 135 psec, and most of the vacancies produced by deformation were expected to be trapped at the dislocation core, and were released from it at 573 K. In Fe‐0.15%Cu, Cu precipitates were not produced, and the formation and annihilation behavior of vacancies was similar to pure Fe. In each deformation, cell structures were different, so, in the Fe‐0.6%Cu, growth of Cu precipitates was different. The tension, rolling and compression were ranked in a descending order of degree of contribution of the vacancies released from the dislocations to the growth of Cu precipitation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluation of radiation stability of Generation IV structural materials by positron annihilation spectroscopy
Authors: Zeman Andrej , Debarberis Luigi , Kočík Jan , Slugeň Vladimír 
Published: August 2007

AbstractThe issue concerning the structural integrity of materials is still playing a dominant role due to the degradation mechanisms, such as hardening, phase instability and embrittlement, which must be understood in order to estimate the component lifetime. In this paper we present some interesting results on few structural materials pre‐selected for Generation IV reactor concepts. The study is based on the application of non‐destructive spectroscopic techniques, in particular positron annihilation spectroscopy combined with transmission electron microscopy to investigate advanced steels, as P91, T91 and. Analysis of experimental results confirmed that P91 has indicated lower radiation stability than T91 and EUROFER 97 respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron characterization of metastable phases in yttria stabilized zirconia
Authors: Damonte L. C. , Caracoche M. C. , Lamas D. 
Published: August 2007

AbstractThe thermal evolution of positron annihilation parameters in nanosized 10 mol% Y2O3 doped ZrO2 powders is presented. Three positron lifetimes have been determined up to 900 °C annealing temperature. The two major ones have been interpreted, one as a mean between positron annihilation in the bulk and in vacancy‐like open volume defects and the other, as due to annihilation in higher sized volume defects. The intensity ratio between the two defect structures depends on temperature and could be reflecting the thermal t″‐ to cubic metastable transformation known to occur in the studied system. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exactly solvable Schrödinger equations with a position‐dependent mass: Null potential
Authors: Peña J. J. , Ovando G. , Morales J. , García‐Ravelo J. , Pacheco‐García C. 
Published: August 2007

AbstractIn this work, an alternative approach for finding exact solutions of Schrödinger equations with a position‐dependent mass is presented. Essentially, the method consists in transforming the position‐dependent mass Schrödinger equation into a standard constant mass Schrödinger equation. The constant mass equation is formulated in terms of a new variable and includes, as effective potential, a term related to the position‐dependent mass and another term connected with the original potential. For exactly solvable potentials, our proposal leads to a Riccati equation for an equivalent Witten superpotential, which means that this kind of problems can be studied within the quantum supersymmetric framework with the aim to find the explicit solutions and the energy spectra. To show the usefulness of the proposed approach, we consider the particular case of exactly solvable Schrödinger equations for different position‐dependent mass situations in a null potential. However, the method can directly be applied to other effective potentials as well as to find isospectral potentials for specific position‐dependent mass distributions. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Study of the phase I and phase II metabolism of a mixture containing multiple tanshinones using liquid chromatography/tandem mass spectrometry
Authors: Liu Jie , Wu Jianlin , Wang Xiaoru , Cai Zongwei 
Published: August 2007

AbstractMetabolism of a mixture containing four dominant components in lipid solubles of Danshen was studied both in vitro and in vivo. The parent compounds and their metabolites were simultaneously detected by using liquid chromatography coupled with ion trap mass spectrometry. The results indicated that oxidation was the major pathway in phase I metabolism. O‐Glucuronidation of the hydroxylated tanshinones was identified in the rat urine samples collected after the oral administration of the tanshinone components. The metabolic rates obtained from the in vitro metabolism study of each individual component were significantly different from those obtained from the incubation study of the four components in a cassette. Metabolite identification showed that tanshinone IIA and tanshinone I were the major metabolites of cryptotanshinone and dihydrotanshinone I, respectively. The obtained results demonstrated the metabolic change between the active components in Danshen and suggested the need to study the multiple components or even the extract from the herbal medicines. Copyright © 2007 John Wiley & Sons, Ltd.
A predictive control strategy for norm‐bounded LPV discrete‐time systems with bounded rates of parameter change
Authors: Casavola Alessandro , Famularo Domenico , Franzè Giuseppe 
Published: August 2007

AbstractA novel predictive control strategy for input‐saturated norm‐bounded linear parameter varying discrete‐time systems is proposed. The solution is computed by minimizing an upper bound to the ‘worst‐case’ infinite horizon quadratic cost under the constraint of steering the future state evolutions, emanating from the current state, into a feasible and positive invariant set. It will be shown that the ‘size’ of this terminal set depends on the rate of change of the scheduling parameter, which is assumed to be bounded and measurable. Copyright © 2007 John Wiley & Sons, Ltd.
Limit theory for the random on‐line nearest‐neighbor graph
Authors: Penrose Mathew D. , Wade Andrew R. 
Published: August 2007

AbstractIn the on‐line nearest‐neighbor graph (ONG), each point after the first in a sequence of points in ℝdis joined by an edge to its nearest neighbor amongst those points that precede it in the sequence. We study the large‐sample asymptotic behavior of the total power‐weighted length of the ONG on uniform random points in (0,1)d. In particular, ford= 1 and weight exponentα> 1/2, the limiting distribution of the centered total weight is characterized by a distributional fixed‐point equation. As an ancillary result, we give exact expressions for the expectation and variance of the standard nearest‐neighbor (directed) graph on uniform random points in the unit interval. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Smooth bootstrap methods for analysis of longitudinal data
Authors: Li Yue , Wang You‐Gan 
Published: August 2007

AbstractIn analysis of longitudinal data, the variance matrix of the parameter estimates is usually estimated by the ‘sandwich’ method, in which the variance for each subject is estimated by its residual products. We propose smooth bootstrap methods by perturbing the estimating functions to obtain ‘bootstrapped’ realizations of the parameter estimates for statistical inference. Our extensive simulation studies indicate that the variance estimators by our proposed methods can not only correct the bias of the sandwich estimator but also improve the confidence interval coverage. We applied the proposed method to a data set from a clinical trial of antibiotics for leprosy. Copyright © 2007 John Wiley & Sons, Ltd.
Responding for brain stimulation reward in the bed nucleus of the stria terminalis in alcohol‐preferring rats following alcohol and amphetamine pretreatments
Authors: Eiler William J.A. , Hardy Lathen , Goergen Josuha , Seyoum Regat , Mensah‐Zoe Boikai , June Harry L. 
Published: August 2007

AbstractThe bed nucleus of the stria terminalis (BNST) has been reported to release increased levels of extracellular dopamine (DA) following the systemic administration of abused drugs in outbred rats. This study examined the BNST as a novel locus for supporting operant responding for brain stimulation reward (BSR) in rats bred for alcohol preference while determining any potentiating effects of ethanol (EtOH) (0.125–1.25 g/kg, i.p.) and amphetamine (0.25–1.60 mg/kg, i.p.) on BSR within the BNST. Also examined was the capability of D1 receptor blockade to attenuate any observed potentiation. Following surgical implantation, alcohol‐preferring (P) and nonpreferring (NP) rats responded to a range of descending frequencies (300–20 Hz) as evaluated by a rate‐frequency paradigm. The results revealed that the BNST was capable of supporting BSR in P but not NP rats. Also, amphetamine pretreatment produced a significant leftward shift in the rate‐frequency function in P rats with significant reductions observed in three other measures of reward threshold, while EtOH only lowered the minimum frequency needed to produce responding. The effects of systemic amphetamine were successfully attenuated by the unilateral infusion of the D1 receptor antagonist SCH 23390 (5.0 μg) into the contralateral nucleus accumbens. The results suggest the BNST is capable of supporting BSR performance in P, but not NP rats, possibly due to increased sensitivity to the electrical stimulation‐induced DA release of BSR in the innately DA “deficient” limbic system of P rats. Synapse 61:912–924, 2007. © 2007 Wiley‐Liss, Inc.
Prenatal stress alters limbo‐corticostriatal homer protein expression
Authors: Ary Alexis W. , Aguilar Valerie R. , Szumlinski Karen K. , Kippin Tod E. 
Published: August 2007

AbstractEarly environmental stress influences developmental processes resulting in alterations in behavior and brain function, including abnormalities in glutamate neurotransmission. Here, we assessed the influence of prenatal stress on limbo‐corticostriatal expression of Homer proteins that are critical elements in glutamatergic signaling. Pregnant, female Sprague–Dawley rats were subjected to either no treatment or to restraint stress 3 times per day for the last 7 days of gestation. At 21 d of age, offspring were sacrificed and brain tissue was rapidly extracted. Immunoblotting revealed regionally specific increases in certain Homer protein isoforms within prefrontal cortex and limbic structures, whereas the striatum exhibited a reduction in Homer 1a levels. These findings indicate that stress during development can produce enduring perturbations in Homer protein expression that likely contribute to glutamatergic and behavioral abnormalities observed following early environmental stress. Synapse 61:938–941, 2007. © 2007 Wiley‐Liss, Inc.
Current Status and Future Perspective of General Surgical Trainees in the Netherlands
Authors: Wijnhoven Bas P. L. , Watson David I. , van den Ende Esther D. 
Published: August 2007

AbstractBackgroundThe opinions of general surgical trainees about their current training program and their future career plans are important because such information can inform any redesign of surgical training programs as well as future surgical manpower planning.MethodsA structured questionnaire was sent to 392 general surgical trainees in the Netherlands in 2005.ResultsA total of 239 (61%) questionnaires were returned by 66 (28%) women and 173 (72%) men, mean age 31.3 years. On average, trainees worked in the hospital 55 hours per week (range: 22–80 h). The mean number of operative cases performed per year was 195 (range 35–450), and this had been stable since the year 2000. The quality of the supervision by staff surgeons was rated satisfactory. The vast majority of the trainees are also satisfied with the current single year of differentiation/specialized training into one of the subspecialties, although most trainees (83%) would like to enroll in a fellowship before taking a job as a consultant. There was also a desire to take maternity/paternity leave during training. Both male and female trainees expressed the wish to work an average of 52 hours per week as a consultant, and they want these hours to occur in 4.1 days of work per week.ConclusionsDutch general surgery trainees are satisfied with their training. They expressed a strong wish for specialization during and after their training. All trainees favored reduced working hours and days of work per week as fully qualified surgeons in the future.
High-calcium diet with whey protein attenuates body-weight gain in high-fat-fed C57Bl/6J mice
Authors: Pilvi Taru K. , Korpela Riitta , Huttunen Minna , Vapaatalo Heikki , Mervaala Eero M. 
Published: August 2007

An inverse relationship between Ca intake and BMI has been found in several studies. It has been suggested that Ca affects adipocyte metabolism via suppressing 1,25-dihydroxycholecalciferol (1,25(OH)2-D3) and decreases fat absorption. We studied the effect of Ca and milk proteins (whey and casein) on body weight in C57Bl/6J mice. Male mice, age 9 weeks, were divided into three groups (ten mice per group) receiving modified high-fat (60 % of energy) diets. Two groups received a high-Ca diet (1·8 % calcium carbonate (CaCO3)), with casein or whey protein (18 % of energy), and one group received a low-Ca diet (0·4 % CaCO3) with casein for 21 weeks. Food intake was measured daily and body weight twice per week. Body fat content (by dual-energy X-ray absorptiometry) of all mice and faecal Ca and fat excretion of seven mice/group were measured twice during the study. Final body weight (44·1 (sem 1·1) g) and body fat content (41·6 (sem 0·6) %) were significantly lower (P < 0·05) in the high-Ca whey group than in the low-Ca casein group (48·1 (sem 0·8) g and 44·9 (sem 0·8) %). Body weight and body fat content of the high-Ca casein group did not differ significantly from the low-Ca casein group even though serum 1,25(OH)2-D3 levels were significantly lower (P < 0·001) in both high-Ca groups than in the low-Ca casein group. Thus changes in serum 1,25(OH)2-D3 do not seem to affect body weight in this animal model. There was a significant difference in fat excretion between the high-Ca whey and low-Ca casein groups (3·9 (sem 0·9) % in the high-Ca whey v. 1·4 (sem 0·2) % in the low-Ca casein group; P < 0·05), which may partly explain the effect on body weight.
Convenience food in the diet of children and adolescents: consumption and composition
Authors: Alexy Ute , Sichert-Hellert Wolfgang , Rode Tabea , Kersting Mathilde 
Published: August 2007

Despite an increasing trend towards the use of convenience food, there is to date little debate on it in the nutritional sciences. In the present study, we present and evaluate data on consumption frequencies and composition of savoury convenience food in German families using data from the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study. The DONALD Study is an ongoing, longitudinal (open cohort) study (started 1985), collecting detailed data on diet, development, and metabolism in infants, children and adolescents. Dietary intake was measured by yearly repeated 3 d weighed dietary records (n 1558) in 554 subjects (278 boys; 276 girls), 3–18 years old, between 2003 and 2006. A total of 1345 (86%) 3 d dietary records mentioned consumption of at least one convenience food. Convenience food consumption (percentage of total food intake, g/d) increased with age from approximately 3% in the 3–8 year olds to 7% in 14–18-year-old boys and 5% in 14–18-year-old girls (P < 0·0001) but remained constant during the study period. Convenience foods contributed more to total fat (g/d) (P < 0·001) and less to total carbohydrate (P < 0·0001) than to total energy (kJ/d) intake. The 700 convenience-food products recorded by our sample had on average fourteen ingredients; 4% were flavourings and 16% were food additives. In conclusion, convenience foods were widely consumed by our sample of German children and adolescents and their consumption increased with age. The composition of convenience food was characterised by a high fat content and a high number of flavourings and food additives.
Effect of folic acid on prenatal alcohol-induced modification of brain proteome in mice
Authors: Xu Yajun , Tang Yunan , Li Yong 
Published: August 2007

Maternal alcohol consumption during pregnancy can induce central nervous system abnormalities in the fetus, and folic acid supplementation can reverse some of the effects. The objective of the present study was to investigate prenatal alcohol exposure-induced fetal brain proteome alteration and the protective effect of folic acid using proteomic techniques. Alcohol (5·0 g/kg) was given intragastrically from gestational day (GD) 6 to15, with or without 60·0 mg folic acid/kg given intragastrically during GD1–16 to pregnant Balb/c mice. The control group received distilled water only. Results of litter evaluation on GD18 showed that supplementation of folic acid reversed the prevalence of microcephaly induced by alcohol. Proteomic analysis indicated that, under the dosage of the present investigation, folic acid mainly reversed the alcohol-altered proteins involved in energy production, signal pathways and protein translation, which are all important for central nervous system development.