bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mass spectrometric characterisation of proteins in rennet and in chymosin‐based milk‐clotting preparations
Authors: Lilla Sergio , Caira Simonetta , Ferranti Pasquale , Addeo Francesco 
Published: August 2002

AbstractThe protein composition of natural rennet and of chromatographic and crystalline chymosin preparations has been defined by on‐line reverse‐phase high performance liquid chromatography/electrospray ionisation mass spectrometry (RP‐HPLC/ESI‐MS) and by tandem mass spectrometry (MS/MS). Natural rennet was found to consist of six chymosin species, corresponding to chymosin A and B genetic variants, each of which comprised a mixture of two other forms differing at theN‐terminal end, with one being three residues longer, and the other two residues shorter, than the mature chymosin. Two main tissue proteins were also identified as lysozyme (isozyme 2 plus a novel isozyme labelled 4) and bovine serum albumin. In addition to the proteins, chymosin fragments 247–323 and 288–323 were consistently present in natural rennet. Conversely, chromatographic and crystalline chymosin preparations lacked bovine serum albumin and/or lysozyme, although they contained the same six chymosin species as natural rennet. Since these tissue‐specific contaminating proteins each possess specific functions in terms of stabilising enzyme solutions and protecting proteins from proteolytic enzymes, oxidising agents and bacterial proliferation, the rennet may be considered as a functional enzyme preparation that is effectively and naturally adapted to the purposes of cheesemaking. In practice, the highly complex protein composition inherent to natural rennet provided the possibility to differentiate the natural product from other bovine chymosin‐based milk‐clotting preparations examined in this work. Copyright © 2001 John Wiley & Sons, Ltd.
Cone voltage and collision cell collision‐induced dissociation study of triphenylethylenes of pharmaceutical interest
Authors: Makowiecki Jacek , Tolonen Ari , Uusitalo Jouko , Jalonen Jorma 
Published: August 2002

AbstractFragmentations of three triphenylethylene compounds (toremifene and its two metabolites) with different functional side‐chain groups (alcohol, acid and amine) were studied. The compounds were dissociated by collision‐induced dissociation (CID) in the interface region of an electrospray ionization source (ESI+) and in the collision cell of a triple quadrupole mass spectrometer. Fragmentation pathways for these molecules are proposed, based on accurate mass measurements of in‐source fragment ions and MS/MS experiments using product and precursor ion scanning. The side‐chain functional groups were found to strongly affect the fragmentations of the molecular ions. The fragmentation pathways of the protonated molecule and sodium ion adduct were quite similar, but the subsequent stabilities of certain common fragments were surprisingly different. Copyright © 2001 John Wiley & Sons, Ltd.
Use of nitrocellulose films for affinity‐directed mass spectrometry for the analysis of antibody/antigen interactions
Authors: Sun Shuqing , Mo Wenjun , Ji Yiping , Liu Shuying 
Published: August 2002

AbstractCombination of affinity extraction procedures with mass spectrometric analyses is termed affinity‐directed mass spectrometry, a technique that has gained broad interest in immunology and is extended here with several improvements from methods used in previous studies. A monoclonal antibody was immobilized on a nitrocellulose (NC) membrane, allowing the corresponding antigen to be selectively captured from a complex solution for analysis by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). This method was also used to rapidly determine the approximate binding region responsible for the antibody/antigen interaction. The tryptic fragments of antigen protein in buffer were applied to the antibody immobilized on NC film and allowed to interact. The NC film was then washed to remove salts and other unbound components, and subjected to analysis by MALDI‐TOFMS. Using interferon‐α2a and anti‐interferon‐α2a monoclonal antibody IgG as a model system, we successfully extracted the antigen protein and determined the approximate binding region for the antigen/antibody interaction (i.e., the tryptic fragment responsible). Copyright © 2001 John Wiley & Sons, Ltd.
Characterization of a [(O3/2SiMe)x(OSi(OH)Me)y(OSiMe2)z] silsesquioxane copolymer resin by mass spectrometry
Authors: Tecklenburg Ron E. , Wallace William E. , Chen Huiping 
Published: August 2002

AbstractElectrospray ionization Fourier transform ion cyclotron resonance (ESI‐FTICR) mass spectrometry and matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry were applied to a complex silsesquioxane‐siloxane copolymer resin. The wide‐polydispersity starting material was fractionated into 21 separate fractions in order to facilitate the analysis by mass spectrometry. ESI‐FTICR exact mass measurements were able to identify the specific oligomers present in the lowest mass fractions and showed that very few unreacted silanol groups remained, that is, topologically closed structures predominated. MALDI‐TOFMS was able to show that gel‐permeation chromatography substantially underestimated the molecular masses of the higher mass fractions. Mass autocorrelation was able to show that the silsesquioxane monomer appeared only in even numbers in any given oligomer. This is a natural consequence of the highly condensed nature of the resin. Copyright © 2001 John Wiley & Sons, Ltd.
On‐target fraction collection for the off‐line coupling of capillary isoelectric focusing with matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Chartogne Anne , Gaspari Marco , Jespersen Sonja , Buscher Brigitte , Verheij Elwin , Heijden Robert van der , Tjaden Ubbo , Greef Jan van der 
Published: August 2002

AbstractIn the present work, we describe a collection system for the off‐line coupling of capillary isoelectric focusing (CIEF) with matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry. In this system, the capillary effluent is directly deposited in fractions onto the MALDI target via the use of a sheath liquid. The collected fractions are subsequently supplemented with matrix and further analysed by MALDI‐TOF mass spectrometry for mass assignment. The experimental set‐up includes a fiber optic based UV detector operating at 280 nm, which allows the study of the influence of the sheath liquid composition on the CIEF separation. The influence of the carrier ampholyte concentration on the protein MALDI spectra was also evaluated and the feasibility of the collection method was finally demonstrated with a mixture of four standard proteins. Copyright © 2002 John Wiley & Sons, Ltd.
Tandem mass spectra of tryptic peptides at signal‐to‐background ratios approaching unity using electrospray ionization high‐field asymmetric waveform ion mobility spectrometry/hybrid quadrupole time‐of‐flight mass spectrometry
Authors: Barnett David A. , Ding Luyi , Ells Barbara , Purves Randy W. , Guevremont Roger 
Published: August 2002

AbstractHigh‐field asymmetric waveform ion mobility spectrometry (FAIMS) has been coupled to a quadrupole time‐of‐flight mass spectrometer for the tandem mass spectrometric analysis of tryptic peptides of pig hemoglobin. Using FAIMS, low levels (fmol/µL) of multiply charged tryptic peptides were separated from relatively intense chemical background such that their tandem mass spectra (MS/MS) lacked many background‐related fragment ions observed using a conventional ESI‐QqTOFMS instrument. Substantial improvements in both first‐order and tandem mass spectra were realized while maintaining approximately the same absolute intensities. Copyright © 2002 John Wiley & Sons, Ltd.
Robust control of multi‐axis magnetic bearing systems
Authors: Yeh T.‐J. , Chung Ying‐Jer , Wu Wei‐Chung 
Published: August 2002

AbstractThis paper proposes robust control schemes for multi‐axis magnetic bearing systems under current control and voltage control. The control schemes are based on a model which characterizes not only the electromagnetic interaction but also secondary effects such as flux leakage, fringing fluxes, and finite core permeance in the magnetic bearing. In the current control case, a sliding‐mode‐based robust controller, whose control parameters have to be deliberately chosen to account for the uni‐directionality of magnetic forces, is proposed to provide robust performance against uncertain dynamics. In the voltage control case, a control scheme that combines the sliding methodology and the backstepping technique is used to provide robust performance under the influence of the electrical dynamics. It is demonstrated through simulations and experiments that, because the nonlinearity and the uncertainty inherently residing in the system behaviour are directly tackled, the proposed controllers achieve superior tracking performances compared to control lers based on linearization. Copyright © 2001 John Wiley & Sons, Ltd.
Use of mesohabitat‐specific relationships between flow velocity and river discharge to assess invertebrate minimum flow requirements
Authors: Brunke Matthias , Hoffmann Andreas , Pusch Martin 
Published: August 2002

AbstractThe benthic macroinvertebrate community in the sixth order lowland River Spree (Germany) was investigated in order to assess ecological effects of a flow reduction. The benthic habitat was composed of visually distinguishable mesohabitats. Eight mesohabitats were delineated, Dreissena‐bank, unionid mussel bed, rip‐rap, coarse woody debris (CWD), alder roots, stable sand, shifting sand and mud. The mesohabitats differed in their physical structure and hydraulic nature. These functional habitats were partly inhabited by distinct invertebrate assemblages. The use of mesohabitat‐specific relationships between flow velocity and discharge seemed the most appropriate approach in order to assess the impact of flow reduction on lotic fauna. In combination with the species‐specific optima and tolerances for flow velocity, this approach can be used to develop a minimum flow level that mitigates the effects of flow reduction and enables the persistence of rheophilic invertebrates in their specific mesohabitat. Copyright © 2001 John Wiley & Sons, Ltd.
Understanding students' explanations of biological phenomena: Conceptual frameworks or p‐prims?
Authors: Southerland Sherry A. , Abrams Eleanor , Cummins Catherine L. , Anzelmo Julie 
Published: August 2002

AbstractThis study explores two differing perspectives of the nature of students' biological knowledge structures, conceptual frameworks, and p‐prims. Students from four grade levels and from three regions of the United States were asked to explain a variety of biological phenomena. Students' responses to the interview probes were analyzed to describe 1) patterns in the nature of students' explanations across grade levels and interview probes, and 2) the consistency of students' explanations across individual interview probes and across the range of probes. The results were interpreted from both perspectives of knowledge structures. While definitive assertions supporting either perspective could not be made, each hypothesis was explored. Although the more prevalent description of student conceptions within a broader conceptual framework could not be discounted, the p‐prim of need as a rationale for change was also found to offer a useful description of knowledge frameworks for this content area. The difficulties endemic to the use of biology for the study of basic knowledge structures are also discussed. © 2001 John Wiley & Sons, Inc. Sci Ed 85:328–348, 2001.
Charge writing on the nanometre scale in a fluorocarbon film
Authors: Mesquida P. , Knapp H. F. , Stemmer A. 
Published: August 2002

AbstractBy applying voltage pulses to an atomic force microscopy cantilever, nanometre‐scale charge patterns were written onto an electret surface consisting of a fluorocarbon layer grown by plasma‐enhanced chemical vapour deposition on substrates with different electric conductivities. Kelvin probe force microscopy then was used to assess quantitatively the parameters relevant for optimal charge storage properties. Pulse height and duration, layer thickness and substrate, as well as the surrounding media, were varied to optimize the size of the charge patterns and their lifetime. By applying pulses of 100 µs and 25 V, lifetimes of several days were achieved with 20 nm thick fluorocarbon layers on p‐doped silicon as the underlying substrate. Our process also allowed us to create localized charge patterns on metal substrates. Furthermore, for the first time, nanoscale charge patterns have been written in a liquid environment that can be used as carrier substance for particles. Copyright © 2002 John Wiley & Sons, Ltd.
A comparison of several methods to test for the existence of a monotonic dose–response relationship in clinical and epidemiological studies
Authors: Leuraud Klervi , Benichou Jacques 
Published: August 2002

AbstractThe Mantel‐extension chi‐square test for overall trend and an asymptotically equivalent test based on logistic regression are commonly used to test for a monotonic dose–response relationship between exposure and disease in epidemiological and clinical studies. However, these tests present two important disadvantages, as they (i) make the restrictive assumption of a parametric model of linear form on the logit scale and (ii) impose the a priori choice of scores to code for the exposure categories. Indeed, the linear assumption, if made incorrectly, can lead to an invalid conclusion, and the choice of scores lends arbitrariness to the test results. Some alternative tests have been proposed in the literature. We have considered several of these tests, namely one based on isotonic regression, the T‐test based on contrasts and a recently published test based on adjacent contrasts (Dosemeci–Benichou test). The aim of our study was to compare the statistical properties (type I error and power) of these tests and of the commonly used Mantel‐extension test for overall trend. We generated cohort and case‐control data and considered one‐ and two‐sided versions of the tests. Moreover, we studied the tests under the null hypothesis of no relationship between exposure and disease and under various alternative patterns of monotonic or non‐monotonic dose–response relationships. This study confirms that the commonly used trend tests can lead to erroneous conclusion of a monotonic dose–response relationship. The test based on isotonic regression does not represent a favourable alternative, as it tends to be too powerful in case of non‐monotonic dose–response relationship patterns. The tests based on contrasts seem to possess more favourable properties by combining close to nominal type I error, high power for monotonic alternatives and low power for non‐monotonic alternatives. Copyright © 2001 John Wiley & Sons, Ltd.
Ultrastructural immunocytochemical localization of the dopamine D2 receptor and tyrosine hydroxylase in the rat ventral pallidum
Authors: Mengual Elisa , Pickel Virginia M. 
Published: August 2002

AbstractThe mesopallidal dopamine system plays a role in locomotor activity and reward. To understand the potential contribution of the dopamine D2 receptor (D2R) to the action of dopamine in the ventral pallidum (VP), we used electron microscopic immunocytochemistry to examine the cellular and subcellular localization of an antipeptide antiserum against the D2R in both ventromedial and dorsolateral VP compartments. In each region the majority of the total D2R‐labeled profiles (n = 1,132) were axon terminals (55%) and small unmyelinated axons (27%). These terminals were often apposed to other axon terminals or dendrites and formed almost exclusively symmetric, inhibitory‐type axodendritic synapses. Immunogold D2R labeling in axon terminals was seen on the plasmalemma and membranes of nearby synaptic vesicles. In ventral pallidal sections processed for dual detection of D2R peptide and the catecholamine‐synthesizing enzyme tyrosine hydroxylase (TH), D2R labeling was detected in a few axons and axon terminals containing TH immunoreactivity as well as in axons contacted by TH‐labeled terminals. In most cases, however, the D2R‐labeled profiles were located at a distance from small axons and terminals containing TH. Our results provide the first ultrastructural evidence that D2Rs in the two VP subterritories are strategically located for primary involvement in modulation of the presynaptic release of nondopaminergic inhibitory transmitters. They also suggest that in this region the presynaptic D2 receptors are 1) minimally involved in autoregulation of dopaminergic transmission, and 2) differentially activated by dopamine, depending in part on levels and distance from release sites. Synapse 43:151–162, 2002. © 2002 Wiley‐Liss, Inc.
Seismic isolation design of the Arrowhead Regional Medical Center
Authors: Asher J. W. , Young R. P. , Ewing R. D. 
Published: August 2002

AbstractThe Arrowhead Regional Medical Center, located in Colton, CA, consists of six separate building structures containing a total of approximately 920 000 square foot of floor space for hospital and support services. Five of the six buildings are base‐isolated. Each of the five base‐isolated buildings is of different size and configuration, ranging from a six‐storey, 360 000‐square‐foot curved‐front nursing tower to a two‐storey, 24 000‐square‐foot rectangular shaped central plant building. The building structures are framed with structural steel, utilizing concentric braced frames as the lateral force resisting system. The design ground motion for the site, which is located 3 km and 15 km from the San Jacinto and San Andreas faults, respectively, is very severe. A base‐isolation system has been designed for this facility that will provide essentially elastic building response to the design strong ground motion. The base‐isolation system is a hybrid passive energy dissipation system consisting of both linear and nonlinear and high damping rubber bearings along with viscous damping devices located at the base of the structure. The high damping rubber bearings provide both lateral stiffness, which governs the fundamental period of vibration of the system and hysteretic damping, while the viscous damping devices provide velocity‐dependent damping, which serves to control overall building displacements. This will maximize the probability that this essential facility will remain fully operational after a major earthquake. Design criteria, structural analysis and design methodologies, and construction details are presented and discussed. The response of one of the base‐isolated structures is calculated utilizing actual recorded ground motions from the 1994 Northridge Earthquake. Copyright © 2001 John Wiley & Sons, Ltd.
Optimization of K‐shell intensity ratios in electron probe microanalysis
Authors: Castellano G. , Bonetto R. , Trincavelli J. , Vasconcellos M. , Campos C. 
Published: August 2002

AbstractA method for refinement of atomic and experimental parameters was applied to the optimization of K‐shell intensity ratios in electron probe microanalysis (EPMA). This kind of procedure, previously used in x‐ray diffraction, is shown to be a powerful tool in EPMA. The method consists of minimizing the differences between an experimental x‐ray spectrum and a function proposed to account for the bremsstrahlung and characteristic peaks from the corresponding sample, and also for detection artifacts. In this work, the method was used for the determination of transition rates. This procedure was applied to 14 elements with atomic numbers ranging from 20 to 42. The results obtained are in agreement with theoretical and experimental data for Kα/(Kβ+ Kα) intensity ratios. In addition, Kα1, Kα2, Kβ1, and Kβ2relative intensities were compared with experimental data, showing a similar behaviour. Copyright © 2002 John Wiley & Sons, Ltd.
Yeast Lrg1p acts as a specialized RhoGAP regulating 1,3‐β‐glucan synthesis
Authors: Watanabe Daisuke , Abe Mitsuhiro , Ohya Yoshikazu 
Published: August 2002

AbstractSelection of an extragenic suppressor of fks1‐1154 Δfks2, mutations in the catalytic subunits of yeast 1,3‐β‐glucan synthase (GS) conferring temperature‐sensitivity, led to the LRG1 gene, which was originally identified as a LIM‐RhoGAP homologous gene. Mutations in the LRG1 gene restore impaired 1,3‐β‐glucan synthesis in the fks1‐1154 Δfks2 mutant as well as that in rho1‐2, a temperature‐sensitive mutant of Rho‐type GTPase that functions as a regulatory subunit of GS. Two‐hybrid analyses of Lrg1p, which contains a sequence conserved among Rho GTPase‐activating proteins (GAPs), revealed its specific interactions with the active form of Rho1p. Among eight potential yeast RhoGAPs, Lrg1p is the only member that negatively regulates GS activity: mutations in the rest of GAPs, including bem2, Δbem3, Δsac7, Δbag7, Δrga1, Δrga2 and Δrgd1, do not suppress impairment of 1,3‐β‐glucan synthesis. Analyses of Mpk1p phosphorylation revealed the inability of Lrg1p to regulate the Pkc1p–MAP kinase cascade, a distinct Rho1p‐regulating signalling pathway known to be affected by the GAPs, Bem2p and Sac7p. Thus, different groups of Rho1p GAPs control the activity of different Rho1p‐effector proteins. Copyright © 2001 John Wiley & Sons, Ltd.
Role of the Nha1 antiporter in regulating K+ influx in Saccharomyces cerevisiae
Authors: Bañuelos María A. , Ruiz María C. , Jiménez Adriana , Souciet Jean‐Luc , Potier Serge , Ramos José 
Published: August 2002

AbstractNHA1 encodes a K+ (Na+)/H+ antiporter in the plasma membrane of Saccharomyces cerevisiae. We report that cells expressing the NHA1 gene contained less K+ than the mutant lacking the gene when grown without K+ limitation. They also grew better at low K+ and showed higher affinity of transport than the nha1 strain. In agreement with the function of an electroneutral cation/H+ antiporter, the effect was only observed at acidic pH. The improved growth and transport depended on the presence of Trk1p (the main K+ influx system) and did not require the product of TRK2. We propose that Nha1p regulates the potassium content of the cell and, as a consequence, can affect the activity of the main K+ influx system (Trk1p). Copyright © 2002 John Wiley & Sons, Ltd.
Tools for the study of genome rearrangements in laboratory and industrial yeast strains
Authors: Lockhart Lesley , Oliver Stephen G. , Delneri Daniela 
Published: August 2002

AbstractIn order to investigate the extent of genome rearrangements in laboratory and industrial yeast strains, a set of plasmids, containing ca. 300 bp fragments from highly conserved genes from S. cerevisiae, has been constructed. We chose three unique PCR products, each from a single gene, per chromosome: one from close to the centromere, and one from each chromosome end. Using these plasmids as probes to hybridize a Southern blot from a pulsed‐field gel electrophoresis separation of the 16 yeast chromosomes, it is possible to identify large chromosomal rearrangements such as reciprocal translocations. Copyright © 2002 John Wiley & Sons, Ltd.