bluuebunny/crossref_metadata_2025_split huggingface dataset:
Erythroblast iron metabolism and serum soluble transferrin receptor values in the anemia of rheumatoid arthritis
Authors: Fitzsimons Edward J. , Houston Tracey , Munro Robin , Sturrock Roger D. , Speekenbrink Anthony B. J. , Brock Jeremy H. 
Published: August 2002

AbstractObjectivesWe have investigated in vitro erythroblast iron metabolism in the anemia of rheumatoid arthritis (RA). We also have examined the results in relation to bone marrow iron status in an attempt to explain the reported difference between serum soluble transferrin receptor (sTfR) values in anemia of chronic disease (ACD) and iron deficiency anemia (IDA) in patients with RA.MethodsBone marrow was examined in 29 anemic patients with RA, 9 healthy volunteers, and 6 patients with simple IDA. High purity erythroblast fractions were prepared from these bone marrow samples. Erythroblast surface TfR expression and iron uptake was assessed in vitro using 125I‐transferrin (Tf) and 59Fe‐Tf, respectively. The efficiency of erythroblast surface TfR function for Tf‐iron uptake was determined by relating total iron uptake at 4 hours to surface TfR number. Serum sTfR values were measured for the RA anemia group, which was subdivided as RA‐ACD (marrow iron present) or RA‐IDA (marrow iron absent) on the basis of visible reticuloendothelial (RE) marrow iron stores.ResultsHigh purity (87 ± 5%) erythroblast fractions were obtained from 35 of the 44 marrow samples. Erythroblasts obtained from patients with simple IDA showed a significant increase in surface TfR expression (P = 0.0003) and Tf‐iron uptake (P = 0.001). RA anemia also led to a significant increase in erythroblast Tf‐iron uptake (P = 0.016). This increase was not associated with an increase in surface TfR expression (P = 0.5), but was seen to occur as a result of a significant increase in the efficiency of surface TfR for Tf‐iron uptake (P = 0.027). Within the RA anemia group, the increase in erythroblast Tf‐ iron uptake at 4 hours was more evident for RA‐IDA (3.96 ± 1.73 versus 1.66 ± 0.66; P = 0.03) than for RA‐ACD (2.69 ± 1.18 versus 1.66 ± 0.66; P = 0.057). This additional erythroblast response to absent RE iron stores led to a highly significant difference in serum sTfR values between RA‐IDA and RA‐ACD (40.2 ± 14.0 versus 23.9 ± 5.3 nmoles/liter; P = 0.001)ConclusionsAn increase in erythroblast surface TfR efficiency for Tf‐iron uptake compensates for the low plasma iron levels associated with anemia in RA and helps to maintain RA erythroblast iron uptake. With adequate RE iron stores, this increased efficiency limits intracellular iron deprivation and consequently reduces the need to increase surface TfR expression. As a result, serum sTfR levels in RA‐ACD remain within the normal range. RA erythroblasts, however, are still able to respond to any additional worsening of the iron supply caused by absent RE iron stores. This additional response causes the highly significant increase in serum sTfR values seen between RA‐IDA and RA‐ACD.
A survey in indexing and searching XML documents
Authors: Luk Robert W.P. , Leong H.V. , Dillon Tharam S. , Chan Alvin T.S. , Croft W. Bruce , Allan James 
Published: August 2002

AbstractXML holds the promise to yield (1) a more precise search by providing additional information in the elements, (2) a better integrated search of documents from heterogeneous sources, (3) a powerful search paradigm using structural as well as content specifications, and (4) data and information exchange to share resources and to support cooperative search. We survey several indexing techniques for XML documents, grouping them into flat‐file, semistructured, and structured indexing paradigms. Searching techniques and supporting techniques for searching are reviewed, including full text search and multistage search. Because searching XML documents can be very flexible, various search result presentations are discussed, as well as database and information retrieval system integration and XML query languages. We also survey various retrieval models, examining how they would be used or extended for retrieving XML documents. To conclude the article, we discuss various open issues that XML poses with respect to information retrieval and database research.
On the shape of the mean residual lifetime function
Authors: Finkelstein M. S. 
Published: August 2002

AbstractSome general properties of the mean residual life (MRL) function are studied. The analysis is based on the shape of the corresponding failure rate. The conditions under which the failure rate and the reciprocal to the MRL function have asymptotically equivalent behaviour as t→∞ are discussed. The simplest non‐monotone shapes of the functions under consideration (bathtub and upside down bathtub) are also considered. The MRL functions for mixtures of distributions are described via the corresponding conditional probability density functions. The direct proportional model of mixing is characterized and some asymptotic results on the shape of the mixture MRL are obtained. Some simple examples are given. Copyright © 2002 John Wiley & Sons, Ltd.
The proportion heuristic: problem set size as a basis for performance judgments
Authors: Silvera David H. , Josephs Robert A. , Giesler R. Brian 
Published: August 2002

AbstractHow do people evaluate their degree of mastery over a task? A series of four studies demonstrated that a potentially irrelevant cue can have a strong influence on such evaluations. In these studies, the total amount of work given to participants (the problem set size) influenced both (a) the amount of work participants completed before feeling that they had performed well and were adequately prepared for a related future task, and (b) participants' assessments of their performance and their feelings of preparedness for a related future task. These effects occurred even when a randomization procedure was used to emphasize the arbitrary nature of the problem set size. The effects vanished, however, when participants were given extra time to evaluate their progress after completing each problem. Copyright © 2001 John Wiley & Sons, Ltd.
Calculation of electric fields induced in the human knee by a coil applicator
Authors: Buechler D.N. , Christensen D.A. , Durney C.H. , Simon B. 
Published: August 2002

AbstractCalculations are presented of the induced electric fields and current densities in the cartilage of the knee produced by a coil applicator developed for applying pulsed magnetic fields to osteoarthritic knees. This applicator produces a sawtooth‐like magnetic field waveform composed of a series of 260‐μs pulses with a peak to peak magnitude of approximately 0.12 mT in the cartilage region. The simulations were performed using a recently developed 3 dimensional finite difference frequency domain technique for solving Maxwell's equations with an equivalent circuit model. The tissue model was obtained from the anatomically segmented human body model of Gandhi. The temporal peak electric field magnitude was found to be −153 mV/m, averaged within the medial cartilage of the knee for the typical dB/dt excitation levels of this coil. The technique can be extended to analyze other excitation waveforms and applicator designs. Bioelectromagnetics 22:224–231, 2001. © 2001 Wiley‐Liss, Inc.
Haploid all the way: a new style of asexuality revealed in animals
Authors: Perrot Véronique 
Published: August 2002

AbstractWeeks et al(1) recently reported that they had found a species of mites where the parthenogenetic females are haploid. They show that this is caused by intracellular bacteria that turn genetic haploid males into haploid females. I discuss these findings and attempt to place these observations in evolutionary context. BioEssays 24:114–118, 2002. © 2002 Wiley Periodicals, Inc.
Bacterial actins? An evolutionary perspective
Authors: Doolittle Russell F. , York Amanda L. 
Published: August 2002

AbstractAccording to the conventional wisdom, the existence of a cytoskeleton in eukaryotes and its absence in prokaryotes constitute a fundamental divide between the two domains of life. An integral part of the dogma is that a cytoskeleton enabled an early eukaryote to feed upon prokaryotes, a consequence of which was the occasional endosymbiosis and the eventual evolution of organelles. Two recent papers1, 2 present compelling evidence that actin, one of the principal components of a cytoskeleton, has a homolog in Bacteria that behaves in many ways like eukaryotic actin. Sequence comparisons reveal that eukaryotic actin and the bacterialhomolog (mreB protein), unlike many other proteins common to eukaryotes and Bacteria, have very different and more highly extended evolutionary histories. BioEssays 24:293–296, 2002. ©2002 Wiley Periodicals, Inc.
Toward reconstitution of in vivo microtubule dynamics in vitro
Authors: Andersen Søren S. L. , Wittmann Torsten 
Published: August 2002

AbstractThe transition from interphase to mitosis is marked by a dramatic change in microtubule dynamics resulting in the reorganization of the microtubule network that culminates in mitotic spindle formation. While the molecular basis for this change in microtubule organization remains obscure, it is currently thought that a balance in the activity of microtubule stabilizing and destabilizing factors regulates how dynamic cellular microtubules are. By mixing the microtubule stabilizer XMAP215 and the microtubule destabilizer XKCM1, reconstitution of in vivo‐like microtubule dynamics has now been achieved in vitro.(1) BioEssays 24:305–307, 2002. ©2002 Wiley Periodicals, Inc.
Sound silencing: the Sir2 protein and cellular senescence
Authors: Defossez Pierre‐Antoine , Lin Su‐Ju , McNabb David S. 
Published: August 2002

AbstractThe model organism Saccharomyces cerevisiae is providing new insights into the molecular and cellular changes that are related to aging. The yeast protein Sir2p (Silent Information Regulator 2) is a histone deacetylase involved in transcriptional silencing and the control of genomic stability. Recent results have led to the identification of Sir2p as a crucial determinant of yeast life span. Dosage, intracellular localization, and activity of Sir2p all have important effects on yeast longevity. For instance, calorie restriction apparently increases yeast life span by increasing Sir2p activity. Since Sir2p‐related proteins have been identified in many prokaryotic and eukaryotic organisms, the fundamental principles derived from the studies in yeast may prove valuable in directing our future research toward an understanding of the mechanisms of aging in higher eukaryotes. BioEssays 23:327–332, 2001. © 2001 John Wiley & Sons, Inc.
Glial cell development in the Drosophila embryo
Authors: Jones Bradley W. 
Published: August 2002

AbstractGlial cells play a central role in the development and function of complex nervous systems. Drosophila is an excellent model organism for the study of mechanisms underlying neural development, and recent attention has been focused on the differentiation and function of glial cells. We now have a nearly complete description of glial cell organization in the embryo, which enables a systematic genetic analysis of glial cell development. Most glia arise from neural stem cells that originate in the neurogenic ectoderm. The bifurcation of glial and neuronal fates is under the control of the glial promoting factor glial cells missing. Differentiation is propagated through the regulation of several transcription factors. Genes have been discovered affecting the terminal differentiation of glia, including the promotion glial–neuronal interactions and the formation of the blood–nerve barrier. Other roles of glia are being explored, including their requirement for axon guidance, neuronal survival, and signaling. BioEssays 23:877–887, 2001. © 2001 John Wiley & Sons, Inc.
Hindbrain patterning revisited: timing and effects of retinoic acid signalling
Authors: Begemann Gerrit , Meyer Axel 
Published: August 2002

AbstractRetinoids play a critical role in patterning, segmentation, and neurogenesis of the posterior hindbrain and it has been proposed that they act as a posteriorising signal during hindbrain development. Until now, direct evidence that endogenous retinoid signalling acts through a gradient to specify cell fates along the anteroposterior axis has been missing. Two recent studies tested the requirement for retinoid signalling in the developing hindbrain through systematic application of a pan‐retinoic acid receptor antagonist.(1,2) They demonstrate a stage‐dependent requirement for increasing retinoid signalling activity along the hindbrain that proceeds from anterior to posterior. Together these findings challenge the concept of a stable gradient of retinoic acid across the hindbrain and warrant a re‐interpretation of the phenotypes obtained by genetic and nutritional disruption of retinoid signalling in the amniote embryo. BioEssays 23:981–986, 2001. © 2001 John Wiley & Sons, Inc.
A comparative study of bovine blood and milk neutrophil functions with luminol‐dependent chemiluminescence
Authors: Mehrzad Jalil , Dosogne Hilde , Vangroenweghe Frédéric , Burvenich Christian 
Published: August 2002

AbstractIn this study, a technique was developed for the chemiluminescence (CL) measurement of bovine milk polymorphonuclear leukocytes (PMN). In the first study, the effects of cell number and the concentration of phorbol‐12‐myristate‐13‐acetate (PMA), luminol, latex bead particles, dimethyl sulphoxide (DMSO) and gelatin on the luminol‐dependent cellular CL (LDCL) response were assessed with healthy cows in different stages of lactation. In the second study, the LDCL andin vitrobactericidal activity of blood and milk PMN towardsStaphylococcus aureuswas investigated. In general, the CL activity of blood PMN was consistently higher than that of milk PMN. We found that (a) the optimal cell density in blood and milk cells for maximal LDCL response ranged from 1.5 × 106to 5 × 106cells/mL; (b) the optimal concentrations of PMA, latex beads and luminol for maximal LDCL response were 100–200 ng/ml, 500 particles/PMN and 0.1 mmol/L, respectively. Concentrations of DMSO of 0.5–1% (v/v) did not significantly affect the maximal CL response of PMN. Gelatin concentrations of 0.1 –0.5 mg/ml had no effect on the LDCL of PMN. In addition, the LDCL of PMN was significantly correlated with bactericidal activity towardsS. aureus(r = 0.78,p < 0.001 for blood PMN andr = 0.66,p < 0.01 for milk PMN). Under the optimal experimental conditions for measurement of CL produced by bovine blood and milk PMN defined in this study, LDCL assay is an accurate and reproducible technique for the rapid quantification of PMN bactericidal activity in physiological and pathological conditions of high‐yielding dairy cows. Copyright © 2001 John Wiley & Sons, Ltd.
Dynamics of supercoiled and linear pTZ18U plasmids observed with a long‐lifetime metal–ligand complex
Authors: Kang Jung Sook , Abugo Omoefe O. , Lakowicz Joseph R. 
Published: August 2002

AbstractThe metal–ligand complex, [Ru(bpy)2(dppz)]2+ (bpy = 2,2′‐bipyridine, dppz = dipyrido[3,2‐a:2′,3′‐c]phenazine) (Ru‐BD), was used as a spectroscopic probe for studying nucleic acid dynamics. The Ru‐BD complex displays a long lifetime of over 100 ns and a molecular light switch property upon DNA binding due to shielding of its dppz ligand from water. To further show the usefulness of this luminophore (Ru‐BD) for probing DNA dynamics, we examined its intensity and anisotropy decays when intercalated into supercoiled and linear pTZ18U plasmids using frequency‐domain fluorometry with a light‐emitting diode (LED) as the modulated light source. Compared to the supercoiled plasmids with an average intensity decay time of 120.8 ns at 25°C, we obtained somewhat longer lifetimes for the linear plasmids (〈τ〉 = 141.4 ns at 25°C), suggesting a more efficient shielding from water by the linear plasmids. The anisotropy decay data also showed longer rotational correlation times for the linear plasmids (495 and 35 ns at 25°C) as compared to the supercoiled plasmids (412 and 27 ns at 25°C). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the plasmids, respectively. The anisotropy values were quite similar, although the values of the supercoiled plasmids were slightly higher in both the steady‐state and anisotropy decay measurements. These results indicate that Ru‐BD can be applied in the study of both bending and torsional dynamics of nucleic acids. © 2002 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 67: 121–128, 2002
Protein unfolding during reversed‐phase chromatography: I. Effect of surface properties and duration of adsorption
Authors: McNay Jennifer L. M. , Fernandez Erik J. 
Published: August 2002

AbstractResidue‐level features of bovine pancreatic trypsin inhibitor (BPTI) unfolding on reversed‐phase chromatography (RPC) surfaces were investigated using hydrogen–deuterium exchange labeling and NMR. A set of silica‐based RPC surfaces was used to examine the influence of alkyl chain length and media pore size on adsorbed BPTI conformation. In all cases there was substantial unfolding in the adsorbed state; however, residual protection from exchange was consistently observed. Particle pore size did not influence conformation substantially for C4‐alkyl modified silica; however, 120 Å pore C18 media produced more hydrogen exchange than any other surface examined. In this case, the radius of curvature inside the pore approaches the size of the BPTI molecule. Generally, the pattern of hydrogen exchange protection was uniform; however, the β‐sheet region was selectively protected on the large‐pore C18 media. The β‐sheet region forms a hydrophobic core that forms early when BPTI folds in solution. This suggests that partially unfolded states possessing a native‐like structure play an important role in adsorption and elution in RPC. Finally, increased contact time with the surface before elution fostered unfolding and altered chromatographic behavior considerably. © 2001 John Wiley & Sons, Inc. Biotechnol. Bioeng. 76: 224–232, 2001.
Biokinetic models for representing the complete inhibition of microbial activity at high substrate concentrations
Authors: Alagappan Gunaseelan , Cowan Robert M. 
Published: August 2002

AbstractThis paper reintroduces the Wayman and Tseng model for representing substrate inhibition effects on specific growth rate by further documenting its potential predictive capabilities. It also introduces a modification to this model in which an Andrews inhibition function is used in place of the Monod noninhibitory substrate function. This modification better represents the relationship between specific growth rate and substrate concentration for those substrates that show Andrews type inhibition at lower substrate concentrations, rather than the Monod type noninhibitory behavior described in the model of Wayman and Tseng. Results from nonlinear, least squares regression analysis are used to evaluate the ability of these models to empirically represent experimental data (both new and from the literature). The statistical goodness of fit is evaluated by comparing the regression results against those obtained using other empirical models. Finally, possible mechanisms of toxicity responsible for the observed inhibition trends are used to further justify use of these empirical models. The dominant mechanism considered to be relevant for conceptually explaining complete inhibition at high concentrations of solvents is the deterioration of cell membrane integrity. Literature citations are used to support this argument. This work should lead to improvements in the mathematical modeling of contaminant fate and transport in the environment and in the simulation of microbial growth and organic compound biodegradation in engineered systems. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 393–405, 2001.
Stoichiometry and kinetics of acetate uptake under anaerobic conditions by an enriched culture of phosphorus‐accumulating organisms at different pHs
Authors: Filipe Carlos D. M. , Daigger Glen T. , Grady C. P. Leslie 
Published: August 2002

AbstractThe effect of pH on the stoichiometry and kinetics of acetate uptake by phosphorus‐accumulating organisms (PAOs) was studied. The stoichiometry of glycogen consumption and poly‐β‐hydroxy‐alkanoates (PHA) accumulation was independent of the pH over the range 6.5 to 8.0. It was again demonstrated that the amount of phosphorus released per acetate taken up (P/Hac ratio) was linearly dependent on pH, because of additional energy requirements for acetate transport at higher pH. The slope of this relationship was similar to that in previously published work, but the absolute values were different, indicating that the P/Hac ratio is the most variable stoichiometric parameter associated with the anaerobic metabolism of PAOs. A kinetic expression for acetate‐uptake rate was developed and tested. It assumes a zero‐order form when the polyphosphate content of the biomass is not limiting. When the polyphosphate content becomes low, the rate is significantly decreased. The expression was tested in situations in which polyphosphate was a limiting factor in the rate of acetate uptake, in which the glycogen content of the biomass became very low, and in which both glycogen and polyphosphate were present in excess. The model was able to simulate the three situations adequately. Additionally, the rate of acetate uptake was independent of the pH for the range studied (6.5 to 8.0). © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 32–43, 2001.
Primary recovery of a genetically engineered Trichoderma reesei endoglucanase I (Cel 7B) fusion protein in cloud point extraction systems
Authors: Collén Anna , Selber Klaus , Hyytiä Teppo , Persson Josefine , Nakari‐Setlä Tiina , Bailey Michael , Fagerström Richard , Kula Maria‐Regina , Penttilä Merja , Stålbrand Henrik , Tjerneld Folke 
Published: August 2002

AbstractHere we present data to demonstrate how partitioning of a hydrophilic enzyme can be directed to the hydrophobic detergent‐enriched phase of an aqueous two‐phase system by addition of short stretches of amino acid residues to the protein molecule. The target enzyme was the industrially important endoglucanase I, EGI (endo‐1,4‐β‐D‐glucan‐4‐glucanohydrolase, EC 3.2.1.4, Cel7B) of Trichoderma reesei. We investigated the partitioning of three EGI variants containing various C‐terminal peptide extensions including Trp‐Pro motifs of different lengths and localizations. Additionally, a recently developed system composed of the thermoseparating copolymer HM‐EOPO was utilized to study the effects of fusion tags. The addition of peptides containing tryptohan residues enhanced the partitioning of EGI to the HM‐EOPO‐rich phase. The system composed of a nonionic detergent (Agrimul NRE1205) resulted in the highest partition coefficient (K = 31) and yield (90%) with the construct EGIcore‐P5(WP)4 containing (Trp‐Pro)4 after a short linker stretch. A recombinant strain of T. reesei Rut‐C30 for large‐scale production was constructed in which the fusion protein EGIcore‐P5(WP)4 was expressed from the strong promoter of the cellulase gene cbh1. The fusion protein was successfully expressed and secreted from the fungus during shake‐flask cultivations. Cultivation in a 28‐L bioreactor however, revealed that the fusion protein is sensitive to proteases. Consequently, only low production levels were obtained in large‐scale production trials. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 385–394, 2002.