bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stages of embryonic development in the Atlantic cod Gadus morhua
Authors: Hall Thomas E. , Smith Peter , Johnston Ian A. 
Published: February 2004

AbstractThe early development of the Atlantic cod, Gadus morhua was studied from fertilization until first‐feeding. Multiple families were reared at 7°C and a developmental staging series was prepared using morphological landmarks visible with the light microscope. Stages were named rather than numbered to allow for future additions and broadly grouped into larger time intervals called periods. The most useful staging features were found to be initially cell number, and later in development, somite number. The mean cell cycle time for the first six cleavages was 135 min and the linear regression equation for development of somites(s) over time (t) was s = 0.29t – 18.14. The segmentation period began at 220 h postfertilization (hpf), and unlike some other teleosts, the addition of new somites continued throughout the majority of embryonic development, until just prior to hatching. Hatching occurred at 256 hpf, after which individuals remained motionless at the water's surface, undergoing negative phototaxis only after the first day posthatch. The first‐feeding stage was reached at the end of the third day posthatch, subsequent to development of a functional jaw and hindgut. This staging series provides an essential baseline reference for future experiments involving developing cod embryos and for the aquaculture industry. J. Morphol. 259:255–270, 2004. © 2004 Wiley‐Liss, Inc.
Quantification of T2 relaxation changes in articular cartilage with in situ mechanical loading of the knee
Authors: Nag David , Liney Gary P. , Gillespie Paul , Sherman Kevin P. 
Published: February 2004

AbstractPurposeTo devise a method for producing in vivo MRI images of the knee under physiologically significant loading, and to compare and evaluate the changes in cartilage characteristics before and during in situ compression of the knee.Material and MethodsA total of 26 asymptomatic subjects were imaged on a 1.5 Tesla Philips Intera scanner using a commercially available knee coil. Routine anatomical images were followed by T2 map acquisition. These scans were repeated following in situ compression of the knee using a MR compatible loading jig.ResultsFollowing loading to body weight, several regions of femoral cartilage show early alteration of T2 relaxation time, most significantly in the medial and lateral peripheral zones. There were no significant changes in the tibial cartilage.ConclusionsThe results establish the feasibility of measuring changes on MRI with in situ axial loading. J. Magn. Reson. Imaging 2004;19:317–322. © 2004 Wiley‐Liss, Inc.
Nikola Tesla: The man behind the magnetic field unit
Authors: Roguin Ariel 
Published: February 2004

AbstractThe magnetic field strength of both the magnet and gradient coils used in MR imaging equipment is measured in Tesla units, which are named for Nikola Tesla. This article presents the life and achievements of this Serbian‐American inventor and researcher who discovered the rotating magnetic field, the basis of most alternating‐current machinery. Nikola Tesla had 700 patents in the United States and Europe that covered every aspect of science and technology. Tesla's discoveries include the Tesla coil, AC electrical conduction, improved lighting, newer forms of turbine engines, robotics, fluorescent light, wireless transmission of electrical energy, radio, remote control, discovery of cosmic radio waves, and the use of the ionosphere for scientific purposes. He was a genius whose discoveries had a pivotal role in advancing us into the modern era. J. Magn. Reson. Imaging 2004;19:369–374. © 2004 Wiley‐Liss, Inc.
Automated image registration of gated cardiac single‐photon emission computed tomography and magnetic resonance imaging
Authors: Aladl Usaf E. , Hurwitz Gilbert A. , Dey Damini , Levin David , Drangova Maria , Slomka Piotr J. 
Published: February 2004

AbstractPurposeTo develop an automatic registration method for electrocardiogram‐gated myocardial perfusion single‐photon emission computed tomography (SPECT) and cardiac cine‐magnetic resonance imaging (MRI).Materials and MethodsPaired myocardial perfusion SPECT (MPS) and MRI from 20 patients were considered. MR images were presegmented by heart localization based on detection of cardiac motion and optimal thresholding. A registration algorithm based on mutual information was subsequently applied to all time frames or a selected subset from both modalities.ResultsA preprocessing step significantly improved the accuracy of the registration when compared to automatic registration performed without preprocessing. Errors in translation parameters (Tx, Ty, Tz) averaged (1.0 ± 1.5, 1.1 ± 1.3, 0.9 ± 0.9) pixels with MRI segmentation and (4.6 ± 3.2, 3.4 ± 2.6, 3.0 ± 3.4) pixels without MRI segmentation. Errors in rotation parameters (Rx, Ry, Rz) averaged (5.4 ± 2.9, 3.4 ± 2.7, 4.5 ± 3.6) degrees with MRI segmentation and (9.3 ± 6.1, 4.8 ± 4.3, 14.6 ± 12.6) degrees without MRI segmentation. Error was calculated as the absolute difference between the expert manual and the automatic registration transformation.ConclusionAutomatic registration of gated MPS and cine MRI is possible with the use of a mutual information‐based technique when MR images are presegmented. Cardiac motion can be used to isolate the left ventricle (LV) on the MR images automatically, and subsequently the segmented MR images can be coregistered with gated MPS. J. Magn. Reson. Imaging 2004;19:283–290. © 2004 Wiley‐Liss, Inc.
Silicone‐specific imaging using an inversion‐recovery‐prepared fast three‐point Dixon technique
Authors: Ma Jingfei , Choi Haesun , Stafford R. Jason , Miller Michael J. 
Published: February 2004

AbstractPurposeTo demonstrate a new hybrid magnetic resonance imaging (MRI) technique capable of simultaneously generating water‐specific and silicone‐specific images in a single acquisition.Materials and MethodsThis technique combines short TI inversion‐recovery (STIR) technique for robust fat suppression with an efficient fast spin‐echo‐based three‐point Dixon technique for robust separation of remaining water and silicone in the presence of field inhomogeneities. Images demonstrating the feasibility of the technique were acquired with a 1.5‐Tesla scanner in a phantom and in a volunteer with both saline and silicone implants in vivo.ResultsThe new technique provided water‐specific and silicone‐specific images of diagnostic quality. Separation of the water and silicone chemical species was complete and satisfactory. Compared with a chemical shift‐selective technique, the new technique does not rely heavily on field homogeneity and requires the same or even less scan time to acquire images with similar scan parameters, resolution, and signal‐to‐noise ratio (SNR).ConclusionThe feasibility and potential application of the new technique were demonstrated via imaging a phantom and a silicone breast prosthesis in vivo, and it may be used for more consistent imaging of the silicone implants without compromising the image quality or overall scan time. J. Magn. Reson. Imaging 2004;19:298–302. © 2004 Wiley‐Liss, Inc.
Effect of gender on in vivo cartilage magnetic resonance imaging T2 mapping
Authors: Mosher Timothy J. , Collins Christopher M. , Smith Harvey E. , Moser Lauren E. , Sivarajah Rebecca T. , Dardzinski Bernard J. , Smith Michael B. 
Published: February 2004

AbstractPurposeTo determine if gender is a significant variable for in vivo magnetic resonance imaging (MRI) T2‐mapping of knee articular cartilage in young asymptomatic volunteers.Materials and MethodsCartilage MRI T2 mapping was performed in a young healthy population consisting of seven male and 10 female volunteers, 22 to 29 years of age. High‐resolution in vivo T2 maps were obtained of patellar, tibial, and weight‐bearing femoral articular cartilage. Spatial dependency of cartilage T2 between groups was evaluated through a comparison of cartilage T2 as a function of normalized distance from bone.ResultsBulk cartilage T2 values were similar at all three anatomic sites, and between male and female volunteers. All volunteers demonstrated similar spatial variation in cartilage MRI T2 values, with a minimum located in the radial zone and increasing T2 values toward the articular surface. There was no difference in spatial dependency of cartilage T2 between males and females.ConclusionIn young, healthy volunteers, the magnitude and spatial dependency of cartilage T2 does not differ with gender. J. Magn. Reson. Imaging 2004;19:323–328. © 2004 Wiley‐Liss, Inc.
Structural characterization of glycoporphyrins by electrospray tandem mass spectrometry
Authors: Domingues M. R. M. , Domingues P. , Reis A. , Ferrer Correia A. J. , Tomé J. P. C. , Tomé A. C. , Neves M. G. P. M. S. , Cavaleiro J. A. S. 
Published: February 2004

AbstractPorphyrin derivatives having a galactose or a bis(isopropylidene)galactose structural unit, linked by ester or ether bonds, were characterized by electrospray tandem mass spectrometry (ES‐MS/MS). The electrospray mass spectra of these glycoporphyrins show the corresponding [M + H]+ ions. For the glycoporphyrins with pyridyl substituents and those having a tetrafluorophenyl spacer, the doubly charged ions [M + 2H]2+ were also observed in ES‐MS with high relative abundance. The fragmentation of both [M + H]+ and [M + 2H]2+ ions exhibited common fragmentation pathways for porphyrins with the same sugar residue, independently of the porphyrin structural unit and type of linkage. ES‐MS/MS of the [M + H]+ ions of the galactose‐substituted porphyrins gave the fragment ions [M + H − C2H4O2]+, [M + H − C3H6O3]+, [M + H − C4H8O4]+ and [M + H − galactose residue]+. The fragmentation of the [M + 2H]2+ ions of the porphyrins with galactose shows the common doubly charged fragment ions [porphyrin + H]2+, [M + 2H − C2H4O2]2+, [M + 2H − C4H8O4]2+, [M + 2H − galactose residue]2+ and the singly charged fragment ions [M + H − C3H6O3]+ and [M + H − galactose residue]+. The fragmentation of the [M + H]+ ions of glycoporphyrins with a protected galactosyl residue leads mainly to the ions [M + H − CO(CH3)2]+, [M + H − 2CO(CH3)2]+, [M + H − 2CO(CH3)2 − CO]+, [M + H − C10H16O4]+ and [M + H − protected galactose]+. The doubly charged ions [M + 2H]2+ fragment to give the doubly charged ions [porphyrin + H]2+ and the singly charged ions [M + H − protected galactose residue]+ and [M + H − CO(CH3)2]+. For the porphyrins where the sugar structural unit is linked by an ester bond, [M + 2H]2+, ES‐MS/MS showed a major and typical fragmentation corresponding to combined loss of a sugar structural unit and further loss of water, leading to the ion [M + 2H − sugar residue − H2O]2+, independently of the structure of the sugar structural unit. These results show that ES‐MS/MS can be a powerful tool for the characterization of the sugar structural unit of glycoporphyrins, without the need for chemical hydrolysis. Copyright © 2004 John Wiley & Sons, Ltd.
De novo sequencing of antimicrobial peptides isolated from the venom glands of the wolf spider Lycosa singoriensis
Authors: Budnik B. A. , Olsen J. V. , Egorov T. A. , Anisimova V. E. , Galkina T. G. , Musolyamov A. K. , Grishin E. V. , Zubarev R. A. 
Published: February 2004

AbstractAntimicrobial peptides (AMPs), named lycocitin 1, 2 and 3, and a peptide with a monoisotopic molecular mass of 3038.70 Da were detected in the venom glands of the wolf spider Lycosa singoriensis. Two of the peptides, lycocitin 1 and 2, are new AMPs whereas lycocitin 3 is highly homologous to lycotoxin II isolated from the venom of spider Lycosa carolinensis. In addition, two other peptides with monoisotopic masses of 2034.20 and 2340.28 Da showing the motif typical for antimicrobial peptides were also identified. These peptides and lycocitin 1, 2 and 3 were de novo sequenced using electron capture dissociation and low‐energy collisional tandem mass spectrometry. The amino acid sequence of lycocitin 1 was determined as GKLQAFLAKMKEIAAQTL‐NH2. Lycocitin 2 differs from lycocitin 1 by a replacement of a lysine residue for an arginine residue at the second position. Lycocitin 3 differs from the known lycotoxin II consisting of 27 amino acid residues by a deletion of Gly‐26. Both lycocitin 1 and 2 inhibit growth of Gram‐positive (Staphylococcus aureus, Bacillus subtilis) and Gram‐negative (Escherichia coli) bacteria and fungi (Candida albicans, Pseudomonas aeruginosa) at micromolar concentrations. Copyright © 2004 John Wiley & Sons, Ltd.
Acid‐labile surfactant improves in‐sodium dodecyl sulfate polyacrylamide gel protein digestion for matrix‐assisted laser desorption/ionization mass spectrometric peptide mapping
Authors: Nomura Eiko , Katsuta Kazuhiro , Ueda Tomoko , Toriyama Michinori , Mori Tatsuya , Inagaki Naoyuki 
Published: February 2004

AbstractMass spectrometry (MS) together with genome database searches serves as a powerful tool for the identification of proteins. In proteome analysis, mixtures of cellular proteins are usually separated by sodium dodecyl sulfate (SDS) polyacrylamide gel‐based two‐dimensional gel electrophoresis (2‐DE) or one‐dimensional gel electrophoresis (1‐DE), and in‐gel digested by a specific protease. In‐gel protein digestion is one of the critical steps for sensitive protein identification by these procedures. Efficient protein digestion is required for obtaining peptide peaks necessary for protein identification by MS. This paper reports a remarkable improvement of protein digestion in SDS polyacrylamide gels using an acid‐labile surfactant, sodium 3‐[(2‐methyl‐2‐undecyl‐1,3‐dioxolan‐4‐yl)methoxy]‐1‐propanesulfonate (ALS). Pretreatment of gel pieces containing protein spots separated by 2‐DE with a small amount of ALS prior to trypsin digestion led to increases in the digested peptides eluted from the gels. Consistently, treatment of gel pieces containing silver‐stained standard proteins and those separated from tissue extracts resulted in the detection of increased numbers of peptide peaks in spectra obtained by matrix‐assisted laser desorption/ionization time of flight mass spectrometry (MALDI‐TOFMS). Hence the present protocol with ALS provides a useful strategy for sensitive protein identification by MS. Copyright © 2004 John Wiley & Sons, Ltd.
Interference of the electrospray voltage on chromatographic separations using porous graphitic carbon columns
Authors: Törnkvist Anna , Nilsson Stefan , Amirkhani Ardeshir , Nyholm Lena M. , Nyholm Leif 
Published: February 2004

AbstractThe electrospray ionization (ESI) voltage is shown to interfere with liquid chromatographic separations performed with packed porous graphitic carbon (PGC) capillary columns. This interference is ascribed to the presence of an electric field over the conductive column in the absence of an earth point between the column and the ESI emitter. The current evolved alters the chromatographic behavior of the catecholamine metabolite 3‐O‐methyl‐DOPA significantly, as both peak splitting and a dramatic decrease in the retention time were observed. Furthermore, the response from the mass spectrometer was decreased by 33% at the same time. A related compound, tyrosine, exhibited decreased retention times but no peak splitting, whereas no shifts in the retention times (or peak splitting) were seen for the less retained dopamine and noradrenaline. When the current through the PGC column was eliminated by the use of an earth point between the column and the ESI emitter, the chromatographic behavior of the column was found to return slowly to normal after hours of equilibration with 60 : 40 (v/v) methanol–ammonium formate buffer of pH 2.9. The behavior of the PGC column with and without the earth point was found to be highly reproducible during a period of 1 month. We propose that the effect of the ESI voltage on the chromatographic behavior of the PGC column is due to associated redox reactions affecting both the PGC particles and the analytes. It is concluded that (for analytical reasons), care should be taken to ensure that no current is flowing through the chromatographic system when interfacing PGC columns, and conducting parts in general, to ESI mass spectrometry. Copyright © 2004 John Wiley & Sons, Ltd.
Charge inversion mass spectrometry: dissociation of resonantly neutralized molecules
Authors: Hayakawa Shigeo 
Published: February 2004

AbstractCharge inversion mass spectrometry is an MS/MS method in which the electric charge of the precursor ions is opposite to that of the secondary product ions. Charge inversion mass spectrometry is classified into four types depending on the electric charge and time scale of collisions. Charge inversion mass spectrometry using collisions with gaseous targets in the keV energy collision range has provided insights into the structures and reactions of ions and neutral molecules. The characteristics of charge inversion experiments are presented in terms of the reaction endothermicities and the cross sections and their dependence on the target species. In the case of rare‐gas or simple molecular targets, double‐electron transfer in one collision is effective to form positive ions from negative ions, while, in the case of alkali metal targets, successive single‐electron transfers in two collisions is effective to form negative ions from positive ions. On the basis of the observed target‐density dependence of the product ion intensity and thermochemical considerations for internal energy distribution using thermometer molecules, the charge inversion processes using alkali metal targets have been confirmed to occur by electron transfers in successive collisions and the dissociation processes are found to occur in energy‐selected neutral species formed from near‐resonant neutralization with alkali metal targets. While collisionally activated dissociation (CAD) is due to dissociation of activated ions with broad internal energy distributions, the charge inversion process using alkali metal targets is due to dissociation of energy‐selected neutral species with narrow internal energy distributions. The charge inversion/alkali metal spectra provide clear differentiation of the isomeric cations of C2H2, C3H4and dichlorobenzenes. The CAD spectra of these isomeric cations are similar. Copyright © 2004 John Wiley & Sons, Ltd.
Evaluation of dissipation within an ILGA for computational electromagnetics
Authors: Treurniet J. , Simons N. R. S. , Bridges G. E. , Cuhaci M. 
Published: February 2004

AbstractInteger lattice gas automata (ILGA) are a method capable of electromagnetic field simulation that are suited to implementation on massively parallel computing architectures. The algorithm exhibits dispersion and dissipation and the purpose of this paper is to quantify the dissipation. A proposed model for the algorithm is based on a linear combination of transmission line matrix scattering and streaming operations. The dispersion relation for this model is derived and a numerical search of the dispersion relation is performed to quantify the dissipation of the model. Both the derived mathematical model and the results of numerical simulation indicate the dissipation observed fits the general form of viscosity. The isotropy of both square and hexagonal lattices are investigated. Copyright © 2004 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.
An adaptive remeshing technique based on hierarchical error estimates for simulation of semiconductor devices
Authors: Yang Geng , Wang Ruchuan , Wang Shaodi 
Published: February 2004

AbstractWe discuss first hierarchical error estimates and a criterion for mesh refinement. Then we describe briefly the hydrodynamic model of semiconductor model. Based on artificial viscosity technique about electron velocity, we propose to solve a Poisson equation to obtain a correction about mesh optimization. Finally, we simulate a GaAs MESFET's device with a gate of 0.3 µm length and give some discussions about numerical results. Copyright © 2004 John Wiley & Sons, Ltd.
A model for abrupt double heterojunction bipolar transistors
Authors: J. García‐Loureiro Antonio , M. López‐González Juan 
Published: February 2004

AbstractIn this paper, we present a model for double heterojunction bipolar transistors (DHBTs) that takes into account Fermi–Dirac statistics as well as an arbitrary injection level. The most commonly used models in the literature for heterojunction bipolar transistors (HBTs), bipolar junction transistors (BJTs) and PN junctions can be easily obtained as a particular case of the general model presented here. In order to illustrate its features, the model is applied to an InP/GaAsSb/InP DHBT and an InP/InGaAs HBT. Copyright © 2004 John Wiley & Sons, Ltd.
In vitro studies of pigment epithelium‐derived factor in human Schwann cells after treatment with axolemma‐enriched fraction
Authors: Lertsburapa Terakeith , De Vries George H. 
Published: February 2004

AbstractPigment epithelium‐derived factor (PEDF) is a multifunctional protein with known anti‐angiogenic and trophic properties, capable of promoting the survival and growth of Schwann cells (SC). Normal rat SCs and ganglioneuroma‐derived human SCs secrete PEDF. The ability of normal SC to secrete a number of trophic factors is controlled by axonal contact. Normal human Schwann cells (HSC) and malignant peripheral nerve sheath tumors (MPNST) cell lines synthesize and secrete PEDF as determined by reverse transcription PCR analysis for PEDF mRNA, immunocytochemistry, and Western blot analysis for PEDF protein. Two MPNST cell lines secreted higher levels of PEDF than did HSC. A 90.3% decrease in PEDF mRNA and a 29.3% decrease in secreted PEDF were observed after treatment of HSC with axolemma‐enriched fraction (AEF, 100 μg/ml), a neuronal membrane fraction of the axonal plasma membrane used with cultured SC to mimic axonal contact in vitro. PEDF levels remained unchanged, however, in MPNST‐derived SC conditioned media under the same treatment paradigm. These results suggest that MPNST SC lose the ability to downregulate PEDF upon axonal contact, which is characteristic of HSC. The elevated PEDF levels expressed by MPNST cell lines may serve to promote their proliferation and survival. © 2004 Wiley‐Liss, Inc.
Membrane‐associated estrogen receptor and caveolin‐1 are present in central nervous system myelin and oligodendrocyte plasma membranes
Authors: Arvanitis Dina N. , Wang Huimin , Bagshaw Richard D. , Callahan John W. , Boggs Joan M. 
Published: February 2004

AbstractThe estrogen receptor (ER) is a member of a superfamily of ligand‐regulated transcription factors that were thought to localize primarily to the nucleus; however, a membrane‐associated ER that can initiate rapid non‐genomic cell‐signaling events has been identified recently in various cells. The presence of the ER in myelin has not been reported although the nuclear form has been detected in oligodendrocytes. We have shown that an ER with similarities to ERβ is present in isolated central nervous system (CNS) myelin, the myelin sheath in spinal cord and brain sections, and the oligodendrocyte plasma membrane using two‐dimensional (2D) PAGE, mass spectrometry, peptide mass fingerprinting, Western blotting of 1D and 2D gels, and confocal microscopy. Caveolin‐1 was also shown to be present in isolated CNS myelin and oligodendrocyte plasma membranes, where it was partially colocalized with ER. After Triton X‐100 extraction of myelin, the ER was present in an insoluble low‐density glycosphingolipid‐enriched fraction and even more in a higher density fraction also containing caveolin and cytoskeletal elements, suggesting that the membrane form of ER may be associated with caveolin or the radial component of myelin. The discovery of the ER in the oligodendrocyte plasma membrane and within the myelin sheath indicates a potential role for estrogen in myelin maintenance or functions. © 2004 Wiley‐Liss, Inc.