bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biofluiddynamics of lubricating bacteria
Authors: Cohen I. , Golding I. , Ron I. G. , Ben‐Jacob E. 
Published: September 2002

AbstractVarious bacterial strains exhibit colonial branching patterns during growth on thin poor substrates. The growth can be either diffusion‐limited or kinetic‐limited, according to the imposed growth conditions. We present experimental observations of patterns exhibited by the bacterial strains Paenibacillus dendritiformis and Paenibacillus vortex. All manners of branching patterns are observed, the three main being: (1) basic branching; (2) chiral branching; (3) vortex branching. We show that the following biological features can explain the spectrum of observed patterns: (1) Formation of a lubricating fluid. (2) Food chemotactic. (3) Attractive and repulsive chemotactic signaling. (4) Flagella handedness. (5) Transition into pre‐spore state. In the theoretical studies we employ knowledge drawn from branching patterning in non‐living systems and the mathematical properties of reaction–diffusion models and atomistic models. The above can be used not just to describe existing biological understanding, but also to derive new understanding. For example, reaction–diffusion models that include bacterial density and nutrient concentration, can exhibit branching dynamics if the growth term is a meta‐stable fixed point or if the diffusion is state dependent. We show that biologically the growth term has to be an unstable fixed point, but that state‐dependent diffusion can represent the lubrication fluid excreted by the bacteria. Copyright © 2001 John Wiley & Sons, Ltd.
Microbiological fluid mechanics: a tribute to Sir James Lighthill
Authors: Blake John R. 
Published: September 2002

AbstractThe choice of title of this presentation comes from two papers that James Lighthill published in the issue of Journal of Engineering Mathematics commemorating H. A. Lorentz's famous 1896 paper on fluid mechanics [1]. This paper will discuss Lighthill's significant contribution to microbiologicalfluid mechanics, both through his own work and his postgraduate and postdoctoral students, of whichthis author is one! The paper introduces the wide range of interests that Lighthill had in biofluid‐dynamics and then moves to concentrate on contributions to microbiological fluid mechanics. Thepresentation successively considers eukaryotic flagellar propulsion, prokaryotic flagellar propulsion, filter feeding and ciliary propulsion. In the Spirit of Lighthill, the paper concludes with a list of topicsof research in the area that have been identified for further study. Copyright © 2001 John Wiley &Sons, Ltd.
One‐dimensional approximations of the eigenvalue problem of curved rods
Authors: Tambača Josip 
Published: September 2002

AbstractIn this work we analyse the asymptotic behaviour of eigenvalues and eigenfunctions of the linearized elasticity eigenvalue problem of curved rod‐like bodies with respect to the small thickness ϵ of the rod. We show that the eigenfunctions and scaled eigenvalues converge, as ϵ tends to zero, toward eigenpairs of the eigenvalue problem associated to the one‐dimensional curved rod model which is posed on the middle curve of the rod. Because of the auxiliary function appearing in the model, describing the rotation angle of the cross‐sections, the limit eigenvalue problem is non‐classical. This problem is transformed into a classical eigenvalue problem with eigenfunctions being inextensible displacements, but the corresponding linear operator is not a differential operator. Copyright © 2001 John Wiley & Sons, Ltd.
Outcome of acute lymphoblastic leukemia in children with AL90 regimen: Impact of response to treatment and sex difference on prognostic factors
Authors: Ishii Eiichi , Eguchi Haruhiko , Matsuzaki Akinobu , Koga Hiroyuki , Yanai Fumio , Kuroda Hiroshi , Kawakami Kiyoshi , Ayukawa Hiroshi , Akiyoshi Kensuke , Kamizono Junji , Tamai Yuji , Kinukawa Naoko , Okamura Jun 
Published: September 2002

AbstractBackgroundIn our previous studies, the outcome of high‐risk ALL was still poor. In the present study, all children with ALL were classified into three groups and treated with a new regimen (AL90).Patients and MethodsBetween 1990 and 1996, 220 children with ALL, treated with the AL90 regimen, were classified into three risk groups: low, intermediate, and high: LR, IR, and HR, respectively. The protocol consisted of three‐ to five‐drug induction, consolidation with intermediate‐dose methotrexate and/or cytarabine, mercaptopurine and cyclophosphamide, four‐drug intensification, and sequential maintenance therapies. Only intrathecal chemotherapy was used for CNS prophylaris in the LR group, whereas cranial irradiation was added for the IR and HR groups.ResultsThe number of eligible patients was 91: LR group, 71: IR group, and 58: HR group. Complete remission (CR) was obtained in > 98% of the LR and IR groups, while only 88% achieved CR in the HR group. The 5‐year event‐free survival (EFS) rate was 67.4% in all patients: 70.4% in the LR group, 71.7% in the IR group, and 57.5% in the HR group. With respect to the previous study, EFS in the HR group who showed positive residual leukemia at 14 days was improved, whereas EFS in boys versus girls was significantly lower (48.8% : 85.7%, P = 0.02).ConclusionsIn high‐risk ALL, the rate of induction failure was high and boys had a worse outcome, calling for improvements in induction therapy and a specific approach for boys. Med. Pediatr. Oncol. 37:10–19, 2001. © 2001 Wiley‐Liss, Inc.
Clean adiabatic TOCSYs
Authors: Kupče Ē. , Hiller W. 
Published: September 2002

AbstractVarious adiabatic mixing schemes are explored using numerical simulations with the aim of finding suitable mixing sequences for fast rotating samples with relatively wide resonances and poorly resolved J‐couplings, such as proteins or resin‐bound products of solid‐phase synthesis. It is shown both experimentally and by simulations that WURST‐2 mixing scheme provides the best sensitivity and the lowest interference from cross‐relaxation effects in the spin diffusion limit. For medium‐sized molecules, WURST‐1, constant adiabaticity Gaussian and hyperbolic secant are the possible alternatives. Copyright © 2001 John Wiley & Sons, Ltd.
Determination of solution conformation of allergenically active pentasaccharitol obtained from sea squirt antigen
Authors: Kato Yuko , Ohta Masaya , Munakata Tatsuo , Fujiwara Masako , Fujii Naoyuki , Shigeta Seiko , Matsuura Fumito 
Published: September 2002

AbstractPentasaccharitol, GalNAcβ1–4(GalNAcα1–2Fucα1–3)GlcNAcβ1–3GalNAc‐ol, termed HPG‐β2‐N5a, is an allergenically active O‐linked oligosaccharitol derived from a sea squirt H‐antigen. Concerning the interaction between the allergen and specific IgE, an analysis of the solution conformation of the saccharitol was carried out. 1H and 13C NMR assignments for the pentasaccharitol were obtained using 1D‐HOHAHA, TOCSY, DEPT135, HSQC and HMBC techniques. The solution conformation was determined using a combination of 2D‐NMR ROESY data and distance geometry (DG) calculations in dihedral angle space with the DADAS 90 program. Two conformers, family A (FamA) and family B (FamB), that satisfied almost all the NOE constraints were obtained, and supplemental MD calculations revealed that FamA was in conformational equilibrium whereas FamB was rather flexible. The molecule of HPG‐β2‐N5a had a layered and not a linear conformation. Copyright © 2001 John Wiley & Sons, Ltd.
Fast measurement of heteronuclear relaxation: frequency‐domain analysis of NMR accordion spectroscopy
Authors: Rabier Patricia , Kieffer Bruno , Koehl Patrice , Lefèvre Jean‐François 
Published: September 2002

AbstractNMR relaxation parameters are usually derived from series of 2D experiments. The whole procedure can be very time consuming, especially for the study of the relaxation of nuclei at natural abundance. Palmer and Mandel have proposed the use of accordion spectroscopy to determine one relaxation parameter using two experiments only. In this paper, we show that the experimental time can be further reduced, by recording only three experiments for the determination of both the longitudinal and transverse relaxation rates. The analysis of the experiments is performed in the frequency domain, the relaxation rates being deduced from the linewidth of the peaks of interest. A detailed statistical analysis of errors introduced by the line fitting procedure on derived relaxation parameters was used to derive guidelines for the choice of experimental parameters. This procedure was applied to the study of the Cα relaxation parameters of a six‐residue unlabeled peptide. The results were compared with those obtained by classical accordion spectroscopy. Copyright © 2001 John Wiley & Sons, Ltd.
Deuterium isotope effects on 13C NMR chemical shifts of some α‐(2‐hydroxyaryl)‐N‐phenylnitrones (Schiff base N‐oxides)
Authors: Dziembowska T. , Rozwadowski Z. , Majewski E. , Ambroziak K. 
Published: September 2002

AbstractThe deuterium isotope effect on the 13C NMR chemical shifts of some α‐2‐hydroxyaryl‐N‐phenylnitrones (Schiff base N‐oxides) was studied. The existence of an intramolecular hydrogen bond with the proton localized on the phenolic oxygen atom was evidenced. Exceptionally large isotope effects ΔC‐2(D) and ΔC‐α(D) suggest that the substitution of the proton of the OH group by deuterium leads to a weakening of the hydrogen bond and some conformational changes in the molecule. This conclusion was drawn on the basis of a comparison of the deuterium isotope effects of Schiff base N‐oxides and parent Schiff bases. Copyright © 2001 John Wiley & Sons, Ltd.
Primary structure and developmental expression of Dp ZP2, a vitelline envelope glycoprotein homolog of mouse ZP2, in Discoglossus pictus, one of the oldest living Anuran species
Authors: Vaccaro M.C. , Santo M.G. De , Caputo M. , Just M. , Tian J.D. , Gong H. , Lennarz W.J. , Campanella C. 
Published: September 2002

AbstractA glycoprotein of the Xenopus vitelline envelope, gp 69/64, which mediates sperm binding, is closely related to the components of ZPA family, such as the mouse zona pellucida ZP2. To test the generality of these findings, we studied Discoglossus pictus, a species evolutionary distant from Xenopus and identified as a protein of 63 kDa in the vitelline envelope. Preliminary studies suggest that this protein may bind sperm at fertilization. We found that the 63‐kDa protein is glycosylated and contains both N‐ and O‐linked chains. We have cloned the cDNA encoding the Discoglossus protein of 63 kDa (Dp ZP2) by screening a Discoglossus cDNA library using Xenopus gp 69/64 cDNA as a probe. Analysis of the deduced sequence of Discoglossus protein revealed 48% identity with Xenopus gp 69/64 and 37–40% identity with mouse ZP2. The sequence conservation included a ZP domain, a potential furin cleavage site and a putative transmembrane domain. The N‐terminus region of Dp ZP2 was 40% identical to the corresponding region of Xenopus gp 69/64 which has been shown to be essential for sperm binding to the VE. Although, as of yet, there is no evidence for sperm binding at the Dp ZP2 N‐terminus, it is interesting that in this region three potential O‐glycosylation sites are conserved in both species, in contrast to N‐glycosylation sites. It was found that the Dp ZP2 mRNA is expressed in stage 1 oocytes and in the follicle cells surrounding the oocyte. Similarly, in Xenopus oocytes, the gp 69/64m RNA, was found in the oocytes, as well as in the somatic cells. Mol. Reprod. Dev. 59:133–143, 2001. © 2001 Wiley‐Liss, Inc.
Germinal vesicle materials are not required for the activation of MAP kinase in porcine oocyte maturation
Authors: Sugiura K. , Naito K. , Iwamori N. , Kagii H. , Goto S. , Ohashi S. , Yamanouchi K. , Tojo H. 
Published: September 2002

AbstractThe requirement of the germinal vesicle (GV) for the normal kinetics of mitogen‐activated protein (MAP) kinase activity during porcine oocyte maturation was investigated. Porcine follicular oocytes were enucleated, and the locations of their extracellular signal‐regulated kinases 1 and 2 (ERK1/2), major MAP kinases in maturating porcine oocytes, were detected by indirect immunofluorescent microscopy. The MAP kinase activity was assayed as myelin basic protein (MBP) kinase activity, and the phosphorylation states of ERK1/2 were detected by immunoblotting analyses. Translocation of MAP kinase into the GV and association with the spindle were observed in intact oocytes, while MAP kinase in enucleated oocytes was distributed almost uniformly in cytoplasm throughout the culturing period. The phosphorylation and the activation of MAP kinase were induced, and the activity was comparable with that of control denuded oocytes. The high level of activity was maintained through maturation, even in the absence of spindle formation. These results indicate that the presence of nuclear material and translocation into the GV are dispensable for the activation of MAP kinase and that associating with the spindle is not required for maintenance of its activity though porcine oocyte maturation. Mol. Reprod. Dev. 59:215–220, 2001. © 2001 Wiley‐Liss, Inc.
Porcine oocyte activation: Differing roles of calcium and pH
Authors: Ruddock Nancy T. , Macháty Zoltán , Cabot Ryan A. , Prather Randall S. 
Published: September 2002

AbstractIntracellular pH has recently been shown to increase during parthenogenetic activation of the porcine oocyte. In the following set of experiments, intracellular pH was monitored during activation and pronuclear development was assessed following activation treatments with calcium, in the absence of calcium, and in oocytes loaded with the calcium chelator BAPTA‐AM in calcium‐free medium. Intracellular pH increase was not different among groups when treating with 7% ethanol or 50 μM calcium ionophore, or during treatment with thimerosal for 12 or 25 min. Activation with thimerosal (200 μM, 12 min) followed by 8 mM dithiothreitol (DTT, 30 min) resulted in a decreased pronuclear development in calcium‐free medium with or without BAPTA‐AM loaded oocytes as compared to controls. Activation with 50 μM calcium ionophore resulted in pronuclear development that was different between the calcium‐free and BAPTA‐AM loaded oocytes in calcium‐free medium. Similar incidences of pronuclear formation were observed in all ethanol treatment groups. It was concluded that external calcium as well as large changes in intracellular free calcium are not necessary for the increase in intracellular pH, but normal intracellular calcium signaling is critical for normal levels of pronuclear development. Finally, oocytes were measured for intracellular pH changes for 30 min following subzonal sperm injection. Intracellular pH did not increase, although pronuclear formation was observed 6 hr post SUZI. This suggested that major differences were still present between sperm‐induced and parthenogenetic activation of the porcine oocyte. Mol. Reprod. Dev. 59:227–234, 2001. © 2001 Wiley‐Liss, Inc.
Multishot diffusion‐weighted FSE using PROPELLER MRI
Authors: Pipe James G. , Farthing Victoria G. , Forbes Kirsten P. 
Published: September 2002

AbstractA method for obtaining diffusion‐weighted images that are free from the artifacts associated with echo‐planar acquisitions, such as signal pile‐up and geometric warping, is introduced. It uses an ungated, multishot fast spin‐echo (FSE) acquisition that is self‐navigated. The phase of the refocusing pulses is alternated to minimize non‐Carr‐Purcell‐Meiboom‐Gill (CPMG) artifacts. Several reconstruction methods are combined to make this method robust against motion artifacts. Examples are shown of clinical diffusion‐weighted imaging and high‐resolution diffusion tensor imaging. Magn Reson Med 47:42–52, 2002. © 2002 Wiley‐Liss, Inc.
Intracellular acidification and volume increases explain R2 decreases in exercising muscle
Authors: Damon Bruce M. , Gregory Carl D. , Hall Kristen L. , Stark Heather J. , Gulani Vikas , Dawson M. Joan 
Published: September 2002

AbstractExercise‐induced decreases in the 1H transverse relaxation rate (R2) of muscle have been well documented, but the mechanism remains unclear. In this study, the hypothesis was tested that R2 decreases could be explained by pH decreases and apparent intracellular volume (Vi′) increases. 31P and 1H spectroscopy, biexponential R2 analysis, and imaging were performed prior to and following fatiguing exercise in iodoacetate‐treated (IAA, to inhibit glycolysis), NaCN‐treated (to inhibit oxidative phosphorylation), and untreated frog gastrocnemii. In all exercised muscles, the apparent intracellular R2 (R2i′) and pH decreased, while intracellular osmolytes and Vi′ increased. These effects were larger in NaCN‐treated and untreated muscles than in IAA‐treated muscles. Multiple regression analysis showed that pH and Vi′ changes explain 70% of the R2i′ variance. Separate experiments in unexercised muscles demonstrated causal relationships between pH and R2i′ and between Vi′ and R2i′. These data indicate that the R2 change of exercise is primarily an intracellular phenomenon caused by the accumulation of the end‐products of anaerobic metabolism. In the NaCN‐treated and untreated muscles, the R2i′ change increased as field strength increased, suggesting a role for pH‐modulated chemical exchange. Magn Reson Med 47:14–23, 2002. © 2002 Wiley‐Liss, Inc.
CPMG measurements and ultrafast imaging in human lungs with hyperpolarized helium‐3 at low field (0.1 T)
Authors: Durand E. , Guillot G. , Darrasse L. , Tastevin G. , Nacher P.J. , Vignaud A. , Vattolo D. , Bittoun J. 
Published: September 2002

AbstractThis work reports the use of single‐shot spin echo sequences to achieve in vivo diffusion gas measurements and ultrafast imaging of human lungs, in vivo, with hyperpolarized3He at 0.1 T. The observed transverse relaxation time of3He lasted up to 10 s, which made it possible to use long Carr‐Purcell‐Meiboom‐Gill echo trains. Preliminary NMR studies showed that the resolution of lung images acquired with hyperpolarized3He and single‐shot sequences is limited to about 6 mm because of the diffusion of the gas in applied field gradients. Ultrafast images of human lungs in normal subjects, achieved in less than 0.4 s with the equivalent of only 130 μmol of fully polarized3He, are presented. Comparison with other studies shows that there is no SNR penalty by using low fields in the hyperpolarized case. Advantage was taken of the self diffusion‐weighting of the rapid acquisition with relaxation enhancement (RARE) sequence to acquire apparent diffusion coefficient (ADC) images of the lungs. Time scales of seconds could be explored for the first time because there is no hindrance fromTas with the usual approaches. At 0.1 T, 180° RF pulses can be repeated every 10 ms without exceeding specific absorption rate limits, which would not be the case for higher fields. Moreover, at low field, susceptibility‐induced phenomena are expected to be milder. This supports the idea that low‐field imagers can be used for hyperpolarized noble gas MRI of lungs and may be preferred for ADC measurements. Magn Reson Med 47:75–81, 2002. © 2002 Wiley‐Liss, Inc.
Assessment of a rapid clearance blood pool MR contrast medium (P792) for assays of microvascular characteristics in experimental breast tumors with correlations to histopathology
Authors: Turetschek Karl , Floyd Eugenia , Shames David M. , Roberts Timothy P.L. , Preda Anda , Novikov Viktor , Corot Claire , Carter Wayne O. , Brasch Robert C. 
Published: September 2002

AbstractThe diagnostic potential of a new rapid clearance blood pool contrast medium (P792; MW = 6.47 kDa) for the MR assessment of microvessel characteristics was assessed in 42 chemically‐induced breast tumors, with comparisons to albumin‐(Gd‐DTPA). Microvessel characteristics, including the transendothelial permeability (KPS) and the fractional blood volume (fPV), were estimated by using dynamic MR data fit to a bidirectional two‐compartment model. The MR‐derived estimates for KPS and fPV using each contrast agent were compared, and assays using each contrast agent were correlated to the histologic tumor grade (SBR score) and the microvascular density (MVD) counts. Using P792‐enhanced data, neither KPS nor fPV showed a statistically significant correlation with the tumor grade or the MVD (P > .05). Conversely, using albumin‐(GdDTPA)30, KPS values correlated significantly with the histologic tumor grade (r = .55; P < .0005) and the MVD (r = .34, P < .05), whereas no correlation was established for fPV. In conclusion, based on P792 data no correlation between tumor microvascular characteristics and histologic markers (SBR score or MVD) was found in this breast tumor model. Our analysis suggests that contrast media of relatively large (on the order of 90 kDa) molecular size, such as albumin‐(GdDTPA)30, are more accurate for the characterization of tumor microvessels. Magn Reson Med 45:880–886, 2001. © 2001 Wiley‐Liss, Inc.
Simple linear formulation for magnetostimulation specific to MRI gradient coils
Authors: Chronik Blaine A. , Rutt Brian K. 
Published: September 2002

AbstractA simple linear formulation for magnetostimulation thresholds specific to MRI gradient coils is derived based on established hyperbolic electrostimulation strength vs. duration relations. Thresholds are derived in terms of the gradient excursion required to cause stimulation, and it is demonstrated that the threshold curve is a linear function of the gradient switching time. A parameter β is introduced as being fundamental in the evaluation of gradient coil stimulation. β is a map of the induced electric field per unit gradient slew rate, and can be calculated directly from the gradient coil wire pattern. Consideration of β alone is sufficient to compare stimulation thresholds between different gradient coil designs, as well as to evaluate the expected dependency of stimulation threshold on position within the gradient coil. The linear gradient threshold curve is characterized by two parameters: SRmin and ΔGmin. SRmin is the slope of the threshold curve and represents the minimum slew rate required to cause stimulation in the limit of infinite gradient strength. ΔGmin is the vertical axis intercept of the curve and represents the minimum gradient excursion required to cause stimulation in the limit of infinite slew rate. Both SRmin and ΔGmin are functions of both β and the standard tissue parameters Er (rheobase) and τc (chronaxie time). The ease with which both the gradient system performance and the stimulation thresholds can be plotted on the same axes is noted and is used to introduce the concept of a piece‐wise linear operational limit curve for a gradient system. Magn Reson Med 45:916–919, 2001. © 2001 Wiley‐Liss, Inc.