bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Drosophila fruitless‐gal4 transgenes reveals expression in male‐specific fruitless neurons and innervation of male reproductive structures
Authors: Billeter Jean‐Christophe , Goodwin Stephen F. 
Published: June 2004

AbstractThe fruitless (fru) gene acts in the central nervous system (CNS) of Drosophila melanogaster to establish male sexual behavior. Genetic dissection of the locus has shown that one of the fru gene's promoter, P1, controls the spatial and temporal expression of male‐specific FruM proteins critical to determining stereotypical male sexual behavior. By using the Gal4‐expression system, we show that a 16‐kb fragment of the fru P1 promoter's 5′ regulatory region drives the expression of Gal4 in a subset of FruM‐expressing neurons within both the pupal and adult CNS. Colocalization of FruM and a Gal4‐responsive reporter shows that the fru(P1)‐gal4 fusion construct generates expression in both previously characterized FruM‐expressing neurons as well as within cells of both the CNS and the peripheral nervous system that have not been demonstrated as FruM‐expressing. Gal4‐expressing neurons are shown to innervate abdominal organs directly relevant to fru function; specifically, the muscle of Lawrence (MOL) and the male internal reproductive organs. Innervations of the latter are shown to originate from identified FruM‐serotonergic neurons. Furthermore, we show that the MOL neuromuscular junction is sexually dimorphic. Finally, we describe Gal4 expression in neurites innervating male reproductive structures that are hypothesized to be targets of fru function. Isolation of the regulatory sequences controlling the expression of fru in the CNS, therefore, provides a potent tool for the manipulation of FruM‐expressing neurons and for understanding the cellular basis of Drosophila reproductive behavior. J. Comp. Neurol. 475:270–287, 2004. © 2004 Wiley‐Liss, Inc.
On the regularity of flows with Ladyzhenskaya Shear‐dependent viscosity and slip or non‐slip boundary conditions
Authors: Beirão da Veiga H. 
Published: June 2004

AbstractNavier‐Stokes equations with shear dependent viscosity under the classical non‐slip boundary condition have been introduced and studied, in the sixties, by O. A. Ladyzhenskaya and, in the case of gradient dependent viscosity, by J.‐L. Lions. A particular case is the well known Smagorinsky turbulence model. This is nowadays a central subject of investigation. On the other hand, boundary conditions of slip type seems to be more realistic in some situations, in particular in numerical applications. They are a main research subject. The existence of weak solutions u to the above problems, with slip (or non‐slip) type boundary conditions, is well known in many cases. However, regularity up to the boundary still presents many open questions. In what follows we present some regularity results, in the stationary case, for weak solutions to this kind of problems; see Theorems 3.1 and 3.2. The evolution problem is studied in the forthcoming paper [6]; see the remark at the end of the introduction. © 2004 Wiley Periodicals, Inc.
Approach to self‐similarity in Smoluchowski's coagulation equations
Authors: Menon Govind , Pego Robert L. 
Published: June 2004

AbstractWe consider the approach to self‐similarity (or dynamical scaling) in Smoluchowski's equations of coagulation for the solvable kernels K(x, y) = 2, x + y and xy. In addition to the known self‐similar solutions with exponential tails, there are one‐parameter families of solutions with algebraic decay, whose form is related to heavy‐tailed distributions well‐known in probability theory. For K = 2 the size distribution is Mittag‐Leffler, and for K = x + y and K = xy it is a power‐law rescaling of a maximally skewed α‐stable Lévy distribution. We characterize completely the domains of attraction of all self‐similar solutions under weak convergence of measures. Our results are analogous to the classical characterization of stable distributions in probability theory. The proofs are simple, relying on the Laplace transform and a fundamental rigidity lemma for scaling limits. © 2003 Wiley Periodicals, Inc.
Determination of Chemical Shift Anisotropy Tensors of Carbonyl Nuclei in Proteins through Cross‐Correlated Relaxation in NMR
Authors: Cisnetti Federico , Loth Karine , Pelupessy Philippe , Bodenhausen Geoffrey 
Published: June 2004

AbstractThe principal components and orientations of the chemical shift anisotropy (CSA) tensors of nearly all 13C carbonyl nuclei in a small protein have been determined in isotropic solution by a combination of three complementary cross‐correlation measurements.
Approximate Solutions of the Bloch–McConnell Equations for Two‐Site Chemical Exchange
Authors: Abergel Daniel , Palmer Arthur G. 
Published: June 2004

AbstractApproximate formulas for the transverse‐relaxation rate constant and resonance frequency have been derived for nuclear spins subject to two‐site chemical exchange. The new results are more accurate than previous approximations when chemical exchange does not approach the fast‐exchange limit or when site populations are not highly asymmetric. Results are derived from an effective average evolution operator that contains contributions from both exact eigenvalues of the Bloch–McConnell equations. These expressions are useful for interpretation of chemical exchange processes in NMR spectroscopy.
Rotor Modulations and Recoupling Strategies in 13C Solid‐State Magic‐Angle‐Spinning NMR Spectroscopy: Probing Molecular Orientation and Dynamics
Authors: Fischbach Ingrid , Ebert Florian , Spiess Hans Wolfgang , Schnell Ingo 
Published: June 2004

AbstractRecoupling strategies for anisotropic interactions enable the investigation of molecular structure, order and dynamics in a sensitive and site‐specific fashion by solid‐state NMR spectroscopy. Whereas magic‐angle spinning (MAS) efficiently averages anisotropic interactions and enhances spectral resolution, recoupling pulse sequences selectively restore certain parts of rotor‐modulated dipole–dipole couplings or chemical shift anisotropies (CSA). More specifically, it is possible to recouple either the ωR‐ or the 2ωR‐modulated terms of an interaction Hamiltonian, which exhibit different orientation dependencies and, in this way, provide a means of distinguishing whether the observed NMR spectra are affected by molecular motion or by molecular orientation. Sideband patterns generated by reconversion rotor encoding allow for a precise and selective determination of coupling constants and anisotropies, which contain site‐specific information on structure, orientation and/or dynamics of individual molecular segments. Corresponding recoupling schemes are presented in a common context, and the possibilities of exploiting these effects for the determination of order parameters of oriented materials, such as oriented polymer chains or extruded fibres of a discotic mesogen, are discussed. The obtained orientational order parameters are compared to results from two‐dimensional wide angle X‐ray scattering (WAXS).
Backbone‐Only Protein Solution Structures with a Combination of Classical and Paramagnetism‐Based Constraints: A Method that Can Be Scaled to Large Molecules
Authors: Barbieri Renato , Luchinat Claudio , Parigi Giacomo 
Published: June 2004

AbstractHerein, it is shown that a medium‐resolution solution structure of a protein can be obtained with the sole assignment of the protein backbone and backbone‐related constraints if a derivative with a firmly bound paramagnetic metal is available. The proof‐of‐concept is provided on calbindin D9k, a calcium binding protein in which one of the two calcium ions can be selectively substituted by a paramagnetic lanthanide ion. The constraints used are HN (and Hα) nuclear Overhauser effects (NOEs), hydrogen bonds, dihedral angle constraints from chemical shifts, and the following paramagnetism‐based constraints: 1) pseudocontact shifts, acquired by substituting one (or more) lanthanide(s) in the C‐terminal calcium binding site; 2) NHN residual dipolar couplings due to self‐orientation induced by the paramagnetic lanthanide(s); 3) cross‐correlations between the Curie and internuclear dipole–dipole interactions; and 4) paramagnetism‐induced relaxation rate enhancements. An upper distance limit for internuclear distances between any two backbone atoms was also given according to the molecular weight of the protein. For this purpose, the paramagnetism‐based constraints were collectively implemented in the program CYANA for solution structure determinations, similarly to what was previously done for the program DYANA. The method is intrinsically suitable for large molecular weight proteins.
Spectral Deconvolution of Chemical Mixtures by Covariance NMR
Authors: Zhang Fengli , Brüschweiler Rafael 
Published: June 2004

AbstractA method is presented for the deconvolution of the NMR spectrum of a chemical mixture without requiring physical separation of its components. The method, which is termed “Demix”, is based on a principal component analysis of a series of one‐dimensional (1D) spectra that are statistically modulated during preparation and TOCSY mixing periods. The largest principal components correspond to the 1D NMR spectra of the scalar J‐coupled spin networks of the individual components of the mixture. The method is demonstrated for aqueous mixtures of the amino acids Glu, Leu, Lys, and Val.
Polarization‐Transfer Methods in Solid‐State Magic‐Angle‐Spinning NMR: Adiabatic CN Pulse Sequences
Authors: Verel René , Meier Beat H. 
Published: June 2004

AbstractAn adiabatic double‐quantum polarization‐transfer experiment is described. It can be characterized as an adiabatic variant of the POST‐C7 experiment. A continuous variation of the phase increment between pulses leads to the introduction of a fictitious Zeeman field that allows for an adiabatic passage through the recoupling condition. This results in a chemical‐shift‐offset‐compensated adiabatic experiment, which leads to an efficient and broadbanded polarization transfer or to a double‐quantum excitation. Similar variations of other C‐ or R‐type experiments can be envisioned.
Polymer Dynamics under Nanoscopic Constraints: The “Corset Effect” as Revealed by NMR Relaxometry and Diffusometry
Authors: Fatkullin Nail , Fischer Elmar , Mattea Carlos , Beginn Uwe , Kimmich Rainer 
Published: June 2004

AbstractA spinodal demixing technique was employed for the preparation of linear poly(ethylene oxide) (PEO) confined in nanoscopic strands, which in turn are embedded in a quasi‐solid methacrylate matrix impenetrable to PEO. Both the molecular weight of the PEO and the mean diameter of the strands are variable to a certain degree. Chain dynamics of the PEO in the molten state were examined with the aid of field‐gradient NMR diffusometry and field‐cycling NMR relaxometry. The dominating mechanism for translational displacements in the nanoscopic strands is shown to be reptation. A formalism for the evaluation of NMR diffusometry is presented, which permits the estimation of the mean PEO strand diameter. Samples of different composition revealed diameters in the range 9–58 nm, in reasonable agreement with electron micrographs. The time scale of the diffusion measurements was 10–300 ms. On the much shorter time scale of field‐cycling NMR relaxometry, 10−9–10−4 s, a frequency dispersion of the spin‐lattice relaxation time characteristic for reptation clearly showed up in all samples. An effective tube diameter of only 0.6 nm was found even when the strand diameter was larger than the radius of gyration of the PEO chain random coils. The finding that the tube diameter effective on the short time scale of field‐cycling NMR relaxometry is much smaller than the diameter of the confining structure is termed the “corset effect”, and is traced back to the lack of local free‐volume fluctuation capacity under nanoscale confinements. The order of magnitude of the “pore” diameter, at which the cross‐over from confined to bulk chain dynamics is expected, is estimated.
Sensitivity Enhancement in Two‐Dimensional Solid‐State NMR Spectroscopy by Transverse Mixing
Authors: Tycko Robert 
Published: June 2004

AbstractThe sensitivity of two‐dimensional (2D) 13C–13C solid‐state NMR spectroscopy under magic‐angle spinning (MAS) is shown to be enhanced by the use of transverse polarization transfer in place of the conventional longitudinal polarization transfer. Experimental results are reported for 2D spectroscopy of a 20‐residue, filament‐forming peptide derived from the E. coli RecA protein, containing five uniformly 13C‐labeled residues, performed at 14.1 T with high‐speed MAS and with finite‐pulse radio‐frequency‐driven recoupling of dipolar interactions in the mixing period. Significant sensitivity enhancements observed at short mixing periods result from a more rapid build‐up of cross‐peaks under transverse mixing than under longitudinal mixing and from the ${\sqrt{2}}$ gain inherent in 2D measurements in which both orthogonal transverse polarization components in the t1 period contribute to each free‐induction decay signal detected in the t2 period.
Sensitivity Enhancement in 1D Heteronuclear NMR Spectroscopy via Single‐Scan Inverse Experiments
Authors: Mishkovsky Mor , Frydman Lucio 
Published: June 2004

AbstractMeasuring the nuclear magnetic resonance spectra of low‐γ heteronuclei such as 15N constitutes an important analytical tool for the characterization of molecular structure and dynamics. The reduced resonance frequencies and magnetic moments of these heteronuclei, however, make the sensitivity of this kind of spectroscopy inherently lower than that of comparable 1H NMR observations. A well‐known solution to this sensitivity problem is indirect detection: a 2D NMR technique capable of enhancing the sensitivity of heteronuclear NMR by porting the actual data acquisition from the low‐γ nucleus to neighboring protons. This has become the standard method of observation in biomolecular NMR, where the resolution introduced by 2D spectroscopy is always a sought‐after commodity. Indirect detection, however, has not gained a wide appeal in organic chemistry or in in vivo investigations, where one‐dimensional heteronuclear NMR information usually suffices. The present study explores the possibility of retaining certain advantages derived from indirect detection while not giving up on the simple one‐dimensional nature of heteronuclear NMR, by relying on the spatial‐encoding scheme we have recently demonstrated for implementing single‐scan multidimensional NMR spectroscopy. Preliminary results based on a 1D modification of this experiment confirm theoretical calculations suggesting that the sensitivity of 1D 15N NMR can be enhanced significantly in this manner; the relevance of this experiment given the advent of dedicated 1H‐observing cryogenic probeheads with very high sensitivities is briefly discussed.
Confirmation of Mycobacterium tuberculosis infection by flow cytometry after ex vivo incubation of peripheral blood T cells with an ESAT‐6‐derived peptide pool
Authors: Tesfa Lydia , Koch Franz‐Wilhelm , Pankow Wulf , Volk Hans‐Dieter , Kern Florian 
Published: June 2004

AbstractBackgroundThe presence of a T‐cell response to the early secretory antigenic target‐6 (ESAT‐6) indicates previous infection with or exposure to Mycobacterium tuberculosis. Measuring this response is useful for identifying individuals infected with M. tuberculosis. It was also reported that the frequencies of ESAT‐6‐specific T cells correlate with disease state. Established procedures measure secreted T‐cell cytokines following whole blood stimulation with recombinant ESAT‐6 protein or use Elispot as a read‐out.MethodsA single ESAT‐6‐ spanning pool of overlapping peptides (15 amino acids length with 11 overlaps) was used for overnight stimulation of peripheral blood mononuclear cells (PBMCs) from 15 patients infected with Mycobacterium tuberculosis and 11 healthy controls. T‐cell responses were rated positive if interferon‐γ (IFN‐γ)‐producing T cells were identified above background level, using 4‐color cytokine flow cytometry.ResultsThirteen of 15 (87%) patients, but none of the healthy controls, had a positive CD4 T‐cell response to the ESAT‐6 spanning peptide pool. The frequencies of IFN‐γ‐producing cells varied between 1 and 167 per 10,000 CD4 T cells. The test performed as well as the tests described in the literature.ConclusionsCytokine flow cytometry following PBMC stimulation with an ESAT‐6 spanning peptide pool is a useful laboratory test for ESAT‐6‐specific T cells combining precise counting and multi‐parameter phenotyping. © 2004 Wiley‐Liss, Inc.
Tetraspan and beta‐1 integrins expression pattern of the epithelial lung adenocarcinoma cell line A549 and its sensitivity to divalent cations
Authors: Massin Frédéric , Rubinstein Eric , Faure Gilbert C. , Martinet Yves , Boucheix Claude , Béné Marie C. 
Published: June 2004

AbstractBackgroundTetraspans are ubiquitous integral transmembrane molecules associated on the cell surface with such adhesion molecules as integrins. Their expression has been shown to vary in tumors, but has seldom been described on lung tumoral epithelial cells, and the conditions required for a proper association of tetraspans and integrins have not yet been fully explored.MethodsWe investigated the expression of 10 tetraspans and six β1 integrins on the tumoral lung epithelial cell line A549. Cells were examined both in quantitative flow cytometry and as monolayers, under normal or chelated conditions, in order to determine the cation dependency of their expression.ResultsFive tetraspans and four β1 integrins are expressed on the membrane of A549 cells. Both quantitative and qualitative surface and cytoplasmic modifications of this pattern were induced in chelating conditions, suggesting the importance of divalent cations for the expression of these molecules.ConclusionsThese data indicate that a specific pattern of tetraspans and integrins, relying strongly on the availability of divalent cations in the microenvironment, is expressed by tumoral epithelial cells. © 2004 Wiley‐Liss, Inc.
MARCO expression on pediatric alveolar macrophages
Authors: Bunn Hazel J. , Kobzik Lester , Grigg Jonathan 
Published: June 2004

AbstractBackgroundPhagocytosis of unopsonized pollutant particles by alveolar macrophages (AM) occurs via the macrophage receptor with collagenous structure (MARCO). In a previous study, we demonstrated that the laser scanning cytometer (LSC) can be used to characterize receptor expression in pediatric AM. Since we have demonstrated the presence of ultrafine carbon particles within AM obtained from young infants, we sought to determine MARCO expression by pediatric AM using the LSC, hypothesizing that MARCO expression, and hence the ability to phagocytize pollutant particles, is mature in early infancy.MethodsAM from 17 healthy children undergoing elective surgery, between 0.1 and 14.1 years of age, were obtained by bronchoalveolar lavage. Cytocentrifuged AM were dual immunostained with monoclonal antibodies to the panmacrophage marker CD68, and either MARCO or an appropriate isotypic control. Expression of MARCO was quantified using LSC and adjusted for cell area. Intensity of immunostaining was compared to each child's own isotypic control.ResultsMARCO was present on 98% of pediatric AM. There was no association between age and either intensity of MARCO expression or the proportion of cells expressing MARCO.ConclusionsWe conclude that there is no developmental immaturity in the major receptor responsible for unopsonized particle uptake in healthy young children. © 2004 Wiley‐Liss, Inc.
Cytometric bead assay of cytokines in sepsis: A clinical evaluation
Authors: Vedrine Christophe , Caraion Cristina , Lambert Claude , Genin Christian 
Published: June 2004

AbstractBackgroundThe clinical relevancy of an attractive new multiparametric method, cytometric beads assay (CBA), was evaluated for the monitoring of cytokines in sepsis.MethodsA total of 52 samples (26 patients) were simultaneously tested by CBA and chemiluminescence (IL‐6, IL‐8, IL‐1β, and TNFα) or ELISA (IL‐10, IL‐12 p40, IL‐12 p70, and soluble TNFα‐RI).ResultsCBA standard curves were linear from 20–5,000 ng/L except for IL‐1β (40–5,000 ng/L). IL‐6 and IL‐8 were detected in 41 and 48 samples (44–5,000 ng/L and 22–5,000 ng/L), respectively, and out of range in six samples. IL‐10 and IL‐1β were detected in 14 and 15 samples (21–1,548 ng/L and 29–582 ng/L), respectively. TNFα was rarely detected, and IL‐12 p70 was never detected. Accuracy and repeatability were good (CV for IL‐6 was 2.1–8.7%; for IL‐8 3.7–5.3%; for IL‐10 2.5–9.1%; for IL‐12 5.2–6.5%; for IL‐1 β 4–12%; and for TNFα 3–19.3%). Reproducibility of four standard curves and 20 samples (−1.1 to +1.03%) was excellent between tests done at two‐ to six‐week intervals. CBA values were correlated (r2 > 0.89; P < 0.001) with our reference methods, but were lower on CBA (TNFα 45% ± 8; IL‐6 49% ± 7), probably due to interactions with patients' serum, as confirmed by spiking diluted standards in one patient's serum with end stage renal failure and high levels of TNF soluble receptor (i.e., TNFα levels 34 and 21%).ConclusionsFinally, these results suggest that IL‐6, IL‐8, IL‐1β, and Il‐10 are clinically promising for sepsis evaluation. However, sensitivity of TNFα has to be improved and IL‐12 p70 should be replaced with more relevant parameters such as TNF‐R, procalcitonin, or neopterin. © 2004 Wiley‐Liss, Inc.
Flow cytometric test for beryllium sensitivity
Authors: Milovanova Tatyana N. , Popma Sicco H. , Cherian Sindhu , Moore Jonni S. , Rossman Milton D. 
Published: June 2004

AbstractBackgroundChronic beryllium disease (CBD) is an occupational granulomatous disorder characterized by hypersensitivity to beryllium, mediated by CD4+ T lymphocytes, and predominantly affects the lungs. In this disorder, lymphocyte proliferative responses to beryllium, measured by 3H thymidine incorporation, are used for diagnosis of CBD, for screening asymptomatic workers or former workers to detect unrecognized disease, and for surveillance as a bioassay to detect abnormal exposures. Problems with test variability and the use of radioactivity have recently led to the search for alternative methods.MethodsWe applied a 5,6‐carboxyfluorescein diacetate succinimidyl ester flow cytometric technique for measurement of mitogen‐ and antigen‐induced T‐lymphocyte proliferation to a group of beryllium‐exposed sensitized individuals and beryllium‐unexposed controls.ResultsWe detected mitogen and antigen proliferative responses in CD3+, CD4+, and CD8+ subpopulations. Phytohemagglutinin and Candida stimulated CD4+ and CD8+ T‐cell responses, but beryllium appeared to stimulate only CD3+/CD4+ responses.ConclusionsThis technique may provide a sensitive, nonradioactive alternative to the traditional proliferation tests that measure beryllium sensitivity. It offers the added specificity of enabling phenotypic description of the responding cell type and may prove to be easier to standardize for clinical use. © 2004 Wiley‐Liss, Inc.