bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serotonin patterns locomotor network activity in the developing zebrafish by modulating quiescent periods
Authors: Brustein Edna , Chong Mabel , Holmqvist Bo , Drapeau Pierre 
Published: November 2003

AbstractDeveloping neural networks follow common trends such as expression of spontaneous, recurring activity patterns, and appearance of neuromodulation. How these processes integrate to yield mature, behaviorally relevant activity patterns is largely unknown. We examined the integration of serotonergic neuromodulation and its role in the functional organization of the accessible locomotor network in developing zebrafish at behavioral and cellular levels. Locally restricted populations of serotonergic neurons and their projections appeared in the hindbrain and spinal cord of larvae after hatching (≈day 2). However, 5‐HT affected the swimming pattern only from day 4 on, when sustained spontaneous swimming appeared. 5‐HT and its agonist quipazine increased motor output by reducing intervals of inactivity, observed behaviorally (by high‐speed video) and in recordings from spinal neurons during fictive swimming (by whole‐cell current clamp). 5‐HT and quipazine had little effect on the properties of the activity periods, such as the duration of swim episodes and swim frequency. Further, neuronal input resistance, rheobasic current, and resting potential were not affected significantly. The 5‐HT antagonists methysergide and ketanserin decreased motor output by prolonging the periods of inactivity with little effect on the active swim episode or neuronal properties. Our results suggest that 5‐HT neuromodulation is integrated early in development of the locomotor network to increase its output by reducing periods of inactivity with little effect on the activity periods, which in contrast are the main targets of 5‐HT neuromodulation in neonatal and adult preparations. © 2003 Wiley Periodicals, Inc. J Neurobiol 57: 303–322, 2003
Vestibular Schwann cells are a distinct subpopulation of peripheral glia with specific sensitivity to growth factors and extracellular matrix components
Authors: Bartolami Sylvain , Augé Christelle , Travo Cécile , Ventéo Stéphanie , Knipper Marlies , Sans Alain 
Published: November 2003

AbstractVestibular nerve Schwann cells are predisposed to develop schwannoma. While knowledge concerning this condition has greatly improved, little is known about properties of normal vestibular Schwann cells. In an attempt to understand this predisposition, we evaluated cell density regulation and proliferative features of these cells taken from 6‐day‐old rats. Data were compared to those obtained with sciatic Schwann cells. In both vestibular and sciatic 7‐day‐old cultures, Schwann cells appear as bipolar or flattened cells. However, sciatic and vestibular cells greatly differ in other aspects: on poly‐L‐lysine coating, sciatic cells specifically synthesize myelin basic protein, while expression of P0 mRNAs is restricted to some vestibular cells. Laminin increases sciatic cell density but not that of vestibular cells. Fibronectin selectively enhances the proliferation of vestibular Schwann cells and lacks an effect on sciatic ones. Comparison of cell density changes between sciatic and vestibular cells shows that they are sensitive to two different sets of growth factors. Progesterone and FGF‐2 combined with forskolin selectively enhance the cell density of sciatic glia, while IGF‐1 and GDNF specifically increase vestibular cell density. Furthermore, BrdU incorporation assays indicate that GDNF is also a mitogen for vestibular cells. Altogether, vestibular Schwann cells display phenotypic features and responsiveness to exogenous signals that are significantly different from sciatic Schwann cells, suggesting that vestibular glia form a subpopulation of Schwann cells. © 2003 Wiley Periodicals, Inc. J Neurobiol 57: 270–290, 2003
B‐type Eph receptors and ephrins induce growth cone collapse through distinct intracellular pathways
Authors: Mann Fanny , Miranda Elena , Weinl Christine , Harmer Emma , Holt Christine E. 
Published: November 2003

AbstractForward and reverse signaling mediated by EphB tyrosine kinase receptors and their transmembrane ephrin‐B ligands play important roles in axon pathfinding, yet little is known about the intracellular pathways involved. Here we have used growth cones from the ventral (EphB receptor‐bearing) and dorsal (ephrin‐B‐bearing) embryonic Xenopus retina to investigate the signaling mechanisms in both forward and reverse directions. We report that unclustered, but not clustered, EphB2 ectodomains trigger fast (5–10 min) transient collapse responses in growth cones. This collapse response is mediated by low levels of intracellular cyclic GMP and requires proteasome function. In contrast, clustered, but not unclustered, ephrin‐B1 ectodomains cause slow (30–60 min) growth cone collapse that depends on high cGMP levels and is insensitive to inhibition of the proteasomal pathway. Upon receptor‐ligand binding, endocytosis occurs in the reverse direction (EphB2‐Fc into dorsal retinal growth cones), but not the forward direction, and is also sensitive to proteasomal inhibition. Endocytosis is functionally important because blocking of EphB2 internalization inhibits growth cone collapse. Our data reveal that distinct signaling mechanisms exist for B‐type Eph/ephrin‐mediated growth cone guidance and suggest that endocytosis provides a fast mechanism for switching off signaling in the reverse direction. © 2003 Wiley Periodicals, Inc. J Neurobiol 57: 323–336, 2003
Cisco Systems puts its HR programs and processes on line and reaps big productivity gains
Authors: Wittman Brit 
Published: November 2003

AbstractAs the leading provider of Internet networking technology, Cisco Systems practices what it preaches. It has
relentlessly sought ways to use its own intranet to communicate instantly and consistently with its 34,000 worldwide
employees, to enable managers to conduct most HR transactions on line, and to allow employees to update and access
an array of employment and benefits information. Cisco's on‐line HR and communications tools have
produced impressive productivity gains, but as importantly, they are an invaluable means for reinforcing a common
culture and unifying a globally dispersed workforce. © 2003 Cisco Systems, Inc.
The aging workforce raises new talent management issues for employers
Authors: Rappaport Anna , Bancroft Ed , Okum Lauren 
Published: November 2003

AbstractWith Baby Boomers aging and fewer thirty‐somethings in the employment ranks, the graying of the
workforce is right around the corner. With it will come a host of issues—loss of human capital, talent
shortages, ageism, and culture clash among them—that will force employers to rethink many of their
practices for acquiring and managing talent. Employers can take specific steps now to cushion the impact of the
aging of their workforce, and those who act too late may find themselves at a competitive disadvantage.
© 2003 Wiley Periodicals, Inc.
Orientation of platelets in multilayered nanocomposite polymer films
Authors: Malwitz Matthew M. , Lin‐Gibson Sheng , Hobbie Erik K. , Butler Paul D. , Schmidt Gudrun 
Published: November 2003

AbstractThe orientation of platelets in micro‐meter‐thick polymer‐clay nanocomposite films was investigated with small‐angle neutron scattering (SANS), small‐angle X‐ray scattering (SAXS), and wide‐angle X‐ray diffraction (WAXD). The films with various clay contents (15–60% by mass fraction) were prepared by a layer‐by‐layer approach from polymer‐clay solutions that led to the formation of a high degree of orientation in both polymer and clay platelets. Shear‐induced orientation of polymer‐clay solutions is compared with the orientation of polymer‐clay films. SANS, SAXS, and WAXD, with beam configurations in and perpendicular to the spread direction of the film, were used to determine the structure and orientation of platelets. In all films, the clay platelets oriented preferentially in the plane of the film. The observed differences in semidilute solutions, with clay surface normal parallel to the vorticity direction, versus bulk films and with clay surface normal parallel to the shear gradient direction at clay mass fractions of 40 and 60%, were attributed to the collapses of clay platelet during the drying process. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3237–3248, 2003
Long‐lived excitons up to 1 μs in GaN/AlN self‐assembled quantum dots
Authors: Kako S. , Miyamura M. , Hoshino K. , Arakawa Y. 
Published: November 2003

AbstractWe report the observation of long‐lived excitons in GaN/AlN self‐assembled quantum dots at the temperature of 3.5 K. The PL decay time strongly increases and reaches μs order with increasing size of the QDs. This strongly suggests that the PL decay is almost free from non‐radiative processes and dominated by radiative recombination processes in the GaN QDs. The increase of the PL decay time with increasing size of the QDs originates from the reduction of the oscillator strength due to the strong built‐in electric field in the GaN/AlN heterostructures. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of ketotifen and its conjugated metabolite in human plasma by liquid chromatography/tandem mass spectrometry: application to a pharmacokinetic study
Authors: Chen Xiaoyan , Zhong Dafang , Liu Dan , Wang Yingwu , Han Ying , Gu Jingkai 
Published: November 2003

AbstractA sensitive and specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed for the investigation of the pharmacokinetics of ketotifen and its major metabolite, ketotifen N‐glucuronide, in human plasma. The plasma samples were treated by liquid–liquid extraction and analyzed using LC/MS/MS with an electrospray ionization interface. Diphenhydramine was used as the internal standard. The method had a lower limit of quantitation of 10 pg/mL for ketotifen, which offered increased sensitivity, selectivity and speed of analysis, compared with existing methods. The intra‐ and inter‐day precision were measured to be below 8.2% and accuracy between −2.4% and 3.4% for all QC samples. Incubation of the plasma samples with β‐glucuronidase allowed the quantitation of ketotifen N‐glucuronide. This quantitation method was successfully applied to a pharmacokinetic study of ketotifen and its major metabolite after oral administration of 2 mg ketotifen fumarate to 16 healthy volunteers. Copyright © 2003 John Wiley & Sons, Ltd.
Characterization of ammonium chloride derivatives by salt clustering in electrospray mass spectrometry
Authors: Charles Laurence , Chiron Julien , Galy Jean‐Pierre 
Published: November 2003

AbstractClustering of ammonium chloride salts was studied using an electrospray source to characterize the form, mono‐ vs. dihydrochloride, of organic compounds by mass spectrometry. This new way of taking advantage of cluster formation is applied to aminomethylacridines as their storage requires the synthesis of such derivatives. Both positive and negative cluster mass spectra were obtained and allowed the determination of the nature of the hydrochloride forms as the salt mass is straightforwardly derived from the mass of the cluster monomer, calculated from singly and multiply charged ion distributions. The identity of the counterion is confirmed from the mass of the ionic moieties in the clusters. Copyright © 2003 John Wiley & Sons, Ltd.
Electrospray mass spectrometric investigation of the binding of cis‐parinaric acid to bovine beta‐lactoglobulin and study of the ligand‐binding site of the protein using limited proteolysis
Authors: Imre Tímea , Zsila Ferenc , Szabó Pál T. 
Published: November 2003

AbstractThe binding property of parinaric acid, a polyunsaturated fatty acid, to bovine β‐lactoglobulin, has been studied by electrospray ionization mass spectrometry. Stable complexation was observed under acidic conditions in a molar ratio of 1:1. Competitive complexation experiments were performed using saturated and unsaturated fatty acid standards with different chain lengths and number of double bonds to study the specificity of the interaction. It can be concluded that formation of the parinaric acid–lactoglobulin complex is preferred even if the molar concentration of the other fatty acids is ten times higher. In cases of specific complex formation the protein must have an active site that is a good acceptor for the ligand molecule. Limited trypsinolysis was performed on the lactoglobulin molecule to identify which part is responsible for the complexation. An intermediate tryptic fragment with molecular mass of 5200 Da was found to have the same ability to bind parinaric acid as the intact protein. This disulfide‐bonded residue, [41‐70]S‐S[149‐162], might thus be involved in the specific complexation of parinaric acid to β‐lactoglobulin. This conclusion is consistent with previous information on this binding site. Copyright © 2003 John Wiley & Sons, Ltd.
Electron ionization mass spectrometry of citrus limonoids
Authors: Tian Qingguo , Li Dan , Barbacci Damon , Schwartz Steven J. , Patil Bhimanagouda S. 
Published: November 2003

AbstractElectron ionization (EI) mass spectrometry was used to differentiate four structurally closely related citrus limonoid aglycones, including limonin, nomilin, obacunone, and deacetylnomilin. The limonoids were isolated and purified from citrus seeds. Structures of major fragment ions were elucidated by high‐resolution mass spectrometry (HRMS) and fragmentation pathways were proposed. The fragmentation patterns observed in the EI spectra can be used as important references for the positive characterization of limonoid aglycones. Copyright © 2003 John Wiley & Sons, Ltd.
Two new organic reference materials for δ13C and δ15N measurements and a new value for the δ13C of NBS 22 oil
Authors: Qi Haiping , Coplen Tyler B. , Geilmann Heike , Brand Willi A. , Böhlke J. K. 
Published: November 2003

AbstractAnalytical grade L‐glutamic acid is chemically stable and has a C/N mole ratio of 5, which is close to that of many of natural biological materials, such as blood and animal tissue. Two L‐glutamic acid reference materials with substantially different 13C and 15N abundances have been prepared for use as organic reference materials for C and N isotopic measurements. USGS40 is analytical grade L‐glutamic acid and has a δ13C value of −26.24‰ relative to VPDB and a δ15N value of −4.52‰ relative to N2 in air. USGS41 was prepared by dissolving analytical grade L‐glutamic acid with L‐glutamic acid enriched in 13C and 15N. USGS41 has a δ13C value of +37.76‰ and a δ15N value of +47.57‰. The δ13C and δ15N values of both materials were measured against the international reference materials NBS 19 calcium carbonate (δ13C = +1.95‰), L‐SVEC lithium carbonate (δ13C = −46.48‰), IAEA‐N‐1 ammonium sulfate (δ15N = 0.43‰), and USGS32 potassium nitrate (δ15N = 180‰) by on‐line combustion continuous‐flow and off‐line dual‐inlet isotope‐ratio mass spectrometry. Both USGS40 and USGS41 are isotopically homogeneous; reproducibility of δ13C is better than 0.13‰, and that of δ15N is better than 0.13‰ in 100‐μg amounts. These two isotopic reference materials can be used for (i) calibrating local laboratory reference materials, and (ii) quantifying drift with time, mass‐dependent fractionations, and isotope‐ratio‐scale contraction in the isotopic analysis of various biological materials. Isotopic results presented in this paper yield a δ13C value for NBS 22 oil of −29.91‰, in contrast to the commonly accepted value of −29.78‰ for which off‐line blank corrections probably have not been quantified satisfactorily. Published in 2003 by John Wiley & Sons, Ltd.
A direct injection high‐throughput liquid chromatography tandem mass spectrometry method for the determination of a new orally active αvβ3 antagonist in human urine and dialysate
Authors: Zeng Wei , Wang Amy Qiu , Fisher Alison L. , Musson Donald G. 
Published: November 2003

AbstractA generic high‐throughput liquid chromatography (HTLC) tandem mass spectrometry (MS/MS) assay for the determination of compound I in human urine and dialysate (hemodialysis) was developed and validated. By using the HTLC on‐line extraction technique, sample pretreatment was not necessary. The sample was directly injected onto a narrow bore large particle size extraction column (50 × 1.0 mm, 60 μm) where the sample matrix was rapidly washed away using a high flow rate (5 mL/min) aqueous mobile phase while analytes were retained. The analytes were subsequently eluted from the extraction column onto an analytical column using an organic‐enriched mobile phase prior to mass spectrometric detection. The analytes were then eluted from the analytical column to the mass spectrometer for the determination. The linear dynamic range was 2.0–6000 ng/mL for the urine assay and 0.1–300 ng/mL for the dialysate assay. Intraday accuracy and precision were evaluated by analyzing five replicates of calibration standards at all concentrations used to construct the standard curve. For the urine assay, the precision (RSD%, n = 5) ranged from 1.9 to 8.0% and the accuracy ranged from 87.8 to 105.2% of nominal value. For the dialysate assay, the precision (RSD%, n = 5) ranged from 1.1 to 10.0% and the accuracy from 94.5 to 105.2% of nominal value. In‐source fragmentation of the acyl glucuronide metabolite (compound III) did not interfere with the determination of parent compound I. The developed HTLC/MS/MS methodology was specific for compound I in the presence of compound III. Column life‐time is increased and sample analysis time is decreased over traditional reversed‐phase methods when direct injection assays for urine and dialysate are coupled with the technology of HTLC. Copyright © 2003 John Wiley & Sons, Ltd.
Gas chromatography/mass spectrometry for the characterization of organic materials in frescoes of the Momumental Cemetery of Pisa (Italy)
Authors: Bonaduce Ilaria , Colombini Maria Perla 
Published: November 2003

AbstractThe paper deals with the application of two analytical procedures, based respectively on on‐line pyrolysis in the presence of hexamethyldisilazane followed by gas chromatography/mass spectrometric analysis (Py/GC/MS) and on selective extractions and microwave‐assisted hydrolysis followed by GC/MS determination. These procedures give reliable data on the organic composition of micro‐samples; moreover, when applied to the same micro‐sample, they give comparable data on natural substances, and complementary information on synthetic compounds and degradation products. The two methods were used to characterise the organic matter present in several samples taken from scenes of the frescoes ‘Giudizio Universale’ and the ‘Ascensione’ by Bonamico Buffalmacco in the Monumental Cemetery of Pisa. The observed hydrophobicity of their surfaces, which hampers traditional means of restoration, is explained by the formation of a polymeric network due to reactions between a synthetic polymer used as adhesive, the proteinaceous material (animal glue and casein), and formaldehyde. Copyright © 2003 John Wiley & Sons, Ltd.
Dual isotope and isotopomer ratios of N2O emitted from a temperate grassland soil after fertiliser application
Authors: Bol R. , Toyoda S. , Yamulki S. , Hawkins J. M. B. , Cardenas L. M. , Yoshida N. 
Published: November 2003

AbstractThe N2O and N2 fluxes emitted from a temperate UK grassland soil after fertiliser application (equivalent to 25 and 75 kg N ha−1) were simultaneously measured, using a new automated soil incubation system, which replaces soil atmosphere (N2 dominated) with a He+O2 mixture. Dual isotope and isotopomer ratios of the emitted N2O were also determined. Total N2O and N2 fluxes were significantly lower (P < 0.001) in the control (0 kg N) than in the 25 and 75 kg N treatments. The total N2O flux was significantly higher (P < 0.001) in the 75 kg N than in the 25 kg N treatment. The general patterns of N2O and N2 fluxes were similar for both fertiliser treatments. The total gaseous N loss in the control treatment was nearly all N2, whereas in the fertiliser treatment more N2O than N2 was emitted from the soil. The ratio N2O/N2 fluxes as measured during the experiment suggested three phases in N2O production, in phase 1 nitrification > denitrification, in phase 2 denitrification > nitrification, and in phase 3 denitrification (and total denitrification) ≫ nitrification. Dual δ15N and δ18O isotope and isotopomer (δ15Nα and δ15Nβ) value ratios of emitted N2O also pointed towards an increasing dominance of the production of N2O by denitrification and total denitrification. The site preference value from the soil‐emitted N2O was lower than the troposphere value. This confirmed that the enhanced troposphere N2O site preference could result from back injection of N2O from the stratosphere. The measurements of N2O/N2 flux ratio and the isotopic content of emitted N2O pointed, independently, to similar temporal trends in N2O production processes after fertiliser application to grassland soil. This confirmed that both measurements are suitable diagnostic tools to study the N2O production process in soils. Copyright © 2003 John Wiley & Sons, Ltd.
The fragmentations of [M–H]− anions derived from underivatised peptides. The side‐chain loss of H2S from Cys. A joint experimental and theoretical study
Authors: Bilusich Daniel , Brinkworth Craig S. , McAnoy Andrew M. , Bowie John H. 
Published: November 2003

AbstractLoss of H2S is the characteristic Cys side‐chain fragmentation of the [MH]− anions of Cys‐containing peptides. A combination of experiment and theory suggests that this reaction is initiated from the Cys enolate anion as follows: RNH‐−C(CH2SH)CONHR′ Ø [RNHC(CH2)CONHR′ (HS−)] Ø [RNHC(CH2)CO‐HNR′‐H]−+H2S. This process is facile. Calculations at the HF/6‐31G(d)//AM1 level of theory indicate that the initial anion needs only ≥20.1 kcal mol−1 of excess energy to effect loss of H2S. Loss of CH2S is a minor process, RNHCH(CH2SH)CON−‐R′ Ø RNHCH(CH2S−)CONHR′ Ø RNH −CHCONHR+CH2S, requiring an excess energy of ≥50.2 kcal mol−1. When Cys occupies the C‐terminal end of a peptide, the major fragmentation from the [M–H]− species involves loss of (H2S+CO2). A deuterium‐labelling study suggests that this could either be a charge‐remote reaction (a process which occurs remote from and uninfluenced by the charged centre in the molecule), or an anionic reaction initiated from the C‐terminal CO2− group. These processes have barriers requiring the starting material to have an excess energy of ≥79.6 (charge‐remote) or ≥67.1 (anion‐directed) kcal mol−1, respectively, at the HF/6‐31G(d)//AM1 level of theory. The corresponding losses of CH2O and H2O from the [MH]− anions of Ser‐containing peptides require ≥35.6 and ≥44.4 kcal mol−1 of excess energy (calculated at the AM1 level of theory), explaining why loss of CH2O is the characteristic side‐chain loss of Ser in the negative ion mode. Copyright © 2003 John Wiley & Sons, Ltd.