bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of ingestion byDrepanoptila holosericea(Columbidae) on the seed germination ofSantalum austrocaledonicum(Santalaceae)
Authors: Tassin Jacques , Barré Nicolas , Bouvet Jean-Marc
Published: March 2008

Santalum austrocaledonicumVieill. (Santalaceae) is a small tree endemic to New Caledonia and Vanuatu, well-known for the highly priced aromatic oil of its heartwood (Nasi & Ehrhart 1996). In New Caledonia, sandalwood grows on Loyalty Islands, the Isle of Pines and Grande-Terre (Bottinet al. 2006). The tree produces single-seeded fleshy drupes, which turn dark-red at maturity. Sandalwood seeds are dormant because of their hard coat and germinate only on physical scarification, or after removing the coat (Chauvin & Ehrhart 1998). In natural habitats, such seeds need further processing to relieve dormancy and promote germination, within a period where there is a good chance of successful seedling establishment (Murdoch & Ellis 2000).
Forecasting the impacts of climate variability: lessons from the rainfed corn market in Ceará, Brazil
Authors: CHIMELI ARIASTER B. , DE SOUZA FILHO FRANCISCO DE ASSIS , HOLANDA MARCOS COSTA , PETTERINI FRANCIS CARLO
Published: March 2008

A number of studies show that climatic shocks have significant economic impacts in several regions of the world, especially in, but not limited to, developing economies. In this paper we focus on a drought-related indicator of well-being and emergency spending in the Brazilian semi-arid zone – rainfed corn market – and estimate aggregate behavioral and forecast models for this market conditional on local climate determinants. We find encouraging evidence that our approach can help policy makers buy time to help them prepare for drought mitigating actions. The analysis is applicable to economies elsewhere in the world and climatic impacts other than those caused by droughts.
Lysosomal Cholesterol Accumulation Inhibits Subsequent Hydrolysis of Lipoprotein Cholesteryl Ester
Authors: Jerome W. Gray , Cox Brian E. , Griffin Evelyn E. , Ullery Jody C.
Published: March 2008

Human macrophages incubated for prolonged periods with mildly oxidized LDL (oxLDL) or cholesteryl ester-rich lipid dispersions (DISP) accumulate free and esterified cholesterol within large, swollen lysosomes similar to those in foam cells of atherosclerosis. The cholesteryl ester (CE) accumulation is, in part, the result of inhibition of lysosomal hydrolysis due to increased lysosomal pH mediated by excessive lysosomal free cholesterol (FC). To determine if the inhibition of hydrolysis was long lived and further define the extent of the lysosomal defect, we incubated THP-1 macrophages with oxLDL or DISP to produce lysosome sterol engorgement and then chased with acetylated LDL (acLDL). Unlike oxLDL or DISP, CE from acLDL normally is hydrolyzed rapidly. Three days of incubation with oxLDL or DISP produced an excess of CE in lipid-engorged lysosomes, indicative of inhibition. After prolonged oxLDL or DISP pretreatment, subsequent hydrolysis of acLDL CE was inhibited. Coincident with the inhibition, the lipid-engorged lysosomes failed to maintain an acidic pH during both the initial pretreatment and subsequent acLDL incubation. This indicates that the alterations in lysosomes were general, long lived, and affected subsequent lipoprotein metabolism. This same phenomenon, occurring within atherosclerotic foam cells, could significantly affect lesion progression.
Development and Application of an Internet Electron Microscopy System for the Outreach Program in Japan
Authors: Tanaka Miyoko , Tameike Akane , Ishikawa Nobuhiro , Furuya Kazuo
Published: March 2008

The development of a remotely operated scanning electron microscopy (SEM) system and its use by high school students and the public as an outreach program are reported. The SEM and the server are located in the National Institute for Materials Science, Tsukuba, Japan, with client computers installed at a science museum and high schools. Using a secure virtual private network system and scheduling/management groupware, observation of SEM images and energy dispersive X-ray analysis are widely and frequently performed throughout Japan.
Luminescence Database I—Minerals and Materials
Authors: MacRae Colin M. , Wilson Nicholas C.
Published: March 2008

A luminescence database for minerals and materials has been complied from the literature, the aim being to create a resource that will aid in the analysis of luminescence spectral of ionic species in minerals and materials. The database is based on a range of excitation techniques and records both major and minor lines, and their activators. The luminescence techniques included in the database are cathodoluminescence, ion luminescence, and photoluminescence. When combined with other traditional X-ray measurements collected on the same region, use of the luminescence database will give additional insight into the chemistry of minerals and materials.
Scaling properties of sea ice deformation from buoy dispersion analysis
Authors: Rampal P. , Weiss J. , Marsan D. , Lindsay R. , Stern H.
Published: March 2008

A temporal and spatial scaling analysis of Arctic sea ice deformation is performed over timescales from 3 h to 3 months and over spatial scales from 300 m to 300 km. The deformation is derived from the dispersion of pairs of drifting buoys, using the IABP (International Arctic Buoy Program) buoy data sets. This study characterizes the deformation of a very large solid plate (the Arctic sea ice cover) stressed by heterogeneous forcing terms like winds and ocean currents. It shows that the sea ice deformation rate depends on the scales of observation following specific space and time scaling laws. These scaling properties share similarities with those observed for turbulent fluids, especially for the ocean and the atmosphere. However, in our case, the time scaling exponent depends on the spatial scale, and the spatial exponent on the temporal scale, which implies a time/space coupling. An analysis of the exponent values shows that Arctic sea ice deformation is very heterogeneous and intermittent whatever the scales, i.e., it cannot be considered as viscous‐like, even at very large time and/or spatial scales. Instead, it suggests a deformation accommodated by a multiscale fracturing/faulting processes.
Sensitivity of modeled arctic mixed‐phase stratocumulus to cloud condensation and ice nuclei over regionally varying surface conditions
Authors: Morrison Hugh , Pinto James O. , Curry Judith A. , McFarquhar Greg M.
Published: March 2008

A two‐moment microphysics scheme implemented in the polar version of the mesoscale model MM5 is used to simulate a mixed‐phase stratocumulus deck observed during the Fall 2004 Mixed‐Phase Arctic Cloud Experiment (MPACE). In situ aircraft instrumentation and remote sensors gathered extensive microphysical and radiative data that serve as a testbed for the model. Model results are reasonably similar to observations in terms of the liquid microphysical properties, while the ice microphysical properties are more significantly biased, especially the ice crystal concentration. Sensitivity tests examine the impact of increased cloud condensation and ice nucleus concentrations. Increasing the concentration of cloud condensation nuclei to values typical for polluted ‘Arctic haze’ conditions substantially reduces the mean droplet size, but has little impact on the downwelling longwave flux because the cloud already emits as a blackbody (except near the Arctic Ocean pack ice edge). However, the smaller droplet size does lead to a slight increase in liquid water path and more significant decrease (∼50%) in the ice water path and snowfall rate due to reduced collision‐coalescence and riming of snow by droplets. Increasing the ice nucleus concentration specified from MPACE observations by 1–2 orders of magnitude produces a substantial reduction in liquid water path and downwelling longwave flux at the surface over interior northern Alaska, but has less impact over the open ocean and coastal regions. However, a large discrepancy between the observed ice nucleus and ice crystal concentrations, leading to the under‐prediction of simulated crystal concentration, also suggests that additional ice initiation mechanisms (not included in current models) may have occurred in the real cloud layer.
Characterization and acid‐mobilization study of iron‐containing mineral dust source materials
Authors: Cwiertny David M. , Baltrusaitis Jonas , Hunter Gordon J. , Laskin Alexander , Scherer Michelle M. , Grassian Vicki H.
Published: March 2008

Processes that solubilize iron in mineral dust aerosol may increase the amount of iron supplied to ocean surface waters, and thereby stimulate phytoplankton productivity. In particular, the uptake of acids such as H2SO4 and HNO3 on mineral dust surfaces can produce extremely acidic environments that promote iron dissolution. Here, four samples that represent source materials for mineral dust (Saudi Beach sand (SB), Inland Saudi sand (IS), Saharan Sand (SS) and China Loess (CL)) and one commercial reference material (Arizona Test Dust (AZTD)) were characterized, and examined in dissolution studies in solutions of sulfuric, nitric and hydrochloric acid ranging from pH 1 to 3. Mössbauer spectroscopy revealed Fe(III) in all samples, whereas SB, CL and AZTD also contained appreciable Fe(II). Spectra suggest that both Fe(II) and Fe(III) were substituted into aluminosilicates, although CL, AZTD and IS also contained Fe(III) oxide phases. Total iron solubility measured after 24 h ranged between 4–16% of the initial iron content for each material, but did not scale with either the specific surface area or the total iron content of the samples. Instead, we show that Fe(II)‐containing solid phases such as Fe(II)‐substituted aluminosilicates represent a significant, and sometimes dominant, source of soluble Fe in acidic environments. Results of dissolution studies also show that the nature of the acid influences iron solubilization, as elevated concentrations of nitrate encountered from nitric acid at pH 1 suppressed Fe(II) formation. We propose a surface‐mediated, non‐photochemical redox reaction between nitrate and Fe(II), which may contribute to Fe(II)/Fe(III) cycling in the atmosphere.
Antimalarial drugs inhibit human 5‐HT3and GABAAbut not GABACreceptors
Authors: Thompson A J , Lummis S C R
Published: March 2008

Background and purpose:Antimalarial compounds have been previously shown to inhibit rodent nicotinic acetylcholine (nACh) and 5‐HT3receptors. Here, we extend these studies to include human 5‐HT3A, 5‐HT3AB, GABAAα1β2, GABAAα1β2γ2 and GABACρ1 receptors.

Experimental approach:We examined the effects of quinine, chloroquine and mefloquine on the electrophysiological properties of receptors expressed inXenopusoocytes.

Key results:5‐HT3Areceptor responses were inhibited by mefloquine, quinine and chloroquine withIC50values of 0.66, 1.06 and 24.3 μM. At 5‐HT3ABreceptors, the potencies of mefloquine (IC50=2.7 μM) and quinine (15.8 μM), but not chloroquine (23.6 μM), were reduced. Mefloquine, quinine and chloroquine had higherIC50values at GABAAα1β2 (98.7, 0.40 and 0.46 mM, respectively) and GABAAα1β2γ2 receptors (0.38, 1.69 and 0.67 mM, respectively). No effect was observed at GABACρ1 receptors. At all 5‐HT3and GABAAreceptors, chloroquine displayed competitive behaviour and mefloquine was non‐competitive. Quinine was competitive at 5‐HT3Aand GABAAreceptors, but non‐competitive at 5‐HT3ABreceptors. Homology modelling in combination with automated docking suggested orientations of quinine and chloroquine at the GABAAreceptor binding site.

Conclusions and implications:The effects of mefloquine, quinine and chloroquine are distinct at GABAAand GABACreceptors, whereas their effects on 5‐HT3ABreceptors are broadly similar to those at 5‐HT3Areceptors.IC50values for chloroquine and mefloquine at 5‐HT3receptors are close to therapeutic blood concentrations required for malarial treatment, suggesting that their therapeutic use could be extended to include the treatment of 5‐HT3receptor‐related disorders.

British Journal of Pharmacology(2008)153, 1686–1696; doi:10.1038/bjp.2008.34; published online 3 March 2008
Gabapentin activates ROMK1 channels by a protein kinase A (PKA)‐dependent mechanism
Authors: Lee C‐H , Tsai T‐S , Liou H‐H
Published: March 2008

Background and purpose:Gabapentin is an effective anticonvulsant. The major physiological function of renal outer medullary potassium (ROMK1) channels is to maintain the resting membrane potential (RMP). We investigated the effect of gabapentin on ROMK1 channels and the mechanism involved.

Experimental approach:Xenopusoocytes were injected with mRNA coding for wild‐type or mutant ROMK1 channels and giant inside‐out patch‐clamp recordings were performed.

Key results:Gabapentin increased the activity of ROMK1 channels, concentration‐dependently and enhanced the activity of wild‐type and an intracellular pH (pHi)‐gating residue mutant (K80M) channels over a range of pHi. Gabapentin also increased activity of channels mutated at phosphatidylinositol 4,5‐bisphosphate (PIP2)‐binding sites (R188Q, R217A and K218A). However, gabapentin failed to enhance channel activity in the presence of protein kinase A (PKA) inhibitors and did not activate phosphorylation site mutants (S44A, S219A or S313A), mutants that mimicked the negative charge carried by a phosphate group bound to a serine (S44D, S219D or S313D), or a mutated channel with a positive charge (S219R). These findings show that gabapentin activates ROMK1 channels independently of the pHiand not via a PIP2‐dependent pathway. The effects of gabapentin on ROMK1 channels may be due to a PKA‐mediated phosphorylation‐induced conformational change, but not to charge–charge interactions.

Conclusions and implications:ROMK1 channels are the main channels responsible for maintaining the RMP during cellular excitation. Gabapentin increased the activity of ROMK1 channels by a PKA‐dependent mechanism, reducing neuronal excitability, and this may play an important role in its antiepileptic effect.
Autonomic nervous system‐dependent and ‐independent cardiovascular effects of exendin‐4 infusion in conscious rats
Authors: Gardiner S M , March J E , Kemp P A , Bennett T
Published: March 2008

Background and purpose: Glucagon‐like peptide‐1 (GLP) receptor agonists are promising therapeutic agents for the treatment of type II diabetes, but effects other than those on glucoregulation need assessing. Cardiovascular actions of bolus doses of the GLP receptor agonist exendin‐4 have been reported, but to date the effects of continuous infusions have not been described.

Experimental approach: The regional haemodynamic effects and possible underlying mechanisms of 6 h infusions of exendin‐4 were measured in conscious, chronically instrumented rats.

Key results: A 6 h infusion of exendin‐4 (up to 6 pmol kg−1 min−1) only modestly influenced blood pressure, but caused substantial, opposing, regionally selective vascular effects and tachycardia. A major involvement of β‐adrenoceptors in the vasodilator and cardiac effects was identified, with little or no direct contribution from α‐adrenoceptors to the vasoconstriction seen. Under conditions where α‐ and β‐adrenoceptors were antagonized, or when ganglionic transmission was blocked, a marked vasoconstrictor effect of exendin‐4 was revealed in the mesenteric and hindquarters vascular beds (about 50% fall in vascular conductances). No role for endogenous angiotensin II, vasopressin, endothelin, neuropeptide Y or prostanoids could be shown in these vasoconstrictor actions of exendin‐4.

Conclusions and implications: The results show not only an important involvement of the autonomic nervous system in the cardiovascular actions of exendin‐4 infusion but also an underlying non‐autonomically mediated vasoconstrictor action, the mechanism of which remains to be identified.
Development of ion injection into the BNL test electron beam ion source using a prototype low energy beam transfer switchyard and a hollow cathode ion source (abstract)
Authors: Beebe E. N. , Alessi J. G. , Kponou A. , Meitzler C. , Pikin A. , Prelec K. , Raparia D. , Ritter J. , Zajic V.
Published: March 2008

In order to provide a variety of ion species to the BNL relativistic heavy ion collider (RHIC) and NASA Space Radiation Laboratory facilities on a pulse-to-pulse basis, the BNL RHIC electron beam ion source (EBIS) will use injection of primary “seed” ions from external low charged ion sources. As part of the prototype for the RHIC EBIS low energy beam transport line, a switchyard for seed ion injection and extracted EBIS ion beams has been constructed. The ion injection line includes a hollow cathode ion source (HCIS), four quadrupole lenses, a switchyard, gridded lenses, and other deflection optics. The HCIS is based on one obtained from CEA Saclay [B. Visentin et al., Phys. Scr., T 71, 204 (1997).] and has been used in bench studies in the production of low charged metal and gas ions, as well as in BNL test EBIS injection studies for the production of highly charged ions. The HCIS geometry and extraction optics have been modified to be able to reach the output currents necessary to seed the test EBIS. Ion currents greater than 60μA Cu+ and 130μA Ne+ have been extracted from the modified HCIS at 12–15kV and plasma aperture of 1–1.5mm. The HCIS discharge is initiated by a rf coil and can be operated stably at pulse rates from 1to100Hz. Measurement of the emittance of injector beam before and after the injection switchyard will be provided, as well as results from ion injection into the test EBIS using the new injector configuration.
Direct demonstration of the completeness of the eigenstates of the Schrödinger equation with local and nonlocal potentials bearing a Coulomb tail
Authors: Michel N.
Published: March 2008

Demonstrating the completeness of wave function solutions of the radial Schrödinger equation is a very difficult task. Existing proofs, relying on operator theory, are often very abstract and far from intuitive comprehension. However, it is possible to obtain rigorous proofs amenable to physical insight, if one restricts the considered class of Schrödinger potentials. One can mention, in particular, unbounded potentials yielding a purely discrete spectrum and short-range potentials. However, those possessing a Coulomb tail, very important for physical applications, have remained problematic due to their long-range character. The method proposed in this paper allows to treat them correctly, provided that the non-Coulomb part of potentials vanishes after a finite radius. Nonlocality of potentials can also be handled. The main idea in the proposed demonstration is that regular solutions behave like sine/cosine functions for large momenta, so that their expansions verify Fourier transform properties. The highly singular point at k=0 of long-range potentials is dealt with properly using analytical properties of Coulomb wave functions. Lebesgue measure theory is avoided, rendering the demonstration clear from a physical point of view.
Optical properties of InAs quantum dots grown on patterned Si with a thin GaAs buffer layer
Authors: Zhao Zuoming , Hao Zhibiao , Yadavalli Kameshwar , Wang Kang L. , Jacob Ajey P.
Published: March 2008

InAs quantum dots (QDs) were grown on patterned Si substrates with a thin GaAs buffer using SiO2 as a mask by molecular beam epitaxy. GaAs was firstly selectively grown on the exposed Si surface with feature size around 250nm. The InAs QDs were selectively grown on top of the GaAs. Low temperature photoluminescence (PL) measurements show strong optical activity in the wavelength range from 900to1050nm. The temperature dependent measurement of the PL response indicates that, for temperatures over 110K, the carrier escape from quantum dots leads to quenching of the signal. The PL results demonstrate that using nanostructures, it is possible to integrate high quality direct gap III-V materials on Si with high optical activity, leading to potentially new optoelectronic applications on Si and other convenient substrates which are lattice mismatched to InAs and other III-V materials.
Optimization of perpendicular recording on exchange coupled composite media
Authors: Tang Yuhui , Zhu Jian-Gang , Hong Sooyoul , Che Xiaodong
Published: March 2008

Using micromagnetic modeling, the recording performance of exchange coupled composite (ECC) media with perpendicular heads was systematically studied. The simulations indicated that the switching field angular dependency of ECC media is similar to the continuous media switching behavior. By tuning the magnetic properties of the soft∕hard layers, it was found that a soft layer with high saturation magnetization and low anisotropy energy caused large dc noise and unfavorable Adjacent Track Erasure (ATE) performance in recording, which is mainly due to the small nucleation field. A quantitative optimization of ECC media was given. Recording with different head designs on ECC media was also evaluated and this showed that large head field gradients at both the trailing edge and track edges are crucial to the implementation of ECC media at high recording areal density.
Current-induced magnetization dynamics in Co∕Cu∕Co nanopillars
Authors: Ma X. Q. , Xiao Z. H. , Wu P. P. , Zhang J. X. , Shi S. Q. , Chen L. Q.
Published: March 2008

We studied current-induced magnetization dynamics in Co∕Cu∕Co nanopillars using the Landau-Lifshitz-Gilbert equation incorporating the spin transfer torque effect. We show that the magnetization dynamics can be grouped into four types according to its characteristics and the current density value under zero external field. It is found that an external field can significantly affect the magnetization dynamics, either favoring or impeding the magnetization switching depending on its direction.
Numerical analysis of the magneto-Seebeck effect of bismuth with anisotropic band structure
Authors: Teramoto Takayuki , Komine Takashi , Kuraishi Masahiro , Sugita Ryuji , Hasegawa Yasuhiro , Nakamura Hiroaki
Published: March 2008

We studied the influence of band structure on the Seebeck coefficient of bismuth under a magnetic field. In this study, the magneto-Seebeck coefficient was calculated by solving the Boltzmann equation with an energy-dependent relaxation-time approximation and by assuming the Lax model of the bismuth band structure, which contains the anisotropy of bismuth. The influence of the scattering factor on the magneto-Seebeck effect was also investigated in the anisotropic band structure. The magneto-Seebeck coefficient varies with the magnetic field direction. Improvement of the Seebeck coefficient under a transverse magnetic field is higher than that under a longitudinal magnetic field. For the acoustic deformation potential scattering, the Seebeck coefficient is improved in a low magnetic field. For other types of scattering, the absolute values of the Seebeck coefficient are decreased in the low magnetic field. Moreover, for scattering factor r of 0, the magneto-Seebeck coefficient for a parabolic band does not vary, while the magneto-Seebeck coefficient for a nonparabolic band decreases. The sign of the Seebeck coefficient was changed under a high magnetic field because of the increase in magnetoresistivity due to high electron mobility. The effect of impurity addition was also investigated by changing the Fermi energy. With increasing Fermi energy, the Seebeck coefficient is more easily affected by an applied magnetic field, because the electron density is increased.
Influence of capping layer and atomic interdiffusion on the strain distribution in single and double self-assembled InAs∕GaAs quantum dots
Authors: Yang Mou , Xu S. J. , Wang Jian
Published: March 2008

The strain distribution in single and double self-assembled InAs∕GaAs quantum dots is theoretically investigated by using a valence-force-field model. The results show strong influence of the capping conditions on the strain distribution in individual and stacked dots with wetting layers. In particular, the intermixing of atoms is incorporated into the strain calculations, leading to a conclusion that the atomic intermixing can notably modify the strain profiles near the interfaces of the stacked dot system.
Filamentation instability in a quantum magnetized plasma
Authors: Bret A.
Published: March 2008

The filamentation instability occurring when a nonrelativistic electron beam passes through a quantum magnetized plasma is investigated by means of a cold quantum magnetohydrodynamic model. It is proved that the instability can be completely suppressed by quantum effects if and only if a finite magnetic field is present. A dimensionless parameter is identified that measures the strength of quantum effects. Strong quantum effects allow for a much smaller magnetic field to suppress the instability than in the classical regime.
The Hopf algebra structure of the Z3-graded quantum supergroup GLq,j(1∣1)
Authors: Celik Salih , Yasar Ergün
Published: March 2008

In this work, we give some features of the Z3-graded quantum supergroup.
Spreading fronts in sedimentation of dilute suspension of spheres
Authors: Gómez Daniel Chehata , Bergougnoux Laurence , Guazzelli Élisabeth , Hinch John
Published: March 2008

The thickness of the diffuse front between a sedimenting dilute suspension and the clear fluid above grows linearly in time due to polydispersity in the size of the particles and due to a hydrodynamic effect in which randomly heavy clusters fall out of the front leaving it depleted. Experiments and simplified point-particle numerical simulations agree that these two effects are not simply linearly additive.
Experimental characterization and cell interactions of a two-dimensional isotropic left-handed metamaterial
Authors: Zhang Jingjing , Chen Hongsheng , Ran Lixin , Luo Yu , Wu Bae-Ian , Kong Jin Au
Published: March 2008

We experimentally realized a two-dimensional (2D) isotropic left-handed material based on a cross-embedded S-ring resonator. Experimental results show that the 2D metamaterial with cross embedded arrangement exhibits much better performance than that with conventional arrangement. Theoretical interpretations are proposed, showing a reduced coupling between the rings that are located in the two orthogonal directions.
Alternatives to cosmological inflation
Authors: Brandenberger Robert
Published: March 2008

Inflationary cosmology is elegant and can claim significant predictive successes. But its attendant difficulties have motivated competing scenarios that also agree with observation.
Rolling Perception without Rolling Motion
Authors: Oh Songjoo , Shiffrar Maggie
Published: March 2008

The texture of a rolling circle depicts the translational and rotational components of its motion. In the case of a homogeneous circle, however, visual cues to the rotational component of motion are absent. To examine how the visual system resolves undetermined motion cues, optically neutral circles were displaced so that changes in their orientation were invisible. Contextual cues systematically triggered the perception of illusory rotation, suggesting that the visual system uses contextual cues along with intrinsic surface cues to compute percepts of rolling objects. This might also explain why people rarely experience the perception of ambiguous motion.
Effect of Intrapartum Antibiotic Prophylaxis Against Group B Streptococcal Infection on Comparisons of Rates of Endometritis and Urinary Tract Infection in Multicenter Surveillance
Authors: Dumas Anne-Marie , Girard Raphaëlle , Ayzac Louis , Beaumont Geneviève , Caillat-Vallet Emmanuelle , Depaix Florence , Gignoux Chantal , Haond Catherine , Pral Noelle , Robert Jacqueline , Tissot-Guerraz Françoise , Vincent-Bouletreau Agnès , Berland Michel , Fabry Jacques
Published: March 2008

Objective.

To establish whether antibiotic prophylaxis against group B streptococcal infection may be a confounding factor in comparisons of rates of endometritis and urinary tract infection after vaginal delivery.

Design.

Prospective study.

Setting.

Maternity units at 48 hospitals in a regional surveillance network in France during 2001-2004.

Methods.

The maternity units used a common protocol to establish whether antibiotic prophylaxis was indicated. Risk factors for endometritis and urinary tract infections were evaluated using multiple logistic regression.

Results.

We analyzed 49,786 vaginal deliveries. The percentage of women receiving antibiotic prophylaxis varied widely and significantly among the maternity units (range, 4.4%-26.0%; median, 15.8%; 25th percentile, 12.1%; 75th percentile, 19.0%) (P < .001, by Mantel-Haenszel χ2 test). The incidence rate of endometritis was significantly reduced from 0.25% to 0.11% by antibiotic prophylaxis (P = .001). There was a decrease in the incidence of urinary tract infection from 0.37% to 0.32%, but it was not statistically significant (P = .251).

Conclusions.

A reduction in the incidence of endometritis was observed when intrapartum antibiotic prophylaxis against group B streptococcal infection was used. However, the proportion of women considered to be at risk of infection varied widely among institutions. Comparisons of rates of endometritis among maternity units, but not urinary tract infection rates, should take into account antibiotic prophylaxis as a significant confounding factor.
Meiotic failure in male mice lacking an X-linked factor
Authors: Yang Fang , Gell Katarina , van der Heijden Godfried W. , Eckardt Sigrid , Leu N. Adrian , Page David C. , Benavente Ricardo , Her Chengtao , Höög Christer , McLaughlin K. John , Wang Peijing Jeremy
Published: March 2008

Meiotic silencing of sex chromosomes may cause their depletion of meiosis-specific genes during evolution. Here, we challenge this hypothesis by reporting the identification of TEX11 as the first X-encoded meiosis-specific factor in mice. TEX11 forms discrete foci on synapsed regions of meiotic chromosomes and appears to be a novel constituent of meiotic nodules involved in recombination. Loss of TEX11 function causes chromosomal asynapsis and reduced crossover formation, leading to elimination of spermatocytes, respectively, at the pachytene and anaphase I stages. Specifically, TEX11-deficient spermatocytes with asynapsed autosomes undergo apoptosis at the pachytene stage, while those with only asynapsed sex chromosomes progress. However, cells that survive the pachytene stage display chromosome nondisjunction at the first meiotic division, resulting in cell death and male infertility. TEX11 interacts with SYCP2, which is an integral component of the synaptonemal complex lateral elements. Thus, TEX11 promotes initiation and/or maintenance of synapsis and formation of crossovers, and may provide a physical link between these two meiotic processes.
The Ets transcription factor Elf5 specifies mammary alveolar cell fate
Authors: Oakes Samantha R. , Naylor Matthew J. , Asselin-Labat Marie-Liesse , Blazek Katrina D. , Gardiner-Garden Margaret , Hilton Heidi N. , Kazlauskas Michael , Pritchard Melanie A. , Chodosh Lewis A. , Pfeffer Peter L. , Lindeman Geoffrey J. , Visvader Jane E. , Ormandy Christopher J.
Published: March 2008

Hormonal cues regulate mammary development, but the consequent transcriptional changes and cell fate decisions are largely undefined. We show that knockout of the prolactin-regulated Ets transcription factor Elf5 prevented formation of the secretory epithelium during pregnancy. Conversely, overexpression of Elf5 in an inducible transgenic model caused alveolar differentiation and milk secretion in virgin mice, disrupting ductal morphogenesis. CD61+ luminal progenitor cells accumulated in Elf5-deficient mammary glands and were diminished in glands with Elf5 overexpression. Thus Elf5 specifies the differentiation of CD61+ progenitors to establish the secretory alveolar lineage during pregnancy, providing a link between prolactin, transcriptional events, and alveolar development.
Global histone acetylation induces functional genomic reorganization at mammalian nuclear pore complexes
Authors: Brown Christopher R. , Kennedy Caleb J. , Delmar Valerie A. , Forbes Douglass J. , Silver Pamela A.
Published: March 2008

The nuclear localization of genes is intimately tied to their transcriptional status in Saccharomyces cerevisiae, with populations of both active and silent genes interacting with components of the nuclear envelope. We investigated the relationship between the mammalian nuclear pore and the human genome by generating high-resolution, chromosome-wide binding maps of human nucleoporin 93 (Nup93) in the presence and absence of a potent histone deacetylase inhibitor (HDACI). Here, we report extensive genomic reorganization with respect to the nuclear pore following HDACI treatment, including the recruitment of promoter regions, euchromatin-rich domains, and differentially expressed genes. In addition to biochemical mapping, we visually demonstrate the physical relocalization of several genomic loci with respect to the nuclear periphery. Our studies show that inhibiting HDACs leads to significant changes in genomic organization, recruiting regions of transcriptional regulation to mammalian nuclear pore complexes.
Media for Mounting Fixed Cells on Microscope Slides
Authors: Fischer Andrew H. , Jacobson Kenneth A. , Rose Jack , Zeller Rolf
Published: March 2008

INTRODUCTION

After a specimen is labeled, coverslips containing cells or tissues are mounted onto microscope slides, or slides containing sections are overlaid with a coverslip. A number of recipes for commonly used mounting media are presented in this article, each with particular recommendations.
Labeling Lysosomes in Live Cells with Fluorescent Dyes for Imaging
Authors: Chazotte Brad
Published: March 2008

INTRODUCTION

The eukaryotic cell has evolved to compartmentalize its functions and transport various metabolites among cellular compartments. Therefore, in cell biology, the study of organization and structure/function relationships is of great importance. Lysosomes are membranous sacs--diverse in shape and size--containing more than 40 different acid hydrolases. The enzymes operate optimally at the acidic pH (~5) within the lysosome to break down various substances. It is thought that the highly glycosylated nature of the proteins of the Golgi membrane helps to protect them from degradation. A number of the fluorescent approaches to visualizing lysosomes make use of their acidic pH. Commonly used probes include neutral red, N-(3-[2,4-dinitrophenyl amino] propyl)-N-(3-aminopropyl)methylamine (DAMP), and acridine orange (a DNA stain). This protocol describes the labeling of lysosomes in live cells with neutral red.
Culture of HEK293-EBNA1 Cells for Production of Recombinant Proteins
Authors: Tom Roseanne , Bisson Louis , Durocher Yves
Published: March 2008

INTRODUCTION

Fast and efficient production of recombinant proteins (r-proteins) remains a major challenge for the academic and biopharmaceutical communities. Pure r-proteins are often required in large amounts (hundreds of milligrams to gram quantities) when being developed as biotherapeutics, or in smaller quantities (milligrams) for high-throughput screening campaigns and structural or functional studies. Mammalian cells are often preferred over prokaryotic systems when expressing cDNAs of mammalian origin due to their superior capability to conduct elaborate post-translational modifications. Large-scale transfection of mammalian cells is now establishing itself as a “must-have” technology in the scientific community, as it allows the production of milligram to gram quantities of r-proteins within a few days after cDNA cloning into the appropriate expression vector. The HEK293 cell line stably expressing the Epstein-Barr virus nuclear antigen-1 (HEK293-EBNA1, or 293E) is the most commonly used cell line for large-scale transfection. When using expression vectors bearing the Epstein-Barr virus origin of replication, oriP (such as the pTT vector), a threefold improvement in r-protein yield is generally obtained over a similar non-oriP vector. This protocol describes a method for culturing HEK293-EBNA1 cells which will then be used to produce recombinant proteins.
Transfection of HEK293-EBNA1 Cells in Suspension with Linear PEI for Production of Recombinant Proteins
Authors: Tom Roseanne , Bisson Louis , Durocher Yves
Published: March 2008

INTRODUCTION

Fast and efficient production of recombinant proteins (r-proteins) remains a major challenge for the academic and biopharmaceutical communities. Pure r-proteins are often required in large amounts (hundreds of milligrams to gram quantities) when being developed as biotherapeutics, or in smaller quantities (milligrams) for high-throughput screening campaigns and structural or functional studies. Mammalian cells are often preferred over prokaryotic systems when expressing cDNAs of mammalian origin due to their superior capability to conduct elaborate post-translational modifications. Large-scale transfection of mammalian cells is now establishing itself as a “must-have” technology in the scientific community, as it allows the production of milligram to gram quantities of r-proteins within a few days after cDNA cloning into the appropriate expression vector. Although calcium-mediated large-scale transfection is very effective, it is usually achieved in serum-containing medium under tightly controlled conditions that are difficult to achieve on a large scale. In contrast, polyethylenimine (PEI) is much easier to use: It binds to and precipitates DNA efficiently and the resulting DNA-PEI complexes are suitable for efficient transfection of mammalian cells. PEI has been used successfully on a large scale in serum-containing and serum-free cultures. In particular, the linear isoform of PEI is more effective for transfecting cells in suspension. This protocol describes the steps needed for successful transfection of HEK293 cells adapted to serum-supplemented or serum-free medium in suspension culture using linear PEI.
Transfection of Adherent HEK293-EBNA1 Cells in a Six-Well Plate with Branched PEI for Production of Recombinant Proteins
Authors: Tom Roseanne , Bisson Louis , Durocher Yves
Published: March 2008

INTRODUCTION

Fast and efficient production of recombinant proteins (r-proteins) remains a major challenge for the academic and biopharmaceutical communities. Pure r-proteins are often required in large amounts (hundreds of milligrams to gram quantities) when being developed as biotherapeutics, or in smaller quantities (milligrams) for high-throughput screening campaigns and structural or functional studies. Mammalian cells are often preferred over prokaryotic systems when expressing cDNAs of mammalian origin due to their superior capability to conduct elaborate post-translational modifications. Large-scale transfection of mammalian cells is now establishing itself as a “must-have” technology in the scientific community, as it allows the production of milligram to gram quantities of r-proteins within a few days after cDNA cloning into the appropriate expression vector. Although calcium-mediated large-scale transfection is very effective, polyethylenimine (PEI) is much easier to use: It binds to and precipitates DNA efficiently and the resulting DNA-PEI complexes are suitable for efficient transfection of mammalian cells. In particular, the branched isoform of PEI works well for adherent cells, as it promotes their attachment to the plastic surface. It is thus very useful in experiments requiring multiple medium exchanges or washing steps following transfection. Also, when used in conjunction with six-well CellBIND plates, branched PEI can be used to adhere transfected cells when establishing stable cell lines. This protocol describes the steps needed for successful transfection of HEK293 cells adapted to serum-supplemented or serum-free medium in adherent culture using branched PEI.
The impact of an exotic social wasp (Vespula germanica) on the native arthropod community of north‐west Patagonia, Argentina: an experimental study
Authors: SACKMANN PAULA , FARJI‐BRENER ALEJANDRO , CORLEY JUAN
Published: March 2008

Abstract 1. Biological invasions are usually thought to have a negative impact on native communities. However, data supporting this idea are often based on comparative studies between invaded and non‐invaded areas, and are spatially and temporally limited.

2. The present study experimentally assessed the impact of an exotic wasp, Vespula germanica, on the native arthropod community of north‐west Patagonia during 3 years in an area of 80 ha. Vespula germanica is an exotic social vespid that invaded north‐west Patagonia 20 years ago. It has been suggested that its populations affect native arthropods because of its broad diet and also because Patagonia lacks natural enemies and potential competitors for these wasps.

3. Using wasp‐specific toxic baits, V. germanica abundance was reduced in five sites of native woodlands during 3 consecutive years. The abundance, species richness, and composition of arthropods between non‐poisoned (control) and poisoned sites was then compared, both before and after the wasps were poisoned.

4. Wasp abundance represented 6% of the total arthropod catches in non‐poisoned sites and was reduced, on average, by 50% in the treated areas. The abundance, species richness, and composition of the arthropod community (305 species, 24 600 individuals) did not differ between control areas and areas where the abundance of V. germanica was reduced. Significant differences in response variables were found only before wasp poisoning had begun and were related to variations among sites.

5. These results suggest that V. germanica is not affecting the local arthropod assemblages, contradicting past work in other regions. The low relative abundance of wasps in Patagonia, when compared with other invaded regions, might explain the findings.

6. The present study provides further evidence for the importance of large‐scale experimental work with before/after comparisons to fully understand the impact of invaders on natural communities.
Estimating the population size of specialised solitary bees
Authors: LARSSON MAGNUS , FRANZÉN MARKUS
Published: March 2008

Abstract 1. Reliable methods for quantifying population size are crucial for strategies to conserve endangered wild‐bee species. Estimates of population size obtained through survey walks were compared with estimates obtained through mark–recapture studies in 10 populations of the red‐listed solitary bee Andrena hattorfiana in southern Sweden.

2. The mean number of bees observed during survey walks was strongly correlated with estimates of population size obtained with mark–recapture. It was found that 5.5–23.4% (mean 13.4%) of the total population was observed during an average survey walk.

3. One component in mark–recapture analysis is the measure of survival of individuals. In the largest bee population, females of A. hattorfiana that emerged in early season were found to forage for pollen on average 18.4 days.

4. The findings suggest that during large‐scale surveys, for example re‐inventories for red‐listed species, the population size of solitary bees can be quantified reliably and effectively by performing survey walks in a two‐step process. The first step consists of survey walks to establish the relationship between number of bee observations per survey walk and mark–recapture population size for a small set of populations. In the second, simple observation survey walks can be performed for a large set of populations. In each population of A. hattorfiana, it is recommended that at least six survey walks are performed.
C3 contributes to the cross‐protective immunity induced by Babesia gibsoni phosphoriboprotein P0 against a lethal B. rodhaini infection
Authors: TERKAWI M. A. , ZHANG G. , JIA H. , ABOGE G. , GOO Y. K. , NISHIKAWA Y. , YOKOYAMA N. , IGARASHI I. , KAWAZU S. I. , FUJISAKI K. , XUAN X.
Published: March 2008

We have studied the impact of complement component 3 (C3) deficiency on the progression of lethal Babesia rodhaini infection in immune mice. A B. gibsoni ribosomal phosphoprotein P0 (BgP0) previously reported to be a cross‐protective antigen against Babesia infection was used to immunize C57BL/6 wild‐type (WT) and C3‐deficient (C3–/–) mice. Test mice were immunized intraperitoneally (i.p.) with recombinant BgP0 (rBgP0), while controls either were immunized with PBS or did not receive any immunization. Following the immunization regime, test WT mice induced a specifically strong humoral response consisting of mixed immunoglobulins IgG1 and IgG2 associated with high production of IFN‐γ in the supernatant of splenocytes. While test C3–/– mice had significantly decreased total IgG, IgG1 and IgG2b responses, the secretions of IL‐12 and IFN‐γ tended to be lower than those in WT mice. Furthermore, partial protection was only observed in rBgP0‐immunized WT mice but not in C3–/– mice or controls. Indeed, rBgP0‐immunized WT mice showed significant reductions in the initiation of parasitaemia correlated with delayed mortalities and considerable survival rates. Taken together, our results indicate that cross‐protection was impaired in C3–/– mice in view of the decrease in the antibody responses and cytokine production and the high susceptibility to infection.
Intuition in emergency nursing: A phenomenological study
Authors: Lyneham Joy , Parkinson Camillus , Denholm Carey
Published: March 2008

The evidence of experience of intuitive knowing in the clinical setting has to this point only been informal and anecdotal. Reported experiences thus need to be either validated or refuted so that its place in emergency nursing can be determined. The history, nature and component themes captured within the intuitive practice of emergency nursing are described. This study was informed by the philosophy and method of phenomenology. Participants were 14 experienced emergency nurses. Through their narrative accounts and recall of events their experience of knowing was captured. Through a Van Manen process and a Gadamerian analysis, six themes associated with the ways in which the participants experienced intuition in clinical practice, were identified. This paper reveals the six emerging themes as knowledge, experience, connection, feeling, syncretism and trust.
Redescribing reflective practice and evidence‐based practice discourses
Authors: Mantzoukas Stefanos , Watkinson Sue
Published: March 2008

This paper provides an analysis on the discourses of reflective practice and evidence‐based practice. It commences by examining the role of discourse in describing and defining our beliefs and attitudes. Consequently, it argues that each discourse is based on a certain epistemology, which in effect are language constructs that create realities and like all language constructs, the epistemology of each discourse is open to the possibility of being restructured. Sequentially, any discourse can (re)describe a different type of reality by providing a set of different words, values and beliefs. Eventually, by exposing the language play and the engineered binary of the reflective practice and the evidence‐based practice discourses it is concluded that these discourses are not mutually exclusive as they have been portrayed by most of the literature, but complementary ones. Finally, reflective practice and evidence‐based practice are re‐described as supplementary discourses and practitioners can simultaneously utilize both through the process of critical reflexivity.