bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-Markovian stochastic Schrödinger equations in different temperature regimes: A study of the spin-boson model
Authors: de Vega Inés , Alonso Daniel , Gaspard Pierre , Strunz Walter T.
Published: March 2005

Stochastic Schrödinger equations are used to describe the dynamics of a quantum open system in contact with a large environment, as an alternative to the commonly used master equations. We present a study of the two main types of non-Markovian stochastic Schrödinger equations, linear and nonlinear ones. We compare them both analytically and numerically, the latter for the case of a spin-boson model. We show in this paper that two linear stochastic Schrödinger equations, derived from different perspectives by Diósi, Gisin, and Strunz [Phys. Rev. A 58, 1699 (1998)], and Gaspard and Nagaoka [J. Chem. Phys. 13, 5676 (1999)], respectively, are equivalent in the relevant order of perturbation theory. Nonlinear stochastic Schrödinger equations are in principle more efficient than linear ones, as they determine solutions with a higher weight in the ensemble average which recovers the reduced density matrix of the quantum open system. However, it will be shown in this paper that for the case of a spin-boson system and weak coupling, this improvement does only occur in the case of a bath at high temperature. For low temperatures, the sampling of realizations of the nonlinear equation is practically equivalent to the sampling of the linear ones. We study further this result by analyzing, for both temperature regimes, the driving noise of the linear equations in comparison to that of the nonlinear equations.
Hydrodynamics of oscillating atomic force microscopy cantilevers in viscous fluids
Authors: Maali Abdelhamid , Hurth Cedric , Boisgard Rodolphe , Jai Cédric , Cohen-Bouhacina Touria , Aimé Jean-Pierre
Published: March 2005

We present a study of thermal noise of commercially available atomic force microscopy (AFM) cantilevers in air and in water. The purpose of this work is to investigate the oscillation behavior of a clamped AFM microlever in liquids. Up to eight vibration modes are recorded. The experimental results are compared to theoretical predictions from the hydrodynamic functions corresponding to rigid transverse oscillations of an infinitely long rectangular beam. Except for the low-frequency modes, the known hydrodynamic functions cannot describe the amount of dissipated energy due to the liquid motion induced by the cantilever oscillation. The observed variation of the damping coefficient is smaller than the one predicted. The difference at higher modes between the mentioned theoretical description and experimental results is discussed with the help of numerical solutions of the three-dimensional Navier–Stokes equation.
A millimeter/submillimeter velocity modulation spectrometer for studies of molecular ions
Authors: Savage C. , Ziurys L. M.
Published: March 2005

A millimeter/submillimeter direct absorption spectrometer has been constructed that employs velocity modulation to selectively detect molecular ions. The instrument consists of a phase-locked Gunn oscillator/Schottky diode multiplier source, a gas absorption cell, and an InSb hot-electron bolometer detector. The gas cell is a single-pass system with two ring-type discharge electrodes at either end, which are connected to an rf power supply. Modulation of the ac discharge at a rate of 50kHz and phase-sensitive detection at 1f allows for selective observation of molecular ion signals and suppression of absorption from neutral species. The spectrometer can also be used in source-modulated mode, where the signal-to-noise ratio for signals generated in an ac plasma are significantly better than for dc discharges. Combining source modulation with the ac discharge for signal detection and velocity modulation for ion identification provides a powerful technique for molecular ion spectroscopy at millimeter/submillimeter wavelengths. This instrument has been used to measure the pure rotational spectra of CO+, HCO+, and SH+ with better precision than previous studies.
Physical mechanisms of negative-bias temperature instability
Authors: Tsetseris L. , Zhou X. J. , Fleetwood D. M. , Schrimpf R. D. , Pantelides S. T.
Published: March 2005

We report first-principles calculations that elucidate the mechanisms that underlie key features of negative-bias temperature instability (NBTI). We show that the depassivation of Si–H bonds by protons released in the Si substrate is consistent with the observed increase in interface-trap density. The calculated activation energy of 0.36eV is in excellent agreement with observations for long stress times. Adequate amounts of hydrogen, needed to initiate depassivation, are likely to exist in the substrate, trapped in complexes with dopants. The role of holes in the H release mechanism is identified. Finally, we explain how the above mechanisms can account for various experimental NBTI observations.
Radiative and nonradiative recombination processes in InN films grown by metal organic chemical vapor deposition
Authors: Intartaglia R. , Maleyre B. , Ruffenach S. , Briot O. , Taliercio T. , Gil B.
Published: March 2005

The 800meV photoluminescence band in indium nitride is excited under pulsed excitation conditions and is investigated as a function of temperature and time. Our results are consistent with a composite photoluminescence feature composed of two overlapping bands separated by an ∼10meV splitting, with populations described by a thermal equilibrium model. Efficient nonradiative recombination channels rule both the temperature dependence of the time-integrated photoluminescence spectra and the recombination dynamics. At 10K, the radiative recombination time is of the order of 300ns, while the nonradiative recombination time, which is ruled by activation energy of 8meV, is about 100ps.
Adult human hematopoietic stem cells produce neurons efficiently in the regenerating chicken embryo spinal cord
Authors: Sigurjonsson Olafur E. , Perreault Marie-Claude , Egeland Torstein , Glover Joel C.
Published: March 2005

Hematopoietic stem cells (HSCs) have been proposed as a potential source of neural cells for use in repairing brain lesions, but previous studies indicate a low rate of neuronal differentiation and have not provided definite evidence of neuronal phenotype. To test the neurogenic potential of human HSCs, we implanted CD34+ HSCs from adult human bone marrow into lesions of the developing spinal cord in the chicken embryo and followed their differentiation by using immunohistochemistry, retrograde labeling, and electrophysiology. We find that human cells derived from the implanted population express the neuronal markers NeuN and MAP2 at substantially higher rates than previously reported. We also find that these cells exhibit neuronal cytoarchitecture, extend axons into the ventral roots or several segments in length within the spinal white matter, are decorated with synaptotagmin+ and GABA+ synaptic terminals, and exhibit active membrane properties and spontaneous synaptic potentials characteristic of functionally integrated neurons. Neuronal differentiation is accompanied by loss of CD34 expression. Careful examination with confocal microscopy reveals no signs of heterokaryons, and human cells never express a chicken-specific antigen, suggesting that fusion with host chicken cells is unlikely. We conclude that the microenvironment in the regenerating spinal cord of the chicken embryo stimulates substantial proportions of adult human HSCs to differentiate into full-fledged neurons. This may open new possibilities for a high-yield production of neurons from a patient's own bone marrow.
LPS induces the interaction of a transcription factor, LPS-induced TNF-α factor, and STAT6(B) with effects on multiple cytokines
Authors: Tang Xiaoren , Marciano Deborah Levy , Leeman Susan E. , Amar Salomon
Published: March 2005

TNF-α is a pivotal cytokine whose overproduction can be lethal. Previously, we identified a transcription factor, LPS-induced TNF-α factor (LITAF), that regulates TNF-α transcription. We now report the discovery and characterization of a regulatory cofactor that we call signal transducer and activator of transcription (STAT) 6(B) because of its considerable homology to STAT6 [here referred to as STAT6(A)]. The STAT6(B) gene expression was found to be activated by LPS. Furthermore, we show that cotransfection of STAT6(B) and LITAF induces an interaction between the two proteins, consequently forming a complex that subsequently translocates into the nucleus and up-regulates the transcription of cytokines. The effect of the complex on a panel of cytokines was tested. In addition, the specific role of LITAF in this complex was established with experiments, including RNA interference technology. Overall, these findings describe roles for LITAF, STAT6(B), and the LITAF-STAT6(B) complex in the regulation of inflammatory cytokines in response to LPS stimulation in mammalian cells.
Floral asymmetry involves an interplay between TCP and MYB transcription factors in
Antirrhinum
Authors: Corley Susie B. , Carpenter Rosemary , Copsey Lucy , Coen Enrico
Published: March 2005

To understand how genes control floral asymmetry, we have isolated and analyzed the role of the
RADIALIS
(
RAD
) gene in
Antirrhinum
. We show that the
RAD
gene encodes a small MYB-like protein that is specifically expressed in the dorsal region of developing flowers. RAD has a single MYB-like domain that is closely related to one of the two MYB-like domains of DIV, a protein that has an antagonistic effect to RAD on floral development. Interactions between
RAD
and other genes indicate that floral asymmetry depends on the interplay between two pairs of transcription factors. First, a pair of TCP proteins is expressed in dorsal regions of the floral meristem, leading to the activation of
RAD
in the dorsal domain. The RAD MYB-like protein then antagonizes the related DIV MYB-like protein, preventing DIV activity in dorsal regions. In addition to its role in dorsal regions, RAD acts nonautonomously on lateral regions either directly, through RAD protein movement, or indirectly, through a signaling molecule.
Phosphatidylinositol phosphate kinase type Iγ regulates dynamics of large dense-core vesicle fusion
Authors: Gong Liang-Wei , Di Paolo Gilbert , Diaz Ester , Cestra Gianluca , Diaz Maria-Elena , Lindau Manfred , De Camilli Pietro , Toomre Derek
Published: March 2005

Phosphatidylinositol-4,5-bisphosphate was proposed to be an important regulator of large dense-core vesicle exocytosis from neuroendocrine tissues. Here, we have examined the kinetics of secretion in chromaffin cells from mice lacking phosphatidylinositol phosphate kinase type Iγ, the major neuronal phosphatidylinositol-4-phosphate 5-kinase. Absence of this enzyme caused a reduction of the readily releasable vesicle pool and its refilling rate, with a small increase in morphologically docked vesicles, indicating a defect in vesicle priming. Furthermore, amperometry revealed a delay in fusion pore expansion. These results provide direct genetic evidence for a key role of phosphatidylinositol-4,5-bisphosphate synthesis in the regulation of large dense-core vesicle fusion dynamics.
Varicelloviruses avoid T cell recognition by UL49.5-mediated inactivation of the transporter associated with antigen processing
Authors: Koppers-Lalic Danijela , Reits Eric A. J. , Ressing Maaike E. , Lipinska Andrea D. , Abele Rupert , Koch Joachim , Rezende Marisa Marcondes , Admiraal Pieter , van Leeuwen Daphne , Bienkowska-Szewczyk Krystyna , Mettenleiter Thomas C. , Rijsewijk Frans A. M. , Tampé Robert , Neefjes Jacques , Wiertz Emmanuel J. H. J.
Published: March 2005

Detection and elimination of virus-infected cells by cytotoxic T lymphocytes depends on recognition of virus-derived peptides presented by MHC class I molecules. A critical step in this process is the translocation of peptides from the cytoplasm into the endoplasmic reticulum by the transporter associated with antigen processing (TAP). Here, we identified the bovine herpesvirus 1-encoded UL49.5 protein as a potent inhibitor of TAP. The expression of UL49.5 results in down-regulation of MHC class I molecules at the cell surface and inhibits detection and lysis of the cells by cytotoxic T lymphocytes. UL49.5 homologs encoded by two other varicelloviruses, pseudorabies-virus and equine herpesvirus 1, also block TAP. Homologs of UL49.5 are widely present in herpesviruses, acting as interaction partners for glycoprotein M, but in several varicelloviruses UL49.5 has uniquely evolved additional functions that mediate its participation in TAP inhibition. Inactivation of TAP by UL49.5 involves two events: inhibition of peptide transport through a conformational arrest of the transporter and degradation of TAP by proteasomes. UL49.5 is degraded along with TAP via a reaction that requires the cytoplasmic tail of UL49.5. Thus, UL49.5 represents a unique immune evasion protein that inactivates TAP through a unique two-tiered process.
Foxp3 interacts with nuclear factor of activated T cells and NF-κB to repress cytokine gene expression and effector functions of T helper cells
Authors: Bettelli Estelle , Dastrange Maryam , Oukka Mohamed
Published: March 2005

Scurfy mice, which are deficient in a functional Foxp3, exhibit a severe lymphoproliferative disorder and display generalized over-production of cytokines. Here, we show that, among the Foxp transcriptional factor family, which includes Foxp1, Foxp2, and Foxp3, only Foxp3 has the ability to inhibit IL-2, IL-4, and IFN-γ production by primary T helper cells. We found that Foxp3 physically associates with the Rel family transcription factors, nuclear factor of activated T cells (NFAT) and NF-κB, and blocks their ability to induce the endogenous expression of their target genes, including key cytokine genes. More importantly, T cells derived from scurfy mice have a dramatic increase in nuclear factor of activated T cells (NFAT) and NF-κB transcriptional activity compared with the T cells derived from WT mice. Furthermore, complementation of Foxp3 in scurfy-derived T cells lowers the NFAT and NF-κB transcriptional activity to the physiological level. Finally, we show that myelin proteolipid protein-specific autoreactive T cells transduced with Foxp3 cannot mediate experimental autoimmune encephalomyelitis, providing further support that Foxp3 suppresses the effector function of autoreactive T cells. Foxp3 has already been associated with the generation of CD4+CD25+regulatory T cells; our data additionally demonstrate that Foxp3 suppresses the effector functions of T helper cells by directly inhibiting the activity of two key transcription factors, NFAT and NF-κB, which are essential for cytokine gene expression and T cell functions.
Characterization of the Lotus japonicus Symbiotic Mutant lot1 That Shows a Reduced Nodule Number and Distorted Trichomes
Authors: Ooki Yasuhiro , Banba Mari , Yano Koji , Maruya Jumpei , Sato Shusei , Tabata Satoshi , Saeki Kazuhiko , Hayashi Makoto , Kawaguchi Masayoshi , Izui Katsura , Hata Shingo
Published: March 2005

We isolated a recessive symbiotic mutant of Lotus japonicus that defines a genetic locus, LOT1 (for low nodulation and trichome distortion). The nodule number per plant of the mutant was about one-fifth of that of the wild type. The lot1 mutant showed a moderate dwarf phenotype and distorted trichomes, but its root hairs showed no apparent differences to those of the wild type. Infection thread formation after inoculation of Mesorhizobium loti was repressed in lot1 compared to that in the wild type. The nodule primordia of lot1 did not result in any aborted nodule-like structure, all nodules becoming mature and exhibiting high nitrogen fixation activity. The mutant was normally colonized by mycorrhizal fungi. lot1 also showed higher sensitivity to nitrate than the wild type. The grown-up seedlings of lot1 were insensitive to any ethylene treatments with regard to nodulation, although the mutant showed normal triple response on germination. It is conceivable that a nodulation-specific ethylene signaling pathway is constitutively activated in the mutant. Grafting experiments with lot1 and wild-type seedlings suggested that the root genotype mainly determines the low nodulation phenotype of the mutant, while the trichome distortion is regulated by the shoot genotype. Grafting of har1-4 shoots to lot1 roots resulted in an intermediate nodule number, i.e. more than that of lot1 and less than that of har1-4. Putative double mutants of lot1 and har1 also showed intermediate nodulation. Thus, it was indicated that LOT1 is involved in a distinct signal transduction pathway independent of HAR1.
Dynamics of Exogenous Nitrogen Partitioning and Nitrogen Remobilization from Vegetative Organs in Pea Revealed by 15N in Vivo Labeling throughout Seed Filling
Authors: Schiltz Séverine , Munier-Jolain Nathalie , Jeudy Christian , Burstin Judith , Salon Christophe
Published: March 2005

The fluxes of (1) exogenous nitrogen (N) assimilation and (2) remobilization of endogenous N from vegetative plant compartments were measured by 15N labeling during the seed-filling period in pea (Pisum sativum L. cv Caméor), to better understand the mechanism of N remobilization. While the majority (86%) of exogenous N was allocated to the vegetative organs before the beginning of seed filling, this fraction decreased to 45% at the onset of seed filling, the remainder being directed to seeds. Nitrogen remobilization from vegetative parts contributed to 71% of the total N in mature seeds borne on the first two nodes (first stratum). The contribution of remobilized N to total seed N varied, with the highest proportion at the beginning of filling; it was independent of the developmental stage of each stratum of seeds, suggesting that remobilized N forms a unique pool, managed at the whole-plant level and supplied to all filling seeds whatever their position on the plant. Once seed filling starts, N is remobilized from all vegetative organs: 30% of the total N accumulated in seeds was remobilized from leaves, 20% from pod walls, 11% from roots, and 10% from stems. The rate of N remobilization was maximal when seeds of all the different strata were filling, consistent with regulation according to the N demand of seeds. At later stages of seed filling, the rate of remobilization decreases and may become controlled by the amount of residual N in vegetative tissues.
The sectional anatomy of the carpal tunnel and its related neurovascular structures studied by using plastination
Authors: Sora M.‐C. , Genser‐Strobl B.
Published: March 2005

The aim of this study was to evaluate the morphology of the carpal tunnel and its related neurovascular structures. A slice anatomy study was performed on 12 right wrists of unfixed human cadavers by using the plastination technique. The measurements were performed at the level of the pisiform, hook of the hamate and in the middle between these structures. The diameters of the carpal tunnel and the median nerve were measured at the level of the hook of the hamate. The median nerve can be predicted to be 18 ± 1.6 mm radial to the pisiform and the ulnar neurovascular bundle 6.8 ± 1.4 mm radial to the pisiform. Between those structures there will be at least a 9‐mm area, localized 8 mm radial to the pisiform, where the incision of the transverse carpal ligament could be performed risk‐free. At the hamate hook the median nerve can be predicted at 9.24 ± 1.18 mm and the ulnar artery lies usually 1.26 ± 2.5 mm radial to the hook. An understanding of the contents and their positions, and relationships to each other allows an accurate identification of neurovascular structures in the carpal tunnel. Our findings can be used as anatomic landmarks of the carpal tunnel and could be helpful to physicians performing carpal tunnel investigations.
Viral encephalitis: a review of diagnostic methods and guidelines for management
Authors: Steiner I. , Budka H. , Chaudhuri A. , Koskiniemi M. , Sainio K. , Salonen O. , Kennedy P. G. E.
Published: March 2005

Viral encephalitis is a medical emergency. The spectrum of brain involvement and the prognosis are dependent mainly on the specific pathogen and the immunological state of the host. Although specific therapy is limited to only several viral agents, correct immediate diagnosis and introduction of symptomatic and specific therapy has a dramatic influence upon survival and reduces the extent of permanent brain injury in survivors. We searched MEDLINE (National Library of Medicine) for relevant literature from 1966 to May 2004. Review articles and book chapters were also included. Recommendations are based on this literature based on our judgment of the relevance of the references to the subject. Recommendations were reached by consensus. Where there was lack of evidence but consensus was clear we have stated our opinion as good practice points. Diagnosis should be based on medical history, examination followed by analysis of cerebrospinal fluid for protein and glucose contents, cellular analysis and identification of the pathogen by polymerase chain reaction (PCR) amplification (recommendation level A) and serology (recommendation level B). Neuroimaging, preferably by magnetic resonance imaging, is an essential aspect of evaluation (recommendation level B). Lumbar puncture can follow neuroimaging when immediately available, but if this cannot be obtained at the shortest span of time it should be delayed only in the presence of strict contraindications. Brain biopsy should be reserved only for unusual and diagnostically difficult cases. All encephalitis cases must be hospitalized with an access to intensive care units. Supportive therapy is an important basis of management. Specific, evidence‐based, anti‐viral therapy, acyclovir, is available for herpes encephalitis (recommendation level A). Acyclovir might also be effective for varicella‐zoster virus encephalitis, gancyclovir and foscarnet for cytomegalovirus encephalitis and pleconaril for enterovirus encephalitis (IV class of evidence). Corticosteroids as an adjunct treatment for acute viral encephalitis are not generally considered to be effective and their use is controversial. Surgical decompression is indicated for impending uncal herniation or increased intracranial pressure refractory to medical management.
Development of cardiovascular function in the horse fetus
Authors: Giussani Dino A. , Forhead Alison J. , Fowden Abigail L.
Published: March 2005

In mammals, the mechanisms regulating an increase in fetal arterial blood pressure with advancing gestational age remain unidentified. In all species studied to date, the prepartum increase in fetal plasma cortisol has an important role in the maturation of physiological systems essential for neonatal survival. In the horse, the prepartum elevation in fetal cortisol and arterial blood pressure are delayed relative to other species. Hence, the mechanisms governing the ontogenic increase in arterial blood pressure in the horse fetus may mature much closer to term than in other fetal animals. In the chronically instrumented pony mare and fetus, this study investigated how changes in fetal peripheral vascular resistance, in plasma concentrations of noradrenaline, adrenaline and vasopressin, and in the maternal‐to‐fetal plasma concentration gradient of oxygen and glucose relate to the ontogenic changes in fetal arterial blood pressure and fetal plasma cortisol concentration as term approaches. The data show that, towards term in the horse fetus, the increase in arterial blood pressure occurs together with reductions in metatarsal vascular resistance, elevations in plasma concentrations of cortisol, vasopressin, adrenaline and noradrenaline, and falls in the fetal : maternal ratio of blood P and glucose concentration. Correlation analysis revealed that arterial blood pressure was positively related with plasma concentrations of vasopressin and noradrenaline, but not adrenaline in the fetus, and inversely related to the fetal : maternal ratio of blood P, but not glucose, concentration. This suggests that increasing vasopressinergic and noradrenergic influences as well as changes in oxygen availability to the fetus and uteroplacental tissues may contribute to the ontogenic increase in fetal arterial blood pressure towards term in the horse.
Launching Performance Analysis of a Continuously Variable Transmission Vehicle With Different Torsional Couplings
Authors: Kim Jungyun
Published: March 2005

This article describes the launching behaviors of passenger cars equipped with continuously variable transmission (CVT), which have different torsional couplings: a torsion damper and a dual mass flywheel. To reduce the driveline vibration and noise, a torsional coupling is installed in the CVT vehicle, in which the wet type multiplate clutch is used as a start device. In addition, a torsional coupling makes considerable effects on the launching performance of a vehicle. The launching performances, considered here, are the acceleration performance with various throttle positions and the transient characteristics of vehicle creep and throttle tip-in. By using the mathematical models of each driveline component, we developed a simulation program to investigate the launching performance in various launching conditions. In order to verify our simulation program, we performed the road test of a prototype vehicle that has torsion damper as a torsional coupling. Finally, we analyzed and compared the launching performances in two cases of a torsion damper and a dual mass flywheel using the developed simulation program.
Experimental Determination of the Effect of Disjoining Pressure on Shear in the Contact Line Region of a Moving Evaporating Thin Film
Authors: Panchamgam Sashidhar S. , Gokhale Shripad J. , Plawsky Joel L. , DasGupta Sunando , Wayner, Peter C.
Published: March 2005

The thickness and curvature profiles in the contact line region of a moving evaporating thin liquid film of pentane on a quartz substrate were measured for the thickness region, δ<2.5 μm. The critical region, δ<0.1 μm, was emphasized. The profiles were obtained using image-analyzing interferometry and an improved data analysis procedure. The precursor adsorbed film, the thickness, the curvature, and interfacial slope (variation of the local “apparent contact angle”) profiles were consistent with previous models based on interfacial concepts. Isothermal equilibrium conditions were used to verify the accuracy of the procedures and to evaluate the retarded dispersion constant in situ. The profiles give fundamental insight into the phenomena of phase change, pressure gradient, fluid flow, spreading, shear stress, and the physics of interfacial phenomena in the contact line region. The experimental results demonstrate explicitly, for the first time with microscopic detail, that the disjoining pressure controls fluid flow within an evaporating completely wetting thin curved film.
Modulated Air Layer Heat and Moisture Transport by Ventilation and Diffusion From Clothing With Open Aperture
Authors: Ghaddar Nesreen , Ghali Kamel , Harathani Jihad
Published: March 2005

A two-dimensional model is developed for the modulated internal airflow, due to walking, in the gap between clothing and skin surface in the presence of clothing apertures. The normal airflow renewing the air layer through the fabric is modeled using the Ghali et al. three-node fabric ventilation model with corrected heat and moisture transport coefficients within the fabric voids to include the diffusion-dominated transport processes in the fabric at low normal flow rates that occur near the open aperture. The parallel flow is induced by a periodic pressure difference between environmental pressure at the aperture of the clothing system and trapped air layer pressure. The parallel flow in the trapped air layer is assumed to be locally governed by the Womersley solution of time-periodic laminar flow in a plane channel. The two-dimensional (2D) model that uses, in the parallel direction, the Womersley flow of the trapped air layer has predicted significantly lower flow rates than a model based on an inertia-free quasi-steady Poisueille flow model (valid only at low ventilation frequencies). In addition, the model predicted lower sensible and latent heat losses from the sweating skin in the presence of open apertures in the clothing system. The percentage drop in total heat loss due to open aperture is 7.52%, and 2.63%, at ventilation frequencies of 25, and 35 revolution per minute, respectively. The reported results showed that under walking conditions, a permeable clothing system with an open aperture reduced heat loss from the skin when compared to a normal ventilation model (closed aperture). These results were consistent with previously published empirical data of Lotens and Danielsson on air layer resistance for open and closed apertures in high air permeable fabrics.
bla
CTX-M
Genes in Clinical
Salmonella
Isolates Recovered from Humans in England and Wales from 1992 to 2003
Authors: Batchelor M. , Hopkins K. , Threlfall E. J. , Clifton-Hadley F. A. , Stallwood A. D. , Davies R. H. , Liebana E.
Published: March 2005

Cefotaximases (CTX-M) are a rapidly growing class A β-lactamase family that has been found among a wide range of clinical bacteria. One hundred and six isolates were selected from 278,308
Salmonella
isolates based on resistance to ampicillin and cephalosporins and subjected to further characterization. Fourteen isolates were
bla
CTX-M
PCR positive, and cefotaxime MICs for these isolates were ≥16 mg/liter. Furthermore, sequence analysis revealed the presence of type CTX-M9, -15, or -17 to -18. All 14 isolates presented different PFGE restriction profiles, although six
Salmonella enterica
serotype Virchow isolates formed a tight cluster. The
bla
CTX-M
genetic determinants were present in transferable plasmids of ∼63, 105, and >148 kb. Plasmid restriction analysis showed that both horizontal transfer of similar plasmids among different clones and transfer of genes between different plasmids were likely mechanisms involved in the spread of
bla
CTX-M
genes. We have found that CTX-M enzymes have emerged in community-acquired infections both linked to foreign travel and domestically acquired. This is the first report of a CTX-M enzyme in
Salmonella
in the United Kingdom. Also, it represents the first report of a
bla
CTX-M
gene in
Salmonella enterica
serotype Stanley and a
bla
CT
X
-M-15
gene in
Salmonella enterica
serotypes Anatum, Enteritidis, and Typhimurium.
Topical Caspofungin for Treatment of Keratitis Caused by
Candida albicans
in a Rabbit Model
Authors: Goldblum David , Frueh Beatrice E. , Sarra Gian-Marco , Katsoulis Konstantinos , Zimmerli Stefan
Published: March 2005

Candida albicans
is the most frequent cause of fungal keratitis in temperate regions. Caspofungin has potent activity against
Candida
spp. in a variety of clinical settings. Little is known, however, about its activity against fungal keratitis. We compared the efficacy of topical caspofungin with that of topical amphotericin B (AMB) in a rabbit model of experimental keratomycosis. Keratitis was induced with a standardized inoculum of
Candida albicans
(SC 5314) placed on the debrided cornea. Twenty-four hours after infection, animals were randomly assigned to treatment with 0.15% caspofungin, 0.5% caspofungin, 0.15% AMB, and a saline control (
n
= 12 rabbits in each group). For the first 12 h, treatment was repeated every 30 min and, after a 12-h pause, was resumed at hourly intervals for another 12 h. The animals were examined and killed 12 h after administration of the last dose. Treatment effects were evaluated by clinical assessment, fungal culture, and histopathology. Drug treatment significantly reduced corneal fungal recovery from 3.78 log
10
CFU in saline-treated animals to 2.97, 1.76, and 1.18 log
10
CFU in animals treated with 0.15% caspofungin, 0.5% caspofungin, and 0.15% AMB, respectively. By histopathology, the mean hyphal density was significantly lower in the corneas of treated animals than in those of the controls; there was no difference in hyphal densities between the different treatment groups. The depth of corneal invasion was not significantly reduced by the antifungal treatments. By clinical assessment, keratitis progressed in animals treated with saline, whereas disease progression was inhibited by all drug treatment regimens. In our rabbit model, 0.5% caspofungin was as effective as 0.15% AMB for the topical treatment of
Candida
keratitis. The potential clinical efficacy of caspofungin awaits further investigation.
Cloning, Sequencing, and Characterization of the SdeAB Multidrug Efflux Pump of
Serratia marcescens
Authors: Kumar Ayush , Worobec Elizabeth A.
Published: March 2005

Serratia marcescens
is an important nosocomial agent known for causing various infections in immunocompromised individuals. Resistance of this organism to a broad spectrum of antibiotics makes the treatment of infections very difficult. This study was undertaken to identify multidrug resistance efflux pumps in
S. marcescens
. Three mutant strains of
S. marcescens
were isolated in vitro by the serial passaging of a wild-type strain in culture medium supplemented with ciprofloxacin, norfloxacin, or ofloxacin. Fluoroquinolone accumulation assays were performed to detect the presence of a proton gradient-dependent efflux mechanism. Two of the mutant strains were found to be effluxing norfloxacin, ciprofloxacin, and ofloxacin, while the third was found to efflux only ofloxacin. A genomic library of
S. marcescens
wild-type strain UOC-67 was constructed and screened for RND pump-encoding genes by using DNA probes for two putative RND pump-encoding genes. Two different loci were identified:
sdeAB
, encoding an MFP and an RND pump, and
sdeCDE
, encoding an MFP and two different RND pumps. Northern blot analysis revealed overexpression of
sdeB
in two mutant strains effluxing fluoroquinolones. Analysis of the
sdeAB
and
sdeCDE
loci in
Escherichia coli
strain AG102MB, deficient in the RND pump (AcrB), revealed that gene products of
sdeAB
are responsible for the efflux of a diverse range of substrates that includes ciprofloxacin, norfloxacin, ofloxacin, chloramphenicol, sodium dodecyl sulfate, ethidium bromide, and
n
-hexane, while those of
sdeCDE
did not result in any change in susceptibilities to any of these agents.
Comparative Efficacies of TAK-187, a Long-Lasting Ergosterol Biosynthesis Inhibitor, and Benznidazole in Preventing Cardiac Damage in a Murine Model of Chagas' Disease
Authors: Corrales Milagros , Cardozo Rubén , Segura María Asunción , Urbina Julio A. , Basombrío Miguel Angel
Published: March 2005

We carried out a comparative study of benznidazole and TAK-187, a long-lasting ergosterol biosynthesis inhibitor, with a murine model of Chagas' disease. The results indicated that TAK-187 was more effective than benznidazole in preventing
Trypanosoma cruzi
-induced cardiac damage in experimental animals.
Functional Characterization of OXA-57, a Class D β-Lactamase from
Burkholderia pseudomallei
Authors: Keith Karen E. , Oyston Petra C. , Crossett Ben , Fairweather Neil F. , Titball Richard W. , Walsh Timothy R. , Brown Katherine A.
Published: March 2005

Class D β-lactamase OXA-57 was identified in a range of isolates of
Burkholderia pseudomallei
and
Burkholderia thailandensis
. Comparative kinetic analyses of wild-type and mutant forms of
B. pseudomallei
OXA-57 are reported. Implications of these data for β-lactam resistance and the proposed role of Ser-104 in β-lactam hydrolysis are discussed.
Effects of montelukast on airway narrowing from eucapnic voluntary hyperventilation and cold air exercise
Authors: Rundell K W , Spiering B A , Baumann J M , Evans T M
Published: March 2005

Background:Exercise induced bronchoconstriction (EIB) is common in elite athletes. Eucapnic voluntary hyperventilation (EVH) is a laboratory test recommended for the identification of EIB in athletes, secondary to a field exercise challenge. Montelukast attenuates EIB, but its protective effect against airway narrowing from EVH has not been investigated.

Objective:To examine the effectiveness of montelukast after exercise and after EVH.

Methods:A randomised, placebo controlled, double blind, crossover study was performed with 11 physically active EIB positive subjects (eight men, three women; mean (SD) age 22.8 (6.8) years). Six hours before each of the following challenges 10 mg montelukast or placebo was ingested: (a) a six minute, cold air (−3°C) maximal effort work accumulation cycle ergometer exercise; (b) EVH, breathing 5% CO2compressed air at 85% maximal voluntary ventilation for six minutes. Spirometry was performed before and 5, 10, and 15 minutes after the challenge. At least 48 hours was observed between challenges.

Results:No differences in forced expiratory volume in one second (FEV1) were found after the two challenges. Exercise and EVH resulted in falls in FEV1of 22.4 (18.0) and 25.6 (16.8) respectively. Falls in FEV1after montelukast were less than after placebo (10.6 (10.6) and 14.3 (11.3) after exercise and EVH respectively; p<0.05). Montelukast provided protection against bronchoconstriction (59% and 53%; p<0.05) for eight exercising subjects and 10 EVH subjects; no protection was afforded for three exercising and one EVH challenged subject.

Conclusions:Both exercise and EVH were potent stimuli of airway narrowing. A single dose of montelukast provided reasonable protection in attenuating bronchoconstriction from either exercise or EVH. The similar protection by montelukast suggests that EVH is a suitable laboratory surrogate for EIB evaluation.
How do minimum cigarette price laws affect cigarette prices at the retail level?
Authors: Feighery E C , Ribisl K M , Schleicher N C , Zellers L , Wellington N
Published: March 2005

Objectives:Half of US states have minimum cigarette price laws that were originally passed to protect small independent retailers from unfair price competition with larger retailers. These laws prohibit cigarettes from being sold below a minimum price that is set by a formula. Many of these laws allow cigarette company promotional incentives offered to retailers, such as buydowns and master-type programmes, to be calculated into the formula. Allowing this provision has the potential to lower the allowable minimum price. This study assesses whether stores in states with minimum price laws have higher cigarette prices and lower rates of retailer participation in cigarette company promotional incentive programmes.

Design:Retail cigarette prices and retailer participation in cigarette company incentive programmes in 2001 were compared in eight states with minimum price laws and seven states without them. New York State had the most stringent minimum price law at the time of the study because it excluded promotional incentive programmes in its price setting formula; cigarette prices in New York were compared to all other states included in the study.

Results:Cigarette prices were not significantly different in our sample of US states with and without cigarette minimum price laws. Cigarette prices were significantly higher in New York stores than in the 14 other states combined.

Conclusions:Most existing minimum cigarette price laws appear to have little impact on the retail price of cigarettes. This may be because they allow the use of promotional programmes, which are used by manufacturers to reduce cigarette prices. New York’s strategy to disallow these types of incentive programmes may result in higher minimum cigarette prices, and should also be explored as a potential policy strategy to control cigarette company marketing practices in stores. Strict cigarette minimum price laws may have the potential to reduce cigarette consumption by decreasing demand through increased cigarette prices and reduced promotional activities at retail outlets.
Validity of self reports in a cohort of Swedish adolescent smokers and smokeless tobacco (snus) users
Authors: Post A , Gilljam H , Rosendahl I , Meurling L , Bremberg S , Galanti M R
Published: March 2005

Objective:To validate self reports of cigarette and smokeless tobacco (snus) use in a prospective cohort of adolescents.

Design:A cross sectional analysis of a cohort sub-sample.

Setting:County of Stockholm, Sweden.

Subjects:520 adolescents in the final grade of junior high school (mean age 15.0 years).

Main outcome measure:Concordance between self reported tobacco use and saliva cotinine concentration.

Results:Using a cut point of 5 ng/ml saliva cotinine to discriminate active tobacco use, there was a 98% concordance between self reported non-use in the past month and cotinine concentration. The sensitivity of the questionnaire compared to the saliva cotinine test, used as the gold standard, was 90% and the specificity 93%. One hundred and fifteen out of 520 subjects (22%) reported monthly tobacco use. Among these, 67% (46/69) of the exclusive cigarette smokers, 82% (23/28) of exclusive snus users, and 94% (15/16) of mixed users (cigarettes + snus) had cotinine concentrations above 5 ng/ml. Among subjects reporting daily use 96% (64/67) had saliva cotinine concentrations above the cut point. Exclusive current cigarette users were more likely to be classified discordantly by questionnaire and cotinine test compared to snus users (odds ratio 3.2, 95% confidence interval 1.2 to 8.6).

Conclusion:This study confirms the reliability of adolescents’ self reported tobacco use. In a context of low exposure to environmental tobacco smoke a cut off for saliva cotinine of 5 ng/ml reliably discriminated tobacco users from non-users. Irregular use of tobacco in this age group probably explains the discrepancy between self reported use and cotinine concentrations.
Reduced molecular expression of K+channel proteins in vascular smooth muscle from rats made hypertensive withNω-nitro-l-arginine
Authors: Bratz Ian N. , Dick Gregory M. , Partridge L. Donald , Kanagy Nancy L.
Published: March 2005

Smooth muscle membrane potential ( Em) depends on K+channels, and arteries from rats made hypertensive with Nω-nitro-l-arginine (LHR) are depolarized compared with control. We hypothesized that decreased K+channel function, due to decreased K+channel protein expression, underlies Emdepolarization. Furthermore, K+channel blockers should move control Em(−46 ± 1 mV) toward that in LHR (−37 ± 2 mV) and normalize contraction. The Emvs. K+relationship was less steep in LHR (23 ± 2 vs. 28 ± 1 mV/log K+concentration), and contractile sensitivity to K+was increased (EC50= 37 ± 1 vs. 23 ± 1 mM). Iberiotoxin (10 nM), an inhibitor of large-conductance Ca2+-activated K+(BKCa) channels, depolarized control and LHR Emto −35 ± 1 and −30 ± 2 mV, respectively; however, effects on K+sensitivity were more profound in LHR (EC50= 25 ± 2 vs. 15 ± 3 mM). The voltage-dependent K+(KV) channel blocker 4-aminopyridine (3 mM) depolarized control Emto the level of LHR (−28 ± 1 vs. −28 ± 1 mV); however, effects on K+sensitivity were greater in LHR (EC50= 17 ± 4 vs. 4 ± 4 mM). Western blots revealed reduced BKCaand KV1.5 channel expression in LHR arteries. The findings suggest that diminished expression of K+channels contributes to depolarization and enhanced contractile sensitivity. These conclusions are supported by direct electrophysiological assessment of BKCaand KVchannel function in control and LHR smooth muscle cells [see companion paper (Bratz IN, Swafford AN Jr, Kanagy NL, and Dick GM. Am J Physiol Heart Circ Physiol 289: H1284–H1290, 2005)].
Moderate endurance training prevents doxorubicin-induced in vivo mitochondriopathy and reduces the development of cardiac apoptosis
Authors: Ascensão António , Magalhães José , Soares José M. C. , Ferreira Rita , Neuparth Maria J. , Marques Franklim , Oliveira Paulo J. , Duarte José A.
Published: March 2005

The objective of this work was to test the hypothesis that endurance training may be protective against in vivo doxorubicin (DOX)-induced cardiomyopathy through mitochondria-mediated mechanisms. Forty adult (6–8 wk old) male Wistar rats were randomly divided into four groups ( n = 10/group): nontrained, nontrained + DOX treatment (20 mg/kg), trained (14 wk of endurance treadmill running, 60–90 min/day), and trained + DOX treatment. Mitochondrial respiration, calcium tolerance, oxidative damage, heat shock proteins (HSPs), antioxidant enzyme activity, and apoptosis markers were evaluated. DOX induces mitochondrial respiratory dysfunction, oxidative damage, and histopathological lesions and triggers apoptosis ( P < 0.05, n = 10). However, training limited the decrease in state 3 respiration, respiratory control ratio (RCR), uncoupled respiration, aconitase activity, and protein sulfhydryl content caused by DOX treatment and prevented the increased sensitivity to calcium in nontrained + DOX-treated rats ( P < 0.05, n = 10). Moreover, training inhibited the DOX-induced increase in mitochondrial protein carbonyl groups, malondialdehyde, Bax, Bax-to-Bcl-2 ratio, and tissue caspase-3 activity ( P < 0.05, n = 10). Training also increased by ∼2-fold the expression of mitochondrial HSP-60 and tissue HSP-70 ( P < 0.05, n = 10) and by ∼1.5-fold the activity of mitochondrial and cytosolic forms of SOD ( P < 0.05, n = 10). We conclude that endurance training protects heart mitochondrial respiratory function from the toxic effects of DOX, probably by improving mitochondrial and cell defense systems and reducing cell oxidative stress. In addition, endurance training limited the DOX-triggered apoptosis.
Dopamine type 2 receptor expression and function in rodent sensory neurons projecting to the airways
Authors: Peiser Christian , Trevisani Marcello , Groneberg David A. , Dinh Q. Thai , Lencer Doerthe , Amadesi Silvia , Maggiore Barbara , Harrison Selena , Geppetti Pierangelo , Fischer Axel
Published: March 2005

Agonists of the dopamine receptors have been demonstrated to have bronchodilatory properties in pathologically constricted airways. The mechanism by which these agonists induce bronchodilatation is thought to involve airway sensory nerves. In this study, the expression and function of dopamine D2receptor were examined in sensory ganglia supplying the airways. Neuronal dopamine D2receptor mRNA expression was demonstrated by single-cell RT-PCR following laser-assisted microdissection. The projection of the neurons to the airways was confirmed by retrograde neuronal labeling. In functional studies, dopamine D2receptor agonists (AR-C65116AB and ropinirole) inhibited intraneuronal calcium mobilization in rat capsaicin-sensitive primary sensory neurons and capsaicin-induced plasma extravasation in the rat trachea. Our results provide support to the hypothesis that dopamine D2receptor activation inhibits neurogenic inflammation and proinflammatory reflex responses.
Problems, possibilities, and pitfalls in studying the arterial baroreflexes’ influence over long-term control of blood pressure
Authors: Barrett Carolyn J. , Malpas Simon C.
Published: March 2005

While there is no disputing the critical role of baroreflexes in buffering rapid changes in arterial pressure, their role in long-term pressure control has become an area of controversy. Recent experiments using novel techniques have challenged the traditional view that arterial baroreflexes are not involved in setting chronic arterial pressure levels. Resetting of the arterial baroreflex, often used as an argument against the arterial baroreflex playing a role in long-term pressure control is rarely complete. The arterial baroreflex is just one of the many neural, hormonal, and intrinsic mechanisms involved in arterial pressure control and while the removal of the arterial baroreflex alone has little effect on mean arterial pressure it is too simplistic to suggest that the baroreflex has no role in long-term pressure control. Renal sympathetic nerve activity appears to be particularly resistant to resetting in response to ANG II-induced hypertension. Given the important role of the kidneys in long-term pressure control, we suggest there is a clear need to develop experimental techniques whereby sympathetic nerve activity to the kidneys and other organs can be monitored over periods of weeks to months.