bluuebunny/crossref_metadata_2025 huggingface dataset:
Short-term lifestyle modification alters circulating biomarkers of endothelial health in sedentary, overweight adults
Authors: Rector R. Scott , Turk James R. , Sun Grace Y. , Guilford Brianne L. , Toedebusch Brian W. , McClanahan Matt W. , Thomas Tom R.
Published: November 2006

Obesity and inactivity are associated with endothelial dysfunction that may contribute to the development of atherosclerosis. We examined the effects of a short-term lifestyle intervention on circulating biomarkers of endothelial health. Nineteen overweight or obese (mean body mass index (BMI): 28.9 ± 0.7 kg/m2) men and women underwent 6 weeks of body mass reduction induced by moderate energy restriction (~750 kcal/d; 1 kcal = 4.184 kJ) and aerobic training (~400 kcal/d). Fasting serum samples were collected at baseline and after reduction in body mass (week 6) to assess concentrations of nitrotyrosine (NT), secretory phospholipase A2 (sPLA2), and soluble intracellular adhesion molecule-1 (sICAM-1). Body mass was significantly reduced from 81.3 ± 2.8 to 77.3 ± 2.6 kg (p < 0.05). Circulating concentrations of NT and sICAM-1 were significantly reduced with treatment (~25% and ~10%, respectively), whereas sPLA2 levels were significantly elevated (~45%). Elevations in sPLA2 were negatively correlated with changes in NT (r = –0.58, p = 0.047); reductions in NT did not correlate significantly with reductions in sICAM-1. It appears that circulating markers of endothelial health are susceptible to short-term exercise interventions with modest reduction in body mass, and such a lifestyle modification may improve endothelial health by reducing protein nitration products and cellular adhesion.
A semiclassical, microscopic model for nuclear collective rotation
Authors: Gulshani P
Published: November 2006

In this article, a semiclassical, microscopic model (dubbed SMRM) is derived to describe collective rotation in deformed nuclei. The SMRM is derived by transforming the time-dependent, multiparticle Schrodinger equation to a rotating frame whose axes are chosen to coincide with the principal axes of the expectation value of an arbitrary, second-rank, symmetric, tensor (nuclear shape) operator [Formula: see text]. This transformation circumvents the difficulty associated with the introduction of redundant particle coordinates in the Villars' transformation. The SMRM Schrodinger equation, which resembles the cranking model (CM) equation, is a time-dependent, time-reversal-invariant, nonlinear integro-differential equation. In this equation, the angular velocity is determined by the wave function and deformation–rotation shear operators, and this introduces the nonlinearity in the equation. A variational method is proposed and justified to obtain: a stationary solution of the SMRM Schrodinger equation in the Rayleigh–Ritz Hartree–Fock particle–hole formalism, the rotational energy increment, and the associated moment of inertia. When exchange interaction terms are neglected or a separable interaction is used, the SMRM moment of inertia is shown to reduce to that given by the CM provided that a certain relationship exists between the moment of inertia and the expectation value of [Formula: see text]. However, the SMRM and CM wave functions are not the same (SMRM preserves and CM violates time-reversal invariance) implying that the calculated values of other parameters, including the moment of inertia at higher values of the angular momentum, may not be the same in the two models. In any case, the SMRM derives the CM moment of inertia from a microscopic, time-reversal invariant, nonlinear theory.PACS Nos.: 21.60.Ev, 21.60.Fw, 21.60.Jz
The Darboux coordinate system and Holstein–Primakoff representations on Kähler manifolds
Authors: Schmidt J R
Published: November 2006

The Kahler geometry of minimal coadjoint orbits of classical Lie groups is exploited to construct Darboux coordinates, a symplectic two-form and a Lie–Poisson structure on the dual of the Lie algebra. Canonical transformations cast the generators of the dual into Dyson or Holstein–Primakoff representations.PACS Nos.: 02.20.Sv, 02.30.Ik, 02.40.Tt
Classical simulation of quantum fields II
Authors: Hirayama T , Holdom B , Koniuk R , Yavin T
Published: November 2006

We consider the classical time evolution of a real scalar field in two-dimensional Minkowski space with a [Formula: see text] interaction. We compute the spatial and temporal two-point correlation functions and extract the renormalized mass of the interacting theory. We find our results are consistent with the one- and two-loop quantum computation. We also perform Monte Carlo simulations of the quantum theory and conclude that the classical scheme is able to produce more accurate results with a fraction of the CPU time.

PACS Nos.: 03.70.+k, 03.50.–z, 11.15.Tk
Classical simulation of quantum fields I
Authors: Hirayama T , Holdom B
Published: November 2006

We study classical field theories in a background field configuration where all modes of the theory are excited, matching the zero-point energy spectrum of quantum field theory. Our construction involves elements of a theory of classical electrodynamics by Wheeler–Feynman and the theory of stochastic electrodynamics of Boyer. The nonperturbative effects of interactions in these theories can be very efficiently studied on the lattice. In [Formula: see text] theory in 1 + 1 dimensions, we find results, in particular, for mass renormalization and the critical coupling for symmetry breaking that are in agreement with their quantum counterparts. We then study the perturbative expansion of the n-point Green's functions and find a loop expansion very similar to that of quantum field theory. When compared to the usual Feynman rules, we find some differences associated with particular combinations of internal lines going on-shell simultaneously.

PACS Nos.: 03.70.+k, 03.50.–z, 11.15.Tk
Characterization of NOM and its adsorption by iron oxide coated sand (IOCS) using UV and fluorescence spectroscopy
Authors: Li Chi-Wang , Benjamin Mark M , Korshin Gregory V
Published: November 2006

The removal of natural organic matter (NOM) by adsorption onto iron oxide coated sand (IOCS) can be interpreted based on analysis of the absorbance and fluorescence spectra of the water before and after treatment. The useful spectral parameters include SUVA254, the widths of the benzenoid and electron transfer absorbance bands (WBz, and WET, respectively), the ratio of the absorbance intensities of these two bands (AET/ABz), and the wavelength of the emission maximum (λmaxem). These parameters appear to reflect both the activated aromatic content in the sample and its average molecular weight, and are good indicators of the adsorbability of NOM onto IOCS. A multi-parametric spectroscopic approach for online monitoring of NOM and its reactions can be valuable for both practical treatment studies and for fundamental explorations of NOM reactivity. Key words: natural organic matter, UV absorbance, adsorption, activated aromatics.
Triclosan inhibition of membrane enzymes and glycolysis of Streptococcus mutans in suspensions and biofilms
Authors: Phan Tuan-Nghia , Marquis Robert E
Published: November 2006

Triclosan was found to be a potent inhibitor of the F(H+)-ATPase of the oral pathogen Streptococcus mutans and to increase proton permeabilities of intact cells. Moreover, it acted additively with weak-acid transmembrane proton carriers, such as fluoride or sorbate, to sensitize glycolysis to acid inhibition. Even at neutral pH, triclosan could inhibit glycolysis more directly as an irreversible inhibitor of the glycolytic enzymes pyruvate kinase, lactic dehydro genase, aldolase, and the phosphoenolpyruvate:sugar phosphotransferase system (PTS). Cell glycolysis in suspensions or biofilms was inhibited in a pH-dependent manner by triclosan at a concentration of about 0.1 mmol/L at pH 7, approximately the lethal concentration for S. mutans cells in suspensions. Cells in intact biofilms were almost as sensitive to triclosan inhibition of glycolysis as were cells in suspensions but were more resistant to killing. Targets for irreversible inhibition of glycolysis included the PTS and cytoplasmic enzymes, specifically pyruvate kinase, lactic dehydrogenase, and to a lesser extent, aldolase. General conclusions are that triclosan is a multi-target inhibitor for mutans streptococci, which lack a triclosan-sensitive FabI enoyl-ACP reductase, and that inhibition of glycolysis in dental plaque biofilms, in which triclosan is retained after initial or repeated exposure, would reduce cariogenicity.Key words: triclosan, oral streptococci, glycolysis, biofilms, F-ATPase.
Critical period of interspecific competition for four northern conifers: 10-year growth response and associated vegetation dynamics
Authors: Wagner Robert G , Robinson Andrew P
Published: November 2006

The influence of the timing and duration of interspecific competition on planted jack pine (Pinus banksiana Lamb.), red pine (Pinus resinosa Ait.), eastern white pine (Pinus strobus L.), and black spruce (Picea mariana (Mill.) BSP) was assessed using 10-year growth responses in a northern Ontario experiment. Stand volume was 117%, 208%, 224%, and 343% higher for jack pine, red pine, white pine, and black spruce, respectively, with 5 years of vegetation control than with no vegetation control. Stand volume increased linearly with number of years of vegetation control, and the slope of the relationship varied among conifer species. Change-point regression analysis was used to derive segmented weed-free and weed-infested curves, and to simultaneously estimate key critical-period parameters. Weed-free and weed-infested curves in the 10th year were similar to those derived in year 5, indicating that the patterns established during the first few years after planting were relatively robust for the first decade. The critical-period was 2 and 3 years after planting for jack pine and red pine, respectively, and occupied most of the 5-year period for white pine and black spruce. Principal components analysis of the vegetation community indicated that repeated herbicide applications caused differential shifts in the relative abundance of shrub, fern, and moss species through the 10th year. Species richness, however, was not substantially different between the untreated control and the most intensive treatments. Difference modeling was used to quantify how annual volume increment during the first decade varied with time, conifer species, cover of woody and herbaceous vegetation, and stage of development.
Fate of the herbicide sulfometuron methyl (Oust®) and effects on invertebrates in drainages of an intensively managed plantation
Authors: Michael J L , Batzer D P , Fischer J B , Gibbs H L
Published: November 2006

The off-site movement and impacts on water quality and aquatic ecosystems of sulfometuron methyl applied as the herbicide Oust® to catchments in short-rotation plantations in the coastal plain of South Carolina were studied. Sulfometuron methyl was applied at the rate of 0.053 kg active ingredient·ha–1 to 5.4- and 5.9-ha catchments (C5 and C6, respectively). Off-site movement of sulfometuron methyl in drainage ditches was observed between application on 14 March 2001 and 14 June 2001 for the first five flow-producing rain events on C5 and the first four events on C6. The maximum observed concentrations (24 µg·L–1 on C5 and 23 µg·L–1 on C6) occurred during the first storm. Subsequent maximum concentrations for flow-producing storms were 10.0, 5.0, 0.5, and 0.1 µg·L–1 on C5 and 15.1, 6.7, and 0.5 µg·L–1 on C6. Pulsed inputs of sulfometuron methyl to stormflow were ephemeral and the maximum concentration for each storm event lasted 15 min or less. The faunal communities observed in these drainage ditches were dominated by a diversity of invertebrates typical of wetland habitats, such as midges, mosquitoes, water beetles, physid snails, and water fleas. Negative effects of sulfometuron methyl treatment on these communities in treated watersheds were not observed.
Modeling dynamics of competing vegetation in young conifer plantations of northern California and southern Oregon, USA
Authors: Ritchie Martin W , Hamann Jeff D
Published: November 2006

This paper describes the development of growth equations for competing vegetation in young conifer plantations, consistent with an individual-tree growth model architecture. Response variables were height increment, basal diameter increment, and change in crown width for a 2-year growth interval. The results for three common competing shrub and three competing hardwood species are presented. Fit statistics for hardwoods were generally much better than those obtained for shrub species. Crown width growth equations generally had very poor fit statistics. Static crown equations also relate crown area to plant height. The equations were developed for use in an individual-tree plant growth model for young plantations.
The spatial influence of Pseudotsuga menziesii retention trees on ectomycorrhiza diversity
Authors: Luoma Daniel L , Stockdale Christopher A , Molina Randy , Eberhart Joyce L
Published: November 2006

Living retention trees are being used in managed forests to promote a variety of values, including the maintenance of biological diversity. Federal forest plans for the northwestern USA include guidelines that require the retention of a minimum of 15% basal area in harvest units, with the goal of facilitating the development of late-seral stand structure, which is an important habitat element for old-growth forest-dependent species. However, effective levels and patterns of green-tree retention are unknown. We present results of a treatment consisting of 15% basal area, evenly dispersed retention (15%D). We quantified changes in the ectomycorrhiza (EM) community after the 15%D treatment, both near and away from retention trees. Pretreatment samples were obtained between 1 and 24 months before tree harvest. Post-treatment samples were collected within 14–25 months of harvest. In areas 8–25 m from retention trees, there was a 50% decline in the number of EM types per soil core from before to after treatment. Soil cores taken >5 m from retention trees exhibited a shift in EM community structure. EM-type richness was positively correlated with fine-root-tip density. We demonstrate the potential for retention trees to act as refugia for recolonization of newly established seedlings by ectomycorrhizal fungi.
The sawmill industry of the Lake States: a study of productivity, technological change, and factor demand
Authors: McQueen James RG , Potter-Witter Karen
Published: November 2006

A translog variable cost function of the sawmill industry in Michigan, Minnesota, and Wisconsin was estimated using pooled time-series data for the period 1963–1996 with inputs labour, materials, and capital. The estimated model imposed Hicks-neutral technical change and allowed for nonconstant returns to scale as well as nonunitary elasticities of substitution amongst the inputs. Results for the Allen–Uzawa partial elasticity of substitution and the Morishima elasticity of substitution indicate that the three inputs were inelastic substitutes. The own-price elasticities of demand and the cross-price elasticities were all inelastic. The industry exhibits increasing returns to scale and positive technical change. Total factor productivity was increasing by 0.69%/year over the study period.
Influence d'une hydromorphie modérée ou sévère sur la production de biomasse et les échanges gazeux de plants de peuplier euraméricain
Authors: Béjaoui Zoubeir , Albouchi Ali , Abassi Mejda , Aouni Mohamed Hédi El
Published: November 2006

Seedlings of three poplar clones (I-488, Rimini, and D-64) grown in plastic pots were submitted to three water regimes: (1) irrigated and well-drained control (T); (2) flooded with running water (Hr = 6 mg·L–1 of O2); and (3) flooded with stagnant water (Hs = 2 mg·L–1 of O2). A permanent water table was maintained at 5 cm above the soil surface for 2 months. The Hr and Hs treatments simulate the conditions of hydromorphic soils chosen for planting poplar in Tunisia where the attempts failed because of the lack of knowledge relating to the degree of tolerance of this species to waterlogging. Waterlogging significantly reduced growth (leaf initiation was inhibited, root decay and early leaf abscission occurred) and modified photosynthetic activity (stomatal closure and reduction of CO2 net assimilation rates). Intracellular CO2 values did not significantly differ between treatments (T, Hr, and Hs), indicating that both stomatal and nonstomatal limitations could be responsible for reducing CO2 net assimilation. However, the degree of disruption varied according to the treatment. Stagnant regime Hs had negative and irreversible effects on CO2 net assimilation rates and internal CO2 conductance for the full length of the treatments with stomatal closure after 40 days in Rimini and D-64 clones. The Hr treatment produced limited reactions; the development of hypertrophied lenticels and adventitious roots alleviated the negative effects of waterlogging with a distinct recuperation of net photosynthesis and CO2 internal conductance particularly for clone I-488. In the same way, the development of root adaptations was greater for I-488 than Rimini and D-64 clones, probably indicating a higher tolerance to flooding in the former clone. This approach could be used to select the clones intended for afforestation of the nonsaline hydromorphic areas.
Quantity and decay stages of coarse woody debris in old-growth subalpine spruce forests of the western Carpathians, Poland
Authors: Zielonka Tomasz
Published: November 2006

The amount and decay stages of dead wood and the residence time of logs was studied in old-growth spruce-dominated stands in the Tatra and Babia Góra in the western Carpathian Mountains in Central Europe. The DBH of living trees and snags as well as the dimensions of logs (with a minimum diameter of 10 cm) were measured on nine sample plots with a pooled area of 4.3 ha. For the logs, the decay stage was identified according to an eight-level decay classification. Dendrochronological cross-dating was applied to 107 wood samples of logs to determine the time since death. The average volume of living trees was 454 m3/ha and the volume of coarse woody debris (CWD) averaged 191 m3/ha. The noted volume of CWD was higher than volumes reported from previous studies in the Carpathian Mountains. On average, CWD made up 30% of the total volume (living plus dead) and varied between 49% and 21% for the stands. The average age of logs for decay class 1 was 13 years and 24, 28, 38, 45, 38, and 60 years for decay classes 2–7, respectively. Considerable variation of time since death between decay classes was probably due to a variable time while dead trees remained standing as snags.
Overstory and understory development in thinned and underplanted Oregon Coast Range Douglas-fir stands
Authors: Chan Samuel S , Larson David J , Maas-Hebner Kathleen G , Emmingham William H , Johnston Stuart R , Mikowski Daniel A
Published: November 2006

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests managed for timber in western Oregon frequently lack structure and diversity associated with old-growth forests. We examined thinning effects on overstory and understory development for 8 years after treatment. Three 30- to 33-year-old Oregon Coast Range plantations were partitioned into four overstory treatments: unthinned (~550 trees/ha) and lightly (~250 trees/ha), moderately (~150 trees/ha), and heavily (~75 trees/ha) thinned. Within each overstory treatment, two understory treatments were established: underplanted with Douglas-fir and western hemlock (Tsuga heterophylla (Raf.) Sarg.) or not underplanted. Thinning increased overstory stem growth, crown expansion, and retained crown length. Thinned overstory canopies began to close rapidly the third year after thinning, decreasing % skylight by approximately 2%/year, whereas % skylight in unthinned stands increased slightly. All seedlings planted in unthinned stands died, whereas eighth year survival in thinned stands averaged 88%. Natural regeneration densities and distributions were highly variable. Understory shrub cover was reduced by harvesting disturbance but recovered by the fifth year. Thinning increased understory plant species diversity, and no shrub species were lost. Thinning to low densities and underplanting has the potential to accelerate development of multilayered stands characteristic of old-growth Douglas-fir forests.
Twenty year responses of white spruce to mechanical site preparation and early chemical release in the boreal region of northeastern British Columbia
Authors: Boateng Jacob O , Heineman Jean L , McClarnon John , Bedford Lorne
Published: November 2006

The effects of six mechanical site preparation treatments, two stock-type treatments, and early chemical release on survival and growth of planted white spruce (Picea glauca (Moench) Voss) were studied in the BWBSmw1 biogeoclimatic zone of northeastern British Columbia. After 20 years, spruce height and diameter were larger in all mounding treatments than in the control. Early results suggested better spruce performance on large than small mounds, but after 20 years, growth was equally good on small mounds as on mounds with 20 cm mineral capping. Spruce planted on hinge positions in the Bräcke patch and blade scarification treatments did not survive or grow well. Early chemical release improved spruce growth equally as well as the mounding treatments. Twenty year spruce survival averaged 71% in the 14 and 20 cm mound treatments, 60% in the early chemical release treatment, and ≤35% in the Bräcke patch and blade scarification treatments. A large stock type was also planted in untreated ground and, after 20 years, had similar survival and growth as the standard stock type. Differences in survival had a large effect on basal area at age 20 years. Trend analysis showed that treatments diverged into two distinct groups with regard to spruce size during the 20 year span of the study.
DYONS OF ONE-HALF MONOPOLE CHARGE
Authors: TEH ROSY , WONG KHAI-MING
Published: November 2006

We would like to present some exact SU(2) Yang–Mills–Higgs dyon solutions of one-half monopole charge. These static dyon solutions satisfy the first order Bogomol'nyi equations and are characterized by a parameter, m. They are axially symmetric. The gauge potentials and the electromagnetic fields possess a string singularity along the negative z-axis and hence they possess infinite energy density along the line singularity. However the net electric charges of these dyons which varies with the parameter m are finite.
MUON ANOMALY AND A LOWER BOUND ON HIGGS MASS DUE TO A LIGHT STABILIZED RADION IN THE RANDALL–SUNDRUM MODEL
Authors: DAS PRASANTA KUMAR
Published: November 2006

We investigate the Randall–Sundrum model with a light stabilized radion (required to fix the size of the extra dimension) in the light of muon anomalous magnetic moment [Formula: see text]. Using the recent data (obtained from the E821 experiment of the BNL Collaboration) which differs by 2.6σ from the Standard Model result, we obtain constraints on radion mass mϕ and radion vacuum expectation value 〈ϕ〉. In the presence of a radion the beta functions β(λ) and β(gt) of Higgs quartic coupling (λ) and top-Yukawa coupling (gt) gets modified. We find these modified beta functions. Using these beta functions together with the anomaly constrained mϕ and 〈ϕ〉, we obtain lower bound on Higgs mass mh. We compare our result with the present LEP2 bound on mh.
LIGHT SUPERPARTNERS AT HADRON COLLIDERS
Authors: YU. BOGACHEV D. , GLADYSHEV A. V. , KAZAKOV D. I. , NECHAEV A. S.
Published: November 2006

Uncertainties of the MSSM predictions are due to an unknown SUSY breaking mechanism. To reduce these uncertainties, one usually imposes constraints on the MSSM parameter space. Recently, two new constraints became available, both from astrophysics: WMAP precise measurement of the amount of the Dark Matter in the Universe and EGRET data on an excess in diffuse gamma ray flux. Being interpreted as a manifestation of supersymmetry these data lead to severe constraints on parameter space and single out a very restricted area. The key feature of this area is the splitting of light gauginos from heavy squarks and sleptons. We study the phenomenological properties of this scenario, in particular, the cross-sections of superparticle production, their decay patterns and signatures for observation at hadron colliders, Tevatron and LHC. We found that weakly interacting particles in this area are very light so that the cross-sections may reach fractions of a pb with jets and/or leptons as final states accompanied by missing energy taken away by light neutralino with a mass around 100 GeV.
MEAN FIELD MODEL OF THE GENETIC TOGGLE SWITCH
Authors: ANDRECUT M. , KAUFFMAN S. A.
Published: November 2006

In this paper we discuss a noisy mean field model for the genetic toggle switch. We show that this model approximates very well the characteristics of the system, observed using the exact Gillespie stochastic simulation algorithm. Also, we show that the system can be made exponentially stable depending on reaction parameters.
DEVELOPMENT OF A FRAMEWORK FOR WORLD-CLASS MAINTENANCE SYSTEMS
Authors: MISHRA RAJESH PRASAD , ANAND G. , KODALI RAMBABU
Published: November 2006

A world-class maintenance system (WMS) refers to the best practices in maintenance that are followed and adopted by various organizations to transform themselves to be a 'world-class manufacturer'. One of the important factors in developing a 'world-class' maintenance system within an organization is the adoption of a sound framework that provides the necessary conceptual and theoretical details of best practices to be followed, to reach the world-class status. Several authors, consultants and large organizations have proposed different frameworks representing the best practices in maintenance, which seem to have been developed and derived primarily from the context and experience of such large organizations and consultants respectively. A comparative study revealed that most of the frameworks are unique and proposes several unique best practices in maintenance. Hence, in this paper, an attempt has been made to identify such best practices from the existing frameworks and integrate these practices to develop and propose a new framework for world-class maintenance systems.
COMPARATIVE GENOMICS OF TRANSCRIPTIONAL REGULATION IN YEASTS AND ITS APPLICATION TO IDENTIFICATION OF A CANDIDATE ALPHA-ISOPROPYLMALATE TRANSPORTER
Authors: KOVALEVA GALINA YU. , BAZYKIN GEORGII A. , BRUDNO MICHAEL , GELFAND MIKHAIL S.
Published: November 2006

Conservation rates in non-protein-coding regions of five yeast genomes of the genus Saccharomyces were analyzed using multiple whole-genome alignments. This analysis confirmed previously shown decrease in conservation rates observed immediately upstream of the translation start point and downstream of the stop-codon. Further, there was a sharp conservation peak in the upstream regions likely related to the core promoter (-35 bp to +35 bp around TSS) and a conservation peak downstream of the stop-codon whose function is not yet clear. Regulation of leucine and methionine biosynthesis controlled by the global regulator Gcn4p and pathway-specific regulators was analyzed in detail. A candidate alpha-isopropylmalate carrier, YOR271cp, was identified based on conservation of Leu3p binding sites, analysis of ChIP-chip data, protein localization and sequence similarity.
New Challenges for Telephone Survey Research in the Twenty-First Century
Authors: Kempf Angela M. , Remington Patrick L.
Published: November 2006

Telephone surveys are critical for examining cross-sectional characteristics of population subgroups, tracking trends in prevalence of conditions and risk behaviors over time, identifying risk factors associated with multiple health conditions, and assessing the effects of interventions. Technology has aided telephone research through advances such as computer-assisted telephone interviewing. However, technology such as answering machines and caller ID has contributed to declines in response rates and has increased costs of conducting telephone surveys. The exponential increase in cell phone utilization presents a challenge to the tradition of random digit dial (RDD) surveys of households. Because telephone surveys are used by other industries such as marketing and public opinion polling, the marketplace may help drive innovation and adaptation. Cell phones have made telephone communication an even greater part of the everyday culture and could make potential telephone survey respondents even more accessible to public health researchers.
Hypertonic induction of aquaporin-5: novel role of hypoxia-inducible factor-1α
Authors: Zhou Beiyun , Ann David K. , Li Xian , Kim Kwang-Jin , Lin Helen , Minoo Parviz , Crandall Edward D. , Borok Zea
Published: November 2006

Aquaporin-5 (AQP5) is a water channel protein expressed on the apical surface of alveolar epithelial type I cells in distal rat lung, suggesting a role for AQP5 in regulating alveolar surface liquid tonicity and/or cell volume. We investigated the molecular mechanisms underlying hypertonic induction of AQP5 in primary rat alveolar epithelial cells (AEC). Steady-state levels of AQP5 mRNA and protein were increased by exposure to sorbitol (200 mM in culture fluid) for 24 h. The increase in AQP5 was not accompanied by changes in mRNA half-life. Transduction of mouse lung epithelial (MLE-15) cells and primary rat AEC with lentivirus vectors encoding AQP5-luciferase demonstrated transcriptional activation of the reporter by exposure to hypertonic sorbitol solution. Hybridization of proteins from sorbitol-treated cells to a transcription factor DNA array demonstrated induction of hypoxia-inducible factor-1α (HIF-1α) by hypertonicity, which was confirmed by quantitative RT-PCR. Cotransfections of AQP5-luciferase with HIF-1α and HIF-1β expression plasmids in MLE-15 cells led to dose-dependent transcriptional enhancement, which was partially abrogated by mutagenesis of putative HIF-1α binding sites in the proximal AQP5 promoter. Importantly, hypertonic induction of AQP5 was significantly inhibited by preventing HIF-1α induction with small interfering RNA. Hypertonicity induced activation of a transiently transfected vascular endothelial growth factor (VEGF) hypoxia response element-driven luciferase construct and increased expression of endogenous VEGF. These results demonstrate that hypertonic induction of both AQP5 and VEGF is transcriptionally regulated and mediated, at least in part, by HIF-1α, suggesting a novel role for HIF-1α in modulating cellular adaptive responses to osmotic stress.
Enhanced cadmium-induced testicular necrosis and renal proximal tubule damage caused by gene-dose increase in aSlc39a8-transgenic mouse line
Authors: Wang Bin , Schneider Scott N. , Dragin Nadine , Girijashanker Kuppuswami , Dalton Timothy P. , He Lei , Miller Marian L. , Stringer Keith F. , Soleimani Manoocher , Richardson Douglas D. , Nebert Daniel W.
Published: November 2006

Resistance to cadmium (Cd)-induced testicular necrosis is an autosomal recessive trait defined as the Cdm locus. Using positional cloning, we previously identified the Slc39a8 (encoding an apical-surface ZIP8 transporter protein) as the gene most likely responsible for the phenotype. In situ hybridization revealed that endothelial cells of the testis vasculature express high ZIP8 levels in two sensitive inbred mouse strains and negligible amounts in two resistant strains. In the present study, we isolated a 168.7-kb bacterial artificial chromosome (BAC), carrying only the Slc39a8 gene, from a Cd-sensitive 129/SvJ BAC library and generated BAC-transgenic mice. The BTZIP8-3 line, having three copies of the 129/SvJ Slc39a8 gene inserted into the Cd-resistant C57BL/6J genome (having its normal two copies of the Slc39a8 gene), showed tissue-specific ZIP8 mRNA expression similar to wild-type mice, mainly in lung, testis, and kidney. The ∼2.5-fold greater expression paralleled the fact that the BTZIP8-3 line has five copies, whereas wild-type mice have two copies, of the Slc39a8 gene. The ZIP8 mRNA and protein localized especially to endothelial cells of the testis vasculature in BTZIP8-3 mice. Cd treatment reversed Cd resistance (seen in nontransgenic littermates) to Cd sensitivity in BTZIP8-3 mice; reversal of the testicular necrosis phenotype confirms that Slc39a8 is unequivocally the Cdm locus. ZIP8 also localized specifically to the apical surface of proximal tubule cells in the BTZIP8-3 kidney. Cd treatment caused acute renal failure and signs of proximal tubular damage in the BTZIP8-3 but not nontransgenic littermates. BTZIP8-3 mice should be a useful model for studying Cd-induced disease in kidney.
Mechanisms of secretion-associated shrinkage and volume recovery in cultured rabbit parietal cells
Authors: Bachmann Oliver , Heinzmann Alexander , Mack Andreas , Manns Michael P. , Seidler Ursula
Published: November 2006

We have previously shown that stimulation of acid secretion in parietal cells causes rapid initial cell shrinkage, followed by Na+/H+ exchange-mediated regulatory volume increase (RVI). The factors leading to the initial cell shrinkage are unknown. We therefore monitored volume changes in cultured rabbit parietal cells by confocal measurement of the cytoplasmic calcein concentration. Although blocking the presumably apically located K+ channel KCNQ1 with chromanol 293b reduced both the forskolin- and carbachol-induced cell shrinkage, inhibition of Ca2+-sensitive K+ channels with charybdotoxin strongly inhibited the cell volume decrease after carbachol, but not after forskolin stimulation. The cell shrinkage induced by both secretagogues was partially inhibited by blocking H+-K+-ATPase with SCH28080 and completely absent after incubation with NPPB, which inhibits parietal cell anion conductances involved in acid secretion. The subsequent RVI was strongly inhibited with the Na+/H+ exchanger 1 (NHE1)-specific concentration of HOE642 and completely by 500 μM dimethyl-amiloride (DMA), which also inhibits NHE4. None of the above substances induced volume changes under baseline conditions. Our results indicate that cell volume decrease associated with acid secretion is dependent on the activation of K+ and Cl− channels by the respective secretagogues. K+, Cl−, and water secretion into the secretory canaliculi is thus one likely mechanism of stimulation-associated cell shrinkage in cultured parietal cells. The observed RVI is predominantly mediated by NHE1.
Origin of spontaneous activity in neonatal and adult rat bladders and its enhancement by stretch and muscarinic agonists
Authors: Kanai A. , Roppolo J. , Ikeda Y. , Zabbarova I. , Tai C. , Birder L. , Griffiths D. , de Groat W. , Fry C.
Published: November 2006

This study examined the origin of spontaneous activity in neonatal and adult rat bladders and the effect of stretch and muscarinic agonists and antagonists on spontaneous activity. Rats were anesthetized and their bladders were excised, cannulated, and loaded with voltage- and Ca2+-sensitive dyes. Intracellular Ca2+ and membrane potential transients were mapped using photodiode arrays in whole bladders, bladder sheets, or cross-section preparations at 37°C. Intravesical pressure was recorded from whole bladders. In neonatal bladders and sheets, spontaneous Ca2+ and electrical signals arose at a site near the dome and spread in a coordinated manner throughout the bladder with different dome-to-neck conduction velocities (Ca2+: 3.7 ± 0.4 mm/s; membrane potential: 46.2 ± 3.1 mm/s). In whole bladders, optical signals were associated with spontaneous contractions (10–20 cmH2O). By contrast, in adult bladders spontaneous Ca2+ and electrical activity was uncoordinated, originating at multiple sites and was associated with smaller (2–5 cmH2O) contractions. Spontaneous contractions and optical signals were insensitive to tetrodotoxin (2 μM) but were blocked by nifedipine (10 μM). Stretch or low carbachol concentrations (50 nM) applied to neonatal whole bladders enhanced the amplitude (to 20–35 cmH2O) of spontaneous activity, which was blocked by atropine. Bladder cross sections revealed that Ca2+ and membrane potential transients produced by stretch or carbachol began near the urothelial-suburothelial interface and then spread to the detrusor. In conclusion, spontaneous activity in neonatal bladders, unlike activity in adult bladders, is highly organized, originating in the urothelium-suburothelium near the dome. Activity is enhanced by stretch or carbachol and this enhancement is blocked by atropine. It is hypothesized that acetylcholine is released from the urothelium during bladder filling to enhance spontaneous activity.
Neural Responses to Facial Expression and Face Identity in the Monkey Amygdala
Authors: Gothard K. M. , Battaglia F. P. , Erickson C. A. , Spitler K. M. , Amaral D. G.
Published: November 2006

The amygdala is purported to play an important role in face processing, yet the specificity of its activation to face stimuli and the relative contribution of identity and expression to its activation are unknown. In the current study, neural activity in the amygdala was recorded as monkeys passively viewed images of monkey faces, human faces, and objects on a computer monitor. Comparable proportions of neurons responded selectively to images from each category. Neural responses to monkey faces were further examined to determine whether face identity or facial expression drove the face-selective responses. The majority of these neurons (64%) responded both to identity and facial expression, suggesting that these parameters are processed jointly in the amygdala. Large fractions of neurons, however, showed pure identity-selective or expression-selective responses. Neurons were selective for a particular facial expression by either increasing or decreasing their firing rate compared with the firing rates elicited by the other expressions. Responses to appeasing faces were often marked by significant decreases of firing rates, whereas responses to threatening faces were strongly associated with increased firing rate. Thus global activation in the amygdala might be larger to threatening faces than to neutral or appeasing faces.
Lack of Adaptation to Random Conflicting Force Fields of Variable Magnitude
Authors: Gupta Rahul , Ashe James
Published: November 2006

The concept of internal models has been used to explain how the brain learns and stores a variety of motor behaviors. A large body of work has shown that conflicting internal models could not be learned simultaneously; this suggests either a limited capacity or the unstable nature of short-term motor memories. However, it has been recently shown that multiple conflicting internal models of motor behavior could be acquired simultaneously if associated with appropriate contextual cues and random presentations. We re-examined this issue in a more complex environment in which the magnitude of the conflicting fields could vary randomly. Human subjects failed to show any evidence of learning the force fields themselves or the magnitude of the forces experienced, even with extended practice. Subjects did adapt to the applied perturbation when the field strength was kept constant but still did not form internal models. Our results show that neither random presentation nor specific contextual cues are sufficient for learning conflicting internal models when the magnitude of the forces is also unpredictable. The data suggest that multiple conflicting internal models cannot be learned in all environments, and provide support for the unstable nature or limited capacity of motor memories.
Failed Excitability of Spinal Motoneurons Induced by Prolonged Running Exercise
Authors: Racinais S. , Girard O. , Micallef J. P. , Perrey S.
Published: November 2006

The main purpose of this study was to investigate the modulations in H-reflex and V-wave responses (spinal loop properties) induced by prolonged locomotion activities. The second purpose was to compare the development of central fatigue between continuous and intermittent running modes. Eleven males randomly performed two 90-min running exercises either continuously (CONT, first ventilatory threshold) or intermittently (INT, 150 s at a velocity 20% higher than that during CONT/30 s of recovery). Neuromuscular tests of the plantar flexors [including M-wave and H-reflex at rest and M-wave and V-wave during maximal voluntary contraction (MVC)] were performed before and 5 and 30 min after the running exercises. During MVC, the torque significantly decreased ( P < 0.05) from preexercise to 5 and 30 min postexercise (−11 and −9%, respectively), as did the RMS/M ratio (−11 and −13%, respectively) and the V/M ratio (−19 and −37%, respectively) for the soleus muscle. At rest, the H/M ratio also decreased significantly ( P < 0.001) from preexercise to 5 and 30 min postexercise (−61 and −55%, respectively). Last, no difference in the alteration of spinal loop properties was noted between CONT and INT. In conclusion, the results regarding H-reflex and V-wave suggest for the first time a modulation in spinal loop properties after prolonged running.
Properties of Action-Potential Initiation in Neocortical Pyramidal Cells: Evidence From Whole Cell Axon Recordings
Authors: Shu Yousheng , Duque Alvaro , Yu Yuguo , Haider Bilal , McCormick David A.
Published: November 2006

Cortical pyramidal cells are constantly bombarded by synaptic activity, much of which arises from other cortical neurons, both in normal conditions and during epileptic seizures. The action potentials generated by barrages of synaptic activity may exhibit a variable site of origin. Here we performed simultaneous whole cell recordings from the soma and axon or soma and apical dendrite of layer 5 pyramidal neurons during normal recurrent network activity (up states), the intrasomatic or intradendritic injection of artificial synaptic barrages, and during epileptiform discharges in vitro. We demonstrate that under all of these conditions, the real or artificial synaptic bombardments propagate through the dendrosomatic-axonal arbor and consistently initiate action potentials in the axon initial segment that then propagate to other parts of the cell. Action potentials recorded intracellularly in vivo during up states and in response to visual stimulation exhibit properties indicating that they are typically initiated in the axon. Intracortical axons were particularly well suited to faithfully follow the generation of action potentials by the axon initial segment. Action-potential generation was more reliable in the distal axon than at the soma during epileptiform activity. These results indicate that the axon is the preferred site of action-potential initiation in cortical pyramidal cells, both in vivo and in vitro, with state-dependent back propagation through the somatic and dendritic compartments.
Increased Nociceptive Input Rapidly Modulates Spinal GABAergic Transmission Through Endogenously Released Glutamate
Authors: Zhou Hong-Yi , Zhang Hong-Mei , Chen Shao-Rui , Pan Hui-Lin
Published: November 2006

Stimulation of nociceptive primary afferents elicits pain by promoting glutamatergic transmission in the spinal cord. Little is known about how increased nociceptive input controls GABAergic tone in the spinal dorsal horn. In this study, we determined how increased nociceptive inflow affects GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) of lamina II neurons by using whole cell recordings in rat spinal cord slices. Bath application of capsaicin for 3 min induced a long-lasting inhibition of sIPSCs in 50% of the neurons tested. In the other half of the neurons, capsaicin either increased the frequency of sIPSCs (34.6%) or had no effect on sIPSCs (15.4%). The GABAAcurrent elicited by puff application of GABA was not altered by capsaicin. Capsaicin did not inhibit sIPSCs in rats treated with intrathecal pertussis toxin. Also, capsaicin failed to inhibit sIPSCs in the presence of ionotropic glutamate receptor antagonists or in the presence of both LY341495 and CPPG (group II and group III metabotropic glutamate receptor antagonists, respectively). However, when LY341495 or CPPG was used alone, capsaicin still decreased the frequency of sIPSCs in some neurons. Additionally, bradykinin significantly inhibited sIPSCs in a population of lamina II neurons and this inhibitory effect was also abolished by LY341495 and CPPG. Our study provides novel information that stimulation of nociceptive primary afferents rapidly suppresses GABAergic input to many dorsal horn neurons through endogenous glutamate and activation of presynaptic group II and group III metabotropic glutamate receptors. These findings extend our understanding of the microcircuitry of the spinal dorsal horn involved in nociception.
Reactive Oxygen Species Mediate Central Cardiorespiratory Network Responses to Acute Intermittent Hypoxia
Authors: Griffioen Kathleen J. S. , Kamendi Harriet W. , Gorini Christopher J. , Bouairi Evguenia , Mendelowitz David
Published: November 2006

Although oxidative stress and reactive oxygen species generation is typically associated with localized neuronal injury, reactive oxygen species have also recently been shown to act as a physiological signal in neuronal plasticity. Here we define an essential role for reactive oxygen species as a critical stimulus for cardiorespiratory reflex responses to acute episodic hypoxia in the brain stem. To examine central cardiorespiratory responses to episodic hypoxia, we used an in vitro medullary slice that allows simultaneous examination of rhythmic respiratory-related activity and synaptic neurotransmission to cardioinhibitory vagal neurons. We show that whereas continuous hypoxia does not stimulate excitatory neurotransmission to cardioinhibitory vagal neurons, acute intermittent hypoxia of equivalent duration incrementally recruits an inspiratory-evoked excitatory neurotransmission to cardioinhibitory vagal neurons during intermittent hypoxia. This recruitment was dependent on the generation of reactive oxygen species. Further, we demonstrate that reactive oxygen species are incrementally generated in glutamatergic neurons in the ventrolateral medulla during intermittent hypoxia. These results suggest a neurochemical basis for the pronounced bradycardia that protects the heart against injury during intermittent hypoxia and demonstrates a novel role of reactive oxygen species in the brain stem.
New approximate solutions per unit of time for periodically
checked systems with different lifetime distributions
Authors: Rodrigues Dias J.
Published: November 2006

Systems with different lifetime distributions, associated with increasing, decreasing, constant, and bathtub-shaped hazard rates, are examined in this paper. It is assumed that a failure is only detected if systems are inspected. New approximate solutions for the inspection period and for the expected duration of hidden faults are presented, on the basis of the assumption that only periodic and perfect inspections are carried out. By minimizing total expected cost per unit of time, on the basis of numerical results and a range of comparisons, the conclusion is drawn that these new approximate solutions are extremely useful and simple to put into practice.