bluuebunny/crossref_metadata_2025 huggingface dataset:
Mold Cooling System Design Using Boundary Element Method
Authors: Kwon T. H.
Published: July 2009

Cooling system design in injection molding industries is of great importance because it significantly affects productivity and the quality of the final part. It would thus be very helpful for mold designers to be able to use a computer aided design tool in determining locations of cooling channels and process conditions to achieve uniform cooling and minimum cooling time. Towards this goal, the Boundary Element Method (BEM) has been applied to develop a system of computer aided cooling system design programs: (a) an interactive design program using a two-dimensional BEM and (b) a cooling analysis program using a three-dimensional BEM. In the present work, the injection molding cooling process is simplified by quasi-steady-state heat transfer in terms of cycle-averaged temperature. In this regard, a cycle-averaged heat transfer coefficient between a mold and polymeric material has been introduced for a cycle-averaged boundary condition. In the present paper, discussion centers on the fundamental modeling of the cooling process and the features of the BEM mold cooling design systems.
An Investigation of the End Milling Process Under Varying Machining Conditions
Authors: Fussell B. K. , Srinivasan K.
Published: July 2009

Varying machining conditions are encountered in adaptively controlled machining situations where operating conditions such as the feedrate and spindle speed are adjusted continuously to achieve desired objectives. Proper design, of constraint-type adaptive control systems in particular, requires models of the milling process mechanics since the milling process is usually part of the feedback loop. The adequacy of available models of milling process mechanics is evaluated here experimentally for many cases of varying machining conditions, including changing axial and radial depths of cut and feedrate. Startup transients in the force as the cutter engages the workpiece are also investigated. The significance of dynamic effects in the milling process and of effects such as runout, for constraint-type adaptive control system design, is then evaluated.
Profile Rolling of Gears: A Boundary Element Analysis
Authors: Chandra A.
Published: July 2009

Profile rolling processes such as those for gears play a very important role in everyday manufacturing. It is demonstrated here that the boundary element method (BEM) can be used to analyze, efficiently and accurately, this class of problems involving both material and geometric nonlinearities, as well as contact boundary conditions. The BEM formulation is capable of using any of a class of combined creep-plasticity-constitutive models with state variables for the description of material behavior. The specific problem considered is plane strain profile rolling of straight-toothed spur gears using the constitutive model originally proposed by Hart. The numerical results obtained from the BEM analysis provide a lot of insights into the process of profile rolling and can become a useful tool in designing these forming processes.
Synthesis of Immiscible Alloys by the Mixalloying Process
Authors: Oktay S. Tu¨rker , Chu Chong N. , Saka Nannaji , Suh Nam P.
Published: July 2009

Dispersed-phase microstructures of the immiscible Pb-Zn, Pb-Zn-Sn and Pb-Al alloys were produced by the Mixalloying Process [1]. The particle size was found to follow the log-normal statistical distribution and the mean particle diameter correlated well with the –3/5th power of the Weber number. Furthermore, computational simulation studies showed that the particle-size distributions became significantly broader due to Stokes coalescence during solidification.
A Variational Method for Evaluating Thrust Bearing Element Load Distribution
Authors: Stango R. J. , Jungmann R. H.
Published: July 2009

A variational method is outlined for computing thrust bearing element loads on the basis of minimizing the potential energy of the system. The problem is formulated in terms of a polynomial displacement assumption for bearing elements. To illustrate the computational procedure, numerical studies are presented for a thrust bearing subjected to a range of load eccentricities. The variational approach is demonstrated to result in an accurate and efficient solution for bearing element load distributions. Excellent agreement is achieved when comparison is made to conventional methods of classical bearing theory for nominal load eccentricities, while superior performance is obtained when load eccentricities are considerably larger. Basic advantages of the variational formulation are discussed and an illustrative problem is presented which demonstrates extended capability of the variational method for examining the load distribution in thrust bearings.
Optimal Contouring Control of Multi-Axial Feed Drive Servomechanisms
Authors: Kulkarni P. K. , Srinivasan K.
Published: July 2009

The capability of multi-axial machine tool feed drives to follow specified trajectories accurately is an important requirement for precision machining and especially so in applications involving high contouring speeds. In current generation machine tools, contouring is achieved by coordinating the commands to the individual feed drives, and implementing closed position loop control for each axis. The present paper deals with the evaluation of a cross-coupled compensator aimed specifically at improving contouring accuracy in multi-axial feed drives. The controller design is formulated as an optimal control problem. The performance index to be minimized weights the contour error explicitly. The controller is evaluated experimentally on a microcomputer controlled two-axis positioning table. Controller performance is evaluated for straight line, cornering and circular contours at feed rates varying from 2.25 m/min to 5.63 m/min. Measures of the steady state and transient contour errors are considered. The experimental results show that the proposed controllers reduce contouring errors considerably as compared to conventional uncoupled control of the multiple axes. The control action of the optimal controller is compared with that of more conventional uncoupled controllers.
Tool Wear Detection Using Time Series Analysis of Acoustic Emission
Authors: Liang S. Y. , Dornfeld D. A.
Published: July 2009

This paper discusses the monitoring of cutting tool wear based on time series analysis of acoustic emission signals. In cutting operations, acoustic emission provides useful information concerning the tool wear condition because of the fundamental differences between its source mechanisms in the rubbing friction on the wear land and the dislocation action in the shear zones. In this study, a signal processing scheme is developed which uses an autoregressive time-series to model the acoustic emission generated during cutting. The modeling scheme is implemented with a stochastic gradient algorithm to update the model parameters adoptively and is thus a suitable candidate for in-process sensing applications. This technique encodes the acoustic emission signal features into a time varying model parameter vector. Experiments indicate that the parameter vector ignores the change of cutting parameters, but shows a strong sensitivity to the progress of cutting tool wear. This result suggests that tool wear detection can be achieved by monitoring the evolution of the model parameter vector during machining processes.
Scallop Removal in Die Milling by Tertiary Cutter Motion
Authors: You S. J. , Eman K. F.
Published: July 2009

The feasibility of a newly proposed method for the removal of cutter marks in die finishing operations has been investigated. The method is based on the superposition of a tertiary motion onto the conventional cutter motions. Path equations that consider motion and geometric variables have been derived and used as a basis for the development of a computer simulation model for generating three-dimensional surface representations. It has been shown that the tertiary motion results in a considerable reduction in the volume of the material in the scallops or blend marks left on the surface.
Effects of Machining Parameters on the Microhardness of Chips
Authors: Jain V. K. , Kumar S. , Lal G. K.
Published: July 2009

It has been found that the shear strain acceleration governs the machining parameters like tool-chip interface temperature, shear angle, tool wear, etc. It is therefore speculated that microhardness of the chips for the same machining conditions but for different shear strain accelerations would be different. To test this hypothesis, experiments have been conducted using mild steel as work material and cemented carbide bits as cutting tools. Experiments were performed in two ways: longitudinal turning and accelerated cutting. Chips were collected at the same machining conditions but at different shear strain acceleration. Microhardness of the chips has been measured using the Leibtz-microhardness tester and the results have been analyzed using a computer program CADEAG-1. Using the responses (i.e., microhardness), mathematical models have been evolved. Effects of different parameters (cutting speed, feed, etc.) on the microhardness of the chips in all the three cases (i.e., longitudinal turning, facing, and taper turning) have been studied. It has been concluded that the microhardness of the chips obtained during accelerated cutting is governed by the shear strain acceleration and its governing parameters.
Modeling and Experimental Analysis of Acoustic Emission from Metal Cutting
Authors: Teti R. , Dornfeld D.
Published: July 2009

Testing parameters characterizing acoustic emission (AE) detected during metal cutting may be theoretically correlated, in a simple manner, to work material properites, cutting conditions, and tool geometry. Experimental results, obtained during turning by different researchers using different AE techniques, are presented and critically assessed with reference to their reciprocal agreement as well as their agreement with theoretical predictions. A review of current methods for AE analysis is also presented and the correlations between different AE parameters and energy and power of the detected signals are reported.
Computer-Aided Wheel Profile Design for Railway Vehicles
Authors: Imtiaz-ul-Haque  , Latimer D. A. , Law E. H.
Published: July 2009

Wheel-rail geometry parameters strongly affect the dynamic performance of rail vehicles through their influence on the interaction forces between the wheel and rail. This paper presents an approach that uses nonlinear programming and optimization methods to systematically design wheel profiles that satisfy dynamic performance and wear constraints for conventional rail vehicles. Theoretical studies conducted to this point indicate this approach to be feasible.
Shaping Silicon Nitride With a Carbon Dioxide Laser by Overlapping Multiple Grooves
Authors: Wallace R. J. , Copley S. M.
Published: July 2009

In this research, the feasibility of shaping Si3N4 by overlapping multiple grooves produced with a continuously operated CO2 laser beam is demonstrated. The relationships of process parameters such as material removal rate and arithmetic average surface roughness to machine parameters such as feed and speed have been investigated. Strategies for laser shaping are discussed and an economic evaluation of laser shaping is presented.
Finite Element Models for Analyzing the Straightening of Steel Seamless Tubes
Authors: Dvorkin E. N. , Medina F. M.
Published: July 2009

An important part of the steel seamless tubes production scheme is the straightening process. Finite element models are developed to analyze the straightening process and to evaluate its effect on the final external collapse pressure of the tubes.
Characteristics of Laminated Sheet Metals in Tensile Deformation
Authors: Omura M. , Tabata T. , Shima S.
Published: July 2009

Deformation behavior of laminated sheet metals is estimated by the upper bound method based on Hill’s plasticity theory for anisotropic materials. The r-value and the stress-strain curve are theoretically derived for the laminated sheet metals whose component metals are combined at arbitrary angles to the rolling direction. Tension tests of the laminated sheet metals which are made by bonding in combinations of mild steel, brass, and aluminum sheet metals are carried out. The experimental results are compared with the theoretical ones. They are in good agreement.
A Computer Aided Design System for Three-Dimensional Compression Mold Heating
Authors: Forcucci S. J. , Kwon T. H.
Published: July 2009

Compression mold processing of composites involves taking the charge through a material dependent temperature and pressure path, inducing thermochemical reactions to cure the charge. While curing, specific uniform temperatures are required for a time, and spatial variation of the cavity surface temperature can lengthen time needed to cure and also cause voids and residual stresses, reducing the quality of the finished part. Towards mold heating design goal of uniform cavity surface temperature, an interactive CAD system for compression mold heating design has been developed. The system accepts a previously defined three dimensional, discretized goemetry and uses a Boundary Element Method (BEM) analysis which includes the effects of long, thin electric resistor heating rods, and is coupled with the CONMIN algorithm for constrained minimization of an objective error function to obtain uniform temperature over the cavity surface. Realistic constraints are featured to insure design feasibility. The problem is organized with design in mind to allow fast, easy redesign and a sensitivity study along with the optimization. The approach used is unique and is the first application of this type of optimization to three dimensional mold heating design. An example of the whole design process including creation, reviewing, optimization, and redesign of curved mold example is presented for results.
Mechanics of stretchable inorganic electronic materials
Authors: Song J. , Jiang H. , Huang Y. , Rogers J. A.
Published: July 2009

Electronic systems that offer elastic mechanical responses to high strain deformation are of growing interest due to their ability to enable new applications whose requirements are impossible to satisfy with conventional wafer-based technologies. This article reviews the mechanics of stretchable inorganic materials on compliant substrates. Specifically, three forms of stretchable structures are reviewed. The first one is stretchable ribbon, which provides one-dimensional stretchability. The second is stretchable nanomembranes, which can be stretched in all directions. The last is a noncoplanar mesh design, which has the advantage of providing large stretchability up to and exceeding 100%. Mechanics models and their comparison to experiment are reviewed for these three cases. Such models provide design guidelines for stretchable electronics.
Internal energy distribution change of sputtered Al atom under several hundreds of eV oxygen ion-beam bombardment by resonant laser ionization sputtered neutral mass spectroscopy
Authors: Hayashi Shun-Ichi , Kubota Naoyoshi
Published: July 2009

It is important to evaluate the internal energy of the sputtered neutral particles to optimize their resonant ionization efficiency. In this study, the internal energy of the sputtered Al atom, especially the ground state P1∕22 and the lowest-lying excited state P3∕22 (112cm−1), was monitored by using resonant laser postionization sputtered neutral mass spectrometry. The results of the authors showed the density of the ground state of the sputtered Al atom drastically decreased due to surface oxidation, as well as the enhancement of the secondary Al+ yield.
Sputter deposition of Al-doped ZnO films with various incident angles
Authors: Sato Yasushi , Yanagisawa Kei , Oka Nobuto , Nakamura Shin-ichi , Shigesato Yuzo
Published: July 2009

Al-doped ZnO (AZO) films were sputter deposited on glass substrates heated at 200 °C under incident angles of sputtered particles at 0° (incidence normal to substrate), 20°, 40°, 60°, and 80°. In the case of normal incidence, x-ray diffraction pole figures show a strong [001] preferred orientation normal to the film surface. In contrast, in the case wherein the incident angles were higher than 60°, the [001] orientation inclined by 25°–35° toward the direction of sputtered particles. Transmission electron microscopy revealed that the tilt angle of the [001] orientation increased with increasing angle of the incident sputtered particles, whereas the columnar structure did not show any sign of inclination with respect to the substrate plane.
Enhancement of Biodiversity and Ecosystem Services by Ecological Restoration: A Meta-Analysis
Authors: Benayas José M. Rey , Newton Adrian C. , Diaz Anita , Bullock James M.
Published: July 2009

Assessing Ecological Restoration

In the wake of the Millennium Ecosystem Assessment, the analysis of ecosystem services, and their relationship to biodiversity, has become one of the most rapidly developing research themes in environmental science. At the same time, ecological restoration is widely being implemented as a response to environmental degradation and biodiversity loss.

Rey Benayas
et al.

(p.
1121
, published online 30 July) link these themes in a meta-analysis of the impacts of ecological restoration actions on provision of ecosystem services and biodiversity conservation. The analysis of 89 published restoration projects worldwide establishes that ecological restoration does, in general, have positive impacts on both biodiversity and provision of ecosystem services. These effects are especially marked in the tropics. Thus, ecological restoration actions may indeed deliver benefits, both in terms of biodiversity conservation and supporting human livelihoods.
Common Regulatory Variation Impacts Gene Expression in a Cell Type–Dependent Manner
Authors: Dimas Antigone S. , Deutsch Samuel , Stranger Barbara E. , Montgomery Stephen B. , Borel Christelle , Attar-Cohen Homa , Ingle Catherine , Beazley Claude , Arcelus Maria Gutierrez , Sekowska Magdalena , Gagnebin Marilyne , Nisbett James , Deloukas Panos , Dermitzakis Emmanouil T. , Antonarakis Stylianos E.
Published: July 2009

Tissue-Specific Control

The effect of genetic variation on gene expression and phenotype among individuals is largely unknown.

Dimas
et al.

(p.
1246
, published online 30 July 2009) show that in humans there are several genes whose allelic expression varies in a tissue-specific manner and are apparently controlled by cis elements. Up to 80% of variants seem to have tissue-specific functions when compared in fibroblasts, as well as B cells and T cells. This variation among regulatory variants correlated with transcript complexity, which suggests that some of the observed regulatory variation is due to genotype-specific use of transcripts and transcription start sites.
Mortality from cancer and other causes in the Balangero cohort of chrysotile asbestos miners
Authors: Pira E , Pelucchi C , Piolatto P G , Negri E , Bilei T , La Vecchia C
Published: July 2009

Objectives:

To provide further information on mortality from cancer and other causes among chrysotile asbestos miners several years after exposure ceased, we updated the analyses from the Balangero mine worker cohort with follow-up to the end of 2003.

Methods:

The cohort included 1056 men, for a total of 34 432 man-years of observation. We obtained employment data from factory personnel records, and ascertained vital status and causes of death through population registers and death certificates from municipal registration offices. We computed expected numbers of deaths and standardised mortality ratios (SMRs) for relevant causes using the province of Turin and national death rates, for each 5-year calendar period and age group.

Results:

We found a significant excess mortality from pleural cancer only (4 deaths, SMR 4.67) and pleural and peritoneal cancers combined (5 deaths, SMR 3.16). All pleural and peritoneal cancer deaths occurred 30 or more years after first exposure. The SMRs were 1.27 for lung cancer (45 deaths), 1.82 for laryngeal cancer (8 deaths) and 1.12 for all cancers (142 deaths). Cumulative dust exposure and the various time factors considered did not show a clear pattern of risk associated with mortality from lung cancer. There were 57 deaths from cirrhosis (SMR 2.94) and 54 from accidents and violence (SMR 1.88). Overall, we observed a total of 590 deaths as compared to 412.9 expected (SMR 1.43).

Conclusions:

This updated analysis, with almost 60% of the cohort having died, confirmed the excess mortality from pleural and peritoneal cancers and from several alcohol-related causes.
AGGREGATION AND CONSENSUS IN MULTIOBJECTIVE AND MULTIPERSON DECISION MAKING
Authors: MATURO ANTONIO , VENTRE ALDO GIUSEPPE SAVERIO
Published: July 2009

The subject of the paper is related with the decision making problems with several objectives and a committee of experts. Models for aggregating opinions of experts and consensus reaching on the alternatives with respect to different objectives are presented. A modeling in a metric space is studied and a game theoretic interpretation is introduced. In this framework a procedure for monitoring and enhancing consensus is considered.
CRISP REPRESENTATIONS AND REASONING FOR FUZZY ONTOLOGIES
Authors: BOBILLO FERNANDO , DELGADO MIGUEL , GÓMEZ-ROMERO JUAN
Published: July 2009

Classical ontologies are not suitable to represent imprecise nor uncertain pieces of information. Fuzzy Description Logics were born to represent the former type of knowledge, but they require an appropriate fuzzy language to be agreed on and an important number of available resources to be adapted. This paper faces these problems by presenting a reasoning preserving procedure to obtain a crisp representation for a fuzzy extension of the logic [Formula: see text] which includes fuzzy nominals and trapezoidal membership functions, and uses Gödel implication in the semantics of fuzzy concept and role subsumption. This reduction makes it possible to reuse a crisp representation language as well as currently available reasoners. Our procedure is optimized with respect to related work, reducing the size of the resulting knowledge base. Finally, we also suggest some further optimizations before applying crisp reasoning.
DIVIDING BY DEMANDING: OBJECT DIVISION THROUGH MARKET PROCEDURES
Authors: HAAKE CLAUS-JOCHEN
Published: July 2009

We discuss a model, in which two agents may distribute finitely many objects among themselves. The conflict is resolved by means of a market procedure. Depending on the specifications, this procedure serves to achieve bargaining solutions such as the discrete Raiffa solution, the Kalai-Smorodinsky solution and the Perles-Maschler solution. The latter is axiomatized using the superadditivity axiom, which in the present context is readily interpreted as resolving a specific source of conflict potential.
CONSUMER MISTAKES IN BERTRAND GAMES
Authors: MCCANNON BRYAN C.
Published: July 2009

The identical agent, identical good Bertrand game is associated with prices at marginal cost — the Bertrand Paradox. If consumers make occasional mistakes I show that the standard Bertrand game gives rise to positive profits and prices above marginal cost. Some firms charge low prices to capture the bulk of the sales while others charge high prices selling to mistaken consumers. Furthermore, with free entry the Diamond Paradox arises; a full measure of the firms choose the monopoly price. As a result, the Diamond Paradox arises in an environment with zero search costs by replacing searching costs with searching errors.
AN n-PERSON RUBINSTEIN BARGAINING GAME
Authors: TORSTENSSON PÄR
Published: July 2009

When Herrero (1985) extends Rubinstein's (1982) alternating-offers bargaining model to the case of three or more players any agreement can be supported as a subgame perfect equilibrium (SPE) outcome, given a sufficiently large discount factor. We show that this is not the case when players demand shares for themselves instead of proposing agreements to each other. Although it is possible to rule out agreements, the majority remains to be SPE outcomes.
Luminall-glutamate enhances duodenal mucosal defense mechanisms via multiple glutamate receptors in rats
Authors: Akiba Yasutada , Watanabe Chikako , Mizumori Misa , Kaunitz Jonathan D.
Published: July 2009

Presence of taste receptor families in the gastrointestinal mucosa suggests a physiological basis for local and early detection of a meal. We hypothesized that luminal l-glutamate, which is the primary nutrient conferring fundamental umami or proteinaceous taste, influences mucosal defense mechanisms in rat duodenum. We perfused the duodenal mucosa of anesthetized rats with l-glutamate (0.1–10 mM). Intracellular pH (pHi) of the epithelial cells, blood flow, and mucus gel thickness (MGT) were simultaneously and continuously measured in vivo. Some rats were pretreated with indomethacin or capsaicin. Duodenal bicarbonate secretion (DBS) was measured with flow-through pH and CO2electrodes. We tested the effects of agonists or antagonists for metabotropic glutamate receptor (mGluR) 1 or 4 or calcium-sensing receptor (CaSR) on defense factors. Luminal l-glutamate dose dependently increased pHiand MGT but had no effect on blood flow in the duodenum. l-glutamate (10 mM)-induced cellular alkalinization and mucus secretion were inhibited by pretreatment with indomethacin or capsaicin. l-glutamate effects on pHiand MGT were mimicked by mGluR4 agonists and inhibited by an mGluR4 antagonist. CaSR agonists acidified cells with increased MGT and DBS, unlike l-glutamate. Perfusion of l-glutamate with inosinate (inosine 5′-monophosphate, 0.1 mM) enhanced DBS only in combination, suggesting synergistic activation of the l-glutamate receptor, typical of taste receptor type 1. l-leucine or l-aspartate had similar effects on DBS without any effect on pHiand MGT. Preperfusion of l-glutamate prevented acid-induced cellular injury, suggesting that l-glutamate protects the mucosa by enhancing mucosal defenses. Luminal l-glutamate may activate multiple receptors and afferent nerves and locally enhance mucosal defenses to prevent subsequent injury attributable to acid exposure in the duodenum.
Organic dust exposure alters monocyte-derived dendritic cell differentiation and maturation
Authors: Poole Jill A. , Thiele Geoffrey M. , Alexis Neil E. , Burrell Angela M. , Parks Conrad , Romberger Debra J.
Published: July 2009

Organic dust exposure in agricultural animal environments results in airway diseases. Dendritic cells (DCs) orchestrate inflammatory immune response in the airways, but little is known about how organic dust affects differentiation and maturation of monocyte-derived immature and mature DCs (iDCs, mDCs). Peripheral blood monocytes were differentiated in vitro into iDCs with granulocyte-macrophage colony stimulating factor + IL-4 (6 days) with and without swine facility organic dust extract (ODE, 0.1%). Unlike control iDCs, ODE-conditioned iDCs maintained key monocyte properties (increased mCD14, increased phagocytic ability) while expressing DC features [increased mCD83, HLA-DR, CD80, CD86, diminished cytokine (TNF-α, IL-6) responsiveness]. At day 6, iDCs were cultured for an additional 48 h ( days 7 and 8) with lipopolysaccharide (LPS) to induce mDCs. ODE-conditioned mDCs maintained high expression of mCD14+ and elevated phagocytosis while their DC features weakened as evidenced by decreased CD11c, CD83, HLA-DR, CD86, and CCR7 expression and reduced lymphocyte-stimulating capacity. Similar results were observed when monocytes were exposed to ODE for only the first 48 h and with ODE depleted of endotoxin. Control iDCs exposed to ODE during the final 2 days of iDC maturation ( days 7 and 8) did not differ from control (no ODE) iDCs in surface marker expression and phagocytic ability, but exhibited enhanced lymphocyte-stimulating capacity. Dust exposure alters monocyte differentiation to iDCs and prevents maturation of iDC to mDCs. The first 48 h of monocyte differentiation appears to be the susceptible period to exposure. Environmental exposures present during early monocyte differentiation may impact the critical balance of DCs in the lung.
Neuromuscular transmission failure and muscle fatigue in ankle muscles of the adult rat after spinal cord injury
Authors: Ollivier-Lanvin Karen , Lemay Michel A. , Tessler Alan , Burns Anthony S.
Published: July 2009

Current evidence suggests that significant morphological changes occur in nerve-muscle connections caudal to spinal cord injury (SCI). To determine whether neuromuscular junction (NMJ) function is compromised after SCI, we investigated the contribution of NMJ failure to hindlimb muscle fatigue in control and spinalized adult rats. Repetitive supramaximal nerve stimulation was applied to two muscle-nerve preparations: medial gastrocnemius (MG)-tibial and tibialis anterior (TA)-peroneal. NMJ transmission failure was evident in control and SCI animals after repetitive stimulation. At 2 wk post-SCI, NMJ transmission failure was greater in SCI animals compared with controls, but the difference was not significant ( P = 0.205 for the MG and P = 0.053 for the TA). At 6 wk post-SCI, there was a significant but small difference in NMJ transmission failure for the TA between control and spinal animals. These results demonstrate that, although there may be a mild decrement in NMJ function, NMJ transmission remains largely intact for supramaximal nerve stimulation.
Systemic hypoxia enhances exercise-mediated bactericidal and subsequent apoptotic responses in human neutrophils
Authors: Wang Jong-Shyan , Chiu Ya-Ting
Published: July 2009

Phagocytosis and oxidative burst are critical host defense mechanisms in which neutrophils clear invading pathogens. Clearing phagocytic neutrophils by triggering apoptosis is an essential process for controlling inflammation. This study elucidates how various exercise bouts with/without hypoxia affected neutrophil bactericidal activity and subsequent apoptosis in humans. Fifteen sedentary males performed six distinct experimental tests in an air-conditioned normobaric hypoxia chamber: two normoxic exercises [strenuous exercise (SE; up to maximal O2consumption) and moderate exercise (ME; 50% maximal O2consumption for 30 min) while exposed to 21% O2], two hypoxic exercises (ME for 30 min while exposed to 12% and 15% O2), and two hypoxic exposures (resting for 30 min while exposed to 12% and 15% O2). The results showed that 1) plasma complement-C3a desArg/C4a desArg/C5a concentrations were increased, 2) expressions of L-selectin/lymphocyte functin-associated antigen-1/Mac-1/C5aR on neutrophils were enhanced, 3) phagocytosis of neutrophils to Esherichia coli and release of neutrophil oxidant products by E. coli were elevated, and 4) E. coli -induced phosphotidylserine exposure or caspase-3 activation of neutrophils were promoted immediately and 2 h after both 12% O2exposure at rest and with ME as well as normoxic SE. Although neither normoxic ME nor breathing 15% O2at rest influenced these complement- and neutrophil-related immune responses, ME at both 12% and 15% O2resulted in enhanced complement activation in the blood, expressions of opsonic/complement receptors on neutrophils, or the bactericidal activity and apoptosis of neutrophils. Moreover, the increased neutrophil oxidant production and apoptosis by normoxic SE and hypoxic ME were ameliorated by treating neutrophils with diphenylene iodonium (a NADPH oxidase inhibitor). Therefore, we conclude that ME at 12–15% O2enhances bactericidal capacity and facilitates the subsequent apoptosis of neutrophils.
No major sex differences in muscle protein synthesis rates in the postabsorptive state and during hyperinsulinemia-hyperaminoacidemia in middle-aged adults
Authors: Smith Gordon I. , Atherton Philip , Reeds Dominic N. , Mohammed B. Selma , Jaffery Hadia , Rankin Debbie , Rennie Michael J. , Mittendorfer Bettina
Published: July 2009

Men have more muscle than women, but most studies evaluating sex differences in muscle protein metabolism have been unable to discern sexual dimorphism in basal muscle protein turnover rates in young and middle-aged adults. We hypothesized that the anabolic response to nutritional stimuli (i.e., amino acids and insulin) would be greater in young/middle-aged men than women. We therefore measured the rates of muscle protein synthesis (MPS) in 16 healthy individuals [8 men and 8 women, matched for age (mean ± SE: 37.7 ± 1.5 yr) and body mass index (25.2 ± 0.7 kg/m2)] after an overnight fast (plasma insulin ∼5 μU/ml and plasma phenylalanine ∼60 μM) and during a hyperinsulinemic-hyperaminoacidemic-euglycemic clamp (plasma insulin ∼28 μU/ml; plasma phenylalanine ∼110 μM; plasma glucose ∼5.4 mM). The rates of MPS were not different between men and women (ANOVA main effect for sex; P = 0.49). During the clamp, the rate of MPS increased by ∼50% ( P = 0.003) with no difference in the increases from basal values between men and women (+0.019 ± 0.004 vs. +0.018 ± 0.010%/h, respectively; P = 0.93). There were also no differences between men and women in the basal concentrations of muscle phosphorylated AktSer473, AktThr308, mTORSer2448, and p70s6kThr389 or in the hyperinsulinemia-hyperaminoacidemia-induced increases in phosphorylation of those signaling elements ( P ≥ 0.25). We conclude that there are no major differences in the rate of MPS and its intracellular control during basal conditions and during hyperinsulinemia-hyperaminoacidema between young and middle-aged adult men and women.
Effects of acute hypoxia and hyperthermia on the permeability of the blood-brain barrier in adult rats
Authors: Natah Sirajedin S. , Srinivasan Sathya , Pittman Quentin , Zhao Zonghang , Dunn Jeff F.
Published: July 2009

Acute mountain sickness (AMS) develops within a few hours after arrival at high altitude and includes headache, anorexia, nausea, vomiting, and malaise. This afflicts 15–25% of the general tourist population at moderate altitudes. High-altitude cerebral edema (HACE) is considered to be the end stage of severe AMS and has been suggested to be a vasogenic edema, raising the possibility that acute hypoxia may increase blood-brain barrier (BBB) permeability. At present, there are no good small-animal models to study this syndrome. We hypothesize 1) that acute hypoxia can damage the BBB and 2) that rat can be used as a model to study hypoxia-induced changes in BBB permeability, especially if hypoxia-induced hypothermia could be minimized with high ambient temperature (HAT). Male Wistar rats were exposed to 1, 2, and 7 days of hypobaric hypoxia (equivalent to 0.5 atm), and changes in the temperature and BBB permeability were studied. The extravasation of endogenous immunoglobulin G, a large molecule, did not increase during room temperature hypoxia but did increase when hypoxia was combined with HAT. Hypoxia caused a significant increase in the leakage of sodium fluorescein (mol wt 376 Da). The expression of endothelial barrier antigen (EBA), a protein associated with the BBB, was reduced to 50% between 24 and 48 h after exposure to hypoxia, and the loss was exacerbated by HAT. The values almost returned to control levels by 7 days, showing adaptation to hypoxia. Hypoxic rats exhibited sodium fluorescein leakage mainly in focal areas in the brain parenchyma. In conclusion, it is possible to have transient BBB damage through exposure to acute hypoxia, and this damage is exacerbated by increasing body temperature to more of a normothermic value.
Stricture Rate after Laparoscopic Roux-en-Y Gastric Bypass with a 21-mm Circular Stapler: The Cleveland Clinic Experience
Authors: Alasfar Fahad , Sabnis Adheesh A. , Liu Rockson C. , Chand Bipan
Published: July 2009

Objective: The objectives of this study were to report the incidence of gastrojejunal anastomic strictures that occurred in laparoscopic Roux-en-Y gastric bypass (LRYGB) surgery and to determine the time course of presentation, associated perioperative factors, and response to balloon dilation. Subjects and Methods: All 126 patients who underwent LRYGB at the Cleveland Clinic Foundation between July 2003 and February 2005 were included. We utilized a transoral 21-mm circular stapler for the gastrojejunostomy. Patients with symptoms of anastomotic strictures underwent upper endoscopy by one surgeon (B.C.). A stricture was defined by the inability to pass a 10-mm gastroscope through the anastomosis. Balloon dilation was performed to 12 mm. Records were analyzed retrospectively and statistical analysis including Pearson χ2 statistics, Fisher’s exact test and Student’s t test were used when appropriate. Results: Symptomatic anastomotic strictures occurred in 29 (23%) patients. All patients presented with nausea, vomiting and dysphagia. The median time to diagnosis was 52 days (25–309 days). Symptoms resolved after one dilation in 25 (86%) of patients. Two and three dilations were required in 1 (3.5%) and 3 (10.5%) of patients, respectively. No patients had complications or required more than 3 dilations. Age, preoperative body mass index (BMI), and intraoperative blood loss did not correlate with stricture formation. Although nonsteroidal anti-inflammatory drugs were used by 46 (41%) of patients after surgery, there was no correlation with stricture formation. Conclusion: Symptomatic anastomotic strictures developed in nearly a quarter of patients who underwent LRYGB utilizing a transoral 21-mm circular stapled gastrojejunal anastomosis. A single endoscopic balloon dilation was usually adequate. Strictures were not predicted by perioperative factors.
Antioxidant Activity of Acanthopanax trifoliatus
Authors: Sithisarn Pongtip , Jarikasem Siripen
Published: July 2009

Objective: The aim of this study was to investigate the antioxidant activity of extracts of various parts of Acanthopanax trifoliatus obtained by different extraction methods. The total phenolic and flavonoid contents of the extracts were also determined. Materials and Methods: The leaves, stems, stem bark, roots and root bark of A. trifoliatus were extracted separately using decoction, maceration and refluxing methods. The extracts were analysed for free-radical-scavenging activity using the 1,1-diphenyl-2-picryl-hydrazyl scavenging assay and the thiobarbituric-acid-reactive substance method for the inhibition of lipid peroxidation of a rat brain homogenate. Total phenolic and total flavonoid contents of the extracts were measured by UV spectrophotometry. Results: The leaf decoction extracts possessed a significantly stronger antioxidant activity as revealed by both methods. Total phenolic and flavonoid contents of the extracts ranged from 2.16 to 21.79 g% chlorogenic acid equivalent and from 0.37 to 9.61 g% rutin equivalent, respectively. Analysis of the leaf decoction extract, which exhibited the most potent antioxidant activity, by thin-layer chromatography revealed flavonoid and polyphenolic compounds corresponding to rutin and chlorogenic acid. Conclusion: The leaf aqueous extracts showed a high level of antioxidative activity and contained high levels of both phenolic and flavonoid compounds. The magnitude of antioxidant activity corresponded with the level of phenolic and flavonoid compounds.
Pregnancy-Induced Acute Intestinal Infarction in a Woman with Chronic Idiopathic Mesenteric Vein Thrombosis under Regular Anticoagulation Treatment
Authors: Chan Chia-Meng , Chen Wei-Lung , Chen Jiann-Hwa , Wu Yung-Lung , Huang Chien-Cheng
Published: July 2009

Objective: We present a case of acute intestinal infarction in a pregnant woman with chronic idiopathic mesenteric vein thrombosis (MVT) under regular anticoagulation treatment. Case Presentation and Intervention: The condition of the 26-year-old woman who was diagnosed with chronic idiopathic MVT after detailed investigation was stable after receiving regular anticoagulation with warfarin. One year later, she presented with a 7-day episode of intermittent epigastric pain. Acute intestinal infarction and concomitant 7-week pregnancy were diagnosed. To preserve her life, a dilation and curettage procedure and emergency laparotomy with bowel resection were performed. Ten days later, she was discharged, having made a good recovery. Conclusion: Although pregnancy was not the primary cause of chronic MVT, it did play a role in inducing the acute intestinal infarction. This case indicates that pregnant patients with known chronic idiopathic MVT should be counseled about the high risk of acute mesenteric thrombosis. This case also serves to remind physicians that there should always be a high level of suspicion of intestinal infarction in patients with an acute abdomen who are in a hypercoagulable state.
The Plasma Level of Brain Natriuretic Peptide Is Increased in Malnourished Hemodialysis Patients
Authors: Chazot Charles , Jean Guillaume , Vo-Van Cyril , Collonge Cecile , Terrat Jean Claude , Vanel Thierry , Lorriaux Christie , Hurot Jean Marc , Charra Bernard
Published: July 2009

Background: In hemodialysis (HD) patients, the plasma brain natriuretic peptide (BNP) level is associated with left ventricular dysfunction and patients’ survival. Malnutrition is common in HD patients, it is associated with inflammation and contributes to the high incidence of cardiovascular (CV) disease in this setting (malnutrition-inflammation-atherosclerosis syndrome). In a cross-sectional study, we assessed the relationship between predialysis plasma BNP level and nutritional markers in chronic HD patients. Methods: Of 210 patients receiving HD treatment in our unit, 51 patients who were treated with three times weekly long-hour HD (5–8 h/session) for at least 6 months (mean age 65.8 ± 15.0 years; F/M ratio 23/28; vintage 71.3 ± 71.9 months; BMI 24.9 ± 5.9; session time 6.9 ± 1.3 h; percentage of diabetic patients 31%) were studied before a mid-week HD session for nutritional markers (plasma albumin 35.3 ± 3.7 g/l; prealbumin 0.36 ± 0.09 g/l; CRP 15.3 ± 14.7 mg/l; nPNA 1.29 ± 0.29 g/kg/day) and plasma BNP (246.9 ± 252.2 ng/l, normal <100 ng/l, Bayer® kit). The interdialytic weight gain was 2.1 ± 1.0 kg. In the last 3 months prior to the commencement of the study, the patients’ dry weight varied by +0.17 ± 1.9 kg. Results: Predialysis plasma BNP levels did not differ according to gender and the presence of diabetes. It was not correlated with age and vintage but was found to be negatively associated with the session time (r = –0.34, p = 0.018). Several nutritional markers were negatively correlated with BNP levels: prealbumin (r = –0.46, p = 0.001), BMI (r = –0.33, p = 0.018), nPNA (r = –0.46, p = 0.002). The plasma albumin relationship with the BNP level was close to significance (p = –0.26, p = 0.070). The 3-month dry weight variation was also negatively correlated with BNP levels (r = –0.34, p = 0.018). With multiple stepwise regression analysis, prealbumin and session time remained significant (respectively p = 0.004 and 0.01). BNP levels were higher in a subgroup of malnourished patients (n = 12) (400 ± 405 vs. 202 ± 166 ng/l, p = 0.03) than in patients who did not meet the malnutrition criteria (34 patients). They were not correlated with CRP levels, interdialytic weight gain, or predialysis MAP. Conclusions: Hence, the plasma BNP level was found to be associated with malnutrition but not with inflammation. This underlines the relationship between nutrition and the CV system in HD patients. The body weight variations associated with malnutrition and the difficulties in assessing and adjusting dry weight may lead to fluid overload, which could explain, in part, these correlations.
Interleukin-10 and Interleukin-6 in Aqueous Humor during Treatment of Vitreoretinal Lymphoma with Intravitreally Injected Methotrexate
Authors: Kawamura Hajime , Yasuda Noriko , Kakinoki Masashi , Sawada Tomoko , Sawada Osamu , Ohji Masahito
Published: July 2009

Objective: To evaluate the effectiveness of measuring anterior chamber interleukin (IL)-10 and IL-6 concentrations during treatment of vitreoretinal lymphoma with intravitreally injected methotrexate. Methods: Two patients (3 eyes) underwent repeated weekly intravitreal injections of methotrexate (400 μg of methotrexate/50 μl) for 6 weeks. We monitored the IL-10 and IL-6 concentrations in the anterior chamber and the IL-10/IL-6 ratio at baseline and at the last injections using a standard enzyme-linked immunoassay. Results: Repeated intravitreal injections of methotrexate reduced the vitreous opacity. The IL-10/IL-6 ratio decreased consistently in conjunction with clearance of the vitreous opacity in all 3 eyes, from 39.2 to 0.02, 1.67 to 0.03 and 3.05 to 0.159, respectively. Conclusions: A decrease in the IL-10/IL-6 ratio seems to be related to a decrease in vitreous opacity. Measuring the IL-10/IL-6 ratio in the anterior chamber may be useful to evaluate the effect of treatment of vitreoretinal lymphoma.
Efficacy of Oral Sucrose in Infants of Methadone-Maintained Mothers
Authors: Marceau James R. , Murray Henry , Nanan Ralph K.H.
Published: July 2009

Background: One report indicated that taste-induced analgesia was sub-optimal in methadone-exposed (ME) infants. Objectives: The purpose of this work was to compare the effects of oral sucrose in infants born to methadone-maintained mothers with control infants. Methods: The aim was to compare the effects of an oral sucrose solution in infants scheduled to have a heel lance procedure for routine newborn screening. Infants received 0.05 ml (one drop) of a 24% sucrose solution by mouth 2 min before a heel lance procedure, then a further 0.05 ml of sucrose at the time of the heel lance; this was repeated every 1–2 min until 30 s after the completion of the procedure. The primary outcome measure was pain. We assessed pain using the Premature Infant Pain Profile (PIPP), which is a validated composite pain assessment tool. Results: PIPP scores were similar in both infant groups. Median PIPP scores of the ME infant group versus the control infant group were 2.0 (interquartile range (IQR) 0–7) versus 2.0 (IQR 0–9) at the time of the heel lance (p = 0.99) and 2.0 (IQR 0–4) versus 1.0 (IQR 0–4) 30 s after the completion of the heel lance procedure (p = 0.28). Conclusions: This study found no differences in the pain responses of ME infants and non-exposed infants when given sucrose during heel lance procedures.