bluuebunny/crossref_metadata_2025 huggingface dataset:
Hedging their bets: tobacco and gambling industries work against smoke-free policies
Authors: Mandel L L , Glantz S A
Published: August 2004

Objective:To describe and understand the relationship between the tobacco and gambling industries in connection to their collaborative efforts to prevent smoke-free casinos and gambling facilities and fight smoke-free policies generally.

Methods:Analysis of tobacco industry documents available online (accessed between February and December 2003).

Results:The tobacco industry has worked to convince the gambling industry to fight against smoke-free environments. Representatives of the gambling industry with ties to the tobacco industry oppose smoke-free workplaces by claiming that smoke-free environments hurt gambling revenue and by promoting ventilation as a solution to secondhand smoke. With help from the tobacco industry, the gambling industry has become a force at the American Society of Heating Refrigeration and Air Conditioning Engineers opposing smoke-free ventilation standards for the hospitality industry.

Conclusion:Tobacco industry strategies to mobilise the gambling industry to oppose smoke-free environments are consistent with past strategies to co-opt the hospitality industry and with strategies to influence policy from behind the scenes. Tobacco control advocates need to be aware of the connections between the tobacco and gambling industries in relation to smoke-free environments and work to expose them to the public and to policy makers.
Interspecific competition and tolerance to defoliation in four grassland species
Authors: del-Val Ek , Crawley Michael J
Published: August 2004

Herbivory and competition are known to influence plant performance. Recent investigations showed that tolerance is an important strategy for plant survival under herbivory, but few have examined its interaction with plant competition. We evaluated in a greenhouse experiment if plant tolerance to defoliation is related to species presence in a grazed habitat and how plant tolerance to herbivory changes in a competitive environment. Regrowth capacity of four grassland species, Trifolium repens L., Rumex acetosella L., Vicia sativa L. subsp. nigra (L.) Ehrh., and Senecio jacobaea L., was evaluated as the capacity to compensate for 75% of aboveground biomass removed. Target plants were also grown in competition with Festuca rubra L. subsp. rubra, and different clipping treatments were applied. Plant biomass (above- and below-ground) was measured after 5 months. Rumex acetosella, T. repens, and S. jacobaea were able to compensate fully when grown alone. In competition, only R. acetosella was still able to regrow. In no case did clipping the competitor improve target plant performance (i.e., no beneficial effect from competitor release). These results highlight the importance of considering plant competition when studying plant responses to herbivory.Key words: herbivory, regrowth, competitor release, biomass compensation.
Model analysis of the importance of reiteration for branch longevity inPseudotsuga menziesiicompared withAbies grandis
Authors: Kennedy Maureen C , Ford E David , Ishii Hiroaki
Published: August 2004

Reiteration is an important process in the maintenance of tree crowns and in plant longevity. We use a geometric simulation model of branch growth to explore differences in longevity between old-growth Pseudotsuga menziesii (Mirb.) Franco and Abies grandis (D. Don ex Lamb.) Lindl. branches. Reiteration is defined through rules that reflect apical dominance relationships, and these rules are used to define shoot cluster units (SCU) on P. menziesii branches. Reiteration through epicormic production dominates growth in simulated P. menziesii branches and is shown to be a major factor that differentiates growth between P. menziesii and A. grandis. Branch growth is shown to be highly sensitive to rules for bifurcation and capacity for reiteration. The rules employed in the model that define epicormic initiation and SCU independence reveal possible physiological mechanisms through which reiteration occurs in P. menziesii. A simple morphological rule fails to simulate branch growth adequately, whereas a physiological rule through epicormic initiation after release from inhibition of a lateral axis yields realistic simulated branches. Branch growth is best simulated through a combination of physiological controls and morphological rules.Key words: reiteration, old growth, architecture, branch modeling, longevity.
Dielectric functions and dispersion relations of ultra-relativistic plasmas with collisions
Authors: Carrington M E , Fugleberg T , Pickering D , Thoma M H
Published: August 2004

In the present paper, we calculate the dielectric functions of an ultra-relativistic plasma, such as an electronpositron or a quarkgluon plasma. We use classical transport theory and take into account collisions within the relaxation time approximation. From these dielectric functions we derive the dispersion relations of longitudinal and transverse plasma waves. PACS Nos.: 12.38.Mh, 52.25.Dg, 52.27.Ep, 52.35.Hr
Chebyshev finite-difference method for the effects of Hall and ion-slip currents on magneto-hydrodynamic flow with variable thermal conductivity
Authors: Elshehawey E F , Eldabe N T , Elbarbary E M , Elgazery N S
Published: August 2004

In this paper, the problem of heat transfer to the magneto-hydrodynamic flow of a micropolar, viscous, incompressible, and electrically conducting fluid from an isothermal stretching sheet with suction and blowing through a porous medium under the effects of Hall and ion-slip currents and variable thermal conductivity is studied numerically by using the Chebyshev finite-difference method. The governing fundamental equations on the assumption of a small magnetic Reynolds number are approximated by a system of nonlinear ordinary differential equations. Details of the velocities and temperature fields are presented for the various values of the parameters of the problem, e.g., the magnetic, Hall, ion-slip, porous, thermal conductivity, and surface mass transfer parameters. The numerical results indicate that the velocity and the angular velocity increase as the permeability parameter increases. Also, the temperature decreases as the permeability parameter increases but it increases as the thermal conductivity parameter increases. PACS No.:45.65.+a
A multiscale finite-element method for solving rough-surface elastic-contact problems
Authors: Yao Y , Schlesinger M , Drake G WF
Published: August 2004

A novel multiscale finite-element method to investigate the elastic contact of two-dimensional rough surfaces is presented. The aim of the method is to find the microscopic curve that describes the deformed shape of a solid with a smooth boundary surface in frictionless contact with a rigid rough surface. In addition, the real contact area is studied through the surface deformation. The contact traction on the contact surface and the maximum shear stress around the contact region are analyzed. This method is based on the variational inequality approach for solving the elastic frictionless contact problem. The strategy is to separate a small slice within the contact region and solve it as an independent system. Then the contact traction is obtained through iterations between the solution of the independent small slice and the solution of the total solid body. We observe a much higher pressure than the result of Hertz theory around the asperities. The main conclusions are (1)~the actual contact area and surface traction are dependent on the wavelength and amplitude of the surface roughness, (2) there is a much higher pressure around the asperities than predicted by Hertz theory, and (3) the location of maximum shear stress tends to be shifted toward the surface as compared with the case of smooth-surface contact. The method has the potential to be extended to solve three-dimensional rough contact problems.PACS Nos.: 03.40.D, 46.30.P, 62.20.P
An experimental investigation of the influence of an electrostatic potential on electron mass as predicted by Weber's force law
Authors: Junginger J E , Popovic Z D
Published: August 2004

Assis (J. Phys. Soc. Jpn.} 62, 1418 (1993.) showed that Weber's force law between moving charges leads to the conclusion that the inertial mass of an electron depends on the charges that surround it. The experimental confirmation of this effect was claimed by Mikhailov (Annal. Fond. Louis de Broglie, 24, 161 (1999).) who detected frequency changes of a glow discharge lamp oscillator as a function of the voltage applied to the shield surrounding the oscillator. We carefully repeated the experiment employing an optical rather than the electrical coupling, used by Mikhailov, to measure the oscillator frequency as a function of shield voltage. Our results did not show any frequency changes associated with the change in shield voltage that could be interpreted as a change in the electron mass induced by the surrounding charges. As this effect is an inescapable consequence of Weber's force law, our experiment strongly indicates that this force law is not valid.PACS No.: 41.20.q
UNIQUENESS OF EXTREMAL KÄHLER METRICS FOR AN INTEGRAL KÄHLER CLASS
Authors: MABUCHI TOSHIKI
Published: August 2004

For an integral Kähler class on a compact connected complex manifold, an extremal Kähler metric, if any, in the class is unique up to the action of Aut 0(M). This generalizes a recent result of Donaldson (see [4] for cases of metrics of constant scalar curvature) and that of Chen [3] for c1(M)≤0.
ASYMPTOTIC BEHAVIORS OF THE COLORED JONES POLYNOMIALS OF A TORUS KNOT
Authors: MURAKAMI HITOSHI
Published: August 2004

We study the asymptotic behaviors of the colored Jones polynomials of torus knots. Contrary to the works by R. Kashaev, O. Tirkkonen, Y. Yokota, and the author, they do not seem to give the volumes or the Chern–Simons invariants of the three-manifolds obtained by Dehn surgeries. On the other hand it is proved that in some cases the limits give the inverse of the Alexander polynomial.
ALMOST KÄHLER 4-MANIFOLDS, L2-SCALAR CURVATURE FUNCTIONAL AND SEIBERG–WITTEN EQUATIONS
Authors: ITOH MITSUHIRO
Published: August 2004

We show in this paper by applying the Seiberg–Witten theory developed by Taubes and LeBrun that a compact almost Kähler–Einstein 4-manifold of negative scalar curvature s is Kähler–Einstein if and only if the L2-norm satisfies ∫Ms2dv=32π2(2χ+3τ)(M). The Einstein condition can be weakened by the topological condition (2χ+3τ)(M)>0.
SELF-DOPING EFFECT OBSERVED ON HEAVY ION IRRADIATED Bi 2212 THIN FILMS
Authors: STIUFIUC R. , STIUFIUC G. , MACOCIAN E. , RAFFY H. , ILONCA G.
Published: August 2004

In our studies we observed a self-doping effect in Bi 2212 epitaxial thin films, totally covered by a protective golden layer, after the irradiation of these films with heavy ions. The irradiation with heavy ions was made in order to create columnar defects in the samples. We studied Bi 2212 thin films having various oxygen contents before irradiation and we observed for all of them an increase of the oxygen content in the films due to this self-doping effect caused by irradiation.
TRANSIENT BROWNIAN MOTION IN RESPONSE TO A SUDDEN CHANGE OF TEMPERATURE
Authors: CHEN L. Y.
Published: August 2004

A path integral formulation is developed for the transient Brownian motion in response to a sudden change in temperature. Formulae are derived for the time-dependent probability distribution function and for the transient current, employing the negative friction Langevin equation. Numerical implementation of the theory for a double-well system gives a clear illustration of the transient of the transient behaviors of the system.
SYNTHESIS, MAGNETIC AND TRANSPORT PROPERTIES OF Ru1-xSbxSr2GdCu2O8 COMPOUNDS
Authors: ILONCA G. , PATAPIS S. , MACOCIAN E. , BEIUSAN F. , JURCUT T. , STIUFIUC G. , STIUFIUC R.
Published: August 2004

Polycrystalline samples with a nominal composition Ru 1-x Sb x Sr 2 GdCu 2 O 8-d were prepared by a solid state reaction technique. A mixture of RuO 2, Sb 2 O 3, Gd 2 O 3, SrCO 3 and CuO was used to obtain the samples. We performed X-ray diffraction analyses, DC susceptibility and transport measurements and the studies showed that the samples were almost pure Ru -1212 phase. We also observed that Sb doping reduce the conductivity of the system and the transition temperature decreases with increasing Sb content. This may be due to a distortion of RuO 6 octahedral which is responsible for the increase of holes localization.
PROBABILISTIC CELLULAR AUTOMATA DESCRIBING A BIOLOGICAL TWO-SPECIES SYSTEM
Authors: DE CARVALHO KELLY C. , TOMÉ TÂNIA
Published: August 2004

We consider two probabilistic cellular automata to analyze the stochastic dynamics of a biological two-species system. We focus our attention on the characterization of the dynamic patterns exhibited by both models. Performing Monte Carlo simulations, we observe a time oscillating behavior that occurs at a local level.
FUNCTIONS ON GROUPS AND COMPUTATIONAL COMPLEXITY
Authors: BIRGET JEAN-CAMILLE
Published: August 2004

We give some connections between various functions defined on finitely presented groups (isoperimetric, isodiametric, Todd–Coxeter radius, filling length functions, etc.), and we study the relation between those functions and the computational complexity of the word problem (deterministic time, nondeterministic time, symmetric space). We show that the isoperimetric function can always be linearly decreased (unless it is the identity map). We present a new proof of the Double Exponential Inequality, based on context-free languages.
A SPELLING THEOREM FOR TORSION-FREE ONE-RELATOR PRESENTATIONS
Authors: JUHÁSZ ARYE
Published: August 2004

One-relator presentations with torsion are characterized by relators which are proper powers of cyclically reduced words. Such groups have a spelling theorem which provides among other things a quick solution of the word problem. In this paper we consider other classes of one-relator presentations (which are necessarily torsion-free) with a similar spelling theorem.
ON GROUPS WHICH ARE SYNTACTIC MONOIDS OF DETERMINISTIC CONTEXT-FREE LANGUAGES
Authors: RÖVER CLAAS E.
Published: August 2004

The author shows that the class of groups which are syntactic monoids of deterministic context-free languages is closed under restricted standard wreath products with virtually free top groups. This provides an answer to a question of T. Herbst.
EXOGENOUS REINFECTION AND RESURGENCE OF TUBERCULOSIS: A THEORETICAL FRAMEWORK
Authors: MOGHADAS S. M. , ALEXANDER M. E.
Published: August 2004

The importance of exogenous reinfection versus endogenous reactivation for the resurgence of tuberculosis (TB) has been a matter of ongoing debate. Previous mathematical models of TB give conflicting results on the possibility of multiple stable equilibria in the presence of reinfection, and hence the failure to control the disease even when the basic reproductive number is less than unity. The present study reconsiders the effect of exogenous reinfection, by extending previous studies to incorporate a generalized rate of reinfection as a function of the number of actively infected individuals. A mathematical model is developed to include all possible routes to the development of active TB (progressive primary infection, endogenous reactivation, and exogenous reinfection). The model is qualitatively analyzed to show the existence of multiple equilibria under realistic assumptions and plausible range of parameter values. Two examples, of unbounded and saturated incidence rates of reinfection, are given, and simulation results using estimated parameter values are presented. The results reflect exogenous reinfection as a major cause of TB emergence, especially in high prevalence areas, with important public health implications for controlling its spread.
HOPF BIFURCATION AND PERMANENCE ANALYSIS OF AN S-I EPIDEMIC MODEL WITH DELAY
Authors: DAS PRASENJIT , MUKHERJEE DEBASIS
Published: August 2004

A Susceptible-Infective (S-I) model is considered in this paper with time delay. The death rate is assumed to be density dependent for this model. Conditions are derived under which there can be no change in stability. Using the discrete time delay as a bifurcation parameter, we show that the model undergoes a Hopf bifurcation. The permanence conditions of the system have also been derived. Results are verified by computer simulation.
ANALYSIS OF MORPHOLOGICAL GROUPINGS USING ANOPA, A PATTERN RECOGNITION AND MULTIVARIATE STATISTICAL METHOD: A CASE STUDY INVOLVING CENTRARCHID FISHES
Authors: CAVANAUGH DAVID P. , STERNBERG RICHARD V.
Published: August 2004

Morphological relationships within and among taxonomic groups can be very complicated, with anatomical data often supporting two or more incongruent groupings. One possibility is that incongruent character states are taxonomically informative, although in an N-dimensional taxic space. To test the above, morphological relationships of centrarchid fish species were examined using a new pattern recognition, multivariate correlation, and multivariate statistical analysis method (ANOPA). The objective of ANOPA is to identify N-dimensional pattern space correlations among character states, relations that cannot be detected with standard phenetic or phylogenetic approaches. ANOPA provides a solution to an inherent weakness in statistical analysis which occurs in the face of set classification ambiguity, where there is no a priori reason to assign a membership or class identification within multivariate statistical groups. This approach revealed the percoid fish family Centrarchidae to be a statistically significant, cohesive group with complicated internal relationships. Centrarchid taxa are resolved into three major generic aggregates by two and three-dimensional ANOPA, and discrete subgroups were also detected. The complex interrelationships within the Centrarchidae cannot be readily collapsed to a bifurcating tree-structure, explaining the multitude of conflicting phylogenetic hypotheses that have been presented. This is the first robust study of anatomical disparity in teleostean fishes. Applications of ANOPA to the study of morphological gaps, complex taxonomic patterns, and anatomical disparity are discussed.
NUMERICAL INVESTIGATIONS OF A CENTRIFUGAL BLOOD PUMP
Authors: CHAN W. K. , WONG Y. W. , DING Y.
Published: August 2004

This paper presents computational fluid dynamics (CFD) studies of a centrifugal blood pump. 3-D models of five different blade geometries are investigated numerically using CFX-TASCflow. The impellers were designed using an inverse design technique where the swirl distributions were prescribed. The results showed the flow in the impeller passages is highly dependent on the impeller blade profiles. The flow in the radial blade impeller is unsatisfactory as flow separates at the leading edge of the suction side. Flow is confined mainly to the pressure side. Design 2, with an inlet angle of 6.7° and outlet angle of 30°, offers the greatest potential as only a small region of flow reversal is detected. Further optimization is necessary to completely eliminate regions of flow reversals. The highest scalar shear stress in both designs is 240 Pa and 120 Pa respectively. In addition, this paper demonstrates that the use of inverse design can help the designer to better design and analyze the flow field in centrifugal blood pumps.
DETERMINATION OF TRANSFER FUNCTIONS OF MCP-200 ALLOY USING 6 MV PHOTON BEAM FOR BEAM INTENSITY MODULATION
Authors: MAQBOOL MUHAMMAD
Published: August 2004

Transfer functions of MCP-200 alloy were determined for beam intensity modulation. 6 MV Photon beam, obtained from linear accelerator, is attenuated by blocks of MCP-200 alloy with different thicknesses placed at a distance of one meter from the source. The attenuated beam was allowed to fall on photographic film and optical densities were measured. Films were scanned and profiles were obtained for different thicknesses of the alloy and in the absence of any attenuator. Transfer functions were obtained theoretically as well as analytically by fitting the experimental results into theoretical data. The whole work was completed using optimum dose units and found to be 30 cGy.
WAVELET TRANSFORM SELECTION FOR THE COMPRESSION OF THE ELECTROCARDIOGRAM (ECG) SIGNAL
Authors: MOHAMED BENAISSA , ABDELGHANI DJEBBARI , FETHI BEREKSI REGUIG
Published: August 2004

In this paper, we are interested in the development of a compression method using wavelets for the Electrocardiogram (ECG) signal. The choice of the analyzing wavelet is of great importance for an optimal compression. Results obtained by the proposed algorithm consist of weak Compression Ratios (CR) for an acceptable Percentage RMS Difference (PRD) of the signal. Tests and measurements achieved by the application of our compression algorithm on the entire arrhythmias database MIT-BIH allow us to select, for a better compression, the adequate wavelets having from three to seven zero moments.
CLASSIFICATION OF VENTRICULAR ECTOPIC BEATS (VEB'S) USING NEURAL NETWORKS
Authors: CHIKH M. A. , BEREKSI–REGUIG F.
Published: August 2004

The most widely used signal in clinical practice is the electrocardiogram (ECG). ECG conveys information regarding the electrical function of the heart, by altering the shape of its constituent waves, namely the P, QRS, and T waves. Thus, the required tasks of ECG processing are the reliable recognition of these waves, and the accurate measurement of clinically important parameters measured from the temporal distribution of the ECG constituent waves. The purpose of this paper is the classification of ventricular ectopic beats (VEB's). This research includes noise handling, feature extraction, and neural classification, all integrated in a three-stage procedure. Thirty features extracted from the morphology of the QRS segment, are reduced to seven coefficients using principal component analysis (PCA) and two coefficients using linear predictive coding (LPC) technique in addition to two other temporal parameters were used separately as the input of two neural network classifiers. The neural classifiers were tested on the MIT-BIH database and high scores were obtained for both sensitivity and specificity (84.88% and 91.92% respectively using ACP technique, and 76.17% and 88.95% using LPC method). This study confirms the power of artificial neural networks in the classification of normal and abnormal VEB beats. Clinical use of this method, however, still requires further investigation.
THE EFFECTIVENESS OF INNOVATION: A KNOWLEDGE MANAGEMENT APPROACH
Authors: ABOU-ZEID EL-SAYED , CHENG QIANZHEN
Published: August 2004

With the emergence of knowledge management (KM) as a new discipline for studying what needs to be done in order to get the most out of organizational knowledge resources, linking knowledge management and innovation becomes a necessity. Nevertheless, there are few studies that address the relationship between KM and innovation. While the thing- and process-oriented approaches adopted in these studies are helpful in understanding the relationship between knowledge management concepts and innovation concepts, they have failed to account for the impact of this relationship on the effectiveness of the innovation process. In order to study this impact, cognitive fit theory is used to develop a model that describes how the compatibility between knowledge manipulating activities and the type of knowledge associated with innovation will affect the success of the innovation process.
An in vitro model based on cell monolayers grown on the underside of large- pore filters in bicameral chambers for studying thyrocyte-lymphocyte interactions
Authors: Estienne Valérie , Brisbarre Nadège , Blanchin Stéphanie , Durand-Gorde Josée-Martine , Carayon Pierre , Ruf Jean
Published: August 2004

In the processes underlying thyroid autoimmunity, thyrocytes probably act as antigen-presenting cells exposing T-cell epitopes to intrathyroid lymphocytes. To study the interactions between lymphocytes and thyrocytes, which are arranged in a tight, polarized monolayer, we developed a new in vitro model based on human thyrocytes grown on the underside of a filter placed in a bicameral chamber. Thyrocytes from Graves' disease glands were plated onto the upper face of a 8-μm-pore polyethylene terephthalate culture insert filter placed in the inverted position and grown for 24 h before the insert was returned to the normal position for a week in the cell culture plate wells. Thyrocytes grown in the presence of thyroid stimulating hormone, forming a homogeneous monolayer on the underside of the filter, reached confluence after 8 days in vitro. The cells developed a transepithelial electrical resistance >1,000 Ω·cm2, and the ZO-1 tight junction protein showed a junctional pattern of distribution. Thyrocytes showed a polarized pattern of thyroperoxidase and thyroid stimulating hormone receptor expression in the apical and basolateral positions, respectively. They were also found to aberrantly express DR class II human leukocyte antigen and an Fc immunoglobulin receptor (FcγRIIB2) in the basolateral and apical positions, respectively. Autologous intrathyroidal T lymphocytes cocultured for 24 h across the filter with the thyrocyte monolayer proliferated and remained in the upper chamber without any leakage occurring through the epithelial barrier, which makes this model particularly suitable for studying the cell-cell interactions involved in antigen processing.
l-Glutamine ameliorates acetaldehyde-induced increase in paracellular permeability in Caco-2 cell monolayer
Authors: Seth A. , Basuroy S. , Sheth P. , Rao R. K.
Published: August 2004

Role of l-glutamine in the protection of intestinal epithelium from acetaldehyde-induced disruption of barrier function was evaluated in Caco-2 cell monolayer. l-Glutamine reduced the acetaldehyde-induced decrease in transepithelilal electrical resistance and increase in permeability to inulin and lipopolysaccharide in a time- and dose-dependent manner; d-glutamine, l-aspargine, l-arginine, l-lysine, or l-alanine produced no significant protection. The glutaminase inhibitor 6-diazo-5-oxo-l-norleucine failed to affect the l-glutamine-mediated protection of barrier function. l-Glutamine reduced the acetaldehyde-induced redistribution of occludin, zonula occludens-1 (ZO-1), E-cadherin, and β-catenin from the intercellular junctions. Acetaldehyde dissociates occludin, ZO-1, E-cadherin, and β-catenin from the actin cytoskeleton, and this effect was reduced by l-glutamine. l-Glutamine induced a rapid increase in the tyrosine phosphorylation of EGF receptor, and the protective effect of l-glutamine was prevented by AG1478, the EGF-receptor tyrosine kinase inhibitor. These results indicate that l-glutamine prevents acetaldehyde-induced disruption of the tight junction and increase in the paracellular permeability in Caco-2 cell monolayer by an EGF receptor-dependent mechanism.
Insulin sensitivity is mediated by the activation of the ACh/NO/cGMP pathway in rat liver
Authors: Guarino Maria P. , Correia Nina C. , Lautt W. Wayne , Macedo M. Paula
Published: August 2004

The hepatic parasympathetic nerves and hepatic nitric oxide synthase (NOS) are involved in the secretion of a hepatic insulin sensitizing substance (HISS), which mediates peripheral insulin sensitivity. We tested whether binding of ACh to hepatic muscarinic receptors is an upstream event to the synthesis of nitric oxide (NO), which, along with the activation of hepatic guanylate cyclase (GC), permits HISS release. Male Wistar rats (8–9 wk) were anesthetized with pentobarbital sodium (65 mg/kg). Insulin sensitivity was assessed using a euglycemic clamp [the rapid insulin sensitivity test (RIST)]. HISS inhibition was induced by antagonism of muscarinic receptors (atropine, 3 mg/kg iv) or by blockade of NOS [ NG-nitro-l-arginine methyl ester (l-NAME), 1 mg/kg intraportally (ipv)]. After the blockade, HISS action was tentatively restored using a NO donor [3-morpholynosydnonimine (SIN-1), 5–10 mg/kg ipv] or ACh (2.5–5 μg·kg−1·min−1 ipv). SIN-1 (10 mg/kg) reversed the inhibition caused by atropine (RIST postatropine 137.7 ± 8.3 mg glucose/kg; reversed to 288.3 ± 15.5 mg glucose/kg, n = 6) and by l-NAME (RIST post-l-NAME 152.2 ± 21.3 mg glucose/kg; reversed to 321.7 ± 44.7 mg glucose/kg, n = 5). ACh did not reverse HISS inhibition induced by l-NAME. The role of GC in HISS release was assessed using 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 5 nmol/kg ipv), a GC inhibitor that decreased HISS action (control RIST 237.6 ± 18.6 mg glucose/kg; RIST post-ODQ 111.7 ± 6.2 mg glucose/kg, n = 5). We propose that hepatic parasympathetic nerves release ACh, leading to hepatic NO synthesis, which activates GC, triggering HISS action.
Recent Advances in Alcoholic Liver Disease IV. Dysregulated cytokine metabolism in alcoholic liver disease
Authors: McClain Craig J. , Song Zhenyuan , Barve Shirish S. , Hill Daniell B. , Deaciuc Ion
Published: August 2004

Alcoholic liver disease (ALD) remains a leading cause of death from liver disease in the United States for which there is no FDA-approved therapy. Abnormal cytokine metabolism is a major feature of ALD. Elevated serum concentration levels of TNF-α and TNF-α-inducible cytokines/chemokines, such as IL-6, -8, and -18, have been reported in patients with alcoholic hepatitis and/or cirrhosis, and levels correlated with markers of the acute phase response, liver function, and clinical outcome. Studies in animal models support an etiologic role for cytokines in the liver injury of ALD. Cytokines, such as transforming growth factor-β, play a critical role in the fibrosis of ALD. Multiple new strategies are under investigation to modulate cytokine metabolism as a form of therapy for ALD.
α2-Adrenergic regulation of NO production alters postoperative intestinal smooth muscle dysfunction in rodents
Authors: Kreiss Christianna , Toegel Sandra , Bauer Anthony J.
Published: August 2004

α2-Adrenergic receptor activation plays an important role in the development of postoperative ileus. α2-Adrenergic receptors also regulate nitric oxide (NO) production by the mononuclear phagocyte system. We have previously shown that intestinal manipulation leads to a significant increase in NO production by infiltrating monocytes within the intestinal muscularis. The purpose of this study was to investigate whether α2-adrenergic blockade with yohimbine would alter postsurgical intestinal smooth muscle dysfunction and NO production by infiltrating monocytes and macrophages within the intestinal muscularis. Rats underwent small bowel intestinal manipulation with or without yohimbine. In vivo gastrointestinal transit and in vitro jejunal circular muscle contractility was measured 24 h postoperatively. RT-PCR was used to detect inducible NO synthase (iNOS) expression. NO levels in tissue culture supernatants were measured. Immunohistochemistry was used to localize α2-adrenergic receptor expression in the intestinal muscularis. Yohimbine significantly decreased manipulation-induced delay in gastrointestinal transit and reversed the postoperative decrease in intestinal muscle contractility. Intestinal manipulation resulted in significant iNOS mRNA induction in the intestinal muscularis, which was markedly attenuated after yohimbine treatment. Yohimbine also significantly decreased the postoperative increase in NO released into intestinal muscularis tissue culture supernatant. Immunohistochemistry identified α2-adrenergic receptors on monocytes recruited postoperatively into the intestinal muscularis. This study demonstrates that α2-adrenergic receptor stimulation of the inflamed postoperative intestinal muscularis plays a significant role in aggravating postoperative ileus through an enhanced induction of iNOS mRNA and increased release of NO from manipulated intestinal muscularis.
Endogenous production of ghrelin and beneficial effects of its exogenous administration in monocrotaline-induced pulmonary hypertension
Authors: Henriques-Coelho Tiago , Correia-Pinto Jorge , Roncon-Albuquerque Roberto , Baptista Maria J. , Lourenço André P. , Oliveira Sílvia Marta , Brandão-Nogueira Ana , Teles Antónia , Fortunato José M. , Leite-Moreira Adelino F.
Published: August 2004

We investigated the endogenous production of ghrelin as well as cardiac and pulmonary vascular effects of its administration in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). Adult Wistar rats randomly received a subcutaneous injection of MCT (60 mg/kg) or an equal volume of vehicle. One week later, animals were randomly assigned to receive a subcutaneous injection of ghrelin (100 μg/kg bid for 2 wk) or saline. Four groups were analyzed: normal rats treated with ghrelin ( n = 7), normal rats injected with saline ( n = 7), MCT rats treated with ghrelin ( n = 9), and MCT rats injected with saline ( n = 9). At 22–25 days, right (RV) and left ventricular (LV) pressures were measured, heart and lungs were weighted, and samples were collected for histological and molecular analysis. Endogenous production of ghrelin was almost abolished in normal rats treated with ghrelin. In MCT-treated animals, pulmonary expression of ghrelin was preserved, and RV myocardial expression was increased more than 20 times. In these animals, exogenous administration of ghrelin attenuated PH, RV hypertrophy, wall thickening of peripheral pulmonary arteries, and RV diastolic disturbances and ameliorated LV dysfunction, without affecting its endogenous production. In conclusion, decreased tissular expression of ghrelin in healthy animals but not in PH animals suggests a negative feedback in the former that is lost in the latter. A selective increase of ghrelin mRNA levels in the RV of animals with PH might indicate distinct regulation of its cardiac expression. Finally, ghrelin administration attenuated MCT-induced PH, pulmonary vascular remodeling, and RV hypertrophy, indicating that it may modulate PH.
Integrative control of the skeletal muscle microcirculation in the maintenance of arterial pressure during exercise
Authors: Delp Michael D. , O'Leary Donal S.
Published: August 2004

Skeletal muscle blood flow and vascular conductance are influenced by numerous factors that can be divided into two general categories: central cardiovascular control mechanisms and local vascular control mechanisms. Central cardiovascular control mechanisms are thought to be designed primarily for the maintenance of arterial pressure and central cardiovascular homeostasis, whereas local vascular control mechanisms are thought to be designed primarily for the maintenance of muscle homeostasis. To support the high metabolic rates that can be generated during muscle contraction, skeletal muscle has a tremendous capacity to vasodilate and increase oxygen and nutrient delivery. During whole body dynamic exercise at maximal oxygen consumption (V̇o2 max), the skeletal muscle receives 85–90% of cardiac output. Yet despite receiving such a large fraction of cardiac output during high-intensity exercise, a vasodilator reserve remains with the potential to produce further elevations in skeletal muscle vascular conductance and blood flow. However, because maximal cardiac output is reached during exercise at V̇o2 max, further elevations in muscle vascular conductance would produce a fall in arterial pressure. Therefore, limits on muscle perfusion must be imposed during whole body exercise to prevent such drops in pressure. Effective arterial pressure control in response to a potentially hypotensive challenge during high-intensity exercise occurs primarily through reflex-mediated increases in sympathetic nerve activity, which are capable of modulating vasomotor tone of the skeletal muscle resistance vasculature. Thus skeletal muscle vascular conductance and perfusion are primarily mediated by local factors at rest and during exercise, but other centrally mediated control systems are superimposed on the dominant local control mechanisms to provide an integrated regulation of both arterial pressure and skeletal muscle vascular conductance and perfusion during whole body dynamic exercise.
Response Characteristics of Spinal Cord Dorsal Horn Neurons in Chronic Allodynic Rats After Spinal Cord Injury
Authors: Hao Jing-Xia , Kupers Ron C. , Xu Xiao-Jun
Published: August 2004

The physiological mechanisms of chronic pain in patients with spinal cord injury (SCI) are poorly understood. In the present study, we explored response characteristics of dorsal horn neurons of spinally injured rats exhibiting chronic pain (pain-like response to innocuous mechanical and cold stimulation). Several abnormalities were found in the distribution and response characteristics of dorsal horn neurons in chronic allodynic rats. First, 17% of the recorded neurons (vs. 0% in control animals) had no receptive field. Most of these units were located at or close to the lesioned spinal segment, and they discharged spontaneously at high frequencies. Allodynic rats also showed a significant decrease in the proportion of low-threshold (LT) neurons and an increase in the proportion of wide dynamic range (WDR) neurons. The rate of spontaneous activity of high-threshold (HT) neurons was significantly higher in allodynic compared with control rats. Moreover, HT neurons in allodynic animals showed increased neuronal responses to mechanical stimulation. WDR neurons responded with higher discharge rates to innocuous von Frey hair stimulation in allodynic compared with control rats. The percentage of WDR and HT neurons showing afterdischarges to noxious pinch was also significantly increased in the allodynic rats. The proportion of WDR and HT neurons responding to innocuous cold stimulation respectively increased from 53 and 25% in control rats to 91 and 75% in allodynic animals. These results suggest that the chronic pain-like behaviors in spinally injured rats may be generated and maintained by abnormalities in dorsal horn neurons.
Odorant Responses of Dual Polarity Are Mediated by cAMP in Mouse Olfactory Sensory Neurons
Authors: Delay Rona , Restrepo Diego
Published: August 2004

Some olfactory sensory neurons (OSNs) respond to odors with hyperpolarization. Although transduction for excitatory responses is mediated by opening of a cyclic nucleotide-gated (CNG) channel, there is controversy on the mechanism underlying inhibitory responses. We find that mouse OSNs respond to odorants by either depolarizing or hyperpolarizing responses in loose-patch measurements. In the perforated-patch configuration, OSNs not only responded with a current consistent with CNG channel-mediated excitation but also displayed enhancement of outward currents, consistent with inhibitory responses. Increasing cAMP levels pharmacologically elicited excitatory or inhibitory responses in different OSNs. In addition, OSNs from mice defective for the CNGA2 subunit of the CNG channel displayed neither excitatory nor inhibitory responses. Thus CNG channels mediate inhibitory olfactory responses.
Repeated Cocaine Administration Suppresses HVA-Ca2+Potentials and Enhances Activity of K+Channels in Rat Nucleus Accumbens Neurons
Authors: Hu Xiu-Ti , Basu Somnath , White Francis J.
Published: August 2004

The nucleus accumbens (NAc) is an important forebrain area involved in sensitization, withdrawal effects, and self-administration of cocaine. However, little is known about cocaine-induced alterations in the neuronal excitability and whole cell neuroplasticity in this region that may affect behaviors. Our recent investigations have demonstrated that repeated cocaine administration decreases voltage-sensitive sodium and calcium currents (VSSCs and VSCCs, respectively) in freshly dissociated NAc neurons of rats. In this study, current-clamp recordings were performed in slice preparations to determine the effects of chronic cocaine on evoked Ca2+potentials and voltage-sensitive K+currents in NAc neurons. Repeated cocaine administration with 3–4 days of withdrawal caused significant alterations in Ca2+potentials, including suppression of Ca2+-mediated spikes, increase in the intracellular injected current intensity required for generation of Ca2+potentials (rheobase), reduced duration of Ca2+plateau potentials, and abolishment of secondary Ca2+potentials associated with the primary Ca2+plateau potential. Application of nickel (Ni2+), which blocks low-voltage activated T-type Ca2+channels, had no impact on evoked Ca2+plateau potentials in NAc neurons, indicating that these Ca2+potentials are high-voltage activated (HVA). In addition, repeated cocaine pretreatment also hyperpolarized the resting membrane potential, increased the amplitude of afterhyperpolarization in Ca2+spikes, and enhanced the outward rectification observed during membrane depolarization. These findings indicate that repeated cocaine administration not only suppressed HVA-Ca2+potentials but also significantly enhanced the activity of various K+channels in NAc neurons. They also demonstrate an integrative role of whole cell neuroplasticity during cocaine withdrawal, by which the subthreshold membrane excitability of NAc neurons is significantly decreased.
Primate Insular/Opercular Taste Cortex: Neuronal Representations of the Viscosity, Fat Texture, Grittiness, Temperature, and Taste of Foods
Authors: Verhagen Justus V. , Kadohisa Mikiko , Rolls Edmund T.
Published: August 2004

It is shown that the primate primary taste cortex represents not only taste but also information about many nontaste properties of oral stimuli. Of 1,122 macaque anterior insular/frontal opercular neurons recorded, 62 (5.5%) responded to oral stimuli. Of the orally responsive neurons, some (53%) represented the viscosity, tested using carboxymethyl-cellulose in the range 1–10,000 cP. Other neurons (8%) responded to fat in the mouth by encoding its texture (as shown similar responses to nonfat oils), and 8% responded to gritty texture. Some neurons (35%) responded to the temperature of the liquid in the mouth. Some neurons responded to capsaicin, and others to fatty acids. Some neurons (56%) had taste responses. Some (50%) of these neurons were unimodal, responding to one of these types of stimulus, and the majority combined responsiveness to these types of stimulus, with 23% responding for example to both taste and temperature. Some neurons respond to taste, texture, and temperature unimodally, but others combine these inputs. None of these orally responsive neurons responded to odor or to the sight of food. These results provide fundamental evidence about the information channels used to represent the taste, texture, and temperature of food in the first cortical area involved in taste in the primate brain. The results are relevant to understanding the physiological and pathophysiological processes related to how the properties of oral stimuli are represented in the brain and thus to the control of food intake and food selection.
Primate Retinal Signaling Pathways: Suppressingon-Pathway Activity in Monkey With Glutamate Analogues Mimics Human CSNB1-NYXGenetic Night Blindness
Authors: Khan Naheed W. , Kondo Mineo , Hiriyanna Kelaginamane T. , Jamison Jeff A. , Bush Ronald A. , Sieving Paul A.
Published: August 2004

Retinal on-pathway dysfunction is implicated in human complete-type congenital stationary night blindness (CSNB1), a Mendelian genetic condition that results from mutations in the NYX gene encoding the protein nyctalopin. We probed cone pathway dysfunction in four human genotyped CSNB1 affected males by electroretinogram (ERG) recordings elicited with photopic sinusoidal and rapid-on/off-ramp flicker stimuli that are reputed to elicit on/off-pathway activity selectively. Results were analyzed in relation to ERG abnormalities created in anesthetized non-human primates by intravitreal application of glutamate analogues that selectively suppress retinal on- or off-pathway bipolar cell activity. 2-amino-4-phosphonobutyric acid (APB), which selectively blocks light responses of on-pathway depolarizing bipolar cells, fully recreated the essential ERG abnormalities found for human CSNB1 under the condition that the off-pathway remained active. Both CSNB1- NYX humans and APB-treated monkey retina lacked the normal amplitude dip and the phase deflection that occurs in the fundamental component near 12 Hz for sinusoidal flicker stimuli. The off-pathway suppressing agent, cis-2,3-piperidine-dicarboxylic acid (PDA), gave results in monkey quite discordant to CSNB1 human for sinusoidal stimulation. The results implicated a specific on-pathway signaling deficiency in CSNB1- NYX males with no evidence of off-pathway involvement. Likewise, rapid-on/off ramping stimuli also indicated that the functional deficit was localized to the on pathway. Analysis of non-human primate retinal responses after drug application demonstrated a complexity to on/off-pathway contributions to ramping on/off ERG responses not previously anticipated. These results support the hypothesis that nyctalopin acts principally or exclusively within the on pathway at the level of depolarizing bipolar cells, and thus human CSNB1- NYX subjects provide an opportunity to probe the primate visual system for consequences of on-pathway deficits.
Voltage-Controlled Plasticity at GluR2-Deficient Synapses Onto Hippocampal Interneurons
Authors: Laezza Fernanda , Dingledine Raymond
Published: August 2004

High-frequency stimulation of pyramidal cell inputs to developing (P9-12) hippocampal stratum radiatum interneurons expressing GluR2-lacking, Ca2+-permeable AMPA receptors produces long-term depression of synaptic transmission, if N-methyl-d-aspartate (NMDA) receptors are blocked. Here we show that these same synapses display a remarkably versatile signal integration if postsynaptic NMDA receptors are activated. At synapses expressing GluR2-deficient AMPA receptors, tetanic stimulation that activates NMDA receptors triggered long-term potentiation or depression (LTP or LTD) depending on membrane potential. LTP was elicited at most synapses when the interneuron was held at –30 mV during the stimulus train but was typically prevented by postsynaptic hyperpolarization to –70 mV, by strong depolarization to 0 mV, by d-2-amino-5-phosphonovaleric acid, or by postsynaptic injection of the Ca2+ chelator bis-( o-aminophenoxy)- N,N,N′,N′-tetraacetic acid. At synapses with predominantly GluR2-containing AMPA receptors, repetitive stimulation did not change synaptic strength regardless of whether NMDA receptors were activated. The interactions among GluR2 expression, NMDA receptor expression, and membrane potential thus confer on hippocampal interneurons a distinctive means for differential decoding of high-frequency inputs, resulting in enhanced or depressed transmission depending on the functional state of the interneuron.