bluuebunny/crossref_metadata_2025 huggingface dataset:
DIRECT-DRIVE MOTOR SYSTEM WITH PARTICLE-TYPE ER FLUID DAMPER
Authors: KOYANAGI KEN'ICHI , FURUSHO JUNJI
Published: June 2005

In most of robotic systems in industrial applications, vibratory problems occur at high-speed motion, because of elasticity of drive systems like reduction gear units and mechanical structures. Also friction and backlash in the drive systems cause serious problems. On the other hand, since direct-drive (DD) motor systems do not use reduction gears, those are effective for high-speed and high-precision control. In DD motor systems, however, low damping ratio, or large time delays of computers and amplifiers causes another type of problem at precise positioning phase. In this study, a particle type ER fluid damper was introduced to a DD motor system to compensate damping ratio mechanically. Because controlling viscosity of ER damper according to status of motion did not disturb advantage of the DD system that can move fast, the performance of the DD system was improved. The effectiveness of the proposed system was confirmed experimentally. The method of our study can contribute to expansion of usability of ER fluid dampers on industrial applications not limited to DD systems.
PERFORMANCE OF PIN ELECTRODE ER VALVES
Authors: GEORGIADES G. , OYADIJI S. O.
Published: June 2005

This work concentrates on the development of an uncommon type of electrodes to be used in electrorheological devices. Rather than using electrodes with constant gap, pin electrodes are used, in order to achieve variation in the gap. The device described has pins running across the direction of the flow. The ER fluid moves through rows and columns of pin electrodes of different polarities. One of the main problems would be the development of the head pressure drop as the number of rows of pins increases. The work presents different configurations that could be constructed using pin electrodes. One of the configurations is developed and tested as to the pressure gradients that could be achieved when different magnitudes of electric potentials are applied. The results are compared to the ones obtained when two of the constructed modules are aligned one after the other for the tests.
CONTROL PERFORMANCE OF ER ENGINE MOUNT SUBJECTED TO TEMPERATURE VARIATIONS
Authors: SONG H. J. , CHOI S. B. , KIM K. S.
Published: June 2005

A key function of engine mount of vehicle systems is to support engine mass and isolate noise and vibration from engine disturbance forces. One of attractive candidates to achieve this goal is to utilize a semi-active ER engine mount. By applying this, we can effectively control damping force and hence the noise and vibration by just controlling the intensity of electric field. However, control performance of the engine mount may be very sensitive to temperature variation during engine operation. In this work, we investigate dynamic and control performances of ER engine mount with respect to the temperature variation. In order to undertake this, a flow-mode type of ER engine mount is designed and manufactured. Displacement transmissibility is experimentally evaluated for 1 degree of freedom. The ER engine mount is then incorporated with full-vehicle model in order to investigate vibration control performance. After formulating the governing equation of motion, a semi-active controller is designed. The controller is implemented through a hardware-in-the-loop simulation (HILS), and control responses such as acceleration level at various engine speeds are evaluated in the frequency and time domains.
POLISHING USING ER SLURRY ON ONE-SIDED PATTERNED ELECTRODES
Authors: KIKUCHI TAKEHITO , FUJIWARA JUNSUKE , FURUSHO JUNJI , INOUE AKIO
Published: June 2005

ER slurry, which is composed of an ER fluid and abrasive grains, is available for efficient polishing or finishing. In this study, we propose a final process with the ER slurry and one-sided patterned electrodes. Characteristics of the ER slurry were investigated. And, ER polishing, which is a polishing using the ER slurry, was carried out. Results showed that the impression of the electric field can accelerate the polishing.
SLIDING MODE CONTROL OF ER SEAT SUSPENSION CONSIDERING HUMAN VIBRATION MODEL
Authors: HAN Y. M. , JUNG J. Y. , CHOI S. B. , WERELEY N. M.
Published: June 2005

This paper presents robust control performances of a semi-active electro-rheological (ER) seat suspension incorporating vibration model of human-body. A cylindrical type of ER seat damper is manufactured for a commercial vehicle seat suspension system and its field-dependent damping force is experimentally evaluated. A human-body model is then derived and integrated with the governing equations of the ER seat suspension system. The integrated seat-driver model featured by a high order degree-of-freedom (DOF) is reduced through a balanced model reduction to design robust controller. By imposing semi-active actuating conditions, a sliding mode controller which is very robust to external disturbances and parameter uncertainties is synthesized and experimentally realized with the state observer. In the experimental configuration, a driver directly sits on the controlled seat. Control results for ride quality considering response of each human body segment are evaluated in both time and frequency domains. In addition, a comparison of the proposed semi-active ER seat suspension to a conventional passive seat suspension system is undertaken.
CONTROL PERFORMANCE OF VEHICLE ABS FEATURING ER VALVE PRESSURE MODULATOR
Authors: CHO M. S. , CHOI S. B. , WERELEY N. M.
Published: June 2005

In this work, an electrically controllable anti-lock brake system (ABS) for passenger vehicle is developed by utilizing electrorheological (ER) fluid. A pressure modulator which consists of a cylindrical ER valve and the hydraulic booster is constructed in order to achieve sufficient brake pressure variation during ABS operation. The principal design parameters of the modulator are determined by considering ER properties as well as required braking pressure. After investigating pressure controllability of the modulator, a vehicle model which is integrated with the proposed pressure modulator is formulated to design yaw rate controller. A sliding mode controller is designed to obtain desired yaw rate, and the friction forces between roads and wheels are estimated via the estimator. Braking performances of the proposed ABS under various roads are evaluated through the hardware-in-the-loop-simulation (HILS) and the steering stability during braking operation is demonstrated by undertaking split-μ test.
DYNAMIC PERFORMANCE OF CANTILEVER COMPOSITE MORTAR BEAMS WITH ELECTRO-RHEOLOGICAL FLUID
Authors: LU JINGZHOU , LI QINGBIN
Published: June 2005

The work presented in this paper bears on the feasibility and the operative technology of embedding electro-rheological (ER) fluids into cement mortar. We have made a cantilever mortar beam with controllable ER fluids filled in a central crack for the purpose of investigation on the evolutional rule of frequencies under different electric field strength by hammering test. The experimental results indicated that the influence of electric field strength upon the first frequency is more evident than that upon the second one, whereas that upon the third frequency is very little. In addition, the physical mechanism of the impact of the change of voltage on the frequency of smart beam structures embedded with ER fluids was discussed. This research sets up an experimental basis for the application of ER fluids in the domain of structural vibration control.
STUDY ON PROPERTIES OF ELECTRORHEOLOGICAL FLUID AND ITS APPLICATION IN MACHINING VIBRATION CONTROL
Authors: ZHANG YONGLIANG , YU JUNYI , HOU DONGXIA , ZHANG SHOUQIN , WU HUA
Published: June 2005

The better mechanical properties of Electrorheological fluid (ERF) are critical for its engineering application. In this paper, the effects of electric field strength and circumstance temperature on steady flow characteristic of ERF are analyzed; the effects of electric field strength, vibration amplitude, vibration frequency and circumstance temperature on ERF's dynamic mechanical properties are investigated using orthogonal tests. In addition, the ERF damper of lathe tool slide worked on shear-mode is developed; the turning experiments with the damper are performed in order to validate the suppressive effect of vibration. The experimental results demonstrate that ERF dampers can decrease the machining vibration response effectively.
EFFECTIVE THEORY FOR HIGH-TEMPERATURE SUPERCONDUCTIVITY BASED ON DUALITY AT S = 1/2 ANTIFERROMAGNETIC HEISENBERG MODEL
Authors: MORINARI TAKAO
Published: June 2005

It is argued that in two-dimension duality connects the CP1 representation of the S = 1/2 antiferromagnetic Heisenberg model with the Schwinger model in which Dirac fermions are interact via a U(1) gauge field. Application of this duality to underdoped high-temperature superconductors suggests that the high-energy fermionic excitation at the Mott insulating parent compound turns out to be a low-lying excitation in the spin disordered regime. A picture for high-temperature superconductivity is proposed.
STATIC AND SPONTANEOUS ELECTROWETTING
Authors: YEO LESLIE Y. , CHANG HSUEH-CHIA
Published: June 2005

There has been recent renewed interest in electrocapillary and electrowetting phenomena given its potential for microfluidic actuation and manipulation. Different approaches, in which a variety of electrode configurations have been adopted, however, have dominated the developments in this field. These different approaches have given rise to rich and varied behavior, which has often led to some overlap and confusion in the literature. In this article, we delineate the different observations and elucidate the relationship between these phenomena by re-stressing classical concepts and examining their limitations. Particular emphasis is placed on the distinction between static and spontaneous electrowetting. In the former, a static change in the liquid–solid macroscopic contact angle results when a dielectric film-coated planar plate electrode is employed. In the latter, a spontaneous thin fron-t-running electrowetting film is pulled out ahead of the macroscopic drop with the use of planar parallel line electrodes. This dynamically evolving electrowetting film advances much faster than the macroscopic drop itself and behaves in a self-similar manner analogous to gravity spreading films.
ANISOTROPIC PROPERTIES OF Bi-2201 THIN FILMS GROWN ON VICINAL SUBSTRATES
Authors: ZHANG Y. Z. , WANG Z. , ZHENG D. N. , WEN H. H. , ZHAO Z. X. , DE MARNEFFE J. F. , DELTOUR R. , JANSEN A. G. M. , WYDER P.
Published: June 2005

La doped Bi -2201 thin films were deposited on SrTiO 3 vicinal substrates with their (100) planes ~6° misoriented. The angular-dependent resistivity was studied in magnetic fields up to 23.5 T.
CHARACTERISTICS OF Y1-xCaxBa2Cu3O7-δ THIN FILMS GROWN BY DC MAGNETRON SPUTTERING
Authors: WANG Z. , ZHANG Y. Z. , LU X. F. , GAO H. , JIA S. L. , CHEN H. , WEN H. H.
Published: June 2005

Epitaxial Y 1-x Ca x Ba 2 Cu 3 O 7-δ thin films were successfully prepared by dc magnetron sputtering. The optimal deposition condition was determined. We find that the superconducting transition temperature Tc of thin films can be easily adjusted by annealing them in oxygen atmosphere with different pressures. Parabola curves are found for both Tc versus carrier concentration and Tc versus annealing pressure relations.
SPATIAL DISTRIBUTION OF SURFACE PLASMON POLARITON FROM METALLIC NANOSTRUCTURES
Authors: LUO XIANGANG , LV YUEGUANG , DU CHUNLEI , MA JUNXIAN , WANG HAO , LI HAIYING , YANG GAIRONG , YAO HANMIN
Published: June 2005

The spatial distribution of the interference of surface plasmon polariton (SPP) on metallic nanostructures has been studied. The results show that the transmission of electromagnetic radiation is remarkably enhanced for frequencies close to the surface plasmon band and the interference of SPP can redistribute the illumination light into subwavelength-scale spatial distribution with high intensity, which beats the Rayleigh diffraction limit. For an appropriate thickness, the transmission of an unperforated structure can be larger than that of holes or slits systems with the same periodicity and thickness when the coupled surface plasmon wave mode is excited. With the help of the interference of the horizontal plasmon excited by Bragg resonance due to the periodicity in the horizontal direction, the vertical plasmons, excited in z direction via Fabry–Perot cavity resonance in different grooves, are correlated, so the transmission is increased via the tunneling process. The properties of transparency for light but impenetrability for gas and liquid will be of importance for device applications. The information on near-field distribution from perforated metallic structures is important for understanding the underlying physics, as well as for optimizing photonic crystals for possible applications.
STRUCTURAL INSTABILITY AND SUPERCONDUCTIVITY OF THE (Nd, Gd, Ce)2CuO4 SYSTEM
Authors: POP A. V. , PELSHENKE C. , COZAR O.
Published: June 2005

The influence of partial substitution of Nd by Gd and Ce on the Nd 2 CuO 4n-type superconductor was studied by using X-ray diffraction measurements. For x = 0.15 Ce the maximum value of critical transition temperature Tc was obtained. The influence of Gd concentration on the lattice parameters and unit-cell volume was studied in the optimal doped sample (x = 0.15 Ce ) and in the samples with 0≤x≤0.2 Ce .

The relation between structural parameters and critical transition temperature was evidenced. The transition from the structural normal phase to the distortion phase was evidenced above y = 0.75 Gd in the optimal Ce -doped sample.
LOCALIZED EXCITONS IN SELF-ASSEMBLED InxGa1-xN QUANTUM DOTS
Authors: DAI XIAN-QI , HUANG FENG-ZHEN , SHI JUN-JIE
Published: June 2005

Within the framework of effective-mass approximation, the exciton states localized in cylindrical InGaN quantum dots (QDs) are investigated using a variational approach. The relationship between the exciton states and structural parameters of QDs with radius R and height L are studied in detail. The numerical results show that the exciton binding energy is sensitive to the ratio of R/L for a QD with a given volume. There is a maximum in the binding energy, where the electrons and holes are the most efficiently confined in the QDs with special structural parameters. The binding energy maximum can be obtained at about L = 1.7 nm for different QD volumes. The exciton binding energy and emission wavelength depend sensitively on structural parameters and the In content in the In x Ga 1-x N active layer. Our calculated emission wavelengths are in good agreement with experimental data.
OPTIMAL BURN-IN PROCEDURES IN A GENERALIZED ENVIRONMENT
Authors: CHA JI HWAN , MI JIE
Published: June 2005

Burn-in procedure is a manufacturing technique that is intended to eliminate early failures. In the literature, assuming that the failure rate function of the products has a bathtub shape the properties on optimal burn-in have been investigated. In this paper burn-in problem is studied under a more general assumption on the shape of the failure rate function of the products which includes the traditional bathtub shaped failure rate function as a special case. An upper bound for the optimal burn-in time is presented under the assumption of eventually increasing failure rate function. Furthermore, it is also shown that a nontrivial lower bound for the optimal burn-in time can be derived if the underlying lifetime distribution has a large initial failure rate.
A NOTE ON RELIABLE MULTICAST APPLYING CONVOLUTIONAL-CODE-BASED FEC OVER FINITE FIELD
Authors: ARAI MASAYUKI , FUKUMOTO SATOSHI , IWASAKI KAZUHIKO
Published: June 2005

We apply (n, k, m) convolutional codes in which elements in generator matrices are the ones over a finite field to Hybrid ARQ combining with retransmission mechanisms, and evaluate the number of transmitted packets and the number of transmissions. We assume star topology and independent model for a transmission model, and compare two retransmission strategies: (1) one which has been applied with Reed-Solomon (RS) code, and (2) one which choose transmitted packets considering the constraint length m. We use computer simulation for (14, 7, m) and (6, 3, m) convolutional codes to observe the effects of four parameters, that is the number of receivers, constraint length m, packet loss probability, and redundancy at initial transmission PF, to the number of transmissions and transmitted packets. Simulation results showed that the number of transmitted packets can be reduced by the retransmission mechanism which consider m. Also, a PF which minimize number of transmitted packets exists for given packet loss probability, number of receivers, and constraint length.
EFFICIENT COMPUTATION OF NETWORK RELIABILITY IMPORTANCE ON K-TERMINAL RELIABILITY
Authors: KOIDE TAKESHI , SHINMORI SHUICHI , ISHII HIROAKI
Published: June 2005

This paper proposes an algorithm to compute marginal reliability importance for network systems with k-terminal reliability efficiently. Marginal reliability importance is an appropriate quantitative measure on a system component against system reliability and it contributes to design of reliable systems. Computing marginal reliability importance in network systems is time-consuming due to its NP-hardness. This paper extends the algorithm proposed in our last study to deal with k-terminal reliability and incorporates an extended factoring theorem to improve the algorithm. Numerical experiments compare the proposed algorithm with a traditional method to reveal efficiency of the algorithm. The algorithm helps to construct efficient algorithm to reliable network design problems.
RELIABILITY AND MODELING OF SYSTEMS INTEGRATED WITH FIRMWARE AND HARDWARE
Authors: ZHANG TIELING , XIE MIN , TANG LOON CHING , NG SZU HUI
Published: June 2005

Firmware is embedded software in hardware devices and they play important role for many critical systems' function. Firmware failure rate in operation should be quite lower than the application software which is operating on it. Most of the study on software reliability deals with systems during development, and it is also important to study the integrated system during operation. Complex systems usually have a bathtub-shaped failure rate over the lifecycle of the product. This paper discusses the parametric analysis of model given by Haupt and Schäbe (1992), exponentiated Weibull distribution and models generated from Pareto and Weibull distribution, as well as their possible application to modeling firmware system failure. In addition, the Safety Integrity Levels (SIL) stipulated in IEC 61508 are taken into account in the modeling since the safety-critical systems in general are firmware-dominated.
A REPAIRABLE SYSTEM MODELLING: COMBINING GREY SYSTEM THEORY WITH INTERVAL-VALUED FUZZY SET THEORY
Authors: GUO R.
Published: June 2005

A fundamental but impossible to be addressed problem in repairable system modelling is how to estimate the system repair improvement (or damage) effects because of the large-sample requirements from the standard statistical inference theory. On the other hand, repairable system operating and maintenance data are often imprecise and vague and therefore Type I fuzzy sets defined by point-wise membership functions are often used for the modelling repairable systems. However, it is more logical and natural to argue that Type II fuzzy sets defined by interval-valued membership function, called interval-valued fuzzy sets (IVFS), should be used in characterizing the underlying mechanism of repairable system. In this paper, we explore a small-sample based GM(1,1) modelling approach rooted in the grey system theory to extract the system intrinsic functioning times from the seemly lawless functioning-failure time records and thus to estimate the repair improvement (damage) effects. We further explore the role of interval-valued fuzzy sets theory in the analysis of the system underlying mechanism. We develop a framework of the GM(1,1)-IVFS mixed reliability analysis and illustrate our idea by an industrial example.
Corporate Governance and the Challenges of Economic Transition: The Case of Shanghai Petrochemical Company
Authors: Tobin Damian
Published: June 2005

A case study of Shanghai Petrochemical Company (SPC) is used to analyse how economic reforms in China have impacted on corporate governance and enterprise performance. Reforms have increased the level of competition and altered the corporate structure of large state enterprises such as SPC. The case examines how SPC had responded to the opportunities and challenges created by the reform process. The case study indicates that despite changes in corporate structure, property rights remained unclear, resulting in a weakened corporate governance structure. Enterprise management had responded in an innovative way to the challenges of more competitive product markets. Improvements in areas such as efficiency, sales and management profile were largely a result of market-oriented reforms. However, weak property rights and a failure to integrate ownership and market reforms more effectively, had lessened the ability of SPC's management to fully exploit new business opportunities. Improvements in efficiency and sales had yet to be reflected in financial returns. This research case therefore indicates that a more integrated approach to enterprise reform is necessary for enterprises to benefit fully from economic liberalisation.
Performance Challenges at Masood Textile Mills
Authors: Iqbal Qureshi Zafar
Published: June 2005

Shahid Nazir, Chief Executive Officer of Masood Textile Mills in Faisalabad, Pakistan wanted to turn his company into one of the leading apparel companies in the world. To achieve this vision, Nazir wanted to transform his employees into what he called 'corporate athletes' through his vision and a more credible Performance Appraisal System. However, the results of an employee survey earlier in the year indicated that the company's performance appraisal was perceived by the employees to be subjective, inadequate and lacked credibility. This was of serious concern to Nazir. He therefore developed a new Performance Appraisal and Reward System. Implementation of the new system, however, was delayed temporarily due to the events of 9/11 and Nazir now aimed at its enforcement by mid 2002. He was of the opinion that the implementation of the new system would help in improving the motivation of his employees which, in turn, would lead to sustained high performance so essential to realize his vision. This case is useful in examining the design and implementation of an employee performance appraisal and reward system.
Turbulent Times at MoneyInc: Effects of Change in the New Zealand Public Sector
Authors: Ashwell Douglas
Published: June 2005

The late 1980's saw the New Zealand Government implement a number of radical economic reforms. As part of these reforms, a number of formerly public organisations were transformed into profit-making enterprises. These reforms resulted in large scale redundancies in a number of industries. During this time Rob joined MoneyInc a former publicly owned and operated financial institution, undergoing restructuring to become a State Owned Enterprise. The branch where Rob was employed was suffering from a number of redundancies and staff changes. Although a newcomer to the organisation and its culture, Rob quickly indicated his aspirations to be involved in the sales area of MoneyInc and was offered the job of Sales Officer by the branch management. At the time, this job was held by Mary a well respected and long-time employee of the branch. The manner in which this staff change was made led to a serious interpersonal conflict between Mary and Rob which affected the whole branch. This case can be used to examine issues related to staff job changes, such as trust, organisational culture and conflict management.
SingTel: Venturing into the Region
Authors: Heracleous Loizos , Singh Kulwant
Published: June 2005

In mid-2003, SingTel was at a key point in its history. The last decade had seen dramatic changes, as SingTel transformed itself from a Singapore-based government-owned telecommunications firm with no foreign operations and no domestic competition, to a credible regional competitor. By 2003, SingTel had invested more than $20 billion in substantial international operations in East and South Asia, Australia and Europe, and had survived perhaps the biggest collapse the telecommunications industry had ever suffered. SingTel was confident enough for its CEO, Lee Hsien Yang, to claim that the firm was "the leading communications company in Asia". Yet there were many doubts about its performance. SingTel was accused of lacking a clear strategy in its overseas ventures, of having overpaid for several of its overseas acquisitions, and most significantly, of having destroyed shareholder wealth. This case presents a brief outline of the main trends in the global and Singapore telecommunications industry and discusses SingTel's efforts to regionalize, with a focus on the Optus acquisition. The case ends with a call to evaluate the success of SingTel's regionalization efforts, in particular the Optus acquisition, and to discuss what SingTel's strategy should be for the future.
Mahut Group: A Failed Case of Organizational Restructuring
Authors: Som Ashok
Published: June 2005

Mahut Group (name disguised) was a family-owned business group that operated two cement companies, Heera and Moti (names disguised), in Gujarat, the Western part of India. Heera Cement had been making substantial losses since its inception and was currently under the consideration of Board of Industrial & Financial Reconstruction (BIFR). Moti Cement was also a loss-making company but the losses were not as substantial as that of Heera. Each of the cement companies, Heera and Moti, had a production capacity of 1.2 million tons of cement per annum. The Mahut Cement Group had about 1000 employees, out of which about 30 personnel were in the top management. As of 1999, both the cement companies competed with each other in addition to competing with other cement players operating in Gujarat. The cement industry was deregulated in India in the late 1980's which resulted in fierce competition and price wars among the cement firms. In the face of this fierce competition, the Group decided on a restructuring process, and hired an American consulting firm, in 1998, to find a "synergy" between the two companies, Heera and Moti, and help the two companies to turnaround. This case discusses the issues of the restructuring process and the various interventions undertaken by the top management of Mahut Group. The case discusses the recommendations of the consultant and the role of human resource management during the restructuring process.
L&T: Restructuring the Cement Business
Authors: Banerjee Ashok , Dwivedi Neeraj
Published: June 2005

The case describes one of the most hyped and controversial acquisition and de-merger episodes in Indian corporate history. The case involved two Indian diversified corporations: Grasim Industries Limited (Grasim) which belonged to the Aditya Birla group and a professionally managed Larsen and Toubro Limited (L&T). With an eye on exploiting possible synergies in the cement business, Grasim acquired a big chunk of shares of L&T and then went on to make an open offer for more shares. The case describes the situation and events unfolding after these developments with a view to highlight the intricacies involved in corporate restructuring through the process of demerger, such as, valuation, synergies, takeover defense and negotiations among various stakeholders.
Zinc finger transcription factor Egr-1 is involved in stimulation of NHE2 gene expression by phorbol 12-myristate 13-acetate
Authors: Malakooti Jaleh , Sandoval Ricardo , Memark Vanchad C. , Dudeja Pradeep K. , Ramaswamy Krishnamurthy
Published: June 2005

The apical membrane Na+/H+exchanger isoforms NHE2 and NHE3 are involved in transepithelial Na+absorption in the intestine. However, they exhibit differences in their pattern of tissue expression and regulation of their activity by various molecular signals. To study the mechanisms involved in the transcriptional regulation of these genes, we characterized cis-acting elements within the human NHE2 promoter that regulate NHE2 promoter expression in C2BBe1 cells. A small DNA region (−85/+249) was involved in the regulation of basal transcriptional activity of the NHE2 promoter as determined by transient transfection assays. RT-PCR analysis showed that NHE2 mRNA was upregulated in response to phorbol 12-myristate 13-acetate (PMA). Results from actinomycin D-treated cells indicated that the regulation of the NHE2 gene by PMA occurs in part at the transcriptional level. Furthermore, PMA treatment led to a 100% increase in promoter activity through elements located on the −415/+249 DNA fragment. A PMA-induced nuclear factor that bound to the NHE2 promoter was identified as the transcription factor Egr-1. We identified two PMA response elements in the −415/+1 promoter region that bind to Sp1 and Sp3 in untreated nuclear extracts and to Egr-1 in PMA-treated nuclear extracts. In cotransfection experiments, Egr-1 was able to transactivate the NHE2 promoter. Our data indicate that Egr-1 may play a key role in regulated expression of the human NHE2 gene.
Sensory peptide neurotransmitters mediating mucosal and distension evoked neural vasodilator reflexes in guinea pig ileum
Authors: Patton D. , O'Reilly M. , Vanner S.
Published: June 2005

The aim was to determine the role CGRP and/or tachykinins released from sensory neural mechanisms in enteric neural vasodilator pathways. These pathways project through the myenteric plexus to submucosal vasodilator neurons. Submucosal arterioles were exposed in the distal portion of an in vitro combined submucosal-myenteric guinea pig ileal preparation, and dilation was monitored with videomicroscopy. Vasodilator neural reflexes were activated by gently stroking the mucosa with a fine brush or by distending a balloon placed beneath the flat-sheet preparation in the proximal portion. Dilations evoked by mucosal stroking were inhibited 64% by the CGRP 8–37 and 37% by NK3(SR 142801) antagonists. When the two antagonists were combined with hexamethonium, only a small vasodilation persisted. Balloon distension-evoked vasodilations were inhibited by NK3antagonists (66%) but were not altered by CGRP 8–37. In preparations in which myenteric descending interneurons were directly activated by electrical stimulation, combined application of CGRP 8–37 and the NK antagonists had no effect. Stimulation of capsaicin sensitive nerves in the myenteric plexus did not activate these vasodilator reflexes. These findings suggest that mucosal-activated reflexes result from the release of CGRP and tachykinins from enteric sensory neurons. Distension-evoked responses were significantly blocked by NK3antagonists, suggesting that stretch activation of myenteric sensory neurons release tachykinins that activate NK3receptors on myenteric vasodilator pathways.
Pancreatic response to endotoxin after chronic alcohol exposure: switch from apoptosis to necrosis?
Authors: Fortunato Franco , Deng Xiaoying , Gates Lawrence K. , McClain Craig J. , Bimmler Daniel , Graf Rolf , Whitcomb David C.
Published: June 2005

Chronic alcohol consumption is known to increase the susceptibility to acute and chronic pancreatitis, and it is likely that a cofactor is required to initiate the progression to alcoholic pancreatitis. The severity and complications of alcoholic and nonalcoholic acute pancreatitis may be influenced by a number of cofactors, including endotoxemia. To explore the effect of a possible cofactor, we used endotoxin [lipopolysaccharide (LPS)] as a tool to induce cellular injury in the alcoholic pancreas. Single, increasing doses of endotoxin were injected in rats fed an alcohol or control diet and killed 24 h after the injection. We examined the mechanism by which LPS exacerbates pancreatic injury in alcohol-fed rats and whether the injury is associated with apoptosis or necrosis. We showed that chronic alcohol exposure alone inhibits apoptosis through the intrinsic pathway and the downstream apoptosis executor caspase-3 compared with the controls. Pancreatic necrosis and inflammation increased after LPS injection in control and alcohol-fed rats in a dose-dependent fashion but with a significantly greater response in the alcohol-fed animals. Caspase activities and TdT-mediated dUTP nick-end labeling positivity were lower in the alcoholic pancreas injected with LPS, whereas the histopathology and inflammation were more severe compared with the control-fed animals. Assessment of a putative indicator of necrosis, the ratio of ADP to ATP, indicated that alcohol exposure accelerates pancreatic necrosis in response to endotoxin. These findings suggest that the pancreas exposed to alcohol is more sensitive to LPS-induced damage because of increased sensitivity to necrotic cell death rather than apoptotic cell death. Similar to the liver, the pancreas is capable of responding to LPS with a more severe response in alcohol-fed animals, favoring pancreatic necrosis rather than apoptosis. We speculate that this mechanism may occur in acute alcoholic pancreatitis patients.
Glucocerebroside treatment ameliorates ConA hepatitis by inhibition of NKT lymphocytes
Authors: Margalit Maya , Ghazala Samir Abu , Alper Ruslana , Elinav Eran , Klein Athalia , Doviner Victoria , Sherman Yoav , Thalenfeld Barbara , Engelhardt Dean , Rabbani Elazar , Ilan Yaron
Published: June 2005

Concanavalin A (ConA) induces natural killer T (NKT) cell-mediated liver damage. Glucocerebroside (GC) is a naturally occurring glycolipid. Our aims were to determine the effect of GC in a murine model of ConA-induced hepatitis. Mice in groups A and B were treated with GC 2 h before and 2 h following administration of ConA, respectively; group C mice were treated with ConA; group D mice was treated with GC; group E mice did not receive any treatment. Liver damage was evaluated by serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and liver histology. The immune effect of GC was determined by fluorescence-activated cell sorter analysis of intrahepatic and intrasplenic NKT lymphocytes, measurement of cytokine levels, and Western blot analysis for STAT 1, 4, 6, and NF-κB expression. The effect of GC on NKT cell proliferation was assessed in vitro. Serum AST and ALT levels were markedly reduced in GC-treated group A mice compared with nontreated group C animals, and histological damage was markedly attenuated in group A. The beneficial effect of GC was associated with a 20% decrease of intrahepatic NKT lymphocytes, significant lowering of serum IFN-γ levels, and decreased STAT1 and STAT6 expression. In vitro administration of GC led to a 42% decrease of NKT cell proliferation in the presence of dendritic cells but not in their absence. Intraperitoneally administered radioactive GC was detected in the liver and bowel. Administration of GC led to amelioration of ConA hepatitis associated with an inhibitory effect on NKT lymphocytes. GC holds promise as a new immune-modulatory agent.
Role of mitochondria in aspirin-induced apoptosis in human gastric epithelial cells
Authors: Redlak Maria J. , Power Jacinda J. , Miller Thomas A.
Published: June 2005

This study was undertaken to determine whether the Bcl-2 family proteins and Smac are regulators of aspirin-mediated apoptosis in a gastric mucosal cell line known as AGS cells. Cells were incubated with varying concentrations of acetylsalicylic acid (ASA; 2–40 mM), with or without preincubation of caspase inhibitors. Apoptosis was characterized by Hoechst staining and DNA-histone-associated complex formation. Antiapoptotic Bcl-2, proapoptotic Bax and Bid, Smac, and cytochrome- c oxidase (COX IV) were analyzed by Western blot analyses from cytosol and mitochondrial fractions. ASA downregulated Bcl-2 protein expression and induced Bax translocation into the mitochondria and cleavage of Bid. In contrast, expression of Smac was significantly decreased in mitochondrial fractions of ASA-treated cells. Bax and Bid involvement in apoptosis regulation was dependent on caspase activation, because caspase-8 inhibition suppressed Bax translocation and Bid processing. Caspase-9 inhibition prevented Smac release from mitochondria. Additionally, increased expression of the oxidative phosphorylation enzyme COX IV was observed in mitochondrial fractions exposed to ASA at concentrations >5 mM. Although caspase-8 inhibition had no effect on aspirin-induced apoptosis and DNA-histone complex formation, caspase-9 inhibition significantly decreased both of these events. We conclude that Bcl-2 protein family members and Smac regulate the apoptotic pathway in a caspase-dependent manner. Our results indicate also that mitochondrial integration and oxidative phosphorylation play a critical role in the pathogenesis of apoptosis in human gastric epithelial cells.
Calcium dependence of proteinase-activated receptor 2 and cholecystokinin- mediated amylase secretion from pancreatic acini
Authors: Sharma Anupriya , Tao Xiaohong , Gopal Arun , Ligon Brooke , Steer Michael L. , Perides George
Published: June 2005

Pancreatic acini secrete digestive enzymes in response to a variety of secretagogues including CCK and agonists acting via proteinase-activated receptor-2 (PAR2). We employed the CCK analog caerulein and the PAR2-activating peptide SLIGRL-NH2to compare and contrast Ca2+changes and amylase secretion triggered by CCK receptor and PAR2 stimulation. We found that secretion stimulated by both agonists is dependent on a rise in cytoplasmic Ca2+concentration ([Ca2+]i) and that this rise in [Ca2+]ireflects both the release of Ca2+from intracellular stores and accelerated Ca2+influx. Both agonists, at low concentrations, elicit oscillatory [Ca2+]ichanges, and both trigger a peak plateau [Ca2+]ichange at high concentrations. Although the two agonists elicit similar rates of amylase secretion, the rise in [Ca2+]ielicited by caerulein is greater than that elicited by SLIGRL-NH2. In Ca2+-free medium, the rise in [Ca2+]ielicited by SLIGRL-NH2is prevented by the prior addition of a supramaximally stimulating concentration of caerulein, but the reverse is not true; the rise elicited by caerulein is neither prevented nor reduced by prior addition of SLIGRL-NH2. Both the oscillatory and the peak plateau [Ca2+]ichanges that follow PAR2 stimulation are prevented by the phospholipase C (PLC) inhibitor U73122, but U73122 prevents only the oscillatory [Ca2+]ichanges triggered by caerulein. We conclude that 1) both PAR2 and CCK stimulation trigger amylase secretion that is dependent on a rise in [Ca2+]iand that [Ca2+]irise reflects release of calcium from intracellular stores as well as accelerated influx of extracellular calcium; 2) PLC mediates both the oscillatory and the peak plateau rise in [Ca2+]ielicited by PAR2 but only the oscillatory rise in [Ca2+]ielicited by CCK stimulation; and 3) the rate of amylase secretion elicited by agonists acting via different types of receptors may not correlate with the magnitude of the [Ca2+]irise triggered by those different types of secretagogue.
Metabolic adaptations of liver mitochondria during restricted feeding schedules
Authors: Báez-Ruiz Adrián , Escobar Carolina , Aguilar-Roblero Raúl , Vázquez-Martínez Olivia , Díaz-Muñoz Mauricio
Published: June 2005

Food anticipatory activity (FAA) is an output of the food-entrained oscillator (FEO), a conspicuous biological clock that expresses when experimental animals are under a restricted food schedule (RFS). We have shown that the liver is entrained by RFS and exhibits an anticipatory response before meal time in its oxidative and energetic state. The present study was designed to determine the mitochondrial oxidative and phosphorylating capacity in the liver of rats under RFS to further support the biochemical anticipatory role that this organ plays during the food entrainment ( 9 ). Metabolic and functional parameters of liver mitochondria were characterized before (0800 h), during (1100 h), and after (1400 h) FAA. The main results were as follows. First, there was an enhancement during FAA (1100 h) in 1) oxidative capacity (site I of the electron transport chain), 2) phosphorylating ability (estimated by ATP synthesis), and 3) activities of NADH shuttles. Second, after rats were fed (1400 h), the phosphorylating capacity remained high, but this was not the case for the respiratory control ratio for site I. Finally, in the three experimental conditions before, during, and after FAA, an increment was detected in the H+electrochemical potential, due to an elevation in mitochondrial membrane potential, and in mitochondrial yield. Most of the changes in mitochondrial properties related to RFS were also present when results were compared with those from the 24-h fasted group. In conclusion, the results support the notion that a distinctive rheostatic state is installed in the metabolic activity of the liver when FEO is being expressed.
A subsidiary fever center in the medullary raphé?
Authors: Tanaka Mutsumi , McAllen Robin M.
Published: June 2005

In fever, as in normal thermoregulation, signals from the preoptic area drive both cutaneous vasoconstriction and thermogenesis by brown adipose tissue (BAT). Both of these responses are mediated by sympathetic nerves whose premotor neurons are located in the medullary raphé. EP3 receptors, key prostaglandin E2(PGE2) receptors responsible for fever induction, are expressed in this same medullary raphé region. To investigate whether PGE2in the medullary raphé might contribute to the febrile response, we tested whether direct injections of PGE2into the medullary raphé could drive sympathetic nerve activity (SNA) to BAT and cutaneous (tail) vessels in anesthetized rats. Microinjections of glutamate (50 mM, 60–180 nl) into the medullary raphé activated both tail and BAT SNA, as did cooling the trunk skin. PGE2injections (150–500 ng in 300–1,000 nl) into the medullary raphé had no effect on tail SNA, BAT SNA, body temperature, or heart rate. By contrast, 150 ng PGE2injected into the preoptic area caused large increases in both tail and BAT SNA (+60 ± 17 spikes/15 s and 1,591 ± 150% of control, respectively), increased body temperature (+1.8 ± 0.2°C), blood pressure (+17 ± 2 mmHg), and heart rate (+124 ± 19 beats/min). These results suggest that despite expression of EP3 receptors, neurons in the medullary raphé are unable to drive febrile responses of tail and BAT SNA independently of the preoptic area. Rather, they appear merely to transmit signals for heat production and heat conservation originating from the preoptic area.
Absence of cellular stress in brain after hypoxia induced by arousal from hibernation in Arctic ground squirrels
Authors: Ma Yi Long , Zhu Xiongwei , Rivera Patricia M. , Tøien Øivind , Barnes Brian M. , LaManna Joseph C. , Smith Mark A. , Drew Kelly L.
Published: June 2005

Although hypoxia tolerance in heterothermic mammals is well established, it is unclear whether the adaptive significance stems from hypoxia or other cellular challenge associated with euthermy, hibernation, or arousal. In the present study, blood gases, hemoglobin O2 saturation (So2), and indexes of cellular and physiological stress were measured during hibernation and euthermy and after arousal thermogenesis. Results show that arterial O2 tension (PaO2) and So2 are severely diminished during arousal and that hypoxia-inducible factor (HIF)-1α accumulates in brain. Despite evidence of hypoxia, neither cellular nor oxidative stress, as indicated by inducible nitric oxide synthase (iNOS) levels and oxidative modification of biomolecules, was observed during late arousal from hibernation. Compared with rats, hibernating Arctic ground squirrels ( Spermophilus parryii) are well oxygenated with no evidence of cellular stress, inflammatory response, neuronal pathology, or oxidative modification following the period of high metabolic demand necessary for arousal. In contrast, euthermic Arctic ground squirrels experience mild, chronic hypoxia with low So2 and accumulation of HIF-1α and iNOS and demonstrate the greatest degree of cellular stress in brain. These results suggest that Arctic ground squirrels experience and tolerate endogenous hypoxia during euthermy and arousal.
Endogenous central κ-opioid systems augment renal sympathetic nerve activity to maximally retain urinary sodium during hypotonic saline volume expansion
Authors: Gottlieb Helmut B. , Kapusta Daniel R.
Published: June 2005

Intracerebroventricular injection of κ-opioid agonists produces diuresis, antinatriuresis, and a concurrent increase in renal sympathetic nerve activity (RSNA). The present study examined whether endogenous central κ-opioid systems contribute to the renal excretory responses produced by the stress of an acute hypotonic saline volume expansion (HSVE). Cardiovascular, renal excretory, and RSNA responses were measured during control, acute HSVE (5% body weight, 0.45 M saline over 30 min), and recovery (70 min) in conscious rats pretreated intracerebroventricularly with vehicle or the κ-opioid receptor antagonist nor-binaltorphimine (nor-BNI). In vehicle-pretreated rats, HSVE produced a marked increase in urine flow rate but only a low-magnitude and delayed natriuresis. RSNA was not significantly suppressed during the HSVE or recovery periods. In nor-BNI-treated rats, HSVE produced a pattern of diuresis similar to that observed in vehicle-treated rats. However, during the HSVE and recovery periods, RSNA was significantly decreased, and urinary sodium excretion increased in nor-BNI-treated animals. In other studies performed in chronic bilateral renal denervated rats, HSVE produced similar diuretic and blunted natriuretic responses in animals pretreated intracerebroventricularly with vehicle or nor-BNI. Thus removal of the renal nerves prevented nor-BNI from enhancing urinary sodium excretion during HSVE. These findings indicate that in conscious rats, endogenous central κ-opioid systems are activated during hypotonic saline volume expansion to maximize urinary sodium retention by a renal sympathoexcitatory pathway that requires intact renal nerves.
Disuse atrophy increases the muscle mechanoreflex in rats
Authors: Hayashi Naoyuki , Koba Satoshi , Yoshida Takayoshi
Published: June 2005

We investigated the effect of disuse atrophy on the magnitude of the muscle mechanoreflex. The left leg of eight rats (6–7 wk, male) was put in a plaster cast for 1 wk. The rats were decerebrated at the midcollicular level. We recorded the pressor and cardioaccelerator responses to 30-s stretch of the calcaneal tendon, which selectively stimulated the muscle mechanosensitive receptors in the left atrophied and right control triceps surae muscles. Atrophied muscles showed significantly lower mass control muscles (1.0 ± 0.1 vs. 1.4 ± 0.1 g; P < 0.05). At the same stretch tension (229 ± 20 g), the pressor response to stretch was significantly greater in the atrophied muscles than in the control muscles (13 ± 3 vs. 4 ± 2 mmHg, P < 0.05). The cardioaccelerator response was not significantly different (8 ± 4 vs. 4 ± 2 beats/min). Comparing responses at the same relative tension (57 ± 6 vs. 51 ± 8% of maximal tension), the pressor response was still significantly greater in the atrophied triceps surae than in the control (14 ± 4 vs. 4 ± 2 mmHg; P < 0.05). These results suggest that disuse atrophy increases the magnitude of muscle mechanoreflex.