The effect of dopamine and PGI2 on indomethacin and alcohol-induced gastric lesions in rats of various ages in relation to gastric vascular permeability and HCl secretion

Gastric lesions induced by indomethacin (20 mg.kg-1 i.p.) and ethanol (1 ml 95% intragastrically) were studied in rats after a 24 hour fast. The size of gastric lesions was correlated with gastric HCl secretion and with gastric vascular permeability (determined from the Evan's blue concentration in the gastric tissue after its i.v. administration). These parameters were also studied in rats pretreated with either PGI2 (5 micrograms.kg-1) or dopamine (0.5 mg.kg-1). It was found that in 12-months old rats the gastric lesions were significantly higher compared with the 3-month old group. PGI2 and dopamine significantly decreased gastric lesions in the 3-month rats but not in 12-month old rats. Both indomethacin and ethanol increased gastric vascular permeability in both age groups. It was observed that the decrease of gastric lesions after pretreatment with PGI2 and dopamine in the 3-month old rats was followed with decreased gastric vascular permeability and HCl secretion. On the other hand the increased susceptibility of the gastric mucosa due to indomethacin in the 12-month old rats was followed by a decrease of HCl secretion. PGI2 or dopamine had any effect on the 12-month old rats. These results show that susceptibility of gastric mucosa to PGI2 and dopamine is dependent on age. (Fig. 3, Ref. 31.)     

Design of an isolated pig heart preparation for positron emission tomography and magnetic resonance imaging

RATIONALE AND OBJECTIVES: Validation of new positron emission tomography (PET) tracers or magnetic (MR) imaging contrast agents is based on isolated rodent heart preparations. The use of larger animals could provide a more direct validation using the devices used for humans. METHODS: An isolated pig heart preparation has been developed and adapted to the technical constraints of whole body PET and MR imaging. This preparation could be used either in the Langendorff or working mode after selective cannulation of both coronary arteries. RESULTS: The authors showed that quantification of regional kinetics of PET tracers was possible using this preparation by measuring fluorine-18-labeled deoxyglycose (18FDG) kinetics in remote and ischemic territories. Experiments using MR imaging contrast agents, for myocardial perfusion, demonstrated the ability of this preparation to accurately validate these contrast agents over a wide range of flow rates. CONCLUSIONS: An isolated pig heart preparation could be developed to fulfill the constraints of PET and MR imaging, and proved useful for the study of the distribution of different tracers or contrast media developed for functional cardiac imaging in humans.     

Supported nickel catalyst from hydroxycarbonate of nickel and aluminium

The hydroxycarbonate of nickel and aluminium (Ni/ Al = 3) with a hydrotalcite-like structure is an outstanding precursor of the active component of supported nickel catalysts. Good mechanical strength and suitable nickel content of these catalysts, which are necessary for practical applications, can be achieved by mechanical mixing of this compound with an additional support. The catalyst prepared from a mixture of 56.5 wt-% of nickel-aluminium hydroxycarbonate and 43.5 wt-% of γ-alumina was proven to have a stable catalytic activity in the methanation reaction at 2 MPa and 800 K.     

Application of substituted N-arylpyrroles in the corrosion protection of aluminium in hydrochloric acid

The inhibiting action of N-arylpyrroles on aluminium in 0.17 mol dm^–3 hydrochloric acid solution, in the temperature range 20–60 °C, was studied using potentiodynamic and electrochemical impedence spectroscopy techniques. The inhibiting efficiency of both investigated compounds 1-(2-fluorophenyl)-2,5-dimethylpyrrole (compound A) and 1-(2-fluorophenyl)-2,5-dimethylpyrrole-3-carbaldehyde (compound B) slightly increases with increasing temperature of the corrosive solution. Inhibitor adsorption on the elecrode surface decreases the apparent activation energy of the hydrogen evolution reaction. Compound A follows the Temkin adsorption isotherm, while its carbaldehyde derivative follows the Langmuir isotherm. The results of the apparent energy of activation and the standard free energy of adsorption point to stronger chemisorption of the compound A. However, due to additional condensation of molecules with carbaldehyde groups on the electrode surface, the carbaldehyde derivative exhibits even better inhibiting efficiency than compound A. The kinetic corrosion parameters, analysed in terms of the impedance data, show a satisfactory agreement with those obtained by the potentiodynamic method.     

Self-calibration based on invariant view recognition: Dynamic approach to navigation

We extend a dynamic approach of behavior generation to the representation of spatial information. Two levels of dynamics integrate dead-reckoning, dominant far from home bases, and piloting, dominant near home bases. When the view-based piloting system recognizes a home base, visual place information recalibrates the dead-reckoning system, inverting the hierarchical ordering of the two dynamic levels by time scale inversion. Reference views taken at discrete home bases are recognized invariantly under rotation of views. This process yields compass information. Continuous translational information is obtained as a neural place representation built from view correlations with a scattered set of local views. This self-calibrating cognitive map couples into a dynamics of heading direction integrating the behaviors of obstacle avoidance and target acquisition. Targets can be designated in terms of the cognitive map. We demonstrate the dynamical model in simulation.     

Agent-oriented techniques for network supervision

This paper presents the results of the Réseau futé (smart net) project, the goal of which is to use distributed AI and multi-agent techniques for network management and supervision. More precisely, these techniques have been applied to the partial automation of the dynamic processing (what is known about a network is always incomplete and can change at any time) of alarms and of various event notifications received by network management platforms. The system that we propose is able for example to automatically handle some alarms or to filter events of no-interest for a given operator. To achieve this goal, an assistant, or interface agent according to the model proposed by Patti Maes [MK93], has been realized. The goal of the assistant is first to learn, by observation, the behavior of the network supervision operator and second to reproduce such a behavior when the conditions in which the behavior has been learned are detected again. The learned information are stored using chronicles [Gha94]. A chronicle is a data-structure allowing programmers to represent sequences of events while taking temporal knowledge into account. Our assistant has been implemented and tested within Magenta which is a program, written in Smalltalk, that simulates (in a simplified way) a network management platform. This program respects roughly the gdmo and cmis standards.     

Portosystemic shunt in Budd-Chiari syndrome: long-term survival and factors affecting shunt patency in 25 patients in Western countries

BACKGROUND: In Budd-Chiari syndrome (BCS) treated by portosystemic shunt, postoperative shunt thrombosis is associated with high morbidity and mortality rates. The aim of this study was to determine factors associated with shunt thrombosis. METHODS: From 1985 to 1991, 25 patients underwent portosystemic shunt for BCS. According to the patency of the shunt during the postoperative period and follow-up, patients were divided into two groups including 17 patients with patent shunt and 8 (32%) with shunt thrombosis. RESULTS: In patients with patent shunt, actuarial survival rate at 5 years was 87% versus 38% in patients with shunt thrombosis (p < 0.05). Duration of symptoms before operation was higher in patients with shunt thrombosis than in patients with patent shunt (315 +/- 483 vs 109 +/- 168 days, p < 0.05). In patients with patent shunt, extensive fibrosis or cirrhosis was observed in 3 of 17 (18%) versus in 5 of 8 (63%) of patients with shunt thrombosis (p < 0.05). Shunt thrombosis was observed in 3 of 3 patients (100%) with the combination of myeloproliferative disorder, duration of symptoms more than 100 days, and cirrhosis versus 0 of 6 (0%) patients without this combination (p < 0.05). CONCLUSIONS: In acute form of BCS (with short history of the disease and absence of extensive fibrosis or cirrhosis), early portal decompression is mandatory, with low risk of shunt thrombosis and good long-term results. In chronic form of BCS, the risk of shunt thrombosis is high and long-term results are bad; in these patients, orthotopic liver transplantation must be considered.     

Reactive energy measurement using frequency controlled analog-to-pulse-rate converter

Contents This paper analyzes a problem of phase shifting and deseribes a novel method for electronic reactive energy measurement. The proposed measurement structure, composed of an integrator as a phase shifting circuit and a frequency controlled analog-to-pulse-rate converter, provides for the measurement completely in accordance with IEC definition of reactive energy, which is performed with simple but high performance metering device.

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Die Blindverbrauchsmessung anhand eines netzsynchronisierten Analog-Frequenz-Wandlers

Übersicht In diesem Artikel wird das Problem der Phasenverschiebung analysiert und eine neue Meßmethode für elektronische Blindverbrauschsmessung aufgezeigt. Die vorgeschlagene Strucktur, bestehend aus einem Integrator als Phasenschieber und netzkontrolliertem Analog-Frequenz-Wandler, ermöglicht die Verwirklichung eines einfachen aber präzisen Elektrizitätszählers zur Messung der Blindenergie, dessen Arbeitsprinzip mit den IEC Empfehlungen vollkommen übereinstimmt.