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  • Electroconvulsive shock  (5)
  • Physical Chemistry  (4)
  • Engineering  (3)
  • 1
    ISSN: 1432-2072
    Keywords: Electroconvulsive shock ; Corticosterone ; Muscarinic agonists ; Serotoninergic agonists ; α-Adrenoceptor agonists ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of repeated and single electroconvulsive shocks (ECS) on the corticosterone response to pharmacological stimuli has been studied in male rats. Plasma corticosterone concentrations are elevated by oxotremorine, a muscarinic agonist, and by 5-hydroxy-l-tryptophan, a precursor of serotonin. Both these agonists probably stimulate corticotrophinreleasing-factor release from the hypothalamus. The log dose-response curves of the corticosterone response to oxotremorine and to 5-hydroxy-l-tryptophan are shifted to the left after a single ECS given daily for 10 days compared with sham-shocked controls. Plasma corticosterone concentrations are elevated by treatment with α-methyl-p-tyrosine methyl ester (400 mg/kg IP). This rise is suppressed by clonidine. The log dose-response curve for the corticosterone response to clonidine after α-methyl-p-tyrosine methyl ester is also shifted to the left by repeated ECS, compared with controls. There is no difference in the corticosterone response of ECS and sham-treated groups given vasopressin, which is thought to act directly on the pituitary to release ACTH. A single ECS produces a slight enhancement of the response to 5-hydroxy-l-tryptophan, a slight decrease in the response to oxotremorine and no change in the response to clonidine after α-methyl-p-tyrosine. The disappearance of the difference in response between ECS and sham-treated animals was also studied 1,3, and 6 days after a series of ten ECS or sham procedures. Significant differences in the corticosterone responses to oxotremorine, 5-hydroxy-l-tryptophan and clonidine after α-methyl-p-tyrosine between ECS and sham-treated animas were found 24 h after the last ECS or sham shock. These differences were in decline 3 days after the last procedure and had completely disappeared by day 6. The decline was largely due to an increase in plasma corticosterone responsiveness to pharmacological stimuli of the shamshocked controls. Responses in the ECS-treated groups remained constant. It is apparent that the anaesthetic procedure suppresses the effect of oxotremorine, 5-hydroxy-l-tryptophan and clonidine after α-methyl-p-tyrosine on corticosterone concentrations in plasma. This effect is spontaneously reversible. Repeated ECS reverses the effect of the anaesthetic procedure but produces no reversible enhancement of its own.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2072
    Keywords: Electroconvulsive shock ; Electronvulsive therapy ; 5-Hydroxytryptamine ; Behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Treatment of rats with one electroconvulsive shock (ECS) per day for 10 days enhanced the hyperactivity syndrome produced by administration of tranylcypromine (10 mg kg-1) and l-tryptophan (50 mg kg-1) given 24 h after the final shock. Similar enhancement was seen whether the shock was alternating sinusoidal or direct current (fractionated), whether it was given through unilaterally or bilaterally placed electrodes and whether or not a neuromuscular blocking agent (fazadinium) was used. Five shocks spread over 10 days or 8 shocks spread over 17 days were similarly effective, whilst 8 shocks in 1 day were ineffective. Therefore when ECS are given to rats in ways similar to those in which electroconvulsive therapy is given to patients with depression, enhancement of behavioural responses to increased 5-HT function is produced.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2072
    Keywords: Electroconvulsive shock ; Growth hormone ; Clonidine ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of repeated electroconvulsive shocks (ECS) on growth hormone (GH) secretion was studied in rats. Male Sprague-Dawley animals were given one ECS daily for 10 days under halothane anaesthesia. Control animals were anaesthetised only. GH secretion was studied 24 h after the last ECS or sham procedure. Background GH secretion was significantly greater in ECS-treated than in sham-treated animals (P〈0.001). The GH response to IV clonidine (0.01–0.1 mg/kg) did not differ between the two groups. The size of the GH response was not directly related to the basal GH secretion and could not be explained in terms of it.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 101 (1990), S. 110-114 
    ISSN: 1432-2072
    Keywords: Electroconvulsive shock ; Dopamine receptor subtypes ; SKF 38393 ; RU 24213 ; Apomorphine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study examined the effect of acute and repeated administration of electroconvulsive shock (ECS) on behaviours induced by various dopamine agonists in rats. Components of behavioural arousal induced by the dopamine D-1 agonist SKF 38393, the dopamine D-2 agonist RU 24213 and the mixed D-1/D-2 agonist apomorphine were assessed using a behavioural check-list method. Also, the overall behavioural syndrome produced by these drugs was measured using rating scales. Rats receiving repeated (5 times over 10 days) but not a single ECS showed enhanced grooming and sniffing in response to SKF 38393 (7.5 mg/kg) when compared to controls. Repetitive sniffing induced by apomorphine (0.5 mg/kg) was also enhanced by repeated ECS. Neither repeated nor a single ECS significantly changed behaviours induced by RU 24213 (0.75 mg/kg), although a downward trend was evident. The behaviour rating scale measurements also demonstrated that repeated administration to ECS increased behavioural responsiveness to SKF 38393 and apomorphine but not RU 24213. These results suggest that the increase of dopamine-mediated behaviour in rats seen after chronic ECS relates to an increase in central dopamine D-1 receptor function.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2072
    Keywords: Electroconvulsive shock ; 5-Hydroxytryptamine ; Dopamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Following repeated electroconvulsive shocks (ECS) (once daily for 10 days), rats display enhanced hyperactivity responses to tranylcypromine and l-tryptophan, a procedure which increases brain 5-hydroxytryptamine (5-HT) concentrations, or to the suggested 5-HT agonist quipazine. The enhanced responses last for about 6 days following the last shock. Repeated sub-convulsive shocks did not produce this behavioural enhancement. Administration of indomethacin (2 mg/kg) 25 min before the ECS did not prevent the enhanced 5-HT response suggesting that the enhanced response is not the result of the reported rise in prostaglandins F following ECS. Repeated ECS shortened the time to loss of righting following pentobarbital (50 mg/kg) but did not alter the total sleeping time. Repeated ECS enhances locomotor activity produced by methamphetamine. It also enhances circling produced by methamphetamine and apomorphine in unilateral nigrostriatal lesioned rats, suggesting an enhanced postsynaptic response. No evidence was found for ECS altering the response of striatal adenylate cyclase to dopamine nor for any alteration of striatal cyclic AMP concentration. These data taken with our previous study reinforce the suggestion that electroconvulsive therapy (ECT) produces increased responses to 5-hydroxytryptamine and dopamine receptor stimulation.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 7 (1973), S. 137-154 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper shows how analytic surfaces can be used to define the vanes of an impeller of a centrifugal compressor. The analysis has been given of a cubic-linear patch for representing three-dimensional geometries. An example has shown how this type of patch can be successfully used to model the geometry of centrifugal or mixed flow impellers having 'swept back vanes at the outlet.The analysis has been programmed for the Atlas computer at the Computer Aided Design Centre (CADC), Cambridge and set up in such a way that the designer can examine systematically a range of impeller shapes.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 13 (1989), S. 283-302 
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A simple and efficient method for the solution of uncoupled transient thermoelastic problems using boundary integral techniques is presented. The method employs a Laplace transformation to remove temporarily the time dependence of the governing equations. Numerical analysis is then carried out in the transform space, and results in the time-position space are found by numerical inversion of the Laplace transform. The method has the advantage that it avoids time-stepping and the costly evaluation of domain integrals. Boundary element and analytic solutions are compared, and the effect of cooling on the stresses around a deep underground opening is examined.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 20 (1996), S. 457-488 
    ISSN: 0363-9061
    Keywords: Linear thermo-poro-elastic materials ; boundary element method ; Green's functions ; Dirac delta functions ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: This paper presents a direct boundary element method of numerical analysis, formulated in the Laplace transform domain, for a plane strain analysis of a linear thermo-poro-elastic material consolidating in the presence of a heat source. The equations governing the behaviour of the material are assumed to be a set of self-adjoint and fully coupled linear equations. A physical intepretation of the constants appearing in the linear theory relevant to engineering applications is presented. A boundary integral equation is developed from the governing equations in a straightforward way using the properties of Dirac delta functions, and an approximate boundary element method of numerical analysis is implemented using the Green's functions derived previously by the authors. The numerical analysis presented is motivated by the engineering design of a heat generating radioactive waste repository located deep underground. For this reason, there is a description of the application of the boundary integral equation method presented to the numerical solution of several problems of theoretical and practical interest in the area of radioactive waste disposal in clay-like soils.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 24 (1992), S. 199-215 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethyl tertiary butyl ether (ETBE) is being proposed as an additive for use in reformulated gasolines. In this study, experiments were performed to examine the kinetics and mechanism of the atmospheric removal of ETBE. The kinetics of the reaction of ETBE with OH radicals were examined by using a relative rate technique with the photolysis of methyl nitrite to generate OH radicals. With n-hexane as the reference compound, a value of (9.73 ± 0.33) × 10-12 cm3 molecule-1 s-1 was obtained for the rate constant. The OH rate constant for t-butyl acetate, a product of the oxidation of ETBE, was (4.4 ± 0.4) × 10-13 cm3 molecule-1 s-1 at 298 K.The primary products and molar yields for the OH reaction with ETBE in the presence of NOx were t-butyl formate (0.64 ± 0.03), t-butyl acetate (0.13 ± 0.01), ethyl acetate (0.043 ± 0.003), acetaldehyde (0.16 ± 0.01), acetone (0.019 ± 0.002), and formaldehyde (0.53 ± 0.04). Under the described reaction conditions, the formation of t-butyl nitrite was also observed. From these molar yields, approximately 98% of the reacted ETBE could be accounted for by paths leading to these products. Chemical mechanisms to explain the formation of these products are presented.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 23 (1991), S. 907-924 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl tertiary butyl ether (MTBE) has been proposed and is being used as an additive to increase the octane of gasoline without the use of tetraethyl lead and alkylbenzenes. The present experiments have been performed to examine the kinetics and mechanisms of the atmospheric removal of MTBE. The kinetics of the reaction of OH with MTBE was examined by using a relative rate technique in which photolysis of methyl nitrite was used as the source of OH. With n-butane as the reference compound a value of (2.99 ± 0.12) × 10-12 cm3 molecule-1 s-1 at a temperature of 298 K was obtained for the rate constant. The products (and product yields) for the OH reaction with MTBE in the presence of NOx were also determined and found to be t-butyl formate (0.68 ± 0.05), methyl acetate (0.14 ± 0.02), acetone (0.026 ± 0.003), t-butanol (0.062 ± 0.009), and formaldehyde (0.48 ± 0.05) in mols/mol MTBE converted. The OH rate constant for the major product formed, t-butyl formate was also measured and found to be (7.37 ± 0.05) × 10-13 cm3 molecule-1 s-1. Mechanisms to rationalize the formation of the products are presented.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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