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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 57 (1991), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: : The weaver mutant mouse has a genetically determined defect in the nigrostriatal dopaminergic system. The present study was undertaken to test the hypothesis that in the weaver mutant mouse, striatal nerve terminals undergo compensatory changes in response to this deficiency. To test this hypothesis, we studied the basal and stimulated release of dopamine from striatal slices of weaver mutant mice and matched controls. By using a superfusion system and concentrating the superfusate by passage over alumina, resting dopamine release could be determined in the weaver mutant despite the fact that striatal tissue content of dopamine in these mice is reduced by 〉75% compared with control mice. Fractional resting release of dopamine in weaver striatal slices was significantly elevated compared with that in controls, suggesting that the release mechanisms in the weaver may be adapting to overcome the dopamine deficit. Potassium-evoked release (24 and 48 mM potassium) was not significantly different between the two genotypes. In contrast, amphetamine-evoked release (1 μM) was significantly greater in the weaver mice than in controls. In both genotypes, release evoked by amphetamine was completely inhibited by cocaine, implicating the dopamine uptake carrier in this release process. These findings suggest that fundamental differences in dopamine release mechanisms exist between weaver and control mice and support the hypothesis that compensatory mechanisms may develop in neurons in response to dopamine deficits.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5424-5426 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The isostructural uranium monopnictides and monochalcogenides have become prototype systems in actinide research with respect to their unusual magnetic properties. We have investigated the origins in the electronic structure of the variation in magnetic behavior as the degree of 5f-electron localization changes from localized to itinerant on going up the pnictogen or chalcogen column, thus decreasing the U-U separation. We have applied a synthesis of: (1) A phenomenological theory of orbitally driven magnetic ordering which includes both the hybridization-induced and the RKKY exchange interactions on an equal footing, and (2) Ab initio electronic structure calculations, based on the linear-muffin-tin-orbital method, allowing a first-principles evaluation of the parameters entering the model Hamiltonian. We have investigated systematically characteristic trends and changes of the 5f-state resonance width, the hybridization potential, and the hybridization-induced and RKKY exchange interactions with chemical environment, on going down the pnictogen or chalcogen column and on going from the weakly hybridizing pnictides to the more strongly hybridizing chalcogenides.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 5326-5335 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Equations of state for hard sphere chain molecules are derived within the framework of second order perturbation theory of polymerization (TPT2). The present formulation differs from the original Wertheim's treatment by dealing with molecules with a fixed number of beads. However, the two versions yield very close numerical results for chains composed of freely jointed spheres, showing the insensitivity of the pressure of these fluids to polydispersity. The case of star-like molecules and chain mixtures is also considered. Theoretical predictions are compared to available simulation data, using recent results for the triplet correlation function for hard spheres in rolling contact. Some predictions for the pressure of freely rotating chains and that of trimers as a function of the bond angle are given.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 721 (1994), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 26 (1993), S. 2524-2529 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 24 (1994), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. We report four cases of occupational asthma caused by chromium salts, three of whom showed dual and one isolated early asthmatic responses on specific chromium bronchoprovocation test (BPT). All of them were ex–smokers. Two showed positive skin–prick tests to 10mg/ml of Cr2(SO4)3, but negative results on patch testing. The remaining two showed positive results on patch testing with Cr2(SO4)3. Three had airway hyperresponsiveness to methacholine on initial examination. Although initial methacholine airway challenge testing showed a negative result in the remaining patient, airway hyperresponsiveness developed transiently 24 h after an isolated immediate asthmatic reaction induced by chromium. Three patients were reassessed after complete avoidance of chromium. Two subjects showed marked improvement of their symptoms with significant increases of PC20 methacholine. We conclude that chromium induces occupational asthma in exposed workers. Further investigations are needed to clarify the pathogenetic mechanism.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Shock waves 2 (1992), S. 245-254 
    ISSN: 1432-2153
    Keywords: Shock tube technique ; Detonation driver ; Gaseous detonation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics , Technology
    Notes: Abstract The concept of a shock tunnel with gaseous detonation driver is discussed. A detonation driver presents an alternative to a free-piston driver because comparable values of high enthalpy can be attained, however, without the fast movement of a heavy piston. Wave diagrams, pressure and temperature distributions are presented. Finally, first experimental results are given.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prostaglandin E2 (PGE2) at concentrations more than 1×10−8 M markedly suppressed the cell proliferation and release of soluble molecules of interleukin-2 receptor (sIL-2R), CD4 (sCD4) and CD8 (sCD8) from phytohemagglutinin (PHA)-stimulated normal human mononuclear cells (MNC) in a dose-related manner. To further elucidate the subcellular mechanism of the inhibitory effect of PGE2 on PHA-stimulated MNC, intracellular concentration of glutathione (GSH) in PHA-stimulated MNC was sequentially measured from day 1 to day 3 by enzymic method. Furthermore, the effect of PGE2 on nuclear DNA including DNA strand breaks in alkali treatment and DNA fragmentation (apoptosis) of PHA-stimulated MNC were also measured. We found intracellular GSH levels were significantly decreased in the early stage of lymphocyte activation (day 1), but no evidence of increased DNA stand breaks or apoptotic process appeared in 3-day culture. In addition, butathione sulfoximine (a specific GSH inhibitor) and dibutyryl cyclic AMP also exhibited both proliferation inhibition and GSH-decreasing effect on PHA-stimulated MNC as well as PGE2. These results suggest that the immunosupressive effect of PGE2 is mediated by the decreased generation of intracellular GSH, but not by the increased DNA strand breaks or apoptotic mechanism in the cells.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica solida Sinica 6 (1993), S. 81-97 
    ISSN: 0894-9166
    Keywords: finite deformation ; dilatant soil ; cavity expansion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract This paper considers large elastoplastic deformations of an internally pressurized hollow sphere of dilatant soil. A complete analytical solution for the expansion of a hollow sphere is developed. The soil is modelled as an elastic-perfectly plastic material obeying the Mohr-Coulomb yield criterion. A non-associated plastic flow rule is used and therefore the dilation of the material is fully taken into account. Closed form solutions are obtained for the stresses and the elastic-plastic deformations of arbitrary magnitude when a hollow sphere of soil is subjected to constant external pressure and monotonically increasing internal pressure. A selection of numerical results is presented to indicate the effects of various key parameters
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 16 (1972), S. 161-183 
    ISSN: 1432-1106
    Keywords: Facial nucleus ; Topographical representation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The facial nucleus (FN) of the cat was studied by electrophysiological method for (1) general characteristics of the FN neurons during antidromic activation, (2) topographical representation of the peripheral branches of the facial nerve and (3) synaptic activities induced in the FN neurons following peripheral facial nerve stimulation. Stimulation of either peripheral branches or the genu of the facial nerve produced negative field potential of 2–3 mV in the FN. The field potential had a latency of less than 1 msec, refractory period of 2–3 msec and a relatively short duration. During double shock testing of the antidromic field potentials, the test potentials were suppressed (after initial recovery from the refractory period) for a duration of up to 80–100 msec. Intracellular analysis revealed that antidromic firing of the FN neuron is composed of M, IS, SD spikes. The rise time of spike potentials ranged from 0.23 msec to 0.53 msec and fall time 0.73 msec to 4.7 msec. The duration of the spike after-hyperpolarization varied from 6 msec to 60 msec with latencies to peak of 1.5 msec to 14 msec. Double shock testing showed that the summation effect of the afterhyperpolarization was greater at shorter time intervals. The latencies of the spike potentials varied from 0.46 msec to 1.1 msec for peripheral nerve stimulation and 0.18 msec to 1 msec for genu stimulation. The conduction velocity of the facial nerve ranged from 25 m/sec to 75 m/sec. These results were compared with the known characteristics of other cranial and spinal motoneurons. Topographical representation of the peripheral branches of the facial nerve was that the PA was represented solely in the medial aspect, TZ mainly in the dorsal aspect of the intermediate portion and BL in the ventral aspect of the intermediate and mainly in the lateral aspect of the nucleus. Stimulation of peripheral facial nerve produced negative field potentials in the FN or induced EPSPs in the FN neurons with latencies of 4–7 msec. The synaptic inputs were found mainly in the medial aspect of the FN by PA stimulation. These synaptic inputs were discussed as being relayed through the trigeminal nucleus.
    Type of Medium: Electronic Resource
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