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  • 1
    Electronic Resource
    Electronic Resource
    Avoiding predation: alarm responses of Caribbean sea urchins to simulated predation on conspecific and heterospecific sea urchins (1986)
    Springer
    Marine biology 93 (1986), S. 201-208 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Alarm responses to the extracts of conspecifics and hetero-specifics were measured for the Caribbean sea urchins Echinometra viridis, E. lucunter, Lytechinus variegatus, L. williamsi, Tripneustes ventricosus, Diadema antillarum, and Eucidaris tribuloides collected along the Caribbean coast (9°33′14″N; 78°55′23″W) during October 1984 and July–December 1985. Responses to seawater and extracts of the gnathostomate echinoid Clypeaster sybdepressus were used as controls. The intensity of the response resulting from exposure to sea-urchin extracts was measured by: (1) the percentage of individuals that responded by moving away from the extract and/or towards shelter, and (2) the mean distance moved. Echinometra viridis, E. lucunter, and L. williamsi responded to sea-urchin extracts by moving towards nearby shelter sites. The distance that individuals of each species moved in the first minute following exposure to conspecific extracts was correlated with the distance that species moved from shelter while foraging. L. variegatus and D. antillarum, living in microhabitats not providing protection from predators, responded to extracts of conspecifics and heterospecifics by moving away from the direction of the extract. Eucidaris tribuloides did not exhibit alarm responses to the extracts of con- or hetero-specifics. E. tribuloides secures itself with its stout spines into protected sites within corals. Similarly, L. variegatus living in long, dense seagrass that provided protection from detection by predators, and D. antillarum occupying crevices, showed no alarm responses to extracts of conspecifics. Presumably, in these situations, sea urchins cannot increase their defenses against predation by moving away from an injured neighbor. T. ventricosus showed a weak response to extracts of L. variegatus, but no response to extracts of other species including conspecifics. The reasons for this lack of an alarm response are unclear. For the five species that demonstrated an alarm response to sea-urchin extracts, the intensity of the response varied depending on the type of extract used. L. variegatus, L. williamsi, and D. antillarum responded most strongly to extracts from conspecifics, while Echinometra viridis and E. lucunter responded strongly to extracts from both conspecifics and congeners. The weakest responses were shown to the extracts of T. ventricosus and Eucidaris tribuloides. Habitat overlap, overlap in predators, and phylogenetic relationships did not consistently explain patterns of alarm responses to the extracts of heterospecific sea urchins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00508257
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of physical structure on δI curves of longitudinal thin film (abstract) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4915-4915 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Conventionally, the simulation of thin films has been carried out using an HCP structure to represent its physical structure. Such an idealized structure has been shown to overestimate the effect of interparticle coupling by using an homogeneous exchange coupling scheme. A more realistic approach to represent physical structure has been undertaken by generating a system of grains which lie on a radially isotropic structure and have a nonuniform volume distribution. Interaction effects can be shown by computing δI curves formed through the comparison of the remanence curves using the Wohlfarth relation. To generate an isothermal remanence curve (IRM), a realistic ac erased state is necessary which has been carried out by using a simulated annealing technique. A comparison has been made to determine the effect of physical structure on the bulk properties by computing hysteresis loops, remanence curves, and δI curves. To reduce statistical error these have been averaged over four different sets of easy axes. The loops indicate that an irregular physical structure leads to an increase in the coercivity and decrease in the squareness. The dc-demagnetization curves show an increase in remanent coercivity; this can be attributed to the random physical structure decreasing the size of magnetically correlated regions within the microstructure. The effect of the physical microstructure on the δI curves will be discussed in full in the paper. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361585
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  • 3
    Electronic Resource
    Electronic Resource
    INHIBITION BY COCAINE OF NORADRENALINE RELEASE FROM SYMPATHETIC NERVES IN THE RABBIT EAR ARTERY (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 15 (1988), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: SUMMARY1. Effects of cocaine on release of noradrenaline (NA) from sympathetic nerves were studied in the isolated perfused central artery of the rabbit ear. Indices of release were the vasoconstrictor response to nerve stimulation and stimulation-induced overflow of radioactivity after the nerves had been loaded with [3H]-NA. The overflow studies were carried out on phenoxybenzamine-treated arteries to eliminate the effect of cocaine on neuronal uptake.2. Cocaine enhanced the constrictor responses of the artery to stimulation in concentrations of 3 and 30 μmol/l, but in higher concentrations (tested up to 300 μmol/l) the enhancement declined and was replaced by inhibition. Responses to extraluminal NA remained enhanced throughout the concentration range (tested up to 150 μmol/l).3. In contrast, cocaine depressed the overflow of radioactivity, the effect being detectable in a concentration of 3 μmol/l (a decrease of 15%); the decrease was 40% at the highest concentration tested (90 μmol/l).4. It is suggested that when assessed in terms of the vasoconstrictor response, inhibition of transmitter release by cocaine is masked by inhibition of neuronal uptake except in high concentrations of cocaine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1988.tb01120.x
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  • 4
    Electronic Resource
    Electronic Resource
    The mathematical modeling of the acquisition of gyroremanent magnetization in a single domain particle (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 4481-4483 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The origins of gyroremanent magnetization (GRM) in single domain particles are studied using a dynamic model based on the Landau–Lifschitz equation. The results show an asymmetry in the motion of the magnetic moment of a particle with three unequal axes of anisotropy. This asymmetry is interpreted in terms of an effective bias field which gives a good qualitative explanation of the origins of GRM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344888
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  • 5
    Electronic Resource
    Electronic Resource
    Cocaine-sensitive O-methylation of noradrenaline in dental pulp of the rabbit: Comparison with the rabbit ear artery (1987)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 335 (1987), S. 32-39 
    Details
    ISSN: 1432-1912
    Keywords: Rabbit dental pulp ; Ear artery ; Noradrenaline uptake ; Metabolism ; Cocaine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Incisor pulp from the rabbit metabolises exogenous noradrenaline in concentrations between 0.12 and 1.2 μmol/l mainly to NMN. Effects of chronic sympathetic denervation indicated that in incisor pulp the NMN is extraneuronal in origin, and that DOPEG and DOMA formation, as well as a major part of the noradrenaline which accumulates in the tissue, are associated with the sympathetic nerves. NMN formation was unaffected by hydrocortisone 210 μmol/l, but was strongly inhibited by cocaine 30 μmol/l. These effects contrasted with those in the rabbit ear artery, where NMN formation was increased by cocaine 30 μmol/l and decreased by hydrocortisone 210 μmol/l. In COMT-inhibited denervated pulp, cocaine inhibited the accumulation of noradrenaline. Monoamine fluorescence histochemistry of pulp exposed to noradrenaline 50 μmol/l indicated that cocaine-sensitive uptake occurred in fibroblasts. It is concluded that O-methylation of noradrenaline in dental pulp involves prior uptake of the amine by a process resembling uptake, but which is distinguished from uptake1 by its extraneuronal location.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00165032
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  • 6
    Electronic Resource
    Electronic Resource
    Differential effects of phosphonic analogues of GABA on GABAB autoreceptors in rat neocortical slices (1998)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 357 (1998), S. 408-412 
    Details
    ISSN: 1432-1912
    Keywords: Key words Rat neocortical slices ; GABABautoreceptors ; [3H]-GABA release ; GABAB receptor antagonists ; Phosphonic analogues of GABA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of five phosphonic derivatives of GABA on the release of [3H]-GABA from rat neocortical slices, preloaded with [3H]-GABA, were investigated. Phaclofen and 4-aminobutylphosphonic acid (4-ABPA) increased the overflow of [3H] evoked by electrical stimulation (2Hz) in a concentration-dependent manner, with similar potencies (phaclofen EC50=0.3mmol/l, 4-ABPA EC50=0.4mmol/l). At 3mmol/l, phaclofen increased the release of [3H]-GABA by 82.6±8.6%, and 4-ABPA increased the release by 81.3±9.0%. 2-Amino-ethylphosphonic acid (2-AEPA) increased the overflow of [3H] by 46.8±10.9% at the highest concentration tested (3mmol/l). In contrast, the lower phosphonic homologue 3-aminopropylphosphonic acid (3-APPA), and 2-amino-2-(p-chlorophenyl)-ethylphosphonic acid (2-CPEPA), a baclofen analogue, did not modify the stimulated overflow. These results suggest that phaclofen, 4-ABPA and 2-AEPA are antagonists at GABAB autoreceptors, the latter being the weakest antagonist, whilst neither 3-APPA nor 2-CPEPA are active at these receptors. Since phaclofen, 4-ABPA and 2-CPEPA are antagonists and 3-APPA a partial agonist/antagonist on GABAB heteroreceptors, the lack of effect of 3-APPA and 2-CPEPA on [3H]-GABA release in this study suggests that GABAB autoreceptors may be pharmacologically distinct from the heteroreceptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005186
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  • 7
    Electronic Resource
    Electronic Resource
    Evidence for uptake2-mediated O-methylation of noradrenaline in the human amnion FL cell-line (1993)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 347 (1993), S. 371-378 
    Details
    ISSN: 1432-1912
    Keywords: Human amnion FL cells ; Noradrenaline ; Uptake2 ; O-methylation ; Papaverine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The uptake and metabolism of 3H-noradrenaline has been examined in the FL cell-line derived originally from human amnion. Cell cultures metabolised 3H-noradrenaline (1.0 μmol/l) to 3H-normetanephrine and, to a lesser extent, to metabolites (not distinguished) of the O-methylated deaminated fraction; primary deaminated metabolites were not detected. 3(H-normetanephrine formation a) was not saturable in the noradrenaline concentration range 0.2–150 μmol/l, b was decreased to 20%–30% of control levels by uptake2 inhibitors (O-methylisoprenaline, 20 and 100 μmol/l; cimetidine, 10 μmol/l; hydrocortisone, 200 μmol/l) and c, was almost insensitive to uptake1 inhibitors (cocaine, 30 μmol/l; desipramine, 3 μmol/l). Uptake of noradrenaline was manifested after 30 minutes as a 6-fold increase in the cell content of the amine following inhibition of catechol-O-methyl transferase, either alone or in conjunction with inhibition of monoamine oxidase. Uptake was decreased maximally to 40% of control levels by O-methylisoprenaline. IC50 values for inhibition of the O-methylisoprenaline-sensitive component of uptake were (in μmol/l): corticosterone (0.3), papaverine (1.1), O-methylisoprenaline (3.0), cimetidine (6.0), (−)noradrenaline (460), and tetraethylammonium (2230). Except for the last agent, for which a comparative value is not available, the IC50's are in good agreement with those for inhibition of uptake2 in the Caki-1 cell-line reported by other investigators. The component of uptake resistant to O-methylisoprenaline was depressed by papaverine (a 50% decrease at 50 μmol/l), but was not affected by the other uptake2 inhibitors or by cocaine (30 μmol/l). It is concluded that the FL cell possesses an extraneuronal metabolising system very similar to the system in tissues such as heart and smooth muscle where transport of noradrenaline into the cell by uptake2 is followed by rapid O-methylation via catechol-O-methyl transferase. The only difference appears to be the absence of saturation of 3H-normetanephrine formation in the FL cell at low micromolar concentrations of 3H-noradrenaline. The presence of a second uptake process is suggested by the inhibitory effect of papaverine on uptake resistant to O-methylisoprenaline; lack of effect of cocaine implies that this second process is not uptake,.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00165386
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  • 8
    Electronic Resource
    Electronic Resource
    Extraneuronal uptake of noradrenaline in rabbit dental pulp: evidence of identity with uptake (1992)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 346 (1992), S. 166-172 
    Details
    ISSN: 1432-1912
    Keywords: Dental pulp ; Noradrenaline ; Extraneuronal uptake1 ; O-methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The extraneuronal removal and disposition of noradrenaline in rabbit dental pulp was examined in view of earlier evidence that the tissue possessed an extra-neuronal uptake process resembling neuronal uptake1. Pulp, which had been depleted of sympathetic nerves by homolateral superior cervical ganglionectomy, was incubated in vitro with 3H-noradrenaline in low concentrations (0.025 or 0.18 μmol/l). When the metabolising enzymes (monoamine oxidase, catechol-O-methyl transferase) were active, 3H retention by the denervated pulp, as indicated by the 3H content after the tissue had been washed for 30 min following incubation with 3H-noradrenaline, was less than 30% of that of the innervated pulp. When the enzymes were inhibited, retention rose to approximately 30% of that of the innervated pulp. Analysis of the time course of the 3H efflux indicated that the 3H-noradrenaline in the denervated pulp had accumulated in a single compartment characterised by a t1/2 for efflux of several hours. Accumulation did not occur under Na+-free conditions, and was inhibited by desipramine (IC50 〈 0.03 μmol/l) and by substrates of neuronal uptake1. Mean IC50, values of the latter were very similar to those for inhibition of neuronal uptake1 and comprised (in μmol/l): (+)amphetamine (0.29), dopamine (0.31), tyramine (0.39), (−)noradrenaline (0.70), (−)adrenaline (1.50), 5-hydroxytryptamine (20) and bretylium (35). Uptake2 inhibitors were less active (O-methyl isoprenaline, IC50 = 60 μmol/l) than uptake1 inhibitors, or were without inhibitory effects at the concentrations tested (hydrocortisone, 210 μmol/l; 2-methoxy oestrone, 10 μmol/l). The effects of Na+ omission, of (+)amphetamine, and of O-methylisoprenaline on 3H-normetanephrine formation (measured in the absence of catechol-O-methyl transferase inhibition) matched their effects on 3H-noradrenaline accumulation. The results provide strong support for the presence in rabbit dental pulp of extraneuronal uptake1 which is linked with catechol-O-methyl transferase in the removal of noradrenaline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00165298
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of 6-hydroxydopamine on noradrenaline metabolism linked to neuronal uptake1 and extraneuronal uptake1 in dental pulp in vitro (1994)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 350 (1994), S. 352-355 
    Details
    ISSN: 1432-1912
    Keywords: Human dental pulp ; Rabbit dental pulp ; Noradrenaline metabolism ; 6-Hydroxydopamine ; Uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The study was undertaken to determine the relative roles of neuronal and extraneuronal uptake1 in the metabolism of 3H-noradrenaline in human dental pulp. Rabbit dental pulp was used as a reference since it was already known that normetanephrine (NMN) formation in this tissue utilised extraneuronal uptake,. Slices of pulp were preincubated in the absence and presence of 6-hydroxydopamine (1.6 mmol/l, for 10 or 20 min at pH 4.5) and subsequently incubated with 3H-noradrenaline (0.18 μmol/l for 30 min at pH 7.4). The principal metabolites formed were normetanephrine in rabbit pulp and deaminated catechols (dihydroxymandelic acid and dihydroxyphenylglycol) in human pulp. In both tissues 6-hydroxydopamine strongly inhibited formation of the deaminated catechols, but was without effect on normetanephrine formation. It is concluded that: i) in vitro 6-hydroxydopamine does not influence the metabolic process which is dependent on extraneuronal uptake1, namely normetanephrine formation in rabbit dental pulp, and in human pulp. Attention is drawn to an unusual feature of the neuronal metabolism in human pulp, namely the appearance of dihydroxymandelic acid as the principal metabolite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178950
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  • 10
    Electronic Resource
    Electronic Resource
    Modification by dipyrone (noramidopyrine methanesulphonate) of stone-induced ureteric hyperperistalsis in the dog (1979)
    Springer
    Urological research 7 (1979), S. 13-17 
    Details
    ISSN: 1434-0879
    Keywords: Ureteric colic ; Dipyrone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Implantation of a stone in the ureter of the dog by ureterotomy results in focal hyperperistalsis which is accentuated by administration of norepinephrine, and reduced by administration of phenoxybenzamine or isoproterenol. Administration of dipyrone reduces the hyperperistalsis, but this action does not appear to be that of either a β-agonist or an α-antagonist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262920
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