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  • 1
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A general feature of motor patterns for locomotion is their cyclic and alternating organization. In walking, for example, rhythmic activity in leg motoneurons innervating antagonistic muscles of a joint is primarily antiphasic within each cycle. We investigate which role central pattern generating networks play in the generation of leg motoneuron activity in the absence of sensory feedback. We elicited activity in antagonistic flexor and extensor tibiae motoneurons in the deafferented mesothoracic ganglion of the stick insect by mechanically stimulating the head or abdomen, while recording intracellularly from their neuropilar processes. In most cases, tactile stimulation induced coactivation of tibial motoneurons. However, in ≈ 25% of the trials, tibial motoneurons generated alternating cycles consisting of bursts of action potentials that were terminated by strong inhibitory synaptic inputs. Injection of depolarizing current increased the amplitude of the inhibitory phase of the oscillation, while hyperpolarizing current decreased it and revealed a tonic depolarization of the motor neurons during the bout of rhythmic motor activity. The same results were gathered from recording tibial leg motoneurons during ‘twitching’ motor activity in decerebrated animals. Our results indicate that alternating rhythmic motoneuron activity in the deafferented stick insect walking system results from phasic inhibitory drive provided by central pattern generating networks. This inhibitory input patterns the firing of the motoneurons that results from a tonic depolarizing drive. This tonic depolarizing drive was also observed in tibial motoneurons of the deafferented mesothoracic ganglion during walking movements of the intact ipsilateral front leg.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 11 (1999), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neuronal activity may lead to a variety of responses in neighbouring glial cells; in general, an ensemble of neurons needs to be active to evoke a K+- and/or neurotransmitter-induced glial membrane potential change. We have now detected a signal transfer from a single neuromodulatory Leydig neuron to the giant neuropil glial cells in the central nervous system of the leech Hirudo medicinalis. Activation of a Leydig neuron, two of which are located in each segmental ganglion, elicits a hyperpolarization in the giant neuropil glial cells. This hyperpolarization could be mimicked by bath application of the peptide myomodulin A (1 nm–1.0 μm). Myomodulin-like immunoreactivity has recently been found to be present in a set of leech neurons, including Leydig neurons (Keating & Sahley 1996, J. Neurobiol., 30, 374–384). The glial responses to Leydig neuron stimulation persisted in a high-divalent cation saline, when polysynaptic pathways are suppressed, indicating that the effects on the glial cell were direct. The glial responses to myomodulin A application persisted in high-Mg2+/low-Ca2+ saline, when chemical synaptic transmission is suppressed, indicating a direct effect of myomodulin A on the glial membrane. The glial hyperpolarization evoked by myomodulin A was dose dependent (EC50 = 50 nm) and accompanied by a membrane conductance increase of ≈ 25%. Ion substitution experiments indicated that myomodulin A triggered a Ca2+-independent K+ conductance. Thus, our results suggest, for the first time, direct signal transmission from an identified modulatory neuron to an identified glial cell using a myomodulin-like peptide.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 242 (1962), S. 437-449 
    ISSN: 1432-1912
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung In der vorliegenden Arbeit wird über die Beeinflussung der Hexobarbitalnarkose durch intracerebrale Injektion von Reserpin, sowie von Noradrenalin oder Serotonin vor und nach intraperitonealer Reserpinapplikation berichtet. Die Injektion von Reserpin in das Vorderhirn verändert die Narkosedauer nicht signifikant, nach Injektion in das Hinterhirn kommt es zunächst zu einer Verkürzung der Narkose, die dann von einer Verlängerung abgelöst wird. Die narkoseverlängernde Wirkung von Noradrenalin und die verkürzende Wirkung von Serotonin bei Injektion in das Hinterhirn wird durch Reserpin qualitativ nicht verändert. Im Gegensatz dazu wird die narkoseverlängernde Wirkung von Noradrenalin oder Serotonin bei Injektion in das Vorderhirn im Verlauf der Reserpinwirkung in einen narkoseverkürzenden Effekt umgewandelt. Dabei erweisen sich bereits 0,5 nm Noradrenalin als wirksam. Die möglichen Wirkungsmechanismen der untersuchten Substanzen werden diskutiert, wobei der Relation zwischen freiem und gebundenem Amin besondere Bedeutung beigemessen wird.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 43 (1965), S. 562-569 
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary A total of 27 children of a nursery-home, 10 to 14 years of age at the date of their vaccination received a monovalent immunization with poliovirus type I, and, about 5 weeks later, a bivalent one with types II and III, orally. All the 3 types provoked a significant increase in titers of the neutralizing antibodies, though the immunizing effect of type III was less efficient due to interferential phenomena apparently. In the neutralizing test, children without any prevaccinal antibodies yielded a greater rate of increase in antibodies of types I and II than children with prevaccinal antibodies. But ultimately, all of the probatory individuals possessing antibodies already before their vaccination attained a higher average of titer-values in all of the 3 types. In addition to an expected increase in homologous antibodies, an increase in heterologous neutralizing antibodies could be observed in 37 per cent of the children examined as directed against type II, and in 41 per cent as directed against type III. Complement-fixing homologous antibodies were traceable with type I in 51.8, with type II in 34.8, and with type III in 21.3 per cent of the cases. A formation of heterologous complement-fixing antibodies could be observed only once. The results were discussed, among others, especially with regard to the dates of the respective extractions of blood.
    Notes: Zusammenfassung Es wurden insgesamt 27 Kinder eines Heimes, die zum Zeitpunkt der Impfung 10 bis 14 Jahre alt waren, monovalent mit Poliovirus Typ I und etwa 5 Wochen später bivalent mit den Typen II und III oral immunisiert. Gegen alle drei Typen trat ein signifikanterTiteranstieg der neutralisierenden Antikörper auf, wobei jedoch der Immunisierungseffekt des Typs III, offenbar infolge von Interferenzerscheinungen, geringer war. Antikörperfreie Kinder zeigten im Neutralisationstest eine größere Zuwachsrate an Typ II-und Typ III-Antikörpern als Kinder mit prävaccinalen Antikörpern. Im Endeffekt erreichten aber bei allen drei Typen diejenigen Probanden, die bereits vor der Impfung über Antikörper verfügten, höhere durchschnittliche Titerwerte. Neben dem erwarteten homologen Antikörperzuwachs wurde in 37% der untersuchten Kinder ein Anstieg heterologer neutralisierender Antikörper gegenüber Typ II und in 41% ein solcher gegenüber Typ III festgestellt. Komplementbindende homologe Antikörper waren beim Typ I in 51,8%, beim Typ II in 34,8% und beim Typ III in 21,3% der Fälle nachweisbar. Eine Bildung heterologer komplementbindender Antikörper konnte nur einmal beobachtet werden. Die Ergebnisse wurden insbesondere auch unter dem Blickwinkel des Zeitpunktes der Entnahmen diskutiert.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Informatik-Spektrum 22 (1999), S. 206-209 
    ISSN: 1432-122X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 40 (1953), S. 612-612 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0332-1649
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Ultrasonic motors have attractive properties which compare favourably with electromagnetic motors for certain applications. Their operation is based on piezoelectrically exciting bending waves in the stator and transferring energy to the rotor via friction. Prototypes are typically constructed by trial and error; theoretical studies have proved to be difficult. Describes a two-dimensional model for the stator of a travelling wave ultrasonic motor. The authors have developed a finite element program that is capable of modelling piezoelectric driven systems in the time domain, and their objective is to simulate the excitation of the travelling waves in the stator. They are in fact able to simulate travelling waves. Although the plane strain model cannot account for all excitation modes, they observe the elliptical motion of the material particles on the surface, implying that rotor motion can be mechanically induced.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Archiv der Mathematik 29 (1977), S. 481-484 
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 6 (1988), S. 95-115 
    ISSN: 1573-0662
    Keywords: N2O emission ; forest soils ; field measurements ; seasonal cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract N2O emission rates were measured during a 13-month period from July 1981 till August 1982 with a frequency of once every two weeks at six different forest sites in the vicinity of Mainz, Germany. The sites were selected on the basis of soil types typical for many of the Central European forest ecosystems. The individual N2O emission rates showed a high degree of temporal and spatial variabilities which, however, were not significantly correlated to variabilities in soil moisture content or soil temperatures. However, the N2O emission rates followed a general seasonal trend with relatively high values during spring and fall. These maxima coincided with relatively high soil moisture contents, but may also have been influenced by the leaf fall in autumn. In addition, there was a brief episode of relatively high N2O emission rates immediately after thawing of the winter snow. The individual N2O emission rates measured during the whole season ranged between 1 and 92 μg N2O-N m−2 h−1. The average values were in the range of 3–11 μg N2O-N m−2 h−1 and those with a 50% probability were in the range of 2–8 μg N2O-N m−2 h−1. The total source strength of temperate forest soils for atmospheric N2O may be in the range of 0.7–1.5 Tg N yr−1.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1435-1803
    Keywords: Key words Atherosclerosis – cytokines – endothelins – inflammation – free radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The potent vasoconstrictor peptide endothelin-1 (ET-1) has been implicated in the pathophysiology of atherosclerosis and ist complications. Since inflammation of the vessel wall is a hallmark of atherosclerosis, the purpose of the present study was to investigate the influence of ET-1 on cytokine production in human vascular smooth muscle cells (SMC) as a marker of inflammatory cell activation. ET-1 (100 pM – 1 μM) stimulated interleukin-6 (IL-6) secretion from human vascular SMC in a concentration-dependent manner. The ET-A-receptor antagonist BQ-123 (10 μM), but not the ET-B-receptor antagonist BQ-788, inhibited IL-6 release. ET-1 also transiently increased IL-6 mRNA compatible with regulation of IL-6 release at the pretranslational level. Electrophoretic mobility shift assays demonstrated time-and concentration-dependent activation of the proinflammatory transcription factor nuclear factor-κB (NF-κB) in ET-1-stimulated human vascular SMC. A decoy oligodeoxynucleotide bearing the NF-κB binding site inhibited ET-1-stimulated IL-6 release to a great extent suggesting that this transcription factor plays a key role for cytokine production elicited by ET-1. Moreover, the antioxidant pyrrolidine dithiocarbamate (10 μM) inhibited ET-1-induced IL-6 release indicating involvement of reactive oxygen species in ET-1 signaling. ET-1-stimulated IL-6 secretion was also suppressed by diphenylene iodonium (40 μM), an inhibitor of flavon-containing enzymes such as NADH/NADPH oxidase. The results demonstrate the ability of ET-1 to induce an inflammatory response in human vascular SMC. These observations may contribute to a better understanding of the role of ET-1 in inflammatory activation of the vessel wall during atherogenesis.
    Type of Medium: Electronic Resource
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