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  • 1990-1994  (4)
  • Chemistry  (2)
  • ACTH  (1)
  • Afterhyperpolarization  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 99 (1994), S. 214-222 
    ISSN: 1432-1106
    Keywords: Afterhyperpolarization ; Motoneuron ; Locomotion ; In vitro ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Motoneuron afterhyperpolarization (AHP) amplitude and somatic input conductance were monitored during pharmacologically induced, locomotorlike ventral root activity using an isolated neonatal rat spinal cord preparation (transected at the C1 level). Nonspontaneously firing motoneurons were selected for study. Single spikes were evoked at regular intervals by brief depolarizing current pulse injections, while somatic input conductance was monitored by hyperpolarizing current pulses. The induction of rhythmic ventral root activity was associated with tonic depolarization of motoneurons as well as superimposed rhythmically alternating membrane depolarization and hyperpolarization (locomotor drive potentials, LDPs). In 9 of 13 trials (six of eight cells) the peak amplitude of AHPs following current-evoked action potentials was reduced during both the hyperpolarized and the depolarized phases of the LDP, compared with the pre-locomotor condition. The peak AHP amplitude increased during the depolarized phase of the LDP in 4 of 13 trials (three of eight cells); however, in 3 of these 4 trials measurement of the AHP later in the course of its trajectory, using a half decay time (HDt) reference point, demonstrated AHP amplitude reduction during rhythmic activity compared with the prelocomotor condition. In seven of eight motoneurons the induction of rhythmic activity was associated with a decrease in input conductance. The pattern of AHP amplitude and conductance modulation during the two phases of the LDP was consistent for individual trials; however, there was considerable intertrial variation. The results suggest that AHP modulation during locomotor-like activity in this preparation can be mediated independently of supraspinal influences by intrinsic spinal cord mechanisms, and the observed AHP suppression does not appear to be the passive result of an increase in background conductance. The discrepancy between peak and HDt-based AHP amplitude measurements during the depolarized phase of the LDP in some trials may be due to competing effects of passively enhanced potassium currents and a mechanism that actively reduces the calcium-dependent potassium conductance. The possibility that both the AHP amplitude and the input conductance changes observed during locomotor-like activity reflect a regulation of potassium channels is discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1041
    Keywords: Ipsapirone ; CRF ; ACTH ; cortisol ; time series analysis ; hypothalamic-pituitary-adrenal axis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The neuroendocrine effects (changes in plasma CRF, ACTH and cortisol) of single and multiple (t.d.s. for 2 days) doses of ipsapirone (BAY Q 7821) 5 and 10 mg have been investigated in 6 healthy male volunteers. The study followed a balanced complete block, placebo-controlled and double blind design with two baseline phases (pre and post-treatment). Volunteers were investigated on identical days during 5 successive weeks. The results do not show a specific effect of ipsapirone on the hypothalamic-pituitary-adrenal axis when doses in the range of 5–30 mg per day were given.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 43 (1992), S. 151-158 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Measurement methods that are applicable for the characterization of porous structures, i.e. differential scanning calorimetry, low-temperature gas adsorption, mercury high pressure porosimetry, electron and light microscopy, X-ray small angle scattering, water retention value, and apparent density, are described with respect of the peculiarities of poly(acrylonitrile) fibres. The methods have been applied on differently stretched and thermally treated PAN fibres in the gel state and after dehydration, respectively. The observed effects are explained by the different stabilities of the gel fibre structure.
    Notes: Die zur Charakterisierung von Porenstrukturen anwendbaren Meßmethoden Differential-Scanning-Calorimetrie, Tieftemperatur-Gasadsorption, Quecksilber-Hochdruckporosimetrie, Elektronen- und Lichtmikroskopie, Röntgenkleinwinkelstreuung sowie Wasserrückhaltevermögen und scheinbare Dichte werden unter Berücksichtigung der Besonderheiten von Polyacrylnitrilfasern vorgestellt. Die genannten Methoden wurden auf unterschiedlich gereckte und thermisch behandelte PAN-Fasern im Gelzustand und nach Entwässerung angewendet. Die dabei auftretenden Effekte werden mit der unterschiedlichen Stabilität der Gelfaserstruktur erklärt.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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