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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 62 (1986), S. 250-258 
    ISSN: 1432-1106
    Schlagwort(e): Longterm potentiation ; Hippocampus ; Collateral specificity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Long term potentiation (LTP) in response to brief high frequency trains has been reported for many pathways in the hippocampus. The mechanisms involved are still unclear. The present experiments set out to confirm reports in the literature that LTP of output from CA3 neurons can be specific to particular collaterals. Single pulses delivered to area CA3 produced field responses nearly simultaneously in area CA1 and in the lateral septum (LS). High frequency stimulation of CA3 produced long term potentiation of CA1 but not LS responses. The CA1 response to stimulation of the contralateral hippocampus did not potentiate when the CA1 response to CA3 stimulation showed long term potentiation. The CA1 and LS responses to CA3 stimulation showed similar strength-duration, strength-amplitude and frequency following characteristics. Their latencies were comparable to the latencies of antidromic activation of CA3 cells from CA1 and LS. Movement of stimulating electrodes to the region of the Schaffer collaterals increased the latency of the LS response and decreased the latency of the CA1 response but left the sum of these latencies unchanged. It was concluded that the CA3 and Schaffer stimulation were activating LS and CA1 collaterals of the same CA3 neurons. CA1 and LS responses to CA3 stimulation showed somewhat different paired pulse and frequency potentiation characteristics. These data confirm reports in the literature that long term potentiation is both input-specific and collateral-specific. The mechanisms of long term potentiation are likely, therefore, to be limited to changes at specific synaptic junctions, e.g. changes in sensitivity of specific postsynaptic receptor sites or changes in transmitter release, which can depend on functional or organisational differences between two collaterals of the same neuron.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 54 (1984), S. 567-570 
    ISSN: 1432-1106
    Schlagwort(e): Hippocampus ; Frequency potentiation ; Transmembrane potential ; Ephaptic transmission
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The contribution of ephaptic interactions to potentiation of the hippocampal CA1 extracellular population spike during paired pulse or frequency stimulation of stratum radiatum (SR) inputs was investigated using the in vitro hippocampal slice preparation. Records of the transmembrane potential revealed a depolarizing wave with an amplitude and latency that varied directly with that of the extracellular population spike. Paired pulse or repetitive stimulation of SR resulted in a potentiation of the population spike amplitude and a corresponding increase in the amplitude of the TMP depolarizing wave. Action potentials generated during the stimulus train consistently arose from the peak of the depolarizing wave. It is proposed that ephaptic interactions contribute to potentiation of the extracellular population spike through recruitment of subthreshold neurons within the population during repetitive afferent stimulation.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 56 (1984), S. 243-256 
    ISSN: 1432-1106
    Schlagwort(e): Medial septum ; Hippocampus ; Dentate gyrus ; Evoked potentials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Previous electrophysiological experiments in rabbits have suggested that medial septal stimulation activates dentate granule cells and evokes an associated negative field response at the granule cell layer, without an associated “dendritic” response. Anatomical studies have suggested that septal input to the granule cells may be to stratum moleculare, or close to the cell layer, or may not exist at all. The present experiments confirmed in rats anaesthetised with urethane that medial septal stimulation elicits single action potentials from cells in the granule layer. The associated negative field potential was maximal in the granule cell layer and there was no sign of a separate dendritic potential. The fibres responsible for this potential travel to the dorsal hippocampus in the fornix superior rather than the fimbria, taking the same course as the fibres which contribute to the dense cholinesterase staining just above the granule cell layer. Stimulation at 100 Hz for 1 s of either medial septal, or perforant path, input to the dentate granule cell layer produced long term potentiation of the subsequent evoked field responses to the stimulated pathway. The responses to the non-stimulated pathway were unchanged. Paired pulse stimulation produced both homosynaptic and heterosynaptic potentiation. These data suggest that medial septal input synapses close to granule cell bodies and produces a negative field potential which is a combination of dendritic and population spike potentials. Medial septal input also appeared to produce direct activation of hilar neurones, some of which may be basket cells or other interneurones. The data also show that long term potentiation is specific to this input, perhaps dependent on presynaptic mechanisms. Paired pulse potentiation, at least in the heterosynaptic case appears to depend on postsynaptic mechanisms.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 57 (1985), S. 443-447 
    ISSN: 1432-1106
    Schlagwort(e): Epilepsy ; GABA ; Hippocampus ; Inhibition ; Kindling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In vitro hippocampal slices were prepared from control and commissural-kindled rats and the inhibitory processes of the dentate granule cells were assessed using paired perforant path stimulation. An early (20 ms) Cl--dependent and a late (200 ms-8 s) Cl--independent inhibition were shown to be present in the dentate. Enhancement of the late Cl--insensitive inhibition was observed following the establishment of commissural kindling and persisted for periods of up to eight weeks following the last seizure.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1432-1076
    Schlagwort(e): Complement, neonatal concentrations and activation ; Susceptibility to infection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Determinations of C3, C4, and C5 concentrations by radial immunodiffusion, and assays for the activation products of C3, C3c and C3d by counter-immunoelectrophoresis, were performed on 80 infants. Seven nonbacteremic preterm infants with necrotizing enterocolitis (NEC) or probable NEC (PNEC) were found at the time of diagnosis to have a significantly lower mean concentration of C3 (P〈0.05, 1-tailed) without C3 activation when compared to other noninfected preterm infants. Ten full-term and 63 preterm infants were studied prospectively during the first days of life, and were then followed for the postnatal development of localized or systemic infection. Assays for the detection of C3 activation products were negative in all these infants. Four preterm infants who developed PNEC after 5 or more days without clinical illness had low original concentrations of complement components. The pathogenesis of NEC may not involve primarily complement activation, and susceptibility to this condition may be related to pre-existing deficiencies in complement component concentrations relative to gestational age, or to defective activation of C3 in the presence of certain bacterial species and strains.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 198 (1963), S. 214-215 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Cells of a bakers' yeast isolate (J^493) precultured two days in Wickerham's5 yeast nitrogen base (Difco) with 1 per cent glucose as carbon source were added at a cell density of 4 million per ml. to 180-ml. pharmaceutical bottles containing 8 ml. volumes of liquid and incubated for three days at ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 170 (1952), S. 239-239 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] In the method employed here, phosphorus-32 was added to the nutrient medium in the form potassium dihydrogen phosphate. Aspergillus sp., Hormoden-drum sp. and Penicillium sp. were grown on nutrient agar ('Difco') containing 5 per cent glucose. Saccharomyces cerevisiae was grown in nutrient broth ...
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 197 (1963), S. 722-723 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Culture methods were essentially those of an earlier' investigation5. 100-ml. volumes of pre-sporulation growth medium in 200-ml. round-bottomed flasks were inoculated from 2-day cultures on stock culture medium. The cells from a given pre-sporulation flask were collected by centri -filiation, ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    The @journal of organic chemistry 37 (1972), S. 1478-1485 
    ISSN: 1520-6904
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 252 (1974), S. 234-235 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The work we report here, on the fate of phenol in the rat, necessitates a reappraisal of some hitherto accepted aspects of detoxication. In particular, it focuses attention on the need to re-assess the role of the liver in detoxication. Whole-body autoradiograms1 were prepared using young rats ...
    Materialart: Digitale Medien
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