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  • 1
    Digitale Medien
    Digitale Medien
    Palladium(II) complexes of N2O2 and N2S2 ligands: Syntheses and X-ray crystal structures (1993)
    Springer
    Journal of chemical crystallography 23 (1993), S. 949-953 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract Palladium(II) complexes of an imine-thiophene ligand N,N′ bis(1-methylenethiophene)-1,3-diaminopropane and an amine-phenol ligand N,N′-bis(2-hydroxybenzyl)1,3-diamino-2,2-dimethylpropane were synthesized by reacting K2PdCl4 with alcoholic solutions of the ligands. X-ray structures of the complexes were determined using data from a CAD-4 Nonius diffractometer (MoKα radiation). The structures were solved by conventional methods resulting inR factors of 0.044 and 0.061 using 1841 and 2241 independent reflections, respectively. Crystal data: Complex I, orthorhombic, space groupPbca,a=11.323(2),b=14.819(2),c=23.873(3)Å,V=4006(1)Å3,Z=8. Complex II: Space groupP21/c,a=9.169(2),b=31.920(4),c=8.902(6),β=90.38(2)°,V=2605(1)Å3.Z=4. Both complexes showed coordination of the ligands through the nitrogens only while the sulphur and the oxygen atoms were uncoordinated. Square planar coordination is completed bycis chloro ligands.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01185542
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  • 2
    Digitale Medien
    Digitale Medien
    Dinuclear complex of rhodium(III) with an amine-phenol ligand: synthesis and X-ray crystal structure (1993)
    Springer
    Journal of chemical crystallography 23 (1993), S. 719-723 
    Details
    ISSN: 1572-8854
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Physik
    Notizen: Abstract A new rhodium(III) complex of an amine-phenol ligand N,NN′-bis-(2-hydroxybenzyl)1,3-diaminopropane was synthesized and characterized by X-ray diffraction studies. Diffraction data were collected by theθ-2θ scan method using MoKα. radiation. The structure was solved by conventional methods resulting in a final R factor of 0.037 for 1954 independent reflections (F o 〉2σ(F o )). The structure consists of a dinuclear complex with two μ-hydroxy bridges between the two Rh atoms. The overall charge of the molecule is neutral due to deprotonation of all phenolic groups. Crystal data: triclinic, space groupP¯1,a=7.308(3)Å;b=9.586(3)Å,c=12.686(5)Å, α=87.51(2), β=88.28(2), γ=71.70(3)°,V=866.6(6)Å3;Z=2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01187273
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  • 3
    Digitale Medien
    Digitale Medien
    Structure of ferrichrome-type siderophores with dissimilarN δ-acyl groups: Asperchrome B1,B2,3,D1, D2 and D3 (1988)
    Springer
    BioMetals 1 (1988), S. 77-89 
    Details
    ISSN: 1572-8773
    Schlagwort(e): Siderophore ; Asperchrome ; Structure determination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary Asperchromes are a series of iron-chelating compounds which contain a cyclic hexapeptide backbone as in ferrichrome siderophores and differ from the latter in having heterogenous acyl groups in the ornithine side chains. The molecular structures of the asperchrome B and D series have been determined by1H- and13C-NMR spectroscopy; single-crystal X-ray diffraction was used to determine the detailed structural features of asperchrome B1 and asperchrome D1. Asperchrome B1 crystallizes in the triclinic space group P1 witha= 1.3143(5) nm,b=1.2200(5) nm,c=0.8949(3) nm,α=105.17(4)°,β=94.03(3)°, γ=109.65(3)°,V=1.2843 nm3,Z=1, ρ x =1.446 g cm−3. FinalR=0.054 for 4625 reflections measured at 138 K using MoKα. Asperchrome D1 crystallizes in the monoclinic space group P21 witha=1.2248(11) nm,b=1.3795(9) nm,c=1.3644(6) nm,β=93.24(6)°,V=2.3016 nm3,Z=2, ρ x =1.418 g cm−3. FinalR=0.110 for 3180 reflections measured at 138 K using MoKα radiation. The conformation of the molecular backbone and iron coordination geometry in both asperchrome B1 and D1 compare well with those observed in other known ferrichrome siderophores. The differences in the acyl groups are illustrated and the structural results are correlated with their iron transport properties.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01138065
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  • 4
    Digitale Medien
    Digitale Medien
    Exposure of non-applicator personnel and adjacent areas to aerially applied propanil (1987)
    Springer
    Bulletin of environmental contamination and toxicology 39 (1987), S. 126-133 
    Details
    ISSN: 1432-0800
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik , Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01691800
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  • 5
    Digitale Medien
    Digitale Medien
    A simple rocker for organ culture (1983)
    Springer
    Methods in cell science 8 (1983), S. 69-71 
    Details
    ISSN: 1573-0603
    Schlagwort(e): rocker platform ; organ culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A simple, reliable, and economical rocker platform is described for use with organ cultures requiring slow, gentle oscillations in a CO2 incubator. The basic elements are a vailable in any research machine shop and the simple economical synchronous motor is available in Ac and Dc, 220 and 110 V.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02099241
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  • 6
    Digitale Medien
    Digitale Medien
    The contributions of position, direction, and velocity to single unit activity in the hippocampus of freely-moving rats (1984)
    Springer
    Experimental brain research 54 (1984), S. 195-195 
    Details
    ISSN: 1432-1106
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00235832
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  • 7
    Digitale Medien
    Digitale Medien
    The contributions of position, direction, and velocity to single unit activity in the hippocampus of freely-moving rats (1983)
    Springer
    Experimental brain research 52 (1983), S. 41-49 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Neurophysiology ; Single units ; Hippocampus ; Radial maze behavior ; Cognitive maps ; Place cells
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Isolated single units in rat dorsal hippocampus and fascia dentata were classified as ‘Theta’ or ‘Complex-Spike’ cells, and their firing characteristics were examined with respect to position, direction and velocity of movement during forced choice, food rewarded search behavior on a radial eight arm maze. Most spikes from CS cells ocurred when the animal was located within a particular place on the maze and moving in a particular direction. Theta cells had very low spatial selectivity. Both cell categories had discharge probabilities which increased somewhat as a function of running velocity but tended to asymptote well before half-maximal velocity. The place/direction specificity of CS cells was significantly higher in CA1 than in CA3 and CA3 CS cells exhibited a striking preference for the inward radial direction. The pronounced directional selectivity of CS cells, at least in the present environment, suggests that they fire in response to complex, but specific, stimulus features in the extramaze world rather than to absolute place in a non-egocentric space. An alternative possibility is that the geometrical constraints of the maze surface have a profound influence on the shapes of the response fields of CS cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00237147
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  • 8
    Digitale Medien
    Digitale Medien
    Hippocampal granule cells are necessary for normal spatial learning but not for spatially-selective pyramidal cell discharge (1989)
    Springer
    Experimental brain research 76 (1989), S. 485-496 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Hippocampus ; Single units ; Place cells ; Colchicine ; Spatial behavior
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The effects of massive destruction of granule cells of the fascia dentata on the spatial and temporal firing characteristics of pyramidal cells in the CA1 and CA3 subfields of the hippocampus were examined in freely moving rats. Microinjections of the neurotoxin colchicine were made at a number of levels along the septo-temporal axis of the dentate gyri of both hemispheres, resulting in destruction of over 75% of the granule cells. By contrast there was relatively little damage to the pyramidal cell fields. As assessed by three different behavioral tests, the colchicine treatment resulted in severe spatial learning deficits. Single units were recorded from the CA1 and CA3 subfields using the stereotrode recording method while the animals performed a forced choice behavioral task on the radial 8-arm maze. Considering the extent of damage to the dentate gyrus, which has hitherto been considered to be the main source of afferent information to the CA fields, there was remarkably little effect on the spatial selectivity of “place cell” discharge on the maze, as compared to recordings from control animals. There was, however, a change in the temporal firing characteristics of these cells, which was manifested primarily as an increase in the likelihood of burst discharge. The main conclusion derived from these findings is that most of the spatial information exhibited by hippocampal pyramidal cells is likely to be transmitted from the cortex by routes other than the traditional “trisynaptic circuit”. These routes may include the direct projections from entorhinal layers II and III to CA3 and CA1, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00248904
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  • 9
    Digitale Medien
    Digitale Medien
    Behavioral correlates of theta-on and theta-off cells recorded from hippocampal formation of mature young and aged rats (1990)
    Springer
    Experimental brain research 80 (1990), S. 365-373 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Hippocampus ; Theta cells ; Place fields ; Movement correlates ; Spatial performance ; Rats
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Most hippocampal formation single units in freely behaving rats fall into one of two categories (Ranck 1973). The most obvious behavioral correlate of complex-spike (CS) cells is spatially selective discharge (O'Keefe and Dostrovsky 1971), while theta cells show increased firing in phase with the EEG θ rhythm associated with Vanderwolf's Type I behaviors (e.g. walking, exploration). Recently, Colom and Bland (1987) described, in urethane anesthetized animals, a class of non-CS cell which was inactive in the presence of EEG θ and discharged continuously during LIA. They called these “theta-off” cells and used the term “theta-on” to refer to the classical “theta” cell. We describe the behavioral correlates of 14 theta-off cells encountered in CA1 (n = 1), hilus fascia dentata (FD; n = 4), subiculum (n = 6), and entorhinal cortex (n = 3). These cells were encountered very infrequently in the course of several experimental investigations of mature young and old rats involving 885 hippocampal neurons recorded from 33 rats during radial maze performance. Fourteen theta-on cells encountered within a few hundred microns of the sites where theta-off cells were recorded were included for comparison. Both theta-on and theta-off cells discharged single spikes and did not show CS bursting characteristic of pyramidal cells. Theta-off cells, however, exhibited significantly greater spike durations than theta-on cells. Mean rates for theta-on and theta-off cells were 8.7 Hz and 6.5 Hz, respectively. Maximum rates were 114 Hz and 104 Hz, respectively. Some cells of both types showed 6–8 Hz modulation while animals traversed the maze. Whereas firing rate for theta-on cells increased smoothly with running velocity, it decreased smoothly for theta-off cells. While no theta-on cells exhibited clear spatial selectivity, two hilar theta-off cells did. When EEG θ rhythm was temporarily abolished by local injection of tetracaine into the medial septum, two theta-off cells were observed to fire continuously at high rates irrespective of behavior, with a pronounced 18–20 Hz rhythmic modulation. Under these circumstances, theta-on cells decrease their rates. Within the 7 theta-off cells recorded in each of the two age groups, there were no statistically significant differences in firing characteristics. Possible anatomical candidates for theta-off cells are considered.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00228163
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  • 10
    Digitale Medien
    Digitale Medien
    Behavioral state dependence of homo- and hetero-synaptic modulation of dentate gyrus excitability (1993)
    Springer
    Experimental brain research 93 (1993), S. 55-65 
    Details
    ISSN: 1432-1106
    Schlagwort(e): Inhibition ; Dentate gyrus ; Hippocampus ; Behavioral state ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of two different waking behavioral states on the modulation of perforant, path-evoked population spikes were studied following prestimulation of either the perforant path itself, the dentate gyrus commissural/association pathway, or the medial septum. The intermediate-latency, post-inhibitory ‘rebound’ of the population spike, which normally follows short-latency, perforant path or commissure-induced inhibition, was substantially increased during forced locomotion on a treadmill, compared with quiet wakefulness. There was no effect of these behavioral states either on the short-latency inhibitory phase itself or on the average magnitude of the unconditioned population spike. The short-latency, GABA-mediated disinhibitory effect of medial septal prestimulation was slightly reduced by walking, as might be expected from the increased feedforward excitatory drive on hippocampal interneurons that occurs during walking. Septal prestimulation during walking also led to a large, intermediate-latency spike facilitation that was completely absent during the quiet, awake state. Lesions of the medial septum attenuated the effects of behavioral state on the post-inhibitory facilitation from both perforant path and commissural stimulation. Atropine reduced the walking-induced increase in intermediate-latency facilitation, but had no effect in the still condition. We conclude that, during walking, electrical stimulation within the hippocampal formation or septum leads to a delayed increase in dentate gyrus excitability that is probably mediated polysynaptically through the medial septum or fibers passing through it. This state dependency is not due to tonic suppression of the inhibitory systems within the dentate gyrus itself.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00227780
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