Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (14)
  • 1985  (14)
Source
Material
Years
  • 1985-1989  (14)
Year
Keywords
  • 11
    Electronic Resource
    Electronic Resource
    Compensation in the number of presynaptic dense projections and synaptic vesicles in remaining parallel fibres following cerebellar lesions (1985)
    Springer
    Journal of neurocytology 14 (1985), S. 673-687 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Our previous investigations demonstrated an increase in the size of remaining synaptic sites as an intermediate or possible alternative to sprouting plasticity. The total amount of postsynaptic contact area remained relatively constant for each target neuron even though there was a marked decrease in the number of sites on these neurons. In addition, enlarged boutons containing numerous synaptic vesicles were positioned adjacent to enlarged postsynaptic sites. The question posed by this study was to determine whether dense projections, parts of the presynaptic grids of the remaining parallel fibres, spread to cover the enlarged postsynaptic sites, or if the number of these densities increased on each site to maintain the structural organization of the presynaptic grid. In addition, the number of synaptic vesicles per bouton was quantitated to determine whether they compensated by increasing their number in relationship to the increased area of the presynaptic grid. The number of parallel fibre synapses on Purkinje cells was reduced by transection of a narrow bundle of parallel fibres accompanied by a small lesion undercutting the molecular layer to destroy granule cells contributing to this bundle. The number of presynaptic dense projections was quantitated in control and lesioned preparations (using ethanolic phosphotungstic acid staining) in order to determine their correlation to the area of each site. In addition, the average number of synaptic vesicles in boutons was compared to the average size of boutons and the average contact area of the synaptic sites. At 3 to 7 days following partial deafferentation of Purkinje cells in adult rats, the density of dense projections of parallel fibre synapses on Purkinje cell spines remained uniform. This occurred throughout a range of reduction in the number of synapses in conjunction with a reciprocal increase in the size of sites. The finding of a uniform density of these projections and an increase in the size of sites implies that each granule cell axon must gain dense projections. In addition, the remaining presynaptic boutons had a uniform density of synaptic vesicles even though the volume of the boutons and the area of the synaptic contact doubled. Thus, the number of synaptic vesicles gained in proportion to the total enlargement of the contact site and the bouton size. These results strongly suggest that deficits or losses in synaptic connections of parallel fibre on Purkinje cell spines produces a compensation in the total number of synaptic vesicles and presynaptic dense projections of the remaining boutons. An enlargement of the presynaptic grid occurs in concert with redistribution of the constant total area of membrane occupied by macromolecules (or insertion of new ones) on remaining postsynaptic sites. These compensations could be facilitating efficacy of neuronal connections after lesions or neuronal attrition by re-establishing available transmitter and release sites in proportion to the constant amount of receptor area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01200804
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Diffusion and solubility of some azo dyes in swollen gelatin matrices: The effects of dye size, matrix swell, and dye-matrix interactions (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 2075-2094 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The diffusion coefficient (D) and the solubility coefficient (K) of three sulfonated azo dyes were measured in swollen gelatin membranes at pH 12 by two techniques (time lag and desorption rate), with good agreement between the two. A strong correlation was established between log D and the reciprocal of the free volume of the matrix. Hence, as free volume of the matrix increased (due to increasing solvent imbibition), dye mobility increased. As dye size increased, however, mobility decreased. Dye affinity for gelatin, as measured in dilute solutions by dynamic dialysis, was small and could be related to the dye solubility in more concentrated gelatin matrices. Increasing ionic strength or decreasing alcohol content increased K without affecting the dye mobility. On the other hand, the presence of polymers with strong affinity for the dye anions, e.g., polyvinylpyrrolidone, immobilized a large fraction of the dye ions and greatly slowed the overall dye transport.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1985.070300524
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Tracer diffusion of aromatic hydrocarbons in liquid cyclohexane up to its critical temperature (1985)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 31 (1985), S. 1510-1515 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Tracer diffusion coefficients in liquid cyclohexane of benzene, toluene, p-xylene, mesitylene, naphthalene, and phenanthrene have been determined from 298.2 to 523.2 K (TR = 0.54 ∼ 0.95) using the Taylor dispersion method. Positive deviations from the Arrhenius relationship are observed as the critical temperature is approached, but a rough-hard-sphere theory is found to be adequate for describing the data across the entire temperature range. On the basis of the computer simulation results for hard-sphere fluids, correlations involving solute and solvent critical volumes and their molecular weights have also been developed for practical applications. Tracer diffusivities in supercritical carbon dioxide are also adequately represented by the proposed correlation, as the fluid density is not far removed from that of liquid carbon dioxide.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690310914
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Translational diffusion of polystyrene in cyclohexane at infinite dilution from 283 to 348 K (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2457-2468 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The translational diffusion coefficients are reported for polystyrenes with molecular weights 2000, 4000, and 9000 in cyclohexane at infinite dilution from 283.2 to 348.2 K. The results suggest that the hydrodynamic radii stay constant to within ±3% and that the real chain for molecular weight 9000 at 308.2 K is well represented by a Gaussian or Monte Carlo model involving the idea of statistical steps. Furthermore, the success of Hildebrand's free-volume empiricism has led to a correlation between Dμ0/T and M which represents the observed diffusivities to within ±2%.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180231204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...