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  • 1
    Electronic Resource
    Electronic Resource
    RGM is a repulsive guidance molecule for retinal axons (2002)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 419 (2002), S. 392-395 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Axons rely on guidance cues to reach remote targets during nervous system development. A well-studied model system for axon guidance is the retinotectal projection. The retina can be divided into halves; the nasal half, next to the nose, and the temporal half. A subset of retinal axons, those ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01041
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  • 2
    Electronic Resource
    Electronic Resource
    Eph receptor–ligand interactions are necessary for guidance of retinal ganglion cell axons in vitro (1998)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 10 (1998), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Previous results of an in vitro guidance test, the stripe assay, have demonstrated the presence of a repulsive axon guidance activity for temporal retinal axons in the posterior part of the vertebrate optic tectum. Ephrin-A5 and Ephrin-A2 are ligands for the EphA subfamily of Eph receptor tyrosine kinases, which are expressed in overlapping gradients in the posterior part of the tectum. When recombinantly expressed, both proteins have been shown to guide retinal ganglion cell axons in the stripe assay. While these results suggest that Ephrin-A5 and Ephrin-A2 form part of the posterior repulsive guidance activity, they do not elucidate whether they are necessary components. Here we report that soluble forms of the ligands at nanomolar concentrations completely abolish this repulsive activity. Similar results were obtained with the soluble extracellular domain of EphA3, which is a receptor for Ephrin-A2 and Ephrin-A5, but not with the corresponding domain of EphB3, a receptor for the transmembrane class of Eph ligands. These experiments show that the repulsive axon guidance activity seen in the stripe assay is mediated by Ephrin-A ligands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.1998.00180.x
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  • 3
    Electronic Resource
    Electronic Resource
    Spinal cord injury-induced lesional expression of the repulsive guidance molecule (RGM) (2005)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 21 (2005), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The repulsive guidance molecule (RGM) is involved in the formation of the central nervous system (CNS) during development by modulating guidance of growing axons. However, a role of RGM in CNS injury remains to be established. We studied the expression of RGM in the spinal cord of rats with spinal cord injury (SCI). After SCI, RGM+ cells accumulated in lesions and peri-lesional areas. During the first days after SCI, RGM expression was confined to neurons, ballooned neurite fibers/retraction bulbs, smooth muscle/endothelial cells, and to leucocytes infiltrating the lesion. Lesional RGM expression was frequently confined to hypertrophic β-APP+ and RhoA+ neurites/retraction bulbs. With maturation of the lesion, we observed RGM expression by components of the developing scar tissue (cicatrix), such as fibroblastoid cells, reactive astrocytes and in addition a pronounced extracellular RGM deposition resembling neo-laminae. Frequent RGM+, RhoA+ coexpression by lesional retraction bulbs represent first preliminary evidence of RGM to exert growth inhibitory effects by the second messenger system RhoA. To date, RGM is one of the most potent axonal growth inhibitors identified and present in axonal growth impediments (i) oligodendrocytes; (ii) the plexus choroideus and (iii) components of the developing scar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2005.03962.x
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  • 4
    Electronic Resource
    Electronic Resource
    GROWTH CONE GUIDANCE: First Steps Towards a Deeper Understanding (1999)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 22 (1999), S. 351-388 
    Details
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Growth cones, the hand-like structures at the tip of growing neurites, possess remarkable abilities to detect directional cues. On their way to their targets they traverse a dense jungle of many different cells, expressing a variety of different molecular guidance cues. Proper reading and integration of these cues is essential for precise wiring of different parts of the peripheral and central nervous systems. Guidance cues have been classified according to the response they elicit as either attractive or repulsive. Recent work, however, suggests that this might not represent an absolute distinction and that the internal state of the growth cone can dictate whether it detects a cue as repulsive or attractive. This article reviews some new experimental approaches to understanding growth cone signal transduction mechanisms induced by extracellular guidance cues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.neuro.22.1.351
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  • 5
    Electronic Resource
    Electronic Resource
    Early Cambrian oceanic plagiogranite in the Silvretta Nappe, eastern Alps: geochemical, zircon U-Pb and Rb-Sr data from garnet-hornblende-plagioclase gneisses (1996)
    Springer
    International journal of earth sciences 85 (1996), S. 822-831 
    Details
    ISSN: 1437-3262
    Keywords: Austro-Alpine ; Eastern Alps ; Oceanic rocks ; Rb-Sr ; Zircon ; U-Pb ; Magmatism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Garnet-hornblende-plagioclase gneisses rich in incompatible elements occur in the crystalline basement of the Austro-Alpine Silvretta nappe and are associated with clinopyroxene norites and harzburgite cumulates. It is proposed here that the gneisses were formerly oceanic plagiogranites. An εNd(530) value of +5.6 for the gneisses as well as initial87Sr/86Sr values of 0.7036–0.7037 for the gabbroic rocks and 0.7026–0.7027 for the ultramafic rocks suggest a mantle source for this rock association. The geochemical characteristics of the garnet-hornblende-plagioclase gneisses indicate that their precursors were derived by fractional crystallization from a basaltic parent magma, by the same process which produced the adjacent clinopyroxene norites and ultramafic cumulates as well. The combined U-Pb upper intercept ages of zircons from two gneiss samples yield an igneous crystallization age of 532 ± 30 Ma, similar to previously dated (mostly calcalkaline) orthogneisses in the same area. High-quality transparent zircons showed the least degree of discordance, but contain extremely low U and Pb levels. The rock suite, including this plagiogranite, was emplaced within oceanic crust which formed in the latest Precambrian-early Palaeozoic off the northern continental margin of Gondwana.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02440113
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  • 6
    Electronic Resource
    Electronic Resource
    U-Pb and Pb-Pb zircon dating of the older orthogneiss suite in the Silvretta nappe, eastern Alps: Cadomian magmatism in the upper Austro-Alpine realm (1995)
    Springer
    International journal of earth sciences 84 (1995), S. 457-465 
    Details
    ISSN: 1437-3262
    Keywords: Eastern Alps ; Magmatism ; Alkaline rocks ; Geochronology ; U-Pb ; Zircon ; Cadomian Pan-African
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Two orthogneiss suites dominate the Silvretta nappe. Primary crystallization of the larger suite (‘younger orthogneisses’) is assumed to be Ordovician in age. The second, adjacent magmatic suite consists of older, alkaline to calc-alkaline, ultrabasic, basic to intermediate and granitic rocks known as ‘older orthogneisses’. U-Pb data of multigrain zircon fractions, as well as single zircon stepwise evaporation 207Pb/206Pb results suggest a latest Proterozoic to early Cambrian intrusion age for the protoliths of the ‘older orthogneisses’ as both dating methods yield early Cambrian crystallization ages of 526±7 and 519±7 Ma for an alkaline granite gneiss; similar results were obtained for two neighbouring calc-alkaline orthogneisses (207Pb/206Pb ages of 533 ± 4 and 568 ± 6 Ma, respectively). The crystal habitus corresponds to P5, S19 and S9 zircons of magmatic origin. Whole-rock initial Sr isotope ratios indicate a primitive source. The igneous protoliths of these ‘older orthogneisses’ represent a fragment of a Cadomian (Pan-African) crust found in places within the basement of the European Hercynides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00284513
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  • 7
    Electronic Resource
    Electronic Resource
    Albumin Nanospheres as Carriers for Passive Drug Targeting: An Optimized Manufacturing Technique (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 32-37 
    Details
    ISSN: 1573-904X
    Keywords: albumin ; nanospheres ; manufacturing ; glutaraldehyde ; cross-linking ; central composite design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purpose of this study was to develop a new method to produce albumin particles in the sub-200-nanometer range with a narrow size distribution and in a controlled and reproducible manner. Methods. A new emulsion crosslinking method was developed using ultrasound and static mixing as homogenization steps and a central composite design was used to evaluate the influence of different process parameters on particle size, polydispersity and yield. Results. Response surface analysis allowed the location of the most important factors. Of all the factors investigated, only the albumin concentration and the aqueous phase volume showed a significant influence on response parameters. Albumin nanospheres with sizes below 200 nm in diameter and very narrow size distributions were obtained in high yields (〉80%). Conclusions. This study describes a new preparation method for albumin nanoparticles which are suitable for future drug targeting studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016064930502
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  • 8
    Electronic Resource
    Electronic Resource
    Multiple Endotheliome der Blutkapillaren (1912)
    Springer
    Virchows Archiv 209 (1912), S. 352-367 
    Details
    ISSN: 1432-2307
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01947930
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  • 9
    Electronic Resource
    Electronic Resource
    Low-Mach-Number Asymptotics of the Navier-Stokes Equations (1998)
    Springer
    Journal of engineering mathematics 34 (1998), S. 97-109 
    Details
    ISSN: 1573-2703
    Keywords: Navier-Stokes equations ; low-Mach-number limit ; multiple scales ; asymptotics.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Technology
    Notes: Abstract A multiple-time scale, single-space scale asymptotic analysis of the compressible Navier-Stokes equations reveals how the heat-release rate and heat conduction affect the zeroth-order global thermodynamic pressure, the divergence of velocity and the material change of density at low-Mach-numbers. The asymptotic analysis identifies the acoustic time change of the heat-release rate as the dominant source of sound in low-Mach-number flow. The viscous and buoyancy forces enter the computation of the second-order ‘incompressible’ pressure in low-Mach-number flow in a similar way as they enter the pressure computation in incompressible flow, except for a nonzero velocity-divergence constraint. If the flow equations are averaged over an acoustic wave period, the averaged velocity tensor describes the net acoustic effect on the averaged flow field. Removing acoustics from the equations altogether leads to the low-Mach-number equations, which allow for large temperature and density changes as opposed to the Boussinesq equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004349817404
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  • 10
    Electronic Resource
    Electronic Resource
    Early Cambrian oceanic plagiogranite in the Silvretta Nappe, eastern Alps: geochemical, zircon U–Pb and Rb–Sr data from garnet–hornblende–plagioclase gneisses (1996)
    Springer
    Geologische Rundschau 85 (1996), S. 822-831 
    Details
    ISSN: 0016-7835
    Keywords: Key words Austro-Alpine ; Eastern Alps ; Oceanic rocks ; Rb ; Sr ; Zircon ; U ; Pb ; Magmatism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Garnet–hornblende–plagioclase gneisses rich in incompatible elements occur in the crystalline basement of the Austro-Alpine Silvretta nappe and are associated with clinopyroxene norites and harzburgite cumulates. It is proposed here that the gneisses were formerly oceanic plagiogranites. An εNd( 530 ) value of +5.6 for the gneisses as well as initial 87Sr/86Sr values of 0.7036–0.7037 for the gabbroic rocks and 0.7026–0.7027 for the ultramafic rocks suggest a mantle source for this rock association. The geochemical characteristics of the garnet–hornblende–plagioclase gneisses indicate that their precursors were derived by fractional crystallization from a basaltic parent magma, by the same process which produced the adjacent clinopyroxene norites and ultramafic cumulates as well. The combined U–Pb upper intercept ages of zircons from two gneiss samples yield an igneous crystallization age of 532±30 Ma, similar to previously dated (mostly calc-alkaline) orthogneisses in the same area. High-quality transparent zircons showed the least degree of discordance, but contain extremely low U and Pb levels. The rock suite, including this plagiogranite, was emplaced within oceanic crust which formed in the latest Precambrian–early Palaeozoic off the northern continental margin of Gondwana.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050114
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