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  • 1
    Electronic Resource
    Electronic Resource
    Binocular depth perception mechanisms in tongue-projecting salamanders (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 365-377 
    Details
    ISSN: 1432-1351
    Keywords: Salamander ; Depth perception ; Stereopsis Optic tectum ; Visual maps
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Tongue-projecting salamanders (Bolitoglossini) combine extreme speed and high precision in prey capture. They possess all requirements for stereoscopic depth perception: frontally oriented eyes, a substantial amount of direct ipsilateral projection in addition to the contralateral one, and binocularly driven neurons. Extracellular recordings were made from retinal afferents in the tectum as well as from the somata of tectal neurons. RF-sizes of afferents and tectal neurons were determined, and the response properties of tectal neurons were tested under monocular and binocular conditions with stimuli of different size and velocity. While RF-sizes and response properties of binocular neurons during binocular and contralateral stimulation were similar, ipsilaterally stimulated neurons exhibited much smaller RFs, lower spike rates and different size preferences. Furthermore, the contralateral retinotectal projection from one eye and the ipsilateral from the other are in register. While retinal afferents are distributed linearly over the tectal surface, most tectal neurons are activated by a retinal area corresponding to the frontal visual field; this results in a magnification of this region. The two monocular receptive fields of binocular neurons exhibit zero disparities (horopter) at distances that coincide with the maximum reach of the tongue. We hypothesize that bolitoglossine salamanders (as well as amphibians in general) make use of two kinds of disparities: (1) between the maps in the left and right tectal hemisphere, coding for the lateral eccentricity of an object, and (2) between the ipsilateral and contralateral retinotectal map, coding for the distance. The presence of substantial direct ipsilateral afferents in bolitoglossine salamanders appears to be the basis for a fast computation of object distance, which is characteristic of these animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219062
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  • 2
    Electronic Resource
    Electronic Resource
    Simulander: A neural network model for the orientation movement of salamanders (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 379-389 
    Details
    ISSN: 1432-1351
    Keywords: Neural network ; Evolution strategy ; Salamander ; Optic tectum ; Orienting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Simulander is a feedforward neural network simulating the orientation movement of salamanders. The orientation movement is part of the prey capture behavior; it is performed with the head alone. Simulander is a network which consists of 300 neurons incorporating several cytoarchitectonic and electrophysiological features of the salamander brain. The network is trained by means of an evolution strategy. Although only 100 tectum neurons with fairly large receptive fields are used (“coarse coding”), Simulander is able to localize an irregularly moving prey precisely. It is demonstrated that large receptive field neurons are important for successful prey localization. The removal of a model tectum hemisphere leads to a network which accounts for investigations made in living monocular salamanders. The model also yields an understanding of electrical stimulation experiments in toads.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219063
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Simultaneous gas chromatographic determination of methanol and free glycerol in biodiesel (1996)
    Springer
    Chromatographia 42 (1996), S. 431-434 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fatty acid methyl esters ; Biodiesel ; Methanol ; Glycerol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The methanol and free glycerol content of vegetable oil methyl esters used as diesel fuel (biodiesel) is very important in describing the quality of this fuel and is therefore limited by specifications. A previously described GLC method for the determination of free glycerol in biodiesel has been further developed and also allows the simultaneous determination of methanol. Sample preparation includes dissolving in dimethylformamide, silylation with bis-trimethylsilyltrifluoracetamide (BSTFA) and separation on a methylsilicone fluid, coated-capillary column using either FID or MS-detection. Ethanol and 1,4-butanediol were used as internal standards. Both detection systems show sufficient sensitivity for concentrations relevant to biodiesel samples. The recovery was tested using a RME-sample containing known amounts of methanol and glycerol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272135
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  • 4
    Electronic Resource
    Electronic Resource
    MTS1 expression and prognosis in acute myeloid leukemia (1997)
    Springer
    Annals of hematology 75 (1997), S. 141-144 
    Details
    ISSN: 1432-0584
    Keywords: Key words MTS1 ; p16 ; Tumor suppressor gene ; Leukemia ; Prognostic factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  MTS1, a tumor supressor gene located on chromosome 9p21, has been shown to be altered in a number of human tumor cell lines, primary solid tumors, and leukemias. In this study we found low expression of MTS1 in lymphocytes from seven of nine healthy donors, but in none of eight granulocyte samples from the same controls, suggesting a physiological role of MTS1 in peripheral blood cells capable of proliferation, but not in end-stage differentiated cells. We detected MTS1 mRNA expression in 38 of 57 patients (66%) with acute myelogenous leukemia (AML) treated in a standardized clinical protocol. No deletion of the MTS1 gene was found in any of the AML samples tested. There was no significant association between expression of MTS1 and response to therapy, progression-free, or overall survival. Except for a negative correlation between MTS1 level and leukocyte count at diagnosis (p=0.03), there was also no association with any of the known prognostic parameters in AML. We conclude that MTS1 shows a significantly higher expression in leukemic than in normal peripheral blood cells, that deletion of MTS1 is not a frequent event in AML, and that its expression is not significantly correlated with outcome of the disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770050331
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  • 5
    Electronic Resource
    Electronic Resource
    The role of peroxisomes in aging (1998)
    Springer
    Cellular and molecular life sciences 54 (1998), S. 641-652 
    Details
    ISSN: 1420-9071
    Keywords: Key words. Peroxisome; aging; lipid metabolism; oxidative stress.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Reactive oxygen species and alterations in membrane lipid homeostasis are thought to be important events in aging process and aging-related degenerative diseases. The peroxisome is a small cellular organelle involved in both oxygen and lipid metabolism, and defects in peroxisomal function are associated with major, and often fatal, changes at the neurological level during human development. Recent reports of aging-related changes in peroxisomal function raised the hypothesis that peroxisomes may also have a significant role in the aging process and aging-related degenerative diseases. This review presents the current data on changes in peroxisomal function during aging and discusses the implications of these changes for health.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000180050192
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    A high-yielding serum-free, suspension cell culture process to manufacture recombinant adenoviral vectors for gene therapy (1998)
    Springer
    Cytotechnology 28 (1998), S. 81-89 
    Details
    ISSN: 1573-0778
    Keywords: adenovirus ; HEK 293 ; perfusion ; serum free media ; suspension perfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract We have developed an efficient, reproducible, and scaleable cell culture process for a recombinant adenoviral vector expressing therapeutic transgenes for clinical trials. HEK 293 cells – which support the propagation of E1 deficient adenovirus – were first adapted to serum free media and suspension growth. Subsequent studies focused on the infection, virus production and harvest from suspension culture bioreactors. Future studies are planned to address the kinetics of adenovirus production in HEK 293 as well as in other cell lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008021428969
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  • 7
    Electronic Resource
    Electronic Resource
    Connectivity of the salamander pretectum: an in-vitro (whole-brain) intracellular tracing study (1998)
    Springer
    Cell & tissue research 292 (1998), S. 47-56 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Plethodontids ; Urodeles ; Optic tectum ; Electrophysiology ; Biocytin ; Salamander ; Plethodon jordani ; Hydromantes genei
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The amphibian optic tectum and pretectum have been analyzed in detail anatomically and physiologically, and a specific model for tecto-pretectal interaction in the context of the visual guidance of behavior has been proposed. However, anatomical evidence for this model, particularly the precise pattern of pretecto-tectal connectivity, is lacking. Therefore, we stained pretectal neurons intracellularly in an in-vitro preparation of the salamanders Plethodon jordani and Hydromantes genei. Our results demonstrate that the projections of neurons of the nucleus praetectalis profundus are divergent and widespread. Individual neurons may project divergently to telencephalic (ipsilateral amygdala and striatum), diencephalic (ipsi-and contralateral thalamus, contralateral pretectum), and mesencephalic (ipsi- and contralateral tectum and tegmentum) centers, and to the ipsi- and contralateral medulla oblongata and rostral spinal cord. The projection of pretectal cells to the optic tectum is bilateral; axonal structures do not show discernible patterns and are present in all layers of the superficial white matter. A classification of pretectal neurons on the basis of axonal termination pattern or dendritic arborization has not been possible. Our results do not support the hypothesis that a distinct class of pretectal neurons projects to a particular subset of tectal cells. Rather, the pretectum appears to influence the tectum indirectly, acting either on retinal afferents or modulating inhibitory interneurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051033
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