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  • Electronic Resource  (4)
  • 1990-1994  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Choline Uptake by Cerebral Capillary Endothelial Cells in Culture (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A passage of choline from blood to brain and vice versa has been demonstrated in vivo. Because of the presence of the blood-brain barrier, such passage takes place necessarily through endothelial cells. To get a better understanding of this phenomenon, the choline transport properties of cerebral capillary endothelial cells have been studied in vitro. Bovine endothelial cells in culture were able to incorporate [3H]choline by a carrier-mediated mechanism. Nonlinear regression analysis of the uptake curves suggested the presence of two transport components in cells preincubated in the absence of choline. One component showed a Km of 7.59 ± 0.8 μM and a maximum capacity of 142.7 ± 9.4 pmol/2 min/mg of protein, and the other one was not saturable within the concentration range used (1–100 μM). When cells were preincubated in the presence of choline, a single saturable component was observed with a Km of 18.5 ± 0.6 μM and a maximum capacity of 452.4 ± 42 pmol/2 min/mg of protein. [3H]Choline uptake by endothelial cells was temperature dependent and was inhibited by the choline analogs hemicholinium-3, deanol, and AF64A. The presence of ouabain or 2,4-dinitrophenol did not affect the [3H]choline transport capacity of endothelial cells. Replacement of sodium by lithium and cell depolarization by potassium partially inhibited choline uptake. When cells had been preincubated without choline, recently transported [3H]choline was readily phosphorylated and incorporated into cytidine-5′-diphosphocholine and phospholipids; however, under steady-state conditions most (63%) accumulated [3H]choline was not metabolized within 1 h. Only part of the labelled intracellular free choline was transported back into the incubation medium. Because of their special location, transport properties, and metabolism, cerebral capillary endothelial cells may provide a gating mechanism that can contribute to the physiological control of choline concentration in the brain extracellular fluid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb01193.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Selective involvement of monocytes by acquired myeloperoxidase deficiency in a case of chronic myelomonocytic leukemia (1993)
    Springer
    Annals of hematology 66 (1993), S. 261-264 
    Details
    ISSN: 1432-0584
    Keywords: Myeloperoxidase deficiency ; Chronicmyelomonocytic leukemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors describe a case of chronic myelomonocytic leukemia in which a myeloperoxidase (MPO) deficiency of circulating monocytes was first detected by automated differential cell counting, and subsequently confirmed by cytochemical and immunocytochemical investigations. MPO activity in neutrophil granulocytes from the same case was found to be normal. MPO deficiency in monocytes appeared to be associated with impaired phagocytic capacity and, based on the results of immunophenotypic and ultrastructural studies, was most likely attributable to a partial maturation arrest of monocytes. The present case suggests that MPO deficiency in myelodysplastic syndromes may have its origin in a number of different pathogenetic mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01738477
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Fully imidized soluble polyimides based on a novel dianhydride: 2,2′-dichloro-4,4′,5,5′-benzophenone tetracarboxylic dianhydride (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1433-1441 
    Details
    ISSN: 0887-624X
    Keywords: polyimides ; increased solubility ; non-coplanar synthesis ; high temperature ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have synthesized a novel dianhydride, 2,2′-dichloro-4,4′,5,5′-benzophenone tetracarboxylic dianhydride (DCBTDA). Polyimides were synthesized with DCBTDA or 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and several relatively rigid meta- and para- substituted mononuclear diamines. The BTDA based systems were insoluble in dipolar, aprotic solvents whereas the DCBTDA based polymers displayed enhanced solubility in these solvents. The thermal stability of these polyimides was excellent as measured by 5% weight loss decomposition. The Tg's of the polymers were all above 290°C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300723
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  • 4
    Electronic Resource
    Electronic Resource
    Novel auto-photosensitive polyimides with tailored properties (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 1623-1629 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: An overview is given on auto-photosensitive polyimides as introduced for the first time in 1985. It is shown how development proceeded and how the chemical basis of auto-photosensitive polyimides was extended beyond BTDA. Novel “photosensitizer tetracarboxylic dianhydrides” like 2,3,6,7-thioxanthonetetracarboxylic dianhydride (TXDA) were synthesized and copolymerized into preimidized nonphotoactive polyimides containing tetracarboxylic acids like 6FDA or ODPA. Novel photosensitive polyimides were obtained that carry all essential features of BTDA based systems plus higher photospeed. They provide the ability to better tailor material properties to specific applications.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760322115
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