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  • 1995-1999  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Scandinavian journal of immunology 43 (1996), S. 0 
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Microencapsulated pancreatic Langerhan's islets in calcium alginate gels have been used as an implantable bio-artificial pancreas in the treatment of diabetes mellitus, but with limited success due to overgrowth of the capsule with fibroblasts and phagocytes. The authors earlier demonstrated that alginates enriched in mannuronic acid stimulate human monocytes to produce high levels of cytokines such as tumour necrosis factor (TNF), IL-1, IL-6. In this study the authors have measured the TNF production from peripheral blood mononuclear cells (PBMC) in different groups of insulin-dependent diabetes mellitus (IDDM) patients after stimulation with different alginates and lipopolysaccharide (LPS). It was found that high G-alginate did not induce TNF production in any of the groups. High-M alginate and LPS induced a dose-dependent TNF production in all groups and the production was significantly different from unstimulated cells. The highest TNF response was found in newly diagnosed IDDM patients and the lowest was in the controls.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 46 (1997), S. 0 
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mannuronan (poly-β-(1→4)-d-mannuronate or poly-M), produced by Pseudomonas aeruginosa as a mucoid exopolysaccharide, has previously been shown to exhibit immunostimulating activity. The authors investigated the in vivo and in vitro effects of mannuronan on murine haematopoiesis. In vivo, prophylactic (−24 h, intraperitoneal) administration of mannuronan enhanced survival of lethally irradiated mice from zero day 40 survivors (NaCl) to 20, 80 and 70% survival at 0.5, 1 and 2 mg/kg bw mannuronan, respectively. In vitro, primary stromal cultures stimulated with mannuronan produced high levels of interleukin(IL)-1, IL-6 and colony stimulating activity. Mannuronan alone did not have any colony stimulating activity on GM-CFC, BFU-E, Mix-CFC or HPP-CFC progenitors in clonogenic assays, but acted synergistically with suboptimal amounts of growth factors on GM-CFC, Mix-CFC and HPP-CFC colony formation. Limiting dilution analysis showed that 1 of 423 bone marrow cells formed colonies in response to suboptimal GM-CSF plus mannuronan compared to 1 of 592 for suboptimal GM-CSF alone. The primitive Lin−Sca-1+ haematopoietic progenitors showed increased day 10 colony size in the presence of mannuronan in single cell assays. These stimulating effects of mannuronan on haematopoiesis may prove to have clinical importance.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 438-446 
    ISSN: 0006-3592
    Keywords: DNA ; alginate ; encapsulation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alginate gels produced by an external or internal gelation technique were studied so as to determine the optimal bead matrix within which DNA can be immobilized for in vivo application. Alginates were characterized for guluronic/mannuronic acid (G/M) content and average molecular weight using 1H-NMR and LALLS analysis, respectively. Nonhomogeneous calcium, alginate, and DNA distributions were found within gels made by the external gelation method because of the external calcium source used. In contrast, the internal gelation method produces more uniform gels. Sodium was determined to exchange for calcium ions at a ratio of 2:1 and the levels of calcium complexation with alginate appears related to bead strength and integrity. The encapsulation yield of double-stranded DNA was over 97% and 80%, respectively, for beads formed using external and internal calcium gelation methods, regardless of the composition of alginate. Homogeneous gels formed by internal gelation absorbed half as much DNAse as compared with heterogeneous gels formed by external gelation. Testing of bead weight changes during formation, storage, and simulated gastrointestinal (GI) conditions (pH 1.2 and 7.0) showed that high alginate concentration, high G content, and homogeneous gels (internal gelation) result in the lowest bead shrinkage and alginate leakage. These characteristics appear best suited for stabilizing DNA during GI transit. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 438-446, 1998.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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