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  • 1
    Electronic Resource
    Electronic Resource
    Apoptosis and beta-cell destruction in pancreatic islets of NOD mice with spontaneous and cyclophosphamide-accelerated diabetes (1998)
    Springer
    Diabetologia 41 (1998), S. 1381-1388 
    Details
    ISSN: 1432-0428
    Keywords: Keywords NOD mouse ; beta-cell apoptosis ; diabetes ; T cells ; cyclophosphamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Autoimmune-mediated destruction of pancreatic islet beta cells leads to insulin-dependent diabetes in non-obese diabetic (NOD) mice. Although both direct cytotoxic T cell- and indirect cytokine-, nitric oxide- or free radical-mediated mechanisms induce beta-cell apoptosis in vitro, beta-cell death in vivo in spontaneous autoimmune diabetes is not well-characterized. Furthermore, whether beta cells die gradually, or rapidly in the late pre-clinical stage, is a question of current interest. To investigate beta-cell death in vivo, we measured the frequency and intra-islet localisation of apoptosis, defined as DNA strand breaks by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) technique, during spontaneous and cyclophosphamide-accelerated diabetes in NOD mice. In spontaneous diabetes, the frequency of apoptosis in islets correlated with the progression of beta-cell destruction with age. Although apoptosis was detected at low frequency within the reduced insulin-positive islet area of pre-diabetic mice at 90 days of age, it was rarely co-localised to beta cells. After acceleration of beta-cell destruction with cyclophosphamide, the frequency of apoptosis reached maximum at 12 days, at which time 3.2 % of apoptotic cells were beta cells. Apoptosis was most frequent in the insulin-negative islet area comprised of mononuclear cell infiltrate and was localized to CD8+ T cells. The rarity of detectable apoptotic beta cells in spontaneous pre-diabetic mice with pronounced insulitis and reduced insulin-positive islet areas most likely reflects the rapid clearance of apoptotic beta cells. Our findings are more consistent with gradual destruction of non-renewable beta-cells in spontaneous diabetes, than with their rapid, accelerated destruction (as after cyclophosphamide) in the late pre-clinical stage. [Diabetologia (1998) 41: 1381–1388]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250051080
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Murine monoclonal glutamic acid decarboxylase (GAD)65 antibodies recognize autoimmune-associated GAD epitope regions targeted in patients with type 1 diabetes mellitus and Stiff-man syndrome (1996)
    Springer
    Acta diabetologica 33 (1996), S. 225-231 
    Details
    ISSN: 1432-5233
    Keywords: Key words Murine monoclonal glutamate decarboxylase antibodies ; Autoantibodies ; Type 1 diabetes mellitus ; Stiff-man syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To study the immune response to glutamic acid decarboxylase (GAD) in insulin-dependent diabetes mellitus, monoclonal GAD antibodies after fusion of splenocytes from a nondiabetes-susceptible BALB/c mouse immunized with human recombinant GAD65 were generated. Of the 44 monoclonals, 35 are specific for the GAD65 isoform, whereas 9 also react with GAD67. Some 37 monoclonals, including all GAD65/67 reactive antibodies, react with GAD by Western blot analysis. The remaining 7 GAD65 monoclonals bind GAD only in an immunoprecipitation assay, which implies that they target epitopes dependent on the conformation of the GAD molecule. The 125I-GAD binding of the GAD65 monoclonals reactive on Western blotting was significantly diminished by all 3 sera from Stiff-man syndrome patients but only by 3/30 (10%) sera from type 1 diabetic patients. In contrast, the 7 monoclonal antibodies reactive with a conformation-dependent GAD epitope were competitive with 83% of GAD-autoantibody-positive sera from these diabetic patients. Using chimeric GAD65/67 proteins, the epitope region targeted by these monoclonals was mapped to the middle of GAD65 (amino acids 221–442). This central conformation-dependent GAD region was also targeted by sera from patients with type 1 diabetes. In conclusion, our data show that even after common immunization of a nondiabetes-susceptible mouse strain, monoclonals were obtained which preferentially react with the GAD65 linear amino-terminus (amino acids 4–17) and a conformation-dependent region located in the middle of GAD targeted by autoantibodies, indicating that this GAD region is not restricted to the autoimmune response associated with the Stiff-man syndrome and the beta-cell destruction in type 1 diabetes mellitus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02048548
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of monoclonal islet cell reactive autoantibodies from the diabetic biobreeding (BB/OK) rat (1993)
    Springer
    Acta diabetologica 30 (1993), S. 201-206 
    Details
    ISSN: 1432-5233
    Keywords: Diabetes-prone BB rats ; Displacement ; Human diabetic sera ; Monoclonal islet cell reactive autoantibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two fusion experiments using the heteromyeloma cell line CB-F7 and splenocytes from two diabetesprone BB (BioBreeding) rats at the onset of diabetes resulted in 128 islet cell reactive autoantibodies primarily detected with permeabilized insulin-producing rat insulinoma cells (RIN) by a cellular enzyme-linked immunosorbent assay. Seventy-nine (62%) of 128 RIN cell reactive supernatants exhibited a cross-reactivity with rat splenic lymphocytes. Six stable hybridomas secreting monoclonal ICSA (islet cell surface antibodies) were established, but only one monoclonal antibody, R4B10, showed preferential beta-cell binding. Six monoclonal antibodies showed a dual reactivity as ICA (islet cell cytoplasmic antibodies) detected by immunostaining of pancreatic islet cryosections and as ICSA on the surface of viable islet cells, whereas two reacted only with an ICA-like pattern. One monoclonal ICSA was specifically displaced from the RIN cell surface by sera of type 1 diabetic patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00569930
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Murine monoclonal glutamic acid decarboxylase (GAD)65 antibodies recognize autoimmune-associated GAD epitope regions targeted in patients with type 1 diabetes mellitus and Stiff-man syndrome (1996)
    Springer
    Acta diabetologica 33 (1996), S. 225-231 
    Details
    ISSN: 1432-5233
    Keywords: Murine monoclonal glutamate decarboxylase antibodies ; Autoantibodies ; Type 1 diabetes mellitus ; Stiff-man syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To study the immune response to glutamic acid decarboxylase (GAD) in insulin-dependent diabetes mellitus, monoclonal GAD antibodies after fusion of splenocytes from a nondiabetes-susceptible BALB/c mouse immunized with human recombinant GAD65 were generated. Of the 44 monoclonals, 35 are specific for the GAD65 isoform, whereas 9 also react with GAD67. Some 37 monoclonals, including all GAD65/67 reactive antibodies, react with GAD by Western blot analysis. The remaining 7 GAD65 monoclonals bind GAD only in an immunoprecipitation assay, which implies that they target epitopes dependent on the conformation of the GAD molecule. The125I-GAD binding of the GAD65 monoclonals reactive on Western blotting was significantly diminished by all 3 sera from Stiff-man syndrome patients but only by 3/30 (10%) sera from type 1 diabetic patients. In contrast, the 7 monoclonal antibodies reactive with a conformation-dependent GAD epitope were competitive with 83% of GAD-autoantibody-positive sera from these diabetic patients. Using chimeric GAD65/67 proteins, the epitope region targeted by these monoclonals was mapped to the middle of GAD65 (amino acids 221–442). This central conformation-dependent GAD region was also targeted by sera from patients with type 1 diabetes. In conclusion, our data show that evne after common immunization of a nondiabetes-susceptible mouse strain, monoclonals were obtained which preferentially react with the GAD65 linear amino-terminus (amino acids 4–17) and a conformation-dependent region located in the middle of GAD targeted by autoantibodies, indicating that this GAD region is not restricted to the autoimmune response associated with the Stiff-man syndrome and the bete-cell destruction in type 1 diabetes mellitus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02048548
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Impact of metabolic activity of beta cells on cytokine-induced damage and recovery of rat pancreatic islets (1995)
    Springer
    Acta diabetologica 32 (1995), S. 217-224 
    Details
    ISSN: 1432-5233
    Keywords: Cytokine ; Islet of Langerhans ; Insulin secretion ; Nitrite ; Heat shock proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The influence of beta cell activity on cytokineinduced functional and structural impairments as well as the ability of those damaged cells to recover were investigated. Rat islets cultured for 4 days in the presence of 5, 10, and 30 mmol/l glucose were exposed to interferon-γ (IFN, 500 U/ml) and tumor necrosis factor-α (TNF, 250 U/ml) for the last 24 h. After cytokine removal islets were allowed to recover spontaneously in culture medium containing 10 mmol/l glucose for a further 7 days. Cytokines significantly inhibited insulin release into culture medium, insulin storage, glucose-stimulated insulin secretion, protein, and DNA synthesis. In the presence of cytokines there was a six- to eightfold increase in nitrite production by the islets. The functional impairments were more pronounced in metabolically stimulated beta cells. In addition, cytokines caused membrane alterations as indicated by increased spontaneous chromium-51 release. The cytokines specifically induced the synthesis of two proteins (72 and 88 kDa, respectively). By immunoblotting, the 72-kDa protein was identified as heat shock protein. After a 1-week recovery period, insulin storage and stimulated insulin secretion of cytokine-treated islets were still significantly diminished. However, protein and DNA synthesis of cytokine-exposed islets returned to pre-exposure levels. In conclusion, high beta cell activity increases islet susceptibility to TNF+IFN. Cytokine-induced, longlasting, inhibitory effects are primarily directed to betacell-specific functions, while general vital cell functions clearly recover after cytokine removal. The induction of certain proteins and the increased protein synthesis and replication rate after cytokine removal might reflect activated repair processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00576253
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    Paper (German National Licenses)
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