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  • Articles: DFG German National Licenses  (4)
  • diabetes mellitus.  (2)
  • morphology  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Physical state and biodegradation behavior of starch-polycaprolactone systems (1995)
    Springer
    Journal of polymers and the environment 3 (1995), S. 81-95 
    Details
    ISSN: 1572-8900
    Keywords: Biodegradation ; poly-ε-caprolactone ; starch ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The biodegradation behavior of insoluble crystalline polymers depends on both chemical structure and physical state. The physical state is strongly affected by the molding conditions; moreover the presence of natural hydrophylic substances such as starch can further influence the biodegradation process. This paper examines the biotic and abiotic degradation of thick injection-molded parts, made of pure poly-ε-caprolactone (PCL) at different molecular weights, and of PCL in the presence of starch in the case of a commercial grade of Mater-Bi, produced by Novamont. The abiotic degradation was studied at 25 and 50°C, whereas the biotic degradation was followed in conditions of SCAS (semicontinuous activated sludges) at 25 and 50°C, soil burial, and controlled composting. The physical-chemical modifications provoked at the surface and in the bulk of the samples by the different types of degradation were determined by differential scanning calorimetry, viscometric and gravimetric analysis, scanning electron microscopy, and dynamic mechanical analysis. The mechanical modifications induced by the different environments were followed by tensile tests. It was demonstrated that the presence of starch significantly increases the apparent biodegradation rate of PCL, making even thick parts of ZI01U compatible with the composting process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02067484
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Increased activity of the insulin-like growth factor system in mesangial cells cultured in high glucose conditions. Relation to glucose-enhanced extracellular matrix production (1996)
    Springer
    Diabetologia 39 (1996), S. 775-784 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Insulin-like growth factor-I ; II ; binding proteins ; receptors ; transforming growth factor-b ; extracellular matrix ; mesangial cell ; diabetes mellitus.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent evidence suggests that several growth factors participate in diabetic glomerular disease by mediating increased extracellular matrix accumulation and altered cell growth and turnover leading to mesangial expansion. Transforming growth factor (TGF)-β has been demonstrated to be upregulated both in vivo and in vitro, whereas studies on the activity of the renal insulin-like growth factor (IGF) system in experimental diabetes have provided conflicting results. We investigated the effects of prolonged exposure (4 weeks) of cultured human and rat mesangial cells to high (30 mmol/l) glucose vs iso-osmolar mannitol or normal (5.5 mmol/l) glucose levels on: 1) the autocrine/paracrine activity of the IGF system (as assessed by measuring IGF-I and II, IGF-I and II receptors, and IGF binding proteins); and, in parallel, on 2) TGF-β1 gene expression; 3) matrix production; and 4) cell proliferation. High glucose levels progressively increased the medium content of IGF-I and the mRNA levels for IGF-I and IGF-II, increased IGF-I and IGF-II binding and IGF-I receptor gene expression, and reduced IGF binding protein production. TGF-β1 transcripts and matrix accumulation and gene expression were increased in parallel, whereas cell proliferation was reduced. Iso-osmolar mannitol did not affect any of the above parameters. These experiments demonstrated that high glucose levels induce enhanced mesangial IGF activity, together with enhanced TGF-β1 gene expression, increased matrix production, and reduced cell proliferation. It is possible that IGFs participate in mediating diabetes-induced changes in matrix turnover leading to mesangial expansion, by acting in a paracrine/autocrine fashion within the glomerulus. [Diabetologia (1996) 39: 775–784]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250050510
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Regulatory role of eicosanoids in extracellular matrix overproduction induced by long-term exposure to high glucose in cultured rat mesangial cells (1996)
    Springer
    Diabetologia 39 (1996), S. 1055-1062 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Extracellular matrix ; transforming growth factor-β ; prostaglandins ; thromboxane ; mesangial cell ; diabetes mellitus.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Accumulation of extracellular matrix in the mesangium and altered renal eicosanoid synthesis are two prominent features of diabetic glomerular disease. We investigated the relationship between eicosanoid and extracellular matrix production in rat mesangial cells cultured under high glucose vs normal glucose conditions. Long-term exposure of rat mesangial cells to high glucose, but not to iso-osmolar mannitol, significantly increased extracellular matrix accumulation and gene expression and transforming growth factor-β (TGF-β) mRNA levels, and decreased prostaglandin (PG) E2 synthesis without affecting production of either thromboxane (TX) B2 or PGF2 a, with respect to cells incubated in normal glucose. Addition of exogenous PGE2 resulted in a dose-dependent reduction of matrix protein and mRNA levels and TGF-β gene expression in cells cultured in either normal or high glucose conditions, whereas exposure to exogenous PGF2α produced a significant increment in matrix production and matrix and TGF-β gene expression in cells grown in normal glucose, but only a slight increase in those cultured in high glucose. Stimulation of endogenous endoperoxide metabolism towards PGE2 and PGF2α synthesis with FCE-22,178, a drug originally developed as TXA2 synthase inhibitor, resulted in a dose-dependent decrease in matrix accumulation and matrix and TGF-β gene expression which was suppressed by co-incubation with the cyclo-oxygenase inhibitor fenoprofen blocking the FCE-22,178-enhanced PG production. In both cell lines, the rate of synthesis of TXA2 was very low and the selective blockade of its synthesis (by two other TXA2 synthase inhibitors, OKY-046 and Ridogrel) or action (by the TXA2 receptor antagonist BM-13,177) did not alter matrix production or TGF-β mRNA levels. These results suggest that the cyclo-oxygenase pathway is involved in the regulation of matrix changes induced by high glucose in rat mesangial cells; the reduced production of PGE2 may enhance the synthesis or potentiate the effect of stimulators of ECM formation such as TGF-β, whereas TXA2 does not appear to be involved. These data also indicate that glucose-enhanced mesangial matrix accumulation may be prevented by exogenous PGE2 or by drugs capable of increasing endogenous PGE2 synthesis. [Diabetologia (1996) 39: 1055–1062]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400654
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Monoaxial drawing behaviour of isotactic polypropylene quenched at different temperatures (1987)
    Springer
    Colloid & polymer science 265 (1987), S. 696-703 
    Details
    ISSN: 1435-1536
    Keywords: Isotacticpolypropylene ; morphology ; drawing ; fibers properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Quenched films of isotactic polypropylene were obtained in different quenching conditions; the films structure was analyzed in terms of phases composition and gross morphology. The mechanical behaviour, analyzed at room temperature in monoaxial drawing shows that the initial structure strongly affects the drawing behaviour. The drawing occurs by necking propagation in all the samples, but the deformation in the neck depends on the gross morphology while the drawing load depends on crystallinity. The obtianed results are discussed on the basis of the molecular and structural model of the fibers formation by drawing of crystalline polymeric films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01425031
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    Paper (German National Licenses)
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