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  • Key words Dead roots  (1)
  • Polymer and Materials Science  (1)
  • matrix metalloproteinase  (1)
  • 1995-1999  (3)
  • 1
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Poly(oxytetramethylen), 4,4′-Bibenzyldiisocyanat, N-Methyldiethanolamin als Kettenverlängerer und Acrylsäure/Polyacrylsäure als Quaternisierungsagens wurden Poly(etherurethan)-Kationomere hergestellt. In aus diesen Kationomeren hergestellten Filmen wurde Pyrrol (15 Gew.-%) in Gegenwart von CuCl2 polymerisiert. Die Filme wurden mittels dynamisch-mechanischer Analyse, Thermogravimetrie und Differentialthermoanalyse charakterisiert. Die elektrische Leitfähigkeit beträgt für den Film ohne Polypyrrol 7.5 · 10-12 Ω-1 cm-1 und mit Polypyrrol 4.5 · 10-6 Ω-1 cm-1.
    Notes: Poly(ether urethane) cationomers based on poly(oxytetramethylene), 4,4′-bibenzyldiisocyanate, N-methyldiethanolamine as chain extender, and acrylic acid/poly(acrylic acid) as quaternization agent were synthesized. Pyrrole (15 wt.%%) was polymerized in films of the ionomer containing CuCl2. The films were characterized by dynamic mechanical analysis, thermogravimetry and differential scanning calorimetry. The electric conductivity of the film without polypyrrole is 7.5 · 10-12 Ω-1 cm-1, while incorporation of polypyrrole increases the conductivity to 4.5 · 10-6 Ω-1 cm-1.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0789
    Keywords: Key words Dead roots ; Fluorescein diacetate-active hyphae ; Field mesocosms ; Live roots ; Mor humus ; Mycorrhizae ; New Jersey Pinelands ; Spodosolic forest soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of live and dead roots on soil fungi were investigated experimentally in a spodosolic soil of the New Jersey Pinelands. Field mesocosm plots were constructed to have a layer of either C- and N-rich organic soil or a vermiculite substitute overlying a layer of sandy mineral soil with a very low organic content. The plots were also supplied with live pitch pine and blueberry roots or dead pitch pine roots in varying quantities based on naturally occurring densities (half, same, and double the ambient quantities). All plots were sampled 1 year after construction (June 1991), and three more times in two subsequent years (November 1991, June 1992, June 1993). In the presence of live roots, fluorescein diacetate-determined (FDA-active) fungal hyphae, total fungal hyphae, and soil moisture decreased significantly in the organic material, while no change was associated with the dead roots. The FDA-active fungal length in the live-root plots ranged from 40 to 165 m g–1 soil, and from 55 to 335 m g–1 soil in the dead-root plots. While the total fungal length in live-root plots remained constant over time (∼3000 m g–1 soil), the total fungal length in the dead-root plots increased from an initial value of 3000 to 〉4000 m g–1 soil at the conclusion of the study. Fungal lengths in mineral soil were higher under organic material than under the vermiculite substitute. Soil moisture was higher in the presence of live roots in mineral soils, but this did not increase the fungal abundance. Inputs of dead roots did not alter the fungal abundance. Overall, we demonstrated that live and dead roots had different effects on fungal abundance in soils with contrasting qualities, and in a spodosolic forest soil, roots could have ecosystem effects very different from those in agricultural soils.
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  • 3
    ISSN: 1432-0428
    Keywords: Keywords Glomerulosclerosis ; matrix metalloproteinase ; tissue inhibitor of metalloproteinases ; obese Zucker rat.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The obese Zucker rat represents a model of obesity combined with insulin resistance and hyperlipidaemia, which over a period of several months develops spontaneous glomerulosclerosis. The present study addressed the question as to whether glomerular sclerosis was associated with alterations in the degradation of matrix components. In the early phase (up to 6 months) glomeruli from obese rats displayed increased total collagen content (+ 64 %) and decreased gelatinolytic activity (− 34 %) as compared to lean control animals. This decline in glomerular gelatinolytic activity was due to a reduction in gelatinase B [matrix metalloproteinase (MMP)-9]. Glomerular MMP-9 mRNA was reduced 4.6 ± 0.6-fold (n = 3; p 〈 0.05), MMP-9 protein was not detectable by Western blotting and MMP-9 activity was considerably suppressed in gelatin zymograms. MMP-2, in terms of mRNA expression and activity, was unchanged. Tissue inhibitor of metalloproteinases (TIMP)-1 mRNA expression, TIMP-1 protein (immunohistochemistry) and TIMP-1 activity (reverse zymography) were enhanced in glomeruli from obese rats, while TIMP-2 mRNA remained unchanged. Moreover, mRNA for the α1 IV collagen chain was 2.1 ± 0.8-fold higher in glomeruli isolated from obese animals (n = 3; p 〈 0.05). These findings indicate that matrix expansion in glomeruli from obese Zucker rats is due to both enhanced synthesis of matrix components as well as reduced degradation by matrix metalloproteinases. Apparently the latter effect is based on a reduction in MMP-9 and up-regulation of its inhibitor TIMP-1. [Diabetologia (1997) 40: 1035–1043]
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