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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Rheumatology international 13 (1993), S. 5-8 
    ISSN: 1437-160X
    Schlagwort(e): Arthritis ; Cytokines ; Chondrocytes ; Growth factors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Leukaemia inhibitory factor (LIF) is a secretory glycoprotein produced by tumour, mesenchymal and haemopoietic cells. LIF has been found to have pleiotropic actions that include the capacity to regulate cell differentiation, promote acute-phase protein synthesis and stimulate calcium release in bone explants. In view of its similarity to other cytokines that affect cartilage metabolism, the effects of LIF on proteoglycan resorption were examined in pig cartilage explants. Endotoxinfree recombinant mouse LIF was found to produce a dose-dependent increase in sulphated glycosaminoglycan (S-GAG) release (ED50=123 U/ml, approx. 25–50 pM). Statistically significant stimulation was observed with doses of 100 U/ml or greater. When pig cartilage was stimulated with maximum concentrations of LIF and either interleukin 1α (IL-1α), interleukin 1β (IL-1β) or tumour necrosis factor α (TNFα), in each case a significantly greater release of S-GAGs was observed than with the respective cytokines alone (P〈0.05). Comparison of the areas under the curves showed that the action of LIF was additive, and not synergistic with other catabolic cytokines. Dose-response studies showed that transforming growth factor β (TGFβ) produced a partial inhibition of LIF-stimulated release of S-GAGs (ED50=4.5 U/ml). Statistically significant inhibition was observed with doses of 2U/ml or greater. These results showed that LIF stimulated proteoglycan resorption in vitro and that this effect was modulated by other cytokines. Whether LIF contributes to the progressive destruction of cartilage in septic or chronic inflammatory arthritis remains to be determined.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1573-5036
    Schlagwort(e): growth ; nutrition ; peanuts ; phosphorus ; VA mycorrhizae ; zinc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Peanut plants (cv. Shulamit) were grown in an Oxisol soil in pots in the glasshouse to assess effects of soil sterilization and inoculation with spores of vesicular-arbuscular mycorrhizal fungi (VAMF) on the response to five rates of phosphorus (0 to 240 kg P ha−1) and two rates of zinc (0 and 10 kg Zn ha−1) fertilizers. Both P and Zn nutrition were affected by VAMF activity but the dominant role of VAMF in this soil type was in uptake of P. In the absence of VAMF there was a clear threshold level of P application (60 kg P ha−1) below which plants grew poorly, which resulted in a sigmoidal response of dry matter to applied P. The maximum response was not fully defined because dry matter production continued to increase up to 240 kg P ha−1. Tissue P concentration of non-mycorrhizal plants increased linearly with P rate and was always significantly less than that in mycorrhizal plants. Mycorrhizal plants responded without threshold to increasing P rate, attaining maximum dry matter at 120 kg P ha−1 in inoculated sterilized soil and at 30 kg P ha−1 in nonsterile soil. These differences in maximal P rates and in the greater dry matter produced in sterile soil at high P rates were attributed to the negative effects of the root-knot nematodeMeloidogyne hapla in nonsterile soil. Plant weight did not respond to zinc fertilizer but tissue Zn concentration increased with applied Zn. Tissue Zn concentration and uptake were increased by VAMF.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1573-5036
    Schlagwort(e): fumigation, growth ; VA mycorrhizae ; peanut ; sterilization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The effects of soil sterilization and inoculation with vesicular-arbuscular mycorrhizal fungi (VAMF) on VAMF colonization, nutrition and growth of peanut plants (cv. Virginia Bunch) were investigated in an Oxisol soil in pots in the glasshouse. Sterilization, nutrient and inoculation treatments were applied to soil with a history of either continuous summer cropping (〉50 years) or continuous grass pasture. Root colonization by VAMF was strongly affected by sterilization of soil from both cropping histories. Irradiation and aerated steam treatments virtually eliminated VAMF colonization; methyl bromide+chloropicrin caused an early reduction in colonization which was no longer visible twenty-one days after flowering; and DD+methyl isothiocyanate caused no significant reduction. Despite earlier differences in VAMF colonization of roots, plant growth responses were not recorded until after flowering. Plant growth 21 days after flowering was strongly correlated with VAMF colonization at first flower and at 21 days after first flower. Effective soil sterilization caused significant reductions in plant growth which were eliminated by addition of VAMF inoculum. Growth reductions in the absence of VAMF could be directly related to severe P deficiency, which was reflected in P uptake as early as first flower; Zn uptake was also reduced. Although VAMF colonization was slightly higher in grassland than in continuously cropped soil, growth responses to VAMF inoculation were not observed in unsterilized soil regardless of cropping history, indicating a general adequacy of resident VAMF populations. Plants grew better in untreated cropped soil than in grassland soil although growth was poor in both after effective soil sterilization. These differences could be related to the higher level of available P in the cropped soil and the inability of plants to access this P in the absence of VAMF. Regular applications of N-free nutrient solution had no effect on plant growth even in effectively sterilized soil, suggesting a threshold response to P in the absence of VAMF in this soil.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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