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  • Articles  (4)
  • PMMA-ZrO2  (2)
  • SRIF-binding  (2)
  • 1995-1999  (4)
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  • Articles  (4)
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  • 1995-1999  (4)
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  • 1
    ISSN: 1573-4846
    Keywords: ormocer ; coatings ; chemical protection ; stainless steel ; PMMA-ZrO2 ; corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The chemical protection of 316 L stainless steel coated with ORMOCER coatings of polymethylmethacrylate (PMMA) and ZrO2 has been verified. The coatings were dip-coated on the substrates from sols prepared by mixing zirconium propoxide (ZrOC3H7)4, isopropanol (C3H7OH), glacial acetic acid (CH3COOH), polymethylmethacrylate and water under application of ultrasounds. The films were heat treated between 40 and 300°C in air up to 20 h. Their morphology was studied by electron scanning microscopy (SEM). Their anticorrosion behavior was analysed in 0.5M-H2SO4 solutions through potentiodynamic polarization curves at room temperature. The influence of the sol preparation, coating composition as well as of the duration and temperature of heat treatments on the corrosion parameters is reported. The films act as geometric blocking layers against the corrosive media and increase the lifetime of the substrate up to a factor 30.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-4846
    Keywords: ormocer ; coatings ; chemical protection ; stainless steel ; PMMA-ZrO2 ; corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The chemical protection of 316 L stainless steel coated with ORMOCER coatings of polymethylmethacrylate (PMMA) and ZrO2 has been verified. The coatings were dip-coated on the substrates from sols prepared by mixing zirconium propoxide (ZrOC3H7)4, isopropanol (C3H7OH), glacial acetic acid (CH3COOH), polymethylmethacrylate and water under application of ultrasounds. The films were heat treated between 40 and 300°C in air up to 20 h. Their morphology was studied by electron scanning microscopy (SEM). Their anticorrosion behavior was analysed in 0.5M-H2SO4 solutions through potentiodynamic polarization curves at room temperature.The influence of the sol preparation, coating composition as well as of the duration and temperature of heat treatments on the corrosion parameters is reported. The films act as geometric blocking layers against the corrosive media and increase the lifetime of the substrate up to a factor 30.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1912
    Keywords: Somatostatin ; BIM-23027 ; Rat colonic mucosa ; sst2 receptors ; SRIF-binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have previously shown that the somatostatin (SRIF) sst2 receptor-selective peptide, BIM-23027, is a potent antisecretory agent in rat isolated distal colonic mucosa (RDCM) and in radioligand binding studies in RDCM membranes, it only maximally inhibited approximately 40% of [125I]-Tyr11-SRIF-14 binding (McKeen ES, Feniuk W, Humphrey PPA (1995) Naunyn-Schmiedeberg's Arch Pharmacol 352:402–411). The aim of this study was to characterise the BIM-23027-sensitive and -insensitive SRIF binding sites in more detail and to compare their properties with those of the recombinant sst2 receptor stably expressed in mouse fibroblast (Ltk−) cells. SRIF-14, SRIF-28, CGP-23996 and D Trp8-SRIF-14 abolished [125I]-Tyr11-SRIF-14 binding (pIC50 values, 8.7–9.7) but the competition curves had Hill slopes which were less than unity. Octreotide and L-362,855 inhibited binding over a wide concentration range (0.1 nM-1 μM) and inhibition of binding was incomplete at the highest concentration studied. BIM-23056 (PIC50 〈6.5) was a weak inhibitor of [125]-Tyr11-SRIF-14 binding. GTPγS decreased [125I]-Tyr11-SRIF-14 binding by 40%. Further binding experiments with [125I]-Tyr11-SRIF-14 were carried out in RDCM in the continuous presence of BIM-23027 (1 μM). Under these conditions, seglitide had no effect on [125I]-Tyr11-SRIF-14 binding at concentrations up to 10 μM, whilst SRIF-14 and SRIF-28 abolished specific [125I]-Tyr11-SRIF-14 binding in a manner which was consistent with the ligand binding to two sites. SRIF-14 and SRIF-28 displayed high affinity (pIC50 values of 9.8 and 9.3 respectively) for approximately 70% of these binding sites and low affinity (pIC50 values of 7.8 and 7.3) for the remaining sites. Octreotide, L-362,855 and BIM-23056 were weak inhibitors of [125I]-Tyr11-SRIF-14 binding (PIC50 〈6.5). [125I]-BIM-23027 labelled a single population of SRIF binding sites in RDCM membranes and mouse fibroblast (Ltk−) cells stably expressing the human recombinant sst2 receptor. There was a significant correlation between the affinitestimates of a range of SRIF analogues at inhibiting [125I]-BIM-23027 binding in RDCM membranes and binding to the recombinant sst2 receptor in Ltk− cells, suggesting that the sites labelled by [125I]-BIM-23027 in RDCM are similar to the sst2 receptor. GTPγS (100 μM) decreased [125I]-BIM-23027 binding in RDCM by 60%. The results from these studies demonstrate that [125I]-Tyr11-SRIF-14 labels a heterogeneous population of high affinity SRIF binding sites in RDCM membranes. The majority of these sites are insensitive to GTPγS and display negligible affinity for the cyclic hexapeptides, BIM-23027 and seglitide. The remaining high affinity binding sites can be selectively labelled with [125I]-BIM-23027, are sensitive to GTPγS and show similar characteristics to the recombinant sst2 receptor which appears to mediate the antisecretory effects of SRIF in the mucosa (McKeen ES, Feniuk W, Humphrey PPA (1995) Naunyn-Schmiedeberg's Arch Pharmacol 352:402–411).
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  • 4
    ISSN: 1432-1912
    Keywords: Key words Somatostatin ; BIM-23027 ; Rat colonic mucosa ; sst2 receptors ; SRIF-binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have previously shown that the somatostatin (SRIF) sst2 receptor-selective peptide, BIM-23027, is a potent antisecretory agent in rat isolated distal colonic mucosa (RDCM) and in radioligand binding studies in RDCM membranes, it only maximally inhibited approximately 40% of [125I]-Tyr11-SRIF-14 binding (McKeen ES, Feniuk W, Humphrey PPA (1995) Naunyn-Schmiedeberg‘s Arch Pharmacol 352:402–411). The aim of this study was to characterise the BIM-23027-sensitive and -insensitive SRIF binding sites in more detail and to compare their properties with those of the recombinant sst2 receptor stably expressed in mouse fibroblast (Ltk–) cells. SRIF-14, SRIF-28, CGP-23996 and D Trp8-SRIF-14 abolished [125I]-Tyr11-SRIF-14 binding (pIC50 values, 8.7–9.7) but the competition curves had Hill slopes which were less than unity. Octreotide and L-362,855 inhibited binding over a wide concentration range (0.1 nM-1 μM) and inhibition of binding was incomplete at the highest concentration studied. BIM-23056 (pIC50 〈6.5) was a weak inhibitor of [125]-Tyr11-SRIF-14 binding. GTPγS decreased [125I]-Tyr11-SRIF-14 binding by 40%. Further binding experiments with [125I]-Tyr11-SRIF-14 were carried out in RDCM in the continuous presence of BIM-23027 (1 μM). Under these conditions, seglitide had no effect on [125I]-Tyr11-SRIF-14 binding at concentrations up to 10 μM, whilst SRIF-14 and SRIF-28 abolished specific [125I]-Tyr11-SRIF-14 binding in a manner which was consistent with the ligand binding to two sites. SRIF-14 and SRIF-28 displayed high affinity (pIC50 values of 9.8 and 9.3 respectively) for approximately 70% of these binding sites and low affinity (pIC50 values of 7.8 and 7.3) for the remaining sites. Octreotide, L-362,855 and BIM-23056 were weak inhibitors of [125I]-Tyr11-SRIF-14 binding (pIC50 〈6.5). [125I]-BIM-23027 labelled a single population of SRIF binding sites in RDCM membranes and mouse fibroblast (Ltk–) cells stably expressing the human recombinant sst2 receptor. There was a significant correlation between the affinity estimates of a range of SRIF analogues at inhibiting [125I]-BIM-23027 binding in RDCM membranes and binding to the recombinant sst2 receptor in Ltk– cells, suggesting that the sites labelled by [125I]-BIM-23027 in RDCM are similar to the sst2 receptor. GTPγS (100 μM) decreased [125I]-BIM-23027 binding in RDCM by 60%. The results from these studies demonstrate that [125I]-Tyr11-SRIF-14 labels a heterogeneous population of high affinity SRIF binding sites in RDCM membranes. The majority of these sites are insensitive to GTPγS and display negligible affinity for the cyclic hexapeptides, BIM-23027 and seglitide. The remaining high affinity binding sites can be selectively labelled with [125I]-BIM-23027, are sensitive to GTPγS and show similar characteristics to the recombinant sst2 receptor which appears to mediate the antisecretory effects of SRIF in the mucosa (McKeen ES, Feniuk W, Humphrey PPA (1995) Naunyn-Schmiedeberg‘s Arch Pharmacol 352:402–411).
    Type of Medium: Electronic Resource
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