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  • 1995-1999  (6)
  • Polymer and Materials Science  (3)
  • glycation  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Aminoguanidine does not inhibit the initial phase of experimental diabetic retinopathy in rats (1995)
    Springer
    Diabetologia 38 (1995), S. 269-273 
    Details
    ISSN: 1432-0428
    Keywords: Key words Diabetic retinopathy ; rat model ; aminoguanidine ; glycation ; retinal basement membrane.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have previously shown that long-term administration of aminoguanidine, an inhibitor of advanced glycosylation product formation, reduces the extent of experimental diabetic retinopathy in the rat by 85 %. In order to determine whether the residual retinopathy that developed despite aminoguanidine was attributable to advanced glycation endproduct formation, a time-course study was performed in three different groups of male Wistar rats: non-diabetic controls (NC), streptozotocin-diabetic controls (DC) and streptozotocin-diabetic rats treated with aminoguanidine HCL, 50 mg/100 ml drinking water (D-AG). Eyes were obtained at 24, 32, 44 and 56 weeks of diabetes/treatment duration and morphologic evaluation was done on retinal digest preparations. At 56 weeks, retinal basement membrane thickness was additionally measured. After 24 weeks of diabetes, the number of acellular capillaries was significantly elevated in DC (44.6 ± 5.7/mm2 of retinal area, NC 19.6 ± 4.9; p 〈 0.001) and increased continuously over time (DC 56 weeks 87.4 ± 15.1; p 〈 0.001 vs DC 24 weeks). In contrast, acellular capillaries in D-AG increased over the first 24 weeks and then remained constant for the rest of the study (D-AG 24 weeks 35.7 ± 5.18; p 〈 0.01 vs NC 24 weeks and NS vs DC 24 weeks; D-AG 56 weeks 42.0 ± 6.20; p NS vs D-AG 24 weeks). Diabetes-associated pericyte loss (DC 24 weeks 2310 ± 170/mm2 of capillary area; NC 24 weeks 3120 ± 190; p 〈 0.001; DC 56 weeks 1570 ± 230; NC 56 weeks 2960 ± 50; p 〈 0.001) was significantly prevented by aminoguanidine after diabetic-like changes over the initial 24 weeks (D-AG 24 weeks 2450 ± 75; p NS vs DC 24 weeks; D-AG 56 weeks 2350 ± 90; p 〈 0.001 vs DC 56 weeks). At 56 weeks, aminoguanidine treatment was associated with a 67.4 % reduction in retinal basement membrane thickening. This time-course study demonstrates that aminoguanidine prevents the progression of experimental diabetic retinopathy, and suggests that non AG-inhibitable mechanisms are involved in the initial phase of diabetic retinopathy. [Diabetologia (1995) 38: 269–273]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400629
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Aminoguanidine does not inhibit the initial phase of experimental diabetic retinopathy in rats (1995)
    Springer
    Diabetologia 38 (1995), S. 269-273 
    Details
    ISSN: 1432-0428
    Keywords: Diabetic retinopathy ; rat model ; aminoguanidine ; glycation ; retinal basement membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have previously shown that long-term administration of aminoguanidine, an inhibitor of advanced glycosylation product formation, reduces the extent of experimental diabetic retinopathy in the rat by 85%. In order to determine whether the residual retinopathy that developed despite aminoguanidine was attributable to advanced glycation endproduct formation, a time-course study was performed in three different groups of male Wistar rats: non-diabetic controls (NC), streptozotocin-diabetic controls (DC) and streptozotocin-diabetic rats treated with aminoguanidine HCL, 50 mg/100 ml drinking water (D-AG). Eyes were obtained at 24, 32, 44 and 56 weeks of diabetes/treatment duration and morphologic evaluation was done on retinal digest preparations. At 56 weeks, retinal basement membrane thickness was additionally measured. After 24 weeks of diabetes, the number of acellular capillaries was significantly elevated in DC (44.6±5.7/mm2 of retinal area, NC 19.6±4.9; p〈0.001) and increased continuously over time (DC 56 weeks 87.4±15.1; p〈0.001 vs DC 24 weeks). In contrast, acellular capillaries in D-AG increased over the first 24 weeks and then remained constant for the rest of the study (D-AG 24 weeks 35.7±5.18; p〈0.01 vs NC 24 weeks and NS vs DC 24 weeks; D-AG 56 weeks 42.0±6.20; p NS vs D-AG 24 weeks). Diabetes-associated pericyte loss (DC 24 weeks 2310±170/mm2 of capillary area; NC 24 weeks 3120±190; p〈0.001; DC 56 weeks 1570±230; NC 56 weeks 2960±50; p〈0.001) was significantly prevented by aminoguanidine after diabetic-like changes over the initial 24 weeks (D-AG 24 weeks 2450±75; p NS vs DC 24 weeks; D-AG 56 weeks 2350±90; p〈0.001 vs DC 56 weeks). At 56 weeks, aminoguanidine treatment was associated with a 67.4% reduction in retinal basement membrane thickening. This time-course study demonstrates that aminoguanidine prevents the progression of experimental diabetic retinopathy, and suggests that non AG-inhibitable mechanisms are involved in the initial phase of diabetic retinopathy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400629
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Effects of radiation on mechanical properties of polybutadiene/polystyrene blends (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 85-94 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends containing 3 wt % low molecular weight polybutadiene (PB) in a polystyrene (PS) matrix were prepared via a precipitation technique that yielded spherical, submicron pools of PB. Tensile specimens made from these blends were then irradiated with high energy electrons in air at dose levels from 0 to 70 Mrads. The blends, which previously showed high levels of toughness approaching that of high impact PS, lost all enhanced toughness when irradiated above 10 Mrads. Analysis of pure PS specimens irradiated over the dose range from 0 to 45 Mrads showed no appreciable dependence of mechanical behavior on dose level. Molecular weight studies of the polybutadiene demonstrated only a very modest increase in molecular weight in the dose range studied here; therefore, reduced mobility of the PB in the blends was not the reason for the dramatic drop in toughness with radiation dose. It was concluded that radiation-induced scission of the PS near the surface of the blends resulted in a significant local reduction in molecular weight. This degraded layer led to premature craze failure and hence a low level of toughness. It was demonstrated that the absence of oxygen during the irradiation process or the removal of the scissioned surface layer via mechanical abrasion resulted in a recovery of toughness. © 1995 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070580109
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The stability of poly(ether urethane)/polydimethylsiloxane interpenetrating polymer networks (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 733-740 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Interpenetrating polymer networks (IPNs) are a special type of polymer blend consisting of two polymer networks synthesized and/or cross-linked independently within each other. One potential approach for the preparation of composite materials from polymers having desirable physical characteristics obtained by modifying their surfaces with physiologically acceptable polymers involves IPN technology. An IPN based on a poly(ether urethane) and polydimethylsiloxane has been synthesized and charaterized using optical microscopy, dynamic mechanical analysis, and scanning electron microscopy. The stability of poly(ether urethane)/polydimethylsiloxane composites were studied in hydroxyl radical aqueous solutions over 30 weeks. The data suggest that these composites have good potential for biomedical applications. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070550509
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  • 5
    Electronic Resource
    Electronic Resource
    Cyclopolymerization studies of diallyl-and tetraallylpiperazinium salts (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 1077-1085 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The quaternary ammonium salt 1,1-diallyl-4-formylpiperazinium chloride (7) was synthesized in good yields. The monomer (7) on cyclopolymerization in the presence of ammonium persulfate in water solution at 90°C afforded water-soluble polymer (8) having excellent rheological properties. The synthesis of the polymer (8) paves the way for the preparation of a novel class of polymers: dicationic polyelectrolytes (9) and cationic polymer (10) with a basic nitrogen as well as a quaternary nitrogen. Effects of monomer, initiator, and additives concentration were studied. Cyclopolymerization of (7) with 1,1,4,4-tetraallylpiperazinium dichloride (12) gave ion-exchange resins with excellent swelling coefficients. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Glycation of human lens proteins from diabetic and (nondiabetic) senile cataract patients (1995)
    Springer
    Glycoconjugate journal 12 (1995), S. 618-621 
    Details
    ISSN: 1573-4986
    Keywords: glycation ; lens proteins ; diabetes ; ageing ; cataract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Glycation (nonenzymatic glycosylation) in the human lens (cortex and nucleus) in senile (nondiabetic) and diabetic cataracts was studied by measuring the extent of early and late glycation products, the content of free ε-amino groups and the formation of disulfide bonds in the soluble lens proteins. There was a significant (p〈0.001) increase in early and late glycation in the lens nucleus compared to the cortex in both the senile and diabetic groups. Overall these changes were much larger in the diabetic group. The concentration of free ε-amino groups was decreased in the senile nucleus as well as in the diabetic nucleus when compared with the senile and diabetic cortex (p〈0.001). Disulfide bond content was in the order of diabetic nucleus 〉 diabetic cortex 〉 senile nucleus 〉 senile cortex. Glycation of the lens proteins is a generalized feature which is enhanced in the diabetic lens compared to senile lens proteins and is associated with a decrease in free ε-amino groups and an increase in disulfide bonds formation in the lens proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00731255
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