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  • Congenital cataract  (2)
  • Toxaphene  (2)
  • Type I hepatic transport of cationic drugs  (2)
  • 1995-1999  (6)
Document type
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  • 1995-1999  (6)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 354 (1996), S. 320-326 
    ISSN: 1432-1912
    Keywords: Rat liver ; Transport of organic cations ; OCT1 ; Type I hepatic transport of cationic drugs ; 1-Methyl-4-phenylpyridinium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The kidneys and the liver are the principal organs for the inactivation of circulating organic cations. Recently, an organic cation transporter (OCT1) has been cloned from rat kidney. In order to answer the question whether OCT1 is involved also in hepatic uptake of organic cations, the pharmacological characteristics of organic cation transport in hepatocytes were compared to the characteristics of transiently expressed OCT1. Primary cultures of rat hepatocytes avidly accumulated the small organic cation 3H-1-methyl-4-phenylpyridinium (3H-MPP+). At equilibrium, the hepatocytes accumulated 3H-MPP+ 56-fold. Initial rates of specific 3H-MPP+ transport in hepatocytes were saturable. The half-saturating concentration was 13 μmol/l. 3H-MPP+ transport was sensitive to quinine (Ki = 0.79 μmol/l) and cyanine863 (Ki = 0.097 µmol/l). Quinine and cyanine863 are known inhibitors of type I hepatic transport of cationic drugs and of renal excretion of organic cations, respectively. To compare the functional characteristics of 3H-MPP+ transport in hepatocytes with those of OCT1, OCT1 has been heterologously expressed and characterized in a mammalian cell line (293 cells). Initial rates of 3H-MPP+ transport were saturable, the Km being 13 μmol/l. The rank order of inhibitory potencies of various inhibitors was almost identical in hepatocytes and 293 cells transiently transfected with OCT1. There was a positive correlation between the Ki's for the inhibition of 3H-MPP+ transport in isolated hepatocytes and transfected 293 cells (r = 0.85; P〈0.01; n = 8). The results indicate that OCT1 is functionally expressed not only in the kidney but also in hepatocytes where it is responsible for the transport of small organic cations which, in the past, have been classified as type I substrates.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 354 (1996), S. 320-326 
    ISSN: 1432-1912
    Keywords: Key words Rat liver ; Transport of organic cations ; OCT1 ; Type I hepatic transport of cationic drugs ; 1-Methyl-4-phenylpyridinium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The kidneys and the liver are the principal organs for the inactivation of circulating organic cations. Recently, an organic cation transporter (OCT1) has been cloned from rat kidney. In order to answer the question whether OCT1 is involved also in hepatic uptake of organic cations, the pharmacological characteristics of organic cation transport in hepatocytes were compared to the characteristics of transiently expressed OCT1. Primary cultures of rat hepatocytes avidly accumulated the small organic cation 3H-1-methyl-4-phenylpyridinium (3H-MPP+). At equilibrium, the hepatocytes accumulated 3H-MPP+ 56-fold. Initial rates of specific 3H-MPP+ transport in hepatocytes were saturable. The half-saturating concentration was 13 μmol/l. 3H-MPP+ transport was sensitive to quinine (Ki = 0.79 μmol/l) and cyanine863 (Ki = 0.097 μmol/l). Quinine and cyanine863 are known inhibitors of type I hepatic transport of cationic drugs and of renal excretion of organic cations, respectively. To compare the functional characteristics of 3H-MPP+ transport in hepatocytes with those of OCT1, OCT1 has been heterologously expressed and characterized in a mammalian cell line (293 cells). Initial rates of 3H-MPP+ transport were saturable, the Km being 13 μmol/l. The rank order of inhibitory potencies of various inhibitors was almost identical in hepatocytes and 293 cells transiently transfected with OCT1. There was a positive correlation between the Ki’s for the inhibition of 3H-MPP+ transport in isolated hepatocytes and transfected 293 cells (r = 0.85; P〈0.01; n = 8). The results indicate that OCT1 is functionally expressed not only in the kidney but also in hepatocytes where it is responsible for the transport of small organic cations which, in the past, have been classified as type I substrates.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 154 (1995), S. 389-391 
    ISSN: 1432-1076
    Keywords: Sorbitol dehydrogenase ; Lens ; Congenital cataract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Lens sorbitol dehydrogenase activity was assayed in patients with congenital cataracts, senile cataracts, without cataracts and in one fetal lens. In patients with congenital cataracts we did not observe any abnormality of galactose and sorbitol metabolising enzymes in erythrocytes. In one of these patients with inexplicable congenital cataracts lens sorbitol dehydrogenase deficiency was found. Conclusion Determination of galactose metabolising enzymes, sorbitol dehydrogenase and polyols in lenses may help in understanding the mechanism of formation of inexplicable congenital cataracts.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 154 (1995), S. 389-391 
    ISSN: 1432-1076
    Keywords: Key words Sorbitol dehydrogenase ; Lens ; Congenital cataract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Lens sorbitol dehydrogenase activity was assayed in patients with congenital cataracts, senile cataracts, without cataracts and in one fetal lens. In patients with congenital cataracts we did not observe any abnormality of galactose and sorbitol metabolising enzymes in erythrocytes. In one of these patients with inexplicable congenital cataracts lens sorbitol dehydrogenase deficiency was found. Conclusion Determination of galactose metabolising enzymes, sorbitol dehydrogenase and polyols in lenses may help in understanding the mechanism of formation of inexplicable congenital cataracts.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1612-1112
    Keywords: Gas chromatography-mass spectrometry ; Electron-capture negative ionization ; Toxaphene ; Seal blubber samples ; Antarctic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatography and electron-capture, negative-ionization, mass spectrometry (GC-ECNI-MS) in combination with a non-polar stationary phase (CP-Sil 2) was applied to study the composition of residues of the multicomponent toxaphene mixture in seal blubber from the Antarctic. In samples of the five Antarctic seal species eleven compounds of technical toxaphene (CTTs) were detected and six of them quantified by application of single standard compounds. Five abundant CTTs in seal blubber were included in the “Parlar 22 components standard” (commercially available) and one further was isolated and quantified for the first time. Finally, high levels of toxaphene were determined in Weddell seals and crabeaters confirming that toxaphene is a major organochlorine pollutant in the Antarctic.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Chiral stationary phases ; Enantioseparation ; Toxaphene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the enantiomers of the compounds of technical toxaphene (CTTs) on heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin (β-TBDM) has been studied by gas chromatography with electron-capture detection (GC-ECD). Enantiomers of eight of the nine CTTs under investigation were separated on this chiral stationary phase. Separations of the enantioners of CTTs have hitherto been achieved ontert-butyldimethylsilylated β-cyclodextrin (β-BSCD). The chiral resolution values and separation factors of the CTTs on β-TBDM have been compared with those obtained on β-BSCD. Although several components coeluted, enantioselective determination of three CTTs was possible in an extract of seal blubber. For each CTT the first-eluting enantiomer was enantioenriched. Enantioselective accumulation of2-endo, 3-exo,5-endo,6-exo,-8,8,9,10-octachlorobornane (B8-1412) in biota has been established for the first time.
    Type of Medium: Electronic Resource
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