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  • 1
    Electronic Resource
    Electronic Resource
    Functional Characterization of Mutant Strains of the Cyanobacterium Synechocystis sp. PCC 6803 Lacking Short Domains within the Large, Lumen-Exposed Loop of the Chlorophyll Protein CP47 in Photosystem II (1994)
    s.l. : American Chemical Society
    Biochemistry 33 (1994), S. 12063-12071 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00206a008
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  • 2
    Electronic Resource
    Electronic Resource
    Involvement of the CP47 Protein in Stabilization and Photoactivation of a Functional Water-Oxidizing Complex in the Cyanobacterium Synechocystis sp. PCC 6803 (1995)
    s.l. : American Chemical Society
    Biochemistry 34 (1995), S. 6847-6856 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00020a031
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  • 3
    Electronic Resource
    Electronic Resource
    The influence of leflunomide on cell cycle, IL-2-receptor (Il-2-R) and its gene expression (1995)
    Springer
    Inflammation research 44 (1995), S. 143-143 
    Details
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01782026
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  • 4
    Electronic Resource
    Electronic Resource
    Prostaglandin-Interaktion in der menschlichen Leber (1989)
    Springer
    Journal of molecular medicine 67 (1989), S. 1229-1235 
    Details
    ISSN: 1432-1440
    Keywords: PGE1, PGE2, PGI2, Iloprost ; cAMP ; Normal liver ; Hepatocellular cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The binding of prostaglandin (PG) E1 and Iloprost, a chemically stable PGI2-analogue, to purified plasma cell membranes (LPZM) from liver tissue samples obtained at surgery revealed heterogeneity of the binding sites identifying high and low affinity subpopulations. In contrast to these findings only high affinity binding sites were characterized for PGE2. Displacement studies exhibited the highest competition for the PGE1-sites by PGE1 and subsequently by PGE2, Iloprost, PGD2 and PGF2 α. The binding of PGE2 to the hepatic receptor could be best displaced by PGE2 and subsequently by PGE1 and Iloprost, PGD2 and PGF2 α. In addition, PGE1, PGE2 and Iloprost enhanced cAMP-production dose-dependently over baseline. Clinical studies revealed a remarkably lower binding capacity for PGE1 in hepatocellular cancer tissue than in noral liver parenchyma. The different binding behaviour of PGE1 (Iloprost) and PGE2 for the first time provides evidence that PGE1 and PGI2 like at platelet membranes occupate the same receptor also at human LPZM. Since a reasonable number of binding sites for these substances and an enhanced cAMP-production were shown in the liver, the study indicates a regulatory role of PGs in hepatic function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01745294
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  • 5
    Electronic Resource
    Electronic Resource
    Editorial note (1984)
    Springer
    Archives of toxicology 55 (1984), S. 149-149 
    Details
    ISSN: 1432-0738
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316118
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  • 6
    Electronic Resource
    Electronic Resource
    Chromium (VI) reducing capacity of ascorbic acid and of human plasma in vitro (1992)
    Springer
    Archives of toxicology 66 (1992), S. 45-50 
    Details
    ISSN: 1432-0738
    Keywords: Chromium(VI) ; Ascorbic acid ; Human plasma ; Reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the metabolism of chromium(VI) its reduction in human plasma is of importance; an extracellular reduction of Cr(VI) is regarded as a detoxification step. Ascorbic acid has been suggested to represent the majority of the Cr(VI)-reducing capacity of human plasma. Therefore the kinetics of the reaction of Cr(VI) with ascorbic acid, at biologically realistic concentrations were studied. Ascorbic acid, in 0.2 M HEPES buffer and at concentrations ranging from 14.2 to 113.6 nmol ml−1 (2.5–20.0 μg ml−1), was mixed with Cr(VI) (0.4–1.5 nmol ml−1) and incubated at pH 7.4 and 37° C. In addition, chromate solutions at different concentrations [1.5–100 nmol ml−1 Cr(VI)], were incubated at 37° C with freshly drawn blood. From these incubates, ascorbic acid and its oxidized form, dehydroascorbic acid, were simultaneously analyzed by HPLC and post-column derivatization. Chromate was determined by flow injection analysis. The reaction kinetics of ascorbic acid in HEPES buffer with Cr(VI) is of pseudofirst order at higher concentrations, whilst apparently at lower concentrations kinetics are consistent with an autocatalyzed reaction. Results obtained after spiking human plasma are similar. However, when Cr(VI) was reacted with human plasma, no changes in the intrinsic contents of ascorbic acid of the plasma samples occurred. Also, comparing different plasma samples the intrinsic plasma contents of ascorbic acid and the reduction capacities for Cr(VI) [ranging between 0.48 and 0.63 nmol ml−1 Cr(VI) to be reduced] did not correlate. This shows that the reduction of Cr(VI) in native human plasma is complex and is not only determined by the plasma ascorbic acid levels. This is in contrast to the situation in lung lavage fluids (Suzuki 1988; Suzuki and Fukuda 1990) where the concentrations of ascorbic acid are much higher than in blood.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02307269
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  • 7
    Electronic Resource
    Electronic Resource
    Influence of polymorphisms of GSTM1 and GSTT1 for risk of renal cell cancer in workers with long-term high occupational exposure to trichloroethene (1997)
    Springer
    Archives of toxicology 71 (1997), S. 596-599 
    Details
    ISSN: 1432-0738
    Keywords: Key words Trichloroethene ; Renal cell cancer ; GSTM1 ; GSTT1 ; Glutathione transferases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Suspected nephrocarcinogenic effects of trichloroethene (TRI) in humans are attributed to metabolites derived from the glutathione transferase (GST) pathway. The influence of polymorphisms of GSTM1 and GSTT1 isoenzymes on the risk of renal cell cancer in subjects having been exposed to high levels of TRI over many years was investigated. GSTM1 and GSTT1 genotypes were determined by internal standard controlled polymerase chain reaction. Fourty-five cases with histologically verified renal cell cancer and a history of long-term occupational exposure to high concentrations of TRI were studied. A reference group consisted of 48 workers from the same geographical region with similar histories of occupational exposures to TRI but not suffering from any cancer. Among the 45 renal cell cancer patients, 27 carried at least one functional GSTM1 gene (GSTM1+) and 18 at least one functional GSTT1 gene (GSTT1+). Among the 48 reference workers, 17 were GSTM1+ and 31 were GSTT1+. Odds ratios for renal cell cancer were 2.7 for GSTM1+ individuals (95% CI, 1.18–6.33; P 〈 0.02) and 4.2 for GSTT1+ individuals (95% CI, 1.16–14.91; P 〈 0.05), respectively. The data support the present concept of the nephrocarcinogenicity of TRI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050432
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  • 8
    Electronic Resource
    Electronic Resource
    Haemoglobin adducts of acrylonitrile and ethylene oxide in acrylonitrile workers, dependent on polymorphisms of the glutathione transferases GSTT1 and GSTM1 (1999)
    Springer
    Archives of toxicology 73 (1999), S. 197-202 
    Details
    ISSN: 1432-0738
    Keywords: Key words Acrylonitrile ; Ethylene oxide ; Haemoglobin adducts ; Glutathione transferase (GST) polymorphisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fifty-nine persons with industrial handling of low levels of acrylonitrile (AN) were studied. As part of a medical surveillance programme an extended haemoglobin adduct monitoring [N-(cyanoethyl)valine, CEV; N-(methyl)valine, MV; N-(hydroxyethyl)valine, HEV] was performed. Moreover, the genetic states of the polymorphic glutathione transferases GSTM1 and GSTT1 were assayed by polymerase chain reaction (PCR). Repetitive analyses of CEV and MV in subsequent years resulted in comparable values (means, 59.8 and 70.3 μg CEV/l blood; 6.7 and 6.7 μg MV/l blood). Hence, the industrial AN exposures were well below current official standards. Monitoring the haemoglobin adduct CEV appears as a suitable means of biomonitoring and medical surveillance under such exposure conditions. There was also no apparent correlation between the CEV and HEV or CEV and MV adduct levels. The MV and HEV values observed represented background levels, which apparently are not related to any occupational chemical exposure. There was no consistent effect of the genetic GSTM1 or GSTT1 state on CEV adduct levels induced by acrylonitrile exposure. Therefore, neither GSTM1 nor GSTT1 appears as a major AN metabolizing isoenzyme in humans. The low and physiological background levels of MV were also not influenced by the genetic GSTM1 state, but the MV adduct levels tended to be higher in GSTT1− individuals compared to GSTT1+ persons. With respect to the background levels of HEV adducts observed, there was no major influence of the GSTM1 state, but GST− individuals displayed adduct levels that were about 1/3 higher than those of GSTT1+ individuals. The coincidence with known differences in rates of background sister chromatid exchange between GSTT1− and GSTT1+ persons suggests that the lower ethylene oxide (EO) detoxification rate in GSTT1− persons, indicated by elevated blood protein hydroxyethyl adduct levels, leads to an increased genotoxic effect of the physiological EO background.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050606
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  • 9
    Electronic Resource
    Electronic Resource
    Toxicokinetics of p-tert-octylphenol in female DA/Han rats after single i.v. and oral application (1999)
    Springer
    Archives of toxicology 73 (1999), S. 217-222 
    Details
    ISSN: 1432-0738
    Keywords: Key wordsp-tert-Octylphenol ; Nonylphenol ; Environmental oestrogens ; Toxicokinetics ; Enterohepatic circulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Female DA/Han rats were administered p-tert-octylphenol [OP; p-(1,1,3,3-tetramethylbutyl)-phenol], either intravenously (5 mg/kg body wt.) or orally by gavage (50 or 200 mg/kg body wt.). After i.v. administration the blood concentration-time curve of OP was fitted to a tri-exponential model, resulting in a final half-life (γ-phase) of 36.1 h. This contrasts to much more rapid eliminations previously reported in male Wistar rats. The oral bioavailability of 50 mg/kg OP was 12.3% and of 200 mg/kg 8.4%. The higher dose (200 mg/kg) was absorbed slower than the smaller dose, probably due to low solubility of OP in aqueous media. Maximal OP blood levels in female DA/Han rats receiving 50 and 200 mg OP/kg body wt. were 4.5 and 3 times higher than previously reported in male Wistar rats. The blood concentration-time curves after oral administration of OP to female DA/Han rats revealed pronounced interindividual differences, indicating extensive enterohepatic circulation of OP in this rat strain. In contrast to male Wistar rats, after application of high doses of OP to female DA/Han rats the compound was not completely eliminated within 48 h; under these conditions some bioaccumulation might therefore occur. The experimental toxicokinetics of OP appears as a relevant subject to be integrated into extrapolation of toxicological data, from in vitro to in vivo, and into systems of risk assessment of endocrine modulating activity which are currently being developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050609
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  • 10
    Electronic Resource
    Electronic Resource
    New scientific arguments for regulation of ethylene oxide residues in skin-care products (1994)
    Springer
    Archives of toxicology 68 (1994), S. 401-405 
    Details
    ISSN: 1432-0738
    Keywords: Key words: Ethylene oxide – Polyglycol ethers – Skin-care products – Risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Ethylene oxide (EO) occurs as a contaminant of skin-care products because current commercial preparations of polyglycol ethers may contain ethylene oxide monomer residues, up to the order of 1 ppm. Using current regulatory worst-case assumptions, the presence of EO in skin-care products might lead to a maximal human daily external ethylene oxide dose of about 2.8 μg, and a consecutive maximal daily absorbed dose of 0.39 μg. Two methods of toxicokinetic analysis have been used to compare this possible EO load by use of skin-care products with the inevitable load of EO which is produced endogenously in the organism. On the basis of a previous assessment of the endogenous production of ethylene and ethylene oxide (Filser et al. 1992) it is inferred that the absorbed EO dose of 0.39 μg is about 1/30 of the unavoidable human endogenous load by endogenous EO. Alternatively, for a second calculation molecular dosimetry data have been used which were based on experimental quantification of the hydroxyethyl adduct of EO to the N-terminal valine of hemoglobin (HOEtVal) in rats. If the worst-case assumptions for human EO absorption from skin-care products are transferred to the rat species, the associated internal EO doses are about 1/110 of the internal EO doses which were calculated from the background HOEtVal concentrations observed in untreated animals. The divergence between both lines of calculation is mainly due to differences in HOEtVal background concentrations between man and rat. It is concluded that the additional internal body burden of EO associated with the use of current skin-care products, even under a series of worst-case assumptions, is neglegible compared to the physiological and unavoidable internal EO burden of the organism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050089
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