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  • 1
    Electronic Resource
    Electronic Resource
    Selective agonists of retinoic acid receptors: comparative toxicokinetics and embryonic exposure (2000)
    Springer
    Archives of toxicology 73 (2000), S. 547-556 
    Details
    ISSN: 1432-0738
    Keywords: Key words Selective retinoids ; Toxicokinetics ; Embryonic exposure ; Area under the time vs concentration curve (AUC) ; Retinoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Three biologically active synthetic retinoids were investigated that bind selectively to retinoic acid receptors RARs (α, β and γ). The retinoids were previously demonstrated to have different teratogenic effects in the mouse in terms of potency and regioselectivity. The teratogenic potency rank order (α 〉β 〉γ) was found to be more or less compatible with the receptor binding affinities and transactivation potencies of the retinoid ligands to their respective receptors. The RARα agonist (Am580; CD336) induced a wide spectrum of malformations; CD2019 (RARβ agonist) and especially CD437 (RARγ agonist) produced more restricted defects. In the current study we tried to address whether the differences in teratogenic effects are solely related to binding affinity and transactivation differences or also due to differences in embryonic exposure. Therefore, transplacental kinetics of the ligands were assessed following administration of a single oral dose of 15 mg/kg of either retinoid given to NMRI mice on day 11 of gestation. Am580 was rapidly transferred to the embryo resulting in the highest embryonic exposure [embryo to maternal plasma area under the time vs concentration curve (AUC)0–24 h ratio (E/M) was 1.7], in accordance with its highest teratogenic potency. The low placental transfer of CD2019 (E/M of 0.3) was compatible with its lower teratogenic potential. Of major interest was the finding that the CD437, though being least teratogenic, exhibited considerable embryonic exposure (E/M of 0.6). These findings suggest that both the embryonic exposure and receptor binding transactivation selectivity are crucial determinants of the teratogenicity of these retinoid ligands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050007
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  • 2
    Electronic Resource
    Electronic Resource
    Production of oxytetracycline by immobilized Streptomyces rimosus cells in calcium alginate gels (1994)
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 14 (1994), S. 303-309 
    Details
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Streptomyces rimosus Pfizer 18234-2 cells were immobilized in calcium alginate and used for the production of oxytetracycline. The influence of the incubation period, alginate concentration and storage in CaCl2 were investigated. From the results of the repeated batch fermentations of the shake flasks, a good level of antibiotic was maintained for a period of about 28 days using 4% calcium alginate. The cell leakage and cell concentration inside the beads were affected by the alginate concentration and storage in CaCl2 solution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/abio.370140316
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Production of oxytetracycline and rifamycins B and SV with cells immobilized on glass wool (1994)
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 14 (1994), S. 67-74 
    Details
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The antibiotic producing microorganisms Streptomyces rimosus PFIZER 18234-2 and Amycolatopsis mediterranei CBS 42575 were immobilized in glass wool for the production of oxytetracycline and rifamycins B and SV. The growth of the immobilized cells was dependent on the type of the microorganism and on the amount of glass wool as well. After 5 exchanges of the medium, 530 mg O.T.C., 2138 mg rifamycin B and 8672 mg rifamycin SV were maintained. The periodic batch culture was continued for 20 days.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/abio.370140112
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  • 4
    Electronic Resource
    Electronic Resource
    Optimization of some culture parameters and properties of β-glucosidase and β-xylosidase from Penicillium funiculosum NRRL - 13033 (1989)
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 9 (1989), S. 347-353 
    Details
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Penicillium funiculosum NRRL 13033 produced β-glucosidase and β-xylosidase activities when grown on wheat straw. The addition of some inducers (individually or in combination) to the fermentation medium were tested for the production of both enzymes. The relation of mycelial bound enzyme to cell free enzyme was studied during incubation period of fermentation. The optimum activity of β-glucosidase and β-xylosidase were found to be in the pH 4.5 using phosphate-citrate buffer at 50°C for 60 min and at 55°C for 40 min respectively. β-Glucosidase lost about 40% of its original activity by heating to 65°C for 60 min, while, β-xylosidase activity was found to be nearly stable with the same treatment. Both enzyme activities were greatly inhibited when 1.0% (w/v) of xylose and glucose were added to the assay mixture.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/abio.370090408
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Production of rifamycin B and SV by free and immobilized cells of Amycolatopsis mediterranei (1995)
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 15 (1995), S. 241-248 
    Details
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of growth conditions (incubation time, inoculum size, initial pH value) and some nutrient concentrations on the growth and rifamycin B and SV production by free and immobilized cells of Amycolatopsis mediterranei CBS 42 575 was studied. In alginate beads, the immobilized cells behaved like the free cells, but a pronounced difference was observed in antibiotic production and cell growth. The rifamycin production by the immobilized cells was higher than that obtained by the free cells. The immobilized cells were also reused repeatedly for six batch cultivations with a fresh medium charged into flasks at the beginning of each batch. It was found that the immobilized cells were stable, and the rifamycin yield was almost constant during the first three batches and then decreased.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/abio.370150215
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    Paper (German National Licenses)
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