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  • Biochemistry and Biotechnology  (2)
  • Fluorochrome-labeled capillaries  (2)
  • Liesegang rings  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Pulmonary uptake of bupivacaine in isolated perfused rat lung (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 99-106 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Lung perfusion ; Bupivacaine ; Fluorochrome-labeled capillaries ; First-pass retention ; Inulin ; Tritium-labeled water
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The ability of rat lung to remove the local anaesthetic drug bupivacaine from the blood was studied in isolated organs which were perfused either in an open (single-pass mode) or in a closed system (recirculating medium). Isolated perfused rat lungs exhibited a very low capacity to metabolize bupivacaine within 3 h during which the drug circulated continuously through the organ. The clearance values differed only by 0.2 ml/min from the control parameters in sham perfusions. The calculated extraction ratio was 0.2% and the elimination half-life was about 210 min. The volume of distribution of bupivacaine was 133 ml which remarkably surmounted the reference values obtained for sham perfusions. The distribution of bupivacaine into the pulmonary tissue was investigated applying the multiple indicator dilution technique to isolated lungs perfused in the single-pass mode. The mean elimination time of model compounds for distribution into the intravascular space, 14C-inulin, and the total water space, 3H-water, were 68 and 75 s at a flow rate of 6 ml/min. The volume of distribution was 5.9 ml for inulin and 6.5 ml for water. The mean transit time for concomitantly injected bupivacaine was 221 s and the volume of distribution was 14.4 ml. The respective parameters of sham perfusions performed without an isolated organ were substantially lower, i.e. mean elimination time 50, 50 and 61 s and distribution volume 4.9, 5.0 and 6.1 ml for inulin, water and bupivacaine. The volume of distribution during single-pass contact of bupivacaine to lung was not substantially influenced by an increase of the flow rate from 6 to 9 and 12 ml/min whereas the mean transit time dropped from 221 to 121 and 108 s, respectively. These results support the assumption that bupivacaine is extensively retained by the pulmonary tissue and that elimination of bupivacaine by metabolism can be neglegted for lung. The hemodynamic parameters of bronchiolar perfusion in the artificially perfused lung were determined using two fluorochrome-labeled macromolecular proteins, i.e. fluorescein-isothiocyanate (FITC)- and lissamine-rhodamine-B 200 (RB 200)-labeled globulin. After 10 min of perfusion at a flow rate of 12 ml/min in the closed system an area of 10.8070 of the peribronchiolar tissue area contained the dye-label FITC. A very similar index (10.1%) of dye-coloured capillaries was obtained when the lungs of anaesthetized rats were examined 10 min after intravenous injection of the fluorochrome into the pulmonary artery in vivo. In isolated perfused rat lungs receiving both FITC and RB 200 59.5% of FITC-labeled capillaries were reached by the second fluorochrome within 2 s. This fraction accounted for 93.3% after 10 s of circulation time. This proves that isolated rat lungs were well perfused in vitro.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00169070
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  • 2
    Digitale Medien
    Digitale Medien
    Morphological instabilities in pattern formation by precipitation and crystallization processes (1996)
    Springer
    International journal of earth sciences 85 (1996), S. 19-28 
    Details
    ISSN: 1437-3262
    Schlagwort(e): Anastomoses ; Crystal zoning ; Snow bands ; Liesegang rings ; Ostwald ripening ; Self organization ; Siderite ; Supersaturation theory ; Zebra rock
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract Morphological instabilities in periodic patterns occurring both in precipitation and crystallization processes (Liesegang rings and crystal zoning) are investigated and compared with similar patterns in geological samples (zebra rocks and mud bands in snow sediments). In classical Liesegang systems, undisturbed parallel or concentric precipitation bands are emanated from even or concentric diffusion sources in homogeneous diffusion matrices of gelatine or other gels. In the case of superposing diffusion sources, sources with undulatory curvatures or local diffusion barriers there may occur several types of instabilities within the sequence of regular patterns: (a) gaps within the bands forming radial alleys free of precipitate, (b) transition from broken bands to speckled patterns and (c) apparent branching of bands linked together by so-called anastomoses. Calculations with a competitive particle growth (CPG) model show that lateral instabilities in Liesegang bands (gaps and radial alleys of gaps) are the result of Ostwald ripening effects taking place after precipitation. Apparent branching of bands or formation of anastomoses can be simulated with a prenucleation model according to Ostwald's supersaturation theory. Similar irregularities can be observed in zebra rocks (e.g. banded siderite) whose bandings are commonly explained by sequential sedimentation processes. A very different mechanism is assumed to be responsible for the origin of mud bands in snow sediments. An initially homogeneous distribution of intrinsic mud in snow sediments can be arranged into parallel bands according to a crystal zoning mechanism which is based on repeated thawing and freezing of the snow sediment due to the daily alternation of sun and darkness.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192056
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Pulmonary uptake of bupivacaine in isolated perfused rat lung (1994)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1994), S. 99-106 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Key words Lung perfusion ; Bupivacaine ; Fluorochrome-labeled capillaries ; First-pass retention ; Inulin ; Tritium-labeled water
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The ability of rat lung to remove the local anaesthetic drug bupivacaine from the blood was studied in isolated organs which were perfused either in an open (single-pass mode) or in a closed system (recirculating medium). Isolated perfused rat lungs exhibited a very low capacity to metabolize bupivacaine within 3 h during which the drug circulated continuously through the organ. The clearance values differed only by 0.2 ml/min from the control parameters in sham perfusions. The calculated extraction ratio was 0.2% and the elimination half-life was about 210 min. The volume of distribution of bupivacaine was 133 ml which remarkably surmounted the reference values obtained for sham perfusions. The distribution of bupivacaine into the pulmonary tissue was investigated applying the multiple indicator dilution technique to isolated lungs perfused in the single-pass mode. The mean elimination time of model compounds for distribution into the intravascular space, 14C-inulin, and the total water space, 3H-water, were 68 and 75 s at a flow rate of 6 ml/min. The volume of distribution was 5.9 ml for inulin and 6.5 ml for water. The mean transit time for concomitantly injected bupivacaine was 221 s and the volume of distribution was 14.4 ml. The respective parameters of sham perfusions performed without an isolated organ were substantially lower, i.e. mean elimination time 50, 50 and 61 s and distribution volume 4.9, 5.0 and 6.1 ml for inulin, water and bupivacaine. The volume of distribution during single-pass contact of bupivacaine to lung was not substantially influenced by an increase of the flow rate from 6 to 9 and 12 ml/min whereas the mean transit time dropped from 221 to 121 and 108 s, respectively. These results support the assumption that bupivacaine is extensively retained by the pulmonary tissue and that elimination of bupivacaine by metabolism can be neglegted for lung. The hemodynamic parameters of bronchiolar perfusion in the artificially perfused lung were determined using two fluorochrome-labeled macromolecular proteins, i.e. fluorescein-isothiocyanate (FITC)- and lissamine-rhodamine-B 200 (RB 200)-labeled globulin. After 10 min of perfusion at a flow rate of 12 ml/min in the closed system an area of 10.8% of the peribronchiolar tissue area contained the dye-label FITC. A very similar index (10.1%) of dye-coloured capillaries was obtained when the lungs of anaesthetized rats were examined 10 min after intravenous injection of the fluorochrome into the pulmonary artery in vivo. In isolated perfused rat lungs receiving both FITC and RB 200 59.5% of FITC-labeled capillaries were reached by the second fluorochrome within 2 s. This fraction accounted for 93.3% after 10 s of circulation time. This proves that isolated rat lungs were well perfused in vitro.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00169070
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Morphological instabilities in pattern formation by precipitation and crystallization processes (1996)
    Springer
    Geologische Rundschau 85 (1996), S. 19-28 
    Details
    ISSN: 0016-7835
    Schlagwort(e): Key words Anastomoses ; Crystal zoning ; Snow bands ; Liesegang rings ; Ostwald ripening ; Self organization ; Siderite ; Supersaturation theory ; Zebra rock
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract  Morphological instabilities in periodic patterns occurring both in precipitation and crystallization processes (Liesegang rings and crystal zoning) are investigated and compared with similar patterns in geological samples (zebra rocks and mud bands in snow sediments). In classical Liesegang systems, undisturbed parallel or concentric precipitation bands are emanated from even or concentric diffusion sources in homogeneous diffusion matrices of gelatine or other gels. In the case of superposing diffusion sources, sources with undulatory curvatures or local diffusion barriers there may occur several types of instabilities within the sequence of regular patterns: (a) gaps within the bands forming radial alleys free of precipitate, (b) transition from broken bands to speckled patterns and (c) apparent branching of bands linked together by so-called anastomoses. Calculations with a competitive particle growth (CPG) model show that lateral instabilities in Liesegang bands (gaps and radial alleys of gaps) are the result of Ostwald ripening effects taking place after precipitation. Apparent branching of bands or formation of anastomoses can be simulated with a prenucleation model according to Ostwald's supersaturation theory. Similar irregularities can be observed in zebra rocks (e.g. banded siderite) whose bandings are commonly explained by sequential sedimentation processes. A very different mechanism is assumed to be responsible for the origin of mud bands in snow sediments. An initially homogeneous distribution of intrinsic mud in snow sediments can be arranged into parallel bands according to a crystal zoning mechanism which is based on repeated thawing and freezing of the snow sediment due to the daily alternation of sun and darkness.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192056
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Filament formation and ethanol production by Zymomonas mobilis in adsorbed cell bioreactors (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 626-631 
    Details
    ISSN: 0006-3592
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Zymomonas mobilis immobilized on microporous ion exchange resins has previously been shown to allow the attainment of high ethanol productivities in packed-bed bioreactors. The formation of bacterial filaments after several days of continuous operation, however, had resulted in excessive pressure increases across the reactor bed. The present work examines techniques for controlling filament formation by Z. mobilis in two reactor sizes (161 mL and 7.85 L) and a feed glucose concentration of 100 g/L. By controlling the fermentation temperature at 20-25°C it has been possible to eliminate filament formation by Z. mobilis and to operate the larger bioreactor for 232 h with an ethanol productivity of 50 g/L h (based on total reactor volume). The rate of ethanol production has been shown to be very sensitive to temperature in the range 20-30°C, and it is likely that slightly higher temperatures than those used in this study will improve ethanol productivity while still permitting long-term operation.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260270512
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  • 6
    Digitale Medien
    Digitale Medien
    Synthesis and properties of the first all-aza analogue of a biologically active peptide (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 1 (1995), S. 201-206 
    Details
    ISSN: 1075-2617
    Schlagwort(e): All-aza peptide ; renin inhibitor analogue ; X-ray ; conformation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of the first all-aza-amino acid analogue (2) of a peptidic renin inhibitor is described. The X-ray structural analysis and molecular modelling investigations of this novel compound reveal interesting conformational features which have a significant impact on its biological activity. In addition, insight into conformational features of azapeptides in general in comparison with the corresponding purely peptidic compounds is given.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/psc.310010307
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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