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  • 1
    Electronic Resource
    Electronic Resource
    A quantitative assessment of protoporphyrin IX metabolism and phototoxicity in human skin following dose-controlled delivery of the prodrugs 5-aminolaevulinic acid and 5-aminolaevulinic acid-n-pentylester (2001)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 144 (2001), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Topical 5-aminolaevulinic acid (ALA) is widely used in photodynamic therapy (PDT) to generate protoporphyrin IX (PpIX) in the skin. However, other prodrugs may be more effective. Objectives The pharmacokinetics of ALA- and ALA-n-pentylester-induced PpIX, together with the phototoxicity after PDT, were compared in human skin in vivo, using iontophoresis as a quantitative drug delivery system. Methods A series of six increasing doses of equimolar prodrug solutions was iontophoresed into normal skin of the upper inner arms of 20 healthy subjects. The kinetics of PpIX metabolism in skin (n = 4) and the response to light exposure, performed at 4·5 h (n = 6) and 6 h (n = 10) after application, were assessed by skin surface PpIX fluorescence and postirradiation erythema. Results ALA and ALA-n-pentylester showed a linear correlation between logarithm of dose and PpIX fluorescence (P 〈 0·005), and logarithm of dose and skin phototoxicity with irradiation at 4·5 h (P 〈 0·001 and P 〈 0·005, respectively) and 6 h (P 〈 0·05 and P 〈 0·0001, respectively) after iontophoresis. Higher phototoxicity was observed with ALA-n-pentylester than with ALA when sites were irradiated at 6 h, as indicated by the significantly lower theoretical threshold dose for erythema (P 〈 0·05) and the shift of the PpIX fluorescence/phototoxicity curve towards greater skin erythema at equal PpIX fluorescence levels. Depth of PpIX fluorescence in skin, as determined by fluorescence microscopy, was similar for both prodrugs, but a more homogeneous distribution of PpIX was seen with the more lipophilic ALA-n-pentylester. Conclusions The observed greater phototoxicity of ALA-n-pentylester relative to ALA may be attributable to a more favourable PpIX localization in tissue and/or greater intrinsic toxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2001.04186.x
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  • 2
    Electronic Resource
    Electronic Resource
    Resonance Raman spectroscopic study of the caa3 oxidase from Thermus thermophilus (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 4 (1998), S. 365-377 
    Details
    ISSN: 1075-4261
    Keywords: resonance Raman ; Thermus thermophilus ; oxidase ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The terminal caa3 oxidase of Thermus thermophilus has been studied by resonance Raman spectroscopy. Using different excitation wavelengths in the Soret band region, it was possible to disentangle the resonance Raman spectra of the fully oxidized and fully reduced state in terms of the component spectra of the individual hemes a, a3, and c. For the heme a and a3 groups, the spectra reveal only minor differences compared to those of beef heart cytochrome c oxidase attributable to subtle modifications of the heme environment. These differences are not more pronounced than those between the oxidases from beef heart and Paracoccus denitrificans confirming the view that this oxidase of Th. thermophilus is a typical member of the aa3 oxidase superfamily. The heme c component spectra display far-reaching similarities with those of c-type cytochromes which serve as mobile electron carriers in the respiratory chain. These results imply that caa3 oxidase represents an integrated version of the noncovalent redox complex between cytochrome c and cytochrome c oxidase in higher organisms. On the other hand, the structural changes of cytochrome c in the noncovalent complex have no counterpart in the heme c component of the caa3 oxidase indicating a specific cytochrome c binding site for the mitochondrial enzyme. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: 365-377, 1998
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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