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Mitochondrial cytochrome c oxidase activity was inhibited by exposure to hematoporphyrin derivative followed by photoirradiation. Inhibition of enzyme activity in vitro was a dose- and time-related event, the log of percentage inhibition being linear with time. Exposure of mitochondria to hematoporphyrin or hydroxyethylvinyldeuteroporphyrin sensitized(More)
Effects of oxygen consumption in photodynamic therapy (PDT) are considered theoretically and experimentally. A mathematical model of the Type II mechanism of photooxidation is used to compute estimates of the rate of therapy-dependent in vivo oxygen depletion resulting from reactions of singlet oxygen (1O2) with intracellular substrate. Calculations(More)
We examined the effectiveness of systemic administration of delta-aminolevulinic acid (delta-ALA) to induce endogenous protoporphyrin as a regimen for use in photodynamic therapy (PDT) of transplanted R3230AC rat mammary adenocarcinomas in vivo. Levels of porphyrins synthesized in various tissues after systemic administration of delta-ALA differed, with(More)
A partial saturation method is described for obtaining rapid images of tissue 1H spin-lattice relaxation rates following administration of the paramagnetic contrast agent gadolinium-diethylenetriaminepentaacetate. The paramagnetic contribution to the relaxation rates is proportional to the concentration of contrast agent, making possible quantitative(More)
Recently, we reported that the delta-aminolevulinic acid (delta-ALA)-induced increase in porphobilinogen deaminase (PBGD) activity was closely correlated with an increase in the accumulation of protoporphyrin IX (PPIX), resulting in augmented phototoxicity. In this report, we asked whether increasing the cellular expression of PBGD by use of gene(More)
A series of thiopyrylium (2), selenopyrylium (3), and telluropyrylium dyes (4) was prepared via the addition of Grignard reagents to either 2, 6-di(4-dimethylamino)phenylchalcogenopyran-4-ones (5a) or 2-[4-(dimethylamino)phenyl]-6-phenylchalcogenopyran-4-ones (5b) followed by elimination and ion exchange to give the chloride salts. The absorption spectra(More)
Photodynamic therapy (PDT), a novel treatment for a variety of human malignancies, usually consists of visible light irradiation of lesions following the systemic administration of a photosensitizer. Induction of the endogenous photosensitizer protoporphyrin IX by the systemic or topical administration of delta-aminolevulinic acid (delta-ALA) is being(More)
Photodynamic therapy (PDT) is efficacious in the treatment of small malignant lesions when all cells in the tumour receive sufficient drug, oxygen and light to induce a photodynamic effect capable of complete cytotoxicity. In large tumours, only partial effectiveness is observed presumably because of insufficient light penetration into the tissue. The(More)
The response to Photofrin II-induced photosensitization on the activities of mitochondrial monoamine oxidase (MAO) and adenylate kinase (AK) were studied in order to gain further insight into site specific effects. Utilizing intact mitochondria in vitro, both MAO, located on the cytoplasmic side of the outer mitochondrial membrane, and AK, located in the(More)
Clinical photodynamic therapy consists of the systemic administration of a derivative of hematoporphyrin (Photofrin II) followed by exposure of malignant lesions to continuous visible laser irradiation. We investigated the effects of various modifications of laser light delivery on the efficacy of photodynamic therapy in controlling R3230AC mammary tumor(More)