Measurement of Tumor Vascular Damage in Mice with 99m Tc-MIBI Following Photodynamic Therapy

Abstract— The clinical perfusion agent ^99mTc-MIBI was used to monitor changes in tumor vascular perfusion (TVP) induced by Photofrin® (Pll)-mediated photodynamic therapy (PDT). BALB/c mice bearing an EMT-6 tumor on each hind thigh were given an intravenous injection of 1, 2 or 5 mg kg⁻¹ PII. Twenty-four hours later, one tumor was illuminated (600–650 run, 200 mW cm⁻² 400 J cm⁻²) while the other served as a control. At various time intervals after PDT (0, 2 and 24 h) mice received an intravenous injection of ^99mTc-hexakismethoxy(sobutyusonitri-le (MIBI) (0.18 MBq g⁻¹) and were sacrificed 2 min later. The light-treated and the untreated tumors were then dissected, the radioactivity was counted and the percentage of the injected dose per gram of tumor (%ID g⁻¹) was calculated as a measure of TVP. We observed that TVP is drug dose dependent, develops progressively with time post-PDT and is inversely related to PDT efficacy. Our data show that early tumor retention of ^99mMIBI is a simple method to assess TVP and vascular damage induced by PDT.     

The photo-oxidation of diethyl ether in smog chamber experiments simulating tropospheric conditions: Product studies and proposed mechanism

The products formed by the hydroxyl radical initiated photo-oxidation of diethyl ether have been investigated by irradiating synthetic air mixtures containing diethyl ether and nitrous acid in amounts approaching ppbv levels in a smog chamber. The decay of reactants and formation of products were monitored by gas chromatography, HPLC, and by chemiluminescent analysis. The major products are ethyl formate and formaldehyde, minor products include ethyl acetate, acetaldehyde, peroxyacetyl nitrate, methyl nitrate, and ethyl nitrate. The products observed arise from the decomposition reactions of the 1-ethoxyethoxy radical and its reaction with oxygen. One molecule of nitric oxide appears to be oxidized per molecule of diethyl ether reacted. This is lower than would be expected on the basis of the proposed mechanism and possible reasons for the discrepancy are discussed. © 1993 John Wiley & Sons, Inc.     

BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES—VI. PHOTOOXIDATION OF L-TRYPTOPHAN BY SELECTIVELY SULFONATED GALLIUM PHTHALOCYANINES: SINGLET OXYGEN YIELDS AND EFFECT OF AGGREGATION

Abstract— The photosensitized oxidation of L-tryptophan by gallium phthalocyanines sulfonated to different degrees is studied as a function of both substrate and sensitizer concentrations in water and 50% MeOH-H₂O solutions. The maximum quantum yield of singlet oxygen was found to be nearly 0.5 for all sulfonated gallium complexes. The effect of adding sulfonate groups in the phthalocyanine backbone is to change the tendency of dye molecules to dimerize or aggregate in a particular solvent. A shift in the chemical equilibrium away from the monomeric state, which occurs at high dye concentrations and at lower degrees of dye sulfonation, results in a reduced photochemical yield. The variation of quantum yields in different solvent systems and at several wavelengths is similarly accounted for by the fraction of light absorbed by the productive monomer state.