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We measured the coherent backscattering of light from milk solutions and biological tissues by using a He-Ne laser (633 nm) and a CCD array as a detector. A coherent peak from the milk solutions could be measured with a single exposure. However, ensemble averaging was required for coherent peaks to be produced from solid media such as tissue samples. By fitting experimental data to an existing model numerically, effective scattering and absorption coefficients were estimated. They were compared with those computed from integrating sphere measurements. Effective scattering coefficients computed by the two different methods were in good agreement for high-scattering media. However, higher absorption was estimated by the coherent peak method.

Objective:Considering the differing mechaniisms of cytotoxicity produced by adriamycin and the photosensitizer meso-chlorin e6 monoethylene diamine (Mce6) with light, the interaction of these agants in combination on human ovarian epithelial carcinoma (OVCAR-3 in vitro) was evaluated by dose and effect addition isobole analysis.Methods:Mitochondrial respiration via the 3-(4,5-dimethyl thiazeol-2 yl)-2,5-diphenyl tetrazolium bromide cleavage assay (MTT) and reproductive capacity via the tritiated thymidine incorporation assay (TI) were assessed 72 and 144 hours after exposure to adriamycin, Mce6, and light (650 nm), and to their combinations, in OVCAR-3 cells grown in vitro (20,000 cells per well).Results:In the majority of assays, reproductive capacity was more sensitive to the drug(s) than was mitochondrial respiration (2-10X). Dose-addition isobole analysis showed synergy for the combination of 50% median effective dose (ED50) adriamycin with 50% ED50Mce6/light in all assays (all P ≤ .027). Antagonism was noted with the combination 25% ED50 adriamycin with 75% ED50 Mce6/light. Additivity and synergy were the predominant interactions for 75% ED50 adriamycin with 25% ED50 Mce6/light by dose-addition isobole analyses. Effect-addition isoboles showed a preominance of synergy, particularly for the combination 50% ED50 adriamycin with 50% ED50Mce6/light.Conclusion:Synergy and additivity are the primary in vitro interactions for the combination of adriamycin and Mce6/light in the dosage range tested. Reproductive capacity is more sensitive to the these agents than in mitochondrial respiration. [ABSTRACT FROM PUBLISHER]

Photodynamic damage to normal tissues, including skin, appears to occur by photooxidative damage to the normal microvasculature as the primary target sensitized by HPD bound to the vascular wall or endothelial cell. Initial damage to the microvasculature was measured by the increase in vascular permeability (VP) as measured by Evans Blue dye (EB) extravasation as a function of HPD and laser light (632 nm) dose. Albino, Swiss-Webster mice (♀ 122-25 g, 5 mice per group) were injected intraperitoneally (IP) with incremental doses of HPD (Photofrin II, Photofrin Medical, Inc.) (1, 10, 20, 30, 40 and 50 mg/kg). After 48 hours the left ear of each mouse was masked as a control and the right ear was irradiated at 632 nm using the Aurora-Lexel Argon-dye laser (Cooper Laser Sonics, Inc.) with an intensity of 50 mW/cm2 and light doses of 0, 25, 50, 75, and 100 J/cm2 directed to a 3-mm spot on the mouse ear. No EB leakage occurred in the absence of HPD at any light dose or in the absence of light at any HPC dose. Vascular permeability increased as a function of HPD dose up to 30 mg/kg. AT 50 mg/kg HPD, there was a decrease in VP. At each HPD dose above 10 mg/kg, the VP increased as a function of light dose up to 75 J/cm3. Further increase in light dose was without effect. The amount of HPD porphyrin recovered from irradiated ears decreased as a function of light dose. There appeared to be an irreversible photo destruction of the porphyrin exposed to light. [ABSTRACT FROM AUTHOR]