Phycocyanin: laser activation, cytotoxic effects, and uptake in human XXXX .

@entity137 @entity19 @entity1110 @entity1582 @entity731 @entity3503
Phycocyanin is a phycobiliprotein with peak absorption at 620 nm. The laser activation, cytotoxic effects, and uptake into @entity731 of phycocyanin was studied. Optimal activation was produced by @entity3503 dye laser at 0.5 W and a total energy dose of 300 J/cm2 at 620 nm and 650 nm, irradiated through blood with a hematocrit of 8%. Activation was evidenced by reduction of optical density by 0.3 units at 340 nm caused by oxidation of the reduced @entity1110 ( @entity1110 ) in a buffered reaction solution containing 0.1 mg/ml of phycocyanin. @entity137 was evaluated by measuring viability of @entity19 @entity1582 cells in culture after incubation with phycocyanin (0.25 mg/ml) and irradiated by 300 J/cm2 at 514 nm. After 72 hours post-treatment the cells showed 15% viability compared to 69% and 71% for control cells exposed to laser only or phycocyanin only, respectively. Atherosclerotic artery segments obtained within 5 hours postmortem were perfused with 0.1 mg/ml phycocyanin in oxygenated Krebs Ringer solution at 30 mm Hg for 5 minutes followed by washout with phycocyanin-free Krebs for 10 minutes. Artery sections examined histologically by light and fluorescence microscopy showed specific fluorescence localization within the plaque particularly at the elastic laminae and to a larger extent at the internal elastic lamina but not in the medial muscle layer. In conclusion, phycocyanin is a cytotoxic photosensitizer that exhibits specific binding to plaque and is activated at a wavelength minimally absorbed by blood. These properties suggest potential therapeutic use for plaque localization and regression.
