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    Discussion on Photodynamic Action of Methylene Blue (MB)
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    Abstract— The potential photodynamic therapy photosensitizers Methylene Blue, Azure C, Methylene Violet, Thionine, Methylene Green, Haematoporphyrin, Nile Blue A, chloroaluminium phthalocyanine and bis‐aluminium phthalocyanine were examined for their photoeffects and dark toxicity against a human superficial bladder carcinoma cell‐line. By examination of [ 3 H]thymidine uptake into dye‐treated cells after irradiation with a copper‐vapour pumped dye laser, it was found that Methylene Blue was the most phototoxic and dark toxic of all the dyes tested, suggesting that the dye might be of some use as a topically applied photodrug for use in photodynamic therapy of superficial or early‐recurring carcinomas.
    Among chlorophyll derivatives (CpD-A, -B, -C, and -D) extracted from silk worm (Bombyx mori) excretas, CpD-A was extensively studied to clarify its role as a "photosensitizer" for photodynamic therapy (PDT) of tumors in vitro. It was found that CpD-A was photoreactive both in itself and also in its cell bound forms. The cell bound CpD-A produced fluorescent light and singlet oxygen following the exposure to lights of varied wave length. Among them, lights of near 650 nm, which was the maximum absorbance band, efficiently activated CpD-A following the application of only 10 minutes of irradiation. CpD-A was found to have specificity for the human and mouse tumor cells regardless of their species difference. A higher intensity of fluorescence and a larger amount of CpD-A were found in the tumor cells as opposed to the intensity found in normal cells. Only 10 minutes of light irradiation of the CpD-A treated tumor cells resulted in their rapid and complete destruction within 2 hours of irradiation. Simultaneously, more than 80% of the normal human and mouse control cells remained alive after receiving treatment. These findings suggested that CpD-A produced by use of silkworm excreta could be used as a photosensitizer for PDT of tumors by the use of lights of near 650 nm.
    Absorbance
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    Background: Unwanted hair is one of the most common medical problems affecting women of reproductive age inducing a lot of psychological stress and threatening their femininity and self-esteem. Old methods of removing unwanted hair include shaving, waxing, chemical depilation, and electrolysis, all of which have temporary results. However laser-assisted hair removal is the most efficient method of long-term hair removal currently available. It is desirable to develop a reduced cost photodynamic therapy (PDT) system whose properties should include high efficiency and low side-effects. Method: Mice skin tissues were used in this study and divided into six groups such as controls, free methylene blue (MB) incubation, liposome methylene blue (MB) incubation, laser without methylene blue (MB), free methylene blue (MB) for 3 and 4 h and laser, liposome methylene blue (MB) for 3 h and laser. Methylene blue (MB) was applied to wax epilated areas. The areas were irradiated with CW He-Ne laser system that emits orange-red light with wavelength 632.8 nm and 10 mW at energy density of 5 J/cm2 for 10 min. The UV-visible absorption spectrum was collected by Cary spectrophotometer. Results: Methylene blue (MB) is selectively absorbed by actively growing hair follicles due to its cationic property. Methylene blue (MB) untreated sections showed that hair follicle and sebaceous gland are intact and there is no change due to the laser exposure. Free methylene blue (MB) sections incubated for 3 h showed that He:Ne laser induced destruction in hair follicles, leaving an intact epidermis. Treated section with free methylene blue (MB) for 4 h showed degeneration and necrosis in hair follicle, leaving an intact epidermis. Liposomal methylene blue (MB) sections incubated for 3 h showed He:Ne laser induced destruction in hair follicles with intradermal leucocytic infiltration. Conclusion: Low power CW He:Ne laser and methylene blue (MB) offered a successful PDT system in selectively damaging hair follicles, leaving an intact epidermis. The current PDT system provides better outcome than hair destruction through laser heat transfer procedures and laser-mediated hair removal, due to complete destruction of hair follicles.
    Methylene blue
    Hair removal
    Waxing
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