Abstract. Photodynamic therapy (PDT) is now a well-established treatment modality for cutaneous carcinomas and is based on the administration of a light-activated drug followed by illumination of the pathological area. The treatment of metastatic melanoma remains a therapeutic challenge. To define the possible role of melanin in relative phototoxicity of 5-aminolevulinic acid (5-ALA), a photosensitizer used in PDT in vivo, we studied cell death in two variants (with or without melanin, B16F10 and B16G4F cells, respectively) of a melanoma cell line. Concentrations of 5-Ala up to 10 mM induced similar cytostatic effects in the B16G4F and B16F10 cells. PDT and high 5-ALA concentrations induced photocytotoxicity in both melanoma cell lines (at 10 mM for B16F10 cells and at 5 mM for B16G4F cells). Cell death corresponded to p53-dependent apoptotic signaling in pigmented B16F10 cells, whereas an autophagic response leading to a caspase-independent death was detected in nonpigmented B16G4F cells. Therefore, the PDT-induced cell death pathway appeared to correlate with melanin synthesis capacity in melanoma cells. To reduce the cytotoxicity of 5-ALA without irradiation, a low drug concentration could be used. Consequently, in combination with current therapeutics, a moderate concentration of 5-ALA and PDT may constitute a supplementary promising approach to eliminate metastatic melanoma. IntroductionPhotodynamic therapy (PDT) has been used in clinical application for many years, either systemically, or locally or topically applied to a patient bearing a lesion (cancerous or not). PDT with systemic photosensitizers has been used to treat a range of internal malignancies (lung and brain cancers) and for skin cancers (1). This cancer treatment is approved by many countries for the treatment of non-melanotic skin cancers such as basal cell carcinomas and Bowen's disease. PDT does not seem to be an appropriate treatment of melanotic melanoma in vivo, and several reasons can justify this low use. Almost all melanomas overexpress the classical ATP-binding cassette transporters (ABC protein family), leading to drug release into the extracellular medium and to the resistance by tumor cells. The antioxidant activity of melanoma is much higher than observed in other skin cancers (basal and squamous carcinomas) reducing the cytotoxic effect of ROS generated by PDT (2). Nearly all photosensitizers (PS) show a significant absorbance in ultraviolet (UV) wavelengths, while melanin absorbs a large portion of the light intended to activate PS. The light absorption by pigment strongly reduces its penetration into the tumor. Studies have been carried out with pigmented or amelanotic melanoma cells suggesting that amelanotic cells may be more susceptible to PDT (2). Among the molecules used in PDT, 5-aminolevulinic acid (5-ALA) is not itself a photosensitizer and instead it is used as a prodrug leading to the accumulation of protoporphyrin IX in the mitochondria inducing damage and subsequently cell death after light irradiation (3).It is w...

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Abstract. Knowing the quantity and biodegradability of wastewater organic matter (OM) is really essential for the optimization of modern biological treatment processes, particularly when considering the highly challenging context for sewage treatment plant operators. However, the current standard methods for wastewater characterisation, as for 5-days biochemical oxygen demand (BOD5) measurement, OM fractionation analysis and bacterial inhibitor detection, show very poor suitability for routine operational use. In this paper, the efficiency of the commercial Enverdi® method (fluorimetric respirometry) for such analytical applications is investigated, especially for the BOD5-equivalent measurement in municipal wastewater samples. The result of numerous experiments showed that the BOD5 values obtained from the alternative Enverdi® method and the main standard methods are statistically equivalent. The analytical performances of the Enverdi® method was found similar to the standard BOD5 method specifications and perfectly matched the French regulatory requirements in force. The regulatory acceptance of this method is presently under consideration. Such an outlook would be really valuable for end-users given the main advantages of this analytical solution which is time-and space-saving, user-friendly and financially competitive. In addition to BOD5 measurement, the fluorimetric respirometry displayed very promising abilities for the OM fractionation and the detection of bacterial inhibitors in wastewater.

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