Singlet oxygen luminescence as an in vivo photodynamic therapy dose metric: validation in normal mouse skin with topical amino-levulinic acid

Although singlet oxygen (1O2) has long been proposed as the primary reactive oxygen species in photodynamic therapy (PDT), it has only recently been possible to detect it in biological systems by its luminescence at 1270 nm. Having previously demonstrated this in vitro and in vivo, we showed that cell survival was strongly correlated to the 1O2 luminescence in cell suspensions over a wide range of treatment parameters. Here, we extend this to test the hypothesis that the photobiological response in vivo is also correlated with 1O2 generation, independent of individual treatment parameters. The normal skin of SKH1-HR hairless mice was sensitised with 20% amino-levulinic acid-induced protoporophyrin IX and exposed to 5, 11, 22 or 50 J cm−2 of pulsed 523 nm light at 50 mW cm−2, or to 50 J cm−2 at 15 or 150 mW cm−2. 1O2 luminescence was measured during treatment and the photodynamic response of the skin was scored daily for 2 weeks after treatment. As observed by other authors, a strong irradiance dependence of the PDT effect was observed. However, in all cases the responses increased with the 1O2 luminescence, independent of the irradiance, demonstrating for the first time in vivo an unequivocal mechanistic link between 1O2 generation and photobiological response

Incentive Regulation and Efficiency of Portuguese Port Authorities

In all European seaports, organisational efficiency forms a vital component of the activities to improve competitiveness in the market. As public enterprise entities, Portuguese seaports rely on government subsidies to meet their deficits. The policy of subsidisation is part of the regulatory procedures that are intended to provide incentives for increasing productive efficiency, thereby allowing seaports to share in the social gains from efficiency in the form of greater, or at least stable, employment and local development. In addition, the drive for greater efficiency is meant to assist the ports' preparation for some kind of privatisation. In this paper, we analyse the technical and allocative efficiencies of Portuguese seaport authorities in order to investigate if the state's policy is achieving its aims. We find that the results are, at best, mixed, leading us to conclude that the incentive regulation carried out by the government's regulatory body, the Maritime Port Agency, is not achieving its aims. Therefore, we propose a policy revision to enforce efficiency, based on a governance environment framework. Maritime Economics & Logistics (2003) 5, 55–69. doi:10.1057/palgrave.mel.9100060