1,721,072 research outputs found
Efficient photoinactivation of methicillin-resistant Staphylococcus aureus by a novel porphyrin incorporated into a poly-cationic liposome
No full textAntimicrobial photodynamic therapy is emerging as a promising therapeutic modality for bacterial infections. Our studies aim at identifying strategies for optimizing the antibacterial activity of porphyrin-type photosensitisers. The photoinactivation properties of a novel, positively charged meso-substituted porphyrin, namely 5-[4-(1-dodecanoylpyridinium)]-10,15,20-triphenyl-porphyrin were tested against a typically antibiotic-resistant pathogen, such as methicillin-resistant Staphylococcus aureus. This porphyrin is characterized by an unusually large quantum yield (0.95) for the generation of the hyper-reactive oxygen species, singlet oxygen. In spite of this, it exhibits a relatively low photosensitising activity against bacteria when dissolved in a homogeneous aqueous solution or incorporated into neutral lipid vesicles. On the contrary, a dramatic potentiation of the photocydal effect takes place when polycationic agents such as liposomes of N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride are used as carriers. The cationic carrier primarily acts as a disorganizing agent for the native three-dimensional architecture of the bacterial wall, thereby enhancing its permeability to the photosensitiser. Consequently, the drug can deeply penetrate into the plasma membrane, and rapidly impair selected enzymic activities leading to cell death. Thus, the combination of positively charged drugs and cationic delivery systems appears to represent an innovative modality for achieving an efficient antimicrobial activity and opens new avenues for the development of this phototherapeutic application. (C) 2007 Elsevier Ltd. All rights reserved
Il mancato Edipo di Vittorio Alfieri
No full textIl motivo edipico nell'opera teatrale di Vittorio Alfier
Direzione e paternità spirituale negli scritti di autori gesuitici tra XVII e XVIII secolo (Rogacci, Scaramelli, Pinamonti)
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Boron neutron capture therapy and 18F-labelled borophenylalanine positron emission tomography: a critical and clinical overview of the literature
No full textHaematoporphyrin and atherosclerosis in the broad-breasted white turkey: distribution and quantitation in thoracic and abdominal aorta.
No full textSTEADY-STATE AND TIME-RESOLVED SPECTROSCOPIC STUDIES ON THE HEMATOPORPHYRIN LIPOPROTEIN COMPLEX
No full textThe interaction of hematoporphyrin (Hp) with the isolated rabbit lipoprotein fractions very low density lipoproteins, low-density lipoproteins, and high-density lipoproteins has been studied by steady-state and time-resolved spectroscopy. The porphyrin appears to be bound to both the apoprotein and the lipid phase. The two populations of lipoprotein-bound Hp molecules can be distinguished on the basis of the fluorescence excitation spectrum, decay constants of the lowest excited singlet and triplet states, and accessibility to oxygen. Upon Hp binding, the intrinsic fluorescence emission of apolipoproteins is quenched at least in part via singlet-singlet energy transfer from tryptophyl residues to the porphyrin moiety. The binding of Hp with the protein matrix can be adequately described on the basis of Scatchard analysis, whereas the interaction of Hp with the lipid core can be described as the partitioning of the dye between a hydrophobic and an aqueous phase. The Hp binding capacity of lipoproteins is maximal for very low density lipoproteins
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