1,721,017 research outputs found
The production of singlet molecular oxygen by zinc(II) phthalocyanine in ethanol and in unilamellar vesicles. Chemical quenching and phosphorescence studies.
No full textAntimicrobial photodynamic therapy: photophysical and phototoxic activities of conjugates of apidaecin with different photosensitizers
No full textAntimicrobial PhotoDynamic Therapy (APDT) represents a very promising strategy, particularly for the treatment of localized infectious diseases.[1] PDT involves the use of a non-toxic photosensitizer (PS) that forms reactive oxygen species (ROS) when irradiated with visible light of appropriate wavelength. ROS (e. g. 1O2) can cause irreversible damages to a variety of cellular components, resulting in cytotoxicity. Advantages of APDT over traditional antibiotics include a broad spectrum activity, also against antibiotic-resistant species and the lack of development of resistance mechanisms due to the multi-target process. Whereas Gram-positive bacteria can be efficiently killed by light after incubation with a number of PS, Gram-negative bacteria are less susceptible to photodynamic killing. Only cationic PS can bind efficiently to Gram-negative bacteria and induce their photoinactivation. Recently we have shown that the conjugation of a cationic antimicrobial peptide (apidaecin 1b ) to a neutral porphyrin afforded a new antibacterial agent with a broader spectrum activity than two individual components or a mixture of them.[2] Here we present the results obtained with two new PS-apidaecin conjugates in which either a porphycene (G), a structural porphyrin isomer, or a cationic porphyrin (Y) are covalently linked to the peptide N-terminal end. By a combination of spectroscopic and time resolved photophysical techniques, we have monitored the ability of conjugates to produce the main cytotoxic species (1O2) in different solvents and in E. coli (the prototypical Gram-negative bacterium), obtaining information on the possible localization of the PS in the cell. The photokilling activity of the conjugates was markedly concentration-dependent, and the most potent one, Y-apidaecin, caused complete killing of bacteria at 10 μM (E. coli) and 1.5 μM (S. aureus) concentrations.
References
1. Hamblin, M. R.; Hasan, T. Photochem. Photobiol. Sci. 2004, 3, 436-450
2. Dosselli, R.; Gobbo, M.; Bolognini, E.; Campestrini, S.; Reddi E. ACS Med. Chem. Lett. 2010, 35-38
Going 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Photosensitizing proteins for a targeted antibacterial photodynamic inactivation
No full textOne of the emerging global health threats is the drug-resistant microbial diseases that could cause millions of deaths each year by 2050. A very promising tool to tackle antimicrobial resistance is photodynamic therapy that exploits the ability of a photosensitizer to generate oxidizing species upon illumination to kill bacteria. The research activity in this field is very active and, following this approach, we aim to develop a targeted theranostic agent where a protein is used as a “modular” carrier, transporting a fluorescent photosensitizer, and an antibody to confer selectivity to the photodynamic effect
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