77 research outputs found

    The Discovery and Future Prospects of Artificial Porphyrins: Molecular Batteries Functioning with the Reversible Formation and Cleavage of Cyclopropane Units

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    The absence of the meso-hydrogen atoms in meso-octaalkylporphyrinogens enable the generation of novel forms of the oxidized porphyrinogen, 'artificial porphyrins'. A stepwise four-electron oxidation of meso-octaalkylporphyrinogen transitionmetal complexes led to an unusual aromatization of the porphyrinogen with the loss of four hydrogen atoms and the introduction of one, followed by two cyclopropane units into the porphyrinogen frame. Such oxidized forms of porphyrinogen function as two-electron shuttles via the formation and cleavage of the cyclopropane unit. Furthermore, the appropriate site opening of the cyclopropane may lead to important modifications of the porphyrinogen frame

    Chemical composition and biological activities of the leaves of Cynara scolymus L. (artichoke) cultivated in Brazil

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    The present paper describes the chemical composition and biological activities of artichoke cultivated in Brazil. Our studies demonstrated that glycosyl flavonoids (cynaroside and scolymoside), are the major constituents, along with cynaropicrin, a sesquiterpene lactone, and the triterpene lupeol. Cynarin, which is the main compound described for artichoke, was detected in very low concentration. Hexanic fraction exhibited considerable cytotoxicity and diuretic activities

    Approaches to interim analysis of cancer randomised clinical trials with time to event endpoints: A survey from the Italian National Monitoring Centre for Clinical Trials

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    <p>Abstract</p> <p>Background</p> <p>Although interim analysis approaches in clinical trials are widely known, information on current practice of planned monitoring is still scarce. Reports of studies rarely include details on the strategies for both data monitoring and interim analysis. The aim of this project is to investigate the forms of monitoring used in cancer clinical trials and in particular to gather information on the role of interim analyses in the data monitoring process of a clinical trial. This study focused on the prevalence of different types of interim analyses and data monitoring in cancer clinical trials.</p> <p>Methods</p> <p>Source of investigation were the protocols of cancer clinical trials included in the Italian registry of clinical trials from 2000 to 2005. Evaluation was restricted to protocols of randomised studies with a time to event endpoint, such as overall survival (OS) or progression free survival (PFS). A template data extraction form was developed and tested in a pilot phase. Selection of relevant protocols and data extraction were performed independently by two evaluators, with differences in the data assessment resolved by consensus with a third reviewer, referring back to the original protocol. Information was obtained on a) general characteristics of the protocol b) disease localization and patient setting; c) study design d) interim analyses; e) DSMC.</p> <p>Results</p> <p>The analysis of the collected protocols reveals that 70.7% of the protocols incorporate statistical interim analysis plans, but only 56% have also a DSMC and be considered adequately planned. The most concerning cases are related to lack of any form of monitoring (20.0% of the protocols), and the planning of interim analysis, without DSMC (14.7%).</p> <p>Conclusion</p> <p>The results indicate that there is still insufficient attention paid to the implementation of interim analysis.</p

    Density Functional Study of Metallacumulene Complexes

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