1,721,395 research outputs found
3° Motivation et attitudes, par F. Orsini
No full textOrsini F. 3° Motivation et attitudes, par F. Orsini. In: L'année psychologique. 1959 vol. 59, n°1. pp. 247-251
SmI2-mediated reactions of diethyl iodomethylphosphonate with esters and lactones: a highly stereoselective synthesis of a precursor of the C-glycosyl analogue of thymidine 5′-(β-l-rhamnosyl)diphosphate
No full textIn the presence of samarium iodide diethyl iodomethylphosphonate reacts with esters to afford beta-ketophosphonates. The protocol has been applied to sugar lactones to afford in fairly good yields intermediates that are useful precursors for a variety of potentially bioactive compounds, such as the C-glycosyl analogue of thymidine 5'-(beta-L-rhamnosyl)diphosphate
Transition metals-mediated reformatsky reactions
No full textThe reaction of alpha-haloesters and carhonyl compounds in the presence of metallic zinc to give beta-hydroxy esters represents a powerful synthetic tool for carbon-carbon bond formation. Since its discovery by Reformatsky, this reaction has been undergoing several improvements and its scope and selectivity have been considerably extended. To this purpose many parameters, such as metal activation. reaction temperature, solvent, properly designed reactants and substrates have been investigated. Furthermore, reactions are not restricted to the use of Zinc, but include a variety, of other metals or metal derivatives. Among them, transition metals may offer important advantages in terms of milder conditions, higher reproducibility and stereosclectivity
Alcohol and 1,2-diol dehydrogenases : synthetic use as oxidants
No full textThe redox equilibrium between alcohol - carbonyl groups is greatly used by enzymes and chemists to prepare useful compounds. Carbonyls are often intermediate groups whose reactivity can be used to synthesize complex Structures: in contrast, alcohols are more easily found in the products of interest because their coordinative ability is used both in biology and in chemistry. Dehydrogenase activities are an interesting alternative to chemical redox reactants because they are often chemo-. regio-. and stereo-selective. These enzymes allow for two different uses: direct, as racemates resolving agents-, inverse. as enantioselective reducing agents. We will focus on their use as oxidative agents. considering both the well-known alcohol dehydrogenases and the less known and less used 1,2-diol dehydrogenases. An account of both classes will be presented
Recent Developments in the Use of Magnetic Fluid Hyperthermia on Glioblastoma Multiforme Disease
Full text linkThe first evidence of the efficacy in the cancer treatment of hyperthermia, therapy focused on the heating of tumor masses to kill cells and tissues, went back almost a century and a half. One of the most promising techniques for increasing the cells and tissues temperature is based on the use of magnetic nanoparticles dispersed in concentrated colloidal suspensions and stimulated by an external alternating electromagnetic field, known as Magnetic Fluid Hyperthermia. Recently this technique has been used as coadjutant treatment of the most applied chemo and radio therapies in a series of different tumors, but in particular for Glioblastoma Multiforme till to clinical trials level. In this work, we report some of most significant progresses regarding the use of Magnetic Fluid Hyperthermia on Glioblastoma Multiforme disease published in literature during the last year, describing the more interesting outcomes for potential future clinical applications
A new entry to β-hydroxyphosphonates: the SmI2-mediated reaction of diethyl iodomethylphosphonate with carbonyl compounds
No full textIn the presence of samarium iodide alpha-halophosphonates react with aliphatic carbonyl compounds (aldehydes and ketones) to afford beta-hydroxyphosphonates in fairly good yields under neutral and mild conditions. Lower yields are obtained with aromatic carbonyl compounds
Alcohol and 1,2-diol dehydrogenases: synthetic use in the preparation of chiral alcohols by carbonyl reduction
No full textChiral alcohols are useful intermediates and auxiliaries in organic synthesis. Their preparation in enantiopure form is consequently of very high interest. Among the different enzymatic procedures, the use of dehydrogenase activities can be considered as the most attractive alternative. These enzymes can fruitfully work in inverse direction as enantioselective reducing agents. We will focus on the use of well-known alcohol dehydrogenases, describing their application in chiral alcohol preparation. A final discussion on the possibility of using these enzymes in either oxidative or reductive direction will be presented
Atomic Force Microscopy Imaging of Xenopus laevis Oocyte Plasma Membrane
No full textThis chapter describes the application of atomic force microscopy (AFM) to the study of the Xenopus laevis oocyte plasma membrane. Different sample preparation protocols developed and optimized to perform AFM investigation of both external and intracellular sides of the oocyte native plasma membrane are presented and discussed. AFM imaging allowed visualization and dimensional characterization of protein complexes observed on both sides of the oocyte plasma membrane. In addition, a methodological approach based on the purification of oocyte plasma membrane by ultracentrifugation on a discontinuous sucrose gradient allowed to image oocyte membrane in a physiological-like environment as well as to identify a membrane protein, the human aquaporin 4, expressed in the oocytes. Taken together, these results confirm the potential of AFM as an useful tool for the structural characterization of proteins in native eukaryotic membranes as well as its relevance for describing the organization of protein complexes in native biological membranes
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