Visualization of bronchoalveolar fistula as the presenting sign of lung cancer

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Partial least squares path modelling for the evaluation of patients' satisfaction after thoracic surgical procedures☆

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Antioxidant effects of resveratrol in cardiovascular, cerebral and metabolic diseases.

Resveratrol-a natural polyphenolic compound-was first discovered in the 1940s. Although initially used for cancer therapy, it has shown beneficial effects against most cardiovascular and cerebrovascular diseases. A large part of these effects are related to its antioxidant properties. Here we review: a) the sources, the metabolism, and the bioavailability of resveratrol; b) the ability of resveratrol to modulate redox signalling and to interact with multiple molecular targets of diverse intracellular pathways; c) its protective effects against oxidative damage in cardio-cerebro-vascular districts and metabolic disorders such as diabetes; and d) the evidence for its efficacy and toxicity in humans. The overall aim of this review is to discuss the frontiers in the field of resveratrol's mechanisms, bioactivity, biology, and health-related use

The Hexameric Resorcinarene Capsule at Work: Supramolecular Catalysis in Confined Spaces

The hexameric resorcinarene capsule reported by Atwood in 1997 is able to act as a supramolecular catalyst. Its inner cavity provides a unique environment, in which organic reactions can be efficiently catalyzed, thanks to the confinement effect of the substrates. In addition, different stereo- and regiochemical outcomes can be observed with respect to reactions in the bulk solvent. The hexameric capsule shows some catalytic features reminiscent of natural enzymes. In particular, highlights of the capsule discussed herein include 1) its ability to recognize the substrates (substrate selectivity), 2) the possibility of stabilizing the transition states and intermediates through secondary interactions, 3) an inherent Brønsted acidity, and 4) its ability to act as a hydrogen-bond catalyst. In addition, it is also shown how the catalytic activity of the hexameric capsule can be modulated in the presence of competitive alkylammonium guests, which show high affinities for its internal cavity. These aspects are discussed through a critical examination of data reported in the literature in recent years

Exploiting the hydrophobicity of calixarene macrocycles for catalysis under “on-water” conditions

An example of calixarene-mediated catalysis under “on-water” conditions is here reported. In the presence of thioureido-calixarenes a rate acceleration for the Vinylogous Mukaiyama Aldol Reaction (VMAR) was observed, under on-water conditions. The ability of the calixarene catalyst to accelerate the VMAR under on-water conditions is closely related to its hydrophobicity and to its recognition abilities toward the substrat

Michael addition reactions inside a self-assembled resorcin[4]arene hexameric capsule

In the last few years there has been a significant growth of interest in performing different types of reactions in confined nanometer-scale spaces taking inspiration from the biological reactions catalysed by natural enzyme in their hydrophobic pocket.[1] In fact, the confinement of the substrates within a molecular container can lead to new reactivities and selectivities different from those normally observed in the bulk medium. Resorcin[4]arene hexameric capsules [2],[3] have been already exploited as nanoreactors thanks to their ease of preparation, their large cavity, and their ability to encapsulate different substrates and stabilize cationic intermediate.[4] Our group recently highlighted that the hydrogen-bond-donor capabilities of the bridging water molecules of the capsule are able to promote the Friedel-Crafts benzylation reaction with high efficiency and regioselectivity.[5] On this basis, we envisioned that this capability of the hexameric resorcinarene capsule could play a role in the catalysis of Michael addition of pyrrole to electron-deficient nitroolefins through the hydrogen-bonding activation of the nitroolefin and we herein report our recent results

Threading of an Inherently Directional Calixarene Wheel with Oriented Ammonium Axles

The threading of monostoppered alkylbenzylammonium axles 7+ and 8+ with the calix[6]-wheel 3 can occur by both routes of entering the macrocycle 3 in the cone conformation: passage through the upper rim and the through the lower rim. Thus, under thermodynamic conditions, with both the axles 7+ and 8+, the two possible orientations of calix[2]pseudorotaxane, namely, endo-benzyl and endo-alkyl, are formed by a stereoselectivity controlled by the endo-alkyl rule. Interestingly, by 1H NMR monitoring of the threading process between 8+ and 3, we revealed two calix[2]pseudorotaxane isomers in which the calix-wheel adopts 1,2,3-alternate and cone conformations, which represent the kinetic and thermodynamic species, respectively. Finally, the synthesis of ammonium-based oriented calix[2]rotaxane is here described

The Hexameric Resorcinarene Capsule as a Brønsted Acid Catalyst for the Synthesis of Bis(heteroaryl)methanes in a Nanoconfined Space

Herein, we show that the hexameric resorcinarene capsule C is able to catalyze the formation of bis(heteroaryl)methanes by reaction between pyrroles or indoles and carbonyl compounds (a-ketoesters or aldehydes) in excellent yields and selectivity. Our results suggest that the capsule can play a double catalytic role as a H-bond catalyst, for the initial activation of the carbonyl substrate, and as a Brønsted acid catalyst, for the dehydration of the intermediate alcohol

Bioinspired supramolecular organocatalysis mediated by macrocyclic scaffolds

Enzymes are the fascinating promoters of biosynthetic processes and are responsible for their high efficiency and selectivity. During the last years, the development of new bioinspired artificial catalytic systems taking natural enzymes as a blueprint has become an exciting area of research. Many kinds of artificial enzymes have been prepared based on different supramolecular scaffolds ranging from macrocycles to molecular containers trying to mimic the confined environment and the molecular recognition abilities of the enzyme pocket. As a part of our ongoing investigations on the design and use supramolecular enzyme mimics,we report here our recent results based on the use of calixarene derivatives as supramolecular organocatalysts in the synthesis of heterocyclic rings, building blocks in various biologically and pharmacologically active compounds. These macrocycles, thanks to their hydrophobic cavities, are able to recognize and to host selectively the substrates isolating them from the reaction environment. Their ease of functionalization permits to introduce useful functional groups in close proximity of the hydrophobic binding sites

Exploiting the p-Bromodienone Route for the Formation and Trapping of Calixarene Oxenium Cations with Enamine Nucleophiles

This study shows that calixarene p-bromodienone derivatives can act as precursors for the formation of oxenium cations, which can be trapped with enamine C-nucleophiles. When calixarene p-bromodienones were treated with enamines, in the presence of AgClO4, the lower rim-substituted C-O-C products were obtained by an electrophilic attack of the intermediate calixarene-oxenium cation with a contemporary cone-to-partial-cone inversion of the involved aromatic ring