Paternò-Büchi reaction between aromatic carbonyl compounds and 1-(3-furyl)alkanols.

The photochemical reaction between aromatic carbonyl compounds and 3-furylmethanol derivatives occurs with high regioselectivity. In most of the experiments formation of oxetanes occurs at the hydroxyalkylated double bond. With chiral 1-(3-furyl)alkanols the reaction occurs with good-high stereoselectivity. In the case of 1-(3-furyl)-benzyl alcohol the stereoselectivity can be explained on the basis of the conformers of the reagent, assuming the formation of a complex between the carbonyl compound and the hydroxyl group.     

Characterization of the molten globule state of retinol-binding protein using a molecular dynamics simulation approach

Retinol-binding protein transports retinol, and circulates in the plasma as a macromolecular complex with the protein transthyretin. Under acidic conditions retinol-binding protein undergoes a transition to the molten globule state, and releases the bound retinol ligand. A biased molecular dynamics simulation method has been used to generate models for the ensemble of conformers populated within this molten globule state. Simulation conformers, with a radius of gyration at least 1.1 A greater than that of the native state, contain on average 37%beta-sheet secondary structure. In these conformers the central regions of the two orthogonal beta-sheets that make up the beta-barrel in the native protein are highly persistent. However, there are sizable fluctuations for residues in the outer regions of the beta-sheets, and large variations in side chain packing even in the protein core. Significant conformational changes are seen in the simulation conformers for residues 85-104 (beta-strands E and F and the E-F loop). These changes give an opening of the retinol-binding site. Comparisons with experimental data suggest that the unfolding in this region may provide a mechanism by which the complex of retinol-binding protein and transthyretin dissociates, and retinol is released at the cell surface.     

Numerical investigation on circular and elliptical bulge tests for inverse soft tissue characterization

Biomechanics and Modeling in Mechanobiology - The acquisition of insights concerning the mechanobiology of aneurysmatic aortic tissues is an important field of investigation. The complete...     

Overexpression of ornithine decarboxylase increases myogenic potential of H9c2 rat myoblasts

Myoblast differentiation into multinuclear myotubes implies the slow-down of their proliferative drive and the expression of myogenin, an early marker of myogenic differentiation. Natural polyamines—such as putrescine, spermidine and spermine—are low molecular weight organic polycations, well known as mediators involved in cell homeostasis. Many evidences in the literature point to their role in driving cellular differentiation processes. Here, we studied how polyamines may affect the differentiation of the myogenic cell line H9c2 into the muscle phenotype. Cell cultures were committed via a 7-day treatment with insulin which induced increase in the activity of ornithine decarboxylase, the first enzyme in the polyamine biosynthetic pathway, consistent with myogenic differentiation. To evaluate the role of polyamines in the differentiation process, cells were transfected with a plasmid overexpressing a stable ornithine decarboxylase, under control of a constitutive promoter. Overexpressing cells spontaneously differentiate into myotubes, without the need for induction with insulin; multinuclear myotubes and myogenin expression were apparent within 2 days of confluency of cultures. Polyamine depletion—by means of α-difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase—abolished the differentiation process. These observations support the evidence that polyamines are a key step involved in differentiation of muscle cells.