11,261 research outputs found
Il Sole in testa
No full textTraduzione dei racconti di esordio dello scrittore brasiliano G. Martins
Naked genes : reinventing the human in the molecular age
No full textThe molecular life sciences are making visible what was once invisible. Yet the more we learn about our own biology, the less we are able to fit this knowledge into an integrated whole. Life is divided into new sub-units and reassembled into new forms: from genes to clones, from embryonic stages to the building-blocks of synthetic biology. Extracted from their scientific and social contexts, these new entities become not only visible but indeed “naked”: ready to assume an essential status of their own and take on multiple values and meanings as they pass from labs to courts, from patent offices to parliaments and back.
In Naked Genes, leading science scholar Helga Nowotny and molecular biologist Giuseppe Testa examine the interaction between these dramatic advances in the life sciences and equally dramatic political reconfigurations of our societies. Considering topics ranging from assisted reproduction and personalized medicine to genetic sports doping, they reveal both surprising continuities and radical discontinuities between the latest advances in the life sciences and long-standing human traditions
Molecular fields to assess recognition forces and property spaces
No full textSince the emergence of combinatorial chemistry and chemical libraries, great attention is being paid to the concepts of chemical diversity and chemical space. This approach is based on the assumption that molecular properties are invariant ones. But a growing computational power shows that a molecule cannot be considered as a static object but as an animated subject whose conformational changes may significantly affect the profile of any of its computable property. The ensemble of all conformers of a given compound is often taken as defining a conformational space. In a similar manner, many molecular properties can be shown to vary with the 3D-geometry of the molecule.
In particular, powerful computational methods based on molecular fields now allow some physicochemical properties to be computed for each conformer, as discussed in the first part of the chapter. Such methods include MEPs (Molecular Electrostatic Potentials), MLPs (Molecular Lipophilicity Potentials), which allows to back-calculate a partition coefficient of a given conformer, and the recent MHBPs (Molecular Hydrogen-Bonding Potentials). A range of property values corresponding to all realistic conformations must be examined and taken into account. The range of these values defines a property space whose form and extent will depend on both the solute and the relevant environment.
In a second part, the chapter focuses on the property spaces of the acetylcholine in a variety of polar and hydrophobic solvents. The effect of the solvent on the conformational behaviour of acetylcholine is analyzed together with the corresponding effects on the property spaces. Moreover, attention is being paid to the cross-correlation among the profiles of these spaces (both physicochemical and structural). These interrelations lead to a definition of the concept of molecular sensitivity which describes the ability of a molecule to modify its physicochemical properties as its geometry changes, as presented in the third part of the chapter. The receptor selectivity of alpha-adrenergic ligands offers an illustration of the interest and limits of molecular sensitivity and property space range in dynamic QSAR analyse
Musings on ADME predictions and molecular structure
No full textIn this overview, we first examine Structure-Activity Relations (SARs) and their components from a general point of view. Four types of interpretation emerging from statistically valid relations are considered, namely causal (mechanistic), contextual (empirical), fortuitous and tautological correlations. Implications for ADME predictions arise when discussing the diversity of interactions between active compounds (e.g. drugs) and biological systems.
In a second part, we share our views on the differences between pharmacodynamic targets (namely the sites of action of bioactive compounds, e.g. receptors and ion channels) and pharmacokinetic agents (namely the biological components that act on drugs to transport, metabolize, retain and excrete xenobiotics). While the former are usually characterized by a high (i.e., narrow) specificity towards their ligands, the latter have evolved to recognize chemically diverse compounds and thus to display a low (i.e., broad) specificity.
In a last part, we discuss the concept of molecular structure and focus on the fluctuations undergone by molecular form and functions. As a result, a molecule can exist in a large number of distinct microstates, the ensemble of which constitutes the property space of the molecul
Dalla cultura nel distretto alla cultura del distretto: una esperienza universitaria in atto
No full textI grandi acquafortisti italiani del Seicento: Testa, Castiglione e Rosa
No full textPanoramica dei grandi protagonisti dell'acquaforte in Italia nel 600: Salvator Rosa, Pietro Testa, G. B. Castiglion
The Italian Pathways of Stem Cells
No full textIn this contribution, we take a look at the future of stem cell research, with particular emphasis on human embryonic stem cells and induced Pluripotent Stem Cells (iPS). Their implications in terms of ethical and social issues are discussed through interviews with two top Italian scientists, Elena Cattaneo and Giuseppe Testa. In light of their answers, the introduction reflects on how stem cells research, interpreted from an STS perspective, allows us to observe the mutual adaptation between scientific practices which generate multiple biological artifacts, and the many ethical implications which characterize our biotechnological societies
The time of timing: how Polycomb proteins regulate neurogenesis
No full textThe study of mammalian corticogenesis has revealed a critical role for Polycomb group (PcG) factors in timing the execution of developmental choices. Meanwhile, the study of post-translational modifications of PcG factors marks a symmetrical point, namely that the activity of PcG proteins is itself timed in a manner that links progression through the cell cycle to targeting of downstream genes. Finally, in a third symmetrical twist, the studies that dissect the timing of neural fate by Polycomb are also uncovering the importance of timing in the experimental mutation, since ablation of the same PcG member at different developmental stages yields dramatically different results. Here, I weave together these three lines of evidence and develop a unifying model that clarifies the dynamics of Polycomb function in neural development and defines the salient challenges ahead
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