Desarrollo sustentable en América Latina : oportunidades para la próxima década

Amyloid fibrils formed by the 29-residue peptide hormone glucagon at different concentrations have strikingly different morphologies when observed by transmission electron microscopy. Fibrils formed at low concentration (0.25 mg/mL) consist of two or more protofilaments with a regular twist, while fibrils at high concentration (8 mg/mL) consist of two straight protofilaments. Here, we explore the structural differences underlying glucagon polymorphism using proteolytic degradation, linear and circular dichroism, Fourier transform infrared spectroscopy (FTIR), and X-ray fiber diffraction. Morphological differences are perpetuated at all structural levels, indicating that the two fibril classes differ in terms of protofilament backbone regions, secondary structure, chromophore alignment along the fibril axis, and fibril superstructure. Straight fibrils show a conventional beta-sheet-rich far-UV circular dichroism spectrum whereas that of twisted fibrils is dominated by contributions from beta-turns. Fourier transform infrared spectroscopy confirms this and also indicates a more dense backbone with weaker hydrogen bonding for the twisted morphology. According to linear dichroism, the secondary structural elements and the aromatic side chains in the straight fibrils are more highly ordered with respect to the alignment axis than the twisted fibrils. A series of highly periodical reflections in the diffractogram of the straight fibrils can be fitted to the diffraction pattern expected from a cylinder. Thus, the highly integrated structural organization in the straight fibril leads to a compact and highly uniform fibril with a well-defined edge. Prolonged proteolytic digestion confirmed that the straight fibrils are very compact and stable, while parts of the twisted fibril backbone are much more readily degraded. Differences in the digest patterns of the two morphologies correlate with predictions from two algorithms, suggesting that the polymorphism is inherent in the glucagon sequence. Glucagon provides a striking illustration of how the same short sequence can be folded into two remarkably different fibrillar structures. (C) 2010 Elsevier Ltd. All rights reserved

Solid phase synthesis of Ψ[CH(CN)NH] pseudopeptides. Application to the synthesis of analogues of neurotensin [NT(8-13)]

The introduction of the cyanomethyleneamino [CH(CN)NH] group, a new type of peptide bond surrogate, under solid phase peptide synthesis conditions has been studied using both Boc and Fmoc strategies. The pseudohexapeptides H-Arg-Pro-Tyrψ[CH(CN)NH]Ile-Leu-OH (1) and H-Arg-Arg-Pro-Tyr-Ileψ[CH(CN)NH]Leu-OH (2), analogues of the C-terminal hexapeptide of neurotensin [NT(8–13)], were successfully obtained via Fmoc synthesis. The solid phase synthesis of the ψ[CH(CN)NH] pseudopeptides 1 and 2, NT(8–13) analogues, is described.We thank Novo Nordisk A/S, Comisión Interministerial de Ciencia y Tecnología and Cornunidad Autónoma de Madrid for financial support

Method Development for Reversed-Phase Separations of Peptides: A Rational Screening Strategy for Column and Mobile Phase Combinations with Complementary Selectivity

This review article summarizes the results obtained from the combined efforts of a joint academic and industrial initiative to solve the real-life challenge of determining low levels of peptide-related impurities (typically 0.05–1% of the drug substance) in the presence of the related biologically active peptide at a high concentration. A rational screening strategy for pharmaceutically important peptides has been developed that uses combinations of reversed‑phase ultrahigh-pressure liquid chromatography (UHPLC) columns and mobile phases that exhibit complementary reversed-phase chromatographic selectivity using either UV- or mass spectrometry (MS)-compatible conditions. Numerous stationary and mobile phases were categorized using the chemometric tool of principal component analysis (PCA), employing a novel characterization protocol utilizing specifically designed peptide probes. This was successfully applied to the development of a strategy for the detection of impurities (especially isomers) in peptide drug substances using two-dimensional liquid chromatography coupled with MS detection (2D-LC–MS)

Redox-dependent regulation of the Na+-K+ pump: new twists to an old target for treatment of heart failure

By the time it was appreciated that the positive inotropic effect of cardiac glycosides is due to inhibition of the membrane Na-K pump, glycosides had been used for treatment of heart failure on an empiric basis for ~200years. The subsequent documentation of their lack of clinical efficacy and possible harmful effect largely coincided with the discovery that a raised Na concentration in cardiac myocytes plays an important role in the electromechanical phenotype of heart failure syndromes. Consistent with this, efficacious pharmacological treatments for heart failure have been found to stimulate the Na-K pump, effectively the only export route for intracellular Na in the heart failure. A paradigm has emerged that implicates pump inhibition in the raised Na levels in heart failure. It invokes protein kinase-dependent activation of nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) and glutathionylation, a reversible oxidative modification, of the Na-K pump molecular complex that inhibits its activity. Since treatments of proven efficacy reverse the oxidative Na-K pump inhibition, the pump retains its status as a key pharmacological target in heart failure. Its role as a target is well integrated with the paradigms of neurohormonal abnormalities, raised myocardial oxidative stress and energy deficiency implicated in the pathophysiology of the failing heart. We propose that targeting oxidative inhibition of the pump is useful for the exploration of future treatment strategies. This article is part of a Special Issue entitled "NaRegulation in Cardiac Myocytes"

Presenteeism, stress resilience, and physical activity in older manual workers: a person-centred analysis

© 2017 Springer-Verlag Berlin HeidelbergThis study used a person-centred approach to explore typologies of older manual workers based on presenteeism, stress resilience, and physical activity. Older manual workers (n = 217; 69.1% male; age range 50–77; M age = 57.11 years; SD = 5.62) from a range of UK-based organisations, representing different manual job roles, took part in the study. A cross-sectional survey design was used. Based on the three input variables: presenteeism, stress resilience and physical activity, four distinct profiles were identified on using Latent Profile Analysis. One group (‘High sport/exercise and well-functioning’; 5.50%) engaged in high levels of sport/exercise and exhibited low levels of stress resilience and all types of presenteeism. Another profile (‘Physically burdened’; 9.70%) reported high levels of work and leisure-time physical activity, low stress resilience, as well as high levels of presenteeism due to physical and time demands. A ‘Moderately active and functioning’ group (46.50%) exhibited moderate levels on all variables. Finally, the fourth profile (‘Moderately active with high presenteeism’; 38.20%) reported engaging in moderate levels of physical activity and had relatively high levels of stress resilience, yet also high levels of presenteeism. The profiles differed on work affect and health perceptions largely in the expected directions. There were no differences between the profiles in socio-demographics. These results highlight complex within-person interactions between presenteeism, stress resilience, and physical activity in older manual workers. The identification of profiles of older manual workers who are at risk of poor health and functioning may inform targeted interventions to help retain them in the workforce for longer