Rapid Hydrogen Shift Scrambling in Hydroperoxy-Substituted Organic Peroxy Radicals

Using quantum mechanical calculations, we have investigated hydrogen shift (H-shift) reactions in peroxy radicals derived from the atmospheric oxidation of 1-pentene (CH_2═CHCH_2CH_2CH_3) and its monosubstituted derivatives. We investigate the peroxy radicals, HOCH_2CH(OO)CR_1HCH_2CH_3, HOCH_2CH(OO)CH_2CR_1HCH_3, and HOCH_2CH(OO)CH_2CH_2CR_1H_2, where the substituent R_1 is an alcoholic (OH), a hydroperoxy (OOH), or a methoxy (OCH_3) group. For peroxy radicals with an OOH substituent, the H-shift reaction from the hydrogen atom on the OOH group to the OO group is extremely fast. We find that the rate constants of this type of H-shift reactions are greater than 10^3 s^(–1) for both the forward and the reverse reactions. It leads to the formation of two different radical isomers that react through different reaction mechanisms and yield different products. These very fast H-shift reactions are much faster than the reactions with NO and HO_2 under most atmospheric conditions and must be included in the atmospheric modeling of volatile organic compounds where hydroperoxy peroxy radicals are formed

Social Pedagogy: An Approach Without Fixed Recipes

A historical and theoretical reconstruction of the specificity and peculiarity of the discipline of social pedagogy, as it has developed in Denmark. Social pedagogy takes its departure from the idea that the individual person and the community are complementary but at the same time opposed to each other, so the task of social pedagogy is rebalancing the dynamics between the two. Social pedagogy is also characterised as a discipline with three dimensions: a practical dimension, a theoretical dimension and a professional dimension. The professional’s task is neither to apply theory in practice nor to uphold the usual practice; it is to mediate between theory and practice. The specificity of the discipline gives rise to particular challenges and dilemmas that theorists make understandable and transparent and practitioners have to deal with. A big challenge for social pedagogy is the quest for evidence-based methods that overrides the specificity of the social pedagogical approach. Balancing different forms of knowledge implies that programmes and methods are used as inspiration that can be contained in a social pedagogical approach

Programming of metabolic effects in C57BL/6JxFVB mice by in utero and lactational exposure to perfluorooctanoic acid

Perfluorooctanoic acid (PFOA) is known to cause developmental toxicity and is a suggested endocrine disrupting compound (EDC). Early life exposure to EDCs has been implicated in programming of the developing organism for chronic diseases later in life. Here we study perinatal metabolic programming by PFOA using an experimental design relevant for human exposure. C57BL/6JxFVB hybrid mice were exposed during gestation and lactation via maternal feed to seven low doses of PFOA at and below the NOAEL used for current risk assessment (3–3000 μg/kg body weight/day). After weaning, offspring were followed for 23–25 weeks without further exposure. Offspring showed a dose-dependent decrease in body weight from postnatal day 4 to adulthood. Growth under high fat diet in the last 4–6 weeks of follow-up was increased in male and decreased in female offspring. Both sexes showed increased liver weights, hepatic foci of cellular alterations and nuclear dysmorphology. In females, reductions in perigonadal and perirenal fat pad weights, serum triglycerides and cholesterol were also observed. Endocrine parameters, such as glucose tolerance, serum insulin and leptin, were not affected. In conclusion, our study with perinatal exposure to PFOA in mice produced metabolic effects in adult offspring. This is most likely due to disrupted programming of metabolic homeostasis, but the assayed endpoints did not provide a mechanistic explanation. The BMDL of the programming effects in our study is below the current point of departure used for calculation of the tolerable daily intake.The authors wish to acknowledge the support of the biotechnicians from the team of Hans Strootman at the RIVM animal facilities. Further technical support was provided by Piet Beekhof, Hennie Hodemaekers, Sandra Imholz (RIVM), Mirjam Koster (UU), Stefan van Leeuwen (RIKILT), Jacco Koekkoek and Marja Lamoree (VU). This study was funded by the European Community’s Seventh Framework Programme [FP7/2007–2013] under grant agreement OBELIX 227391

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference