Implication of two new paradigms for futures studies

The paper considers the emergence of two recent perspectives in futures work. One is evolutionary futures studies. The other is critical futures studies. After describing aspects of each, the paper considers them as alternative rival paradigms in relation to criteria that include: the role of the human being as a subject, the role of interpretation and differences in methodological premises. It concludes that both have contributed to the development of futures methods but that a number of theoretical and methodological problems still remain unsolved

The food additives inulin and stevioside counteract oxidative stress

Prebiotics such as inulin (Inu)-type fructans and alternative natural sweeteners such as stevioside (Ste) become more popular as food ingredients. Evidence is accumulating that carbohydrates and carbohydrate-containing biomolecules can be considered true antioxidants, capable of scavenging reactive oxygen species (ROS). Here, we report on the ROS scavenging abilities of Inu and Ste in comparison with other sugars, sugar derivatives and arbutin. It is found that Inu and Ste are superior scavengers of both hydroxyl and superoxide radicals, more effective than mannitol and sucrose. Other compounds, such as 1-kestotriose, trehalose, raffinose and L-malic acid, also showed good reactivity to at least one of the two oxygen free radicals. The strong antioxidant properties of Inu and Ste are discussed. Within the plant vacuole, these compounds could play a crucial role in antioxidant defense mechanisms to help survive stresses. Addition to food assists in natural sweetening, food stabilization and maximizes health impact.status: publishe

Antioxidant defence in UV-irradiated tobacco leaves is centred on hydrogen-peroxide neutralization

Greenhouse grown tobacco (Nicotiana tabacum L. cv. Petit Havana) plants were exposed to supplemental UV centred at 318 nm and corresponding to 13.6 kJ m-2 d-1 biologically effective UV-B (280e315 nm) radiation. After 6 days this treatment decreased photosynthesis by 30%. Leaves responded by a large increase in UV-absorbing pigment content and antioxidant capacities. UV-stimulated defence against ROS was strongest in chloroplasts, since activities of plastid enzymes FeSOD and APX had larger relative increases than other, non-plastid specific SODs or peroxidases. In addition, non-enzymatic defence against hydroxyl radicals was doubled in UV treated leaves as compared to controls. In UV treated leaves, the extent of activation of ROS neutralizing capacities followed a peroxidases > hydroxyl-radical neutralization > SOD order. These results suggest that highly effective hydrogen peroxide neutralization is the focal point of surviving UV-inducible oxidative stress and argue against a direct signalling role of hydrogen peroxide in maintaining adaptation to UV, at least in laboratory experiments

Towards understanding vacuolar antioxidant mechanisms: a role for fructans?

Recent in vitro, in vivo and theoretical experiments strongly suggest that sugar-(like) molecules counteract oxidative stress by acting as genuine ROS scavengers. A concept was proposed to include the vacuole as a part of the cellular antioxidant network. According to this view sugars and sugar-like vacuolar compounds work in concert with vacuolar phenolic compounds and the “classic” cytosolic antioxidant mechanisms. Among the biologically relevant ROS (H2O2, O2•- and •OH), hydroxyl radicals are the most reactive and dangerous species since there are no enzymatic systems known to neutralize them in any living beings. Therefore, it is important to study in more detail the radical reactions between •OH and different biomolecules, including sugars. Here, we used Fenton reactions to compare the •OH scavenging capacities of a range of natural vacuolar compounds to establish relationships between antioxidant capacity and chemical structure and to unravel the mechanisms of •OH-carbohydrate reactions. The in vitro work on the •OH scavenging capacity of sugars and phenolic compounds revealed a correlation between structure and •OH scavenging capacity. The number and position of C=C type of linkages in phenolic compounds greatly influences antioxidant properties. Importantly, the splitting of disaccharides and oligosaccharides emerged as a predominant outcome of the •OH-carbohydrate interaction. Moreover, non-enzymatic synthesis of new fructan oligosaccharides was found starting from 1-kestotriose. Based on these and previous findings, a working model is proposed describing the putative radical reactions involving fructans and secondary metabolites at the inner side of the tonoplast and in the vacuolar lumen.status: publishe

Carbon nanotubes quench singlet oxygen generated by photosynthetic reaction centers

Photosensitizers may convert molecular oxygen into reactive oxygen species (ROS) including, e.g., singlet oxygen (O-1(2)), superoxide anion (O-2(-center dot)), and hydroxyl radicals ((OH)-O-center dot), chemicals with extremely high cyto- and potential genotoxicity. Photodynamic ROS reactions are determinative in medical photodynamic therapy (cancer treatment with externally added photosensitizers) and in reactions damaging the photosynthetic apparatus of plants (via internal pigments). The primary events of photosynthesis take place in the chlorophyll containing reaction center protein complex (RC), where the energy of light is converted into chemical potential. O-1(2) is formed by both bacterial bacteriochlorophylls and plant RC triplet chlorophylls in high light and if the quenching of O-1(2) is impaired. In plant physiology, reducing the formation of the ROS and thus lessening photooxidative membrane damage (including the RC protein) and increasing the efficiency of the photochemical energy conversion is of special interest. Carbon nanotubes, in artificial systems, are also known to react with singlet oxygen. To investigate the possibility of O-1(2) quenching by carbon nanotubes in a biological system, we studied the effect of carbon nanotubes on O-1(2) photogenerated by photosynthetic RCs purified from purple bacteria. 1,3-Diphenylisobenzofuran (DPBF), a dye responding to oxidation by O-1(2) with absorption decrease at 420nm was used to measure O-1(2) concentrations. O-1(2) was produced either from a photosensitizer (methylene blue) or from triplet photosynthetic RCs and the antioxidant capacity of carbon nanotubes was assessed. Less O-1(2) was detected by DPBF in the presence of carbon nanotubes, suggesting that these are potential quenchers of this ROS. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Effect of L-2286 administration on the activity of PKC isoenzymes.

<p>Representative Western blot analysis of PKC pan βII^Ser660 and PKC α/βII^Thr638/641 phosphorylation and densitometric evaluations are shown (n = 4). Values are means±S.E.M. WKY: normotensive age-matched control rats. SHR-C: 30 week-old spontaneously hypertensive rats, SHR-L: 30 week-old spontaneously hypertensive rats treated with L-2286 for 24 weeks. ^*p<0.01 vs. WKY, ^†p<0.01 vs. SHR-C.</p

L-2286 treatment moderately influenced the echocardiographic parameters in 30 weeks old SHRs.

<p>WKY: normotensive age-matched control rats, n = 7, SHR-C: SHR age-matched control rats, n = 8, SHR-L: n = 9, SHR treated with L-2286 for 24 weeks.EF^30w: ejection fraction, F^30w: fractional shortening, LVEDV^30w: left ventricular (LV) end-diastolic volume, LVESV^30w: LV end-systolic volume, Septum^30w: thickness of septum, PW^30w: thickness of posterior wall, RWT^30w: relative wall thickness, LV mass^30w: weights of LVs. Values are mean±S.E.M.</p>a<p>p<0.05 (vs. WKY group),</p>b<p>p<0.05 (vs. SHR-C group).</p