The increased susceptibility to hydrogen peroxide of the (post)-ischemic rat heart is associated with the magnitude of the low molecular weight iron pool

Recently we have shown that intracellular low molecular weight (LMW) iron increases during ischemia. It is hypothesized that this increase in LMW iron during ischemia underlies the reported hydrogen peroxide toxicity toward ischemic hearts. To investigate this hypothesis, rat hearts were subjected to 15 min of no-flow ischemia and reperfused with buffer saturated against 95% N2 and 5% CO2 (anoxic reperfusuion) for 7 min. Hearts were then swithched to buffer saturated against 95% O2 and 5% CO2 (reoxygenation) to assess functional recovery. The cardiac function recovered to 80 ± 7% of the preischemic value. When the anoxic reperfusion was applied in the presence of 10 μM hydrogen peroxide, functional recovery after reoxygenation was 47 ± 7%. Hearts that were perfused with deferoxamine before ischemia and then subjected to ischemia and anoxic reperfusion in the presence of 10 μM hydrogen peroxide recovered to 78 ± 8%. Immediate reoxygenation after ischemia led to only 45 ± 6% recovery of function. During ischemia, LMW iron increased from 49 ± 45 to 183 ± 45 pmol/mg protein (p < .05) and decreasedto 58 ± 38 pmol/mg protein (p < .05) during the subsequent anoxic perfusion. Rat hearts preloaded with deferoxamine showed a slightly higher LMW iron content than normal (85 ± 23 and 49 ± 45 pmol/mg protein, respectively; n.s.), which showed a small, nonsignificant increase up to 136 ± 42 pmol/mg protein after 15 min of ischemia. No significant changes were found in reduced and oxidized glutathione content and glutathione peroxidase or catalase activities under those conditions. Our results indicate that hydrogen peroxide toxicity is determined by the amount of catalytic iron in the LMW pool and not by a decrease in antioxidant defense capacity to hydrogen peroxide

Valorization of sweet corn (Zea mays) cob by extraction of valuable compounds

The main objective of this study was to investigate the proximate, mineral and phytochemical compositions of sweet corn cob (SCC), often neglected and regarded as agricultural waste. Compositional analysis showed that more than 60% of SCC was composed of insoluble dietary fibre, with cellulose being the major constituent. Results also showed that SCC can be a good source of non-essential protein and minerals (phosphorus,potassium and manganese). SCC had a total phenolic content of 6.74 g GAE kg-1 dry weight DW), of which bound phenolics were predominant. The bound phenolics fraction showed the highest antioxidant capacity in all three antioxidant capacity assays (TEAC, FRAP and DPPH) and contained the highest amount of ferulic and p-coumaric acid. The main carotenoids present in SCC were β-carotene, zeaxanthin and lutein. This investigation shows that SCC can be a potential source of natural colorant (carotenoids), antioxidants (phenolics)and nutritional supplements (proteins and phytochemicals)

Using bond-length dependent transferable force constants to predict vibrational entropies in Au-Cu, Au-Pd, and Cu-Pd alloys

A model is tested to rapidly evaluate the vibrational properties of alloys with site disorder. It is shown that length-dependent transferable force constants exist, and can be used to accurately predict the vibrational entropy of substitutionally ordered and disordered structures in Au-Cu, Au-Pd, and Cu-Pd. For each relevant force constant, a length- dependent function is determined and fitted to force constants obtained from first-principles pseudopotential calculations. We show that these transferable force constants can accurately predict vibrational entropies of L1$_{2}$-ordered and disordered phases in Cu$_{3}$Au, Au$_{3}$Pd, Pd$_{3}$Au, Cu$_{3}$Pd, and Pd$_{3}$Au. In addition, we calculate the vibrational entropy difference between L1$_{2}$-ordered and disordered phases of Au$_{3}$Cu and Cu$_{3}$Pt.Comment: 9 pages, 6 figures, 3 table

First-principles equation of state and phase stability for the Ni-Al system under high pressures

The equation of state (EOS) of alloys at high pressures is generalized with the cluster expansion method. It is shown that this provides a more accurate description. The low temperature EOSs of Ni-Al alloys on FCC and BCC lattices are obtained with density functional calculations, and the results are in good agreement with experiments. The merits of the generalized EOS model are confirmed by comparison with the mixing model. In addition, the FCC phase diagram of the Ni-Al system is calculated by cluster variation method (CVM) with both spin-polarized and non-spin-polarized effective cluster interactions (ECI). The influence of magnetic energy on the phase stability is analyzed. A long-standing discrepancy between ab initio formation enthalpies and experimental data is addressed by defining a better reference state. This aids both evaluation of an ab initio phase diagram and understanding the thermodynamic behaviors of alloys and compounds. For the first time the high-pressure behavior of order-disorder transition is investigated by ab initio calculations. It is found that order-disorder temperatures follow the Simon melting equation. This may be instructive for experimental and theoretical research on the effect of an order-disorder transition on shock Hugoniots.Comment: 27 pages, 12 figure