The study analysed the effect of modification of phenolic resin with alkylresorcinols and H2O2 on properties of softwood and hardwood plywood resinated with such modified PF resins. Conducted tests showed that the application of PF resin modified with alkylresorcinols makes it possible to manufacture plywood with improved properties, especially bond quality, than those of the control plywood pressed under identical conditions. In turn, the introduction of H2O2 both to pure PF resin and resin modified with alkylresorcinols improves properties of plywood as a result of enhanced reactivity and increased chemical adhesion of resin to wood. Moreover, applied PF resin modification methods make it possible to manufacture plywood with very good properties at pressing time reduced by 25%.
The objective of this study was to investigate the effects of inoculum concentration, plant post-inoculation incubation temperature and exogenous hydrogen peroxide (H2O2) on the induction of the hypersensitive response (HR) in Nicotiana tabacum against Xanthomonas perforans. Inoculation of leaves with X. perforans at a concentration of 108 CFU · ml–1 and incubation of plants at 30°C resulted in the strongest HR elicitation. Furthermore, an exogenous supply of H2O2 accelerated X. perforans-induced HR, whereas in planta H2O2 removal by application of catalase led to a delay in HR development. Our data suggest that H2O2 has an important role in HR of N. tabacum against X. perforans.
The purpose of this study was establishing the basic energetic parameters of amoeba Acanthamoeba castellaniimitochondria respiring with malate and their response to oxidative stress caused by hydrogen peroxide in the presence of Fe2+ions. It appeared that, contrary to a previous report (Trocha LK, Stobienia O (2007) Acta Biochim Polon 54: 797), H2O2-treated mitochondria of A. Castellanii did not display any substantial impairment. No marked changes in cytochrome pathway activity were found, as in the presence of an inhibitor of alternative oxidase no effects were observed on the rates of uncoupled and phosphorylating respiration and on coupling parameters. Only in the absence of the alternative oxidase inhibitor, non-phosphorylating respiration progressively decreased with increasing concentration of H2O2, while the coupling parameters (respiratory control ratio and ADP/O ratio) slightly improved, which may indicate some inactivation of the alternative oxidase. Moreover, our results show no change in membrane potential, Ca2+uptake and accumulation ability, mitochondrial outer membrane integrity and cytochrome crelease for 0.5–25 mM H2O2-treated versuscontrol (H2O2-untreated) mitochondria. These results indicate that short (5 min) incubation of A. Castellanii mitochondria with H2O2 in the presence of Fe2+ does not damage their basic energetics.
Mitochondrial respiration is considered to provide reactive oxygen species (ROS) as byproduct of regular electron transfer. Objections were raised since results obtained with isolated mitochondria are commonly transferred to activities of mitochondria in the living cell. High electrogenic membrane potential was reported to trigger formation of mitochondrial ROS involving complex I and III. Suggested bioenergetic parameters, starting ROS formation, widely change with the isolation mode. ROS detection systems generally applied may be misleading due to possible interactions with membrane constituents or electron carriers. Avoiding these problems no conditions reported to transform mitochondrial respiration to a radical source were confirmed. However, changing the physical membrane state affected the highly susceptible interaction of the ubiquinol/&C1 redox complex such that ROS formation became possible.
The aim of this paper was to examine the effects of chorfenvinphos on serum concentrations of transition metals, hydrogen peroxide and malondialdehyde (a lipid peroxidation index), and on the activity of superoxide dismutase in erythrocytes. Male Wistar rats were treated with vehicle or 0.02, 0.1 and 0.5 x LD50 of chlorfenvinphos and samples were collected at 1, 24 and 48 hr after treatment. The experiments were approved by the Local Ethics Committee. We demonstrated a decreased concentration of copper serum, which is accompanied by the increased activity of superoxide dismutase. The changes observed in the concentrations of copper can be explained by its displacement from serum to erythrocytes. We also observed increased levels of zinc serum (after intoxication with CVP at doses of 0.02 and 0.1 x LD50) and iron, as well as enhancement in hydrogen peroxide serum and malondialdehyde concentration. The changes in serum Zn concentration probably resulting from cellular membrane damage and the increase in serum iron concentration, is probably caused by its release from haemoglobin. The changes of serum Fe levels seems to have no effect on lipid peroxidation. We concluded that in acute intoxication with chlorfenvinphos — organophosphorus insecticide, the non-cholinesterase mechanismes are involved.