Overproduction of nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) may be an important factor in the pathogenesis of amyotrophic lateral sclerosis (ALS). Owing to their ability to permeate through biological membranes, excess NO and H(2)O(2) may be present in the media surrounding motor neurones. Anti-oxidative defence enzymes (ADEs) in erythrocytes are capable of detoxifying reactive oxygen species (produced endogenously or exogenously), but may also be structurally modified and inactivated by reactive oxygen and nitrogen species. Both balanced and coordinated ADE activities are of utmost importance for their correct physiological function. We determined activity of the following ADEs: copper-zinc superoxide dismutase (CuZn SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) in erythrocytes from sporadic ALS patients [SALS (-/+)], familial ALS patients with the Leu144Phe mutation in the SOD1 gene [FALS (+/+)], asymptomatic carriers with the Leu144Phe mutation in the SOD1 gene (+/-), and control subjects (-/-). We also examined the in vitro effect of diethyldithiocarbamate (DDC) on CuZn SOD activity in erythrocytes from FALS patients, SALS patients and control subjects. The influence of the Leu144Phe mutation and/or disease was apparent for ADE activities measured in all three patient groups. The SOD1 gene mutation decreased CuZn SOD and GSH-Px activity (two-way ANOVA, significant mutation effect). We noted that the disease also contributed to decreased CuZn SOD activity in SALS patients in comparison with the control group (two-way ANOVA, mutation and disease effect). The disease also influenced CAT and GR activity. CAT activity was decreased in both SALS and FALS patients. In all three patient groups, GR activity was higher than in the control group. Finally, DDC inhibited CuZn SOD activity in erythrocytes from control subjects, FALS (Leu144Phe) patients and SALS patients; however, its effect was more pronounced and significant in FALS patients. Changes in erythrocyte ADE activities suggest that oxidative stress, involved in the motor neurone pathogenesis of SALS and FALS, also has systemic effects. Differences in ADE systems between the study groups revealed the presence of different types of oxidative pressure, indicating the potential additional benefit of individually designed anti-oxidant cocktail therapies.

Background and purpose:  The effects of hydrogen peroxide (H₂O₂) on uterine smooth muscle are not well studied. We have investigated the effect and the mechanism of action of exogenous hydrogen peroxide on rat uteri contractile activity [spontaneous and calcium ion (Ca²⁺)‐induced] and the effect of such treatment on anti‐oxidative enzyme activities.Experimental approach:  Uteri were isolated from virgin Wistar rats and suspended in an organ bath. Uteri were allowed to contract spontaneously or in the presence of Ca²⁺ (6 mM) and treated with H₂O₂ (2 µM–3 mM) over 2 h. Anti‐oxidative enzyme activities (manganese superoxide dismutase‐MnSOD, copper‐zinc superoxide dismutase‐CuZnSOD, catalase‐CAT, glutathione peroxidase‐GSHPx and glutathione reductase‐GR) in H₂O₂‐treated uteri were compared with those in uteri immediately frozen after isolation or undergoing spontaneous or Ca²⁺‐induced contractions, without treatment with H₂O₂. The effect of inhibitors (propranolol, methylene blue, L‐NAME, tetraethylamonium, glibenclamide and 4‐aminopyridine) on H₂O₂‐mediated relaxation was explored.Key results:  H₂O₂ caused concentration‐dependent relaxation of both spontaneous and Ca²⁺‐induced uterine contractions. After H₂O₂ treatment, GSHPx and MnSOD activities were increased, while CuZnSOD and GR (In Ca²⁺‐induced rat uteri) were decreased. N^ω‐nitro‐L‐arginine methyl ester antagonized the effect of H₂O₂ on Ca²⁺‐induced contractions. H₂O₂‐induced relaxation was not affected by propranolol, potentiated by methylene blue and antagonized by tetraethylamonium, 4‐aminopyridine and glibenclamide, with the last compound being the least effective.Conclusions and implications:  H₂O₂ induced dose‐dependent relaxation of isolated rat uteri mainly via changes in voltage‐dependent potassium channels. Decreasing generation of reactive oxygen species by stimulation of anti‐oxidative pathways may lead to new approaches to the management of dysfunctional uteri.

Recent findings indicate that nitric oxide (NO*) over-production might be an important factor in the pathogenesis of sporadic amyotrophic lateral sclerosis (SALS). We measured significantly higher concentrations of uric acid and thiol group-containing molecules (R-SH groups) in the cerebrospinal fluid (CSF) from SALS patients compared to controls. The above factors, together with a slightly increased free iron concentration found in the CSF, favour conditions necessary for the formation of the dinitrosyl iron complex, capable of NO* bio-transformation. Thus, we performed ex vivo saturation of CSF (from both SALS patients and controls) with NO*. A decrease in the level of R-SH was found. This was more pronounced in the CSF from SALS patients. In the CSF from SALS patients the production of nitrite and hydroxylamine was greater than that observed in the CSF from controls. Moreover, we also found increased Cu,Zn-SOD activity in the CSF from SALS patients (when compared to control subjects) but no activity corresponding to Mn-SOD in any CSF samples. As Cu,Zn-SOD can react with nitroxyl forming NO*, the conditions for a closed, but continuous, loop of NO* biotransformation are present in the CSF of ALS patients.