Evidence for Oxidative Stress in the Subthalamic Nucleus in Progressive Supranuclear Palsy

Increased free radical production and oxidative stress have been proposed as pathogenic mechanisms in several neurodegenerative disorders. Free radicals interact with biological macromolecules, such as lipids, which can lead to lipid peroxidation. A well-established marker of oxidative damage to lipids is malondialdehyde (MDA). We measured tissue MDA levels in the subthalamic nucleus (STN) and cerebellum from 11 progressive supranuclear palsy (PSP) cases and 11 age-matched control cases using sensitive HPLC techniques. In PSP, a significant increase in tissue MDA levels was observed in the STN when compared with the age-matched control group. By contrast, no significant difference between tissue MDA content was observed in cerebellar tissue from the same PSP and age-matched control cases. These results indicate that lipid peroxidation may play a role in the pathogenesis of PSP.     

Effect of DL-alpha-lipoic acid on mitochondrial enzymes in aged rats.

Mitochondrial dysfunction appears to contribute to some of the loss of function accompanying ageing. Mitochondria from aged tissue use oxygen inefficiently impairing ATP synthesis and results in increased oxidant production. A high flux of oxidants not only damages mitochondria, but other important cell biomolecules as well. In the present investigation, the levels of lipid peroxidation, oxidized glutathione, non-enzymatic antioxidants and the activities of mitochondrial enzymes were measured in liver and kidney mitochondria of young and aged rats before and after lipoic acid supplementation. In both liver and kidney increase in the levels of mitochondrial lipid peroxidation and oxidized glutathione and decrease in the levels of antioxidants and the activities of mitochondrial enzymes were observed in aged rats. DL-alpha-lipoic acid supplemented aged rats showed a decrease in the levels of lipid peroxidation and oxidized glutathione and increase in the levels of reduced glutathione, vitamins C and E and the activities of mitochondrial enzymes like isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, NADH-dehydrogenase and cytochrome-c-oxidase. Thus, lipoic acid reverses the age-associated decline in endogenous low molecular weight antioxidants and mitochondrial enzymes and, therefore, may lower the increased risk of oxidative damage that occurs during ageing. From our results it can be concluded that lipoic acid supplementation enhances the activities of mitochondrial enzymes and antioxidant status and thereby protects mitochondria from ageing.     

Basal Lipid Peroxidation in Substantia Nigra Is Increased in Parkinson''s Disease

Polyunsaturated fatty acid (PUFA) levels (an index of the amount of substrate available for lipid peroxidation) were measured in several brain regions from patients who died with Parkinson's disease and age-matched control human postmortem brains. PUFA levels were reduced in parkinsonian substantia nigra compared to other brain regions and to control tissue. However, basal malondialdehyde (MDA; an intermediate in the lipid peroxidation process) levels were increased in parkinsonian nigra compared with other parkinsonian brain regions and control tissue. Expressing basal MDA levels in terms of PUFA content, the difference between parkinsonian and control substantia nigra was even more pronounced. Stimulating MDA production by incubating tissue with FeSO4 plus ascorbic acid, FeSO4 plus H2O2, or air alone produced lower MDA levels in the parkinsonian substantia nigra, probably reflecting the lower PUFA content. These results may indicate that an increased level of lipid peroxidation continues to occur in the parkinsonian nigra up to the time of death, perhaps because of continued exposure to excess free radicals derived from some endogenous or exogenous neurotoxic species.     

Glutathione Cycle Impairment Mediates Aβ-induced Cell Toxicity

Membrane lipid peroxidation processes yield products that may react with proteins to cause oxidative modification. Recently, we demonstrated that the control of cytosolic and mitochondrial redox balance and oxidative damage is one of the primary functions of NADP⁺-dependent isocitrate dehydrogenase (ICDH) through to supply NADPH for antioxidant systems. When exposed to lipid peroxidation products, such as malondialdehyde (MDA), 4-hydroxynonenal (HNE) and lipid hydroperoxide, ICDH was susceptible to oxidative damage, which was indicated by the loss of activity and the formation of carbonyl groups. The structural alterations of modified enzymes were indicated by the change in thermal stability, intrinsic tryptophan fluorescence and binding of the hydrophobic probe 8-anilino 1-napthalene sulfonic acid. Upon exposure to 2,2′-azobis(2-amidinopropane) hydrochloride (AAPH), which induces lipid peroxidation in membrane, a significant decrease in both cytosolic and mitochondrial ICDH activities were observed in U937 cells. Using immunoprecipitation and immunoblotting, we were able to isolate and positively identify HNE adduct in mitochondrial ICDH from AAPH-treated U937 cells. The lipid peroxidation-mediated damage to ICDH may result in the perturbation of the cellular antioxidant defense mechanisms and subsequently lead to a pro-oxidant condition.     

Beneficial effects of DL-alpha-lipoic acid on cyclophosphamide-induced oxidative stress in mitochondrial fractions of rat testis

The present study investigated the protective efficacy of dl-alpha-lipoic acid on the peroxidative damage and abnormal antioxidant levels in the mitochondrial fraction of testis in cyclophosphamide (CP) administered rats. Male Wistar rats of 140+/-20 g were categorized into four groups. Two groups were administered CP (15 mg/kg body weight once a week for 10 weeks by oral gavage) to induce testicular toxicity; one of these groups received lipoic acid treatment (35 mg/kg body weight intraperitoneally once a week for 10 weeks, 24 h prior to CP administration). A vehicle-treated control group and a lipoic acid drug control group were also included. The mitochondrial fraction of untreated CP-exposed testis showed 1.84-fold increase in lipid peroxidation, along with a significant (P<0.001) increase in hydrogen peroxide levels. In CP-exposed rats, we observed abnormal changes in the activities/levels of mitochondrial enzymic (superoxide dismutase, glutathione peroxidase and glutathione reductase) and non-enzymic (reduced glutathione, ascorbate and alpha-tocopherol) antioxidants. CP-treated rats also showed decline in the activities of mitochondrial enzymes such as succinate dehydrogenase, malate dehydrogenase and isocitrate dehydrogenase. In contrast, rats pretreated with lipoic acid showed normal lipid peroxidation and antioxidant defenses, thereby showing the protection rendered by lipoic acid.     

Aconitase and ATP synthase are targets of malondialdehyde modification and undergo an age-related decrease in activity in mouse heart mitochondria

The main purpose of this study was to identify mitochondrial proteins that exhibit post-translational oxidative modifications during the aging process and to determine the resulting functional alterations. Proteins forming adducts with malondialdehyde (MDA), a product of lipid peroxidation, were identified by immunodetection in mitochondria isolated from heart and hind leg skeletal muscle of 6-, 16-, and 24-month-old mice. Aconitase, very long chain acyl coenzyme A dehydrogenase, ATP synthase, and alpha-ketoglutarate dehydrogenase were detected as putative targets of oxidative modification by MDA. Aconitase and ATP synthase from heart exhibited significant decreases in activity with age. Very long chain acyl coenzyme A dehydrogenase and alpha-ketoglutarate dehydrogenase activities were unaffected during aging in both heart and skeletal muscle. This suggests that the presence of a post-translational oxidative modification in a protein does not a priori reflect an alteration in activity. The biological consequences of an age-related decrease in aconitase and ATP synthase activities may contribute to the decline in mitochondrial bioenergetics evident during aging.     

Ascorbic acid and alpha-tocopherol as potent modulators on arsenic induced toxicity in mitochondria

Arsenic exists ubiquitously in our environment and various forms of arsenic circulate in air, water, soil and living organisms. Since arsenic compounds have shown to exert their toxicity chiefly by generating reactive oxygen species, we have evaluated the effect of antioxidants ascorbic acid and alpha-tocopherol on lipid peroxidation, antioxidants and mitochondrial enzymes in liver and kidney of arsenic exposed rats. A significant increase in the level of lipid peroxidation and decrease in the levels of antioxidants and in the activities of mitochondrial enzymes were observed in arsenic intoxicated rats. Co-administration of arsenic treated rats with ascorbic acid and alpha-tocopherol showed significant reduction in the level of lipid peroxidation and elevation in the levels of ascorbic acid, alpha-tocopherol, glutathione and total sulfhydryls and in the activities of isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, NADH-dehydrogenase and cytochrome c oxidase. From our results, we conclude that ascorbic acid and alpha-tocopherol alleviate arsenic- induced alterations in mitochondria.     

Protective effect of ursodeoxycholic acid on liver mitochondrial function in rats with alloxan-induced diabetes: link with oxidative stress

We investigated the effects of ursodeoxycholic acid (UDCA) on mitochondrial functions and oxidative stress and evaluated their relationships in the livers of rats with alloxan-induced diabetes. Diabetes was induced in male Wistar rats by a single alloxan injection (150 mg kg^− 1 b.w., i.p.). UDCA (40 mg kg^− 1 b.w., i.g., 30 days) was administered from the 5th day after the alloxan treatment. Mitochondrial functions were evaluated by oxygen consumption with Clark oxygen electrode using succinate, pyruvate + malate or palmitoyl carnitine as substrates and by determination of succinate dehydrogenase and NADH dehydrogenase activities. Liver mitochondria were used to measure chemiluminiscence enhanced by luminol and lucigenin, reduced liver glutathione and the end-products of lipid peroxidation. The activities of both NADH dehydrogenase and succinate dehydrogenase as well as the respiratory control (RC) value with all the substrates and the ADP/O ratio with pyruvate + malate and succinate as substrates were significantly decreased in diabetic rats. UDCA developed the beneficial effect on the mitochondrial respiration and oxidative phosphorylation parameters in alloxan-treated rats, whereas the activities of mitochondrial enzymes were increased insignificantly after the administration of UDCA. The contents of polar carbonyls and MDA as well as the chemiluminescence with luminol were elevated in liver mitochondria of diabetic rats. The treatment with UDCA normalized all the above parameters measured except the MDA content. UDCA administration prevents mitochondrial dysfunction in rats treated with alloxan and this process is closely connected with inhibition of oxidative stress by this compound.     

Alteration of DMBA-induced oxidative stress by additive action of a modified indigenous preparation--Kalpaamruthaa

The present study investigated the protective efficacy of the novel preparation named as Kalpaamruthaa (KA, includes Semecarpus anacardium Linn nut milk extract (SA), dried powder of Phyllanthus emblica fruit and honey) on the peroxidative damage and abnormal antioxidant levels in the hepatic mitochondrial fraction of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma rats. Female Sprague-Dawley rats of weight 180+/-10 g were categorized into six groups. Three groups were administered DMBA (25 mg/rat dissolved in olive oil, orally) to induce mammary carcinoma. One of these groups received KA treatment (300 mg/kg b.wt., orally) and other group received SA (200 mg/kg b.wt., orally) for 14 days after 90 days of DMBA induction. Vehicle-treated control and drug control groups were also included. The hepatic mitochondrial fraction of untreated DMBA rats showed 2.96-fold increase in MDA content when compared to control rats and abnormal changes in the activities/levels of mitochondrial enzymic (superoxide dismutase, glutathione peroxidase and glutathione reductase) and non-enzymic (glutathione, vitamin C and vitamin E) antioxidants were observed. DMBA-treated rats also showed decline in the activities of mitochondrial enzymes such as succinate dehydrogenase, alpha-ketoglutarate dehydrogenase, malate dehydrogenase and isocitrate dehydrogenase. In contrast, rats treated with SA and KA showed normal lipid peroxidation antioxidant defenses and mitochondrial enzymes, thereby showing the protection rendered by SA and KA. Although, KA treatment exhibited more profound effect in inhibiting DMBA-induced oxidative stress than sole SA treatment. Results of the study indicate that the anticarcinogenic activity of KA during DMBA-initiated mammary carcinogenesis is mediated through alteration of hepatic antioxidant status as well as modulation of TCA cycle enzymes. On the basis of the observed results, KA can be considered as a readily accessible, promising and novel cancer chemopreventive agent.     

Inactivation of NADP+-dependent isocitrate dehydrogenase by lipid peroxidation products

Membrane lipid peroxidation processes yield products that may react with proteins to cause oxidative modification. Recently, we demonstrated that the control of cytosolic and mitochondrial redox balance and oxidative damage is one of the primary functions of NADP₊-dependent isocitrate dehydrogenase (ICDH) through to supply NADPH for antioxidant systems. When exposed to lipid peroxidation products, such as malondialdehyde (MDA), 4-hydroxynonenal (HNE) and lipid hydroperoxide, ICDH was susceptible to oxidative damage, which was indicated by the loss of activity and the formation of carbonyl groups. The structural alterations of modified enzymes were indicated by the change in thermal stability, intrinsic tryptophan fluorescence and binding of the hydrophobic probe 8-anilino 1-napthalene sulfonic acid. Upon exposure to 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH), which induces lipid peroxidation in membrane, a significant decrease in both cytosolic and mitochondrial ICDH activities were observed in U937 cells. Using immunoprecipitation and immunoblotting, we were able to isolate and positively identify HNE adduct in mitochondrial ICDH from AAPH-treated U937 cells. The lipid peroxidation-mediated damage to ICDH may result in the perturbation of the cellular antioxidant defense mechanisms and subsequently lead to a pro-oxidant condition.     

Preservation of boar semen at 18 degrees C induces lipid peroxidation and apoptosis like changes in spermatozoa

Boar sperm functions, lipid peroxidation status, mitochondrial membrane potential (DeltaPsi(m)) and membrane permeability (apoptosis like features) were assessed during liquid preservation. Four ejaculates each from four Hampshire boars were extended with Beltsville Thawing Solution and preserved at 18 degrees C. At 0, 24, 48, 72 and 96 h of storage, each ejaculate was examined for sperm functions, lipid peroxidation, DeltaPsi(m), and membrane permeability. The lipid peroxidation status of the sperm was assessed based on the malonaldehyde (MDA) levels. Detection of DeltaPsi(m) was done using 3,3'-dihexyloxacarbocyanine iodide [DiOC(6)(3)]/propidium iodide (PI) assay and Yo-pro-1/PI assay was used to detect change in plasma membrane permeability. The sperm motility, viability and acrosomal integrity declined significantly (p<0.05) from 0 to 96 h of preservation. At the start of the preservation, the MDA levels (nM/10(9) sperm) were low in sperm (99.83+/-2.69) and seminal plasma (191.98+/-11.58), which gradually increased up to the 96 h of storage. Highest negative correlation (r value) was observed between MDA levels and sperm motility (-0.97), live percent (-0.97), acrosomal integrity (-0.97) and hypo-osmotic sperm swelling test (HOSST) positive sperm percentage (-0.98). Strong positive correlation was observed between HOSST positive sperm percentage and intact acrosome percentage (r=0.98). There was a significant (p<0.05) increase in the sperm cells with low DeltaPsi(m) from 0 to 96 h of preservation. Before preservation, 14.85+/-4.66% of sperm cells of the ejaculate showed low mitochondrial membrane potential, whereas after 96 h of preservation, this proposition of cells increased up to 32.00+/-6.25%. The apoptotic sperm population was 8.33+/-2.31% in fresh semen, while this population was 25.19+/-4.25% at 96 h of preservation and the difference was significant (p<0.05). The findings of the present study revealed that liquid preservation of boar semen at 18 degrees C induces lipid peroxidation, decrease mitochondrial membrane potential and increase the plasma membrane permeability.     

Protective effect of Phyllanthus fraternus against carbon tetrachloride-induced mitochondrial dysfunction.

The effect of carbon tetrachloride administration on liver mitochondrial function and the protective effect of an aqueous extract of Phyllanthus fraternus were studied in rats. The following changes were observed in mitochondria due to the administration of carbon tetrachloride. 1) A decrease in the rate of respiration, respiratory control ratio and P/O ratio using glutamate and malate or succinate as substrates. 2) A decrease in the activities of NADH dehydrogenase (35%), succinate dehydrogenase (76%) and cytochrome c oxidase (51%). The rate of electron transfer through site I, site II and site III was studied independently and found to be significantly decreased. 3) A decrease in the content of cytochrome aa3 (34%). 4) A significant decrease in the levels of phospholipids particularly cardiolipin and a significant increase in the lipid peroxide level was observed. The carbon tetrachloride induced toxicity may be partly due to the lipid peroxidation and partly due to the effect on protein synthesis. Administration of rats with an aqueous extract of P. fraternus prior to carbon tetrachloride administration showed significant protection on the carbon tetrachloride induced mitochondrial dysfunction on all the parameters studied.     

Effect of succinate on mitochondrial lipid peroxidation. 2. The protective effect of succinate against functional and structural changes induced by lipid peroxidation

The damaging effects of ADP/Fe/NADPH-induced lipid peroxidation were studied on the enzymes and membranes of rat liver mitochondria. Succinate, an inhibitor of mitochondrial lipid peroxidation, prevented or delayed most of the damage caused by the peroxidation on different mitochondrial structures and functions. There were marked abnormalities on the electrophoretic pattern of mitochondrial proteins during the course of lipid peroxidation. The disappearance of particular polypeptide bands and the accumulation of high-molecular-weight aggregates could be observed. Succinate was found to delay these effects. As a consequence of lipid peroxidation the succinate oxidase activity of mitochondria was decreased. The succinate dehydrogenase enzyme and the component(s) of the respiratory chain were inactivated. Succinate prevented the inactivation of succinate dehydrogenase but did not protect the other components of terminal oxidation chain. From the matrix enzymes the glutamate dehydrogenase retained its full activity but the NADP-linked isocitrate dehydrogenase was inactivated. The mitochondrial membranes became permeable to large protein molecules. Succinate prevented the inactivation of isocitrate dehydrogenase and delayed the release of protein molecules from mitochondria.     

Lipid peroxidation in hepatocyte cell cultures: Modulation by free radical scavengers and iron

Summary Rat hepatocytes were isolated and then maintained in serum-free cell culture medium for 24 h. The amount of malondialdehyde (MDA) accumulated in the medium was assayed and used as a measure of lipid peroxidation. The acivity of lactate dehydrogenase (LDH) and urea were measured in the medium and used as indicators of hepatocellular viability and function. The effects of iron; desferrioxamine mesylate (Desferal), an iron chelator; and mannitol, a hydroxyl free radical scavenger were investigated. The addition of iron, Fe² resulted in a three-fold increase in the levels of MDA. Desferal inhibited the production of MDA and blocked the effect of Fe²⁺. Neither iron nor Desferal had any effect on LDH or urea levels. Mannitol had no effect on MDA or urea production, but caused a 4 to 8-fold increase in the LDH levels in the medium. The results show that iron is involved in the mechanism of lipid peroxidation in hepatocyte cultures but suggest that as a pathologic event lipid peroxidation is not expressed in terms of viability during the first 24 h of hepatocyte culture.     

Neuronal Mitochondrial Toxicity of Malondialdehyde: Inhibitory Effects on Respiratory Function and Enzyme Activities in Rat Brain Mitochondria

Malondialdehyde (MDA) is a product of oxidative damage to lipids, amino acids and DNA, and accumulates with aging and diseases. MDA can possibly react with amines so as to modify proteins and inactivate enzymes; it can also modify nucleosides so as to cause mutagenicity. Brain mitochondrial dysfunction is a major contributor to aging and neurodegenerative diseases. We hypothesize that MDA accumulated during aging targets mitochondrial enzymes so as to cause further mitochondrial dysfunction and additional contributions to aging and neurodegeneration. Herein, we investigated the neuronal mitochondrial toxic effects of MDA on mitochondrial respiration and activities of enzymes (mitochondrial complexes I–V, α-ketoglutarate dehydrogenase (KGDH) and pyruvate dehydrogenase (PDH)), in isolated rat brain mitochondria. MDA depressed mitochondrial membrane potential, and also showed a dose-dependent inhibition of mitochondrial complex I- and complex II-linked respiration. Complex I and II, and PDH activities were depressed by MDA at ≥0.2 μmol/mg; KGDH and complex V were inhibited by ≥0.4 and ≥1.6 μmol MDA/mg, respectively. However, MDA did not have any toxic effects on complex III and IV activities over the range 0–2 μmol/mg. MDA significantly elevated mitochondrial reactive oxygen species (ROS) and protein carbonyls at 0.2 and 0.002 μmol/mg, respectively. As for the antioxidant defense system, a high dose of MDA slightly decreased mitochondrial GSH and superoxide dismutase. These results demonstrate that MDA causes neuronal mitochondrial dysfunction by directly promoting generation of ROS and modifying mitochondrial proteins. The results suggest that MDA-induced neuronal mitochondrial toxicity may be an important contributing factor to brain aging and neurodegenerative diseases. Special issue article in honor of Dr. Akitane Mori.     

The role of prednisolone and epinephrine on gastric tissue and erythrocyte antioxidant status in adrenalectomized rats.

It has been believed that overproduction of free radicals and/or deficiency of antioxidant systems, and stress hormones may play a role in etiopathogenesis of many diseases, including gastric ulcer. This study evaluated whether there was an effect of adrenalectomy on lipid peroxidation [malondialdehyde (MDA)] and antioxidant [superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione (GSH) levels] systems in gastric tissue and erythrocyte in rats. As well, the impacts of administration of prednisolone and epinephrine on these systems in adrenalectomized rats were investigated. Thirty-three rats were randomly grouped as sham-operated (group I), adrenalectomized (group II), adrenalectomized + prednisolone (group III) and adrenalectomized + epinephrine (group IV). After experimental procedures, blood and gastric tissues samples were taken from each animal in all groups. Colorimetric assays were employed to determine gastric tissue and erythrocyte levels of MDA and GSH, and SOD and GPX activities. Adrenalectomy in group II rats caused a marked decrease of SOD and GPX activities and MDA levels, and an increase of GSH levels in gastric tissue and erythrocyte, when compared to sham-operated rats. However, especially epinephrine injection after adrenalectomy resulted in a significantly increase of measured antioxidant enzyme activities and GSH levels in both gastric tissue and erythrocyte. These results indicate that adrenalectomy appeared to alter the levels of antioxidants and lipid peroxidation product in gastric tissue and erythrocyte. Thus, the present study provides a physiological regulatory role of adrenal gland in the maintenance of oxidant/antioxidant balance in gastric tissue and erythrocyte.     

The association between oxidative stress and obstructive lung impairment in patients with COPD

An oxidant/antioxidant imbalance is thought to play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). We hypothesized that antioxidant capacity reflected by erythrocyte glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) activities, and serum levels of the lipid peroxidation product malondialdehyde (MDA), may be related to the severity of obstructive lung impairment in patients with COPD. Erythrocyte GPx, SOD and CAT activities, and serum levels of MDA were measured in 79 consecutive patients with stable COPD. Pulmonary functional tests were assessed by body plethysmography. Moderate COPD (FEV1 50-80%) was present in 23, and severe COPD (FEV1 < 50%) in 56 patients. Erythrocyte GPx activity was significantly lower, and serum MDA levels were significantly higher in patients with severe COPD compared to patients with moderate COPD (GPx: 43.1+/-1.5 vs. 47.7+/-2.9 U/gHb, p<0.05, MDA: 2.4+/-0.1 vs. 2.1+/-0.1 nmol/ml, p<0.05). Linear regression analysis revealed a significant direct relationship between FEV1 and erythrocyte GPx activity (r = 0.234, p<0.05), and a significant inverse relationship between FEV1 and serum MDA levels (r = -0.239, p<0.05). However, no differences were observed in the erythrocyte SOD and CAT activities between the two groups of patients with different severity of COPD. Findings of the present study suggest that antioxidant capacity reflected by erythrocyte GPx activity and serum levels of the lipid peroxidation product MDA are linked to the severity of COPD.     

Oxidant-antioxidant imbalance in the erythrocytes of sporadic amyotrophic lateral sclerosis patients correlates with the progression of disease

Free radicals are implicated in numerous disease processes including motor neuron degeneration (MND). Antioxidant defense enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G-6-PDH) in the erythrocytes are capable of detoxifying reactive oxygen species produced endogenously or exogenously. In the present study, the extent of lipid peroxidation (LPO) and antioxidant defenses were evaluated in the erythrocytes of 20 sporadic amyotrophic lateral sclerosis (ALS) patients and 20 controls. We observed that lipid peroxidation in the erythrocytes of amyotrophic lateral sclerosis patients significantly increased with respect to controls (P<0.001). On the other hand, catalase activity was found to be significantly lower (P<0.001). The activities of glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione levels were also found to be significantly reduced in ALS patients compared to healthy subjects (P<0.001, P<0.01 and P<0.01, respectively). It was further observed that lipid peroxidation started to increase and catalase, glutathione reductase, glucose-6-phosphate dehydrogenase enzyme activities and glutathione levels started to decrease as amyotrophic lateral sclerosis progressed from 6 to 24 months, suggesting a correlation between these parameters and duration of amyotrophic lateral sclerosis. This study confirms the involvement of oxidative stress during the progression of amyotrophic lateral sclerosis and the need to develop specific peripheral biomarkers.     

Selenium and malondialdehyde content and glutathione peroxidase activity in maternal and umbilical cord blood and amniotic fluid

Placenta tissue may be a major source of lipid peroxidation products in pregnancy. It was proven that placental peroxidation activity increases with gestation. Selenium (Se), as an essential constituent of glutathione peroxidase (GSH-Px), takes part in the reduction of hydrogen peroxides and lipid peroxides. Malondialdehyde (MDA) is a major breakdown product split off from lipid peroxides. In this study, Se and MDA content and GSH-Px activity were measured in blood and plasma taken from 20 apparently healthy nonpregnant women between 19 and 38 yr of age and from 115 unselected pregnant women between 17 and 45 yr of age (35 in the first trimester, 22 in the second trimester, 38 in the third trimester, and 20 within 2 d of delivery). Samples of umbilical cord blood and amniotic fluid were taken from women in the second and third trimesters and at delivery. The Se content was measured by atomic absorption spectrometry (AAS), plasma MDA concentration by thiobarbituric acid reaction, and Se-dependent GSH-Px spectrometrically. Blood and plasma Se contents of nonpregnant women were below those considered adequate, indicating low selenium intake. In comparison to nonpregnant women, pregnant women had significantly decreased whole-blood and plasma Se levels in the second and third trimesters and at delivery. The significant drop of whole-blood SeGSH-Px activity was observed in the first trimester of pregnancy and its lower activity was maintained until delivery. A significant drop in plasma SeGSH-Px activity occurred in the second trimester and attained the minimal level at delivery. The Se level and SeGSH-Px activity in maternal and umbilical cord blood were at similar levels. Amniotic-fluid SeGSH-Px activity was nondetectable or exceptionally low and its Se content remained unchanged during pregnancy. Plasma levels of MDA were significantly decreased in the second and third trimesters and at delivery. The fetal blood plasma at birth had a lower MDA level compared to the levels of MDA of their mothers at delivery. A low, but significant inverse correlation existed between blood SeGSH-Px activity and plasma MDA content and between plasma Se and plasma MDA contents during pregnancy. A significant decrease of Se and SeGSH-Px activities (antioxidant enzyme) in both blood and plasma suggests a possible drop in total antioxidant status during pregnancy. Elevated MDA plasma levels might be the result of increased lipid peroxidation in placental tissue during pregnancy.     

Effects of pyrroline and pyrrolidine nitroxides on lipid peroxidation in heart tissue of rats treated with doxorubicin

Protection from doxorubicin-induced lipid peroxidation in vivo by two pyrroline and pyrrolidine nitroxides, Pirolin, PL, and Pirolid, PD, was examined in the heart tissue of rats treated with this drug. The level of lipid peroxidation was estimated on the basis of MDA content. A considerable (three-fold) increase in the MDA amount was found in heart homogenates from rats injected with doxorubicin, whereas no significant changes in MDA content compared to control were observed in cardiomyocytes treated with the nitroxides (Pirolin or Pirolid) only. Pirolin injected simultaneously with doxorubicin showed antioxidative effect and markedly attenuated lipid peroxidation in the heart tissue caused by this drug. In contrast to Pirolin, structurally related Pirolid was ineffective in the protection of heart myocytes from DOX-induced lipid peroxidation.