Ceslava Kairane

Two antioxidative lactobacilli strains as promising probiotics.

Two antioxidative strains tentatively identified as Lactobacillus fermentum, E-3 and E-18, were isolated from intestinal microflora of a healthy child. Survival time of these strains in the presence of reactive oxygen species (ROS), like hydrogen peroxide, superoxide anions and hydroxyl radicals, was significantly increased compared with a non-antioxidative strain, and also was quite similar to a highly ROS resistant strain of Salmonella typhimurium. E-3 and E-8 contain a remarkable level of glutathione, express Mn-SOD, which is important for the prevention of lipid peroxidation, and secrete hydrogen peroxide. Their significant antimicrobial activity combined with antioxidative properties may serve as defensive principles in the intestinal microbial ecosystem and overcome exo- and endogenous oxidative stress.

Acute immune response in respect to exercise-induced oxidative stress

The relationship between exhaustive exercise, oxidative stress, the protective capacity of the antioxidant defense system and cellular immune response has been determined. Exhaustive exercise in well-trained young men (n=19)-induced leukocytosis, decreased proportion of activated-lymphocyte subsets (CD4+ and CD8+) expressing CD69, decreased lymphocyte mitogenic response to concanavalin A (ConA) and phytohemagglutinin (PHA), increased lipid peroxidation, increased total antioxidant status (TAS) and catalase activity, immediately after exercise. Suppressed blood concentration of T-lymphocyte subsets (CD3+, CD4+, CD8+, NK), increased TAS and blood total glutathione (TGSH) in early recovery period (30 min after exercise) were found. Strong positive correlation was observed between TGSH and lymphocyte mitogenic response to ConA and PHA (r=0.85 and 0.85, respectively) immediately after exercise. Moderate positive correlation was observed between TAS and lymphocyte mitogenic response to PHA (r=0.59) immediately after exercise as well as between TAS and lymphocyte mitogenic response to PHA and ConA (r=0.69 and 0.54, respectively). Moderate to weak correlation was observed between TAS and conjugated dienes with exercise (r=0.66) as well as in 30-min recovery (r=0.50). After a short-term bout of exhaustive exercise, immune system was characterized by acute phase response, which was accompanied with oxidative stress. Suppression of the cellular immunity 30 min after exercise shows that this period is not enough for recovery after exhaustive exercise. The results suggest the interactions between exercise-induced oxidative stress and immune response.

Pretreating rats with hyperoxia attenuates ischemia-reperfusion injury of the heart.

Oxidative stress may precondition the heart. The present study investigated whether hyperoxia elicits a preconditioning-like response. Rats were kept in a hyperoxic (>95% O2) environment for 60 or 180 minutes. Hearts were Langendorff-perfused immediately or 24 hours after hyperoxia, and exposed to 25 minutes of global ischemia and 60 minutes of reperfusion. Whole blood was sampled after 60 and 180 minutes of hyperoxia for oxidative stress markers. Hearts were sampled immediately or 24 hours after hyperoxia for measurement of antioxidants, lipid peroxidation products, heat shock protein 72 and endothelial nitric oxide synthase. At the end of reperfusion after 1 h hyperoxia, infarct size was determined by tetrazolium staining. Hyperoxia increased serum levels of conjugated dienes, reduced serum antioxidative protection, reduced reperfusion arrhythmias in most groups, and improved myocardial function. Infarct size was reduced from 45% of myocardial tissue in controls to 22% in treated animals. The myocardial activity of antioxidant enzymes, content of heat shock protein 72, and endothelial nitric oxide synthase in myocardial tissue were not influenced. In conclusion, hyperoxia induces a low-graded systemic oxidative stress, improves postischemic cardiac function and reduces infarct size. The mediators of protection remain to be determined.

Pretreatment with methylprednisolone protects the isolated rat heart against ischaemic and oxidative damage

Methylprednisolone (MP), a synthetic glucocorticoid, is widely used clinically and experimentally as acute antiinflammatory treatment. The molecular actions of MP indicate that pretreatment with this drug may be cardioprotective. We investigated if giving rats MP prior to excising their hearts for Langendorff-perfusion protected cardiac function against oxidative stress, and if this was mediated by increasing antioxidant defence or influencing myocardial nitric oxide synthase (NOS). Rats (n=6–11 in each group) were injected with MP (40 mg/kg i.m.) or vehicle 24 and 12 h before Langendorff-perfusion with 30 min global ischaemia and 60 min reperfusion, or 10 min perfusion with 180 μmol/L hydrogen peroxide. Other hearts were exposed to 30 min global ischaemia 5 days after MP-injection. Additional hearts were sampled before, during, and after ischaemia for analyzing tissue activity of antioxidant enzymes. Tissue endothelial and inducible NOS (eNOS and iNOS) were investigated by immunoblotting and semiquantitative RT-PCR in a time-course after MP injection. Pretreatment with MP improved left ventricular function and increased coronary flow during postischaemic reperfusion, and this effect was sustained 5 days afterwards. When exposing hearts to hydrogen peroxide, MP improved coronary flow. Catalase, glutathione peroxidase, and oxidized glutathione were increased during reperfusion of MP-treated hearts compared to vehicle only. MP did not influence eNOS at protein or mRNA level. iNOS could not be detected by immunoblotting, indicating low cardiac enzyme content. Its mRNA initially increased the first hour after injection, thereafter decreased. In conclusions, pretreating rats with MP protects the heart against ischaemia-reperfusion dysfunction. This effect could be due to increase of tissue antioxidant activity during reperfusion. MP did not influence cardiac eNOS. mRNA for iNOS was influenced by MP, but the corresponding protein could not be detected.

Effect of antihypertensive treatment with candesartan or amlodipine on glutathione and its redox status, homocysteine and vitamin concentrations in patients with essential hypertension.

Objective To compare the effect of candesartan or amlodipine on concentrations of cellular markers of oxidative stress, plasma homocysteine and vitamins in hypertensive patients. Methods Forty-nine middle-aged patients with untreated stage I–II essential hypertension were recruited in a randomized double-blind double-dummy study to receive a daily dose either of 8 mg candesartan (n = 25) or 5 mg amlodipine (n = 24) for 16 weeks. Blood pressure, reduced glutathione (GSH) and oxidized glutathione (GSSG), glutathione redox ratio (GSSG : GSH) in red blood cells, plasma homocysteine, vitamin B12 and folic acid status were measured at baseline, at week 2 and at week 16. The same parameters were measured in 32 healthy age- and sex-matched controls. An increase in homocysteine of at least 2 μmol/l was considered significant. Results Hypertensive patients had significantly greater oxidative stress and homocysteine concentrations than controls. In addition to a significant decrease in blood pressure, in both treatment groups GSSG decreased (P < 0.03), GSSG : GSH had a tendency to decrease (P = 0.054), but homocysteine did not change. An increase in homocysteine concentration of at least 2 μmol/l was found in 12 patients (five in the candesartan group, seven in the amlodipine group), with a significant decrease in folic acid concentration and no changes in cellular oxidative stress. In patients with no increase in homocysteine concentration, both GSSG (P < 0.02) and GSSG : GSH (P = 0.051) decreased. GSH and vitamin B12 did not change in any of the groups studied. Conclusion: Untreated hypertension is associated with disturbed glutathione redox status and increased plasma homocysteine concentrations. Both candesartan and amlodipine had favourable effects on cellular oxidative stress, but the oxidative stress status did not decrease in patients with adverse changes in homocysteine.

The Effects of Different Antioxidants on the Activity of Cerebrocortical MnSOD and Na,K-ATPase from post mortem Alzheimer’s Disease and Age-matched Normal Brains

Among the markers and targets of the early phase of Alzheimers disease (AD) pathogenesis MnSOD (mitochondrial dysfunction) and Na-pump (disturbances in function/regulation) are often highlighted. This paper focused on comparison of the effects of three antioxidants on the activity of cerebrocortical MnSOD and Na,K-ATPase from post mortem Alzheimers disease and age-matched normal brains. Antioxidant compounds with different origins: natural glutathione, synthetic UPF peptides (glutathione analogues) and phytoestrogen genistein were investigated. Firstly, MnSOD and Na,K-ATPase activities were found to be decreased in the post mortem AD brains compared with age-matched controls. Secondly, GSH had no effect on MnSOD activity, but decreased Na,K-ATPase activity both in the control and AD brains. Thirdly, UPF1 and UPF17 increased MnSOD activity, and UPF17 suppressed Na,K-ATPase activity. Further studies are needed to clarify, if the inhibitory effect of UPF17 on Na,K-ATPase could abolish the beneficial effect gained from MnSOD activation. Both the antioxidative potential of genistein and its potency to up-regulate Na,K-ATPase activity make it an attractive candidate substance to suppress the early phase of the pathogenesis of AD.

Pre-treatment with hyperoxia before coronary artery bypass grafting : effects on myocardial injury and inflammatory response

Background:  In experimental studies, exposure to hyperoxia for a limited time before ischaemia induces a low‐grade systemic oxidative stress and evokes an (ischaemic) preconditioning‐like effect of the myocardium. We hypothesised that hyperoxia before cardioplegia could protect the myocardium against necrosis and stunning caused by ischaemia–reperfusion.

Characterization of UPF peptides, members of the glutathione analogues library, on the basis of their effects on oxidative stress-related enzymes.

Previously the authors have designed and synthesized a library of antioxidative glutathione analogues called UPF peptides which are superior to glutathione in hydroxyl radical elimination. This paper is a follow-up study which investigated the effects of the most promising members of the library (UPF1 and UPF17) on oxidative stress-related enzymes. At concentrations used in vivo experiments neither UPF peptide influenced the activity of glutathione peroxidase (GPx) when purified enzyme or erythrocyte lysate was used. At higher concentrations they inhibited GPx activity. UPF peptides had no effect on glutathione reductase (GR) activity. Also they, as well as glutathione itself, slightly increased MnSOD activity in human brain mitochondria and inhibited oxidative burst caused by neutrophil NAD(P)H oxidase. RT-PCR measurements showed that UPF1 and UPF17 have no effect on GPx and MnSOD expression level in human blood mononuclear cells. The results of this study confirm that investigated UPF peptides do not interfere with the enzymatic mechanisms of antioxidative defence and can be used as themselves or as a lead for the protector molecule design against excessive oxidative stress.

Wfs1-deficient animals have brain-region-specific changes of Na+, K+-ATPase activity and mRNA expression of α1 and β1 subunits

Mutations in the WFS1 gene, which encodes the endoplasmic reticulum (ER) glycoprotein, cause Wolfram syndrome, a disease characterized by juvenile‐onset diabetes mellitus, optic atrophy, deafness, and different psychiatric abnormalities. Loss of neuronal cells and pancreatic β‐cells in Wolfram syndrome patients is probably related to the dysfunction of ER stress regulation, which leads to cell apoptosis. The present study shows that Wfs1‐deficient mice have brain‐region‐specific changes in Na+,K+‐ATPase activity and in the expression of the α1 and β1 subunits. We found a significant (1.6‐fold) increase of Na‐pump activity and β1 subunit mRNA expression in mice lacking the Wfs1 gene in the temporal lobe compared with their wild‐type littermates. By contrast, exposure of mice to the elevated plus maze (EPM) model of anxiety decreased Na‐pump activity 1.3‐fold in the midbrain and dorsal striatum and 2.0‐fold in the ventral striatum of homozygous animals compared with the nonexposed group. Na‐pump α1‐subunit mRNA was significantly decreased in the dorsal striatum and midbrain of Wfs1‐deficient homozygous animals compared with wild‐type littermates. In the temporal lobe, an increase in the activity of the Na‐pump is probably related to increased anxiety established in Wfs1‐deficient mice, whereas the blunted dopamine function in the forebrain of Wfs1‐deficient mice may be associated with a decrease of Na‐pump activity in the dorsal and ventral striatum and in the midbrain after exposure to the EPM.

Diverse Effects of Glutathione and UPF Peptides on Antioxidant Defense System in Human Erythroleukemia Cells K562

The main goal of the present paper was to examine the influence of the replacement of γ-Glu moiety to α-Glu in glutathione and in its antioxidative tetrapeptidic analogue UPF1 (Tyr(Me)-γ-Glu-Cys-Gly), resulting in α-GSH and UPF17 (Tyr(Me)-Glu-Cys-Gly), on the antioxidative defense system in K562 cells. UPF1 and GSH increased while UPF17 and α-GSH decreased the activity of CuZnSOD in K562 cells, at peptide concentration of 10 μM by 42% and 38% or 35% and 24%, respectively. After three-hour incubation, UPF1 increased and UPF17 decreased the intracellular level of total GSH. Additionally, it was shown that UPF1 is not degraded by γ-glutamyltranspeptidase, which performs glutathione breakdown. These results indicate that effective antioxidative character of peptides does not depend only on the reactivity of the thiol group, but also of the other functional groups, and on the spatial structure of peptides.